Browsing by Author "Liu, Yu"
Now showing 1 - 20 of 26
- Results Per Page
- Sort Options
Item A Longitudinal Study of the Stress-buffering Effect of Social Support on Postpartum Depression(2019-05) Yu, Miao; Rubin, Allen; Sampson, McClain M.; Liu, YuBackground: Postpartum depression (PPD) impacts about one out of eight new mothers, and it has a unique and pervasive impact on a woman, a child, and a family. Research has demonstrated that perceived social support has a positive effect on PPD. Nevertheless, there has been disagreement on how social support influences depression. The overall goal of this study is to test the stress-buffering effect of social support on postpartum depression by using two different definitions of stress and following a rigorous procedure of research design and statistical analyses. Methods: Secondary longitudinal data were used to answer the research question. In total, 512 first-time mothers comprised the study sample. Parenting stress and difficult life circumstances measured at six months postpartum was used to predict the changes in depressive symptoms from 6 to 12 months postpartum and social support measured at six months postpartum was used as a moderator between stress and PPD. Structural Equation Modeling (SEM) was adopted for statistical analyses. Results: The results showed that parental distress, one component of parenting stress, had a significant long-lasting impact on PPD. The other two components of parenting stress, difficult child and parent-child dysfunctional interaction, did not have a direct effect on PPD. Difficult life circumstance also showed a significant enduring influence on PPD. Social support was not found to moderate the influence of parenting stress or difficult life circumstances on PPD. A significant direct effect of social support on depression was not found by this study either. Neither the stress-buffering theory of social support nor the main-effect model of social support was endorsed by the longitudinal study. Conclusions: The findings encourage social workers to be mindful of the impact of parental distress and difficult life circumstances on new mothers’ mental health. Problem-solving tools and interventions that aimed to enhance self-mastery and self-efficacy are recommended to help new mothers be more resilient in dealing with parental distress and daily hassles. Measures for social support and parenting stress with higher capability of discrimination should be used in future stress-buffering research. More longitudinal studies with shorter lags between measurement occasions are warranted in order to figure out at what point social support is most useful for new mothers’ mental health.Item A Longitudinal Study of the Stress-buffering Effect of Social Support on Postpartum Depression(2019-05) Yu, Miao; Rubin, Allen; Sampson, McClain M.; Liu, YuAbstract Background: Postpartum depression (PPD) impacts about one out of eight new mothers, and it has a unique and pervasive impact on a woman, a child, and a family. Research has demonstrated that perceived social support has a positive effect on PPD. Nevertheless, there has been disagreement on how social support influences depression. The overall goal of this study is to test the stress-buffering effect of social support on postpartum depression by using two different definitions of stress and following a rigorous procedure of research design and statistical analyses. Methods: Secondary longitudinal data were used to answer the research question. In total, 512 first-time mothers comprised the study sample. Parenting stress and difficult life circumstances measured at six months postpartum was used to predict the changes in depressive symptoms from 6 to 12 months postpartum and social support measured at six months postpartum was used as a moderator between stress and PPD. Structural Equation Modeling (SEM) was adopted for statistical analyses. Results: The results showed that parental distress, one component of parenting stress, had a significant long-lasting impact on PPD. The other two components of parenting stress, difficult child and parent-child dysfunctional interaction, did not have a direct effect on PPD. Difficult life circumstance also showed a significant enduring influence on PPD. Social support was not found to moderate the influence of parenting stress or difficult life circumstances on PPD. A significant direct effect of social support on depression was not found by this study either. Neither the stress-buffering theory of social support nor the main-effect model of social support was endorsed by the longitudinal study. Conclusions: The findings encourage social workers to be mindful of the impact of parental distress and difficult life circumstances on new mothers’ mental health. Problem-solving tools and interventions that aimed to enhance self-mastery and self-efficacy are recommended to help new mothers be more resilient in dealing with parental distress and daily hassles. Measures for social support and parenting stress with higher capability of discrimination should be used in future stress-buffering research. More longitudinal studies with shorter lags between measurement occasions are warranted in order to figure out at what point social support is most useful for new mothers’ mental health.Item Aberrant Expression of Embryonic Mesendoderm Factor MESP1 Promotes Tumorigenesis(2019-08) Tandon, Neha 1986-; Liu, Yu; Frigo, Daniel E.; Dauwalder, Brigitte; Lin, Chin-Yo; Lin, Weei-ChinLung cancer is the leading cause of cancer-related deaths in the United States, with KRAS and EGFR known as driver oncogenes for the disease. Adding to these are “lineage-survival