The oncoprotein LMO3 interacts with calcium- and integrin-binding protein CIB

The protein LMO3 belongs to the LIM only (LMO) group of transcriptional regulators, which act as molecular adaptors for protein–protein interactions. However, little is known about its interactive proteins and functions. Evaluating LMO3 in a yeast two-hybrid screen, we identified the calcium- and integrin-binding protein CIB as an LMO3-binding protein, which binds via the second LIM domain (LIM2) of LMO3. Cotransfection of LMO3 and CIB resulted in a shift in LMO3 protein from the nucleus to the cytoplasm. In functional assays, LMO3 induced C8 astrocyte proliferation was suppressed by the overexpression of CIB. This study demonstrates one function for LMO3 in C8 cells and suggests that one role of the CIB/LMO3 complex is to inhibit cell proliferation.