DDX6 belongs to the DEAD box family of putative RNA helicases that contain a characteristic asp-glu-ala-asp (DEAD) box motif (Seto et al., 1995). DDX6 localizes to cytoplasmic processing bodies (P bodies) involved in mRNA storage, processing, regulation, and degradation and is required for P-body formation (Scheller et al., 2007).
General function
Enzyme, RNA binding
Comment
P-Body Loss Is Concomitant with Formation of a Messenger RNA Storage Domain in Mouse Oocytes. Flemr M et al. In mammalian somatic cells, several pathways converge on deadenylation, decapping, and 5'-3' degradation in cytoplasmic foci known as P-bodies. Because controlled mRNA stability is essential for oocyte-to-zygote transition, we examined dynamics of P-body components in mouse oocytes. We report that oocyte growth is accompanied by loss of P-bodies and a sub-cortical accumulation of several RNA-binding proteins, including DDX6, CPEB, YBX2 (MSY2), and the exon junction complex. These proteins form transient, RNA-containing aggregates in fully-grown oocytes with a surrounded nucleolus chromatin configuration. These aggregates disperse during oocyte maturation, consistent with recruitment of maternal mRNAs that occurs during this time. In contrast, levels of DCP1A are low during oocyte growth and DCP1A does not co-localize with DDX6 in the sub-cortical aggregates. The amount of DCP1A markedly increases during meiosis, which correlates with the first wave of destabilization of maternal mRNAs. We propose that the cortex of growing oocytes serves an mRNA storage compartment, which contains a novel type of RNA granule related to P-bodies.
Cellular localization
Nuclear
Comment
Ovarian function
Follicle endowment, Oogenesis
Comment
Expression regulated by
Comment
Ovarian localization
Oocyte
Comment
Expression of rck/p54, a DEAD-box RNA helicase, in gametogenesis and early embryogenesis of mice Matsumoto K,et al .
Gifu International Institute of Biotechnology, Kakamigahara, Gifu, Japan.
rck/p54 is a DEAD-box RNA helicase protein with ATP-dependent RNA-unwinding activity. Its ortholog is required for sexual reproduction in yeast and for oocyte survival and sperm fertility in Caenorhabditis elegans. In the current study, we investigated the expression of rck/p54 in mouse gametogenesis and early embryogenesis. Western blot analysis revealed that rck/p54 was highly expressed in both the ovary and testis. In the ovary, maturing oocytes strongly expressed rck/p54 in their cytoplasm. In contrast, in the testis, spermatogonia and primary spermatocytes highly expressed rck/p54 in their cytoplasm, but its expression decreased in the spermatids. Interestingly, rck/p54 was concentrated in the heads of spermatozoa; and then its expression gradually decreased as these cells matured along the epididymal duct. After fertilization, rck/p54 protein and its mRNA remained present in the pronucleus phase; and then their expression levels slightly but definitely decreased in morulae and blastocytes. The injection of a CMV-based rck/p54 expression vector into the pronuclei of fertilized eggs caused a delay in early embryogenesis. In generating RCK transgenic mice, the birth rate of the mice was significantly lower than those of other gene transgenic mice. These findings indicate that rck/p54 may play an important role in gametogenesis and early embryogenesis in mammals. Developmental Dynamics, 2005. (c) 2005 Wiley-Liss, Inc.
Follicle stages
Comment
Dcp1-Bodies in Mouse Oocytes. Swetloff A et al. Monitoring Editor: A. Gregory Matera Processing bodies (P-bodies) are cytoplasmic granules involved in the storage and degradation of mRNAs. In somatic cells, their formation involves miRNA-mediated mRNA silencing. Many P-body protein components are also found in germ cell granules, such as in mammalian spermatocytes. In fully grown mammalian oocytes, where changes in gene expression depend entirely on translational control, RNA granules have not as yet been characterized. Here we show the presence of P-body-like foci in mouse oocytes, as revealed by the presence of Dcp1a and the colocalization of RNA associated protein 55 (RAP55) and the DEAD box RNA helicase Rck/p54, two proteins associated with P-bodies and translational control. These P-body like structures have been called Dcp1-bodies and in meiotically-arrested primary oocytes, two types can be distinguished based upon their size. They also have different protein partners and sensitivities to the depletion of endogenous siRNA/miRNA and translational inhibitors. However, both type progressively disappear during in vitro meiotic maturation, and are virtually absent in metaphase II-arrested secondary oocytes. Moreover, this disassembly of hDcp1a-bodies is concomitant with the post-translational modification of EGFP-hDcp1a.
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: type: null mutation fertility: infertile - ovarian defect Comment: ELAVL2-directed RNA regulatory network drives the formation of quiescent primordial follicles. Kato Y et al. (2019) Formation of primordial follicles is a fundamental, early process in mammalian oogenesis. However, little is known about the underlying mechanisms. We herein report that the RNA-binding proteins ELAVL2 and DDX6 are indispensable for the formation of quiescent primordial follicles in mouse ovaries. We show that Elavl2 knockout females are infertile due to defective primordial follicle formation. ELAVL2 associates with mRNAs encoding components of P-bodies (cytoplasmic RNP granules involved in the decay and storage of RNA) and directs the assembly of P-body-like granules by promoting the translation of DDX6 in oocytes prior to the formation of primordial follicles. Deletion of Ddx6 disturbs the assembly of P-body-like granules and severely impairs the formation of primordial follicles, indicating the potential importance of P-body-like granules in the formation of primordial follicles. Furthermore, Ddx6-deficient oocytes are abnormally enlarged due to misregulated PI3K-AKT signaling. Our data reveal that an ELAVL2-directed post-transcriptional network is essential for the formation of quiescent primordial follicles.//////////////////