title: MafA is a Key Molecule in Glucose and Energy Balance in the Central Nervous System and Peripheral Organs.
abstract: MafA is a strong transactivator of insulin in pancreatic β cells. Elucidating the profile of MafA action in organs other than the pancreas is essential. We established an mRNA interference technique that modifies the level of target mRNAs in mice in vivo. After rapidly injecting MafA-siRNA, the resulting changes in the gene profile were analyzed using a microarray system. Significant suppression of the MafA mRNA levels was observed in the pancreas, liver, adipose tissue, and brain of siRNA-injected mice. As we reported previously, the down-regulation of insulin mRNA and adipocytokines was observed in the pancreas, and MafA siRNA caused alterations in the expressions of genes related to lipid metabolism and cell growth in the liver, and the attenuation of cell differentiation in cultured adipocytes. In addition to the effects on these organs, MafA expression was immunohistochemically detected in the brain in our preliminary data, and the expression level in siRNA-treated mice was significantly suppressed. The expressions of the affected genes were distinct, including growth hormone, vasopressin, hypocretin, and pro-melanin-concentrating hormone, were almost completely down-regulated (to ~1/100). These results suggested that MafA is likely involved in the regulation of hormonal systems related to glucose metabolism, and MafA is likely positioned near the beginning of the cascade or may influence the expressions of the above-mentioned genes in coordination with other factors in brain tissue. Taken together, the findings in this study suggested that MafA functions as a transcription factor with distinct activities in each organ and is cross-linked in several organs.
authors.affiliation: Institute of Geriatrics, Tokyo Women's Medical University, Japan;
authors.forename: Mariko
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Ken
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yasuda
authors.forename: Mikiko
authors.initials: M
authors.lastname: Fujita
authors.forename: Akira
authors.initials: A
authors.lastname: Takinishi
authors.forename: Maiko
authors.initials: M
authors.lastname: Furukawa
authors.forename: Kosaku
authors.initials: K
authors.lastname: Nitta
authors.forename: Atsushi
authors.initials: A
authors.lastname: Maeda
keywords: MafA; central nervous system; microarray; siRNA; transcriptional factor