C. elegans HAM-1 positions the cleavage plane and regulates apoptosis in asymmetric neuroblast divisions.
Asymmetric cell division occurs when a mother cell divides to generate two distinct daughter cells, a process that promotes the generation of cellular diversity in metazoans. During Caenorhabditis elegans development, the asymmetric divisions of neural progenitors generate neurons, neural support cells and apoptotic cells. C. elegans HAM-1 is an asymmetrically distributed cortical protein that regulates several of these asymmetric neuroblast divisions. Here, we show that HAM-1 is a novel protein and define residues important for HAM-1 function and distribution to the cell cortex. Our phenotypic analysis of ham-1 mutant embryos suggests that HAM-1 controls only neuroblast divisions that produce apoptotic cells. Moreover, ham-1 mutant embryos contain many unusually large cell-death corpses. An investigation of this corpse phenotype revealed that it results from a reversal of neuroblast polarity. A misplacement of the neuroblast cleavage plane generates daughter cells of abnormal size, with the apoptotic daughters larger than normal. Thus, HAM-1 regulates the position of the cleavage plane, apoptosis and mitotic potential in C. elegans asymmetric cell divisions.
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3204, USA.
C Andrew
CA
Frank
Nancy C
NC
Hawkins
Catherine
C
Guenther
H Robert
HR
Horvitz
Gian
G
Garriga
D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D017209:Apoptosis; D001120:Arginine / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002455:Cell Division; D048429:Cell Size; D016384:Consensus Sequence; D017124:Conserved Sequence; D049452:Green Fluorescent Proteins / Q000378:metabolism; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007150:Immunohistochemistry; D008954:Models, Biological; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D019076:Transgenes
D029742:Caenorhabditis elegans Proteins; C103072:HAM-1 protein, C elegans; D015801:Helminth Proteins; D009419:Nerve Tissue Proteins; D049452:Green Fluorescent Proteins; D001224:Aspartic Acid; D001120:Arginine