The Laird laboratory has been involved in basic cell biology studies related to connexin assembly and gap junction turnover since 1992. The importance of examining the mechanisms, events and pathways related to the life cycle of connexins is highlighted by the fact that connexins have a short half-life of 4 hours or less, strongly suggesting that the extent of gap junctional intercellular communication can be exquisitely regulated by channel formational and removal. To facilitate these studies, we have developed several strategies to examine connexin transport, assembly and degradation in living cells using a variety of fluorescent tags and time-lapse imaging techniques. These approaches allow for one, two or three fluorescently-tagged connexins or associated molecules to be simultaneously followed with a single cell or colony of cells.
We are also interested in pioneering new imaging processes that will allow quantitative analysis of connexin movements within cells. Together with molecular interventions using dominant-negative constructs and siRNA approaches, key transport or assembly specific molecules can be examined for their role in regulating the life cycle of connexins in normal, tumor and polarized cells. Functional cell-cell communication is routinely quantified by the microinjection or pre-loading of small fluorescent dyes that are capable of passing from one cell to another through gap junctions. Together these studies are designed to investigate the role connexin assembly and turnover play in regulating the levels of cell-cell communication in response to physiological stimuli.
D.W. Laird (2010) “The gap junction proteome and its relationship to disease” Trends in Cell Biology 20:92-101.
J. Simek, J. Churko, Q. Shao and D.W. Laird (2009) “Cx43 has distinct mobility within plasma- membrane domains, indicative of progressive formation of gap-junction plaques” Journal of Cell Science 122:554-562. Featured Article “In this Issue”
N. Sultana, K. Nag, K. Hoshijima, D.W. Laird A. Kawakami and S. Hirose (2008) “Zebrafish early cardiac connexin, Cx36.7/Ecx, regulates myofibril orientation and heart morphogenesis by establishing Nkx2.5 expression” Proceeding National Academy of Science 105:4763-4768.
S. Langlois, Q. Shao, and D.W. Laird (2008) “Caveolin-1 and -2 interact with Cx43 and modulate gap junctional intercellular communication in keratinocytes” Molecular Biology of the Cell 19: 912-928.
S. Langlois, A.C. Maher, J.L. Manias, Q. Shao, G.M. Kidder and D.W. Laird (2007) “Connexin levels regulate keratinocyte differentiation in the epidermis”Journal of Biological Chemistry 282: 30171-30180.