title: Perilipin discerns chronic from acute hepatocellular steatosis.
abstract: OBJECTIVE
  Hepatocellular steatosis is the most frequent liver disease in the western world and may develop further to steatohepatitis, liver cirrhosis and hepatocellular carcinoma. We have previously shown that lipid droplet (LD)-associated proteins of the perilipin/PAT-family are differentially expressed in hepatocyte steatosis and that perilipin is expressed de novo. The aim of this study was to determine the conditions for the temporal regulation of de novo synthesis of perilipin in vitro and in vivo.
  
  
  METHODS
  Immunohistochemical PAT-analysis was performed with over 120 liver biopsies of different etiology and duration of steatosis. Steatosis was induced in cultured hepatocytic cells with combinations of lipids, steatogenic substances and DMSO for up to 40 days under conditions of stable down-regulation of adipophilin and/or TIP47.
  
  
  RESULTS
  Whereas perilipin and adipophilin were expressed in human chronic liver disease irrespective of the underlying etiology, in acute/microvesicular steatosis TIP47, and MLDP were recruited from the cytoplasm to LDs, adipophilin was strongly increased, but perilipin was virtually absent. In long-term steatosis models in vitro, TIP47, MLDP, adipophilin, and finally perilipin were gradually induced. Perilipin and associated formation of LDs were intricately regulated on the transcriptional (PPARs, C/EBPs, SREBP), post-transcriptional, and post-translational level (TAG-amount, LD-fusion, phosphorylation-dependent lipolysis). In long-term steatosis models under stable down-regulation of adipophilin and/or TIP47, MLDP substituted for TIP47, and perilipin for adipophilin.
  
  
  CONCLUSIONS
  LD-maturation in hepatocytes in vivo and in vitro involves sequential expression of TIP47, MLDP, adipophilin and finally perilipin. Thus, perilipin might be used for the differential diagnosis of chronic vs. acute steatosis.
authors.affiliation: Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany.
authors.forename: Lena Maria
authors.initials: LM
authors.lastname: Pawella
authors.affiliation: Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany.
authors.forename: Merita
authors.initials: M
authors.lastname: Hashani
authors.affiliation: Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Eiteneuer
authors.affiliation: Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Renner
authors.affiliation: Department for Infectious Diseases, Molecular Virology, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Bartenschlager
authors.affiliation: Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schirmacher
authors.affiliation: Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany. Electronic address: beate.straub@med.uni-heidelberg.de.
authors.forename: Beate Katharina
authors.initials: BK
authors.lastname: Straub
mesh_terms: D000208:Acute Disease; D002352:Carrier Proteins / Q000032:analysis / Q000502:physiology*; D002478:Cells, Cultured; D002908:Chronic Disease; D005234:Fatty Liver / Q000378:metabolism*; D006801:Humans; D008066:Lipolysis; D016031:Liver Transplantation; D008565:Membrane Proteins / Q000502:physiology; D047493:PPAR alpha / Q000502:physiology; D047495:PPAR gamma / Q000502:physiology; D000070778:Perilipin-1; D000070780:Perilipin-2; D000070796:Perilipin-3; D010750:Phosphoproteins / Q000032:analysis / Q000502:physiology*; D033921:Vesicular Transport Proteins / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; C000602982:PLIN2 protein, human; C038196:PLIN3 protein, human; D047493:PPAR alpha; D047495:PPAR gamma; D000070778:Perilipin-1; D000070780:Perilipin-2; D000070796:Perilipin-3; D010750:Phosphoproteins; D033921:Vesicular Transport Proteins
keywords: ADRP; AFLD; ASH; Adipophilin; C/EBP; CCAAT/enhancer-binding protein; CE; DMSO; HFD; HSL; IRI; LD; LTX; Lipid droplet; MLDP; NAFLD; NASH; PAT; PAT-protein family; PPAR; RT; Steatohepatitis; TAG; TIP47; adipose differentiation-related protein; alcoholic fatty liver disease; alcoholic steatohepatitis; cholesterol-ester; dimethylsulfoxide; high fat diet; hormone-sensitive lipase; ischemia-reperfusion injury; lipid droplet; liver transplantation; myocardial lipid droplet protein; non-alcoholic fatty liver disease; non-alcoholic steatohepatitis; perilipin/adipophilin/TIP47-protein-family; peroxisome proliferator activating-receptor; room temperature; tail-interacting protein 47kDa; triacylglyceride