| 研究実績の概要 |
BAT is an energy consuming tissue, studied for obesity therapy. We observed an inverse relationship between BAT activity and cir-miR-122 concentrations in humans. We aim to establish an association of BAT activity with circulating miR-122 levels, source and target tissue of miR-122 during BAT activation, and effects of increased levels of BAT activation-induced miR-122 on NEFA and glucose metabolism.
WT and Ucp1KO mice were divided into groups: cold (10±2°C) or room temperature (23±2°C) for cold-induced BAT activation, and injected with a beta-3-adrenergic receptor agonist, CL316,243 (CL) or saline for drug-induced BAT activation and sacrificed 4 hours after treatment.
MiR-122 is mainly liver-secreted. Liver and plasma concentrations of miR-122 in cold-exposed WT mice have an inverse relationship. Both BAT activations show different changes in hepatic pre-miR-122 concentrations in both genotypes, which may have contributed to varied trends in cir-miR-122 concentrations in control and treatment groups. Both BAT activations decreased miR-122 in BAT of WT mice. Ucp1KO mice had lowered hepatic miR-122 compared to WT mice, further decreasing after cold exposure. Cir-miR-122 of cold-exposed Ucp1KO mice increased. WT plasma glucose ranged of 241-288 mg/dL and increased post-CL treatment. WT plasma NEFA concentration was increased 8.5 times after CL-injection. Ucp1KO basal glucose levels were lower than WT and increased after cold exposure. Unique control of miR-122 levels seems to be substrate-dependent Ucp1-independent phenomena, but direct experimental proof is still needed.
|
| 今後の研究の推進方策 |
To test the relationship of fatty acid concentrations, miR-122 levels and BAT activation in mice. WT male C57BL/6J mice will be used and housed under the standard conditions and given food and water ad libitum. Treatment groups will be (1) Fasted mice: food will be withdrawn for a minimum of 16 h prior to sacrifice; (2) Cold-exposed mice: placed in 10±2 °C for 1 hour and (3) Beta-3-adrenergic agonist injected mice: CL316,243 (CL; 0.1 mg/kg, IP). All mice, except the cold-exposed group, will be placed in room temperature (23±2 °C) environment 1 hour prior to sampling. To test the relationship of obesity, fatty acid concentrations and miR-122 levels relationship in mice. Mice will be given laboratory chow ad libitum for 10 weeks, then be fed with a high-fat diet (HFD). After, mice will be fed with a HFD for 18-20 weeks. Treatment groups will be: (1) Fasted for 24 hours and (2) Fasted and refed: food will be withdrawn for 24 h from mice, and then they will be fed the same high-fat diet for 1 h prior to sampling of blood and organs. Control mice will be given laboratory chow diet ad libitum, until 12 weeks of age. Water will be given ad libitum throughout the study period. All mice will be placed in room temperature (23±2 °C) environment 1 hour prior to sampling. Analysis of samples: Blood, exosomes extracted from blood and organ (liver, BAT and skeletal muscles) miR-122 expression will also be measured by qPCR. Exosome amounts in the blood sample will be estimated. Hepatic pre-miR-122 expression and blood glucose and NEFA concentrations will be also measured.
|
