title: Hyperglycemia-induced downregulation of apolipoprotein M expression is not via the hexosamine pathway.
abstract: BACKGROUND
  We previously demonstrated that hyperglycemia could suppress apolipoprotein M (apoM) synthesis both in vivo and in vitro; however, the mechanism of hyperglycemia-induced downregulation of apoM expression is unknown yet.
  
  
  METHODS
  In the present study we further examined if hexosamine pathway, one of the most important pathways of glucose turnover, being involved in modulating apoM expression in the hyperglycemia condition. We examined the effect of glucosamine, a prominent component of hexosamine pathway and intracellular mediator of insulin resistance, on apoM expression in HepG2 cells and in rat's models. In the present study we also determined apolipoprotein A1 (apoA1) as a control gene.
  
  
  RESULTS
  Our results demonstrated that glucosamine could even up-regulate both apoM and apoA1 expressions in HepG2 cell cultures. The glucosamine induced upregulation of apoM expression could be blocked by addition of azaserine, an inhibitor of hexosamine pathway. Moreover, intravenous infusion of glucosamine could enhance hepatic apoM expression in rats, although serum apoM levels were not significantly influences.
  
  
  CONCLUSIONS
  It is concluded that both exogenous and endogenous glucosamine were essential for the over-expression of apoM, which may suggest that the increased intracellular content of glucosamine does not be responsible for the depressed apoM expression at hyperglycemia condition.
authors.affiliation: Department of Cardiothoracic Surgery in the Third Affiliated Hospital, Soochow University, Changzhou, 213003, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Department of Cardiothoracic Surgery in the Third Affiliated Hospital, Soochow University, Changzhou, 213003, China. xiaoyingzhang6689996@msn.com.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Cardiothoracic Surgery in the Third Affiliated Hospital, Soochow University, Changzhou, 213003, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Di
authors.affiliation: Comprehensive Laboratory, Third Affiliated Hospital, Soochow University, Changzhou, 213003, China.
authors.forename: Guanghua
authors.initials: G
authors.lastname: Luo
authors.affiliation: Comprehensive Laboratory, Third Affiliated Hospital, Soochow University, Changzhou, 213003, China.
authors.forename: Yuanping
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Comprehensive Laboratory, Third Affiliated Hospital, Soochow University, Changzhou, 213003, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lund University, S-221 85, Lund, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Berggren-Söderlund
authors.affiliation: Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lund University, S-221 85, Lund, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Nilsson-Ehle
authors.affiliation: Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lund University, S-221 85, Lund, Sweden. ning.xu@med.lu.se.
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D016632:Apolipoprotein A-I / Q000235:genetics* / Q000378:metabolism; D001053:Apolipoproteins / Q000235:genetics* / Q000378:metabolism; D000075243:Apolipoproteins M; D001377:Azaserine / Q000494:pharmacology; D005786:Gene Expression Regulation; D005944:Glucosamine / Q000008:administration & dosage / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D006943:Hyperglycemia / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D007262:Infusions, Intravenous; D054834:Lipocalins / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction
chemical_list: C400523:APOM protein, human; D000964:Antimetabolites, Antineoplastic; D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D000075243:Apolipoproteins M; C521701:Apom protein, rat; D054834:Lipocalins; D001377:Azaserine; D005944:Glucosamine