Biology subjects

French, C. R.

Publications and source records attributed to French, C. R..

3 recordsLinked to original sources

bioRxiv2023

CBD can be combined with additional cannabinoids for optimal seizure reduction and requires GPR55 for its anticonvulsant effects

BackgroundCannabis has demonstrated anticonvulsant properties, and cannabis-based medicines are approved to treat pediatric patients with severe pediatric epilepsies that are particularly refractive to approved anti-epileptic drugs (AEDs). About thirty percent of epileptic patients do not have satisfactory seizure management with AEDs and could potentially benefit from cannabis-based intervention. Here we report the use of single and combined cannabinoids to treat Pentylenetetrazol (PTZ) induced convulsions in a zebrafish model, their effect on gene expression, and a simple assay for assessing their uptake in zebrafish tissues. These data provide novel insights as to the potential of treating epilepsy with cannabinoids. MethodsZebrafish larvae were treated with cannabinoids and their seizures measured through an optimized behaviour tracking method. Cannabinoid uptake was measured with a novel HPLC-UV method. Gene expression changes were assessed using quantitative PCR (qPCR), and chemical inhibitors of potential cannabinoid receptors were used to block activity. ResultsTreatment with cannabinol (CBN), cannabichromene (CBC) and cannabigerol (CBG) decreased seizure intensity at lower doses than CBD when accounting for the amount of cannabinoid recovered from exposed larvae. {Delta}9-tetrahydrocannabinol ({Delta}9-THC), {Delta}8-tetrahydrocannabinol ({Delta}8-THC) were effective at higher doses. Synergistic effects were observed between CBD and other cannabinoids such as {Delta}9-THC, {Delta}8-THC, and CBG. The reduction of PTZ induced seizures via CBD is partially mediated by the G-protein coupled receptor GPR55, as pharmacological inhibition of the receptor reduced the therapeutic action of CBD. Changes in expression of endocannabinoid system (napepld, gde1, faah, ptgs2a) and neural (fosab, pyya) genes in response to phytocannabinoid treatment were observed and highlight novel mechanisms of phytocannabinoid action. ConclusionsCBD can be combined with additional cannabinoids for optimal reduction of seizure activity and requires the activity of GPR55. Changes in fosab regulation of gene expression and endocannabinoid signalling may influence the anticonvulsant effects of cannabis, however further investigation is required.

pharmacology and toxicology↗

bioRxiv2020

Pleiotropy in FOXC1-attributable phenotypes involves altered ciliation and cilia-dependent signaling

Alterations to cilia are responsible for a wide range of severe disease; however, understanding of the transcriptional control of ciliogenesis remains incomplete. We evaluated whether ciliary dysfunction contributed to the pleiotropic phenotypes caused by the Forkhead transcription factor FOXC1. Here, we show that patients with FOXC1-attributable Axenfeld-Rieger Syndrome (ARS) have a prevalence of ciliopathy-associated phenotypes comparable to syndromic ciliopathies. We demonstrate that altering the level of Foxc1, via shRNA mediated inhibition and mRNA overexpression, modifies cilia length in vitro. These structural changes were associated with substantially perturbed cilia-dependent signaling [Hedgehog (Hh) and PDGFR] and the altered ciliary compartmentalization of a major Hh pathway transcription factor, Gli2. Analyses of two Foxc1 murine mutant strains demonstrated altered axonemal length in the choroid plexus with the increased expression of an essential regulator of multi-ciliation, Foxj1. The novel complexity revealed in ciliation of the choroid plexus indicates a partitioning of function between these Forkhead transcription factors. Collectively, these results support a contribution from ciliary dysfunction to some FOXC1-induced phenotypes.

genetics↗

bioRxiv2020

The Axenfeld-Rieger syndrome gene FOXC1 contributes to left-right patterning

Normal body situs requires precise spatiotemporal expression of the Nodal-Lefty-Pitx2 cascade in the lateral plate mesoderm. The ultimate output of this patterning is establishment of the left-right axis, which provides vital cues for correct organ formation and function. Mutations, deletions and duplications in PITX2 and FOXC1 lead to the rare genetic disease Axenfeld-Rieger syndrome (ARS). While situs defects are not a recognised feature of ARS, partial penetrance of cardiac septal defects and valve incompetence is observed; both of these congenital heart defects (CHDs) also occur following disruption of left-right patterning. Here we investigated whether foxc1 genes have a critical role in specifying organ situs. We demonstrate that CRISPR/Cas9 generated mutants for the zebrafish paralogs foxc1a and foxc1b recapitulate ARS phenotypes including craniofacial dysmorphism, hydrocephalus and intracranial haemorrhage. Furthermore, foxc1a-/-; foxc1b-/- mutant animals display cardiac and gut situs defects. Modelling FOXC1 duplication by transient mRNA overexpression revealed that increased foxc1 dosage also results in organ situs defects. Analysis of known left-right patterning genes revealed a loss in expression of the NODAL antagonist lefty2 in the lateral plate mesoderm. Consistently, LEFTY2 mutations are known to cause human cardiac situs defects. Our data reveal a novel role for the forkhead-box transcription factor foxc1 in patterning of the left-right axis, and provide a plausible mechanism for the incidence of congenital heart defects in Axenfeld-Rieger syndrome patients. Author SummaryThis manuscript investigates the functional consequences of abrogating the activity of Foxc1 (Forkhead Box C1). We demonstrate that loss of zebrafish foxc1a and foxc1b results in phenotypes that resemble human patients with deletions in the FOXC1 locus. Notably, such phenotypes include alterations to the morphology of the heart. Investigations into the mechanisms underlying this phenotype led to the discovery that Foxc1 functions as a regulator of left-right patterning. Most components of left-right specification function normally in foxc1a/b mutants, but there is a pronounced loss of lefty2, a known inhibitor of Nodal signaling. This supports a model in which Foxc1 regulates situs of the heart via the regulation of Lefty2.

genetics↗