Maret Alexander, Bourdeau Isabelle, Ding Changlin, Kadkol Shrihari S, Westra William H, Levine Michael A
Division of Pediatric Endocrinology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
J Clin Endocrinol Metab. 2004 Jan;89(1):8-12. doi: 10.1210/jc.2003-030733.
GCMA and GCMB are related transcription factors that are critically important for embryological development of the placenta and parathyroid glands, respectively. Mice in which parathyroid glands have been surgically removed or fail to develop due to genetic loss of GCMB show continued production of PTH from a subset of thymic cells that express GCMA. In this study we examined whether human thymus produces PTH and/or GCMA and whether intrathymic PTH-secreting adenomas express GCMA or GCMB to determine the embryological origin of the secretory cells. By contrast to mouse thymus, analysis of 22 samples of human thymus tissue by RT-PCR and/or immunohistochemistry failed to demonstrate the expression of either PTH or GCMA. RT-PCR analysis of 16 intrathymic adenomas from patients with surgically cured primary hyperparathyroidism showed that these tumors expressed PTH and GCMB and not GCMA. We conclude that the normal human thymus does not express GCMA or PTH, and therefore, in contrast to the mouse, the human thymus is not a source of PTH production. Finally, intrathymic PTH-secreting adenomas express the parathyroid-specific GCMB gene, which suggests that these tumors were derived from parathyroid cells that migrated errantly during embryogenesis.
GCMA和GCMB是相关的转录因子，分别对胎盘和甲状旁腺的胚胎发育至关重要。因GCMB基因缺失而导致甲状旁腺被手术切除或未能发育的小鼠，其胸腺细胞亚群中持续产生甲状旁腺激素（PTH），这些胸腺细胞表达GCMA。在本研究中，我们检测了人类胸腺是否产生PTH和/或GCMA，以及胸腺内分泌PTH的腺瘤是否表达GCMA或GCMB，以确定分泌细胞的胚胎起源。与小鼠胸腺不同，通过逆转录聚合酶链反应（RT-PCR）和/或免疫组织化学对22份人类胸腺组织样本进行分析，未能证实PTH或GCMA的表达。对16例手术治愈的原发性甲状旁腺功能亢进患者的胸腺内腺瘤进行RT-PCR分析显示，这些肿瘤表达PTH和GCMB，而不表达GCMA。我们得出结论，正常人类胸腺不表达GCMA或PTH，因此，与小鼠不同，人类胸腺不是PTH产生的来源。最后，胸腺内分泌PTH的腺瘤表达甲状旁腺特异性的GCMB基因，这表明这些肿瘤来源于胚胎发生过程中错误迁移的甲状旁腺细胞。
