Associate Professor

Ph.D.: University of Houston
Post-doctoral Training: Baylor College of Medicine

Center for Molecular Neurobiology
The Ohio State University
168 Rightmire Hall
1060 Carmack Road
Columbus, OH 43210

Phone: 614-292-8173
Fax: 614-292-5379
E-mail: zhu.55@osu.edu

Link to NLM & NIH PubMed publications list for Mike Xi Zhu (last 10 years)

• Signal transduction
• G protein and G protein-coupled receptors
• Ca²⁺ signaling and Ca²⁺ channels
• Structure and function of TRP channels
• Molecular mechanisms of learning

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Research Description:

Calcium ions play important roles in the life and death of animal cells. Ca²⁺ enters cells through Ca²⁺ permeable channels. Our research focuses on the structure, mechanism of activation, and functional regulation of Ca²⁺ channels. These include 1) the Canonical Transient Receptor Potential (TRPC) channels, which are postulated to be responsible for capacitative Ca²⁺ entry activated following the stimulation of cell surface receptors and concomitant Ca²⁺ release from internal stores, 2) TRPV and TRPM channels involved in temperature, pH and osmolarity sensing, and 3) neuronal voltage-gated Ca²⁺ channels involved in synaptic transmission and action potential firing. Our recent work shows that TRPC channels are activated through direct physical interactions with intracellular Ca²⁺ release channels and the activation is inhibited by calmodulin. We have identified several TRPC binding domains from the Ca²⁺ release channels and multiple calmodulin binding sites from TRPC, TRPV and TRPM proteins. The functional roles of these binding sites are examined after site-directed mutagenesis and heterologous expression in mammalian cells using intracellular fluorescence Ca²⁺ imaging and electrophysiological techniques. Second, we have demonstrated how TRPC channels are clustered and connected with the actin cytoskeleton. The connection with the cytoskeletal network is important for the functional regulation of these channels. Furthermore, in collaboration with Dr. John Oberdick, we have demonstrated that a small cerebellar Purkinje cell protein, L7, is a regulator of the P/Q-type Ca²⁺ channels. Our data suggest that the regulatory effects of L7 on the Ca²⁺ channels differ based on the concentration of L7 proteins and the effects are mediated by heterotrimeric G proteins. Because L7 has been implicated in the developmental and functional plasticity of Purkinje cells, our results suggest a novel mechanism of how learning and memory may be expressed and maintained in these neurons.

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Techniques and Models:

• Molecular biology
• Protein-protein interactions
• Molecular anatomy
• Heterologous expression
• Ion channel Physiology