oncogenes” where tumor survival depends on the aberrant expression of master transcriptional regulators of cell-lineages. Here, by integrating various patient gene expression datasets, we identified that basic helix- loop-helix transcription factor MESP1, a master regulator of mesendoderm development, has a previously-unknown association with Non-Small Cell Lung Cancer (NSCLC). We found that MESP1 expression correlates with poor prognosis in NSCLC patients, and is critical for proliferation and survival of NSCLC-derived cell lines, thus, implicating MESP1 as a lung cancer oncogene. Ectopic MESP1 expression cooperates with the loss of tumor suppressor ARF to transform murine fibroblasts. Xenografts of MESP1-knockdown cells showed decreased tumor growth in vivo. Global transcriptome analysis revealed a MESP1 DNA-binding dependent gene signature associated with various hallmarks of cancer, suggesting that the transcription activity of MESP1 is most likely responsible for its oncogenic abilities. These observations demonstrate MESP1 as a previously-unknown lineage survival oncogene in NSCLC.Item Assessing the Function and Control of miR-322(424)/503 on Skeletal Muscle(2018-10-18) DesJarlais, Alex; Syed, AnamMuscle atrophy, a common complication of many diseases such as cancer, COPD, and heart failure, has no effective treatment approaches to date. Recently, we identified miR-322/503 as a significant regulator of muscle homeostasis and may play an important role in muscular degenerative diseases. Our objective is to explore the phenotypes and mechanisms of skeletal muscle-specific overexpression and the knock-out of miR-322/503. We found that miR-322/503 regulated skeletal muscle homeostasis through inhibition of elF4E and elF4G1, which are two critical components in translation initiation process.Item Associations of Rape Myth Belief and Perceived School Support with The Likelihood of Reporting Sexual Assault(2018-12) Neisler, Julie; Wiesner, Margit F.; Liu, Yu; McKinney, Lyle; Ford-McCartney, DevanBackground: Sexual assault occurs at high rates (one in five students) at institutions of higher education in the U.S. and is known to have a negative impact on students’ affective, physical, financial, and academic outcomes. Only a small percentage of these sexual assault crimes are reported to institutions, preventing students from gaining access to support services that act as protective factors against negative outcomes. Little is known about what predicts a student’s likelihood of reporting prior to having experienced an assault (hereafter referred to as “likelihood of reporting”), and whether external factors, such as perception of school support, influence this likelihood. Purpose: The aims of the proposed study were to examine (1) whether survey items related to likelihood of reporting and perceived school support map to underlying latent multiple-indicator constructs that are invariant across male and female students; (2) whether a student’s rape myth belief, which has a strong theoretical alignment to survivors’ endorsed reasons for not reporting their sexual assault, is related to the likelihood of reporting; and (3) whether perceived school support moderates the relationship between rape myth belief and likelihood of reporting among university students. Methods: Participants (N = 4596) included undergraduate, graduate, and professional students from a large, tier 1, public institution in southwest United States. A cross-sectional survey assessed participants’ demographic characteristics, rape myth belief, likelihood of reporting, and perceived school support. Confirmatory Factor Analysis was used to examine the factor structure of latent variables. Structural regression models were estimated to determine the effect of rape myth belief on likelihood of reporting, and the moderating effect of perceived campus climate on this relationship. Results: Confirmatory factor analysis and Chi-Square difference tests supported weak threshold invariance for both likelihood of reporting and perceived school support latent variables. Rape myth belief significantly predicted likelihood of reporting for both males and females when controlling for classification (year in school), residence (living on vs. off campus), and race/ethnicity such that higher levels of rape myth belief were associated with lower levels of likelihood of reporting, p < 0.001 (Cohen’s f2 females = 0.139, males = 0.147). Perceived school support significantly moderated the relationship between rape myth belief and likelihood of reporting when controlling for classification, residence, and race/ethnicity on all levels of the moderator, such that any level of perceived school support, the relationship between rape myth belief and likelihood of reporting was negative, p < 0.001 (Cohen’s f2 females = 0.012, males = 0.024). Conclusion: An individual’s belief in false rape myths and their perception of the support that an institution would provide in the instance of reporting a sexual assault significantly influence the student’s likelihood of reporting. Institutions of higher education should seek to implement interventions that challenge false beliefs and educate students on the support and resources that the institution provides. This growing body of research must aim to positively impact proactive education and support efforts in order to ensure the safety and opportunity for success for all students.Item Bioengineering A Three-Dimensional Cardiac Left Ventricle(2015-05) Patel, Nikita M.; Birla, Ravi K.; May, Elebeoba E.; Liu, Yu; McConnell, Bradley K.; Omurtag, AhmetHypoplastic left heart syndrome (HLHS) is a congenital condition characterized