Biophysical characterization of gap-junction channels in HeLa cells

Abstract

Abstract. HeLa cells seem not to be junctionally coupled when probed with techniques such as Lucifer yellow spreading and/or ionic coupling measured with three inserted microelectrodes. When investigated with double whole-cell patch-clamp measurements, HeLa cells in monolayer cultures were electrically coupled in 39% of the cases with very low transjunctional conductances (average one to five open channels). These gapjunction channels had a single-channel conductance ~ = 26 _+ 6 pS and were voltage-gated with an equivalent gating charge z = 3.1 + 1.5 for a voltage of half-maximal inactivation Uo = 49 + 10 mV. The voltage-dependent component represents only 31 __ 8% of the total junctional conductance. The voltage-insensitive conductance is characterized by a residual open probability po(~) = 0.34 _+ 0.12, which corresponds to a ratio G~n/ Gmax = 0.50 __+ 0.12. Dissociation of monolayer cells into cell pairs yielded about 58% coupled cell pairs with no notably altered single-channel properties.

Connexin Type and Fluorescent Protein Fusion Tag Determine Structural Stability of Gap Junction Plaques

“…We replicated these findings (Fig. 3E) in connexin-deficient N2A (transformed neural origin mouse cells) and RINm cells (Table 3) in order to rule out a cell line-specific effect and because HeLa cells sometimes express a very small number of Cx45 channels endogenously, resulting in channel activity detectible only by dualcell patch clamp electrophysiological recordings (31). These core results are summarized in Table 1.…”

Long-term connexin-mediated bystander effect in highly tumorigenic human cells in vivo in herpes simplex virus thymidine kinase/ganciclovir gene therapy

“…This may be due to a residual GJIC capacity in Cx43 − cells, as has been previously observed. 24 RT-PCR analyses did not reveal any HSVtk mRNA in any of the tumors we tested, suggesting that the GCV treatment was efficient even if the bystander effect was not complete (Figure 4). When these tumors were cultured and exposed to GCV, they were not killed, confirming the lack of HSVtk gene.…”

Cone Photoreceptors in Bass Retina Use Two Connexins to Mediate Electrical Coupling

“…1). Nontransfected HeLa cells always showed a low level of Neurobiotin (Vector Laboratories, Burlingame, CA) tracer coupling and a very low level of Lucifer yellow coupling, reflecting the expression of small amounts of endogenous connexin presumed to be Cx45 (Eckert et al, 1993). Transfection with Cx35 eliminated Lucifer yellow coupling and led to moderate increases in Neurobiotin tracer coupling similar to that seen with mouse Cx36 (Teubner et al, 2000).…”