Anti-Cdk5: Rabbit Cyclin-Dependent Kinase 5 Antibody

BACKGROUND Cdks (cyclin-dependent kinases) are heteromeric serine/threonine kinases that control progression through the cell cycle in concert with their regulatory subunits, the cyclins. Although there are 12 different cdk genes, only 5 have been shown to directly drive the cell cycle (Cdk1, -2, -3, -4, and -6).¹ Following extracellular mitogenic stimuli, cyclin D gene expression is upregulated. Cdk4 forms a complex with cyclin D and phosphorylates Rb protein, leading to liberation of the transcription factor E2F. E2F induces transcription of genes including cyclins A and E, DNA polymerase and thymidine kinase. Cdk4-cyclin E complexes form and initiate G1/S transition. Subsequently, Cdk1-cyclin B complexes form and induce G2/M phase transition. Cdk1-cyclin B activation induces the breakdown of the nuclear envelope and the initiation of mitosis.² Cdks are constitutively expressed and are regulated by several kinases and phosphastases, including Wee1, CDK-activating kinase and Cdc25 phosphatase. In addition, cyclin expression is induced by molecular signals at specific points of the cell cycle; leading to activation of Cdks.³ Tight control of Cdks is essential as misregulation can induce unscheduled proliferation, and genomic and chromosomal instability. Cdk4 has been shown to be mutated in some types of cancer, whilst a chromosomal rearrangement can lead to Cdk6 overexpression in lymphoma, leukemia and melanoma. Cdks are currently under investigation as potential targets for antineoplastic therapy, but as Cdks are essential for driving each cell cycle phase, therapeutic strategies that block Cdk activity are unlikely to selectively target tumor cells.⁴

 

Cdk5 is a member of the cyclin-dependent kinase family. It interacts with D1 and D3-type G1 cyclins and is probably involved in the control of the cell cycle. However, it is unique in several aspects. First, it is activated by the neural-specific non-cyclin activators p35 and p39. Secondly, Cdk5 is implicated in neuronal migration, synapse functions/maintenance, and neuronal survival. CDK5 phosphorylates a diverse list of substrates including histone H1, tau, MAP2 and NF-H and NF-M, implicating it in the regulation of a range of cellular processes from adhesion and motility, to synaptic plasticity and drug addiction. Recent evidence indicates that deregulation of this kinase is involved in the pathology of neurodegenerative diseases.⁵
 

REFERENCES  

1. Pestell, R.G. et al: Endocrine Rev. 20:501-34, 1999
2. Nurse, P.: Cell 100:71-8, 2000
3. Morgan, D. O. : Ann. Rev. Cell Develop. Biol. 13:261-91, 1997
4. McDonald, E.R. 3rd. & El-Deiry, W.S. : Int. J. Oncol. 16:871-86, 2000
5. Dhavan, R. & Tsai, L.H.: Nature Rev. Mol. Cell Biol. 2:749-59, 2001