Previous studies have provided evidence for the transcripts of Cx43 and Cx45 within pancreatic islets. As of yet, however, it has proven difficult to unambiguously demonstrate the expression of these proteins by islet cells. We have investigated whether Cx36, a new connexin species recently identified in mammalian brain and retina, may also be expressed in pancreatic islets. Using probes that permitted the original identification of Cx36 in the central nervous system, we show that a transcript for Cx36 is clearly detectable in rat pancreatic islets. Using novel and affinity-purified polyclonal antibodies, we have found that Cx36 is actually expressed in pancreatic islets. Both in situ hybridization and immunolabeling indicated that this connexin is abundant in the centrally located insulin-producing

The identification of connexins (Cxs) expressed in neuronal cells represents a crucial step for understanding the direct communication between neurons and between neuron and glia. In the present work, using a double-labelling method combining in situ hybridization for Cx mRNAs with immunohistochemical detection for neuronal markers, we provide evidence that, among cerebral connexins (Cx26, Cx32, Cx36, Cx37, Cx40, Cx43, Cx45 and Cx47), only Cx45 and Cx36 mRNAs are localized in neuronal cells in both developing and adult rat brain. In order to establish whether connexin expression is influenced in vivo by abnormal neuronal activity, we examined the short-term effects of kainate-induced seizures. The results revealed an unexpected expression of Cx26 and Cx45 mRNA in neuronal cells undergoing apoptotic cell death in the CA3-CA4, in the hilus of the hippocampus and in other brain regions involved in seizure-induced lesion. However, the expression of Cx26 and Cx45 mRNAs was not associated with detectable expression of corresponding proteins as evaluated by immunohistochemistry with specific antibodies. Moreover, in the same brain regions Cx32 and Cx43 were up-regulated in non-neruronal cells whereas the neuronal Cx36 was down-regulated. Taken together the present results provide novel information regarding the specific subpopulation of neurons expressing Cx45 and raise the question of the meaning of connexin mRNA expression in the neuronal apoptotic process.

Copper homeostasis and distribution is strictly regulated by a network of transporters and intracellular chaperones encoded by a group of genes collectively known as copper homeostasis genes ( CHG s). In this work, analysis of The Cancer Genome Atlas database for somatic point mutations in colorectal cancer revealed that inactivating mutations are absent or extremely rare in CHG s. Using oligonucleotide microarrays, we found a strong increase in mRNA levels of the membrane copper transporter 1 protein [ CTR 1; encoded by the solute carrier family 31 member 1 gene ( SLC 31A1 gene)] in our series of colorectal carcinoma samples. CTR 1 is the main copper influx transporter and changes in its expression are able to induce modifications of cellular copper accumulation. The increased SLC 31A1 mRNA level is accompanied by a parallel increase in transcript levels for copper efflux pump ATP 7A, copper metabolism Murr1 domain containing 1 ( COMMD 1), the cytochrome C oxidase assembly factors [synthesis of cytochrome c oxidase 1 ( SCO 1) and cytochrome c oxidase copper chaperone 11 ( COX 11)], the cupric reductase six transmembrane epithelial antigen of the prostate ( STEAP 3), and the metal‐regulatory transcription factors ( MTF 1, MTF 2) and specificity protein 1 ( SP 1). The significant correlation between SLC 31A1 , SCO 1 , and COX 11 mRNA levels suggests that this transcriptional upregulation might be part of a coordinated program of gene regulation. Transcript‐level upregulation of SLC 31A1 , SCO 1 , and COX 11 was also confirmed by the analysis of different colon carcinoma cell lines (Caco‐2, HT 116, HT 29) and cancer cell lines of different tissue origin ( MCF 7, PC 3). Finally, exon‐level expression analysis of SLC 31A1 reveals differential expression of alternative transcripts in colorectal cancer and normal colonic mucosa.

Rationale: Gap junctions are membrane channels formed by an array of connexins which links adjacent cells realizing an electro-metabolic synapse. Connexin-mediated communication is crucial in the regulation of cell growth, differentiation, and development. The activation and proliferation of phenotypically altered fibroblasts are central events in the pathogenesis of idiopathic pulmonary fibrosis. We sought to evaluate the role of connexin-43, the most abundant gap-junction subunit in the human lung, in the pathogenesis of this condition. Methods:We investigated the transcription and protein expression of connexin-43 and the gapjunctional intercellular communication (GJIC) in 5 primary lung fibroblast lines derived from normal subjects (NF) and from 3 histologically proven IPF patients (FF). Results:Here we show that connexin-43 mRNA was significantly reduced in FF as demonstrated by standard and quantitative RT-PCR. GJIC was functionally evaluated by means of flow-cytometry. In order to demonstrate that dye spreading was taking place through gap junctions, we used carbenoxolone as a pharmacological gap-junction blocker. Carbenoxolone specifically blocked GJIC in our system in a concentration dependent manner. FF showed a significantly reduced homologous GJIC compared to NF. Similarly, GJIC was significantly impaired in FF when a heterologous NF line was used as dye donor, suggesting a complete defect in GJIC of FF. Conclusion:These results suggest a novel alteration in primary lung fibroblasts from IPF patients. The reduced Cx43 expression and the associated alteration in cell-to-cell communication may justify some of the known pathological characteristic of this devastating disease that still represents a challenge to the medical practice.

We have identified a novel gap junction gene by searching the human genome sequence database that encodes a protein designated as connexin31.9 (Cx31.9). Cx31.9 was most homologous to human Cx32.4 and did not cluster with either the purported alpha- or beta-connexin subfamilies. Expression of Cx31.9 was detected by RT-PCR in human mRNA from several tissues including cerebral cortex, heart, liver, lung, kidney, spleen, and testis. A partial Cx31.9 sequence was also represented in the human Expressed Sequence Tag database. Cx31.9 formed intercellular channels in both paired Xenopus oocytes and transfected neuroblastoma N2A cells that were distinguished by an apparent low unitary conductance (12-15 pS) and a remarkable insensitivity to transjunctional voltage. In contrast, Cx31.9 channels were gated by cytoplasmic acidification or exposure to halothane like other connexins. Cx31.9 was able to form heterotypic channels with the highly voltage-sensitive Xenopus Cx38 (XenCx38), which provides an opportunity to study gating in heterotypic channels formed by hemichannels (connexons) composed of connexins with widely divergent properties. Thus Cx31.9 is a novel human connexin that forms channels with unique functional properties.