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Retina ganglion cell (RGC) axons grow along a stereotyped pathway undergoing coordinated rounds of fasciculation and defasciculation, which are critical to establishing proper eye– brain connections. How this coordination is achieved is poorly understood, but shedding of guidance cues by metalloproteinases is emerging as a relevant mechanism. Secreted Frizzled Related Proteins (Sfrps) are multifunctional proteins, which, among others, reorient RGC growth cones by regulating intracellular second messengers, and interact with Tolloid and ADAM metalloproteinases, thereby repressing their activity. Here, we show that the combination of these two functions well explain the axon guidance phenotype observed in Sfrp1 and Sfrp2 single and compound mouse mutant embryos, in whichRGCaxons make subtle but significant mistakes during their intraretinal growth and inappropriately defasciculate along their pathway. The distribution of Sfrp1 and Sfrp2 in the eye is consistent with the idea that Sfrp1/2 normally constrain axon growth into the fiber layer and the optic disc. Disheveled axon growth instead seems linked to Sfrp-mediated modulation of metalloproteinase activity. Indeed, retinal explants from embryos with different Sfrp-null alleles or explants overexpressing ADAM10 extend axons with a disheveled appearance, which is reverted by the addition of Sfrp1 or an ADAM10-specific inhibitor. This mode of growth is associated with an abnormal proteolytic processing of L1 and N-cadherin, two ADAM10 substrates previously implicated in axon guidance.Wethus propose that Sfrps contribute to coordinate visual axon growth with a dual mechanism: by directly signaling at the growth cone and by regulating the processing of other relevant cues. ; This work was supported by the Spanish MINECO (Grants BFU2010-16031 and BFU2013-43213-P), Comunidad Autonoma de Madrid (Grant S2010/BMD-2315) Cost Action BM1001 Brain ECM in Health and Disease, an institutional grant from the Fundación Ramón Areces and Centro de Investigación Biomédica en Red de Enfermedades Raras (P.B.). F.N.-L. and M.J.C. were supported by a FPU and FPI fellowship from the Spanish Government, respectively. ; Peer Reviewed

A prevalent developmental mechanism for the assignment of cell identities is the production of spatiotemporal concentration gradients of extracellular signaling molecules that are interpreted by the responding cells. One of such signaling systems is the Shh gradient that controls neuronal subtype identity in the ventral spinal cord. Using loss and gain of function approaches in chick and mouse embryos, we show here that the fibroblast growth factor (FGF) signaling pathway is required to restrict the domains of ventral gene expression as neuroepithelial cells become exposed to Shh during caudal extension of the embryo. FGF signaling activates the expression of the Shh receptor and negative pathway regulator Patched 2 (Ptch2) and therefore can enhance a negative feedback loop that restrains the activity of the pathway. Thus, we identify one of the mechanisms by which FGF signaling acts as a modulator of the onset of Shh signaling activity in the context of coordination of ventral patterning and caudal axis extension. VC 2015Wiley Periodicals, Inc. Develop Neurobiol 76: 956–971, 2016 ; Spanish government; contract grant numbers: BFU2014-57494-R, BFU2011-29490, BFU2010-15665, BFU2005-02972 (to A. M. and R. D.) and BFU2007-61774, BFU2010-16031-P (to P. B.). ; Peer Reviewed

The earliest known determinants of retinal nasotemporal identity are the transcriptional regulators Foxg1, which is expressed in the prospective nasal optic vesicle, and Foxd1, which is expressed in the prospective temporal optic vesicle. Previous work has shown that, in zebrafish, Fgf signals from the dorsal forebrain and olfactory primordia are required to specify nasal identity in the dorsal, prospective nasal, optic vesicle. Here, we show that Hh signalling from the ventral forebrain is required for specification of temporal identity in the ventral optic vesicle and is sufficient to induce temporal character when activated in the prospective nasal retina. Consequently, the evaginating optic vesicles become partitioned into prospective nasal and temporal domains by the opposing actions of Fgfs and Shh emanating from dorsal and ventral domains of the forebrain primordium. In absence of Fgf activity, foxd1 expression is established irrespective of levels of Hh signalling, indicating that the role of Shh in promoting foxd1 expression is only required in the presence of Fgf activity. Once the spatially complementary expression of foxd1 and foxg1 is established, the boundary between expression domains is maintained by mutual repression between Foxd1 and Foxg1 ; the European Commission [CIG321788 to F.C.]; the Comunidad Autonoma de Madrid (CAM) [S2010/BMD-2315 to P.B.]; the Deutsche Forschungsgemeinschaft [SFB655-A3 to P.B.]; and the European Union (Zf-Health) [HEALTH-F4-2010-242048 to M.B and S.W.W.]. An institutional grant from the Fundación Ramón Areces ; Peer Reviewed

Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.phrs.2020.104724. ; No adequate treatment is available for painful urinary bladder disorders such as interstitial cystitis/bladder pain syndrome, and the identification of new urological therapeutic targets is an unmet need. The sigma-1 receptor (σ1-R) modulates somatic pain, but its role in painful urological disorders is unexplored. The urothelium expresses many receptors typical of primary sensory neurons (e.g. TRPV1, TRPA1 and P2X3) and high levels of σ1- R have been found in these neurons; we therefore hypothesized that σ1-R may also be expressed in the urothelium and may have functional relevance in this tissue. With western blotting and immunohistochemical methods, we detected σ1-R in the urinary bladder in wild-type (WT) but not in σ1-R-knockout (σ1-KO) mice. Interestingly, σ1-R was located in the bladder urothelium not only in mouse, but also in human bladder sections. The severity of histopathological (edema, hemorrhage and urothelial desquamation) and biochemical alterations (enhanced myeloperoxidase activity and phosphorylation of extracellular regulated kinases 1/2 [pERK1/2]) that characterize cyclophosphamide-induced cystitis was lower in σ1-KO than in WT mice. Moreover, cyclophosphamide-induced pain behaviors and referred mechanical hyperalgesia were dose-dependently reduced by σ1-R antagonists (BD-1063, NE-100 and S1RA) in WT but not in σ1-KO mice. In contrast, the analgesic effect of morphine was greater in σ1-KO than in WT mice. Together these findings suggest that σ1-R plays a functional role in the mechanisms underlying cyclophosphamide-induced cystitis, and modulates morphine analgesia against urological pain. Therefore, σ1-R may represent a new drug target for urinary bladder disorders. ; Spanish Ministry of Economy and Competitiveness (MINECO) SAF2016-80540-R ; European Regional Development Funds (ERDF), Junta de Andalucia grant CTS 109 ; Esteve Pharmaceuticals ; Innovative Medicines Initiative 2 Joint Undertaking 777500 ; European Union's Horizon 2020 research and innovation programme ; EFPIA