Abstract
We have previously reported that a macrophage/microglia-specific calcium binding protein Iba1 is involved in advanced motility and phagocytic activity of these cells, and is concerned specifically with signaling of Rac small G protein among members of Rho family GTPases. We report herein identification and characterization of an Iba1 homologous molecule, Iba2, with 63% amino acid identity with Iba1. In contrast to the restricted expression of Iba1 in macrophages/microglia, Iba2 was predominantly expressed in cells in the neural lineage. Iba2 was intensely expressed in the developing brain, of which the expression was localized in nestin-positive cells within the ventricular and subventricular zones, i. e. neural precursor cells. Even in the adult brain, Iba2 was expressed in neural precursor cells in the rostral migratory stream. Furthermore, when Iba2 was expressed simultaneously with dominant active RacV12 in NIH3T3 cells, Iba2 translocated together with F-actin into membrane ruffles induced by RacV12 and the expression of Iba2 potentiated promotion of the membrane ruffling. These results suggest that Iba2 should, as a counterpart of Iba1, participate in a migratory phenotype of neural precursor cells. [Jpn J Physiol 55 Suppl:S78 (2005)]
