C. ELEGANS HISTONE H2A VARIANTâ€™S TRANSCRIPTIONAL ROLE DURING SPERMATOGENESIS
Londen Johnson, Diana S. Chu.
San Francisco State University, San Francisco, CA.
One key contributor to fertility is proper sperm development. Sperm development is managed by the packaging of chromatin, composed of DNA wrapped around histone proteins. How tightly DNA is wrapped around histones can affect how accessible genes are for activation. Canonical histones are replaced by specialized variants, which assist in regulating chromatin structure. During sperm development, core histone H2A is replaced by variants HTZ-1 and HTAS-1. HTZ-1 is 54% identical to H2A, expressed in all cell types, and present at 23% of all Caenorhabditis elegans promoters. While HTZ-1 is present throughout the male germ line, HTAS-1 is incorporated into sperm chromatin during a period of global transcriptional silencing. Previous data shows that both variants co-localize with each other during later stages of spermatogenesis, a time when spermatids are highly compacted. Despite their presence in spermatogenesis, the transcriptional role of these histone variants is not fully known. Using the C. elegans model system, we will study the localization of these two variants with regards to active and inactive chromatin during spermatogenesis. We hypothesize that while HTZ-1 will aid in gene accessibility for transcription, HTAS-1 will assist in transcriptional silencing. In studying H2A histone variants in spermatogenesis, we can better understand their function in gene regulation and identify their unique role in fertility.