Taylor E W
Computational Center for Molecular Structure and Design, University of Georgia, Athens 30602-2352, USA.
Biol Trace Elem Res. 1995 Aug-Sep;49(2-3):85-95. doi: 10.1007/BF02788958.
Selenium deficiency can lead to impaired immune function and reduced T-cell counts, as well as various specific disorders. Significantly, in ARC and AIDS patients, a progressive decline in plasma Se, paralleling T-cell loss, has been widely documented. Since evidence now suggests that there is an extremely high turnover of CD4+ T-cells in AIDS patients, with billions of new cells lost and replaced daily, any exceptional requirement for Se in lymphocytes could contribute to this progressive Se depletion. Thus, it may be significant that, overlapping the known genes in the +1 reading frame, the mRNAs of several T-cell associated genes (CD4, CD8, HLA-DR p33) have open reading frames (ORFs) with as many as 10 in-frame UGA codons (CD4, p33), a clustering that is highly improbable by chance alone, and reminiscent of selenoprotein P, the predominant plasma form of Se. The presence of these ORFs, along with potential stem-loop RNA structures displaying consensus selenocysteine insertion sequences, AUG(N)mAAA(N)nUGR, suggests that these mRNAs may encode selenoproteins, in addition to the known T-cell glycoproteins. If so, the roles of Se in the immune system may be more diverse than previously suspected.
硒缺乏会导致免疫功能受损、T细胞计数减少以及各种特定疾病。值得注意的是，在艾滋病相关综合征（ARC）和艾滋病患者中，血浆硒水平随着T细胞数量的减少而逐渐下降，这一点已有广泛记录。由于现在有证据表明艾滋病患者体内CD4 + T细胞的更新速度极快，每天有数十亿新细胞丢失并被替换，淋巴细胞对硒的任何特殊需求都可能导致这种硒的逐渐消耗。因此，可能具有重要意义的是，在 +1 阅读框中与已知基因重叠的几个T细胞相关基因（CD4、CD8、HLA - DR p33）的mRNA具有开放阅读框（ORF），其中含有多达10个框内UGA密码子（CD4、p33），这种聚集仅靠偶然是极不可能出现的，并且让人联想到硒蛋白P，即血浆中硒的主要形式。这些开放阅读框的存在，以及显示出共有硒代半胱氨酸插入序列AUG(N)mAAA(N)nUGR的潜在茎环RNA结构，表明这些mRNA除了编码已知的T细胞糖蛋白外，还可能编码硒蛋白。如果是这样，硒在免疫系统中的作用可能比之前怀疑的更加多样。
