Chromogranin A (CHGA), a protein participating in the biogenesis of dense core secretory granules in various neuroendocrine tissues, plays a critical role in the release of hormones/peptides and the pathogenesis of pheochromocytoma. However, little is known about the developmental origin of CHGA-expressing cells during embryogenesis. Here, we report the structural characterization and spatio-temporal expression pattern of zebrafish (Danio rerio) ortholog of mammalian CHGA. The earliest expression of chga transcripts was observed at 16 h post fertilization in the developing cranial ganglia as six distinct cellular masses arranged bilaterally as strings of beads in the dorsal root ganglia (DRG) precursors along the dorsal trunk. With development advancing, the chga transcripts were expressed abundantly in diencephalon, mesencephalon, and rhombencephalon as well as in the DRG. Interestingly, double in situ hybridization assay of chga with genes expressed in pronephros (Wilms' tumor suppressor 1, wt1), adrenal cortex (side-chain cleavage enzyme, scc), and sympathoadrenal neuron/chromaffin cell (dopamine-β-hydroxylase, dbh), respectively, showed that the chga-expressing cells are spatially separated from wt1-, scc-, and dbh-positive cell populations during early embryonic development. The pronephros region does not express chga even up to 7 days post fertilization, while chga positive-staining cells bind in the brain and DRG, indicating that chga may play an important role in nervous system development during the early embryonic stages.
Jing Xie, Wei-Qing Wang, Ting-Xi Liu, Min Deng and Guang Ning
Lei Ye, Xiaoying Li, Xiangyin Kong, Weiqing Wang, Yufang Bi, Landian Hu, Bin Cui, Xi Li and Guang Ning
The ectopic ACTH syndrome is caused by abnormal expression of the POMC gene product arising from non-pituitary tumors in response to the ectopic activation of the pituitary-specific promoter of this gene. It has been proved that methylation of the CpG island in the promoter region is associated with silencing of some genes. Using bisulphite sequencing, we identified hypermethylation in the 5′ promoter region of the POMC gene in three normal thymuses and one large cell lung cancer, and hypomethylation in five thymic carcinoid tumors resected from patients with ectopic ACTH syndrome. The region undergoing hypermethylation was narrowed to coordinates −417 to −260 of the POMC promoter. Furthermore, we observed that the levels of POMC expression correlated with the methylation density at −417 to −260 bp across the E2 transcription factor binding region of the POMC promoter. It is concluded that hypomethylation of the POMC promoter in thymic carcinoids correlates with POMC overexpression and the ectopic ACTH syndrome.
Qinglei Yin, Liyun Shen, Yicheng Qi, Dalong Song, Lei Ye, Ying Peng, Yanqiu Wang, Zhou Jin, Guang Ning, Weiqing Wang, Dongping Lin and Shu Wang
SIRT1, a class III histone/protein deacetylase (HDAC), has been associated with autoimmune diseases. There is a paucity of data about the role of SIRT1 in Graves’ disease. The aim of this study was to investigate the role of SIRT1 in the pathogenesis of GD. Here, we showed that SIRT1 expression and activity were significantly decreased in GD patients compared with healthy controls. The NF-κB pathway was activated in the peripheral blood of GD patients. The reduced SIRT1 levels correlated strongly with clinical parameters. In euthyroid patients, SIRT1 expression was markedly upregulated and NF-κB downstream target gene expression was significantly reduced. SIRT1 inhibited the NF-κB pathway activity by deacetylating P65. These results demonstrate that reduced SIRT1 expression and activity contribute to the activation of the NF-κB pathway and may be involved in the pathogenesis of GD.