Human variant sex hormone-binding globulin (SHBG) with an additional carbohydrate chain has a reduced clearance rate in rabbit
Human variant sex hormone-binding globulin (SHBG) with an additional carbohydrate chain has a reduced clearance rate in rabbit
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DOI：
10.1210/jc.83.1.235
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发表时间：
1998-01-01
影响因子：
5.8
通讯作者：
Brébant, C
中科院分区：
文献类型：
--
作者：
Cousin, P;Déchaud, H;Brébant, C
性激素结合球蛋白（SHBG）是人类性类固醇激素的特异性血浆转运蛋白。SHBG血浆浓度在个体之间存在相当大的差异，无论性别，体重或甲状腺状态如何。在本工作中，使用兔模型研究了碳水化合物链对人SHBG（hSHBG）半衰期的影响。最近已经鉴定了一种变体hSHBG，其在编码氨基酸取代（Asp 327 Asn）的外显子8（GAC -> AAC）中具有点突变，该氨基酸取代引入了额外的N-糖基化共有位点。这种突变抑制了限制性内切酶Bbs-I的识别位点，从而允许开发一种简单的限制性片段长度多态性（RFLP）筛选程序。在我们的内分泌诊所咨询的患者人群（272名女性和49名男性）中，48名患者（41名女性和7名男性）为hSHBG等位基因变异杂合子，3名患者（2名女性和1名男性）为纯合子。在该人群中，总变异等位基因频率为0.083。通过RFLP确定的hSHBG基因型在所有情况下都与通过Western印迹分析确定的hSHBG迁移曲线所确定的表型相对应，研究了这种额外的糖基化位点对变体hSHBG生物半衰期的影响。从携带三种hSHBG基因型之一的患者血清中提取SHBG，纯化并用生物素标记，然后注射到兔子体内，正如我们最近对兔子SHBG的描述。从兔血清样品中捕获生物素化的hSHBG，置于涂有抗hSHBG抗体的试管中，并用链霉亲和素-碱性磷酸酶-二氧杂环丁烷（AMPPD）系统通过光度法检测。结果表明，半衰期值显著高于纯合子变异血清中SHBG纯化组与对照组比较差异有显著性（P < 0.05）（t 1/2 β = 51.43 +/- 1.15和63.63 +/- 3.92 h，对于男性和女性受试者SHBG分别）比从杂合变体血清中纯化的SHBG（t1/2 β = 40.19 +/- 0.12 h）或野生型（t1/2 β = 38.18 +/- 7.22 h）。这种变异等位基因的低频率意味着需要进一步的研究来确定它是否与较高的血清SHBG浓度相关。
Sex hormone-binding globulin (SHBG) is the specific plasma transport protein for sex steroid hormones in humans. Considerable variation in SHBG plasma concentration exists between individuals, irrespective of gender, body weight, or thyroid status. In the present work, the influence of carbohydrate chains on the half-life of human SHBG (hSHBG) was investigated using a rabbit model. A variant hSHBG, with a point mutation in exon 8 (GAC --> AAC) encoding an amino acid substitution (Asp327Asn), which introduces an additional consensus site for N-glycosylation, has recently been identified. This mutation suppresses a recognition site for the restriction enzyme Bbs-I, allowing the development of a simple restriction-fragments length polymorphism (RFLP) screening procedure. In a population of patients (272 female and 49 male) consulting in our Endocrinology Clinic, 48 patients (41 female and 7 male) were heterozygous for the variant hSHBG allele and 3 (2 female and 1 male) were homozygous. In this population, the total variant allele frequency was 0.083. The hSHBG genotype, as determined by RFLP, corresponded in all cases to the phenotype as determined by the migration profile of hSHBG by Western blot analysis.The influence of such an additional glycosylation site on the biological half-life of variant hSHBG was investigated. SHBG from serum of patients carrying one of the three hSHBG genotypes was purified and labeled with biotin, then injected into rabbits, as we have recently described for rabbit SHBG. Biotinylated hSHBG was captured from rabbit serum samples on tubes coated with an anti-hSHBG antibody and detected by luminometry with the streptavidine-alkaline phosphatase-dioxetane (AMPPD) system. The results showed that the half-life Value was significantly higher (P < 0.05) for SHBG purified from homozygous variant serum (t 1/2 beta = 51.43 +/- 1.15 and 63.63 +/- 3.92 h, for male and a female subjects SHBG respectively) than for SHBG purified from heterozygous variant serum (t 1/2 beta = 40.19 +/- 0.12 h) or wild-type (t 1/2 beta = 38.18 +/- 7.22 h).This study demonstrated that an additional carbohydrate chain on hSHBG decreases the clearance rate of this protein. The low frequency of this variant allele means that further study will be required to determine whether it is associated with higher serum SHBG concentration.