The 14-3-3 genepar-5is required for germline development and DNA damage response inCaenorhabditis elegans.

Abstract

Summary 14-3-3 proteins have been extensively studied in organisms ranging from yeast to mammals and are associated with multiple roles, including fundamental processes such as the cell cycle, apoptosis and the stress response, to diseases such as cancer. In Caenorhabditis elegans, there are two 14-3-3 genes, ftt-2 and par-5. ftt-2 is expressed only in somatic lineages, whereas par-5 expression is detected in both soma and germline. During early embryonic development, par-5 is necessary to establish cell polarity. Although it is known that par-5 inactivation results in sterility, the role of this gene in germline development is poorly characterized. In the present study, we used a par-5 mutation and RNA interference to characterize par-5 functions in the germline. The lack of par-5 in germ cells caused cell cycle deregulation, the accumulation of endogenous DNA damage and genomic instability. Moreover, par-5 was required for checkpointinduced cell cycle arrest in response to DNA-damaging agents. We propose a model in which PAR-5 regulates CDK-1 phosphorylation to prevent premature mitotic entry. This study opens a new path to investigate the mechanisms of 14-3-3 functions, which are not only essential for C. elegans development, but have also been shown to be altered in human diseases.

The 14-3-3 protein PAR-5 regulates the asymmetric localization of the LET-99 spindle positioning protein

“…Thus, these observations suggest that distinct mechanisms regulate the cortical inhibition of LET-99 at the anterior versus the posterior poles. Because 14-3-3 protein typically bind phosphorylated targets (reviewed in (Aristizabal-Corrales et al, 2012; Gardino and Yaffe, 2011; Obsil and Obsilova, 2011), the results reported here and in previous studies (Wu and Rose, 2007) support a model in which LET-99 is phosphorylated on 14-3-3 sites in the posterior by PAR-1 or a kinase downstream of PAR-1. Phosphorylated LET-99 then associates with PAR-5, which prevents LET-99's accumulation at the posterior-most cortex.…”

“…Strong reduction in PAR-5 levels results in germ-line defects and sterility (Aristizabal-Corrales et al, 2012; Wang and Shakes, 1997). However defects in one-cell polarity can be observed in embryos derived from mothers with a partial loss of PAR-5 function generated by RNA interference (RNAi) or the use of maternal specific alleles (Morton et al, 2002).…”

“…A requirement for 14-3-3 binding sites has also been demonstrated for Exuperentia, a target of PAR-1 in Drosophila oocyte asymmetry; however, direct binding of the PAR-5/14-3-3 protein to Exuperentia was not examined (Riechmann and Ephrussi, 2004). 14-3-3 proteins are known to coordinately regulate multiple proteins involved in a given process, such as cell proliferation or apoptosis (Aristizabal-Corrales et al, 2012; Gardino and Yaffe, 2011). Thus, given our work on LET-99 and the two cases cited above, it will be interesting to determine if PAR-1 and PKC-3 regulate other downstream targets in asymmetric division via 14-3-3 interactions.…”

“…14-3-3 proteins are involved in many different processes, but in general they act via binding to phosphorylated targets to alter their subcellular localization, activity, or stability (reviewed in (Aristizabal-Corrales et al, 2012; Gardino and Yaffe, 2011; Obsil and Obsilova, 2011). In several systems including C. elegans (Morton et al, 2002), orthologs of PAR-5 are required for the mutual exclusion of the PAR proteins from their reciprocal domains.…”

Identification of regulators of germ stem cell enwrapment by its niche in C. elegans

“…SAGE analysis has indicated that these genes are expressed in dissected gonads, though multiple somatic gonad cells including the DTC are present in this sample (Xin Wang et al, 2009). Notably, pab-1 , W07E6.2, and par-5 have reported roles in germ cell proliferation (Aristizábal-Corrales et al, 2012; Ko et al, 2010; Voutev et al, 2006). Germline-expression profiling previously showed that his-72 , ran-1 , W07E6.2, and snr-2 are enriched in wild-type animals compared to germline-depleted mutants (Reinke et al, 2004), suggesting that these genes are expressed in the germline.…”