Publication Date
2018
Document Type
Dissertation
Committee Members
J. Ashot Kozak, Ph.D. (Advisor); Gerald M. Alter, Ph.D. (Committee Member); Dan R. Halm, Ph.D. (Committee Member); F. Javier Alvarez-Leefmans, Ph.D. (Committee Member); Kathrin Engisch, Ph.D. (Committee Member)
Degree Name
Doctor of Philosophy (PhD)
Abstract
The characteristic feature of ubiquitously expressed transient receptor potential melastatin 7 (TRPM7) protein is the presence of a C-terminal atypical kinase domain fused to a cation channel domain. Even though this protein has been implicated in a number of physiological and pathological processes, the mechanisms regulating TRPM7 channel activity are poorly understood. In the present study, regulation of TRPM7 channel by its kinase activity was investigated using the TRPM7 kinase-dead knock-in mouse (KD mouse). These mice have a point mutation Lys1646Arg in the kinase region abrogating the kinase activity. Examining TRPM7 channel activity in KD peritoneal macrophages revealed that TRPM7 kinase activity is not required for channel activity yet may reduce the number of channels functioning in an intact cell. Thus, kinase activity is dispensable for the formation of functional TRPM7 channels, in agreement with previous studies done in overexpression systems. T lymphocytes isolated from KD mice showed reduced blastogenesis, proliferation and cytokine expression upon activation, potentially due to defective up-regulation of Ca²⁺ and Mg²⁺ dependent pathways. The up-regulation of the primary calcium entry pathway in activated T cells, the store-operated calcium entry, and calcium elevations in response to T-cell receptor ligation were impaired in KD T cells. TRPM7 protein levels were increased in both WT and KD mouse T cells upon activation. Additionally, KD mice exhibited splenomegaly and increased extramedullary hematopoiesis, along with a modest pre-activation of T cells. The present work provides insights into the physiological role of TRPM7 kinase in regulating its channel activity and immune cell function.
Page Count
156
Department or Program
Biomedical Sciences
Year Degree Awarded
2018
Copyright
Copyright 2018, all rights reserved. My ETD will be available under the "Fair Use" terms of copyright law.
