Proteomic profiling of hepatic endoplasmic reticulum-associated proteins in an animal model of insulin resistance and metabolic dyslipidemia.
Hepatic insulin resistance and lipoprotein overproduction are common features of the metabolic syndrome and insulin-resistant states. A fructose-fed, insulin-resistant hamster model was recently developed to investigate mechanisms linking the development of hepatic insulin resistance and overproduction of atherogenic lipoproteins. Here we report a systematic analysis of protein expression profiles in the endoplasmic reticulum (ER) fractions isolated from livers of fructose-fed hamsters with the intention of identifying new candidate proteins involved in hepatic complications of insulin resistance and lipoprotein dysregulation. We have profiled hepatic ER-associated proteins from chow-fed (control) and fructose-fed (insulin-resistant) hamsters using two-dimensional gel electrophoresis and mass spectrometry. A total of 26 large scale two-dimensional gels of hepatic ER were used to identify 34 differentially expressed hepatic ER protein spots observed to be at least 2-fold differentially expressed with fructose feeding and the onset of insulin resistance. Differentially expressed proteins were identified by matrix-assisted laser desorption ionization-quadrupole time of flight (MALDI-Q-TOF), MALDI-TOF-postsource decay, and database mining using ProteinProspector MS-fit and MS-tag or the PROWL ProFound search engine using a focused rodent or mammalian search. Hepatic ER proteins ER60, ERp46, ERp29, glutamate dehydrogenase, and TAP1 were shown to be more than 2-fold down-regulated, whereas alpha-glucosidase, P-glycoprotein, fibrinogen, protein disulfide isomerase, GRP94, and apolipoprotein E were all found to be up-regulated in the hepatic ER of the fructose-fed hamster. Seven isoforms of ER60 in the hepatic ER were all shown to be down-regulated at least 2-fold in hepatocytes from fructosefed/insulin-resistant hamsters. Implications of the differential expression of positively identified protein factors in the development of hepatic insulin resistance and lipoprotein abnormalities are discussed.
Morand
Jean-Paul F
JP
Division of Clinical Biochemistry, and Structural Biology and Biochemistry, Department of Pediatric Laboratory Medicine, Research Institute, The Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada.
Macri
Joseph
J
Adeli
Khosrow
K
D000595:Amino Acid Sequence; D000818:Animals; D006224:Cricetinae; D004195:Disease Models, Animal; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling / Q000379:methods*; D006360:Heat-Shock Proteins / Q000032:analysis / Q000235:genetics*; D006949:Hyperlipidemias / Q000235:genetics*; D007333:Insulin Resistance / Q000235:genetics*; D008099:Liver / Q000737:chemistry; D008297:Male; D008647:Mesocricetus; D008969:Molecular Sequence Data; D040901:Proteomics / Q000379:methods*; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism
D006360:Heat-Shock Proteins