SNU-Harvard Neurovascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
Int J Oncol. 2015 Jan;46(1):99-106. doi: 10.3892/ijo.2014.2708. Epub 2014 Oct 17.
ARD1 is an acetyltransferase with several variants derived from alternative splicing. Among ARD1 variants, mouse ARD1(225) (mARD1(225)), mouse ARD1(235) (mARD1(235)), and human ARD1(235) (hARD1(235)) have been the most extensively characterized and are known to have different biological functions. In the present study, we demonstrated that mARD1(225), mARD1(235), and hARD1(235) have conserved autoacetylation activities, and that they selectively regulate distinct roles of ARD1 variants in tumorigenesis. Using purified recombinants for ARD1 variants, we found that mARD1(225), mARD1(235), and hARD1(235) undergo similar autoacetylation with the target site conserved at the Lys136 residue. Moreover, functional investigations revealed that the role of mARD1(225) autoacetylation is completely distinguishable from that of mARD1(235) and hARD1(235). Under hypoxic conditions, mARD1(225) autoacetylation inhibited tumor angiogenesis by decreasing the stability of hypoxia-inducible factor-1α (HIF-1α). Autoacetylation stimulated the catalytic activity of mARD1(225) to acetylate Lys532 of the oxygen-dependent degradation (ODD) domain of HIF-1α, leading to the proteosomal degradation of HIF-1α. In contrast, autoacetylation of mARD1(235) and hARD1(235) contributed to cellular growth under normoxic conditions by increasing the expression of cyclin D1. Taken together, these data suggest that autoacetylation of ARD1 variants differentially regulates angiogenesis and cell proliferation in an isoform-specific manner.
ARD1 是一种具有多个变体的乙酰转移酶，这些变体来源于可变剪接。在 ARD1 变体中，小鼠 ARD1(225)(mARD1(225))、小鼠 ARD1(235)(mARD1(235))和人 ARD1(235)(hARD1(235))得到了最广泛的研究，其具有不同的生物学功能。在本研究中，我们证明 mARD1(225)、mARD1(235)和 hARD1(235)具有保守的自乙酰化活性，并且它们选择性地调节 ARD1 变体在肿瘤发生中的不同作用。使用纯化的 ARD1 变体重组体，我们发现 mARD1(225)、mARD1(235)和 hARD1(235)在赖氨酸 136 位的靶位上发生相似的自乙酰化。此外，功能研究表明 mARD1(225)自乙酰化的作用与 mARD1(235)和 hARD1(235)的作用完全不同。在低氧条件下，mARD1(225)的自乙酰化通过降低缺氧诱导因子-1α(HIF-1α)的稳定性来抑制肿瘤血管生成。自乙酰化刺激 mARD1(225)的催化活性，使其乙酰化 HIF-1α 的氧依赖性降解(ODD)结构域的赖氨酸 532，导致 HIF-1α 的蛋白酶体降解。相比之下，mARD1(235)和 hARD1(235)的自乙酰化在常氧条件下通过增加细胞周期蛋白 D1 的表达来促进细胞生长。总之，这些数据表明 ARD1 变体的自乙酰化以异构体特异性的方式差异调节血管生成和细胞增殖。
