Caveolin-1/PTRF upregulation constitutes a mechanism for mediating p53-induced cellular senescence: implications for evidence-based therapy of delayed wound healing in diabetes.
A heightened state of oxidative stress and senescence of fibroblasts constitute potential therapeutic targets in nonhealing diabetic wounds. Here, we studied the underlying mechanism mediating diabetes-induced cellular senescence using in vitro cultured dermal fibroblasts and in vivo circular wounds. Our results demonstrated that the total antioxidant capacity and mRNA levels of thioredoxinreductase and glucose-6-phosphate dehydrogenase as well as the ratio of NADPH/NADP were decreased markedly in fibroblasts from patients with type 2 diabetes (DFs). Consistent with this shift in favor of excessive reactive oxygen species, DFs also displayed a significant increase in senescence-associated β-galactosidase activity and phospho-γ-histone H2AX (pH2AX) level. Moreover, the ability of PDGF to promote cell proliferation/migration and regulate the phosphorylation-dependent activation of Akt and ERK1/2 appears to be attenuated as a function of diabetes. Mechanistically, we found that diabetes-induced oxidative stress upregulated caveolin-1 (Cav-1) and PTRF expression, which in turn sequestered Mdm2 away from p53. This process resulted in the activation of a p53/p21-dependent pathway and the induction of premature senescence in DFs. Most of the aforementioned oxidative stress and senescence-based features observed in DFs were recapitulated in a 10-day-old diabetic wound. Intriguingly, we confirmed that the targeted depletion of Cav-1 or PTRF using siRNA- or Vivo-Morpholino antisense-based gene therapy markedly inhibited diabetes/oxidative stress-induced premature senescence and also accelerated tissue repair in this disease state. Overall, our data illuminate Cav-1/PTRF-1 as a key player of a novel signaling pathway that may link a heightened state of oxidative stress to cellular senescence and impaired wound healing in diabetes.
Department of Pharmacology and Toxicology, Kuwait University, Safat, Kuwait;
Milad S
MS
Bitar
Samy M
SM
Abdel-Halim
Fahd
F
Al-Mulla
D000818:Animals; D051242:Caveolin 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D016922:Cellular Senescence; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D020868:Gene Silencing; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D058990:Molecular Targeted Therapy; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D015398:Signal Transduction; D012867:Skin / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D013880:Thioredoxin-Disulfide Reductase / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation; D014945:Wound Healing / Q000187:drug effects
C495537:Cav1 protein, rat; D051242:Caveolin 1; C506791:Cavin1 protein, rat; D008565:Membrane Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D005954:Glucosephosphate Dehydrogenase; D013880:Thioredoxin-Disulfide Reductase
polymerase I and transcript release factor