HSP70 and EndoG modulate cell death by heat in human skin keratinocytes in vitro.
We examined how young and old keratinocytes died from heat stress in vitro. We found that keratinocyte cell death was not due to oxidative stress as neither Mn-SOD nor Cu-Zn-SOD was produced in either young or old heated keratinocytes. Instead, analysis of the anti-apoptotic factors, Bcl2 and HSP70, and the pro-apoptotic factors, caspase 3, caspase 8, Apaf-1, cytochrome c, AIF, and EndoG, indicated that keratinocyte cell death occurred via the caspase-independent EndoG apoptotic pathway. We found that both young and old keratinocytes died via the same pathway, and that we could specifically reduce both young and old keratinocyte death by addition of the EndoG inhibitor NEM. Further analysis suggested that the difference between young and old keratinocyte death was due to the synthesis of HSP70 protein, with the increase in response to heat more pronounced in young keratinocytes than in old keratinocytes. When we inhibited HSP70 by adding quercetin, death was increased in both young and old keratinocytes, but more so in old keratinocytes. These data suggest that old keratinocytes may die more readily than young keratinocytes when heated because they synthesize HSP70 at a lower efficiency. Such findings suggest that HSP70 production may be age-dependent.
Chinnathambi
Sathivel
S
Department of Anatomy and Cell Biology, The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
Tomanek-Chalkley
Ann
A
Bickenbach
Jackie R
JR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D006979:Hyperthermia, Induced / Q000009:adverse effects; D015603:Keratinocytes / Q000201:enzymology / Q000473:pathology*; D008875:Middle Aged; D011794:Quercetin / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism
C494829:AIFM1 protein, human; D000975:Antioxidants; D051033:Apoptosis Inducing Factor; D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; D011794:Quercetin; D013482:Superoxide Dismutase; D004706:Endodeoxyribonucleases; C052391:endonuclease G; D005033:Ethylmaleimide