Nematode sperm undergo a drastic physiological change during spermiogenesis(sperm activation).Unlike mammalian flagellated sperm,nematode sperm are amoeboid cells and their motility is driven by the dynamics of a cyto...Nematode sperm undergo a drastic physiological change during spermiogenesis(sperm activation).Unlike mammalian flagellated sperm,nematode sperm are amoeboid cells and their motility is driven by the dynamics of a cytoskeleton composed of major sperm protein(MSP)rather than actin found in other crawling cells.This review focuses on sperm from Caenorhabditis elegans and Ascaris suum to address the roles of external and internal factors that trigger sperm activation and power sperm motility.Nematode sperm can be activated in vitro by several factors,including Pronase and ionophores,and in vivo through the TRY-5 and SPE-8 pathways.Moreover,protease and protease inhibitors are crucial regulators of sperm maturation.MSP-based sperm motility involves a coupled process of protrusion and retraction,both of which have been reconstituted in vitro.Sperm motility is mediated by phosphorylation signals,as illustrated by identification of several key components(MPOP,MFPs and MPAK)in Ascaris and the characterization of GSP-3/4 in C.elegans.展开更多
The dynamic polar polymers actin fi laments and microtu-bules are usually employed to provide the structural ba-sis for establishing cell polarity in most eukaryotic cells.Radially round and immotile spermatids from n...The dynamic polar polymers actin fi laments and microtu-bules are usually employed to provide the structural ba-sis for establishing cell polarity in most eukaryotic cells.Radially round and immotile spermatids from nematodes contain almost no actin or tubulin,but still have the abil-ity to break symmetry to extend a pseudopod and initiate the acquisition of motility powered by the dynamics of cytoskeleton composed of major sperm protein(MSP)during spermiogenesis(sperm activation).However,the signal transduction mechanism of nematode sperm activation and motility acquisition remains poorly under-stood.Here we show that Ca^(2+) oscillations induced by the Ca^(2+) release from intracellular Ca^(2+) store through inositol(1,4,5)-trisphosphate receptor are required for Ascaris suum sperm activation.The chelation of cytosolic Ca^(2+) suppresses the generation of a functional pseudopod,and this suppression can be relieved by introducing ex-ogenous Ca^(2+) into sperm cells.Ca^(2+) promotes MSP-based sperm motility by increasing mitochondrial membrane potential and thus the energy supply required for MSP cytoskeleton assembly.On the other hand,Ca^(2+) promotes MSP disassembly by activating Ca^(2+)/calmodulin-depend-ent serine/threonine protein phosphatase calcineurin.In addition,Ca^(2+)/camodulin activity is required for the fusion of sperm-specifi c membranous organelle with the plasma membrane,a regulated exocytosis required for sperm mo-tility.Thus,Ca^(2+)plays multifunctional roles during sperm activation in Ascaris suum.展开更多
基金supported by the National Basic Research Program of China(Nos.2012CB94502,2010CB912303)(to L.M.)the National Natural Science Foundation of China(Grant Nos.31171337 and 30971648)(to L.M.)+1 种基金Grant Nos.30871226 and 31071180(to Y.Z.)supported by the Chinese Academy of Sciences 100-Talents Program.
文摘Nematode sperm undergo a drastic physiological change during spermiogenesis(sperm activation).Unlike mammalian flagellated sperm,nematode sperm are amoeboid cells and their motility is driven by the dynamics of a cytoskeleton composed of major sperm protein(MSP)rather than actin found in other crawling cells.This review focuses on sperm from Caenorhabditis elegans and Ascaris suum to address the roles of external and internal factors that trigger sperm activation and power sperm motility.Nematode sperm can be activated in vitro by several factors,including Pronase and ionophores,and in vivo through the TRY-5 and SPE-8 pathways.Moreover,protease and protease inhibitors are crucial regulators of sperm maturation.MSP-based sperm motility involves a coupled process of protrusion and retraction,both of which have been reconstituted in vitro.Sperm motility is mediated by phosphorylation signals,as illustrated by identification of several key components(MPOP,MFPs and MPAK)in Ascaris and the characterization of GSP-3/4 in C.elegans.
基金the National Basic Research Program(973 Program)(Nos.2012CB945002 and 2010CB912303)and 31171337 from the Chinese government.
文摘The dynamic polar polymers actin fi laments and microtu-bules are usually employed to provide the structural ba-sis for establishing cell polarity in most eukaryotic cells.Radially round and immotile spermatids from nematodes contain almost no actin or tubulin,but still have the abil-ity to break symmetry to extend a pseudopod and initiate the acquisition of motility powered by the dynamics of cytoskeleton composed of major sperm protein(MSP)during spermiogenesis(sperm activation).However,the signal transduction mechanism of nematode sperm activation and motility acquisition remains poorly under-stood.Here we show that Ca^(2+) oscillations induced by the Ca^(2+) release from intracellular Ca^(2+) store through inositol(1,4,5)-trisphosphate receptor are required for Ascaris suum sperm activation.The chelation of cytosolic Ca^(2+) suppresses the generation of a functional pseudopod,and this suppression can be relieved by introducing ex-ogenous Ca^(2+) into sperm cells.Ca^(2+) promotes MSP-based sperm motility by increasing mitochondrial membrane potential and thus the energy supply required for MSP cytoskeleton assembly.On the other hand,Ca^(2+) promotes MSP disassembly by activating Ca^(2+)/calmodulin-depend-ent serine/threonine protein phosphatase calcineurin.In addition,Ca^(2+)/camodulin activity is required for the fusion of sperm-specifi c membranous organelle with the plasma membrane,a regulated exocytosis required for sperm mo-tility.Thus,Ca^(2+)plays multifunctional roles during sperm activation in Ascaris suum.
