Expression of the gap junction protein connexin43 in the subependymal layer and the rostral migratory stream of the mouse: evidence for an inverse correlation between intensity of connexin43 expression and cell proliferation activity.

Connexins constitute the channel-forming proteins of gap junctions. Gap junctions are considered to be involved in the regulation of cell proliferation. To verify this hypothesis for connexin43, the most abundant connexin in brain tissue, we have analyzed the expression of this gap junction protein in the subependymal layer and the rostral migratory stream of the murine telencephalon.

Mitral and tufted cells of the mouse olfactory bulb possess gap junctions and express connexin43 mRNA.

Analyses of freeze-fracture replicas of mouse olfactory bulb reveal the presence of gap junctions in the plasma membranes of the cell bodies of mitral cells. Due to their localization and morphology we presume that they interconnect mitral and granule cells. Since the quality of electrical transmission between neurons is considered to be determined by the biochemical nature of the gap junction channel forming proteins (connexins) we performed immunohistochemistry and in situ hybridization using probes for connexin43 (Cx43), the most abundant connexin in brain tissue.

Immunolocalization of the neural cell adhesion molecule L1 in non-proliferating epithelial cells of the male urogenital tract.

The localization of the neural cell adhesion molecule L1 in the male urogenital tract (including seminal vesicles and prostate) of the mouse and bull was investigated using immunocytochemical and immunochemical methods in order to better understand the function of this glycoprotein in non-neural tissues. L1 antibodies labeled non-myelinated nerves in all portions of the urogenital tract investigated. However, L1 immunoreactivity was also found between epithelial cells of several regions of the urogenital system including epididymal tail, deferent duct, ejaculatory duct and seminal vesicles.

Expression of the tight junction protein ZO-1 in the olfactory system: presence of ZO-1 on olfactory sensory neurons and glial cells.

The olfactory system is a unique part of the central nervous system since it retains neuronal turnover and regenerative capacities in adulthood. Thus it provides an ideal model to study plasticity of membrane moities involved in cell-cell interactions. One structure particularly involved in cell-cell interaction is the tight junction, which establishes polarization of epithelial cells and creates diffusion barriers to paracellular passages.

Expression of connexins in the developing olfactory system of the mouse.

To gain insight into the function of gap junctions' connexin43, connexin32 and connexin26 in a neural structure that retains neuronal turnover capacities throughout adulthood, the expression of these molecules has been investigated in the developing and adult olfactory system by immunocytochemical and biochemical methods. Connexin43 was detectable from the olfactory placode stage. During early embryonic development, the levels of connexin43 expression remained low.