New Insights into the Regulation of RNP Granule Assembly in Oocytes

Abstract

In a variety of cell types in plants, animals, and fungi, ribonucleoprotein (RNP) complexes play critical roles in regulating RNA metabolism. These RNP granules include processing bodies and stress granules that are found broadly across cell types, as well as RNP granules unique to the germline, such as P granules, polar granules, sponge bodies, and germinal granules. This review focuses on RNP granules localized in oocytes of the major model systems, Caenorhabditis elegans, Drosophila, Xenopus, mouse, and zebrafish. The signature families of proteins within oocyte RNPs include Vasa and other RNA-binding proteins, decapping activators and enzymes, Argonaute family proteins, and translation initiation complex proteins. This review describes the many recent insights into the dynamics and functions of RNP granules, including their roles in mRNA degradation, mRNA localization, translational regulation, and fertility. The roles of the cytoskeleton and cell organelles in regulating RNP granule assembly are also discussed.

A developmentally regulated translational control pathway establishes the meiotic chromosome segregation pattern

“…Thus, Rim4 is an ideal candidate for assembling into non-membrane-bound RNP structures. RNP structures, including P-bodies, P-granules, and germ granules, have been described in germ cells of many animal species and shown to regulate the translation of key regulators of germ cell development and early embryonic patterning (Schisa 2012). Our results indicate that translational control of mRNAs is a much more widespread regulatory tool in germ cell development than previously appreciated and is perhaps an ancient and integral aspect of the evolution of sexual reproduction.…”

The P granule component PGL-1 promotes the localization and silencing activity of the PUF protein FBF-2 in germline stem cells

“…A role for P granules in mRNA regulation has been suggested ever since their discovery as RNA-rich structures (reviewed by Voronina et al, 2011;Schisa, 2012). Our data demonstrate that PGL-1 facilitates translational silencing by FBF-2, but this is unlikely to be the only role of PGL-1.…”

The Crystal Structure of the Drosophila Germline Inducer Oskar Identifies Two Domains with Distinct Vasa Helicase- and RNA-Binding Activities

“…Residues involved in dimerization (green inverted triangle) of the Drosophila Oskar (legend continued on next page) upon which the germ plasm is assembled, by stepwise recruitment of other components. Although the oskar gene is only present in some insects, germ plasm has been described in many species (Juhn and James, 2006;Juhn et al, 2008;Lynch et al, 2011, Ewen-Campen et al, 2012Voronina et al, 2011;Schisa, 2012). In Danio rerio, Bucky ball, and in C. elegans, PGL-1 and PGL-3 have been shown to have central roles in germ plasm formation (Marlow and Mullins, 2008;Bontems et al, 2009;Updike and Strome, 2010).…”