Combined effect of tumor necrosis factor (TNF)-alpha and heat shock protein (HSP)-70 in reducing apoptotic injury in hypoxia: a cell culture study.
Studies have demonstrated neuroprotective effects of either TNF-alpha or HSP-70 in ischemia/reperfusion injury following exercise. However, the protective mechanisms involving combined effect of the two proteins, particularly in neuronal apoptosis, remain unclear. This study aims to elucidate the beneficial role of TNF-alpha and HSP-70 in the regulation of apoptotic proteins and ERK signaling in hypoxic injury. Cortical neurons from 20 Sprague-Dawley rat embryos were isolated and cultured in five groups with or without pretreatment with recombinant TNF-alpha, HSP-70 protein or both prior to hypoxic conditions: (1) control; (2) control/hypoxia; (3) TNF-alpha/hypoxia; (4) HSP-70/hypoxia and (5) TNF-alpha/HSP-70/hypoxia. Western blotting was used to detect pro- and anti-apoptotic proteins, including Bax, AIF, Bcl-xL, Bcl-2, and pERK1/2 protein. TNF-alpha and HSP-70 significantly (p<0.05) reduced the levels of pro-apoptotic proteins, Bax and AIF. Also, pretreatment of hypoxic brain tissue with TNF-alpha and HSP-70 significantly (p<0.05) enhanced the levels of anti-apoptotic protein, Bcl-xL. TNF-alpha and HSP-70 together increased Bcl-2 levels by 70%. Hypoxia caused a significant (p<0.05) increase in ERK1/2 phosphorylation levels by 224%. The most effective inhibition of ERK levels was obtained by the combined administration of TNF-alpha and HSP-70. This study suggested that TNF-alpha and HSP-70 together enhance the decrease in pro-apoptotic protein levels and the increase in anti-apoptotic protein levels in the event of neuronal hypoxia through ERK1/2 signal transduction.
Goel
Gunjan
G
Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Guo
Miao
M
Ding
Jamie
J
Dornbos
David
D
Ali
Ahmer
A
Shenaq
Mohammed
M
Guthikonda
Murali
M
Ding
Yuchuan
Y
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004622:Embryo, Mammalian; D005786:Gene Expression Regulation / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000494:pharmacology*; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
D051033:Apoptosis Inducing Factor; C494812:Bcl2l1 protein, mouse; D004338:Drug Combinations; D018840:HSP70 Heat-Shock Proteins; D018696:Neuroprotective Agents; D014409:Tumor Necrosis Factor-alpha; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D048052:Mitogen-Activated Protein Kinase 3