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Autophagy. 2015;11(6):918-27. doi: 10.1080/15548627.2015.1034413.

TipC and the chorea-acanthocytosis protein VPS13A regulate autophagy in Dictyostelium and human HeLa cells.

Author information

1
a Instituto de Investigaciones Biomedicas Alberto Sols; Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid ; Madrid , Spain.

Abstract

Deficient autophagy causes a distinct phenotype in Dictyostelium discoideum, characterized by the formation of multitips at the mound stage. This led us to analyze autophagy in a number of multitipped mutants described previously (tipA(-), tipB(-), tipC(-), and tipD(-)). We found a clear autophagic dysfunction in tipC(-) and tipD(-) while the others showed no defects. tipD codes for a homolog of Atg16, which confirms the role of this protein in Dictyostelium autophagy and validates our approach. The tipC-encoded protein is highly similar to human VPS13A (also known as chorein), whose mutations cause the chorea-acanthocytosis syndrome. No member of the VPS13 protein family has been previously related to autophagy despite the presence of a region of similarity to Atg2 at the C terminus. This region also contains the conserved domain of unknown function DUF1162. Of interest, the expression of the TipC C-terminal coding sequence containing these 2 motifs largely complemented the mutant phenotype. Dictyostelium cells lacking TipC displayed a reduced number of autophagosomes visualized with the markers GFP-Atg18 and GFP-Atg8 and an impaired autophagic degradation as determined by a proteolytic cleavage assay. Downregulation of human VPS13A in HeLa cells by RNA interference confirmed the participation of the human protein in autophagy. VPS13A-depleted cells showed accumulation of autophagic markers and impaired autophagic flux.

KEYWORDS:

ATG, autophagy related; AX4, axenic strain 4; DUF, domain of unknown function; Dictyostelium; GFP, green fluorescent protein; HeLa cells; LC3, microtubule-associated protein 1 light chain 3; PtdIns3K, phosphatidylinositol 3-kinase; PtdIns3P, phosphatidylinositol 3-phosphate; TipC; VPS13; VPS13, vacuolar protein sorting 13 homolog (S. cerevisiae); VPS13A; WIPI, WD repeat domain, phosphoinoside interacting; autophagy; chorea-acanthocytosis; chorein

PMID:
25996471
PMCID:
PMC4507429
DOI:
10.1080/15548627.2015.1034413
[Indexed for MEDLINE]
Free PMC Article

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