by an underdeveloped left ventricle (LV). The current treatment options are surgery and/or heart transplant. Current tissue engineering strategies focus on graft models. The development of an engineered 3D cardiac LV would provide a therapeutic option to overcome current treatment limitations. A series of five models, to understand the ideal LV platform, fabricate and optimize a bioengineered open ventricle chamber and complete the chamber with a trileaflet valve, were produced in this research. Models were designed to emulate the human neonate LV geometry; molds were used to produce chitosan scaffolds. Functional models were fabricated by culturing rat neonatal primary cardiac cells on the chitosan scaffold. Chitosan was shown to be biocompatible with suitable material properties. An open chamber model was designed and optimized with respect to cellularization efficiency and function, using a novel seeding strategy and bioreactor, respectively; cellularized constructs demonstrated cardiac myocyte biopotential activity with contractions and pressure generation. Trileaflet valves were engineered and fitted into the open chamber to complete the bioengineered ventricle. The outcome of this research is the production of a complete bioengineered 3D cardiac LV.Item Cardiomyopathy Progression Due to Overexpression of miRNA- 322/503(2020-09-29) Rajput, Jahnvi; Shrestha, ShreestiDilated cardiomyopathy is the leading cause of death among heart disease patients. It is characterized by a decrease in blood flow through the heart due to enlargement and weakness of the left ventricle. The miRNA, mir-322/503, was found to be increased in expression in dilated cardiomyopathy. Our lab has found that overexpression of miRNA- 322/503 in the heart using a doxycycline induced mouse model, leads to heart failure that exhibits characteristics of dilated cardiomyopathy. The main objective of this research was to monitor this heart failure progression over time. In vivo mice models were given a doxycycline diet for a month and body weight was monitored. Heart specific tissues were collected at days 0, 7, 14, 21 and 28 and stained with H&E stain. Heart stress markers were analyzed using qPCR. We found overexpression of miRNA- 322/503 leads to body weight loss, loss of cardiac function through dilation of ventricular chambers and wall thinning, increase in stress markers ANP (Atrial natriuretic peptide) and BNP (Brain natriuretic peptide), and a decrease in α-MHC (Myosin heavy chain).Item Chemical Approaches to Investigate HIV-1 Rev-RRE RNA Interactions(2017-08) Karri, Nanda 1983-; Fox, Robert O.; Bark, Steven J.; Liu, Yu; Willson, Richard C.Two separate crystal structures of the Rev dimer have been solved. One structure features details of the A:A dimerization interface and the other features details of the B:B interface. While the binding of multiple copies of Rev is required for its RNA transport function, the details of the interactions by which Rev interacts with RRE RNA remain elusive. To investigate this, the RWZ2 fragment, which was later named sIIB was fused to a tRNA scaffold and Rev:sIIB-tRNA complexes were analyzed by various biophysical experiments. Establishing the binding strength and stoichiometry in solution has been frustrated by the need for specific chemical labeling of the Rev protein. We have successfully installed a fluorescent probe at the C-terminal end of Rev and demonstrated the binding of RevL with chimeric tRNAPhe-sIIB RNA molecule. We sought to address whether Rev shows any preference in binding (A:A vs. B:B) and dimerization of RNA. We took the approach of making covalently crosslinked Rev dimers in a manner that is consistent with the geometry and conformation of the crystallized Rev dimers. This thesis details the solid phase semisynthetic approach, experimental procedures, and results of the studies done on Rev and the RRE.Item Computationally modeling the effectiveness of Pd/Cu as a diesel oxidation catalyst(2023-04-13) Hammond, Nikki; Hoang, NhiDiesel engine emissions are a major cause of air pollution producing carbon monoxide (CO), hydrocarbons, nitrogen oxide molecules (NOx), and particulate matter (PM). Low temperature combustion engines offer a promising solution for reducing NOx and PM emissions, but in turn, the lower temperature interferes with the diesel oxidation catalyst (DOC) causing an increase in CO and hydrocarbon emissions. To combat this, the development of new catalysts is critical. Recent studies show that a Pd/Cu alloy could lead to inhibition-free low temperature oxidation reactions, but the mechanistic origin of the improvement over Pd/Pt alloys remains unknown. To elucidate the mechanism, we first used SurfaceEP, a machine-learning package to rapidly estimate binding energies and identified certain ensembles with promising oxygen binding properties. For isolated Pd atoms in the surface of Cu, we obtained density functional theory (DFT) data for all CO oxidation steps. We are currently incorporating this information into a kinetic Monte Carlo (kMC) model, which will allow us to study the mechanism and activity of well-defined site ensembles. This will provide the necessary fundamental insight that is required to further improve the composition and surface architecture of Pd/Cu diesel oxidation catalyst.Item Discovering Pathogenic Variants Associated with Tricuspid Atresia through Whole Exome Sequencing(2019-12) Hoggard, Jason Andrew 1986-; Gunaratne, Preethi H.; Schwartz, Robert J.; D'Alessandro, Lisa; Morris, Shaine A.; Liu, Yu; McConnell, Bradley K.Congenital heart disease (CHD) is the most common birth defect, present in 1/110 live births, and those considered