Premium
Activation of the JAK/STAT pathway by ceramide in cultured human fibroblasts
Author(s) -
Mazière Cécile,
Conte Marie-Alix,
Mazière Jean-Claude
Publication year - 2001
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(01)02977-5
Subject(s) - phosphorylation , janus kinase , stat protein , microbiology and biotechnology , kinase , ceramide , mapk/erk pathway , chemistry , signal transduction , stat3 , biology , biochemistry , apoptosis
Endogenous ceramide (CER) was generated by treatment of cultured fibroblasts with sphingomyelinase (SMase) from Bacillus cereus . A 30 min treatment with 0.1–0.3 U/ml SMase induced a dose‐dependent increase in the intracellular level of CER. The activation of the transcription factors signal transducer and activator of transcription (STAT) 1 and STAT3 by SMase was investigated by determination of the phosphorylation state by immunoblot, and of DNA binding activity by electrophoretic mobility shift assay. SMase treatment induced a dose‐dependent Tyr‐phosphorylation of STAT1/3. SMase also enhanced STAT1/3 DNA binding activity in a dose‐dependent manner. Concomitantly, SMase enhanced the Tyr‐phosphorylation of Janus kinase (JAK) 2, a Tyr‐kinase localized upstream of STATs in the JAK/STAT pathway. The Tyr‐kinase inhibitor genistein and the JAK inhibitor AG490 both prevented JAK2 Tyr‐phosphorylation, together with STAT1 and STAT3 Tyr‐phosphorylation and binding activity. The SMase‐induced increase in STAT1/3 binding activity was prevented by methyl‐β‐cyclodextrin, a cholesterol binding agent that causes a loss of compartmentalization of the molecules located in caveolae. This increase was also prevented by the MEK inhibitor PD98059, thus demonstrating the role of the MEK/ERK pathway in this system. Besides ERK, SMase activated other signaling kinases such as JNK and p38. Exogenous natural CER also activated STAT1/3 binding activity, which indicates that most probably, endogenous CER is the second messenger involved in the effect of SMase. These results describe a crosstalk between the SMase/CER and the JAK/STAT signaling pathways and include JAK2 within the range of CER‐activated intracellular kinases.