Department of Medicine, Operative Unit of Andrology and Medicine of Human Reproduction, University of Padova, Padova, Italy.
Department of Surgical, Oncological and Gastroenterological Sciences, University of Padova, Padova, Italy.
J Clin Endocrinol Metab. 2018 May 1;103(5):2033-2041. doi: 10.1210/jc.2017-02762.
The regulation of bone mass by the testis is a well-recognized mechanism, but the role of Leydig-specific marker insulin-like 3 peptide (INSL3) on the most abundant bone cell population, osteocytes, is unknown. In this study, we aimed to investigate the relationship between INSL3 and sclerostin, an osteocyte-specific protein that negatively regulates bone formation.
Serum sclerostin and INSL3 levels were evaluated in Klinefelter syndrome (KS) and healthy controls. In vitro effect of INSL3 on sclerostin production was evaluated in human cultured osteocytes.
A total of 103 KS patients and 60 age- and sex-matched controls were recruited.
Serum sclerostin and INSL3 levels were assessed by enzyme-linked immunosorbent assay. Osteocytes were isolated by fluorescence-assisted cell sorting. Sclerostin expression was evaluated by western blot, immunofluorescence, and reverse transcription polymerase chain reaction. Measurement of bone mineral density was done by dual-energy X-ray absorptiometry at lumbar spine (L1-L4) and femoral neck.
Sclerostin levels were significantly increased in KS subjects, and negatively correlated with INSL3 levels in both cohorts and with bone mineral density in the KS group. Stimulation of cultured osteocytes with INSL3 at 10-7 M significantly decreased both sclerostin messenger RNA and protein expression.
We report a negative association between the testicular hormone INSL3 and the osteocytic negative regulator of bone formation, sclerostin. We further explored this association in vitro and showed that INSL3 was able to reduce sclerostin expression. These results add further knowledge on the emerging role of sclerostin as a therapeutic target for osteoporosis treatment.
睾丸对骨量的调节是一种公认的机制，但莱迪希细胞特异性标志物胰岛素样 3 肽（INSL3）对骨细胞中最丰富的群体——骨细胞的作用尚不清楚。在这项研究中，我们旨在研究 INSL3 与骨形成负调控蛋白骨硬化蛋白之间的关系。
评估克氏综合征（KS）患者和健康对照者的血清骨硬化蛋白和 INSL3 水平。评估 INSL3 对人培养骨细胞中骨硬化蛋白产生的体外作用。
共纳入 103 例 KS 患者和 60 名年龄和性别匹配的对照者。
采用酶联免疫吸附试验检测血清骨硬化蛋白和 INSL3 水平。采用荧光激活细胞分选法分离骨细胞。采用 Western blot、免疫荧光和逆转录聚合酶链反应评估骨硬化蛋白的表达。采用双能 X 射线吸收法测量腰椎（L1-L4）和股骨颈的骨矿物质密度。
KS 患者的骨硬化蛋白水平显著升高，并且在两个队列中均与 INSL3 水平呈负相关，与 KS 组的骨矿物质密度呈负相关。10-7 M 的 INSL3 刺激培养的骨细胞可显著降低骨硬化蛋白信使 RNA 和蛋白表达。
我们报告了睾丸激素 INSL3 与成骨负调控因子骨硬化蛋白之间存在负相关。我们进一步在体外研究了这种相关性，并表明 INSL3 能够降低骨硬化蛋白的表达。这些结果进一步证明了骨硬化蛋白作为骨质疏松症治疗的治疗靶点的新兴作用。
