Protein Phosphatase 1 Down Regulates ZYG-1 Levels to Limit Centriole Duplication

In humans perturbations of centriole number are associated with tumorigenesis and microcephaly,therefore appropriate regulation of centriole duplication is critical. the c. elegans homolog of plk4,zyg-1,is required for centriole duplication,but our understanding of how zyg-1 levels are regulated remains incomplete. we have identified the two pp1 orthologs,gsp-1 and gsp-2,and their regulators i-2szy-2and sds-22 as key regulators of zyg-1 protein levels. we find that down-regulation of pp1 activity either directly,or by mutation of szy-2 or sds-22 can rescue the loss of centriole duplication associated with a zyg-1 hypomorphic allele. suppression is achieved through an increase in zyg-1 levels,and our data indicate that pp1 normally regulates zyg-1 through a post-translational mechanism. while moderate inhibition of pp1 activity can restore centriole duplication to a zyg-1 mutant,strong inhibition of pp1 in a wild-type background leads to centriole amplification via the production of more than one daughter centriole. our results thus define a new pathway that limits the number of daughter centrioles produced each cycle. © 2017 public library of science. all rights reserved.