title: Insulin-like growth factor-1 preconditioning accentuates intrinsic survival mechanism in stem cells to resist ischemic injury by orchestrating protein kinase cα-erk1/2 activation.
abstract: OBJECTIVE
  To test our hypothesis that the intrinsic molecular mechanism in stem cells for adaptation to ischemia is accentuated by preconditioning with insulin-like growth factor (IGF-1).
  
  
  RESULTS
  Bone marrow Sca-1(+) cells were exposed to oxygen and glucose deprivation (OGD) for up to 12 h. Erk1/2 was activated in Sca-1(+) cells under OGD which was blocked by MEK inhibitor (PD98059) and resulted in accelerated cell death. Moreover, elevated intracellular calcium with concomitant activation of protein kinase C (PKC) was observed under OGD. Pretreatment with nifedipine or dantrolene reduced cellular calcium, abrogated PKC and Erk1/2 activation, and increased cytotoxicity. Treatment with phorbol 12-myristate 13-acetate (PMA) for 30 min (short-term) activated Erk1/2, whereas 12 h (long-term) PMA treatment abrogated PKCα, reduced Erk1/2 activation and significantly increased cell death under OGD. These results were confirmed by loss-of-function studies using PKCα and Erk1/2 specific small interfering RNA. Gain-of-function studies with PKCα plasmid transfection improved cell survival under OGD. Preconditioning with 100 nM IGF-1 accentuated the intrinsic mechanism of resistance of the cells to ischemia via Erk1/2 activation and improved their survival under OGD as well as post-transplantation in an experimentally infarcted heart.
  
  
  METHODS
  Strategies to target intrinsic survival mechanism in stem cells by growth factor preconditioning to enhance their survival via activation of PKCα and Erk1/2 are innovative.
  
  
  CONCLUSIONS
  Intracellular calcium elevation under OGD activated PKCα and Erk1/2 as a part of the intrinsic prosurvival mechanism that was accentuated during preconditioning with IGF-1 to protect Sca-1(+) cells from ischemic injury.
authors.affiliation: Department of Pathology, University of Cincinnati, Ohio, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Lu
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ashraf
authors.forename: Khawaja Husnain
authors.initials: KH
authors.lastname: Haider
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D015687:Cell Hypoxia; D002470:Cell Survival; D002478:Cells, Cultured; D019610:Cytoprotection; D004789:Enzyme Activation; D005260:Female; D005947:Glucose / Q000172:deficiency; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009203:Myocardial Infarction / Q000473:pathology / Q000628:therapy; D017202:Myocardial Ischemia / Q000473:pathology / Q000628:therapy; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology
chemical_list: D000950:Antigens, Ly; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; C519530:insulin-like growth factor-1, mouse; D007334:Insulin-Like Growth Factor I; D051571:Protein Kinase C-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D005947:Glucose; D002118:Calcium