Activation of the Drosophila MLK by ceramide reveals TNF-alpha and ceramide as agonists of mammalian MLK3.
Mixed lineage kinases (MLKs) are MAPKKK members that activate JNK and reportedly lead to cell death. However, the agonist(s) that regulate MLK activity remain unknown. Here, we demonstrate ceramide as the activator of Drosophila MLK (dMLK) and identify ceramide and TNF-alpha as agonists of mammalian MLK3. dMLK and MLK3 are activated by a ceramide analog and bacterial sphingomyelinase in vivo, whereas a low nanomolar concentration of natural ceramide activates them in vitro. Specific inhibition of dMLK and MLK3 significantly attenuates activation of JNK by ceramide in vivo without affecting ceramide-induced p38 or ERK activation. In addition, TNF-alpha also activates MLK3 and evidently leads to JNK activation in vivo. Thus, the ceramide serves as a common agonist of dMLK and MLK3, and MLK3 contributes to JNK activation induced by TNF-alpha.
Sathyanarayana
Pradeep
P
The Division of Molecular Cardiology, Cardiovascular Research Institute, College of Medicine, The Texas A&M University System HSC, 76504, Temple, TX 77030, USA.
Barthwal
Manoj K
MK
Kundu
Chanakya N
CN
Lane
Mary Ellen
ME
Bergmann
Andreas
A
Tzivion
Guri
G
Rana
Ajay
A
D000818:Animals; D002460:Cell Line; D002518:Ceramides / Q000494:pharmacology*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000502:physiology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells; D007668:Kidney; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D008322:Mammals; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
D002518:Ceramides; D029721:Drosophila Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D014409:Tumor Necrosis Factor-alpha; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11; C101954:N-caproylsphingosine; C447860:slpr protein, Drosophila