The DAZL and PABP families: RNA-binding proteins with interrelated roles in translational control in oocytes

Abstract

Gametogenesis is a highly complex process that requires the exquisite temporal, spatial and amplitudinal regulation of gene expression at multiple levels. Translational regulation is important in a wide variety of cell types but may be even more prevalent in germ cells, where periods of transcriptional quiescence necessitate the use of post-transcriptional mechanisms to effect changes in gene expression. Consistent with this, studies in multiple animal models have revealed an essential role for mRNA translation in the establishment and maintenance of reproductive competence. While studies in humans are less advanced, emerging evidence suggests that translational regulation plays a similarly important role in human germ cells and fertility. This review highlights specific mechanisms of translational regulation that play critical roles in oogenesis by activating subsets of mRNAs. These mRNAs are activated in a strictly determined temporal manner via elements located within their 3 0 UTR, which serve as binding sites for trans-acting factors. While we concentrate on oogenesis, these regulatory events also play important roles during spermatogenesis. In particular, we focus on the deleted in azoospermia-like (DAZL) family of proteins, recently implicated in the translational control of specific mRNAs in germ cells; their relationship with the general translation initiation factor poly(A)-binding protein (PABP) and the process of cytoplasmic mRNA polyadenylation.

Epab and Pabpc1 are differentially expressed in the postnatal mouse ovaries

“…As is well known, meiosis in mouse oocytes begins at around embryonic day 13.5 and it is arrested at diplotene stage of meiosis I [23,24]. These findings suggest Fig.…”

Deleted in Azoospermia-Like Enhances In Vitro Derived Porcine Germ Cell Formation and Meiosis

“…DAZL is known to interact with poly(A)-binding proteins (PABPs) in vivo [26]. It has been proposed that DAZL binds to a 3¢UTR and thereby recruits PABP, which in turn interacts with 5¢ end-associated factors to enhance translation [27]. In our study, the levels of SCP3 and VASA (Mvh) were both significantly upregulated in our PLCs.…”

RNA-binding proteins, RNA granules, and gametes: is unity strength?

“…Upon resumption of meiosis, SCAs disintegrated, thus releasing maternal mRNAs that become available for translation or degradation. The first wave of mRNA degradation takes place concomitantly owing in part to modifications of the length of their polyA tail (Richter 2007, Brook et al 2009, Zuccotti et al 2011 and to the upregulation of DCP1A expression . PBs remain absent in pre-implantation embryos until the morula stage.…”

“…Inhibition or activation of translation relies on cis-acting elements usually located in the 3 0 -UTR of mRNAs and the small RNAs and RBPs with which they interact (reviewed in Vasudevan et al (2006), Brook et al (2009) andMacNicol &MacNicol (2010)). The roles of specific RBPs in these processes, in particular CPEB, PABP, Pumilio2, or Musachi, have been well studied in Xenopus (reviewed in Vasudevan et al (2006) and MacNicol & MacNicol (2010)).…”

“…This post-transcriptional regulatory cascade leads to a progressive accumulation of DAZL, which in turn promotes the translation of DAZL target mRNAs, including Tpx2, Tex19.1, and other regulators of the cell cycle necessary for spindle assembly, the MI-MII transition, and early embryonic development (Chen et al 2011). In addition, DAZL is known to interact with several other proteins, including Pumilio2 that may act as a translational repressor (Vasudevan et al 2006, Brook et al 2009, MacNicol & MacNicol 2010. Understanding more precisely how these proteins interplay and whether their activity is compartmentalized in the cytoplasm remains to be investigated, even though some data are already available.…”