CaaX-motif-adjacent residues influence G protein gamma (Gγ) prenylation under suboptimal conditions.
CaaX-motif-adjacent residues influence G protein gamma (Gγ) prenylation under suboptimal conditions.
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DOI：
10.1016/j.jbc.2023.105269
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发表时间：
2023-11
期刊：
影响因子：
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通讯作者：
Karunarathne A
中科院分区：
文献类型：
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作者：
Tennakoon M;Thotamune W;Payton JL;Karunarathne A
预基化是一种不可逆的翻译后修饰，支持参与各种细胞过程的蛋白质之间的膜相互作用，包括迁移、增殖和生存。苯丙基化的失调会导致多种疾病，包括癌症、血管和神经退行性疾病。异戊二烯转移酶在异戊二烯基化过程中通过硫醚键将类异戊二烯类脂连接到蛋白质上。他汀类药物抑制脂质合成途径是控制高脂血症的一种治疗方法。基于我们先前的发现，他汀类药物以一种亚型依赖的方式抑制G蛋白γ(Gγ)的膜结合，我们研究了这种差异抑制的分子推理。我们检测了在氟伐他汀和异丙烯基转移酶抑制剂作用下的细胞中羧基末端(Ct)突变的G-γ的预烯基化，并用活细胞共聚焦成像技术监测了荧光标记的G-γ亚单位及其突变体的亚细胞定位。利用Ct残基的可逆光遗传去掩蔽-掩蔽来探讨它们对蛋白质的预烯基化和膜相互作用的贡献。我们的发现表明，特定的Ct残基调节Gγ多肽的膜相互作用，他汀类药物的敏感性，以及预烯基化的程度。我们的结果还表明，Ct上的几个疏水和带电残基是蛋白质预烯基化能力的关键决定因素，特别是在次优条件下。考虑到不同Gγ亚型在细胞和组织中的特异性表达，我们的发现表明了一种合理的机制，允许他汀类药物根据Gγ亚型的组成而不同地干扰细胞中的异源三聚体G蛋白信号。我们的结果也可能为他汀类药物作为RAS癌基因抑制剂的再利用以及在癌症治疗中使用异丙烯基转移酶抑制剂的失败提供分子推理。
Prenylation is an irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including migration, proliferation, and survival. Dysregulation of prenylation contributes to multiple disorders, including cancers and vascular and neurodegenerative diseases. Prenyltransferases tether isoprenoid lipids to proteins via a thioether linkage during prenylation. Pharmacological inhibition of the lipid synthesis pathway by statins is a therapeutic approach to control hyperlipidemia. Building on our previous finding that statins inhibit membrane association of G protein γ (Gγ) in a subtype-dependent manner, we investigated the molecular reasoning for this differential inhibition. We examined the prenylation of carboxy-terminus (Ct) mutated Gγ in cells exposed to Fluvastatin and prenyl transferase inhibitors and monitored the subcellular localization of fluorescently tagged Gγ subunits and their mutants using live-cell confocal imaging. Reversible optogenetic unmasking-masking of Ct residues was used to probe their contribution to prenylation and membrane interactions of the prenylated proteins. Our findings suggest that specific Ct residues regulate membrane interactions of the Gγ polypeptide, statin sensitivity, and extent of prenylation. Our results also show a few hydrophobic and charged residues at the Ct are crucial determinants of a protein’s prenylation ability, especially under suboptimal conditions. Given the cell and tissue-specific expression of different Gγ subtypes, our findings indicate a plausible mechanism allowing for statins to differentially perturb heterotrimeric G protein signaling in cells depending on their Gγ-subtype composition. Our results may also provide molecular reasoning for repurposing statins as Ras oncogene inhibitors and the failure of using prenyltransferase inhibitors in cancer treatment.