Hsp70 attenuates hypoxia/reoxygenation-induced activation of poly(ADP-ribose) synthetase in the nucleus of adult rat cardiomyocytes.
Effects of heat shock protein 70 (Hsp70) translocated to nuclear fraction on hypoxia/reoxygenation injury was examined by using adult cardiomyocytes isolated from rats. Cardiomyocytes were exposed to heat shock at 42 degrees C for 15 min (HS group), and then incubated at 37 degrees C for 6-24 h. Hsp70 production increased and the protein translocated from cytosol to nucleus. The maximum level of Hsp70 in the nuclear fraction was observed 12 h after HS. When cardiomyocytes without exposure to HS (nHS group) were subjected to 120 min hypoxia/15 min reoxygenation (Hypo/Reoxy), post-hypoxic cell viability was approximately 25% of the pre-hypoxic value. A rise in poly(ADP-ribose) synthetase (PARS) activity in the nuclear fraction was observed in nHS group, associated with an increase in polyADP-ribosylated protein. In contrast, post-hypoxic cell viability of HS group was approximately 60% of the pre-hypoxic value. Hypo/reoxy-induced rise in PARS activity and increase in polyADP-ribosylated protein were attenuated in HS group. To confirm the relationship between an increase in cell viability after Hypo/Reoxy and attenuation of PARS activation, cardiomyocytes without exposure to HS were subjected to Hypo/Reoxy in the presence of 1 mM 3-aminobenzamide, an inhibitor of PARS. Treatment of cells with 3-aminobenzamide attenuated Hypo/ Reoxy-induced decrease in cell viability. These results suggest that Hsp70 translocated into nucleus after HS may attenuate PARS activation during Hypo/Reoxy, leading to the cytoprotection of cardiomyocytes against Hypo/Reoxy injury.
Tanonaka
Kouichi
K
Department of Pharmacology, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo, Japan.
Toga
Wakako
W
Takahashi
Masaya
M
Kawana
Ken-ichiro
K
Miyamoto
Yuki
Y
Yoshida
Hiroyuki
H
Takeo
Satoshi
S
D021581:Active Transport, Cell Nucleus; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism*; D002470:Cell Survival; D003402:Creatine Kinase / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D006358:Hot Temperature; D000860:Hypoxia; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature; D013997:Time Factors
D001549:Benzamides; D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; C025160:3-aminobenzamide; D011065:Poly(ADP-ribose) Polymerases; D003402:Creatine Kinase; D010100:Oxygen