RNA Granules in Germ Cells. + Author Affiliations Correspondence: evoronina@jhmi.edu (E.V.); gseydoux@jhmi.edu (G.S.); psc@uci.edu (P.S.
-C.); inagamor@uci.edu (I.N.) “Germ granules” are cytoplasmic, nonmembrane-bound organelles unique to germline. Germ granules share components with the P bodies and stress granules of somatic cells, but also contain proteins and RNAs uniquely required for germ cell development. In this review, we focus on recent advances in our understanding of germ granule assembly, dynamics, and function. Mammalian Genomic Imprinting. Small Noncoding RNAs in the Germline. Small noncoding RNAs have emerged as potent regulators of gene expression, especially in the germline.
We review the biogenesis and regulatory function of three major small noncoding RNA pathways in the germline: The small interfering RNA (siRNA) pathway that leads to the degradation of target mRNAs, the microRNA (miRNA) pathway that mostly represses the translation of target mRNAs, and the newly discovered Piwi-interacting RNA (piRNA) pathway that appears to have diverse functions in epigenetic programming, transposon silencing, and the regulation of mRNA translation and stability. The siRNA and miRNA pathways are present in the germline as well as many somatic tissues, whereas the piRNA pathway is predominantly confined to the germline.
Investigation of the three small RNA pathways has started to reveal a new dimension of gene regulation with defining roles in germline specification and development. Copyright © 2011 Cold Spring Harbor Laboratory Press; all rights reserved.