DAPK interacts with Patronin and the microtubule cytoskeleton in epidermal development and wound repair

Abstract

Epidermal barrier epithelia form a first line of defense against the environment, protecting animals against infection and repairing physical damage. In C. elegans, death-associated protein kinase (DAPK-1) regulates epidermal morphogenesis, innate immunity and wound repair. Combining genetic suppressor screens and pharmacological tests, we find that DAPK-1 maintains epidermal tissue integrity through regulation of the microtubule (MT) cytoskeleton. dapk-1 epidermal phenotypes are suppressed by treatment with microtubule-destabilizing drugs and mimicked or enhanced by microtubule-stabilizing drugs. Loss of function in ptrn-1, the C. elegans member of the Patronin/Nezha/CAMSAP family of MT minus-end binding proteins, suppresses dapk-1 epidermal and innate immunity phenotypes. Over-expression of the MT-binding CKK domain of PTRN-1 triggers epidermal and immunity defects resembling those of dapk-1 mutants, and PTRN-1 localization is regulated by DAPK-1. DAPK-1 and PTRN-1 physically interact in co-immunoprecipitation experiments, and DAPK-1 itself undergoes MT-dependent transport. Our results uncover an unexpected interdependence of DAPK-1 and the microtubule cytoskeleton in maintenance of epidermal integrity.DOI: http://dx.doi.org/10.7554/eLife.15833.001

PTRN‐1/CAMSAPpromotesCYK‐1/formin‐dependent actin polymerization during endocytic recycling

“…We first tested the distribution of PTRN‐1‐GFP in rab‐5(RNAi) animals and found no significant change in PTRN‐1‐GFP localization (Fig EV5A and A′), which suggests that RAB‐5 is not implicated in the recruitment or positioning of PTRN‐1‐GFP. Second, a recent study by Chuang et al () documented that PTRN‐1 intracellular localization is regulated by DAPK‐1 in C. elegans epidermis. Surprisingly, we failed to observe the abnormality in the distribution of PTRN‐1‐GFP in dapk‐1(RNAi) animals, suggestive that DAPK‐1 functionality is tissue‐specific and does not appear to supervise the intracellular positioning of PTRN‐1 in the intestinal cells (Fig EV5A and A′).…”

“…The CKK domain is located along epidermal microtubules, and the ectopic expression of the CKK domain perturbed the epidermal morphology. The presence of the PTRN‐1 CC domain acts to restrain the CKK domain activity (Chuang et al , ). Given these findings, the characterization of the PTRN‐1 domains provided insight into the mechanism by which PTRN‐1 functions in the regulation of the cytoskeleton.…”

Tissue-specific regulation of alternative polyadenylation represses expression of a neuronal ankyrin isoform in C. elegans epidermal development

“…DAPK-1 is not localized to cell nuclei (Chuang et al, 2016) nor does loss of function in dapk-1 affect expression levels of SYDN-1, suggesting DAPK-1 might regulate the SYDN-1/SSUP-72 pathway indirectly.…”

“…Loss of DAPK-1 function, as caused by the dominantnegative ju4 allele or by the gk219 deletion allele, results in morphological defects in the epidermis (Mor phenotype) and formation of progressive scar-like structures in the cuticle (Chuang et al, 2016). These defects are suppressed by sydn-1(0) (Tong et al, 2009), and this suppression is rescued by epidermal expression of SYDN-1, indicating SYDN-1 functions cell-autonomously in the UNC-44L (unc-44( ju1412[unc-44L::gfp])) in the genotypes indicated.…”

“…We tested two alleles of dapk-1: ju4 and gk219 (Chuang et al, 2016). dapk-1( ju4) mutants displayed increased UNC-44L::GFP expression in L4 seam cells, and ectopic expression of UNC-44L::GFP in the head and tail epidermal cells at L4 and later stages (Fig.…”