(The) roles of anoctamin chloride channels regulating embryonic neurogenesis

Abstract

The embryonic neurogenesis which new neurons are generated in the embryonic brain is critical for the development of the central nervous system. Abnormal neurogenesis often results in some fatal defects in the brain development as well as psychological disorders. As neurons become mature, the decrease of intracellular chloride ion concentration in the embryonic neurons determines transmembrane potential of neuronal membrane, which regulates actions of GABAergic transmission in the early brain development. Although the concentration of intracellular chloride ion is actively determined in the embryonic neurodevelopment by chloride transporters, NKCC1 and KCC2, it remains clearly unknown about how Cl - permeable chloride channels are involved in the embryonic CNS development. The anoctamin family (ANOs) is endogenous calcium activated chloride channels with various physiological functions. With the fact that Ca 2+ signals, widely known as a second messenger, generated during the embryonic neurogenesis mediate calcium activated chloride channels, we therefore investigated whether anoctamins are required for the embryonic neurogenesis. Using real time quantitative-PCR technique, we determined the level of mRNAs of various anoctamin channels as embryonic neural ii stem/progenitor cells increase the size of neurosphere. As a result, we found that mRNA levels of ANO3, ANO6, ANO8, and ANO10 were increased as the size of neurospheres enlarged. Especially, ANO8 was extensively increased by about 1000- fold. In addition, we identified ANO8 expression pattern in the developing brain. Moreover, we performed the knock down assay of ANO8 for proliferation assay and migration assay. Then, we determined that ANO8 had influence on cellular migration, not on proliferation. Taken together, these results suggest that ANO3, ANO6, ANO8, and ANO10 play important roles in embryonic neural stem/progenitor cells. In particular, ANO8 have been strongly connected to embryonic neurogenesis. This study provides insights into molecular mechanisms underlying chloride channels are involved in the embryonic neurodevelopment.