PURPOSE To investigate the structural remodeling in gap junctions associated with cholesterol redistribution during fiber cell maturation in the adult chicken lens. We also evaluated the hypothesis that the cleavage of the COOH-terminus of chick Cx50 (formerly Cx45.6) during fiber cell maturation would affect the gap junction remodeling. METHODS Freeze-fracture TEM and filipin cytochemistry w...

Opening of connexin hemichannels in the plasma membrane is highly regulated. Generally, depolarization and reduced extracellular Ca2+ promote hemichannel opening. Here we show that hemichannels formed of Cx50, a principal lens connexin, exhibit a novel form of regulation characterized by extraordinary sensitivity to extracellular monovalent cations. Replacement of extracellular Na+ with K+, whi...

PURPOSE Gap junctions between epithelial cells are essential for normal lens growth. In mice, knockout of Cx50 or targeted replacement of Cx50 with Cx46 (knockin) caused smaller lenses because of decreased epithelial cell proliferation. However, it remains unclear whether Cx50 functionally contributes to lens epithelial coupling during maximal proliferation on postnatal day 2 (P2) and P3. To de...

Folliculostellate cell gap junctions establish a network for the transmission of information within the anterior pituitary. Connexins make up gap junction channels. Changes in connexin (Cx) turnover modify gap junction-mediated intercellular communication. We have reported that cytokines and hormones influence Cx43 turnover and coupling in folliculostellate cells and in the folliculostellate ce...

PURPOSE Based on the knowledge that limbal epithelial stem cells (SCs) do not express keratin-3 (K3), connexin (Cx)43, and Cx50, a study was conducted to investigate amniotic membrane (AM) culturing conditions that promote limbal SC expansion. METHODS Human limbal epithelium was expanded on intact and epithelially denuded AM, with or without a 3T3 feeder layer, and subsequently transplanted t...

PURPOSE To determine the roles of intercellular communication in embryonic eye growth and development, mice with a targeted deletion of the Cx43 gene were examined, and mice without both Cx43 and Cx50 were generated and analyzed. METHODS Embryonic eyes and lenses from wild-type mice, or mice deficient in Cx43, Cx50, or both Cx43 and Cx50 were collected and analyzed structurally by light and e...

Gap junctions are multimeric membrane protein channels that connect the cytoplasm of one cell to another. Much information about connexins regards electrophysiology and channel function but relatively little information is known about non-channel functions of connexins. Lens connexins, Cx43, Cx46 and Cx50, have been extensively studied for their role in lens homeostasis. Connexins allow the mov...

The lens is proposed to have an internal microcirculation system consisting of continuously circulating ionic fluxes that play an essential role in maintaining lens transparency. One of the key components of this system is the sodium leak conductance. Here we investigate the contribution of Cx46 hemichannels to the basal membrane permeability of peripheral fiber cells isolated from transgenic m...

Connexin43 (Cx43) is widely expressed in many different tissues of the human body. In cells of some organs, Cx43 is co-expressed with other connexins (Cx), including Cx46 and Cx50 in lens, Cx40 in atrium, Purkinje fibers, and the blood vessel wall, Cx45 in heart, and Cx37 in the ovary. Interactions with the co-expressed connexins may have profound functional implications. The abilities of Cx37,...

The connexin (Cx) 50, E48K, mutation is associated with a human dominant congenital cataract; however, the underlying molecular mechanism has not been characterized. The glutamate (E) residue at position 48 is highly conserved across animal species and types of connexins. When expressed in paired Xenopus oocytes, human (h) and chicken (ch) Cx50 E48K mutants showed no electrical coupling. In add...