OCM基因敲除HEK293细胞

In cochlear outer hair cells (OHCs), a network of Ca channels, pumps and Ca-binding proteins (CaBPs) regulates the localization, spread, and magnitude of free Ca ions. During early postnatal development, OHCs express three prominent mobile EF-hand CaBPs: oncomodulin (OCM), α-parvalbumin (APV) and sorcin. We have previously shown that deletion of Ocm (Ocm) gives rise to progressive cochlear dysfunction in young adult mice. Here, we show that changes in Ca signaling begin early in postnatal development of Ocm mice. While mutant OHCs exhibit normal electrophysiological profiles compared to controls, their intracellular Ca signaling is altered. The onset of OCM expression at postnatal day 3 (P3) causes a developmental change in KCl-induced Ca transients in OHCs and leads to slower KCl-induced Ca transients than those elicited in cells from Ocm littermates. We compared OCM buffering kinetics with other CaBPs in animal models and cultured cells. In a double knockout of Ocm and Apv (Ocm;Apv), mutant OHCs show even faster Ca kinetics, suggesting that APV may also contribute to early postnatal Ca signaling. In transfected HEK293T cells, OCM slows Ca kinetics more so than either APV or sorcin. We conclude that OCM controls the intracellular Ca environment by lowering the amount of freely available [Ca] in OHCs and transfected HEK293T cells. We propose that OCM plays an important role in shaping the development of early OHC Ca signals through its inimitable Ca buffering capacity.