title: p35/cyclin-dependent kinase 5 phosphorylation of ras guanine nucleotide releasing factor 2 (RasGRF2) mediates Rac-dependent Extracellular Signal-regulated kinase 1/2 activity, altering RasGRF2 and microtubule-associated protein 1b distribution in neurons.
abstract: Cyclin-dependent kinase 5 (Cdk5) is a proline-directed kinase the activity of which is dependent on association with its neuron-specific activators, p35 and p39. Cdk5 activity is critical for the proper formation of cortical structures and lamination during development. In the adult nervous system, Cdk5 function is implicated in cellular adhesion, dopamine signaling, neurotransmitter release, and synaptic activity. In addition, Cdk5 is also involved in "cross-talk" with other signal transduction pathways. To further examine its involvement in cross-talk with other pathways, we identified proteins that interacted with p35 using the yeast two-hybrid system. We report here that p35 associates with Ras guanine nucleotide releasing factor 2 (RasGRF2) in coimmunoprecipitation and colocalization studies using transfected cell lines as well as primary cortical neurons. Additionally, Cdk5 phosphorylates RasGRF2 both in vitro and in vivo, leading to a decrease in Rac-guanidine exchange factor activity and a subsequent reduction in extracellular signal-regulated kinase 1/2 activity. We show that p35/Cdk5 phosphorylates RasGRF2 on serine737, which leads to an accumulation of RasGRF2 in the neuronal cell bodies coinciding with an accumulation of microtubule-associated protein 1b. The membrane association of p35 and subsequent localization of Cdk5 activity toward RasGRF2 and Rac provide insights into important cellular signaling processes that occur at the membrane, resulting in downstream effects on signal transduction cascades.
authors.affiliation: Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Sashi
authors.initials: S
authors.lastname: Kesavapany
authors.forename: Niranjana
authors.initials: N
authors.lastname: Amin
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Zheng
authors.forename: Ruchika
authors.initials: R
authors.lastname: Nijhara
authors.forename: Howard
authors.initials: H
authors.lastname: Jaffe
authors.forename: Ram
authors.initials: R
authors.lastname: Sihag
authors.forename: J Silvio
authors.initials: JS
authors.lastname: Gutkind
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
authors.forename: Ashok
authors.initials: A
authors.lastname: Kulkarni
authors.forename: Philip
authors.initials: P
authors.lastname: Grant
authors.forename: Harish C
authors.initials: HC
authors.lastname: Pant
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics / Q000502:physiology; D019556:COS Cells / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006224:Cricetinae; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection; D020798:Two-Hybrid System Techniques; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020663:ras Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
chemical_list: D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; C504490:RASGRF2 protein, human; C504491:Rasgrf2 protein, mouse; C504492:Rasgrf2 protein, rat; C085284:microtubule-associated protein 1B; C089495:neuronal Cdk5 activator (p25-p35); D020663:ras Guanine Nucleotide Exchange Factors; D051360:Cyclin-Dependent Kinase 5; C495905:CDK5 protein, human; C495906:Cdk5 protein, mouse; C495907:Cdk5 protein, rat; D018844:Cyclin-Dependent Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020744:rac GTP-Binding Proteins; D018631:ras Proteins