DAF-18/PTEN and Germ Cell Quiescence

PTEN is one of the most frequently lost tumor suppressors in human cancers, and its activity regulates quiescence of stem cells and cancer cells. The sole PTEN ortholog in C. elegans is DAF-18.
 
Previous work in the field showed that in a C. elegans loss-of-function mutant for daf-18, primordial germ cells (PGCs) escape G2 arrest and divide inappropriately in L1 larvae hatched into starvation conditions, in a TOR-dependent manner.

We further investigated the role of daf-18 in maintaining PGC quiescence in L1 starvation. We found that maternal or zygotic daf-18 is sufficient to maintain cell cycle quiescence, that daf-18 acts in the germ line and in the soma, and that daf-18 also affects timing of PGC divisions in fed animals. Importantly, our results also implicate daf-18 in repression of germline zygotic gene activation, though not in germline fate specification. However, TOR appears to be less important to germline zygotic gene expression, suggesting that in the absence of food, DAF-18/PTEN prevents inappropriate germline zygotic gene activation and cell division by distinct mechanisms.

Relevant Publications

DAF-18/PTEN inhibits germline zygotic gene activation during primordial germ cell quiescence. Fry AL, Webster AK, Burnett J, Chitrakar R, Baugh LR, Hubbard EJA. PLoS Genet. 2021 Jul 21;17(7):e1009650. doi: 10.1371/journal.pgen.1009650. eCollection 2021 Jul. PMID: 34288923

Biology of the Caenorhabditis elegans Germline Stem Cell System. Hubbard EJA, Schedl T. Genetics. 2019 Dec;213(4):1145-1188. doi: 10.1534/genetics.119.300238. PMID: 31796552 Free PMC article. Review.