Phenotype plasticity and immunocytochemical evidence for ChAT and D beta H co-localization in fetal pig superior cervical ganglion cells

Purification of Functional Human TRP Channels Recombinantly Produced in Yeast

(1) Background: Human transient receptor potential (TRP) channels constitute a large family of ion-conducting membrane proteins that allow the sensation of environmental cues. As the dysfunction of TRP channels contributes to the pathogenesis of many widespread diseases, including cardiac disorders, these proteins also represent important pharmacological targets. TRP channels are typically produced using expensive and laborious mammalian or insect cell-based systems. (2) Methods: We demonstrate an alternative platform exploiting the yeast Saccharomyces cerevisiae capable of delivering high yields of functional human TRP channels. We produce 11 full-length human TRP members originating from four different subfamilies, purify a selected subset of these to a high homogeneity and confirm retained functionality using TRPM8 as a model target. (3) Results: Our findings demonstrate the potential of the described production system for future functional, structural and pharmacological studies of human TRP channels.

Localization of peripheral autonomic neurons innervating the boar urinary bladder trigone and neurochemical features of the sympathetic component

The urinary bladder trigone (UBT) is a limited area through which the majority of vessels and nerve fibers penetrate into the urinary bladder and where nerve fibers and intramural neurons are more concentrated. We localized the extramural post-ganglionic autonomic neurons supplying the porcine UBT by means of retrograde tracing (Fast Blue, FB). Moreover, we investigated the phenotype of sympathetic trunk ganglia (STG) and caudal mesenteric ganglia (CMG) neurons positive to FB (FB+) by coupling retrograde tracing and double-labeling immunofluorescence methods. A mean number of 1845.1±259.3 FB+ neurons were localized bilaterally in the L1-S3 STG, which appeared as small pericarya (465.6±82.7 µm²) mainly localized along an edge of the ganglion. A large number (4287.5±1450.6) of small (476.1±103.9 µm²) FB+ neurons were localized mainly along a border of both CMG. The largest number (4793.3±1990.8) of FB+ neurons was observed in the pelvic plexus (PP), where labeled neurons were often clustered within different microganglia and had smaller soma cross-sectional area (374.9±85.4 µm²). STG and CMG FB+ neurons were immunoreactive (IR) for tyrosine hydroxylase (TH) (66±10.1% and 52.7±8.2%, respectively), dopamine beta-hydroxylase (DβH) (62±6.2% and 52±6.2%, respectively), neuropeptide Y (NPY) (59±8.2% and 65.8±7.3%, respectively), calcitonin-gene-related peptide (CGRP) (24.1±3.3% and 22.1±3.3%, respectively), substance P (SP) (21.6±2.4% and 37.7±7.5%, respectively), vasoactive intestinal polypeptide (VIP) (18.9±2.3% and 35.4±4.4%, respectively), neuronal nitric oxide synthase (nNOS) (15.3±2% and 32.9±7.7%, respectively), vesicular acetylcholine transporter (VAChT) (15±2% and 34.7±4.5%, respectively), leuenkephalin (LENK) (14.3±7.1% and 25.9±8.9%, respectively), and somatostatin (SOM) (12.4±3% and 31.8±7.3%, respectively). UBT-projecting neurons were also surrounded by VAChT-, CGRP-, LENK-, and nNOSIR fibers. The possible role of these neurons and fibers in the neural pathways of the UBT is discussed.

Higher resistance of porcine trigeminal ganglion neurons towards pseudorabies virus-induced cell death compared with other porcine cell types in vitro

Trigeminal ganglion (TG) neurons are important target cells for many alphaherpesviruses, constituting major sites for latency/reactivation events. Here, the in vitro kinetics of productive infection of the swine alphaherpesvirus pseudorabies virus (PRV) and resulting cell death in primary porcine TG neurons were determined, and these were compared with similar kinetics in many other porcine cell types. Confocal microscopy showed that all TG neurons expressed late genes such as viral glycoproteins, and that these glycoproteins were processed through the Golgi and reached the cell surface as in other cell types, albeit with a delay of +/-2-6 h. However, TG neurons were much more resistant towards PRV-induced cell death compared with all other porcine cell types tested (non-neuronal TG cells, superior cervical ganglion neurons, epithelial kidney cells, arterial endothelial cells, dermal fibroblasts and cells derived from a porcine swine kidney cell line). About half of the TG neurons survived up to 96 h post-inoculation (end of experiment), whereas all other cell types almost completely succumbed within 2 days post-inoculation. In addition, infection with a strongly pro-apoptotic PRV strain that misses the anti-apoptotic US3 protein did not lead to substantial apoptosis in TG neurons, even at 72 h post-inoculation. Thus, primary porcine TG neurons can be infected with PRV in vitro, and are remarkably more resistant to PRV-induced cell death compared with other porcine cell types, suggesting a cell type-specific resistance to alphaherpesvirus-induced cell death that may have important implications for different aspects of the virus life cycle, including latency/reactivation events.

