Suchergebnisse

During primary infection, herpes simplex virus 2 (HSV-2) replicates in epithelial cells and enters neurites to infect neurons of the peripheral nervous system. Growth factors and attractive and repulsive directional cues influence neurite outgrowth and neuronal survival. We hypothesized that HSV-2 modulates the activity of such cues to increase neurite outgrowth. To test this hypothesis, we exposed sensory neurons to nerve growth factor (NGF) and mock- or HSV-2-infected HEK- 293T cells, since they express repellents of neurite outgrowth. We show that HEK- 293T cells secrete factors that inhibit neurite outgrowth, while infection with HSV-2 strains MS and 333 reduces this repelling phenotype, increasing neurite numbers. The HSV-2-mediated restoration of neurite outgrowth required the activity of NGF. In the absence of infection, however, NGF did not overcome the repulsion mediated by HEK-293T cells. We previously showed that recombinant, soluble glycoprotein G of HSV-2 (rSgG2) binds and enhances NGF activity, increasing neurite outgrowth. However, the effect of gG2 during infection has not been investigated. Therefore, we addressed whether gG2 contributes to overcoming neurite outgrowth repulsion. To do so, we generated viruses lacking gG2 expression and complemented them by exogenous expression of gG2. Overall, our results suggest that HSV-2 infection of nonneuronal cells reduces their repelling effect on neurite outgrowth in an NGF-dependent manner. gG2 contributed to this phenotype, but it was not the only factor. The enhanced neurite outgrowth may facilitate HSV-2 spread from epithelial cells into neurons expressing NGF receptors and increase HSV-2-mediated pathogenesis. ; Deutsche Forschungsgemeinschaft (DFG [German Research Foundation]) grant SFB 900/3-158989968 to A.V.-B. (TPB9) and B.S. (TPC2) (https://www.mh-hannover.de/sfb900.html) and by the DFG under Germany's Excellence Strategy (grant EXC 2155, project number 390874280, to B.S. and A.V.-B. and Cluster of Excellence REBIRTH to B.S. [Unit 8.1]). A.V.-B. received a Marie Curie Career Integration Grant fellowship (European Union Horizon 2020 program FP7-PEOPLE-2013-CIG [INMA] project number 631792), and K.A.K. was funded by grant SFB 900/3 from the DFG. S.S. was funded by the Niedersachsen-Research Network on Neuroinfectiology (N-RENNT) of the Ministry of Science and Culture of Lower Saxony (to B.S. and A.V.-B.; http://www.tiho-hannover.de/forschung/n-rennt/). J.S.C. was funded by the Free and Hanseatic City of Hamburg, Germany (grant Graduiertenkolleg DELIGRAH LFFGK06). A.D. was funded by core funding from the Hannover Medical School. The laboratory of A.A. was funded by the Spanish Ministry of Economy and Competitiveness and the European Union (European Regional Development Funds [FEDER] grant SAF2015-67485-R), and A.D.L.-M. was funded by a Ph.D. fellowship from the Ministerio de Educacion, Cultura y Deporte

Somatosensory low threshold mechanoreceptors (LTMRs) sense innocuous mechanical forces, largely through specialized axon termini termed sensory nerve endings, where the mechanotransduction process initiates upon activation of mechanotransducers. In humans, a subset of sensory nerve endings is enlarged, forming bulb-like expansions, termed bulbous nerve endings. There is no in vitro human model to study these neuronal endings. Piezo2 is the main mechanotransducer found in LTMRs. Recent evidence shows that Piezo1, the other mechanotransducer considered absent in dorsal root ganglia (DRG), is expressed at low level in somatosensory neurons. We established a differentiation protocol to generate, from iPSC-derived neuronal precursor cells, human LTMR recapitulating bulbous sensory nerve endings and heterogeneous expression of Piezo1 and Piezo2. The derived neurons express LTMR-specific genes, convert mechanical stimuli into electrical signals and have specialized axon termini that morphologically resemble bulbous nerve endings. Piezo2 is concentrated within these enlarged axon termini. Some derived neurons express low level Piezo1, and a subset co-express both channels. Thus, we generated a unique, iPSCs-derived human model that can be used to investigate the physiology of bulbous sensory nerve endings, and the role of Piezo1 and 2 during mechanosensation. ; This work was supported by N-RENNT of the Ministry of Science and Culture of Lower Saxony to A.V.B., by a Marie Curie Career Integration Grant to A.V.B. (FP7-PEOPLE-2013-CIG, project number 631792, acronym INMA), by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC 2155 "RESIST" – Project ID 39087428, by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - SFB-900 – 158989968 to R.F. (B1) and A.V.B. (B9), and by a Spanish Government project to A.G. (PID2019-108194RB-I00). ; Peer reviewed