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Alexey G. Ryazanov, Ph.D.

Professor
Robert Wood Johnson Medical School  
Office: RWJMS/RT, Room 443  

Phone: (732) 235-5526  
Fax: (732) 235-4073  
E-mail: alexey.ryazanov@rutgers.edu

 

Research Interest:

Alpha-kinases, channel-kinases and cell signaling

 

Research Description:

We have recently discovered a new class of protein kinases -- alpha-kinases. Alpha-kinases play an important role in the control of protein synthesis, cell growth and differentiation. Two alpha-kinases that we recently identified represent a novel type of signaling molecule that consists of a protein kinase fused to an ion-channel. Why would a kinase and ion-channel be contained in one molecule? Is the channel activity controlled by the kinase, or is the kinase controlled by ion flow through the channel? We are using molecular biological, biochemical, and bioinformatic approaches as well as transgenic animals to investigate the structure and function of these fascinating molecules.

An online database of all known alpha-kinases and related links is available. (New Version) (Old Version)

TRPM7 channel-kinase: study of the kinase domain and identification of substrates. TRPM7, a member of the TRP family of ion channels, is an unusual bifunctional molecule consisting of an ion channel fused to a protein kinase domain. TRPM7 channel has been characterized using electrophysiological techniques, however, the function of the kinase domain is not fully understood. To identify the signaling pathways of TRPM7 kinase we conducted a systematic search of substrates for TRPM7 kinase. In order to identify substrates for TRPM7 kinase we used cell fractionation, phosphorylation with purified recombinant TRPM7 kinase and subsequent peptide mass fingerprinting by MALDI-TOF mass spectrometry.

Previously we have discovered the first endogenous target of TRPM7 kinase, annexin 1. Annexin 1 is a calcium and phospholipid binding immunomodulatory protein implicated in the regulation of membrane and cytoskeleton dynamics. We continued to study annexin 1 and we have investigated in detail how phosphorylation of annexin 1 by TRPM7 kinase affect its physiological function. In the cell annexin 1 can interact with membranes; however it does not affect interaction with S100A11 protein. Therefore, this phosphorylation can regulate distribution of annexin 1 between membranes and S100A11 protein in cells, and thus affect function of annexin 1 in vivo.

In addition to annexin 1 we have also identified beta-actin and tropomodulin 1 as substrates for TRPM7 kinase. We have determined sites of phosphorylation for TRPM7 kinase in these protein. Beta-actin is phosphorylated at Ser33 and Tropomodulin 1 is phosphorylated at Ser2 and Thr54. We have analyzed the effect of phosphorylation of these proteins by TRPM7 kinase on their function in cell cultures. We found that phosphorylation of tropomodulin 1 at Thr54 affect its actin-capping activity. We have also found that phosphorylation of beta-actin at Ser33 can regulate assembly of actin filaments.

We have continued our study of myosin ll phosphorylation by TRPM7 kinase. We have investigated whether TRPM6 and TRPM7 kinases phosphorylate myosin ll on different residues. While these channels share electrophysiological properties and cellular functions, TRPM6 and TRPM7 are non-redundant genes raising the possibility that the kinases have distinct substrates. We found that TRPM6 and TRPM7 phosphorylate the assembly domain of myosin llA, llB and llC on identical residues. Whereas phosphorylation of myosin llA is restricted to the coiled domain. TRPM6 and TRPM7 also phosphorylate the non-helical tails of myosin llB and llC. We have found that TRPM7 does not phosphorylate eukaryotic elongation factor-2 (eEF-2) and myosin ll is a poor substrate for eEF-2 kinase. Overall, our results suggest that TRPM7 kinase modulate cytoskeleton dynamics and regulates cell motility.