critical (CCHD) require surgical intervention within the first year of life. A rare form of CCHD, tricuspid atresia, is present in 1/10,000 live births in the United States and accounts for approximately 1-3% of all CHD. It is characterized by the absence of the tricuspid, or right atrioventricular, valve and presents with additional phenotypes that are required to survive to birth. At this point, very few genetic studies have been conducted on this condition and the results have been very sparse. Currently 22q11 deletion (DiGeorge syndrome), 8p23 (GATA4 region), 4q31 (NFB), and 3p (TGFBR2) have been found associated with the few tricuspid atresia patients that have been characterized through limited genetic testing. In this study, a retrospective chart review was undertaken on the largest cohort of tricuspid atresia patients (n=234) and includes the first genetic testing outcome results for any tricuspid atresia retrospective review study. Following this, a family with various cardiac phenotypes including tricuspid atresia and bicuspid aortic valve was assessed via whole exome sequencing (WES) to discover pathogenic variants. Following the compilation of all genetic testing data from the literature, the retrospective review, and the family WES, a common pathway was identified that is disrupted in all subjects without a syndromic diagnosis. The pathway, beginning with TGF-beta and RANKL signaling, involves the expression of NFATC1 via NFkappaB activity and NFATC1 transcription factor function regulation by a complex including TAB2. WES in 342 patients with congenital cardiac left-sided lesions revealed extensive genetic heterogeneity. This is the only other study to screen a large cohort of patients with WES and reported 28 candidate variants in 27 genes. Of these, 17 genes were not previously associated with CHD. Our study is the first to begin identifying a potential genetic etiology for tricuspid atresia which is a right-sided lesion.Item Environmental Pollutants Disrupting Nuclear Receptor Signaling and Metabolism in Zebrafish(2015-08) Kalasekar, Sharanya 1987-; Gustafsson, Jan-Åke; Bondesson, Maria; Schwartz, Robert J.; Eichberg, Joseph; Liu, Yu; Kakadiaris, Ioannis A.Obesity affects a large proportion of the world’s population, and the alarming rates of increase in its incidence have necessitated several research efforts investigating the risk factors for the disease. Apart from genetic and lifestyle factors, environmental exposure to chemicals, such as the estrogen diethylstilbestrol and the anti-diabetic Thiazolidinediones, are known to induce weight gain in animals and humans. Estrogens and Thiazolidinediones act via the Estrogen Receptors (ERs) and the Peroxisome Proliferator-Activated receptor gamma (PPARγ), respectively. In this study, we identify environmental endocrine disrupting chemicals (EDCs), which may act through ERs or PPARγ, to affect metabolism in zebrafish. Furthermore, we investigate the mechanism by which widely prevalent flame retardants and PPARγ agonists tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) induce aberrant lipid accumulation in zebrafish. Through our studies, we have identified 32 environmental chemicals from EPA’s ToxCast library of 309 chemicals as being estrogenic in zebrafish. Through extensive surveys of previously published in vitro and in vivo studies of these chemicals, we infer that in vitro tests for estrogenicity may not fully predict toxicity in vivo, and posit that zebrafish be used in whole-organism high-throughput screens to supplement in vitro chemical prioritization efforts for toxicological testing. We have also established a zebrafish-based quantitative phenotypic screening platform to investigate the effect of environmental chemicals on yolk utilization. Zebrafish utilize the lipid-rich yolk during development, and, we posit that chemical disruption of yolk-lipid utilization could suggest abnormal lipid mobilization and energy demand in developing zebrafish. Using this platform we evaluated nine chemicals, and found that while pesticide prochloraz delays yolk utilization, another pesticide butralin, the mammalian obesogen tributyltin, and TBBPA and TCBPA increase yolk lipid consumption by zebrafish larvae. Transcriptomic analysis of TBBPA, TCBPA and TBT in zebrafish showed that, just as in mammals, these chemicals induce pathways driving adipogenesis. These chemicals also induced the expression of several genes related to lipid metabolism and inflammation. Although further studies are needed to determine the sequence of molecular events triggered by these chemicals, we posit that TBBPA, TCBPA and TBT may act through these pathways to induce obesity in zebrafish, and possibly, in humans.Item Fusion Proteins as Selective Inducers of Constitutive Activity and Tools to Discriminate the Biased Signaling Profile of β2 Adrenoceptor Ligands(2021-12) Lucero Garcia Rojas, Emilio Yaroslav; McConnell, Bradley K.; Bond, Richard A.; Ruan, Ke-He; Dixon, Richard A. F.; Knoll, Brian J.; Liu, YuThe β2AR is the prototypical G protein coupled receptor (GPCR) known to orchestrate different cellular responses by the stimulation of specific signaling pathways. The best-established signaling pathways for the β2AR are the canonical Gs pathway and the alternative β arrestin 2 (βarr2) pathway. Exploring each pathway separately remains a challenging task due to the dynamic nature of the receptor. Here, we fused the β2AR with its cognate transducers, Gαs and βarr2, using short linkers as a novel approach for restricting the conformation of the receptor and preferentially activating one of its two signaling pathways. We characterized the behavior of our