Laminin‐5 alters intercellular communication in ciliated tracheal epithelial cells via connexin rearrangment

The extracellular matrix protein laminin‐5 (Ln5) can be produced by bronchial epithelial cells in response to wounding. As cell‐cell communication is vital in wound repair, we tested if Ln5 altered intercellular communication in ciliated rabbit tracheal epithelial cells (RTEC). To test initially for functional gap junctions, we microinjected RTEC plated on either collagen (Col) matrix or Col/Ln5 matrix with the negatively charged dyes Lucifer Yellow (LY) and Alexa 350 (A350). Compared to RTEC plated on Col, RTEC plated on Col/Ln5 displayed a significant increase in dye transfer, with A350 having a larger incidence of coupling than LY. In contrast, microinjection of the positively charged dye NBD‐TMA revealed a low incidence of coupling in RTEC plated on Col that was further reduced in RTEC plated on Col/Ln5. We next tested whether RTEC plated on Col/Ln5 could respond to localized mechanical stimulation by propagating intercellular Ca 2+ waves via gap junctions as previously detailed in RTEC plated on Col. Although we observed Ca 2+ waves in these cells, the mechanism of propagation was via a purinergic signaling pathway and independent of gap junctions. Using RT‐PCR and Western blot, no change in connexin mRNA or protein expression were observed between RTEC plated on Col or Col/Ln5 matrices. However, using immunocytochemistry, we observed a Ln5‐dependent reorganization of Cx26, Cx43 and Cx46 proteins. We hypothesize that the Ln5‐dependent alterations in dye transfer and Ca 2+ communication are due to connexin protein reorganization in RTEC.