IRCCS SDN, Naples, Italy.
Institute of Biostructures and Bioimaging, CNR, Naples 80134, Italy.
Int J Biol Macromol. 2018 Aug;115:469-475. doi: 10.1016/j.ijbiomac.2018.04.078. Epub 2018 Apr 14.
KCTD15 is a member of the K+ Channel Tetramerization Domain family, implicated in crucial physio-pathological processes. Recent evidences suggest that KCTD15 is an obesity-linked protein in humans and its Drosophila homologue is involved in food uptake. KCTD15 molecular mechanism in these processes is still unknown. To fill this gap, KCTD15 was biophysically characterized showing a folded, pentameric region endowed with a remarkable thermal stability. Notably, the C-terminal domain significantly contributes to the stabilization of the BTB N-terminal domain. The availability of large amount of stable recombinant protein also made possible a functional proteomic approach in 3T3-L1 cells to search for novel KCTD15 interactors. These investigations led to the discovery that GRP78 is a KCTD15 partner in all the adipogenesis phases. Our data clearly prove the physical interaction of the two proteins and also indicate that GRP78 plays an active role in the stabilization of KCTD15. Furthermore, the presence in Drosophila of a GRP78 homologue corroborates the physiological role played by the complex KCTD15-GRP78 in the adipogenesis process and indicates that it is evolutionarily conserved. Present results also suggest that KCTD15 may be a new target for obesity control.
KCTD15 是 K+通道四聚化结构域家族的成员，参与许多重要的生理病理过程。最近的证据表明，KCTD15 是人类肥胖相关蛋白，其果蝇同源物参与食物摄取。但 KCTD15 在这些过程中的分子机制尚不清楚。为了填补这一空白，我们对 KCTD15 进行了生物物理特性分析，结果显示其为折叠的五聚体区域，具有显著的热稳定性。值得注意的是，C 端结构域对 BTB N 端结构域的稳定有重要贡献。大量稳定重组蛋白的获得也使得能够在 3T3-L1 细胞中进行功能性蛋白质组学方法研究，以寻找新的 KCTD15 相互作用蛋白。这些研究发现，GRP78 是 KCTD15 在所有脂肪生成阶段的伴侣。我们的数据清楚地证明了这两种蛋白的物理相互作用，还表明 GRP78 在 KCTD15 的稳定中发挥积极作用。此外，果蝇中存在 GRP78 同源物，这进一步证明了 KCTD15-GRP78 复合物在脂肪生成过程中的生理作用，表明其在进化上是保守的。目前的结果还表明，KCTD15 可能是肥胖控制的新靶点。
