Browsing by Author "Zhang, Yang"
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Item Acid Sphingomyelinase Deficiency Prevents AdipoRon-induced Transcription Factor EB activation and Differentiation in Arterial Smooth Muscle Cells(2021-12) Zhao, Wei; Zhang, Yang; Ruan, Ke-He; McConnell, Bradley K.AdipoRon is a selective agonist of adiponectin receptor and has been reported to protect against vascular remodeling by preventing smooth muscle cell (SMC) dedifferentiation. Our recent studies have demonstrated that activation of transcription factor EB (TFEB) and its downstream autophagy signaling contribute to adipoRon-induced SMC dedifferentiation. This study aims to examine whether acid sphingomyelinase is involved in mediating adipoRon-induced TFEB activation in SMCs. In cultured arterial SMCs isolated from wild-type (Smpd1+/+) mice, adipoRon induced expression of acid sphingomyelinase (ASM; gene symbol Smpd1) and ceramide production, which is accompanied by TFEB nuclear translocation and upregulated transcription of genes involved in autophagy pathway and enhanced autophagic flux pathways. However, such adipoRon-induced ceramide, TFEB activation, and autophagic signaling were suppressed in SMCs from acid sphingomyelinase gene knockout (Smpd1-/-) mice. Consistently, adipoRon suppressed serum-induced cell proliferation and inhibited SMC migration in Smpd1+/+ SMCs as characterized by wound-healing retardation, F-actin reorganization, and matrix metalloproteinase-9 downregulation; whereas these inhibitory effects of adipoRon on proliferation and migration were attenuated in Smpd1-/- SMCs. Mechanistically, adipoRon increased the expression of protein phosphatase 2A (PP2A) and calcineurin in Smpd1+/+ SMCs but not Smpd1-/- SMCs. Pharmacological inhibition of PP2A by okadaic acid (OA) blocked adipoRon-induced TFEB activation and gene expression inSmpd1+/+ SMCs. Furthermore, activation of calcineurin by lysosomal TRPML1 channel agonist ML-SA1 could similarly activate TFEB and downstream autophagic signaling in Smpd1+/+ and Smpd1-/- SMCs. Inhibiting calcineurin by FK506 and cyclosporin A (CsA) prevented AdipoRon-induced TFEB and autophagy signaling activation. Together, these data suggest that adipoRon-induced TFEB signaling in SMCs is dependent on the ASM-mediated activation of phosphatase PP2A and calcineurin. This study provides novel mechanistic insights into understanding the therapeutic effects of adipoRon on TFEB signaling and pathological vascular remodeling.Item An Investigation into the Role of 27-Hydroxycholesterol and Estrogen Receptors in Adipose Tissue, Obesity, and Breast Cancer(2021-05) Asghari Khonakdari, Arvand; Umetani, Michihisa; Xu, Yong; Zhang, Yang; Dauwalder, Brigitte; Chung, Sang-HyukObesity is an emerging health crisis all over the world. With obesity comes several other health disorders such as type-2 diabetes, cardiovascular diseases, and cancers. Hence, understanding the underlying reasons for obesity is of paramount importance as it can guide us in developing new therapeutic approaches for preventing or decreasing the obesity rates. Breast cancer is the second cause of cancer-related deaths among women worldwide. Endocrine resistance in breast cancer which occurs after endocrine therapies, causes the tumors to relapse after years of dormancy. While estrogen receptors (ERs) mutations and malfunctions of other signaling pathways (e.g., MAPK signaling) are some of the underlying reasons for endocrine resistance in breast cancer, the underlying causes of 60% of endocrine resistance cases remain completely unknown. Estrogen and estrogen receptors play important roles in both obesity and breast cancer. 27-Hydroxycholesterol (27HC), the first identified endogenous selective estrogen receptor modulator, can modulate the activity of estrogen receptors in different tissues and thus can be one of the important factors in regulating the functions of ERs in the context of obesity and breast cancer. In this dissertation, I first showed that 27HC mostly works as an antagonist for ERs activity in different tissues. Next, I investigated the effects of 27HC on adipose tissues and obesity. My research showed that 27HC increases body weight gain in the presence of a high-fat, high- cholesterol diet in an ER-dependent manner. Moreover, 27HC increases body fat percentage regardless of the diet and affects adipose tissue gene expression and induces inflammation in the adipose tissue. I also showed that 27HC alters the morphology and function of brown adipose tissue. In