A Functional Dissection of the mRNA and Locally Synthesized Protein Population in Neuronal Dendrites and Axons.

Neurons are characterized by a complex morphology that enables the generation of subcellular compartments with unique biochemical and biophysical properties, such as dendrites, axons, and synapses. To sustain these different compartments and carry a wide array of elaborate operations, neurons express a diverse repertoire of gene products. Extensive regulation at both the messenger RNA (mRNA) and protein levels allows for the differentiation of subcellular compartments as well as numerous forms of plasticity in response to variable stimuli. Among the multiple mechanisms that control cellular functions, mRNA translation is manipulated by neurons to regulate where and when a protein emerges. Interestingly, transcriptomic and translatomic profiles of both dendrites and axons have revealed that the mRNA population only partially predicts the local protein population and that this relation significantly varies between different gene groups. Here, we describe the space that local translation occupies within the large molecular and regulatory complexity of neurons, in contrast to other modes of regulation. We then discuss the specialized organization of mRNAs within different neuronal compartments, as revealed by profiles of the local transcriptome. Finally, we discuss the features and functional implications of both locally correlated-and anticorrelated-mRNA-protein relations both under baseline conditions and during synaptic plasticity.

[Morphological markers of pathophysiological changes in the neuronal processes in the acute post-traumatic period of diffuse axonal injury]. / Morfologicheskie markery patofiziologicheskikh izmenenii otrostkov neironov v ostrom posttravmaticheskom periode diffuznogo aksonal'nogo povrezhdeniya mozga.

The purpose of the study was to establish morphological markers of pathophysiological changes in the neuronal processes of in the acute (up to 36 hours) post-traumatic period of diffuse axonal injury (DAI) for the purposes of expert practice. Histological examination of the body of corpus callosum of the corpses of 66 persons dead from DAI and of 25 persons dead from various non-violent and violent causes, excluding head trauma, was performed (control group). Morphological markers of specific pathophysiological changes in the neuronal process were established by light microscopy with the use of immunohistochemical examination in acute period DAI. Uneven contours of the processes suggested displacement of cytoskeletal elements, areas of vacuolization of the cytoplasm of the processes suggested violation of intracellular transport caused by a change of permeability with preserved integrity of the process shell without mechanical separation of the process, uneven thickness (3.9 ± 1.6 µm) of the processes, varicose and cone-shaped thickening of them was a manifestation of focal edema of the neuronal process and compression of the cytoskeleton as a result of ion-enzymatic disorders, uneven coloration, areas of fragmentary compaction of neurofilaments indicated the zones of deformation and compression of the cytoskeleton, zones of granular-lumpy decay and fibrillolysis of neurofilaments indicated destruction of the cytoskeleton. Changes in the neuronal processes are a manifestation of a polyethological general pathological process and are not a differential diagnostic criterion of DAI.

[Axotomy in the postmortem diagnosis of diffuse axonal brain injury]. / Aksotomiya v posmertnoi diagnostike diffuznogo aksonal'nogo povrezhdeniya golovnogo mozga.

The results of the study of the significance of axotomy in the postmortem diagnosis of diffuse axonal brain damage are presented. In the corpus callosum, two main types of changes in the processes of neurons were found: damage to the processes without mechanical rupture and axotomy. The revealed polymorphism of damage to the processes of neurons indicates the heterogeneity and staging of pathological processes caused both by the trauma itself and by developing reactive post-traumatic changes. Severe damage to the processes is secondary and not earlier than 2 days after the injury lead to axotomy, the morphological manifestation of which is retraction balls with a diameter of 15.5±6.33 µm, detected by staining with hematoxylin and eosin. Research results indicate that axotomy should not be differentiated into primary and secondary.

The Effect of Botulinum Neurotoxin Serotype a Heavy Chain on the Growth Related Proteins and Neurite Outgrowth after Spinal Cord Injury in Rats.

(1) Background: The botulinum toxin A (BoNT-A) heavy chain (HC) can stimulate the growth of primary motor neurites. (2) Methods: A recombinant BoNT/A HC was injected locally plus interval intrathecal catheter of BoNT/A HC to rats with ipsilateral semi-dissociated lumbar spinal cord injuries (SCIs). First, 2D gel with a silver nitrate stain was applied to detect the general pattern of protein expression. Growth associated protein 43 (GAP-43) and superior cervical ganglion 10 (SCG10) were chosen to represent the altered proteins, based on their molecular weight and pI, and were used to further detect their expression. Meanwhile, the neuronal processes were measured. The measurements of thermal hyperalgesia and grasp power at the ipsilateral hindlimb were used to evaluate spinal sensory and motor function, respectively. (3) Results: The local injection of BoNT/A HC followed by its intrathecal catheter intervally altered the spinal protein expression pattern after an SCI; protein expression was similar to normal levels or displayed a remarkable increase. The changes in the expression and distribution of phosphorylated growth associated protein 43(p-GAP 43) and superior cervical ganglion 10 (SCG 10) indicated that the administration of BoNT/A HC to the SCI significantly amplified the expression of p-GAP43 and SCG10 (p < 0.05). Meanwhile, the positive immunofluorescent staining for both p-GAP43 and SCG10 was mainly present near the rostral aspect of the injury, both in the cytoplasm and the neuronal processes. Moreover, the outgrowth of neurites was stimulated by the BoNT/A HC treatment; this was evident from the increase in neurite length, number of branches and the percentage of cells with neuronal processes. The results from the spinal function tests suggested that the BoNT/A HC did not affect sensation, but had a large role in improving the ipsilateral hindlimb grasp power (p < 0.05). (4) Conclusions: The local injection with the intermittent intrathecal administration of BoNT/A heavy chain to rats with SCI increased the local expression of GAP-43 and SCG 10, which might be affiliated with the regeneration of neuronal processes surrounding the injury, and might also be favorable to the relief of spinal motor dysfunction.

Examination of the transition of cultured neuronal cells from submerged to exposed using an environmental scanning electron microscope (ESEM).

Relatively few studies of fully hydrated live or fixed cultured animal cells viewed by environmental scanning electron microscopy (ESEM) have been published. In some cases there may have been some drying out of the cells. In this study the interface between water and cells is imaged as water is carefully evaporated to expose cells. Technical difficulties associated with the process, including inadvertent rewetting of cells are described. Suggestions are made for optimising operating parameters for viewing fully hydrated cultured cells by ESEM. The prospects for viewing live cultured cells are discussed.