My laboratory focuses on the molecular processes underlying excitation-contraction coupling, particularly in smooth muscle cells. Current studies seek to understand the role of specific sarcoplasmic reticular calcium release channels and sarcolemmal ion channels in cellular excitation and relaxation. Techniques used to study these processes include gene targeting, identification of novel genes through genomics screens, patch clamp measurements of ion channel function, confocal and wide-field imaging, and protein biochemistry. A major goal of the laboratory is to identify genes encoding channel proteins and relating signaling molecules involved in muscle biology and to determine the extent to which these genes are altered in specific disease processes.
Projects in the laboratory include the study of the role of the ryanodine receptor complex in smooth muscle contraction. Our work and that of others has identified a type of calcium-induced calcium release that occurs during smooth muscle contraction. This process was previously thought to occur only in striated muscle, but takes a unique form in smooth muscle. To study this process and its physiological importance we have created mice deficient in ryanodine receptor complex genes in smooth muscle, including those encoding ryanodine receptors and FK506 binding proteins. Related projects include to the regulation of the function of the ryanodine receptor complex and the role of this complex in other tissues.
An additional effort in the laboratory is to combine genetics, molecular design, and optical technologies to advance the understanding of physiological processes. An example of this effort can be seen in the figure depicting the first Ca2+ signaling mouse, which we created in collaboration with the laboratory of Dr. Junichi Nakai. This mouse expresses a protein in smooth muscle tissues that fluoresces when Ca2+ increases during cellular processes. Several variants of Ca2+ signaling mice and mice that sense other critical signals are being created in the laboratory.
A second major project in the lab involves the use of gene trap methods to identify novel genes involved in muscle biology and the creation of transgenic mice to facilitate determination of their functions. As part of this process, techniques have been developed to efficiently trap genes in embryonic stem cells and to subsequently inactivate the trapped genes.
A third project is the investigation of the role of specific sarcolemmal ion channels in muscle excitation, rythmicity, and relaxation using conditional gene targeting methods in mice. Determination of gene function is through phenotype analysis in physiological assays as well as by cellular and molecular determination of function using patch-clamp and imaging methods.