regard to endocrine resistance in breast cancer, I showed that 27HC increases the growth rate of the endocrine-resistant breast cancer cells, and I also found a novel group of genes that can be the underlying reasons for the endocrine development and progression. All in all, the research presented in this dissertation confirms the importance of 27HC in obesity and breast cancer and opens new doors toward the development of potential therapeutics to decrease the obesity rates, as well as treatment of endocrine-resistant breast cancer.Item CELLULAR AND MOLECULAR MECHANISMS OF AT2R MEDIATED ANTI-PROTEINURIC ACTIVITY(2023-07-08) Kulkarni, Kalyani; Hussain, Tahir; McConnell, Bradley K.; Zhang, Yang; Mani, Shailaja K.; Oyekan, Adebayo O.Proteinuria is a sensitive and specific biomarker of and a cause for kidney diseases. Immediate effects upon consumption of high sodium (4%) diet (HSD) on the expression of protein endocytic receptor megalin and its impact on proteinuria, particularly in obesity is not known. There are indications suggesting the involvement of glycogen synthase kinase (GSK)-3β-mediated megalin phosphorylation, and its subsequent endocytosis and lysosomal degradation resulting in proteinuric kidney injury. Present study reports that acute treatment with angiotensin-II type 2 receptor (AT2R) agonist C21 rescues megalin surface expression in the proximal tubules potentially by activating Akt-mediated phosphorylation and inactivation of GSK3β in the kidney of male obese Zucker rats fed HSD for 48 hrs. The HSD intake resulted in proteinuria, which was significantly prevented by C21. Moreover, the expression of glomerular slit diaphragm proteins (nephrin and podocin) the estimated glomerular filtration rate remained unaffected which together suggest that HSD intake caused tubular proteinuria. The in vivo findings in megalin recycling impairment were confirmed by the in vitro studies performed in Opossum Kidney (OK) cells which are the proximal tubule epithelial cells treated with high NaCl (100 mM) without/with C21. Compared to control, high NaCl reduced megalin surface expression, which is protected by C21 treatment. AT2R activation by C21 in OK cells treated with high NaCl increased Akt phosphorylation which was attenuated by AT2R antagonist PD123319 suggesting role of AT2R. Moreover, GSK3 inhibitor SB216763 reversed the effect of high NaCl on megalin surface expression, suggesting role in GSK3-induced disruption in megalin expression. However, Akt and PP2A inhibitors did not inhibit the effects of C21 on megalin rescue. FITC albumin uptake assay, which is a functional measure of megalin, revealed that HS caused reduction in albumin uptake which was prevented by C21 treatment. Moreover, GSK3 inhibitor restored albumin uptake. Akt inhibitor attenuated C21 mediated protection in megalin function. Overall, high NaCl induces proteinuria by disrupting cell surface megalin expression, potentially via Akt-mediated phosphorylation and a decrease in GSK3 phosphorylation. AT2R activation protects megalin cell surface expression and reverses proteinuria, via potentially reducing GSK3 activity.Item Inhibitor of the Tyrosine Phosphatase STEP Reverses Cognitive Deficits in a Mouse Model of Alzheimer’s Disease(PLoS Biology, 2014-08) Xu, Jian; Chatterjee, Manavi; Baguley, Tyler D.; Brouillette, Jonathan; Kurup, Pradeep; Ghosh, Debolina; Kanyo, Jean; Zhang, Yang; Seyb, Kathleen I.; Ononenyi, Chimezie; Foscue, Ethan; Anderson, George M.; Gresack, Jodi; Cuny, Gregory D.; Glicksman, Marcie A.; Greengard, Paul; Lam, TuKiet T.; Tautz, Lutz; Nairn, Angus C.; Ellman, Jonathan A.; Lombroso, Paul J.STEP (STriatal-Enriched protein tyrosine Phosphatase) is a neuron-specific phosphatase that regulates N-methyl-D-aspartate receptor (NMDAR) and ?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) trafficking, as well as ERK1/2, p38, Fyn, and Pyk2 activity. STEP is overactive in several neuropsychiatric and neurodegenerative disorders, including Alzheimer's disease (AD). The increase in STEP activity likely disrupts synaptic function and contributes to the cognitive deficits in AD. AD mice lacking STEP have restored levels of glutamate receptors on synaptosomal membranes and improved cognitive function, results that suggest STEP as a novel therapeutic target for AD. Here we describe the first large-scale effort to identify and characterize small-molecule STEP inhibitors. We identified the benzopentathiepin 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (known as TC-2153) as an inhibitor of STEP