NDRG2 as a marker protein for brain astrocytes

The protein NDRG2 (N-myc downregulated gene 2) is expressed in astrocytes. We show here that NDRG2 is located in the cytosol of protoplasmic and fibrous astrocytes throughout the mammalian brain, including Bergmann glia as observed in mouse, rat, tree shrew, marmoset and human. NDRG2 immunoreactivity is detectable in the astrocytic cell bodies and excrescencies including fine distal processes. Glutamatergic and GABAergic nerve terminals are associated with NDRG2 immunopositive astrocytic processes. Müller glia in the retina displays no NDRG2 immunoreactivity. NDRG2 positive astrocytes are more abundant and more evenly distributed in the brain than GFAP (glial fibrillary acidic protein) immunoreactive cells. Some regions with very little GFAP such as the caudate nucleus show pronounced NDRG2 immunoreactivity. In white matter areas, NDRG2 is less strong than GFAP labeling. Most NDRG2 positive somata are immunoreactive for S100ß but not all S100ß cells express NDRG2. NDRG2 positive astrocytes do not express nestin and NG2 (chondroitin sulfate proteoglycan 4). The localization of NDRG2 overlaps only partially with that of aquaporin 4, the membrane-bound water channel that is concentrated in the astrocytic endfeet. Reactive astrocytes at a cortical lesion display very little NDRG2, which indicates that expression of the protein is reduced in reactive astrocytes. In conclusion, our data show that NDRG2 is a specific marker for a large population of mature, non-reactive brain astrocytes. Visualization of NDRG2 immunoreactive structures may serve as a reliable tool for quantitative studies on numbers of astrocytes in distinct brain regions and for high-resolution microscopy studies on distal astrocytic processes.     

NDRG2 is a new HIF-1 target gene necessary for hypoxia-induced apoptosis in A549 cells.

The NDRG2 gene belongs to a family of N-Myc downstream-regulated genes (NDRGs) and is expressed in many normal tissues. NDRG2 gene expression has been shown to be regulated in the stress response of certain cells. However, its function is not yet fully understood. Many studies have demonstrated that hypoxia, one of the stress responses, induced apoptosis in several cell types. In the current study, we investigated NDRG2 involvement in hypoxia response and found that NDRG2 expression was markedly up-regulated in several tumor cell lines exposed to hypoxic conditions or similar stresses at the mRNA and protein level. We also observed that the expression of NDRG2 was regulated by Hypoxia-inducible factor 1 (HIF-1) in tumor cells under hypoxia. Three hypoxia-responsive elements (HREs) in the NDRG2 promoter were identified. HRE1 could directly bind Hif-1 in vivo. Importantly, we found that silencing or enforcing the expression of NDRG2 could strongly inhibit or increase apoptosis. In addition, our data also showed that Ndrg2 was able to be translocated from the cytoplasm to the nucleus, and the segment from 101 to 178 amino acids of Ndrg2 is responsible for its translocation. Taken together, this study suggests that NDRG2 is a Hif-1 target gene and closely related with hypoxia-induced apoptosis in A549 cells.     

NDRG2 induced by oxidized LDL in macrophages antagonizes growth factor productions via selectively inhibiting ERK activation

During atherogenesis, macrophage foam cells produce prodigious growth factors, cytokines, and chemokines, which play the central roles in inflammatory process in atherosclerotic plaque formation. In the present study, we identified a new protein marker, N-Myc downstream-regulated protein 2 (NDRG2), which is significantly up-regulated in oxidized low density lipoprotein (oxLDL) treated macrophages and in human atherosclerotic plaques. Over-expression and siRNA knockdown studies showed that NDRG2 is a negative regulator of platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) productions in macrophages. Furthermore, we investigated the effects of NDRG2 on MAPK signal activation. Our results showed ERK1/2 activation, but not P38 or JNK1/2 activation, is responsible for regulation of NDRG2 on VEGF and PDGF productions. Consistent with the PDGF levels, the vascular smooth muscle cell (VSMC) proliferation was also regulated by the conditional medium of the oxLDL treated macrophages with NDRG2 knockdown or over-expression. Neutralizing anti-PDGF antibody can significantly inhibit the enhanced VSMC proliferation by macrophage medium with NDRG2 knockdown. Our present results demonstrate that NDRG2 participates in oxLDL-induced macrophage activation and modulates ERK1/2-dependent PDGF and VEGF production, which has potential application in atherogenesis.     

