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Molecular and Cellular Biology, November 1998, p. 6719-6728, Vol. 18, No. 11
Cancer Pharmacology1
and
Cancer Biology,
Received 6 April 1998/Returned for modification 2 June
1998/Accepted 28 July 1998
Protein kinase C
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Inactivation of DNA-Dependent Protein Kinase by
Protein Kinase C
: Implications for Apoptosis
(PKC
) is proteolytically cleaved and
activated at the onset of apoptosis induced by DNA-damaging agents, tumor necrosis factor, and anti-Fas antibody. A role for PKC
in
apoptosis is supported by the finding that overexpression of the
catalytic fragment of PKC
(PKC
CF) in cells is associated with
the appearance of certain characteristics of apoptosis. However, the
functional relationship between PKC
cleavage and induction of
apoptosis is unknown. The present studies demonstrate that PKC
associates constitutively with the DNA-dependent protein kinase
catalytic subunit (DNA-PKcs). The results show that PKC
CF
phosphorylates DNA-PKcs in vitro. Interaction of DNA-PKcs with PKC
CF inhibits the function of DNA-PKcs to form complexes with DNA and to
phosphorylate its downstream target, p53. The results also demonstrate
that cells deficient in DNA-PK are resistant to apoptosis
induced by overexpressing PKC
CF. These findings support the
hypothesis that functional interactions between PKC
and DNA-PK
contribute to DNA damage-induced apoptosis.
*
Corresponding author. Mailing address: Cancer
Pharmacology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney St., Boston, MA 02115. Phone: (617) 632-2938. Fax: (617)
632-2934. E-mail:
Surender_Kharbanda{at}MacMailGW.dfci.harvard.edu.
Molecular and Cellular Biology, November 1998, p. 6719-6728, Vol. 18, No. 11
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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