Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA.
Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA.
Genes Dev. 2018 Apr 1;32(7-8):555-567. doi: 10.1101/gad.309773.117. Epub 2018 Apr 13.
Although peroxisome proliferator-activated receptor-γ (PPARγ) coactivator 1α (PGC-1α) is a well-established transcriptional coactivator for the metabolic adaptation of mammalian cells to diverse physiological stresses, the molecular mechanism by which it functions is incompletely understood. Here we used in vitro binding assays, X-ray crystallography, and immunoprecipitations of mouse myoblast cell lysates to define a previously unknown cap-binding protein 80 (CBP80)-binding motif (CBM) in the C terminus of PGC-1α. We show that the CBM, which consists of a nine-amino-acid α helix, is critical for the association of PGC-1α with CBP80 at the 5' cap of target transcripts. Results from RNA sequencing demonstrate that the PGC-1α CBM promotes RNA synthesis from promyogenic genes. Our findings reveal a new conduit between DNA-associated and RNA-associated proteins that functions in a cap-binding protein surveillance mechanism, without which efficient differentiation of myoblasts to myotubes fails to occur.
虽然过氧化物酶体增殖物激活受体γ（PPARγ）共激活因子 1α（PGC-1α）是哺乳动物细胞对各种生理应激进行代谢适应的一种成熟的转录共激活因子，但它的作用机制尚不完全清楚。在这里，我们使用体外结合测定、X 射线晶体学和小鼠成肌细胞裂解物的免疫沉淀，来定义 PGC-1α C 端中以前未知的帽结合蛋白 80（CBP80）结合基序（CBM）。我们表明，该基序由一个九氨基酸的α螺旋组成，对于 PGC-1α 与靶转录物 5'帽上的 CBP80 的结合至关重要。来自 RNA 测序的结果表明，PGC-1α CBM 促进了成肌基因的 RNA 合成。我们的研究结果揭示了一种在 DNA 相关蛋白和 RNA 相关蛋白之间起作用的新途径，它在帽结合蛋白监测机制中发挥作用，如果没有这种机制，成肌细胞向肌管的有效分化就无法发生。
