emb-4 is a Conserved Gene Required for Efficient Germline-Specific Chromatin Remodeling during Caenorhabditis elegans Embryogenesis

IIn C. elegans, germline blastomeres are initially kept transcriptionally quiescent by the maternally loaded CCCH zinc-finger protein PIE-1. PIE-1 disappears upon the birth of the primordial germ cells Z2 and Z3, yet these cells appear to remain quiescent. We have previously demonstrated that there is a chromatin-based repression that succeeds PIE-1 degradation. The chromatin in Z2/Z3 loses certain histone modifications including histone H3 lysine 4 dimethylation (H3K4me2), a conserved marker for transcriptionally competent chromatin. We find that mutations in the maternal effect gene emb-4 cause defects in both PIE-1 degradation and in germline-specific chromatin remodeling. emb-4 encodes a highly conserved protein with orthologs in fly, mouse, and human and has a subtle role in Notch signaling (KATIC and GREENWALD, accompanying manuscript). The embryonic phenotype of emb-4 is consistent with a defect in the efficient and timely activation of developmental programs, including germline chromatin remodeling. We also find that, as in early somatic blastomeres, the degradation of PIE-1 in Z2/Z3 is facilitated by zinc finger-interacting protein ZIF-1, and in the absence of either zif-1 or emb-4 PIE-1 is abnormally retained in Z2/Z3.

Key Words: C. elegans, chromatin, embryogenesis, epigenetics, germline

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				I. Katic and I. Greenwald EMB-4: A Predicted ATPase That Facilitates lin-12 Activity in Caenorhabditis elegans Genetics, December 1, 2006; 174(4): 1907 - 1915. [Abstract] [Full Text] [PDF]

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