A WHOLE EMBRYONIC SINGLE-CELL MODEL FOR OCULOCUTANEOUS ALBINISM TYPE II SUGGESTS A PH-SWITCHED TRANSCRIPTIONAL MECHANISM FOR KEY GENES REGULATING CELL FATE

Taylor M. Krilanovich

doi:10.7273/000006946

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A WHOLE EMBRYONIC SINGLE-CELL MODEL FOR OCULOCUTANEOUS ALBINISM TYPE II SUGGESTS A PH-SWITCHED TRANSCRIPTIONAL MECHANISM FOR KEY GENES REGULATING CELL FATE

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A WHOLE EMBRYONIC SINGLE-CELL MODEL FOR OCULOCUTANEOUS ALBINISM TYPE II SUGGESTS A PH-SWITCHED TRANSCRIPTIONAL MECHANISM FOR KEY GENES REGULATING CELL FATE

Taylor M. Krilanovich

Washington State University

Master of Science (MS), Washington State University

05/2024

DOI:

https://doi.org/10.7273/000006946

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Abstract

acp1

Albinism

Occulocutanous Albinism

Pigment

scRNA Sequencing

Zebrafish

Molecular Biology

Oculocutaneous Albinism Type II (OCA2) is a non-syndromic pigment disorder associated with pathogenic variants of the OCA2 gene. OCA2 encodes a membrane-spanning active transport protein essential for pH regulation and substrate trafficking in melanosomes, the organelle in which the black pigment melanin is made. Humans with OCA2 exhibit near-total loss of melanin in their hair, skin and eyes, alongside poorly understood developmental side effects, including underdeveloped and misrouted ocular sensory and motor neurons. Using a novel zebrafish mutant as a disease model for OCA2 in humans, we have created the first whole-embryonic single cell transcriptomic atlas for this condition. The oca2 mutant zebrafish exhibits abnormal number and location of iridophores, an accessory pigment cell type found in fish and amphibians. This suggests that the oca2 protein or transcript is involved in the determination of non-melanocyte cell fate within the neural crest lineage, the transient population of multipotent stem cells from which pigment cells are derived. Single cell transcriptomic analysis of the mutant revealed alterations of several gene networks involved in neural crest differentiation and specification. Notably, acp1 and ctnnb1/2 exhibited significant negative log fold change values in the neural crest. acp1, a protein tyrosine phosphatase involved in melanogenesis, is also a positive effector for transcription of beta catenin (ctnnb1/2). Beta catenin-dependent pathways Notch and Wnt were obstructed in neural crest, neural plate, and optic nerve cell populations, consistent with downstream abnormalities to non-melanocyte cell fate and number observed in the oca2 mutant. Transcription of acp1 is also known to be strongly inhibited by increases in extracellular pH. Based on this information we propose that oca2 prevents pH- dependent repression of acp1 transcription by maintaining the intracellular H+ gradient. This project is supported by the NIH (grant number R03HD103609).

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Title: A WHOLE EMBRYONIC SINGLE-CELL MODEL FOR OCULOCUTANEOUS ALBINISM TYPE II SUGGESTS A PH-SWITCHED TRANSCRIPTIONAL MECHANISM FOR KEY GENES REGULATING CELL FATE
Creators: Taylor M. Krilanovich
Contributors: Cynthia Cooper (Chair)
Ryan Driskell (Committee Member)
Eric Shelden (Committee Member)
Awarding Institution: Washington State University
Academic Unit: School of Molecular Biosciences
Theses and Dissertations: Master of Science (MS), Washington State University
Publisher: Washington State University
Number of pages: 48
Identifiers: 99901125038801842
Language: English
Resource Type: Thesis