Increase in ultraviolet sensitivity by overexpression of calpastatin in ultraviolet-resistant UVr-1 cells derived from ultraviolet-sensitive human RSa cells

Abstract

Human RSa cells are highly sensitive to apoptotic-like cell death by ultraviolet irradiation (UV) while UV r -1 cells are their variant with an increased resistance to UV. Three days after UV at 10 J/m 2 , the viability of RSa cells was approximately 17% while that of UV r -1 cells was 65%. This different survival might reflect apoptotic cell death since apoptosis-specific DNA ladder was more clearly observed in RSa cells than in UV r -1 cells after UV. Addition of ALLN/calpain inhibitor I to the culture medium after UV resulted in similar survival (14 ± 18%) between RSa and UV r -1 cells. Immunoblot analysis showed down-regulation of protein kinase Cy, Src, Bax and m-calpain after UV was more prominent in UV r -1 than in RSa cells. Activated m-calpain appeared within 1 h post-UV only in UV r -1 cells. The expression of calpastatin, a specific endogenous inhibitor of calpain, was higher in RSa than in UV r -1 cells. To further examine the role of calpain in UV-induced cell death, cDNA of human calpastatin was transfected into UV r -1 cells. The results showed that overexpression of calpastatin suppressed down-regulation of Src, m-calpain and Bax. Concomitantly, colony survival after UV was reduced in calpastatin-transfected cells as compared to vector control cells. Our results suggest that activation of calpain might account for, at least in part, the lower susceptibility to UVinduced cell death in UV r -1 cells. Cell Death and Differentiation (2000) 7, 531 ± 537.

Involvement of human heat shock protein 90α in nicotine‐induced apoptosis

“…Both RSa and XP2OS cells show high sensitivity to the lethal effect of UV. 7,34 UVAP-1 cells are also sensitive to UV lethality as well as the parent RSa cells, although they are more resistant to UV mutagenicity than RSa cells. 8 Thus, cellular susceptibility to UV lethality may not be causally related with that to nicotine-induced apoptosis among the 3 cell strains tested.…”

“…In the present study, we utilized a human RSa cell strain and its derivative, the UVAP-1 cell line. RSa cells are highly sensitive to apoptosis induced by various agents 7 and were found here to be susceptible to nicotine-induced apoptosis. UVAP-1 cells were established as cells with increased levels of protease activity after UV irradiation 8 and were found here to have increased resistance to nicotine-induced apoptosis.…”

Leupeptin‐sensitive proteases involved in cell survival after X‐ray irradiation in human RSa cells

“…We therefore suggested that an increase in antipain-sensitive protease activity by UV irradiation is involved in the suppression of cell mutability. Furthermore, we recently found that an increase in protease activity promptly after UV irradiation was associated with changes in the resistance of RSa cells (Sugita et al, 2001;Hiwasa et al, 2000). It is suggested that the increase in protease activity by UV irradiation is involved in the suppression of UV cell-killing.…”

Elevated Levels of Autoantibodies against ATP2B4 and BMP-1 in Sera of Patients with Atherosclerosis-related Diseases

“…After incubation with horseradish peroxidase-conjugated secondary antibody, immunoreactivity was detected with the Immobilon (Merck Millipore, Darmstadt, Germany) as previously described [18,22].…”