Upregulation of dihydropyrimidinase-related protein 2, spectrin alpha II chain, heat shock cognate protein 70 pseudogene 1 and tropomodulin 2 after focal cerebral ischemia in rats--a proteomics approach

In recent years, there are an increasing number of proteomics studies that investigated the alterations in the protein expression relevant to human diseases but none for stroke. We, therefore, attempted such a study in a paradigm of focal cerebral ischemia in rat. Rats were subjected to cerebral ischemia by unilateral occlusion of the middle cerebral artery. Global protein analysis was performed after 24h on the lesioned and sham-control cerebral cortex using two-dimensional gel electrophoresis. Protein spots with more than a 3-fold change in intensity were identified by mass spectrometry. Middle cerebral artery occlusion (MCAO) caused infarct volume of 18-22% predominantly in the cortex of the lesioned hemisphere. Two-dimensional gel electrophoresis resolved about 1500 protein spots of which only 12 were significantly upregulated by 3-46-fold. Three spots were identified to be dihydropyrimidinase-related protein 2 (DRP-2, also known as collapsin response mediator protein 2 (CRMP-2) or turned on after division, 64 kD protein (TOAD-64)). The spots varied in pI values only and this may reflect different phosphorylation status of the same protein. Two spots were identified as spectrin alpha II chain (rat fragment, also known as alpha-fodrin or non-erythroid alpha chain, SPNA-2); and one spot each for heat shock cognate protein 70 pseudogene 1 (HSC70-ps1, also known as heat shock protein 8 pseudogene 1), and tropomodulin 2 (Tmod2). The upregulation of protein expression was corroborated by observed upregulation of mRNA expression. The remaining five spots were not identified satisfactorily. As DRP-2, spectrin, and Tmod2 are involved in axonal and neurite growth as well as synaptic plasticity and maturation, the presently observed upregulation of the expression of these proteins may indicate active neuroregeneration and repair at 24h after the induction of cerebral ischemia.     

Novel PRMT5-mediated arginine methylations of HSP90A are essential for maintenance of HSP90A function in NDRG2low ATL and various cancer cells

N-myc downstream-regulated gene 2 (NDRG2) as a tumor suppressor is frequently downregulated in human T-lymphotropic retrovirus (HTLV-1)-infected adult T-cell leukemia (ATL) and variety of cancers, and negatively regulates PI3K signaling pathways through dephosphorylation of PTEN with protein phosphatase 2A (PP2A). We recently identified that protein arginine methyltransferase 5 (PRMT5) is one of novel NDRG2 binding proteins and the knockdown of PRMT5 induces cell apoptosis with degradation of several signaling molecules. To investigate how the apoptosis is induced by the knockdown PRMT5 expression, heat shock protein 90 alpha (HSP90A) was identified as a binding protein for NDRG2 or PRMT5 by immunoprecipitation-mass analysis. NDRG2/PP2A complex inhibited arginine methyltransferase activity of PRMT5 through dephosphorylation at Serine 335 (S335); however, in NDRG2^low ATL-related cells, highly phosphorylated PRMT5 at S335 was mainly localized in cytoplasm with binding to HSP90A, resulting in enhancing arginine-methylation at the middle domain (R345 and R386). Since knockdown of PRMT5 expression or forced expression of HSP90A with alanine replacement of R345 or R386 induced apoptosis with the degradation of client proteins in NDRG2^low ATL-related and other cancer cells, we here identified that the novel arginine methylations of HSP90A are essential for maintenance of its function in NDRG2^low ATL and other cancer cells.     

基于生物信息学的抑癌基因NDRG2相互作用蛋白预测及验证

NDRG2(N Myc downstream regulator gene 2)是NDRG 家族成员之一. 以往研究表明,该家族与细胞的增殖和分化有关. 而该分子参与的细胞信号通路及调节机制尚未阐明. 本研究利用保守蛋白间相互作用（interologs）的生物信息学方法预测NDRG2相互作用分子,并通过免疫共沉淀（Co-IP）及His pull-down蛋白体外结合实验方法对预测结果进行验证. 生物信息学软件预测和分析结果表明,细胞中存在多个可能与NDRG2发生相互作用分子.结合文献报道,从中选取了3个候选分子Gnb1、 Rgs16及 Rgs5进行分子生物学实验验证.Co-IP及His pull-down实验结果表明,3个候选分子中,Rgs5蛋白能够和NDRG2蛋白相互作用,而其它2个候选分子与NDRG2的相互作用未获得实验室方法的验证.研究结果表明,生物信息学分析与实验室验证相结合是一种高效省时的蛋白质相互作用研究策略.通过这种策略证实NDRG2可以与 Rgs5蛋白相互作用,为后续NDRG2功能的研究提供了有效的线索.     

Upregulation of dihydropyrimidinase-related protein 2, spectrin α II chain, heat shock cognate protein 70 pseudogene 1 and tropomodulin 2 after focal cerebral ischemia in rats—A proteomics approach

In recent years, there are an increasing number of proteomics studies that investigated the alterations in the protein expression relevant to human diseases but none for stroke. We, therefore, attempted such a study in a paradigm of focal cerebral ischemia in rat. Rats were subjected to cerebral ischemia by unilateral occlusion of the middle cerebral artery. Global protein analysis was performed after 24 h on the lesioned and sham-control cerebral cortex using two-dimensional gel electrophoresis. Protein spots with more than a 3-fold change in intensity were identified by mass spectrometry. Middle cerebral artery occlusion (MCAO) caused infarct volume of 18–22% predominantly in the cortex of the lesioned hemisphere. Two-dimensional gel electrophoresis resolved about 1500 protein spots of which only 12 were significantly upregulated by 3–46-fold. Three spots were identified to be dihydropyrimidinase-related protein 2 (DRP-2, also known as collapsin response mediator protein 2 (CRMP-2) or turned on after division, 64 kD protein (TOAD-64)). The spots varied in pI values only and this may reflect different phosphorylation status of the same protein. Two spots were identified as spectrin α II chain (rat fragment, also known as α-fodrin or non-erythroid α chain, SPNA-2); and one spot each for heat shock cognate protein 70 pseudogene 1 (HSC70-ps1, also known as heat shock protein 8 pseudogene 1), and tropomodulin 2 (Tmod2). The upregulation of protein expression was corroborated by observed upregulation of mRNA expression. The remaining five spots were not identified satisfactorily. As DRP-2, spectrin, and Tmod2 are involved in axonal and neurite growth as well as synaptic plasticity and maturation, the presently observed upregulation of the expression of these proteins may indicate active neuroregeneration and repair at 24 h after the induction of cerebral ischemia.     

Microarray profiling of HepG2 cells ectopically expressing NDRG2

Previous studies have demonstrated that N-Myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor that is downregulated in many human cancers and when overexpressed, can inhibit tumor growth and metastasis. However, its molecular function, its modulatory targets, and signaling pathways associated with it remain unclear. Here, in an effort to identify the genes modulated by NDRG2 expression, a microarray study was conducted to detect the expression profile of HepG2 cells overexpressing NDRG2 or LacZ. Gene Ontology (GO) biological process analysis revealed that genes related to G protein signaling pathway were upregulated. Five of them were selected and verified by real-time PCR. Gene sets related to M phase of cell cycle were downregulated. This was in agreement with cell cycle analysis. Signaling pathway analysis demonstrated apparent augmented hematopoietic cell lineage pathway and cell adhesion, but reduced glycosylphosphatidylinositol (GPI)-anchor biosynthesis, protein degradation and SNARE interactions. Furthermore, through motif analysis and experimental validation, we found that the p38 phosphorylation can be increased by NDRG2. Our research provides the molecular basis for understanding the role of NDRG2 in tumor cells and raises interesting questions about its mechanisms and potential use in cancer therapy.     

N-myc downstream-regulated gene 2 controls astrocyte morphology via Rho-GTPase signaling

Astrocyte undergoes morphology changes that are closely associated with the signaling communications at synapses. N-myc downstream-regulated gene 2 (NDRG2) is specifically expressed in astrocytes and is associated with several important astrocyte functions, but its potential role(s) relating to astrocyte morphological changes remain unknown. Here, primary astrocytes were prepared from neonatal Ndrg2^+/+ and Ndrg2^−/− pups, and the drug Y27632 was used to induce stellation. We then used a variety of methods to measure the levels of NDRG2, α-Actinin4, and glial fibrillary acidic protein (GFAP), and the activity of RhoA, Rac1, and Cdc42 in Y27632-treated astrocytes as well as in Ndrg2^+/+, Ndrg2^−/−, or Ndrg2^−/− + lentivirus (restore NDRG2 expression) astrocytes. We also conducted live-imaging and proteomics studies of the cultured astrocytes. We found that induction of astrocytes stellation (characterized by cytoplasmic retraction and process outgrowth) resulted in increased NDRG2 protein expression and Rac1 activity and in reduced α-Actinin4 protein expression and RhoA activity. Ndrg2 deletion induced astrocyte flattening, whereas the restoration of NDRG2 expression induced stellation. Ndrg2 deletion also significantly increased α-Actinin4 protein expression and RhoA activity yet reduced GFAP protein expression and Rac1 activity, and these trends were reversed by restoration of NDRG2 expression. Collectively, our results showed that Ndrg2 deletion promoted cell proliferation, interrupted stellation capability, and extensively altered the protein expression profiles of proteins that function in Rho-GTPase signaling. These findings suggest that NDRG2 functions to regulate astrocytes morphology via altering the accumulation of the Rho-GTPase signaling pathway components, thereby supporting that NDRG2 should be understood as a regulator of synaptic plasticity and thus neuronal communications.     

(NDRG2) stimulates amiloride-sensitive Na+ currents in Xenopus laevis oocytes and fisher rat thyroid cells

Regulation of the epithelial sodium channel (ENaC) is highly complex and may involve several aldosterone-induced regulatory proteins. The N-Myc downstream-regulated gene 2 (NDRG2) has been identified as an early aldosterone-induced gene. Therefore, we hypothesized that NDRG2 may affect ENaC function. To test this hypothesis we measured the amiloride-sensitive (2 microm) whole cell current (DeltaI(ami)) in Xenopus laevis oocytes expressing ENaC alone or co-expressing ENaC and NDRG2. Co-expression of NDRG2 significantly increased DeltaI(ami) in some, but not, all batches of oocytes tested. An inhibitory effect of NDRG2 was never observed. Using a chemiluminescence assay we demonstrated that the NDRG2-induced increase in ENaC currents was accompanied by a similar increase in channel surface expression. The stimulatory effect of NDRG2 was preserved in oocytes maintained in a low sodium bath solution to prevent sodium feedback inhibition. These findings suggest that the stimulatory effect of NDRG2 is independent of sodium feedback regulation. Furthermore, the stimulatory effect of NDRG2 on ENaC was at least in part additive to that of Sgk1. A short isoform of NDRG2 also stimulated DeltaI(ami). Overexpression of NDRG2 and ENaC in Fisher rat thyroid cells confirmed the stimulatory effect of NDRG2 on ENaC-mediated short-circuit current (I(SC-ami)). In addition, small interference RNA against NDRG2 largely reduced I(SC-ami) in Fisher rat thyroid cells. Our results indicate that NDRG2 is a likely candidate to contribute to aldosterone-mediated ENaC regulation.     

Proteomics identified nuclear N-myc downstream-regulated gene 1 as a prognostic tissue biomarker candidate in renal cell carcinoma

The aim of this study was to identify proteins with aberrant expression in clear cell renal cell carcinoma (ccRCC), and elucidate their clinical utilities. The protein expression profiles of primary ccRCC tumor tissues and neighboring non-tumor tissues were obtained from 9 patients by two-dimensional difference gel electrophoresis and mass spectrometry. Comparative analysis of 3771 protein spots led to the identification of 73 proteins that were expressed at aberrant levels in tumor tissues compared with non-tumor tissues. Among these 73 proteins, we further focused on N-myc downstream-regulated gene 1 protein (NDRG1). NDRG1 expression is regulated by members of myc family as well as by p53, HIF1A, and SGK1. The biological and clinical significance of NDRG1 is controversial for various malignancies and no detailed studies on NDRG1 have been reported in ccRCC until our study. For the 82 newly enrolled ccRCC patients, immunohistochemical analysis revealed a significant association between nuclear NDRG1 and favorable prognosis (p < 0.05). Multivariate analysis demonstrated the role of NDRG1 as an independent factor of progression-free survival (p = 0.01). Subsequent in vitro gene suppression assay demonstrated that NDRG1 silencing significantly enhanced cell proliferation and invasion of RCC cells. The cytotoxic effects of NDRG1 up-regulation induced by an iron chelator were also confirmed. These findings suggest that nuclear NDRG1 has tumor suppressive effects, and the NDRG1 expression may have clinical values in ccRCC. Nuclear NDRG1 may provide additional insights on molecular backgrounds of ccRCC progression, and contribute to the development of novel therapeutic strategy.     

NDRG2与GFAP在不同脑区星形胶质细胞的表达与分布

目的:观察NDRG2(N-myc下游调节基因2)与GFAP(胶质纤维酸性蛋白)在不同脑区星形胶质细胞的表达与分布。方法:利用免疫荧光NDRG2与GFAP双标技术以及Western Blot技术观察皮层、海马及纹状体等不同脑区星形胶质细胞NDRG2和GFAP的表达与分布。结果:免疫荧光结果显示NDRG2阳性细胞广泛而均匀地分布于不同脑区,并与GFAP存在较好的共定位;NDRG2与GFAP标记的星形胶质细胞形态不尽相同。Western Blot结果显示NDRG2在皮层中表达比海马和纹状体多,而GFAP在海马中表达比皮层和纹状体多。结论:NDRG2广泛表达于不同脑区星形胶质细胞,并于GFAP存在较好的共定位。     

Establishment of a two-dimensional electrophoresis map for Neospora caninum tachyzoites by proteomics

Expressed proteins and antigens from Neospora caninum tachyzoites were studied by two-dimensional gel electrophoresis and immunoblot analysis combined with matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Thirty-one spots corresponding to 20 different proteins were identified from N. caninum tachyzoites by peptide mass fingerprinting. Six proteins were identified from a N. caninum database (NTPase, 14-3-3 protein homologue, NcMIC1, NCDG1, NcGRA1 and NcGRA2), and 11 proteins were identified in closely related species using the T. gondii database (HSP70, HSP60, pyruvate kinase, tubulin alpha- and beta-chain, putative protein disulfide isomerase, enolase, actin, fructose-1,6-bisphosphatase, lactate dehydrogenase and glyceradehyde-3-phosphate dehydrogenase). One hundred and two antigen spots were observed using pH 4-7 IPG strips on immunoblot profiles. Among them, 17 spots corresponding to 11 antigenic proteins were identified from a N. caninum protein map. This study involved the construction of in-depth protein maps for N. caninum tachyzoites, which will be of value for studies of its pathogenesis, drug and vaccine development, and phylogenetic studies.     

NDRG2 通过调控CD24 影响肝癌细胞侵袭能力的研究

目的：阐明NDRG2（N-Myc downstream-regulated gene 2）在肝癌细胞中对CD24 的调控及其对乳腺癌细胞侵袭能力的影响。 方法：Western blot 检测低转移性的肝癌细胞Huh7、高转移性的肝癌细胞系MHCC97h 及正常人肝细胞系L-02 中NDRG2 和 CD24 的表达;通过腺病毒载体上调MHCC97h 细胞中NDRG2 的水平,或利用siRNA 下调Huh7 细胞中NDRG2 的表达,检测 CD24 的变化以及细胞侵袭能力的改变。结果：MHCC97h 细胞中NDRG2 基因和蛋白的表达水平低于Huh7 细胞,而CD24 的表达 水平高于Huh7 细胞;在MHCC97h 细胞中上调NDRG2 可以抑制CD24 的表达并抑制其侵袭能力,而在Huh7 细胞中下调 NDRG2 的表达可以提高CD24 的水平及细胞的侵袭能力。结论：NDRG2 可能通过影响CD24 参与调控肝癌细胞的侵袭能力。     

N-Myc Downstream-Regulated Gene 2 (Ndrg2) Is Involved in Ischemia–Hypoxia-Induced Astrocyte Apoptosis: a Novel Target for Stroke Therapy

Nearly all clinical trials that have attempted to develop effective strategies against ischemic stroke have failed, excluding those for thrombolysis, and most of these trials focused only on preventing neuronal loss. However, astrocytes have gradually become a target for neuroprotection in stroke. In previous studies, we showed that the newly identified molecular N-myc downstream-regulated gene 2 (Ndrg2) is specifically expressed in astrocytes in the brain and involved in some neurodegenerative diseases. However, the role of NDRG2 in ischemic stroke remained unclear. In this study, we investigated the role of NDRG2 in middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia and in oxygen–glucose deprivation (OGD)-induced cellular apoptosis in the M1800 astrocyte cell line. NDRG2 mRNA and protein expression began to increase at 6 and 2 h after reperfusion and peaked at 24 h in the ischemic penumbra and in M1800 cells, as detected by RT-PCR and Western blotting. Double immunofluorescence staining showed that the number of apoptotic cells increased as the NDRG2-positive signal increased and that the NDRG2 signal was sometimes co-localized with TUNEL-positive cells and translocated from the cytoplasm to the nucleus in both the ischemic penumbra and the M1800 cells. Using a lentivirus, we successfully constructed two stable astrocytic cell lines in which NDRG2 expression was significantly up- or down-regulated. NDRG2 silencing had a proliferative effect and reduced the percentage of apoptotic cells, reactive oxygen species (ROS) production, and cleaved Caspase-3 protein expression following OGD, whereas NDRG2 over-expression had the opposite effects. In conclusion, NDRG2 is involved in astrocyte apoptosis following ischemic–hypoxic injury, and inhibiting NDRG2 expression significantly reduces ROS production and astrocyte apoptosis. These findings provide insight into the role of NDRG2 in ischemic–hypoxic injury and provide potential targets for future clinical therapies for stroke.     

NDRG3-mediated lactate signaling in hypoxia

Hypoxia is associated with many pathological conditions as well as the normal physiology of metazoans. We identified a lactate-dependent signaling pathway in hypoxia, mediated by the oxygen- and lactate-regulated protein NDRG family member 3 (NDRG3). Oxygen negatively regulates NDRG3 expression at the protein level via the PHD2/VHL system, whereas lactate, produced in excess under prolonged hypoxia, blocks its proteasomal degradation by binding to NDRG3. We also found that the stabilized NDRG3 protein promotes angiogenesis and cell growth under hypoxia by activating the Raf-ERK pathway. Inhibiting cellular lactate production abolishes NDRG3-mediated hypoxia responses. The NDRG3-Raf-ERK axis therefore provides the genetic basis for lactate-induced hypoxia signaling, which can be exploited for the development of therapies targeting hypoxia-induced diseases in addition to advancing our understanding of the normal physiology of hypoxia responses. [BMB Reports 2015; 48(6): 301-302]     

Overexpression of N-Myc Downstream-Regulated Gene 2 (NDRG2) Regulates the Proliferation and Invasion of Bladder Cancer Cells In Vitro and In Vivo

N-Myc downstream-regulated gene 2 (NDRG2) is a candidate tumor suppressor gene, which plays an important role in controlling tumor growth. The aim of this study was to investigate the expression of NDRG2 gene in bladder cancer (BC) tissues and several bladder cancer cell lines, and to seek its clinical and pathological significance. Ninety-seven bladder carcinoma and 15 normal bladder tissue sections were analyzed retrospectively with immunohistochemistry. The human bladder cancer cell line T24 was infected with LEN-NDRG2 or LEN-LacZ. The effects of NDRG2 overexpression on T24 cells and T24 nude mouse xenografts were measured via cell growth curves, tumor growth curves, flow cytometric analysis, western blot and Transwell assay. NDRG2 was highly expressed in normal bladder tissue, but absent or rarely expressed in cacinomatous tissues (χ²=8.761, p < 0.01). The NDRG2 level was negatively correlated with tumor grade and pathologic stage(r=-0.248, p < 0.05), as well as increased c-myc level (r=-0.454, p< 0.001). The expression of NDRG2 was low in the three BC cell lines. T24 cells infected with LEN-NDRG2 showed inhibition of proliferation both in vitro and in vivo, and NDRG2 overexpression can inhibit tumor growth and invasion in vitro.     

NDRG2在人胚胎组织中的表达分布特点

本文旨在研究NDRG2在不同胎龄人胚胎组织中的表达水平及细胞定位。利用RT-PCR和Western blot研究NDRG2 mRNA和蛋白在胎心、肺、肝和肾中的表达水平,免疫组织化学分析NDRG2蛋白在多种胚胎组织中的分布特点。结果表明,NDRG2在胚胎组织中的表达随胚龄的延长而增加。NDRG2 mRNA和蛋白在胎心和肺中的变化一致;在胎肝中mRNA表达低而蛋白表达高,在胎肾中则相反。NDRG2蛋白阳性反应产物存在于细胞胞浆,见于小肠绒毛上皮细胞、结肠上皮细胞、皮肤表层细胞及毛囊、肺内小气道内衬上皮细胞、肝细胞、心肌细胞、胸腺小体、肾小管上皮细胞。结果提示,NDRG2蛋白可能不是一个组织特异性蛋白,并在组织和器官的形成中起作用。