title: C. elegans NIMA-related kinases NEKL-2 and NEKL-3 are required for the completion of molting.
abstract: Caenorhabditis elegans molting is a process during which the apical extracellular matrix of the epidermis, the cuticle, is remodeled through a process of degradation and re-synthesis. Using a genetic approach, we identified nekl-3 as essential for the completion of molting. NEKL-3 is highly similar to the mammalian NEK kinase family members NEK6 and NEK7. Animals homozygous for a hypomorphic mutation in nekl-3, sv3, had a novel molting defect in which the central body region, but not the head or tail, was unable to shed the old cuticle. In contrast, a null mutation in nekl-3, gk506, led to complete enclosure within the old cuticle. nekl-2, which is most similar to mammalian NEK8, was also essential for molting. Mosaic analyses demonstrated that NEKL-2 and NEKL-3 were specifically required within the large epidermal syncytium, hyp7, to facilitate molting. Consistent with this, NEKL-2 and NEKL-3 were expressed at the apical surface of hyp7 where they localized to small spheres or tubular structures. Inhibition of nekl-2, but not nekl-3, led to the mislocalization of LRP-1/megalin, a cell surface receptor for low-density lipoprotein (LDL)-binding proteins. In addition, nekl-2 inhibition led to the mislocalization of several other endosome-associated proteins. Notably, LRP-1 acts within hyp7 to facilitate completion of molting, suggesting at least one mechanism by which NEKL-2 may influence molting. Notably, our studies failed to reveal a requirement for NEKL-2 or NEKL-3 in cell division, a function reported for several mammalian NEKs including NEK6 and NEK7. Our findings provide the first genetic and in vivo evidence for a role of NEK family members in endocytosis, which may be evolutionarily conserved.
authors.affiliation: Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY 82071, United States; Department of Genetics, Cell Biology, and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, United States.
authors.forename: John
authors.initials: J
authors.lastname: Yochem
authors.affiliation: Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY 82071, United States.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Lažetić
authors.affiliation: Department of Genetics, Cell Biology, and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, United States.
authors.forename: Leslie
authors.initials: L
authors.lastname: Bell
authors.affiliation: Department of Genetics, Cell Biology, and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, United States.
authors.forename: Lihsia
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY 82071, United States. Electronic address: davidfay@uwyo.edu.
authors.forename: David
authors.initials: D
authors.lastname: Fay
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D005453:Fluorescence; D017238:Genes, Helminth; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018978:Molting; D009030:Mosaicism; D009154:Mutation / Q000235:genetics; D000072379:NIMA-Related Kinases; D010641:Phenotype; D010802:Phylogeny; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D040521:Subcutaneous Tissue / Q000196:embryology / Q000378:metabolism
chemical_list: D015415:Biomarkers; D029742:Caenorhabditis elegans Proteins; C000596672:NEKL-3 protein, C elegans; D049452:Green Fluorescent Proteins; D011494:Protein Kinases; C000596671:NEKL-2 protein, C elegans; D000072379:NIMA-Related Kinases
keywords: C. elegans; Endocytosis; Kinases; Molting; NEK; NEKL-2; NEKL-3; hyp7