title: Major sperm protein signaling promotes oocyte microtubule reorganization prior to fertilization in Caenorhabditis elegans.
abstract: In most animals, female meiotic spindles assemble in the absence of centrosomes; instead, microtubule nucleation by chromatin, motor activity, and microtubule dynamics drive the self-organization of a bipolar meiotic spindle. Meiotic spindle assembly commences when microtubules gain access to chromatin after nuclear envelope breakdown (NEBD) during meiotic maturation. Although many studies have addressed the chromatin-based mechanism of female meiotic spindle assembly, it is less clear how signaling influences microtubule localization and dynamics prior to NEBD. Here we analyze microtubule behavior in Caenorhabditis elegans oocytes at early stages of the meiotic maturation process using confocal microscopy and live-cell imaging. In C. elegans, sperm trigger oocyte meiotic maturation and ovulation using the major sperm protein (MSP) as an extracellular signaling molecule. We show that MSP signaling reorganizes oocyte microtubules prior to NEBD and fertilization by affecting their localization and dynamics. We present evidence that MSP signaling reorganizes oocyte microtubules through a signaling network involving antagonistic G alpha(o/i) and G alpha(s) pathways and gap-junctional communication with somatic cells of the gonad. We propose that MSP-dependent microtubule reorganization promotes meiotic spindle assembly by facilitating the search and capture of microtubules by meiotic chromatin following NEBD.
authors.affiliation: Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Jana E
authors.initials: JE
authors.lastname: Harris
authors.forename: J Amaranath
authors.initials: JA
authors.lastname: Govindan
authors.forename: Ikuko
authors.initials: I
authors.lastname: Yamamoto
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Irina
authors.initials: I
authors.lastname: Kaverina
authors.forename: David
authors.initials: D
authors.lastname: Greenstein
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D016764:Cell Polarity; D012734:Disorders of Sex Development; D004789:Enzyme Activation; D005306:Fertilization / Q000502:physiology*; D036681:Fluorescence Recovery After Photobleaching; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D015801:Helminth Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D013084:Sperm-Ovum Interactions / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D015801:Helminth Proteins; C050602:major sperm protein, nematode; D020794:Receptor Protein-Tyrosine Kinases; C111040:vab-1 protein, C elegans; D020928:Mitogen-Activated Protein Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs