The nonmuscle myosin regulatory light chain gene mlc-4 is required for cytokinesis, anterior-posterior polarity, and body morphology during Caenorhabditis elegans embryogenesis.
Using RNA-mediated genetic interference in a phenotypic screen, we identified a conserved nonmuscle myosin II regulatory light chain gene in Caenorhabditis elegans, which we name mlc-4. Maternally supplied mlc-4 function is required for cytokinesis during both meiosis and mitosis and for establishment of anterior-posterior (a-p) asymmetries after fertilization. Reducing the function of mlc-4 or nmy-2, a nonmuscle myosin II gene, also leads to a loss of polarized cytoplasmic flow in the C. elegans zygote, supporting models in which cytoplasmic flow may be required to establish a-p differences. Germline P granule localization at the time of cytoplasmic flow is also lost in these embryos, although P granules do become localized to the posterior pole after the first mitosis. This result suggests that a mechanism other than cytoplasmic flow or mlc-4/nmy-2 activity can generate some a-p asymmetries in the C. elegans zygote. By isolating a deletion allele, we show that removing zygotic mlc-4 function results in an elongation phenotype during embryogenesis. An mlc-4/green fluorescent protein transgene is expressed in lateral rows of hypodermal cells and these cells fail to properly change shape in mlc-4 mutant animals during elongation.
Shelton
C A
CA
Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA.
Carter
J C
JC
Ellis
G C
GC
Bowerman
B
B
D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D016764:Cell Polarity; D048429:Cell Size; D018385:Centrosome / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D047108:Embryonic Development; D017353:Gene Deletion; D017238:Genes, Helminth / Q000235:genetics / Q000502:physiology; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D006720:Homozygote; D009024:Morphogenesis; D009218:Myosins / Q000235:genetics / Q000502:physiology*; D015388:Organelles / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism
D015801:Helminth Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D009218:Myosins