Human connexin43 gene locus, GJA1, sublocalized to band 6q21-->q23.2.

Gap junctions permit transfer of small molecules directly between cells. Several laboratories have mapped the human gap junction protein subunit, connexin43 (locus designation, GJA1), to overlapping regions of chromosome 6, localizing GJA1 to 6q14-->q24. We have sublocalized human GJA1 to a very small region. 6q21-->q23.2, using a human x rodent somatic cell hybrid mapping panel and a rat connexin43 cDNA probe.

Refined localization of human connexin32 gene locus, GJB1, to Xq13.1.

Connexins are the peptide subunits of gap junctions that interconnect cells to allow the direct, intercellular transfer of small molecules. Recently, the human connexin32 gene (locus designation GJB1) has been regionally mapped by three other laboratories to Xp11-q13, Xcen-q22, and Xp11-q22. The smallest region of overlap from these studies is Xcen-q13. By using a series of somatic cell hybrid mapping panels and a rat connexin32 cDNA probe, we have localized the human GJB1 locus to a much smaller region in proximal Xq13.1, in interval 8, as described by Lafrenière et al. (8).

Inhibition of metabolic coupling by metals.

Several metals were evaluated in cell cultures for their ability to inhibit metabolic coupling, the intercellular transfer of low-molecular-weight metabolites by directly connecting gap junctions. To monitor inhibition of metabolic coupling, wild-type Chinese hamster V79 cells proficient in metabolism of 6-thioguanine (6-TG) were cocultured with mutant V79 cells unable to metabolize 6-TG to its toxic metabolite (6-TG-resistant cells). In the presence of 6-TG, inhibition of metabolic coupling by the metals was manifested as increased recovery of 6-TG-resistant cells compared to recovery in untreated cocultures. The toxic metal compounds, arsenic(V) acid, mercury(II) chloride, lead(II) acetate, and nickel(II) chloride, significantly (p less than .05) increased recovery of 6-TG-resistant cells at concentrations that did not alter cell survival. However, because the increased recovery observed with nickel showed no concentration dependence, its importance may be negligible. Cadmium chloride increased 6-TG-resistant cell recovery only at a toxic concentration, and zinc sulfate failed to increase recovery. These data demonstrate that some metal compounds inhibit metabolic coupling, and suggest that inhibition of junctional communication should be further evaluated as a potential mechanism of toxicity of some metals.

Cultured myometrial cells establish communicating gap junctions.

Myometrial cells were isolated and cultured from term rat uterus. The myometrial origin of the cultures was verified by antibody staining of cellular desmin and alpha-smooth muscle actin. The presence of functional gap junctions was indicated by transfer of radiolabeled nucleotide and microinjected Lucifer yellow dye. The cultured cells expressed mRNA recognized by a connexin43 gap junction cDNA probe. To our knowledge, this is the first report that isolated myometrial cells form gap junctions in culture.

Interruption of cell-cell communication in Chinese hamster V79 cells by various alkyl glycol ethers: implications for teratogenicity.

Intercellular communication most likely plays a significant coordinating role in morphogenesis. Blockage of a specific type of intercellular communication, that mediated by gap junctions, has been proposed as a mechanism of action of some teratogens. Several glycol ethers have recently been shown to be teratogenic in laboratory animals. Because these compounds are negative in genotoxic assays, it is suggested that they may act by nongenetic, perhaps membrane-mediated mechanisms. In the present study several structurally related alkyl glycol ethers were examined for their ability to block junction-mediated intercellular communication. Interruption of intercellular communication was measured in vitro by an assay that depends on the transfer of metabolites via gap junctions, i.e., metabolic cooperation. All compounds tested--ethylene glycol (EG), ethylene glycol monomethyl ether (EGME), ethylene glycol monoethyl ether (EGEE), ethylene glycol monopropyl ether (EGPE), and ethylene glycol monobutyl ether (EGBE)--were able to block metabolic cooperation in vitro. The potencies of the compounds were inversely related to the length of the aliphatic chain, the dose required for maximum blockage increasing as the aliphatic chain shortened. Some differences in the maximum amount of blockage were detected, but these were not consistent and hence were not considered significant. Cytotoxicity, as measured by cell survival, was also related to the structure of the compound, generally increasing with increased length of the aliphatic chain. There were structurally related differences in the concentration ranges over which the compounds were effective.(ABSTRACT TRUNCATED AT 250 WORDS)