title: Drosophila mixed lineage kinase/slipper, a missing biochemical link in Drosophila JNK signaling.
abstract: Mixed lineage kinases (MLKs) belong to the family of mitogen activated protein kinase kinase kinase (MAPKKK) and cause neuronal cell death mediated through c-Jun, N-terminal kinase (JNK) pathway. Recently, genetic studies in Drosophila revealed the presence of an MLK termed slipper (slpr). However, its biochemical features like physiological substrate, role in different MAPK pathways and developmental and tissue-specific expression pattern were not reported. Here, we report cDNA cloning, expression analysis and biochemical characterization of a Drosophila mixed lineage kinase (dMLK) that is also known as slipper. The protein structure analysis of dMLK/slipper revealed, in addition to the conserved domains, a stretch of glutamine in the amino terminus and an asparagine-threonine stretch at the carboxy-terminus. In situ hybridization and reverse transcriptase polymerase chain reaction (RT-PCR) analysis revealed that dMLK is expressed in early embryonic stages, adult brain and thorax. Ectopic expression of dMLK either in Drosophila S2 or in mammalian HEK293 cells leads to activation of JNK, p38 and extracellular signal regulated kinase (ERK) pathways. Further, dMLK directly phosphorylates Hep, dMKK4 and also their mammalian counterparts, MKK7 and SEK1, in an in vitro kinase assay. Taken together, our results provide for the first time a comprehensive expression profile and new biochemical insight of dMLK/slipper.
authors.affiliation: The Division of Molecular Cardiology, Cardiovascular Research Institute, College of Medicine, The Texas A&M University System HSC, 1901 South 1st St. Bldg.162, Temple, TX 76504, USA.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Sathyanarayana
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Barthwal
authors.forename: Mary Ellen
authors.initials: ME
authors.lastname: Lane
authors.forename: Summer F
authors.initials: SF
authors.lastname: Acevedo
authors.forename: Efthimios M C
authors.initials: EM
authors.lastname: Skoulakis
authors.forename: Andreas
authors.initials: A
authors.lastname: Bergmann
authors.forename: Ajay
authors.initials: A
authors.lastname: Rana
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004330:Drosophila / Q000196:embryology / Q000201:enzymology*; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004789:Enzyme Activation; D017403:In Situ Hybridization; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020930:MAP Kinase Kinase Kinases / Q000096:biosynthesis / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D029721:Drosophila Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C447860:slpr protein, Drosophila; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases