Department of Pharmacology and Toxicology, and Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama.
Department of Pharmacology and Toxicology, and Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama
Drug Metab Dispos. 2018 Jan;46(1):41-45. doi: 10.1124/dmd.117.077560. Epub 2017 Nov 6.
Sulfotransferase 4A1 (SULT4A1) belongs to the cytosolic sulfotransferase (SULT) superfamily of enzymes that catalyze sulfonation reactions with a variety of endogenous and exogenous substrates. Of the SULTs, SULT4A1 was shown to have the highest sequence homology between vertebrate species, yet no known function or enzymatic activity has been identified for this orphan SULT. To better understand SULT4A1 function in mammalian brain, two mutant SULT4A1 mouse strains were generated utilizing clustered regulatory interspaced short palindromic repeats (CRISPR)-content-addressable storage (Cas) 9 technology. The first strain possessed a 28-base pair (bp) deletion (Δ28) in exon 1 that resulted in a frameshift mutation with premature termination. The second strain possessed a 12-bp in-frame deletion (Δ12) immediately preceding an active site histidine common to the SULT family. Homozygous pups of both strains present with severe and progressive neurologic symptoms, including tremor, absence seizures, abnormal gait, ataxia, decreased weight gain compared with littermates, and death around postnatal days 21-25. SULT4A1 immunostaining was decreased in brains of heterozygous pups and not detectable in homozygous pups of both SULT4A1 mutants. SULT4A1 localization in subcellular fractions of mouse brain showed SULT4A1 associated with mitochondrial, cytosolic, and microsomal fractions, a novel localization pattern for SULTs. Finally, primary cortical neurons derived from embryonic (E15) CD-1 mice expressed high levels of SULT4A1 throughout the cell except in nuclei. Taken together, SULT4A1 appears to be an essential neuronal protein required for normal brain function, at least in mammals. Mouse models will be valuable in future studies to investigate the regulation and functions of SULT4A1 in the mammalian brain.
磺基转移酶 4A1（SULT4A1）属于细胞溶质磺基转移酶（SULT）超家族的酶，可催化各种内源性和外源性底物的磺化反应。在 SULT 中，SULT4A1 在脊椎动物物种之间具有最高的序列同源性，但尚未确定该孤儿 SULT 的已知功能或酶活性。为了更好地了解 SULT4A1 在哺乳动物大脑中的功能，利用成簇规则间隔短回文重复（CRISPR）-内容可寻址存储（Cas）9 技术生成了两种突变的 SULT4A1 小鼠品系。第一株在exon 1 中具有 28 个碱基对（bp）的缺失（Δ28），导致移码突变和过早终止。第二株在 SULT 家族共有的活性位点组氨酸之前有 12 个碱基对的框内缺失（Δ12）。两种品系的纯合幼鼠均表现出严重且进行性的神经症状，包括震颤、失神发作、异常步态、共济失调、与同窝仔相比体重增加减少，并且在出生后第 21-25 天死亡。两种 SULT4A1 突变体的杂合幼鼠的 SULT4A1 免疫染色减少，而纯合幼鼠则无法检测到。SULT4A1 在小鼠大脑亚细胞部分中的定位显示 SULT4A1 与线粒体、细胞质和微粒体部分相关联，这是 SULTs 的一种新的定位模式。最后，源自胚胎（E15）CD-1 小鼠的原代皮质神经元在整个细胞中表达高水平的 SULT4A1，除了核外。总之，SULT4A1 似乎是一种必需的神经元蛋白，对于正常的大脑功能是必需的，至少在哺乳动物中是如此。小鼠模型将在未来的研究中具有重要价值，以研究 SULT4A1 在哺乳动物大脑中的调节和功能。
