title: Effects of C-peptide on isolated human pancreatic islet cells.
abstract: BACKGROUND
  Recent data have demonstrated that pro-insulin-derived C-peptide can affect the function of several different cell types. We hypothesized that C-peptide might have an influence on the function and survival of isolated human islets.
  
  
  METHODS
  Islets were prepared by combining enzymatic digestion and density gradient centrifugation, and the effects of human C-peptide were evaluated acutely and after 24-h incubation. Insulin secretion, apoptosis, quantitative RT-PCR and western-blotting experiments were then performed.
  
  
  RESULTS
  Glucose-stimulated insulin secretion was not affected by C-peptide and, accordingly, mRNA expression of glucose transporter 2 and glucokinase did not differ between islets pre-cultured or not with the hormone. However, apoptosis was significantly lower in islets exposed to C-peptide than in control islets. This was accompanied by a significant increase of mRNA and protein expression of Bcl2, an anti-apoptotic molecule, with no change in the expression of Bax, a pro-apoptotic molecule.
  
  
  CONCLUSIONS
  These results show that in human islets pro-insulin C-peptide has no direct effects on insulin secretion, but it decreases islet cell apoptosis. A direct role of C-peptide on beta-cell mass regulation is therefore suggested.
authors.affiliation: Department of Endocrinology and Metabolism - Metabolic Unit, University of Pisa, Pisa, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bugliani
authors.forename: Scilla
authors.initials: S
authors.lastname: Torri
authors.forename: Roberto
authors.initials: R
authors.lastname: Lupi
authors.forename: Silvia
authors.initials: S
authors.lastname: Del Guerra
authors.forename: Maria
authors.initials: M
authors.lastname: Grupillo
authors.forename: Marco
authors.initials: M
authors.lastname: Del Chiaro
authors.forename: Franco
authors.initials: F
authors.lastname: Mosca
authors.forename: Ugo
authors.initials: U
authors.lastname: Boggi
authors.forename: Stefano
authors.initials: S
authors.lastname: Del Prato
authors.forename: Piero
authors.initials: P
authors.lastname: Marchetti
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002096:C-Peptide / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
chemical_list: D002096:C-Peptide; D007328:Insulin; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein