Department of Molecular, Cellular, and Developmental Biology, Yale University, Yale Science Building, 260 Whitney Avenue, P.O. Box 208103, New Haven, Connecticut 06520-8103, United States.
Department of Pharmacology, Yale University, New Haven, Connecticut 06511, United States.
ACS Chem Biol. 2021 Dec 17;16(12):2808-2815. doi: 10.1021/acschembio.1c00693. Epub 2021 Nov 15.
Protein phosphorylation, which regulates many critical aspects of cell biology, is dynamically governed by kinases and phosphatases. Many diseases are associated with dysregulated hyperphosphorylation of critical proteins, such as retinoblastoma protein in cancer. Although kinase inhibitors have been widely applied in the clinic, growing evidence of off-target effects and increasing drug resistance prompts the need to develop a new generation of drugs. Here, we propose a proof-of-concept study of phosphorylation targeting chimeras (PhosTACs). Similar to PROTACs in their ability to induce ternary complexes, PhosTACs focus on recruiting a Ser/Thr phosphatase to a phosphosubstrate to mediate its dephosphorylation. However, distinct from PROTACs, PhosTACs can uniquely provide target gain-of-function opportunities to manipulate protein activity. In this study, we applied a chemical biology approach to evaluate the feasibility of PhosTACs by recruiting the scaffold and catalytic subunits of the PP2A holoenzyme to protein substrates such as PDCD4 and FOXO3a for targeted protein dephosphorylation. For FOXO3a, this dephosphorylation resulted in the transcriptional activation of a FOXO3a-responsive reporter gene.
蛋白质磷酸化调节细胞生物学的许多关键方面，其活性受到激酶和磷酸酶的动态调控。许多疾病都与关键蛋白的异常过度磷酸化有关，例如癌症中的视网膜母细胞瘤蛋白。尽管激酶抑制剂已广泛应用于临床，但越来越多的证据表明其存在脱靶效应和药物耐药性增加，这促使人们需要开发新一代药物。在这里，我们提出了磷酸化靶向嵌合体（PhosTACs）的概念验证研究。PhosTACs 类似于 PROTACs，能够诱导三元复合物形成，将丝氨酸/苏氨酸磷酸酶募集到磷酸化底物上，介导其去磷酸化。然而，与 PROTACs 不同的是，PhosTACs 可以独特地提供靶蛋白获得功能的机会，从而操纵蛋白活性。在这项研究中，我们应用化学生物学方法来评估 PhosTACs 的可行性，方法是将 PP2A 全酶的支架和催化亚基招募到 PDCD4 和 FOXO3a 等蛋白底物上，以实现靶向蛋白去磷酸化。对于 FOXO3a，这种去磷酸化导致 FOXO3a 反应性报告基因的转录激活。
