title: The DEP domain-containing protein TOE-2 promotes apoptosis in the Q lineage of C. elegans through two distinct mechanisms.
abstract: Neuroblast divisions in the nematode Caenorhabditis elegans often give rise to a larger neuron and a smaller cell that dies. We have previously identified genes that, when mutated, result in neuroblast divisions that generate daughter cells that are more equivalent in size. This effect correlates with the survival of daughter cells that would normally die. We now describe a role for the DEP domain-containing protein TOE-2 in promoting the apoptotic fate in the Q lineage. TOE-2 localized at the plasma membrane and accumulated in the cleavage furrow of the Q.a and Q.p neuroblasts, suggesting that TOE-2 might position the cleavage furrow asymmetrically to generate daughter cells of different sizes. This appears to be the case for Q.a divisions where loss of TOE-2 led to a more symmetric division and to survival of the smaller Q.a daughter. Localization of TOE-2 to the membrane is required for this asymmetry, but, surprisingly, the DEP domain is dispensable. By contrast, loss of TOE-2 led to loss of the apoptotic fate in the smaller Q.p daughter but did not affect the size asymmetry of the Q.p daughters. This function of TOE-2 required the DEP domain but not localization to the membrane. We propose that TOE-2 ensures an apoptotic fate for the small Q.a daughter by promoting asymmetry in the daughter cell sizes of the Q.a neuroblast division but by a mechanism that is independent of cell size in the Q.p division.
authors: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
authors: Mark
authors: M
authors: Gurling
authors: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
authors: Karla
authors: K
authors: Talavera
authors: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA garriga@berkeley.edu.
authors: Gian
authors: G
authors: Garriga
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D019070:Cell Lineage / Q000235:genetics / Q000502:physiology*; D002874:Chromosome Mapping; D017931:DNA Primers / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D034622:RNA Interference; D017422:Sequence Analysis, DNA; D018709:Statistics, Nonparametric; D059008:Time-Lapse Imaging
chemical_list: D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; C000590872:TOE-2 protein, C elegans
keywords: Apoptosis; Asymmetric cell division; Cell fate; Neuroblast; Programmed cell death; TOE-2