Presence of cellular renin-angiotensin system in chromaffin cells of bovine adrenal medulla

The presence of a local renin-angiotensin system has been established in organs that serve as angiotensin targets. In this study, the expression of angiotensinogen mRNA and subcellular localization of renin, angiotensin-converting enzyme, and angiotensin II were investigated in bovine adrenal medullary cells in primary culture. By light microscopy, expression of angiotensinogen mRNA, immunoreactive renin, angiotensin-converting enzyme, and angiotensin II were readily detectable only in the chromaffin cells. The density distribution of renin and angiotensin II in sucrose gradients suggested a concentration in chromaffin granules, a localization directly confirmed by immunoelectron microscopy. Reverse transcriptase-polymerase chain reaction and sequencing confirmed the expression of angiotensinogen in bovine chromaffin cells and the adrenal medulla. In addition, in vitro autoradiography indicated that both angiotensin-converting enzyme and angiotensin type 1 receptors were present in the adrenal medulla. These results provide the first direct evidence that chromaffin cells in the adrenal medulla are not only the target for angiotensin but should also be considered as potential local angiotensin-generating and -storing cells.

Changes in the expression of alpha(2)-adrenergic receptor subtypes during maturation of neuronal cells from fetal pig superior cervical ganglia

The expression of presynaptic alpha(2)-adrenergic receptor (alpha(2)-AR) subtypes was investigated in cultured neurons from fetal pig superior cervical ganglion (SCG). Cells were incubated with chicken antibodies against alpha(2)A-, alpha(2)B- or alpha(2)C-AR subtypes either alone or together with antibodies against dopamine-beta-hydroxylase (DbetaH, a marker for adrenergic neurons) or against choline acetyl transferase (ChAT, a marker for cholinergic neurons). We found immunoreactivity for all three alpha(2)-AR subtypes in SCG-cells when cultured for 8-11 days. The relative expression of the alpha(2)A-subtype was approximately 1/3 of that of alpha(2)B- and alpha(2)C-AR. Co-localisation of all three alpha(2)-AR subtypes was observed in cells expressing DbetaH or ChAT. Increasing the potassium concentration in the culture medium increased the expression of DbetaH and decreased the expression of the alpha(2)A- and alpha(2)C-subtype without altering the expression of the alpha(2)B-subtype. Co-culture of neurons with pig splenocytes enhanced the expression of ChAT and decreased the expression of the alpha(2)B-subtype without altering the expression of alpha(2)A- and alpha(2)C-subtypes. Our results indicate that the three alpha(2)-receptor subtypes are expressed on both noradrenergic and cholinergic nerves. Induction of the noradrenergic phenotype favours the expression of the alpha(2)B-subtype over that of the alpha(2)A- and alpha(2)C-subtype. Conversely, enhancement of the cholinergic phenotype favours the expression of the alpha(2)A- and alpha(2)C-subtypes over that of the alpha(2)B-subtype. Our results suggest that the alpha(2)B-receptor is preferentially associated with noradrenergic nerve endings.

Secretory vesicle-specific antibodies in the confocal study of exo-endocytosis dynamics

The study of secretory vesicle dynamics is a continuing challenge. Classically it was studied using biochemical techniques, such as subcellular fractionation and immunoprecipitation, combined with time-consuming electron microscopy studies. The recent development of confocal microscopy, giving in-focus optical section images throughout the thickness of a fluorescently labeled sample, allows scientists to study the key events in the secretory cycle at the level of light microscopy. This study demonstrates the use of specific antibodies against marker proteins of two different secretory vesicles (synaptic vesicles and large dense-cored vesicles) to follow their exo-endocytosis dynamics in peripheral adrenergic neurons. Only in recent years has insight grown regarding the presence of both exocytosis pathways in the same neuron. Confocal microscopy is a suitable technique to study aspects of exocytosis, endocytosis, and intracellular sorting and as such improves our knowledge on the interaction between both secretory pathways.

Retrieved constituents of large dense-cored vesicles and synaptic vesicles intermix in stimulation-induced early endosomes of noradrenergic neurons

Two storage compartments in cultured noradrenergic neurons derived from the superior cervical ganglion from fetal pig have been defined using sucrose density gradient centrifugation and electron microscopy: (1) large dense-cored vesicles (LDV) contain noradrenaline and dopamine-beta-hydroxylase (DbetaH); (2) small electron-lucent vesicles contain acetylcholine and p38 and represent the noradrenergic small synaptic vesicles (SSV); no small dense-cored vesicles (SDV) could be detected. Our results demonstrate that internalized LDV membrane constituents are retrieved into early endosomes, as shown by the colocalization of retrieved DbetaH with the endosomal markers Rab5 and HRP in sucrose density gradients and on confocal microscopical images. Recycling of the SSV membranes via an endosomal intermediate is also confirmed in noradrenergic neurons. Finally, colocalization of retrieved DbetaH and retrieved p38 in stimulated neurons indicates that the two sets of constituents intermix. These data provide the first experimental evidence for a common early endosome in which SSV and LDV membrane constituents are internalized after exocytosis and imply that endosomal sorting is an important process for the generation of different secretory vesicles in the noradrenergic nerve terminal.