Histone Variant HTZ-1 as a Transcriptional Regulator of Germline Genes in C. elegans
By: Eric Tang and Nicholas Chu
Department: Cellular & Molecular Biology
Faculty Advisor: Dr. Diana Chu
The nematode Caenorhabditis elegans is a model organism that exists as either males or as hermaphrodites that possess the unique ability to self-fertilize. In the germlines of C. elegans hermaphrodites, mitotic germline stem cells are located at the distal tips of the gonad while mature gametes can be found near the gonad’s proximal end. During the L4 larval stage, meiotic germ cells at the proximal ends of the gonad undergo spermatogenesis, later switching to oogenesis as the organism develops into an adult. Whether germ cells differentiate into sperm or oocytes can be influenced by various epigenetic factors such as histones and histone variants. HTZ-1, a variant of the canonical histone H2A, has been previously found to target genes crucial for proper embryonic development as well as being implicated in the repression of genes in C. elegans. Here, we use RNA-Seq in conjunction with differential analysis to determine the role of HTZ-1 in spermatogenic and oogenic gene regulation. By comparing the expression profile of genes in htz-1 mutant hermaphrodite germlines to published data, we seek to identify the spermatogenic and oogenic genes that are potential regulatory targets of HTZ-1. A preliminary gene expression analysis of htz-1 mutant hermaphrodite germlines indicated a total of 6978 significantly expressed genes. Genes were labeled with the use of previously published gene lists that categorized genes as being spermatogenesis- or oogenesis-specific. While analysis of oogenic genes still continues, all of the spermatogenesis-specific genes identified in prior studies were found to be up-regulated in the htz-1 mutant, suggesting a repressive role for HTZ-1 in hermaphrodite spermatogenesis. Our results reveal additional potential targets of HTZ-1 in the C. elegans hermaphrodite germline and further elucidates the role of HTZ-1 in cell fate determination through regulating gene expression during spermatogenesis and oogenesis.