Inhibition of cell cycle progression by the alternatively spliced integrin beta 1C

Integrins regulate cell growth, differentiation, and behavior in many systems. Integrin beta 1C (beta 1S) is an alternatively spliced variant of integrin beta 1 with a specific cytoplasmic domain and is expressed in several human tissues. Human beta 1c transiently expressed in mouse 10T1/2 fibroblasts showed a diffuse pattern of cell surface staining, whereas beta1 localized to focal adhesions. Moderate concentrations of beta 1C had no effect on actin stress fibers or focal adhesions, but markedly inhibited DNA synthesis. Inhibition by beta 1C mapped to the late G1 phase of the cell cycle, near the G1-S boundary. Thus, alternative splicing of beta1 results in transmission of distinct signals that may regulate growth in vivo.