[Distribution characteristic of NDRG2 expression in human fetal tissues.]

NDRG2, one of the new N-Myc downstream-regulated gene (NDRG) gene families, is believed to be involved in cell growth event. However, the exact function is still unknown. Identification of the tissue or cell types expressing this gene in vivo will provide clues in clarifying its physiological roles. Using RT-PCR and Western blot, we analyzed the expression level of NDRG2 mRNA and protein in human fetal tissues from different gestational ages. The anti-NDRG2 monoclonal antibody, which has been proved to react specifically with NDRG2 protein, was further used to analyze the cellular location of NDRG2 protein in various human fetal tissues by immunohistochemistry. We found that NDRG2 expression was developmentally dynamic, being generally lower in the early stages of development and markedly increasing during the later stages. NDRG2 mRNA and protein distribution were generally consistent in heart and lung. One of the differences was that NDRG2 protein appeared later than mRNA in kidney. Another unmatched expression was found in liver. NDRG2 mRNA appeared later than protein in liver. In human fetal tissues at sixteen and twenty-eight weeks of gestation, NDRG2 protein immunoreactions could be seen in epithelium of small intestine, epithelium of large intestine, superficial layer of epidermis, whisker follicles, epithelium of small bronchus, hepatocytes, cardiac myocytes, thymus corpuscles and epithelium of renal tubule, and the immunoreactions in those tissues from twenty-eight weeks of gestation was stronger than that from sixteen weeks of gestation. In the present study, we demonstrate the expression pattern and cellular location of NDRG2 protein in a large set of human fetal tissues. This is the first demonstration of NDRG2 protein expression in human fetal tissues. Taken together, the results suggest that NDRG2 protein found in a variety of tissues is not a tissue-specific protein, and may play important roles in histogenesis and organogenesis.