MSP and GLP-1/Notch signaling coordinately regulate actomyosin-dependent cytoplasmic streaming and oocyte growth in C. elegans

Saravanapriah Nadarajan, J. Amaranath Govindan, Marie McGovern, E. Jane Albert Hubbard, David Greenstein

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

Fertility depends on germline stem cell proliferation, meiosis and gametogenesis, yet how these key transitions are coordinated is unclear. In C. elegans, we show that GLP-1/Notch signaling functions in the germline to modulate oocyte growth when sperm are available for fertilization and the major sperm protein (MSP) hormone is present. Reduction-of-function mutations in glp-1 cause oocytes to grow abnormally large when MSP is present and Gαs-adenylate cyclase signaling in the gonadal sheath cells is active. By contrast, gain-of-function glp-1 mutations lead to the production of small oocytes. Surprisingly, proper oocyte growth depends on distal tip cell signaling involving the redundant function of GLP-1 ligands LAG-2 and APX-1. GLP-1 signaling also affects two cellular oocyte growth processes, actomyosin-dependent cytoplasmic streaming and oocyte cellularization. glp-1 reduction-of-function mutants exhibit elevated rates of cytoplasmic streaming and delayed cellularization. GLP-1 signaling in oocyte growth depends in part on the downstream function of the FBF-1/2 PUF RNA-binding proteins. Furthermore, abnormal oocyte growth in glp-1 mutants, but not the inappropriate differentiation of germline stem cells, requires the function of the cell death pathway. The data support a model in which GLP-1 function in MSP-dependent oocyte growth is separable from its role in the proliferation versus meiotic entry decision. Thus, two major germline signaling centers, distal GLP-1 activation and proximal MSP signaling, coordinate several spatially and temporally distinct processes by which germline stem cells differentiate into functional oocytes.

Original languageEnglish (US)
Pages (from-to)2223-2234
Number of pages12
JournalDevelopment
Volume136
Issue number13
DOIs
StatePublished - Jul 1 2009

Keywords

  • Caenorhabditis elegans
  • Cytoplasmic streaming
  • Germline stem cell
  • MSP signaling
  • Meiosis
  • Meiotic maturation
  • Notch signaling

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