Recent investigations have identified a new signal transduction pathway, termed the sphingomyelin pathway, that may mediate the action of tumor necrosis factor (TNF)-alpha and interleukin 1 (IL-1) Beta. This pathway is initiated by hydrolysis of plasma membrane sphingomyelin to ceramide by the action of a neutral sphingomyelinase. Ceramide functions as a second messenger stimulating a Ser/Thr proteins kinase termed ceramide- activated protein kinase to transduce the signal. Three lines of evidence support this notion. Firstly, the sphingomyelin pathway is activated within seconds to minutes by TNF in HL-60 cells and by IL-1 in human dermal fibroblasts and mouse EL4 T helper cells. Secondly, cell- permeable ceramide analogs bypass receptor activation and directly mimic cytokine action. Thirdly, the effects of TNF and IL-1 on this cascade have been reconstituted in cell-free extracts indicating tight coupling of this pathway to the respective receptors. This grant proposal focusses on the elucidation of the role of ceramide-activated protein kinase in this signaling cascade. Until now, this activity has only been defined as a Mg2+ dependent, membrane-bound activity capable of phosphorylating a peptide derived from this amino acid sequenced surrounding Thr669 of the epidermal growth factor receptor. This is the same site recognized by mitogen-activated protein (MAP) kinases (also known as extracellular signal-regulated protein kinases). Hence, ceramide-activated protein kinase may belong to an emerging family of proline-directed Ser/Thr protein kinases, which includes MAP and cdc2 kinases. These kinases recognize substrates containing the minimal motif, X-Thr/Ser-Pro-X, where the phosphoacceptor site is followed on the carboxyl-terminus by a proline residue and X can be any amino acid. This grant application has three goals: (1) To define the structural determinants for substrates recognition by ceramide-activated protein kinase and for ceramide stimulation, and determine the intracellular localization of enzyme activity; (2) to purify ceramide-activated protein kinase; and (3) to define how known antagonist of TNF action might act upon the sphingomyelin pathway and, in particular, ceramide-activated protein kinase. It is our belief that ceramide-activated protein kinase represents a new target for pharmacologic intervention in TNF and IL-1 action. Hence, the title of this application has been changed to reflect this emphasis. Hopefully, these studies will begin the process necessary for testing this hypothesis.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA042385-10
Application #
2090707
Study Section
Medical Biochemistry Study Section (MEDB)
Project Start
1986-04-01
Project End
1998-03-31
Budget Start
1995-04-01
Budget End
1996-03-31
Support Year
10
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
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Zhang, Jianjun; Zafrullah, Mohammad; Yang, Xia et al. (2008) Downregulation of KSR1 in pancreatic cancer xenografts by antisense oligonucleotide correlates with tumor drug uptake. Cancer Biol Ther 7:1490-5
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Joseph, C K; Byun, H S; Bittman, R et al. (1993) Substrate recognition by ceramide-activated protein kinase. Evidence that kinase activity is proline-directed. J Biol Chem 268:20002-6
Mathias, S; Younes, A; Kan, C C et al. (1993) Activation of the sphingomyelin signaling pathway in intact EL4 cells and in a cell-free system by IL-1 beta. Science 259:519-22

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