Due to its unique structure and function, lens metabolism and ionic homeostasis depend absolutely on the lens fibers remaining interconnected to the surface epithelial cells by gap junctional communication pathways. Ionic homeostasis is essential in order to avoid cataract: precipitation of the high concentration of soluble proteins in the lens fiber cytoplasms. The long-term objectives of this proposal are to experimentally demonstrate the function of intercellular communication via gap junctions in lens development and homeostasis. Experiments are outlined which are designed carry out specific blocks of connexin functions in the lens. A Cx43 knockout mouse is now available commercially. These animals die at birth of cardiac defects thus living long enough to permit a study of the developmental and homeostatic sequellae of a knockout of Cx43, which is expressed first in normal lens development, and which persists in the mature lens in both epithelial cells and differentiating fibers. To block the function of other lens connexins, trans-dominant negative constructs which interfere with connexin function will be expressed in the mouse as transgenes driven by the alphaA-crystallin promoter, to target expression to the lens. In the chick, active trans-dominant negative constructs will be introduced into the developing lens by retroviral infection, using the replication- competent RCAS-A avian virus. In a second specific aim, phosphorylation sites on connexins will be mapped by conventional peptide mapping and sequencing. Key phosphorylated serine and threonine residues identified by this mapping will be mutated and epitope tagged. These connexin mutants will be introduced into lens cells in culture by transfection and into whole lenses using the RCAS retrovirus. The ability of the mutated connexins to assemble into channels, to be transported to the plasma membrane and to target to gap junctions will be followed by immunohistochemistry in both the cultures and in developing lenses. Transfection of these mutant connexins into the communication-negative Neuro2A neuroblastoma cell line will permit the study of changes in single channel conductance, voltage gating, and pH sensitivity resulting from the loss of specific phosphorylated residues.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY002430-21
Application #
2668366
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1978-03-01
Project End
2001-02-28
Budget Start
1998-03-01
Budget End
1999-02-28
Support Year
21
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Harvard University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Chai, Zhifang; Goodenough, Daniel A; Paul, David L (2011) Cx50 requires an intact PDZ-binding motif and ZO-1 for the formation of functional intercellular channels. Mol Biol Cell 22:4503-12
Magnotti, Laura M; Goodenough, Daniel A; Paul, David L (2011) Deletion of oligodendrocyte Cx32 and astrocyte Cx43 causes white matter vacuolation, astrocyte loss and early mortality. Glia 59:1064-74
Magnotti, Laura M; Goodenough, Daniel A; Paul, David L (2011) Functional heterotypic interactions between astrocyte and oligodendrocyte connexins. Glia 59:26-34
Hou, Jianghui; Goodenough, Daniel A (2010) Claudin-16 and claudin-19 function in the thick ascending limb. Curr Opin Nephrol Hypertens 19:483-8
Hou, Jianghui; Renigunta, Aparna; Gomes, Antonio S et al. (2009) Claudin-16 and claudin-19 interaction is required for their assembly into tight junctions and for renal reabsorption of magnesium. Proc Natl Acad Sci U S A 106:15350-5
Goodenough, Daniel A; Paul, David L (2009) Gap junctions. Cold Spring Harb Perspect Biol 1:a002576
Calera, Mónica R; Wang, Zhao; Sanchez-Olea, Roberto et al. (2009) Depression of intraocular pressure following inactivation of connexin43 in the nonpigmented epithelium of the ciliary body. Invest Ophthalmol Vis Sci 50:2185-93
Himmerkus, Nina; Shan, Qixian; Goerke, Boeren et al. (2008) Salt and acid-base metabolism in claudin-16 knockdown mice: impact for the pathophysiology of FHHNC patients. Am J Physiol Renal Physiol 295:F1641-7
Hou, Jianghui; Renigunta, Aparna; Konrad, Martin et al. (2008) Claudin-16 and claudin-19 interact and form a cation-selective tight junction complex. J Clin Invest 118:619-28
Calera, Monica R; Topley, Heather L; Liao, Yongbo et al. (2006) Connexin43 is required for production of the aqueous humor in the murine eye. J Cell Sci 119:4510-9

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