Ahn Hyoungjoon, Yu Jeongmin, Ryu Kwangmin, Ryu Jaeseung, Kim Sera, Park Jae Yeong, Kim Ji Kwang, Jung Inhong, An Haejin, Hong Sehoon, Kim Eunha, Park Kihyun, Ahn Myunghwan, Min Sunwoo, Jung Inkyung, Lee Daeyoup, Lee Thomas, Byun Youngjoo, Song Ji-Joon, Kim Jaehoon, Cho Won-Ki, Lee Gwangrog, Kim Seyun
Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
College of Pharmacy, Korea University, 2511 Sejong-ro, Sejong 30019, Republic of Korea.
Nucleic Acids Res. 2025 Jan 7;53(1). doi: 10.1093/nar/gkae1281.
Serum response factor (SRF) is a master transcription factor that regulates immediate early genes and cytoskeletal remodeling genes. Despite its importance, the mechanisms through which SRF stably associates with its cognate promoter remain unknown. Our biochemical and protein-induced fluorescence enhancement analyses showed that the binding of SRF to serum response element was significantly increased by inositol polyphosphate multikinase (IPMK), an SRF cofactor. Moreover, real-time tracking of SRF loci in live cell nuclei demonstrated that the chromatin residence time of SRF was reduced by IPMK depletion in fibroblasts. Conversely, elevated IPMK levels extended the SRF-chromatin association. We identified that IPMK binds to the intrinsically disordered region of SRF, which is required for the IPMK-induced stable interaction of SRF with DNA. IPMK-mediated conformational changes in SRF were observed by single-molecule fluorescence resonance energy transfer assays. Therefore, our findings demonstrate that IPMK is a critical factor for promoting high-affinity SRF-chromatin association and provide insights into the mechanisms of SRF-dependent transcription control via chaperone-like activity.
血清反应因子（SRF）是一种主要的转录因子，可调节即早基因和细胞骨架重塑基因。尽管其很重要，但SRF与其同源启动子稳定结合的机制仍不清楚。我们的生化分析和蛋白质诱导荧光增强分析表明，肌醇多磷酸多激酶（IPMK）作为一种SRF辅因子，可显著增强SRF与血清反应元件的结合。此外，对活细胞核中SRF位点的实时追踪表明，在成纤维细胞中，IPMK的缺失会缩短SRF在染色质上的停留时间。相反，IPMK水平升高会延长SRF与染色质的结合。我们发现IPMK与SRF的内在无序区域结合，这是IPMK诱导SRF与DNA稳定相互作用所必需的。通过单分子荧光共振能量转移分析观察到了IPMK介导的SRF构象变化。因此，我们的研究结果表明，IPMK是促进SRF与染色质高亲和力结合的关键因子，并通过类似分子伴侣的活性为SRF依赖性转录控制机制提供了见解。
