Treatment of Normal Human Keratinocytes with 2,3,7,8-Tetrachlorodibenzo-p-dioxin Causes a Reduction in Cell Number, but No Increase in Apoptosis

2001 ◽  
Vol 175 (2) ◽  
pp. 114-120 ◽  
Author(s):  
J.A. Loertscher ◽  
C.S. Sadek ◽  
B.L. Allen-Hoffmann
Keyword(s):  
Human Keratinocytes ◽  
Cell Number ◽  
Normal Human Keratinocytes ◽  
Normal Human ◽  
Tetrachlorodibenzo P Dioxin

scholarly journals UVB-mediated activation of p38 mitogen-activated protein kinase enhances resistance of normal human keratinocytes to apoptosis by stabilizing cytoplasmic p53

2002 ◽  
Vol 365 (1) ◽  
pp. 133-145 ◽  
Author(s):  
Nadine CHOUINARD ◽  
Kristoffer VALERIE ◽  
Mahmoud ROUABHIA ◽  
Jacques HUOT
Keyword(s):  
Adaptive Response ◽  
Human Keratinocytes ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Dominant Negative Mutant ◽  
Normal Human Keratinocytes ◽  
Mitogen Activated Protein ◽  
Normal Human ◽  
Induced Apoptosis ◽  
Negative Mutant

Human keratinocytes respond to UV rays by developing a fast adaptive response that contributes to maintaining their functions and survival. We investigated the role of the mitogen-activated protein kinase pathways in transducing the UV signals in normal human keratinocytes. We found that UVA, UVB or UVC induced a marked and persistent activation of p38, whereas c-Jun N-terminal kinase or extracellular signal-regulated kinase were less or not activated respectively. Inhibition of p38 activity by expression of a dominant-negative mutant of p38 or with SB203580 impaired cell viability and led to an increase in UVB-induced apoptosis. This sensitization to apoptosis was independent of caspase activities. Inhibition of p38 did not sensitize transformed HaCaT keratinocytes to UVB-induced apoptosis. In normal keratinocytes, expression of a dominant-negative mutant of p53 increased UVB-induced cell death, pointing to a role for p53. In these cells, UVB triggered a p38-dependent phosphorylation of p53 on Ser-15. This phosphorylation was associated with an SB203580-sensitive accumulation of p53, even in the presence of a serine phosphatase inhibitor. Accumulated p53 was localized mainly in the cytoplasm, independently of CRM1 nuclear export. In HaCaT cells, p53 was localized exclusively in the nucleus and its distribution and level were not affected by UVB or p38 inhibition. However, UVB induced an SB203580-insensitive phosphorylation on Ser-15 of mutated p53. Overall, our results suggest that, in normal human keratinocytes, protection against UVB depends on p38-mediated phosphorylation and stabilization of p53 and is tightly associated with the cytoplasmic sequestration of wild-type p53. We conclude that the p38/p53 pathway plays a key role in the adaptive response of normal human keratinocytes against UV stress.

C2-ceramide triggers a BCL-2 mediated apoptosis in normal human keratinocytes

1998 ◽  
Vol 16 ◽  
pp. S75
Author(s):  
A Di Nardo ◽  
L Benassi ◽  
C Magnoni ◽  
C Pincelli ◽  
A Giannetti
Keyword(s):  
Human Keratinocytes ◽  
Normal Human Keratinocytes ◽  
Normal Human
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