fusion proteins β2AR-Gαs and β2AR-βarr2 in HEK293 cells by measuring their constitutive activity, transducer recruitment, and pharmacologic modulation. Our fusion proteins show (a) steric hindrance from the reciprocal endogenous transducers, (b) constitutive activity of the β2AR for the signaling pathway activated by the tethered transducer, and (c) pharmacologic modulation by β2AR ligands. Since both fusion proteins remained functional to ligand stimuli, we quantified the pharmacological properties of affinity, efficacy, and potency for cAMP accumulation and ERK1/2 phosphorylation as surrogates of the Gs and βarr2 pathways, respectively, in selected β2AR ligands. Using these pharmacological parameters, we developed a mathematical method for direct ligand bias quantification based on the well-known transduction coefficient ratios formula (ΔΔ log(τ/KA)). Our method has the advantage of quantifying an ‘absolute’ value of signaling bias for any ligand that shows negative or positive efficacy at any signaling pathway. The term absolute is used here to highlight that a reference ligand is not required in our method as each ligand becomes its own reference. Regarding the isolated constitutive activity observed for each fusion protein, we used this feature to induce a gain-of-function mechanism in the human lung non-tumorigenic epithelial cell line, BEAS-2B cells. This immortalized human bronchial epithelial cell line has immunomodulatory properties through cytokine release mediated by β2AR stimulation. Our findings suggest that each signaling pathway of the β2AR is biased towards either the Th1 or Th2 inflammatory response regulating the immune phenotype of respiratory diseases. Our data implies our fusion proteins can be used as tools to isolate the function elicited by a unique signaling pathway in physiologically relevant cell types.Item General Education Teacher Use of Evidence-Based Practices for Students with Autism Spectrum Disorder(2022-05-12) Izuno-Garcia, Amy; Keller-Margulis, Milena A.; Mire, Sarah S.; Liu, Yu; Hassett, Kristen S.Background: The prevalence of autism spectrum disorder (ASD) has increased in recent years (Maenner et al., 2020), which also means more students with ASD are receiving services in schools. Students on the autism spectrum are at an increased risk for emotional, behavioral, social, and academic deficits, which can impact their performance in the classroom (e.g., Ashburner et al., 2010). As more students with ASD are integrated into the general education classroom, it is important to examine general education teacher cognitive factors and self-report of behaviors, as they are increasingly responsible for instructing these students. Specifically, investigating what evidence-based practices (EBPs) they report using and what factors may influence the choice of these practices (e.g., attitudes, self-efficacy, priorities, etc.) can help identify ways to better support general education teachers who are instructing students with ASD. One framework that may help researchers in this area is implementation science, which is the study of factors that influence the full and effective use of EBPs (Fixsen et al., 2005). To enhance acceptability and uptake and use of EBPs in the education sector, this framework underscores the importance of understanding factors such as knowledge, attitudes, and social validity of the EBP, as well as other relevant factors such as self-efficacy and instructional priorities. Understanding the systems that influence children with ASD, such as schools and specifically teacher practices, can ultimately reveal ways to improve outcomes for this population. Purpose: The aims of this study were to examine which EBPs general education teachers report using for students with ASD and what factors influence their reports of EBP use in general education classrooms. Methods: The study involved an anonymous, online survey, which included screening questions to determine eligibility for the study, a demographic characteristics survey, the Evidence-Based Practice Attitude Scale (EBPAS; Aarons, 2004), Teacher Self-Efficacy for Students with Autism Scale (TSEAS; Love, 2016), and questions about instructional priorities (Knight et al., 2019), as well as knowledge, social validity, and self-reported use of EBPs (Sulek et al., 2019). Results: The total sample size was 123 general education teachers. General education teachers reported using EBPs at least once per week, but not every day for their students with ASD. The most frequently used EBPs, reported as being used sometimes (in order from most to least), were antecedent-based interventions, music-mediated interventions, and prompting. The EBPs reported as being least frequently used (between less than once per week and more than once a week but not everyday) and included functional behavior analysis, extinction, and discrete trial training. Hierarchical linear regression analyses revealed that EBP knowledge and EBP social validity were significantly associated with self-reported EBP use. However, years of teaching experience, access to professional development resources, attitudes towards EBPs, and self-efficacy in working with students with ASD did not significantly predict teachers reports of using EBPs in the classroom. Conclusion: The EBPs that general education teachers self-reported as using most frequently for students with ASD were ones they had more knowledge about and found more acceptable and feasible for implementing in their classrooms. To increase use of EBPs by general education teachers for students with ASD, teacher preparation programs, professional development sessions, and continuing education