Differential regulation of centrin genes during ciliogenesis in human tracheal epithelial cells.

Centrins are small calcium-binding proteins found in a variety of cell types, often in association with microtubule-organizing centers. Here we present results regarding the expression of centrins during the in vitro differentiation of human tracheal epithelial cells. When grown at an air-liquid interface, these cells differentiate into mucus-secreting cells or undergo ciliogenesis. In immunofluorescence and immunoelectron microscopy experiments, an anti-centrin antibody stained exclusively the basal bodies of the ciliated cells. There was no staining over the axonemes or the striated rootlets. Northern blots and RT-PCR analysis of the three known human centrin genes showed that these genes have distinct patterns of expression during the growth and differentiation of human tracheal epithelial cells. Centrin-1 is never transcribed. Centrin-2 mRNA is present at all times, and its concentration increases when ciliogenesis occurs. Centrin-3 mRNA is found at a constant level throughout the entire process. This differential regulation suggests that centrins are not interchangeable but instead have unique functions.