title: Characterization of the sebocyte lipid droplet proteome reveals novel potential regulators of sebaceous lipogenesis.
abstract: Lipid metabolism depends on lipid droplets (LD), cytoplasmic structures surrounded by a protein-rich phospholipid monolayer. Although lipid synthesis is the hallmark of sebaceous gland cell differentiation, the LD-associated proteins of sebocytes have not been evaluated systematically. The LD fraction of SZ95 sebocytes was collected by density gradient centrifugation and associated proteins were analyzed by nanoliquid chromatography/tandem mass spectrometry. 54 proteins were significantly enriched in LD fractions, and 6 of them have not been detected previously in LDs. LD fractions contained high levels of typical LD-associated proteins as PLIN2/PLIN3, and most proteins belonged to functional categories characteristic for LD-associated proteins, indicating a reliable dataset. After confirming expression of transcripts encoding the six previously unidentified proteins by qRT-PCR in SZ95 sebocytes and in another sebocyte line (SebE6E7), we focused on two of these proteins, ALDH1A3 and EPHX4. While EPHX4 was localized almost exclusively on the surface of LDs, ALDH1A3 showed a more widespread localization that included additional cytoplasmic structures. siRNA-mediated downregulation revealed that depletion of EPHX4 increases LD size and sebaceous lipogenesis. Further studies on the roles of these proteins in sebocyte physiology and sebaceous lipogenesis may indicate novel strategies for the therapy of sebaceous gland-associated diseases such as acne.
authors.affiliation: Institute of Molecular Animal Breeding and Biotechnology, Gene Center, LMU Munich, Germany.
authors.forename: Maik
authors.initials: M
authors.lastname: Dahlhoff
authors.affiliation: Laboratory for Functional Genome Analysis LAFUGA, Gene Center, LMU Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fröhlich
authors.affiliation: Laboratory for Functional Genome Analysis LAFUGA, Gene Center, LMU Munich, Germany.
authors.forename: Georg J
authors.initials: GJ
authors.lastname: Arnold
authors.affiliation: Human Biology and BioImaging, Department of Biology II, LMU Munich, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Müller
authors.affiliation: Human Biology and BioImaging, Department of Biology II, LMU Munich, Germany.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Leonhardt
authors.affiliation: Departments of Dermatology, Venereology, Allergology and Immunology, Dessau Medical Center, Dessau, Germany.
authors.forename: Christos C
authors.initials: CC
authors.lastname: Zouboulis
authors.affiliation: Institute of Molecular Animal Breeding and Biotechnology, Gene Center, LMU Munich, Germany. Electronic address: marlon.schneider@lmu.de.
authors.forename: Marlon R
authors.initials: MR
authors.lastname: Schneider
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D002460:Cell Line; D004851:Epoxide Hydrolases / Q000378:metabolism; D006801:Humans; D066292:Lipid Droplets / Q000378:metabolism*; D050155:Lipogenesis; D020543:Proteome / Q000378:metabolism*; D012627:Sebaceous Glands / Q000166:cytology / Q000378:metabolism*
chemical_list: D020543:Proteome; D000445:Aldehyde Oxidoreductases; C018699:aldehyde dehydrogenase (NAD(P)+); C577761:EPHX4 protein, human; D004851:Epoxide Hydrolases
keywords: Acne; Lipid droplets; Proteomics; Sebaceous glands