Bcl-2-modifying factor induces renal proximal tubular cell apoptosis in diabetic mice.
This study investigated the mechanisms underlying tubular apoptosis in diabetes by identifying proapoptotic genes that are differentially upregulated by reactive oxygen species in renal proximal tubular cells (RPTCs) in models of diabetes. Total RNAs isolated from renal proximal tubules (RPTs) of 20-week-old heterozygous db/m+, db/db, and db/db catalase (CAT)-transgenic (Tg) mice were used for DNA chip microarray analysis. Real-time quantitative PCR assays, immunohistochemistry, and mice rendered diabetic with streptozotocin were used to validate the proapoptotic gene expression in RPTs. Cultured rat RPTCs were used to confirm the apoptotic activity and regulation of proapoptotic gene expression. Additionally, studies in kidney tissues from patients with and without diabetes were used to confirm enhanced proapoptotic gene expression in RPTs. Bcl-2-modifying factor (Bmf) was differentially upregulated (P<0.01) in RPTs of db/db mice compared with db/m+ and db/db CAT-Tg mice and in RPTs of streptozotocin-induced diabetic mice in which insulin reversed this finding. In vitro, Bmf cDNA overexpression in rat RPTCs coimmunoprecipated with Bcl-2, enhanced caspase-3 activity, and promoted apoptosis. High glucose (25 mmol/L) induced Bmf mRNA expression in RPTCs, whereas rotenone, catalase, diphenylene iodinium, and apocynin decreased it. Knockdown of Bmf with small interfering RNA reduced high glucose-induced apoptosis in RPTCs. More important, enhanced Bmf expression was detected in RPTs of kidneys from patients with diabetes. These data demonstrate differential upregulation of Bmf in diabetic RPTs and suggest a potential role for Bmf in regulating RPTC apoptosis and tubular atrophy in diabetes.
Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada.
Garnet J
GJ
Lau
Nicolas
N
Godin
Hasna
H
Maachi
Chao-Sheng
CS
Lo
Shyh-Jong
SJ
Wu
Jian-Xin
JX
Zhu
Marie-Luise
ML
Brezniceanu
Isabelle
I
Chénier
Joelle
J
Fragasso-Marquis
Jean-Baptiste
JB
Lattouf
Jean
J
Ethier
Janos G
JG
Filep
Julie R
JR
Ingelfinger
Viji
V
Nair
Matthias
M
Kretzler
Clemens D
CD
Cohen
Shao-Ling
SL
Zhang
John S D
JS
Chan
D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007687:Kidney Tubules, Proximal / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
D048868:Adaptor Proteins, Signal Transducing; C435486:Bmf protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D053148:Caspase 3