with an IC50 of 24.6 nM. TC-2153 represents a novel class of PTP inhibitors based upon a cyclic polysulfide pharmacophore that forms a reversible covalent bond with the catalytic cysteine in STEP. In cell-based secondary assays, TC-2153 increased tyrosine phosphorylation of STEP substrates ERK1/2, Pyk2, and GluN2B, and exhibited no toxicity in cortical cultures. Validation and specificity experiments performed in wild-type (WT) and STEP knockout (KO) cortical cells and in vivo in WT and STEP KO mice suggest specificity of inhibitors towards STEP compared to highly homologous tyrosine phosphatases. Furthermore, TC-2153 improved cognitive function in several cognitive tasks in 6- and 12-mo-old triple transgenic AD (3xTg-AD) mice, with no change in beta amyloid and phospho-tau levels.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 VITAMIN D SUPPRESSES CANCER GROWTH AND INVASION BY TARGETING LONG NON-CODING RNA CCAT2(2021-05) Wang, Liye; Guo, Bin; Chow, Diana Shu-Lian; Johnson, Michael L.; Zhang, Yang; Liu, JinsongCalcitriol (1 alpha, 25-dihydroxy vitamin D3, 1α,25-(OH)2D3), the most active metabolite of vitamin D (VD), protects against various types of cancers. Preclinical studies have presented that calcitriol suppresses cancer growth in a cell- and tissue-specific manner. Here, our study determined that the anti-growth and anti-invasion effects of calcitriol in ovarian cancer (Oca) and colon cancer (CRC) cells. Moreover, previous studies suggested that calcitriol may exhibit genomic effects on both protein-coding genes and non-coding genes. However, the epigenetic mechanisms of calcitriol’s anti-cancer effects remain largely unknown as its downstream targets or signaling pathways are poorly identified. To explore the potential epigenetic mechanism of vitamin D, we investigated the effects of calcitriol on long noncoding RNA (lncRNA) expression profiles in ovarian and colon cancer cells. We firstly identified that calcitriol could regulate specific lncRNAs and the corresponding downstream pathways in its cancer-preventive action. In our study, we illustrated that (a) Treatment with calcitriol inhibited ovarian and colon cancer cell proliferation, migration, and invasion; (b) calcitriol induced cell cycle arrest in a cell-specific manner; (c) lncRNA CCAT2 (colon cancer-associated transcript 2) is significantly down-regulated in the presence of calcitriol in ovarian and colon cancer cells; (d) lncRNA CCAT2 exerted a regulatory potential on MYC gene expression; (e) calcitriol inhibited the physical interaction of CCAT2 and its downstream transcription factor TCF4; (f) As a result of CCAT2 inhibition, the binding of CCAT2:TCF4 ribonucleoprotein to the MYC promoter was suppressed at the action of calcitriol, resulting in the repression of MYC expression. Our results offered a novel mechanism in vitamin D-mediated anti-cancer activities by targeting lncRNA CCAT2. Colon tumor xenografts studies supported the results of in vitro studies that calcitriol inhibited CCAT2 expression and, consequently caused a decrease in c-Myc (encoded by MYC) expression. Our findings strongly suggested that vitamin D could be considered as a practical and inexpensive nutraceutical for cancer prevention and treatment.Item When Mobile Blockchain Meets Edge Computing: Challenges and Applications(IEEE Communications Magazine, 8/14/2018) Xiong, Zehui; Zhang, Yang; Niyato, Dusit; Wang, Ping; Han, ZhuBlockchain, as the backbone technology of the current popular Bitcoin digital currency, has become a promising decentralized data management framework. Although blockchain has been widely adopted in many applications (e.g., finance, healthcare, and logistics), its application in mobile services is still limited. This is due to the fact that blockchain users need to solve preset proof-of-work puzzles to add new data (i.e., a block) to the blockchain. Solving the proof of work, however, consumes substantial resources in terms of CPU time and energy, which is not suitable for resource-limited mobile devices. To facilitate blockchain applications in future mobile Internet of Things systems, multiple access mobile edge computing appears to be an auspicious solution to solve the proof-of-work puzzles for mobile users. We first introduce a novel concept of edge computing for mobile blockchain. Then we introduce an economic approach for edge computing resource management. Moreover, a prototype of mobile edge computing enabled blockchain systems is presented with experimental results to justify the proposed concept.