Biomedical subjects

J F Bechberger

Publications and source records attributed to J F Bechberger.

23 records · Page 2Linked to original sources

PubMed1994

Transfection of C6 glioma cells with connexin32: the effects of expression of a nonendogenous gap junction protein.

C6 glioma cells do not express the gap junction protein connexin32 or its corresponding mRNA. Very low levels of connexin43 protein and mRNA, as well as weak intercellular coupling, have been detected. Studies investigating the role of gap junctions in cell proliferation and tumorigenesis have shown that C6 cells transfected with connexin43 have increased levels of intercellular coupling and reduced cell growth (D. Zhu et al., Proc. Natl. Acad. Sci. USA, 88:1883-1887, 1991). To determine whether this growth inhibition is observed with other connexins, a full-length cDNA for connexin32 was used to transfect C6 cells. A number of transfected clones, expressing various levels of connexin32 mRNA, were obtained. Further analysis of several of these clones has shown that they have a corresponding increase in both the amount of connexin32 immunoreactivity and intercellular coupling. Thus, transfection of the C6 glioma cell line with connexin32, a gene which is normally expressed in the rat brain but not in C6 cells, produces both a functional mRNA and protein. Growth of the transfected clones was reduced in vivo. In vitro, growth of the various clones was not correlated to either levels of connexin32 expression or intercellular coupling. This is in contrast to findings in the previous study, in which cell growth was reduced in response to connexin43 expression both in vivo and in vitro in the transfected cells. These clones provide a unique system to study the role of gap junctions in cell proliferation and other tumor characteristics.

Animals↗

PubMed1991

Expression of gap junction genes in astrocytes and C6 glioma cells.

The expression of the gap junction genes coding for the liver-type connexin32 and the heart-type connexin43 was examined in primary cultures of astrocytes and in cultures of C6 glioma cells. In both cell types, only connexin43 mRNA was detectable. However, the level of this mRNA was greatly reduced in C6 glioma cells compared to astrocytes. This was consistent with the further observation that astrocytes in primary culture were extensively dye-coupled, whereas such coupling was very restricted in cultures of C6 glioma cells. Connexin43 was immunocytochemically localized in astrocytes, but was not readily detected in C6 cells.

Animals↗

PubMed1991

Effect of prenatal ethanol exposure on postnatal neural gene expression in the rat.

To examine the effects of ethanol exposure on neural development, pregnant rats were fed a liquid diet in which 37.5% of the total caloric content was ethanol-derived. The developmental appearance of the messenger RNAs coding for preprosomatostatin, glial fibrillary acidic protein, and proteolipid protein was examined by Northern blotting of total cellular RNA obtained from forebrain and hindbrain at various times after birth. In general, there was a delay in the developmental pattern of appearance of these mRNAs which was most noticeable at the early postnatal times. These results suggest that the previously reported delay in neural maturation is reflected at the level of the gene expression.

Animals↗

PubMed1991

Gap junction gene expression in human seizure disorder.

Increased intercellular coupling has been implicated in contributing to the synchronization of discharges characteristic of epileptic foci. Using RNA blot analysis, the level of mRNA for the heart-type gap junction protein, connexin43, is shown to be elevated in samples of temporal lobe neocortex obtained at the time of surgical resection for intractable seizure disorder. Much lower levels of this mRNA are detectable in peritumoral temporal lobe tissue samples obtained during removal of cerebral tumors. However, in cases where the tumors had induced acute seizures, the level of connexin43 mRNA is higher than that detected in epileptic samples. Similar changes are observed for the mRNA for the liver-type gap junction protein, connexin32, although the observed differences are less dramatic. These findings indicate that there is an increase in the level of connexin mRNA in the temporal cortex of patients exhibiting seizure disorders, suggesting an increase in the synthesis of gap junction protein that may lead to an increase in intercellular coupling.

Adolescent↗

PubMed1990

Regional differences in connexin32 and connexin43 messenger RNAs in rat brain.

The regional distribution of gap junction mRNAs was examined in the adult rat brain. The level of connexin43 mRNA is more abundant than connexin32, being homogeneously distributed throughout different regions of brain. In contrast, there is dramatic heterogeneity in the level of connexin32 mRNA, with the highest level in the hindbrain. These results suggest that the gap junction genes are differentially expressed in regions of the adult rat brain.

Animals↗