Ethan Lee
Faculty Member
Last active: 7/23/2019

TRIP/NOPO E3 ubiquitin ligase promotes ubiquitylation of DNA polymerase η.

Wallace HA, Merkle JA, Yu MC, Berg TG, Lee E, Bosco G, Lee LA
Development. 2014 141 (6): 1332-41

PMID: 24553286 · PMCID: PMC3943184 · DOI:10.1242/dev.101196

We previously identified a Drosophila maternal effect-lethal mutant named 'no poles' (nopo). Embryos from nopo females undergo mitotic arrest with barrel-shaped, acentrosomal spindles during the rapid cycles of syncytial embryogenesis because of activation of a Chk2-mediated DNA checkpoint. NOPO is the Drosophila homolog of human TNF receptor associated factor (TRAF)-interacting protein (TRIP), which has been implicated in TNF signaling. NOPO and TRIP contain RING domains closely resembling those of known E3 ubiquitin ligases. We herein sought to elucidate the mechanism by which TRIP/NOPO promotes genomic stability by performing a yeast two-hybrid screen to identify potential substrates/interactors. We identified members of the Y-family of DNA polymerases that facilitate replicative bypass of damaged DNA (translesion synthesis) as TRIP interactors. We show that TRIP and NOPO co-immunoprecipitate with human and Drosophila Polη, respectively, from cultured cells. We generated a null mutation in Drosophila Polη (dPolη) and found that dPolη-derived embryos have increased sensitivity to ultraviolet irradiation and exhibit nopo-like mitotic spindle defects. dPolη and nopo interact genetically in that overexpression of dPolη in hypomorphic nopo-derived embryos suppresses nopo phenotypes. We observed enhanced ubiquitylation of Polη by TRIP and NOPO E3 ligases in human cells and Drosophila embryos, respectively, and show that TRIP promotes hPolη localization to nuclear foci in human cells. We present a model in which TRIP/NOPO ubiquitylates Polη to positively regulate its activity in translesion synthesis.

MeSH Terms (20)

Active Transport, Cell Nucleus Animals Animals, Genetically Modified DNA-Directed DNA Polymerase DNA Damage Drosophila melanogaster Drosophila Proteins Female Gene Expression Regulation, Developmental Gene Expression Regulation, Enzymologic Genomic Instability HeLa Cells Humans Models, Biological Mutation Signal Transduction Tumor Necrosis Factor Receptor-Associated Peptides and Proteins Two-Hybrid System Techniques Ubiquitin-Protein Ligases Ubiquitination

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