Yusuke Ohno1, Atsuki Nara2, Shota Nakamichi1, Akio Kihara3. 1. Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan. 2. Faculty of Bioscience, Nagahama Institute of Bio-science and Technology, Nagahama 526-0829, Japan. 3. Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan. Electronic address: kihara@pharm.hokudai.ac.jp.
Abstract
BACKGROUND: ABHD5 mutations cause Chanarin-Dorfman syndrome accompanied by ichthyosis. ω-O-Acylceramide (acylceramide) is essential for skin permeability barrier formation. Acylceramide production is impaired in Abhd5 knockout mice. The transacylase PNPLA1 catalyzes the final step of acylceramide production: transfer of linoleic acid in triglyceride to ω-hydroxyceramide. OBJECTIVE: We aimed to elucidate the role of ABHD5 in acylceramide production and the molecular mechanism of the ichthyosis symptoms of Chanarin-Dorfman syndrome. METHODS: We investigated how ABHD5 influences acylceramide production using an acylceramide-producing cell system. The effects of ABHD5 and PNPLA1 expression on the morphology of lipid droplets were examined by indirect immunofluorescent microscopy and immunoelectron microscopy. RESULTS: When ABHD5 was expressed in the acylceramide-producing cell system, acylceramide synthesis by PNPLA1 was enhanced. Dispersed localization of PNPLA1 was observed by immunofluorescent microscopy in HeLa cells under lipid droplet-forming conditions. Co-expression with ABHD5 caused PNPLA1 to localize on the lipid droplet membranes or their periphery. This staining pattern was observed in cells where PNPLA1 and ABHD5 were expressed at low levels. In contrast, lipid droplets disappeared in cells where PNPLA1 and ABHD5 were highly expressed. Immunoelectron microscopic analyses suggested that lipid droplets underwent morphological changes, transforming into vesicles or becoming incorporated into the endoplasmic reticulum. ABHD5 mutations found in Chanarin-Dorfman syndrome patients reduced ABHD5's ability to promote PNPLA1-dependent acylceramide production. CONCLUSION: ABHD5 enhances PNPLA1-catalyzed acylceramide production. We speculate that ABHD5 retains triglycerides in the endoplasmic reticulum, and presents them to PNPLA1 to promote substrate recognition.
BACKGROUND:ABHD5 mutations cause Chanarin-Dorfman syndrome accompanied by ichthyosis. ω-O-Acylceramide (acylceramide) is essential for skin permeability barrier formation. Acylceramide production is impaired in Abhd5 knockout mice. The transacylase PNPLA1 catalyzes the final step of acylceramide production: transfer of linoleic acid in triglyceride to ω-hydroxyceramide. OBJECTIVE: We aimed to elucidate the role of ABHD5 in acylceramide production and the molecular mechanism of the ichthyosis symptoms of Chanarin-Dorfman syndrome. METHODS: We investigated how ABHD5 influences acylceramide production using an acylceramide-producing cell system. The effects of ABHD5 and PNPLA1 expression on the morphology of lipid droplets were examined by indirect immunofluorescent microscopy and immunoelectron microscopy. RESULTS: When ABHD5 was expressed in the acylceramide-producing cell system, acylceramide synthesis by PNPLA1 was enhanced. Dispersed localization of PNPLA1 was observed by immunofluorescent microscopy in HeLa cells under lipid droplet-forming conditions. Co-expression with ABHD5 caused PNPLA1 to localize on the lipid droplet membranes or their periphery. This staining pattern was observed in cells where PNPLA1 and ABHD5 were expressed at low levels. In contrast, lipid droplets disappeared in cells where PNPLA1 and ABHD5 were highly expressed. Immunoelectron microscopic analyses suggested that lipid droplets underwent morphological changes, transforming into vesicles or becoming incorporated into the endoplasmic reticulum. ABHD5 mutations found in Chanarin-Dorfman syndrome patients reduced ABHD5's ability to promote PNPLA1-dependent acylceramide production. CONCLUSION:ABHD5 enhances PNPLA1-catalyzed acylceramide production. We speculate that ABHD5 retains triglycerides in the endoplasmic reticulum, and presents them to PNPLA1 to promote substrate recognition.
Authors: Kristyna Brejchova; Franz Peter Walter Radner; Laurence Balas; Veronika Paluchova; Tomas Cajka; Hana Chodounska; Eva Kudova; Margarita Schratter; Renate Schreiber; Thierry Durand; Rudolf Zechner; Ondrej Kuda Journal: Proc Natl Acad Sci U S A Date: 2021-01-12 Impact factor: 11.205
Authors: Jason M Meyer; Debra Crumrine; Holm Schneider; Angela Dick; Matthias Schmuth; Robert Gruber; Franz P W Radner; Susanne Grond; Joan S Wakefield; Theodora M Mauro; Peter M Elias Journal: Am J Pathol Date: 2021-02-17 Impact factor: 4.307