Function and Regulation of the Conserved Wnt Target sp5 in the Vertebrate Nervous System

dc.contributor.advisorLekven, Arne C.
dc.contributor.committeeMemberAlward, Beau A.
dc.contributor.committeeMemberDauwalder, Brigitte
dc.contributor.committeeMemberLin, Chin-Yo
dc.creatorMohanty, Saurav
dc.date.accessioned2024-01-26T19:37:12Z
dc.date.createdDecember 2023
dc.date.issued2023-12
dc.date.updated2024-01-26T19:37:13Z
dc.description.abstractWnt/β-catenin signaling culminates in the transcriptional regulation of target genes. Target genes mediate Wnt function during different developmental processes. A dysfunctional Wnt/β-catenin signaling results in aberrant regulation of the target genes that often causes developmental malformations and cancer. In order to understand how Wnt signaling regulates development and diseases, identification of its downstream network of transcriptional targets and their subsequent roles is required. sp5 gene is a target of Wnt signaling in several vertebrates and invertebrates including humans, Xenopus, Mouse, zebrafish, Hydra and amphioxus. Despite the evidence of its involvement in Wnt mediated processes in several species, its regulation and exact function during Wnt mediated nervous system patterning is not well studied. Here we show that during neural patterning, Wnt/β-catenin signaling regulates the transcription of 3 Sp-family genes in zebrafish: sp5a, sp5-like (sp5l) and sp8b. These 3 genes are expressed in the neural plate during embryogenesis. I generated single and double loss of function genetic mutants for sp5a and sp5l that do not exhibit any observable phenotypic defects during development. However, sp5a, sp5l and sp8b triple knockdown embryos display hindbrain and posterior body defects, indicating that sp8b acts redundantly with the sp5a and sp5l to regulate early development and patterning. I examined the regulation of sp5a by Wnt and FGF in transgenic reporter lines to show that the promoter of sp5a is responsive to modulation in Wnt and FGF signaling levels. De-repression by Wnt followed by activation by FGF signaling is required for the expression of sp5a in the neural plate during embryonic development. Furthermore, I showed that sp5a is expressed in the adult habenula and regulates the expression of the habenular progenitor marker gene dbx1b. RNA sequencing reveals significant downregulation of dbx1b in sp5a loss of function mutants. Comparison of wild-type and mutant sp5a reporter lines suggests that the sp5a expression in the habenula is regulated by Wnt signaling. This data suggests a potential role of sp5a in habenula neurogenesis, downstream of Wnt signaling, through the regulation of dbx1b.
dc.description.departmentBiology and Biochemistry, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.citationPortions of this document appear in: Green, David G., Amy E. Whitener, Saurav Mohanty, Brandon Mistretta, Preethi Gunaratne, Alvin T. Yeh, and Arne C. Lekven. 2020. “Wnt Signaling Regulates Neural Plate Patterning in Distinct Temporal Phases with Dynamic Transcriptional Outputs.” Developmental Biology 462 (2): 152–64; and in: Tan, A. L., Mohanty, S., Guo, J., Lekven, A. C., & Riley, B. B. (2022). Pax2a, Sp5a and Sp5l act downstream of Fgf and Wnt to coordinate sensory-neural patterning in the inner ear. Developmental biology, 492, 139–153.
dc.identifier.urihttps://hdl.handle.net/10657/16192
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectsp5 gene, nervous system patterning, Wnt/β-catenin signaling
dc.titleFunction and Regulation of the Conserved Wnt Target sp5 in the Vertebrate Nervous System
dc.type.dcmitext
dc.type.genreThesis
dcterms.accessRightsThe full text of this item is not available at this time because the student has placed this item under an embargo for a period of time. The Libraries are not authorized to provide a copy of this work during the embargo period.
local.embargo.lift2025-12-01
local.embargo.terms2025-12-01
thesis.degree.collegeCollege of Natural Sciences and Mathematics
thesis.degree.departmentBiology and Biochemistry, Department of
thesis.degree.disciplineBiology
thesis.degree.grantorUniversity of Houston
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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