TY - JOUR
T1 - Proapoptotic bax is hyperexpressed in isolated human islets compared with antiapoptotic BCL-2
AU - Thomas, Dolca
AU - Yang, Hua
AU - Boffa, Daniel J.
AU - Ding, Ruchuang
AU - Sharma, Vijay K.
AU - Lagman, Milagros
AU - Li, Baogui
AU - Hering, Bernhard
AU - Mohanakumar, Thalachallour
AU - Lakey, Jonathan
AU - Kapur, Sandip
AU - Hancock, Wayne W.
AU - Suthanthiran, Manikkam
PY - 2002/12/15
Y1 - 2002/12/15
N2 - Background. Apoptosis is a well-documented pathway for islet cell death. One potential mechanism is overexpression of death-promoting Bax compared with antiapoptotic Bcl-2 in islets. Methods. We isolated islets from 10 human pancreata and measured the expression of Bax mRNA and Bcl-2 mRNA by real-time quantitative polymerase chain reaction; islet and pancreas expression of Bax, Bcl-2, activated caspase-3, and cleaved poly (ADP-ribose) polymerase were also assessed by immunohistochemistry. Islet cell apoptosis was evaluated by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assay and by flow cytometry. Results. The mean (±SE) level of Bax mRNA was 336±79 copies per nanogram of total RNA, and the level of Bcl-2 mRNA was 36±10 (P=0.001). A positive correlation existed between islet expression of Bax mRNA and Bcl-2 mRNA (P=0.001). The islet Bax to Bcl-2 ratio was 10.8±1.3 and 1.71±0.3 for the spleens (P=0.0001). Bax mRNA (P=0.04), but not Bcl-2 mRNA, was expressed at a higher level in islets compared with spleens. Human islets contained large numbers of cells expressing Bax protein, whereas only infrequent islet cells expressed Bcl-2 protein, activated caspase-3, and poly (ADP-ribose) polymerase. The apoptotic index was 5% by TUNEL assay, and the percentage of apoptotic islet cells was 9.7±2.5% by flow cytometry. Sections of human pancreas before islet isolation showed islet staining for Bax but not Bcl-2. Conclusions. Our finding that isolated human islets express Bax at a higher level compared with Bcl-2 suggests a molecular mechanism for islet cell death by apoptosis. We hypothesize that reducing islet expression of Bax, or regulating its activation, will help preserve islet cell mass after islet transplantation.
AB - Background. Apoptosis is a well-documented pathway for islet cell death. One potential mechanism is overexpression of death-promoting Bax compared with antiapoptotic Bcl-2 in islets. Methods. We isolated islets from 10 human pancreata and measured the expression of Bax mRNA and Bcl-2 mRNA by real-time quantitative polymerase chain reaction; islet and pancreas expression of Bax, Bcl-2, activated caspase-3, and cleaved poly (ADP-ribose) polymerase were also assessed by immunohistochemistry. Islet cell apoptosis was evaluated by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assay and by flow cytometry. Results. The mean (±SE) level of Bax mRNA was 336±79 copies per nanogram of total RNA, and the level of Bcl-2 mRNA was 36±10 (P=0.001). A positive correlation existed between islet expression of Bax mRNA and Bcl-2 mRNA (P=0.001). The islet Bax to Bcl-2 ratio was 10.8±1.3 and 1.71±0.3 for the spleens (P=0.0001). Bax mRNA (P=0.04), but not Bcl-2 mRNA, was expressed at a higher level in islets compared with spleens. Human islets contained large numbers of cells expressing Bax protein, whereas only infrequent islet cells expressed Bcl-2 protein, activated caspase-3, and poly (ADP-ribose) polymerase. The apoptotic index was 5% by TUNEL assay, and the percentage of apoptotic islet cells was 9.7±2.5% by flow cytometry. Sections of human pancreas before islet isolation showed islet staining for Bax but not Bcl-2. Conclusions. Our finding that isolated human islets express Bax at a higher level compared with Bcl-2 suggests a molecular mechanism for islet cell death by apoptosis. We hypothesize that reducing islet expression of Bax, or regulating its activation, will help preserve islet cell mass after islet transplantation.
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U2 - 10.1097/00007890-200212150-00003
DO - 10.1097/00007890-200212150-00003
M3 - Article
C2 - 12490780
AN - SCOPUS:0037115309
SN - 0041-1337
VL - 74
SP - 1489
EP - 1496
JO - Transplantation
JF - Transplantation
IS - 11
ER -