title: Expression of pro- and antiapoptotic molecules of the Bcl-2 family in human islets postisolation.
abstract: Human islets are subjected to a number of stresses before and during their isolation that may influence their survival and engraftment after transplantation. Apoptosis is likely to be activated in response to these stresses. Apoptosis due to intrinsic stresses is regulated by pro- and  antiapoptotic members of the Bcl-2 family. While the role of the Bcl-2 family in apoptosis of rodent islets is becoming increasingly understood, little is known about which of these molecules are expressed or required for apoptosis of human islets. This study investigated the expression of  the Bcl-2 family of molecules in isolated human islets. RNA and protein lysates were extracted from human islets immediately postisolation. At the same time, standard quality control assays including viability staining and β-cell content were performed on each islet preparation. Microarrays,  RT-PCR, and Western blotting were performed on islet RNA and protein. The prosurvival molecules Bcl-xl and Mcl-1, but not Bcl-2, were highly expressed. The multidomain proapoptotic effector molecule Bax was expressed at higher levels than Bak. Proapoptotic BH3-only molecules were expressed  at low levels, with Bid being the most abundant. The proapoptotic molecules BNIP3, BNIP3L, and Beclin-1 were all highly expressed, indicating exposure of islets to oxygen and nutrient deprivation during isolation. Our data provide a comprehensive analysis of expression levels of pro- and antiapoptotic  Bcl-2 family members in isolated human islets. Knowledge of which molecules are expressed will guide future research to understand the apoptotic pathways activated during isolation or after transplantation. This is crucial for the design of methods to achieve improved transplantation outcomes.
authors.affiliation: St Vincent's Institute, Fitzroy, Australia.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Campbell
authors.forename: Anita
authors.initials: A
authors.lastname: Weinberg
authors.forename: Jonathan
authors.initials: J
authors.lastname: Chee
authors.forename: Lina
authors.initials: L
authors.lastname: Mariana
authors.forename: Rochelle
authors.initials: R
authors.lastname: Ayala
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Hawthorne
authors.forename: Philip J
authors.initials: PJ
authors.lastname: O'Connell
authors.forename: Thomas
authors.initials: T
authors.lastname: Loudovaris
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Cowley
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kay
authors.forename: Shane T
authors.initials: ST
authors.lastname: Grey
authors.forename: Helen E
authors.initials: HE
authors.lastname: Thomas
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D000071186:Beclin-1; D002469:Cell Separation; D006801:Humans; D007515:Islets of Langerhans / Q000378:metabolism*; D016381:Islets of Langerhans Transplantation / Q000379:methods; D008565:Membrane Proteins / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D013312:Stress, Physiological; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C494772:BAK1 protein, human; C494811:BCL2L1 protein, human; C491997:BECN1 protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; C090121:BNIP3 protein, human; C116838:BNIP3L protein, human; D000071186:Beclin-1; D008565:Membrane Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D025521:Tumor Suppressor Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein