Altered expression of connexin43 and phosphorylation connexin43 in glioma tumors

In this study, we aim to evaluate the connexin (Cx43) and phosphorylation Cx43 (p-Cx43) expression of human glioma tumors and correlate their expression with degrees of malignancy and proliferation, apoptosis, and migration activity of tumors. Cx43 and p-Cx43 expression were examined by Western blot analysis and immunohistochemical staining. The U251 cell viability was measured by MTT analysis. The apoptosis and migration were also evaluated by flow cytometric analysis and fluoroblok transwell chambers, respectively. We found that the Cx43 expression were significantly downregulated in in malignant glioma (WHO grade III and IV), compared to the malignant glioma (WHO grade I and II) and the p-Cx43 expression levels of malignant glioma (WHO grade III and IV) were significantly increased (P<0.05), compared to the malignant glioma (WHO grade I and II) at immunohistochemical analysis. After treatment of cells with a specific inhibitor of PKC, MAPK, and PTK inhibitors, the cell viability and migration were significantly decreased, while the apoptosis was slightly induced. In conclusion, the Cx43 expression level is inversely correlated with the tumor grade and proliferation and migration activity of tumor. Higher p-Cx43 expression level in high tumor grade suggests that a complex mechanism is involved in the suppression of tumor growth by connexins.     

Molecular interaction of connexin 30.3 and connexin 31 suggests a dominant-negative mechanism associated with erythrokeratodermia variabilis

Connexins are homologous four-transmembrane-domain proteins and major components of gap junctions. We recently identified mutations in either GJB3 or GJB4 genes, encoding respectively connexin 31 (Cx31) or 30.3 (Cx30.3), as causally involved in erythrokeratodermia variabilis (EKV), a mostly autosomal dominant disorder of keratinization. Despite slight differences, phenotypes of EKV Mendes Da Costa (Cx31) and EKV Cram-Mevorah (Cx30.3) show major clinical overlap and both Cx30.3 and Cx31 are expressed in the upper epidermal layers. These similarities suggested to us that Cx30.3 and Cx31 may interact at a molecular level. Indeed, expression of wild-type Cx30.3 in HeLa cell resulted only in minor amounts of protein addressed to the plasma membrane. Mutant Cx30.3 was hardly detectable and disturbed intercellular coupling. In sharp contrast, co-expression of both wild-type proteins led to a gigantic increase of stabilized heteromeric gap junctions. Furthermore, co-expressed wild-type Cx30.3 and Cx31 coprecipitate, which demonstrates a physical interaction. Inhibitor experiments revealed that this interaction begins in the endoplasmic reticulum. These results not only provide new insights into epidermal connexin synthesis and polymerization, but also allow a novel molecular explanation for the similarity of EKV phenotypes.     

缝隙连接蛋白43在骨关节炎软骨及细胞中表达及shRNA慢病毒载体的构建

文题释义：缝隙连接蛋白43(connexin43)：在维持关节软骨代谢平衡的稳态中发挥着至关重要的作用, 它所参与形成的半通道(hemichannel)和缝隙连接(gap junction)在细胞与细胞外基质,以及细胞之间建立起直接的物质信号交换通道。同时,缝隙连接蛋白43的高表达和分布的变化都将影响软骨细胞结构和功能的完整性。 小发卡或短发卡RNA(a small hairpin RNA or short hairpin RNA,shRNA)：是一段具有紧密发卡环的RNA序列,常被用于RNA干扰沉默靶基因的表达。利用载体把shRNA导入细胞,载体中的U6 启动子确保shRNA总是表达;这种装载了shRNA的载体可被传递到子代细胞中去,从而使基因的沉默可被遗传。 293T细胞：293细胞是人肾上皮细胞系,有多种衍生株,比如HEK293,293T/17等,来源都是人胚胎肾细胞,其极少表达细胞外配体所需的内生受体,且比较容易转染,是一个很常用的表达研究外源基因的细胞株。293T细胞由293细胞通过基因技术派生出的细胞系,广泛应用于病毒包装。 背景：缝隙连接蛋白43在骨关节炎的发生发展中具有重要作用,但具体机制尚不明确。 目的：通过体内和体外实验检测缝隙连接蛋白43在骨关节炎软骨和细胞中的表达,验证骨关节炎软骨及软骨细胞(SW1353)中缝隙连接蛋白在连接蛋白家族的主导地位;构建缝隙连接蛋白基因的shRNA慢病毒载体,建立SW1353细胞的稳定转染细胞株。 方法：C57BL/6小鼠6只,通过前交叉韧带横切术建立小鼠骨关节炎动物模型,通过免疫组织化学染色检测骨关节炎与正常关节中缝隙连接蛋白表达水平的差异。采用RT-PCR技术检测SW1353细胞中缝隙连接蛋白43 mRNA的表达,同时检测SW1353细胞中缝隙连接蛋白37、40、45和46基因的表达水平作为对照。将缝隙连接蛋白43 mRNA连接到含有增强型绿色荧光蛋白基因的慢病毒载体中,重组获得慢病毒质粒,将其与辅助包装质粒共转染293T细胞。所获慢病毒载体感染SW1353细胞后,检测缝隙连接蛋白43的表达。实验方案经口腔疾病研究国家重点实验室伦理委员会批准(批准号为SKLODLL2013A172)。 结果与结论：①缝隙连接蛋白43在小鼠骨关节炎软骨组织中的表达较健康关节明显增加;②缝隙连接蛋白43 mRNA在SW1353细胞中的表达明显高于缝隙连接蛋白37、40、45和46的基因表达,SW1353细胞中的缝隙连接蛋白43在连接蛋白家族中具有主导地位;③缝隙连接蛋白43 shRNA慢病毒载体可抑制SW1353细胞中缝隙连接蛋白43 mRNA的表达;④实验筛选出稳定转染的SW1353细胞株,为验证缝隙连接蛋白43在骨关节炎中的作用机制奠定了基础。 ORCID: 0000-0003-4545-9694(薛俊杰) 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

间隙连接蛋白43在舌黏膜癌变过程中的表达

目的 研究间隙连接蛋白43(connexin 43,Cx43)在口腔黏膜癌变过程中的表达变化,探寻其与口腔黏膜癌变的关系及意义.方法 用4亚基硝氧喹啉(4-nitroquinoline-1-oxide,4NQO)诱导SD大鼠口腔黏膜癌变,应用免疫组化方法检测Cx43在口腔黏膜癌变过程中各阶段的动态变化,分析Cx43与口腔黏膜癌变的关系.结果 Cx43蛋白主要表达于大鼠舌黏膜上皮细胞的胞膜、上皮基底层、棘层和颗粒层呈阳性染色,角质层未见表达.随着舌黏膜上皮异常增生程度的增加,Cx43的表达明显下降.在口腔鳞状细胞癌组织中,Cx43染色分布于癌细胞胞质以及鳞癌组织的角化珠内.Cx43在正常舌黏膜、轻度上皮异常增生、中度上皮异常增生、重度上皮异常增生、口腔鳞癌组织中阳性表达率分别为100.00％(10/10)、85.71％(12/14)、66.67％(8/12)、40.00％(4/10)、33.33％(4/12),差异有统计学意义(P＜0.05).结论 4NQO诱发舌黏膜癌变的过程中,Cx43蛋白表达水平随病变程度加重而显著下降,提示Cx43表达异常参与了口腔黏膜的癌变过程.Cx43表达下降是口腔黏膜癌变的早期事件.     

Spontaneous lung dysfunction and fibrosis in mice lacking connexin 40 and endothelial cell connexin 43

Gap junction proteins (connexins) facilitate intercellular communication and serve several roles in regulation of tissue function and remodeling. To examine the physiologic effects of depleting two prominent endothelial connexins, Cx40 and Cx43, transgenic mice were generated by breeding Cx40-deficient mice (Cx40(-/-)) with a vascular endothelial cell (VEC)-specific Cx43-deficient mouse strain (VEC Cx43(-/-)) to produce double-connexin knockout mice (VEC Cx43(-/-)/Cx40(-/-)). The life span in VEC Cx43(-/-)/Cx40(-/-) mice was dramatically shortened, which correlated with severe spontaneous lung abnormalities as the mice aged including increased fibrosis, aberrant alveolar remodeling, and increased lung fibroblast content. Moreover, VEC Cx43(-/-)/Cx40(-/-) mice exhibited cardiac hypertrophy and hypertension. Because VEC Cx43(-/-)/Cx40(-/-) mice demonstrated phenotypic hallmarks that were remarkably similar to those in mice deficient in caveolin-1, pulmonary caveolin expression was examined. Lungs from VEC Cx43(-/-)/Cx40(-/-) mice demonstrated significantly decreased expression of caveolin-1 and caveolin-2. This suggests that expression of caveolin-1 may be linked to expression of Cx40 and endothelial Cx43. Moreover, the phenotype of caveolin-1(-/-) mice and VEC Cx43(-/-)/Cx40(-/-) mice may arise via a common mechanism.     

新生儿心肌连接蛋白43、45的表达

目的　研究新生儿心肌不同部位连接蛋白 4 3、4 5 (Cx4 3、Cx4 5 )表达的差异。方法　应用SP免疫组化方法 ,分析和比较 6例新生儿心不同腔室心肌细胞Cx4 3、Cx4 5的表达。结果　 1 新生儿心肌Cx4 3的蛋白表达在心四个腔均有表达 ,呈斑点状遍布于整个心房肌和心室肌的细胞质内和细胞膜表面 ,少数位于闰盘处 ;Cx4 3、主要在心室肌表达 ,心房较少 ;2 Cx4 3与Cx4 5的分布类似 ,但远少于Cx4 3。结论　Cx4 3主要分布于新生儿心肌细胞质内和细胞表面。心室表达多于心房 ,Cx4 5和Cx4 3分布相似 ,但不如Cx4 3丰富。     

Cx43在造血调控及重建中的作用

目的:采用条件性基因敲除技术构建造血系统间隙连接蛋白43(Cx43)基因敲除(Cx43~(-/-))小鼠模型,并探讨Cx43在维持造血细胞自我更新及功能稳定中的作用。方法:将引进的2对转基因小鼠Cx43 loxP/loxP和Lyz-Cre/+杂交,选取F1雌性子代Cx43 loxP/-_Lyz-Cre/+与雄性Cx43 loxP/loxP合笼回配,提取所获得子代小鼠鼠尾组织基因组DNA,采用PCR方法鉴定小鼠基因型,RT-PCR方法筛选Cx43~(-/-)小鼠,同时分析小鼠不同器官中Cx43基因的表达差异;该类小鼠经5-氟尿嘧啶(5-FU;125 mg/kg)处理,在化疗前及化疗后第5、10和15天经眼球取血分析其血象变化。Cx43~(-/-)及Cx43~(+/+)小鼠予7.5 Gy(~(60)Co-γ)的致死量照射,剂量率1 Gy/min,照射后6 h分别给予事先准备就序的骨髓细胞,每只3×10~6细胞于尾静脉注入,2周后处死小鼠检测造血是否重建:分离股骨切片后,收集骨髓细胞进行细胞表型分析(选用的单抗为CD45R、Gr-1、CD4、 CD8a、TCRαβ、Mac-1、抗sIgM、TER119、Sca-1及CD117);同时进行体外造血细胞集落实验观察造血细胞的体外增殖能力。结果:本研究通过2种转基因小鼠间杂交和回交,成功获得造血系统选择性Cx43基因敲除小鼠;该类小鼠骨髓及外周血细胞无Cx43表达,参与造血的组织,如肝脏和脾脏中Cx43表达也显著下调(P0.01),而心脏和肾脏的Cx43表达则无影响,小鼠成年后外周血象分析并无明显异常,但应急代偿能力下降,经5-FU处理后,其造血功能恢复显著减缓,处理15 d后,Cx43~(+/+)小鼠造血功能已接近正常水平,而Cx43~(-/-)小鼠仍无明显的恢复迹象,血红蛋白、白细胞及血小板仍处低位,2者差别有统计学显著性(P0.01);体外集落试验也证实Cx43~(-/-)小鼠造血干/祖细胞的增殖能力下降,其CFU-GM或CFU-E集落数均明显少于Cx43~(+/+)小鼠(P0.01),但流式细胞术结果显示,Cx43~(-/-)小鼠骨髓中Lin~-/c-Kit~+/Sca-1~+细胞亚群数量与Cx43~(+/+)小鼠相比差异并无统计学显著性;Cx43~(-/-)小鼠在化疗或移植后其骨髓造血功能重建均延迟,且化疗15 d后骨髓切片及涂片均证实其骨髓中造血细胞增生程度明显降低,脂肪组织显著增多,而且T、B细胞发育也有异常。此外,其外周血中CD4~+CD8~+细胞比例比野生型小鼠增多(P0.05),但CD4~+T细胞显著减少(P0.01),尤其是TCRαβ亚群细胞减少最为明显(P0.01)。同样,Cx43~(-/-)小鼠外周血中CD45R~+sIgM~-细胞亚群比例与野生型小鼠相比显著减少(P0.01)。结论:骨髓中Cx43基因表达在造血干/祖细胞发育(尤其是应急状态时)具重要作用,敲除Cx43基因后造血干/祖细胞增殖减缓,造血及免疫重建功能受损。     

实验性病毒性心肌炎时穿孔素和连接蛋白43表达的相关性

目的：探讨病毒性心肌炎时穿孔素和心肌细胞缝隙连接蛋白43表达的关系。方法：应用免疫组织化学EnVision法对实验性病毒性心肌炎小鼠心肌组织中穿孔素、连接蛋白43的表达进行观察。结果：正常小鼠心肌中未见穿孔素阳性表达，连接蛋白43在心肌闰盘中呈阳性表达。心肌炎组织中部分浸润的炎细胞穿孔素呈阳性表达。在穿孔素阳性表达外，连接蛋白43表达明显减弱甚至阴性。结论：在病毒性心肌炎时穿孔素直接影响到连接蛋白43的正常表达，是引起连接蛋白43阴性表达及异常表达的主要因素之一。     

实验性病毒性心肌炎组织中连接蛋白43和结蛋白的表达

目的 了解病毒性心肌炎时心肌细胞连接蛋白４３和结蛋白表达情况,以探讨病毒性心肌炎时心律失常的机制。方法 应用免疫组织化学ＳＡＢＣ法,对实验性病毒性心肌炎小鼠心肌细胞连接蛋白４３和结蛋白的表达进行了观察。结果 连接蛋白４３和结蛋白在正常小鼠心肌闰盘中定位分布,均匀存在,后者还在肌节横纹中显示阳性;病毒性心肌炎时两者的表达明显减弱甚至阴性。结论 病毒性心肌炎时受累的心肌细胞连接蛋白４３和结蛋白的表达受     

连接蛋白43在培养心肌肥大时的表达及其意义

目的研究培养心肌连接蛋白４３（Ｃｘ４３）的表达及与心肌肥大的关系。方法分离培养大鼠心肌细胞,用去甲肾上腺素（ＮＥ）或苯肾上腺素（ＰＥ）诱导心肌肥大,用免疫组化方法观察心肌细胞Ｃｘ４３、增殖细胞核抗原（ＰＣＮＡ）及ｃｄｃ２表达,以图像分析系统检测Ｃｘ４３表达量的变化。结果在培养中加ＮＥ或ＰＥ的心肌细胞,Ｃｘ４３表达明显低于对照组,而其ＰＣＮＡ的阳性率明显高于对照组。ｃｄｃ２阳性率不变。结论在ＮＥ或ＰＥ作用下,培养大鼠心肌细胞中Ｃｘ４３表达下降,与细胞进入Ｓ期有关,这可能是两者促进心肌肥大的机制     

Ischaemia-induced temporal expression of connexin43 in rat heart

 To investigate the regulation of cell-to-cell coupling in myocardial ischaemia, the three-dimensional expression of connexin43 (Cx43) during experimental ischaemia was examined using a confocal laser scanning microscope. After induction of myocardial infarction in rats, serial optical sections were obtained from the left ventricular myocardium at various times (3 h to 60 days after ligation). The expression of Cx43 was detected immunohistochemically with FITC-labelled anti-rat Cx43 antibody. Fluorescent dots of Cx43 remained along the intercalated disc and decreased in number around the infarct up to 12 h after ligation. Cx43-expression disappeared completely within 48 h after ligation. After day 4, and especially on days 8 and 15 after ligation, the edges of the cardiomyocytes bordering the infarcted area manifested numerous sarcoplasmic tentacles that reacted positively to anti-desmin antibody. Distinct expression of Cx43 was observed extensively on the tentacles, although no cardiomyocytes remained viable around them. By day 60 after ligation, atypical expression of Cx43 had disappeared. These findings suggest that ischaemia induces temporally abnormal expression of Cx43, which might be responsible for abnormal conduction around the infarct. Received: 4 April 1997 / Accepted: 19 June 1997     

连接蛋白43在病理性瘢痕成纤维细胞中的表达

目的:探讨连接蛋白43(Cx43)及其构成的缝隙连接细胞间通讯(GJIC)在病理性瘢痕中的调控作用.方法:选择临床上不同病理分类的瘢痕组织(包括瘢痕疙瘩、增生性瘢痕)和正常修复组织,以正常皮肤为对照,应用免疫组织化学检测Cx43在成纤维细胞中的表达.结果:Cx43在增生性瘢痕和瘢痕疙瘩成纤维细胞中的表达明显少于正常修复组织及正常皮肤.结论:成纤维细胞Cx43的表达下调可能是造成病理性瘢痕组织中成纤维细胞间GJIC异常,从而导致病理性瘢痕发生的因素之一.     

Expression of gap junction proteins connexin 26 and connexin 43 in normal human breast and in breast tumours

Gap junctional intercellular communication (GJIC) has been proposed as a cellular mechanism for tumour suppression and there is experimental evidence in support of this. If aberrant GJIC contributes to the formation of human breast tumours, one might expect that the connexins (gap junction proteins) expressed by epithelial cells in normal human breast would be down-regulated in tumour epithelial cells, or that tumour cells might show aberrant expression of other connexin family members. This study examines the immunocytochemical expression of connexins 26 (Cx26) and 43 (Cx43) in normal human breast, 11 benign breast lesions, two special-type carcinomas, and 27 invasive carcinomas of no special histological type (NST). Cx26 generally was not expressed at detectable levels in normal human breast, but punctate Cx43 immunostaining of the myoepithelial cells was found. Cx43 staining of the myoepithelium was also a feature of the benign lesions and ductal carcinoma in situ (DCIS). In general, the epithelial cells of benign lesions failed to stain for either connexin. Similarly, a lobular carcinoma did not express Cx26 or Cx43, but there was punctate Cx43 in the epithelial cells of a mucoid carcinoma. Cx26 was up-regulated in the carcinoma cells of 15 of the 27 invasive NST carcinomas, although the staining was usually cytoplasmic and heterogeneous. Cx43 was expressed by stromal cells, possibly myofibroblasts, in all NST carcinomas. Furthermore, there was heterogeneous Cx43 expression in the carcinoma cells of 14 of the 27 NST carcinomas and the staining was often intercellular and punctate, characteristic of functional connexins. Up-regulation of Cx26 and/or Cx43 in the carcinoma cells of over two-thirds of invasive lesions of NST is not necessarily inconsistent with a tumour suppressor role for GJIC. However, the role of gap junctions in the formation and progression of solid human tumours is likely to be more complex than indicated from experimental systems. © 1998 John Wiley & Sons, Ltd.     

发育大鼠心肌细胞间隙连接蛋白43表达特性

目的：探讨大鼠心肌细胞间隙连接蛋白43(Cx43)表达的发育特性。方法：应用SP免疫组化和图像分析方法,观察胎大鼠、出生1 d、5 d、10 d和25 d大鼠心肌细胞Cx43的蛋白表达。结果：(1)胎鼠心肌细胞Cx43呈斑点状遍布于心肌细胞侧—侧连接、细胞质内和闰盘处。(2)出生后1 d大鼠心肌细胞的Cx43分布与胎鼠相似,5 d和10 d组逐渐向闰盘处聚集。25 d时部分已聚集于端闰盘处,其余仍呈斑点状散在分布。(3)出生前后心室肌细胞Cx43分布有差异。分布密度总规律是：胎大鼠＞出生1 d＞5 d＞10 d＞25 d。结论：出生前后大鼠心肌细胞Cx43分布随心脏发育逐渐向闰盘处重排,其分布密度呈逐渐下降趋势。     