workshops should aim to increase the knowledge of and social validity surrounding EBPs.Item Large Scale Docking of Chemical Compound Against CDK20(2017-10-12) Nazarian, Amir; Wang, Xin; Yu, Fang; Liu, YuRegulation of the eukaryotic cell cycle is directed by the activation of cyclin-dependent kinases (CDKs). CDK’s are known to interact with cyclins and are inhibited by enzymes like p27. Literature has identified CDK20 as an interesting target for cancer treatment because a CDK20 knockout causes cell growth reduction and eventually termination. By using CDK2, CDK5, and CDK7 structures a computational homology model for CDK20 was previously generated. I hypothesize that if the computational model of CDK20 is docked against a library of chemical lead-like compounds; then some of those compounds might inhibit the CDK20 complexing with a Cyclin or an Enzyme Inhibitor (like KIP1). I computationally docked molecules from a ZINC database using Autodock-Vina to score CDK20/inhibitor complexes. I mapped protein amino acid side chain interactions with the small molecule in the docked complex and ranked drug leads for analysis. This research has significant impact if one of these drug leads can be matured into a drug candidate and used in a cancer therapy. It also has near term impact by providing small molecule disrupters of CDK20 that can be used in basic research in our function studies of lung cancer using H1437, H2122, and A549 cell lines.Item Minority Stress as Traumatic Stress: The Relationship between Discrimination, Social Support, Posttraumatic Stress, and Alcohol Use for Bisexual Women(2019-12) King, Brooke; Smith, Nathan Grant; Reitzel, Lorraine R.; Liu, Yu; Tran, Jana K.Background: Lesbian, gay, and bisexual (LGB) individuals are at increased risk of both psychological distress (e.g., depression and anxiety) and maladaptive behaviors (e.g., alcohol use) compared to heterosexual peers. The literature linking discrimination experiences to symptoms of posttraumatic stress disorder (PTSD) suggests that sexual minority stress may serve as a form of posttraumatic stress. Studies addressing within-group differences indicate that bisexual women are more likely than other LGB people to report poor physical and psychological outcomes, which may be explained by disparities in social support and symptoms of posttraumatic stress. Purpose: The current study measured the role of social support and symptoms of posttraumatic stress as potential mediators in the relationship between discrimination experiences (anti-bisexual and sexist) and alcohol use in sample of bisexual women. Method: Participants included bisexual women over the age of 18 from an archival data set (N = 256) with measures including self-reported discrimination experiences, social support, posttraumatic symptoms, and alcohol use. Two sequential, three-path mediation path models were analyzed to examine the direct effects of anti-bisexual discrimination and sexist discrimination on alcohol use, as well as the indirect effects through social support and posttraumatic stress. Results: Path analyses were conducted to analyze the relationships between discrimination experiences, social support, PTSD symptoms, and alcohol use. Neither social support nor PTSD symptoms mediated the relationships between either anti-bisexual experiences or sexist experiences and alcohol use. Most effects were found to not be significant; however, significant bivariate relationships were found between anti-bisexual and sexist experiences, as well as between both types of discrimination experiences and PTSD symptoms. In addition, multivariate relationships were found between anti-bisexual experiences and PTSD symptoms; sexist experiences and PTSD symptoms; social support and PTSD symptoms; and sexist experiences and alcohol use. Conclusion: Anti-bisexual and sexist experiences appear linked, and both of these prejudice experiences relate to bisexual women’s reported PTSD symptoms. Future research should address the sequential relationships between these variables, as well as other psychosocial factors not explored in the present study. Clinicians are advised to conceptualize prejudice experiences as interrelated, and bisexual women clients would benefit from practice that is affirmative and trauma-informed.Item miR-322/503 Cluster Drives Cardiac Differentiation by Inhibiting CUG-binding Protein 1(2014-12) Shen, Xiaopeng 1990-; Schwartz, Robert J.; Liu, Yu; Gunaratne, Preethi H.; Widger, William R.; Cooney, Austin J.Understanding the mechanisms of early cardiac fate determination may lead to better approaches in promoting heart regeneration after injury. MicroRNAs (miRNAs) involved in the process are particularly interesting due to their small profile and relatively shorter path to clinic. With Mesp1 as the marker, we used a Mesp1-Cre/Rosa-EYFP reporter system to track the earliest cardiac progenitors, and identified the miRNAs enriched in these cells. Among them, the miR-322/503 cluster is found to be a powerful regulator of the cardiac program: (1) in a screening of more than 20 cardiac progenitor cell (CPC) enriched miRNAs, miR-322/503 was the most powerful in driving calcium flux activity in mouse embryonic stem cells (mESCs) differentiation; (2) induced ectopic expression of miR-322/503 to mimic the natural course in mESCs led to α-actinin expression and significant increases of cardiac transcription factors (Tbx5, Mef2C, Nkx2-5 and α-MHC); and (3) inhibitors of miR-322 and miR-503 significantly reduced expression of α-actinin and the above cardiac TFs. Remarkably, miR-322/503 regulates the cardiac program by inhibiting an RNA-alternative splicing/decay factor, CUG-binding