Biology subjects

Rouse, H.

Publications and source records attributed to Rouse, H..

3 recordsLinked to original sources

bioRxiv2026

Optic nerve innervation promotes Wnt/b-catenin pathway activity and progenitor cell proliferation in the zebrafish optic tectum

In the zebrafish visual system, accurate retinotopic mapping occurs throughout life as new neurons are generated and integrated into existing circuitry in both the retina and optic tectum (OT). To explore how OT development changes relative to innervation from the retina, we examined cell death and proliferation in genetic and surgical models that disrupt retinal innervation of the OT. Specifically, we compared lakritz (lak) mutants, which have no optic nerves due to a lesion in the atoh7 gene, with either wild-type or one-eyed fish generated through surgical eye removal. We observed elevated cell death, fewer proliferating progenitors, and fewer sox2+ OT neuroepithelial stem cells in lak mutant and denervated OT lobes. To examine whether light-mediated vision contributes to proliferation and survival in the optic tectum, we reared fish in constant darkness and then compared survival and proliferation of OT cells in innervated and non-innervated tecta. We found that OT cells were still more likely to survive and proliferate in the presence of optic nerve innervation even when fish were reared in the dark. To identify molecular pathways that could regulate OT growth, we examined the expression of known mitogens in the zebrafish optic tectum and found evidence that Wnt/{beta}-catenin pathway activity could promote innervation-dependent proliferation in lak mutant tecta. Expression of both wnt3a and the Wnt/{beta}-catenin target gene axin2, as detected by in situ hybridization and RT-qPCR, is decreased in non-innervated tectal lobes. Further supporting an innervation-dependent role for Wnt/{beta}-catenin pathway activation in the zebrafish OT, we found that lak mutants treated with a Wnt-pathway agonist, BIO, exhibited levels of OT cell proliferation that were indistinguishable from wild-type. Together these findings suggest that progenitor cells in the optic tectum produce Wnt3a in response to innervation by the optic nerve, providing new insight into how a vertebrate visual system coordinates growth across its sensory and recipient tissues.

Developmental Biology↗

bioRxiv2024

Metabolic remodelling in hiPSC-derived myofibres carrying the m.3243A>G mutation

Mutations in mitochondrial DNA cause severe multisystem disease, frequently associated with muscle weakness. The m.3243A>G mutation is the major cause of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke Like episodes (MELAS). Experimental models that recapitulate the disease phenotype in vitro for disease modelling or drug screening are very limited. We have therefore generated hiPSC-derived muscle fibres with variable heteroplasmic mtDNA mutation load without significantly affecting muscle differentiation potential. The cells are excitable and show physiological characteristics of muscle fibres and show well organised myofibrillar structure. In cells carrying the m.3243A>G, the mitochondrial membrane potential and oxygen consumption were reduced in relation to the mutant load. We have shown through proteomic, phosphoproteomic, and metabolomic analyses that the m.3243A>G mutation variably affects the cell phenotype in relation to the mutant load. This variation is reflected by an increase in the NADH/NAD+ ratio, which in turns influences key nutrient-sensing pathways in the myofibres. This model enables detailed study of the impact of the mutation on cellular bioenergetics and on muscle physiology with the potential to provide a platform for drug screening.

cell biology↗

bioRxiv2020

The GINS complex is required for the survival of rapidly proliferating retinal and tectal progenitor cells during zebrafish development

Efficient and accurate DNA replication is particularly critical in stem and progenitor cells for successful proliferation and survival. The replisome, an amalgam of protein complexes, is responsible for binding potential origins of replication, unwinding the double helix, and then synthesizing complimentary strands of DNA. According to current models, the initial steps of DNA unwinding and opening are facilitated by the CMG complex, which is composed of a GINS heterotetramer that connects Cdc45 with the mini-chromosome maintenance (Mcm) helicase. In this work, we provide evidence that in the absence of GINS function DNA replication is cell autonomously impaired, and we also show that gins1 and gins2 mutants exhibit elevated levels of apoptosis restricted to actively proliferating regions of the central nervous system (CNS). Intriguingly, our results also suggest that the rapid cell cycles during early embryonic development in zebrafish may not require the function of the GINS complex as neither Gins1 nor Gins2 seem to be present during these stages.

genetics↗