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

Centrins are small calcium-binding proteins found in a variety of cell type s, often in association with microtubule-organizing centers. Here we presen t results regarding the expression of centrins during the in vitro differen tiation of human tracheal epithelial cells. When grown at an air-liquid int erface, these cells differentiate into mucus-secreting cells or undergo cil iogenesis. In immunofluorescence and immunoelectron microscopy experiments, an anti-centrin antibody stained exclusively the basal bodies of the cilia ted 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 gr owth and differentiation of human tracheal epithelial cells. Centrin-1 is n ever transcribed. Centrin-2 mRNA is present at all times, and its concentra tion increases when ciliogenesis occurs. Centrin-3 mRNA is found at a const ant level throughout the entire process. This differential regulation sugge sts that centrins are not interchangeable but instead have unique functions .