protein 1 (Celf1), which is also known for a role in myotonic dystrophy pathogenesis. The evidences include: (i) miR-322 and miR-503 had a shared target site at the 3’UTR of Celf1; (ii) expression patterns of miR-322/503 and Celf1 were mutually exclusive, with the highest Celf1 expression in the brain; (iii) miR-322/503 repressed Celf1 protein expression in a dose-dependent manner; (iv) Celf1-shRNA induced up-regulation of cardiac transcription factors and α-actinin, mimicking the function of miR-322/503; and (v) the ectopic expression of Celf1 repressed expression of cardiac transcription factors, while promoted expressions of early neural markers, including Sox1, Notch3, Nestin and Pax6. In summary, we have identified a miR-322/503-Celf1 pathway that promotes cardiac differentiation by preventing activation of other lineages. This new regulatory mechanism may be used to direct cardiac regeneration after heart injury, and treat myotonic dystrophy where Celf1 up-regulation is responsible for skeletal muscle wasting and other symptoms.Item Novel Genetic/Chemogenetic Tools for Studying Beta-Adrenergic Receptors Biased Signaling in Heart Failure(2023-12) Rajaei, Mehrdad; McConnell, Bradley K.; Bond, Richard A.; Schwartz, Robert J.; Ruan, Ke-He; Liu, YuHeart failure (HF) is a chronic clinical condition, where the cardiac output is insufficient to meet the needs of the body. Currently, there are several standard pharmacological treatments of HF, most of which are associated with severe side effects, sometimes as detrimental as HF itself. G-protein coupled receptors (GPCRs) are the largest family of cell surface receptors. GPCRs can signal through multiple transducers, including G proteins and β-arrestins, and can be selectively activated in biased response. Cardiac contractility is tightly regulated by the activity of a group of GPCRs, known as Beta-adrenergic receptors. In a normal heart, β1- and β2-adrenoceptors play predominant roles in enhancing excitation-contraction coupling. For the β2AR, at least two signaling pathways have been characterized: the canonical Gαs pathway and the β-arrestin2 (βarr2) pathway. Despite recent advances in our understanding of β2AR biased signaling, much remains to be learned to develop novel therapeutics for the treatment of heart failure. We have designed β2AR-Gαs and β2AR-βarr2 fusion proteins and have shown that expression of these chimeras in AC-16 cells increases the constitutive activity of cAMP and ERK respectively. Our fusion proteins can dissect distinct mechanisms associated with β2AR-Gαs and β2AR-βarr2 signaling pathways and modulate the key regulators of calcium handling and contractile function. Alternatively, previous research has utilized a clozapine-N-oxide (CNO)-sensitive designer GPCR, to selectively induces βarr signaling. I generated and characterized a GPCR designer receptors exclusively activated by designer drugs (DREADD) that selectively binds to β-arrestins (βarr-DREADD). Overall, these experiments will help us to gain mechanistic and functional insight into biased β2AR signaling, and to assess the possibility of using designer GPCRs as a therapeutic approach in the treatment of HF.Item Reprogramming Cardiac Progenitor Cells into Pacemaker Cells for Heart Repair(2018-12) Raghunathan, Suchi; McConnell, Bradley K.; Schwartz, Robert J.; Bond, Richard A.; Zhang, Yang; Gunaratne, Preethi H.; Liu, YuSick sinus syndrome (SSS) is associated with the dysfunction of the sino atrial node (SAN), which is also the primary pacemaker of the heart. Dysfunction of the pacemaker prevents normal electrical conductivity, contributing to the recurrent development of the arrhythmias. Currently, electronic pacemaker implantation is the standard therapy for SSS and other cardiac rhythm disturbances. However, despite their clinical efficacy, they exhibit complications of infection, limited battery life, and lead fracturing. Hence, a therapy directed towards resorting normal electrical conductivity is of utmost clinical significance. This necessitates the need to generate biological pacemakers, which can integrate with the existing myocardium in a syncytium to enable synchronous beating of the heart without arrhythmias. In support of this concept, our objective was to use a unique cocktail of lentivirus- mediated transcription factors, that are critical to the embryonic development of the SAN for reprogramming cardiac progenitor cells (CPCs) into conducting Pacemaker-like cells. The CPCs treated with transcription factor combinations were initially screened for Pacemaker-like cells by FACS sorting for a reporter gene specific for pacemaker cells. Following which we assayed these cells for pacemaker marker genes. The results demonstrated a robust induction of Pacemaker marker genes in the SHOX2-HCN2-TBX5 (SHT5) activated CPCs by qPCR gene expression assays. Interestingly, the patch clamp recording of the Pacemaker-like cells exhibited funny currents (If) with a current density (pA/pF) of -5.03±1.36 (n=17). Further, we observed that the SHT5 cells (n=14) showed V1/2 of half of the maximal current (I/Imax at 0.5) as 125.28±3.83 mV, demonstrating the functional characteristic of pacemaker cells. Additionally, to expand our understanding of the transcriptome of SHT5 cells, we performed RNA sequencing and single cell sequencing of SHT5 mCherry+ cells. We observed that the transcriptome of SHT5 cells exhibited enrichment of pacemaker specific genes. In conclusion, SHOX2, HCN2 and TBX5 cocktail of transcription factors reprogrammed the CPCs into pacemaker-like cells. The SHT5 factors resulted in upregulation of pacemaker specific gene expression and the transcriptome, attributing