缝隙连接蛋白43和黄体生成素受体在小鼠卵巢中的表达

目的 观察小鼠卵泡发育过程中缝隙连接蛋白43（Cx43）和黄体生成素受体（LHR）在小鼠卵巢中的表达以及黄体生成素(LH)对卵巢Cx43表达的影响,为这两种分子与卵泡发育的关系提供实验依据。 方法 选择出生后1d、4d、7d、2周、3周、4周、6周、8周龄雌性C57小鼠共8组,每组10只,取卵巢。HE染色观察卵巢形态、卵泡发育并测量颗粒细胞体积分数。免疫组织化学和Western blotting观察卵巢组织中Cx43及LHR的表达,Western blotting检测不同浓度黄体生成素（LH）孵育后对卵巢Cx43表达的影响。 结果 HE染色显示,出生1d小鼠卵巢中见原始卵泡,出生7d卵巢内出现初级卵泡,2周时出现窦前卵泡和少量窦卵泡,3周、4周时,出现较多大的窦卵泡,6～8周时出现黄体。卵泡颗粒细胞体积分数在2周后的卵巢中明显增加。Cx43表达在各阶段卵泡的颗粒细胞胞膜上,LHR表达在卵泡膜细胞、颗粒细胞及卵母细胞胞质中。Cx43和LHR出生后2周卵巢中的表达开始明显增加,并随卵泡发育表达逐渐增强,在3周、4周、6周和8周维持相对较高水平。LH体外干预可增加卵巢组织Cx43的表达。 结论 Cx43和LHR在卵泡发育中发挥重要作用,LH可能通过LHR促进卵巢卵泡颗粒细胞Cx43的表达。     

Modulation of connexin 43 in rotenone-induced model of Parkinson's disease

Gap junctional communication plays an important role in various models of brain pathology, but the changes of gap junctions in Parkinsonism are still not understood. In this study, we show that a major gap junctional protein, connexin43 (Cx43), in astrocytes is enhanced both in a rat Parkinson's disease (PD) model induced with rotenone, a widely used pesticide that inhibits mitochondrial complex I, and in vitro in cultured astrocytes stimulated with rotenone. Enhancement of Cx43 protein levels in rotenone-treated cultured astrocytes occurred in parallel with an increase in gap junctional intercellular communication, but was not accompanied with an increase in Cx43 mRNA levels. Furthermore, the rotenone-induced increase of Cx43 protein levels both in vitro and in vivo was associated with increased levels of phosphorylated Cx43, which is required for gap junctional intercellular communication. In our rat PD model, phosphorylated Cx43 was selectively enhanced in the basal ganglia regions, which contain DA neurons or their terminal areas. The increase of Cx43 levels was lower in the substantia nigra pars compacta and the striatum than in the substantia nigra pars reticulata and the globus pallidus. Our findings indicate that modulation of Cx43 protein, and consequently gap junctional cellular communication, in astrocytes may play an important role in PD pathology.     

Immunohistochemical analysis of connexin43 expression in infertile human testes

Connexin43 (Cx43) is abundantly expressed in mammalian testes and implicated in the regulation of cell-to-cell interaction between germ cells and Sertoli cells, which is essential to the normal process of spermatogenesis. In the present study, we investigated the relation between Cx43 expression and the degree of spermatogenesis in infertile human testes. Immunohistochemical analysis of Cx43 was performed on testicular biopsies from 29 patients with azoospermia (n=23) and severe oligospermia (n=6), who gave informed consent to this experiment. The degree of testicular spermatogenesis was evaluated by Johnsen score. In the interstitium, immunostaining for Cx43 was localized to some focal parts of plasma membrane between neighboring Leydig cells. In seminiferous tubules with normal spermatogenesis, Cx43 expression was found between Sertoli cells and germ cells. However, Cx43 expression in maturation arrest was decreased and located mainly in the basal compartment of seminiferous tubules. Finally, there was a significant positive correlation between histological score of spermatogenesis and intensity of Cx43 (p=0.0294). These data suggest that the alteration of Cx43 expression may be involved in spermatogenic impairment, and that the communication between Sertoli cells and germ cells through Cx43 may be important for maturation of spermatogenesis.     

In vivo and in vitro expression of connexin 43 in human teeth

Gap junctions are composed of transmembrane proteins belonging to the connexin family. These proteins permit the exchange of mall regulatory molecules directly between cells for the control of growth, development and differentiation. Although the presence of gap junctions in teeth has been already evidenced, the involved connexins have not yet been identified in human species. Here, we examined the distribution of connexin 43 (Cx43) in embryonic and permanent intact and carious human teeth. During tooth development, Cx43 localized both in epithelial and mesenchymal dental cells, correlated with cytodifferentiation gradients. In adult intact teeth, Cx43 was distributed in odontoblast processes. While Cx43 expression was downregulated in mature intact teeth, Cx43 appeared to be upregulated in odontoblasts facing carious lesions. In cultured pulp cells, Cx43 expression was related to the formation of mineralized nodules. These results indicate that Cx43 expression is developmentally regulated in human dental tissues, and suggest that Cx43 may participate in the processes of dentin formation and pathology.