Ciliary Defects in a Mouse Model of Bardet-Biedl Syndrome are Selectively Pronounced in Brian Regions Involved in Cardiovascular Regulation.

Bardet-Biedl syndrome (BBS) is a human genetic disorder associated with several phenotypes including hypertension. Here we used the hypertensive Bbs4 knockout mouse model (Bbs4-/-) to test the hypothesis that areas of the brain involved in cardiovascular regulation (CVR) exhibit abnormalities in primary neuronal cilia (PNC) structure and density. We utilized immunocytochemical localization of adenylyl cyclase-III (ACIII), a specific marker for PNC, to identify the changes in PNC length and density in commissural nucleus of solitary tract (cNTS), area postrema (AP), rostroventrolateral medulla (RVLM) and subfornical organ (SFO). A quantitative analysis of the morphology and distribution of ACIII-immunoreactive PNC revealed dramatic alterations in the length and number of cilia in SFO of Bbs4-/- mice compared to wild type (WT) littermates. The significant reduction in the PNC length but not in the number was observed in cNTS and RVLM. Surprisingly, no significant changes in length and distribution of PNC were documented in the AP. We found that in all investigated areas of the brain the number of neurons did not display significant changes in Bbs4-/- when compared to the corresponding areas of WT mice. This data suggests that loss of the Bbs4 gene differentially affects the PNC in the brain areas involved in CVR; and the pathology of PNC in selected regions of CVR can cause a failure in signal transduction and may contribute to the hypertension associated with Bbs4-/- mouse model.

Serum deprivation-induced apoptosis in cultured hippocampi is prevented by kainate.

Serum deprivation of hippocampal organotypic cultures induced cell death within 6 h in dentate gyrus granule cells and hilar interneurons whereas neurons from other hippocampal regions were spared. Dying neurons exhibited condensed chromatin in the nuclei, as revealed by cresyl violet, Hoescht staining, and electron microscopy. Cell death was abolished by cycloheximide. KA, an agonist of AMPA/KA receptors that induces depolarization, also prevented neuronal death. This effect was antagonized by the AMPA/KA receptor antagonist DNQX, but not by APV, an antagonist of NMDA receptors. PTX, a GABA(A) receptor antagonist, reduced neuronal death by 50% after serum withdrawal. These data indicate that protein synthesis-dependent programmed cell death (PCD) occurs in the dentate gyrus upon trophic support withdrawal and suggest that neuronal activity contributes to cellular homeostasis.

Subcellular distribution of calponin and caldesmon in rat hippocampus.

Caldesmon and calponin are two actin- and calmodulin-binding proteins involved in the 'actin-linked' regulation of smooth muscle and non-muscle Mg(2+)-actin-activated myosin II ATPase activity. In the present report we show that caldesmon and calponin are present in the post-synaptic side of symmetric synapses and accumulate in the post-synaptic densities of asymmetric synapses. Caldesmon- and calponin-immunoreactivities are also observed at the plasma membrane of the hippocampal neurones. Finally, while caldesmon seems strictly distributed to neurones, acidic calponin is present in both neurones and astrocytes.

Distribution of caldesmon and of the acidic isoform of calponin in cultured cerebellar neurons and in different regions of the rat brain: an immunofluorescence and confocal microscopy study.

Caldesmon and calponin are two F-actin-binding and calcium-calmodulin-dependent proteins. In smooth muscle and nonmuscle cells both proteins are localized on actin filaments. Using one- or two-dimensional gel electrophoresis followed by the Western blot technique, and by immunofluorescence studies, we have given evidence that calponin is also present in rat and pig brain. In the present study, for the first time, we demonstrate caldesmon- and calponin-specific immunoreactivities in cerebellar cultured neurons. In the rat central nervous system these antibodies mainly stain neuronal cell bodies and dendrites. By confocal analysis we observed that calponin and caldesmon are located in the actomyosin domain although the total actin and myosin were not saturated. In many cases it is clear that these two proteins are adjacent rather than superimposed in the same domain of the cell. These results are compatible with the functional role of caldesmon and calponin in the regulation of the actomyosin activity as described by others and suggest that they are part of the contractile apparatus of neural cells.