pacemaker phenotype to the cells. These studies will facilitate the development of an optimal Pacemaker-like cell-based therapy within failing hearts through the recovery of lost contractile and electrical function between cardiomyocytes.Item Role of MicroRNA-424(322)/503 in Heart Disease(2021-12) Shrestha, Shreesti; Liu, Yu; Lin, Chin-Yo; McKeon, Frank D.; McConnell, Bradley K.Background: Cardiovascular disease is the topmost cause of death globally. Dilated cardiomyopathy (DCM), the most common cardiovascular diseases, is characterized by chamber dilation and systolic dysfunction eventually leading to heart failure. MicroRNAs have been shown to play an integral role in regulating the progression of cardiomyopathy and as a result have become novel targets for therapy. Previously, we found that miR-424(322)/503 is highly enriched in embryonic heart during early cardiac development but its expression drops to very low level after birth. Interestingly, other studies have revealed its upregulation in failing human hearts. However, the relation between miR-424(322)/503 and heart failure is not yet known. Methods and results: To understand the role of miR-424(322)/503 in the adult heart, we generated a tetracycline-controlled cardiomyocyte-specific miR-424(322)/503 expressing transgenic mice (TG). miR-424(322)/503 was induced in TG and wildtype (WT) mice (8 weeks) using doxycycline containing chow continuously for a month. The cardiac function was monitored every week. The tissues were harvested at the endpoint of the study for downstream analysis. We observed that the heart function of TG started deteriorating from 2 weeks of miR-424(322)/503 induction. Cardiac failure markers (ANP and BNP) were upregulated. Histology revealed dilated chambers with thin ventricular wall, presence of fibrosis and disorganized myocytes in TG, a phenotype consistent with DCM. We also observed that miR-424(322)/503-induced DCM progressed slowly with intermittent dose and even slower with lower dose of doxycycline. To further study the causative role, we removed the miR-424(322)/503 induction after 14 days and let them recover. We found that miR-424(322)/503-induced heart failure could be reversed by interrupting miR-424(322)/503 induction. RNA sequencing was done next to determine the genome-wide transcriptional changes. We observed several mitochondria-related genes and pathways to be downregulated. We also found mitochondrial dysregulation to be the common pathway between miR-424(322)/503-induced heart failure and human heart failure. Conclusion: Overall, this is the first study to show that upregulated miR-424(322)/503 in the heart is sufficient to lead to DCM and miR-424(322)/503-induced heart failure is reversible. We hypothesized that miR-424(322)/503-triggered DCM by dysregulating mitochondria. Thus, this study supports miR-424(322)/503 as a novel potential therapeutic target for DCM and heart failure.Item Synergistic Effect of Cardio-Stemin and YAP5SA Promotes Cardiomyocyte Regeneration in vivo(2020-12) Xiao, Siyu; Schwartz, Robert J.; Liu, Yu; Lin, Chin-Yo; Chang, JiangCardiovascular diseases are the leading cause of death worldwide. The fundamental goal of rescuing heart disease caused by loss or dysfunction of cardiomyocyte is to regain beating cardiomyocytes after injury. In this dissertation, we elucidated the synergistic effect of Stemin and YAP5SA in cardiomyocyte proliferation. More specifically, we focused on the potential of Stemin synergistically work with YAP5SA, inhibiting interactions between SRF and cardiac specific cofactors to inhibit SRF dependent cardiomyocyte differentiation, and promoting cell proliferation. Co-expression of Stemin and YAP5SA promoted EdU incorporation in both neonatal and adult cardiomyocyte. Adult cardiomyocytes were brought back into a putatively more primitive, fetal-like state for cell replication. Bioinformatic analysis revealed the upregulation of multiple cell cycle gene clusters with co-expression of Stemin and YAP5SA, while gene clusters associated with cardiomyocyte differentiation (GO: 0055007), sarcomeric assembly and cardiac muscle contraction (GO: 0060048) were profoundly downregulated. We also performed ATAC-seq in mRNA treated neonatal cardiomyocytes, which suggested a substantial increase of accessible chromatin region in mRNA treatment groups compared to the controls, indicating that Stemin and YAP5SA treatment may induce a global epigenetic change, which showed consistency with the RNA-seq results. We tested the treatment combination in vivo by injecting Stemin and YAP5SA mRNA directly into the left ventricles of adult mice after myocardial infarction. We were able to detect EdU incorporation around the needle tracts in the mRNA treatment groups, indicating promoted cell proliferation in response to Stemin and YAP5SA mRNA injection. Picrosirius Red staining also suggested reduced fibrosis. We further illustrated the improvement in mouse cardiac function in long-term experiments by echocardiography, demonstrating an ameliorated cardiac function by Stemin and YAP5SA mRNA co-injection. In conclusion, here we described a combination of factors that effectively induce cardiomyocyte proliferation both in vitro and in vivo. We revealed that the introduction of Stemin and YAP5SA synergistically promotes cardiomyocyte proliferation by inhibiting SRF dependent cardiomyocyte differentiation, thus pushing cardiomyocyte into a more primitive, stem cell-like stage to foster cell replication. Our findings suggested that inducing tissue renewal by Stemin and YAP5SA mRNA may be a useful strategy to treat degenerative human disease such as myocardial infarction.