Pax6 limits the competence of developing cerebral cortical cells to respond to inductive intercellular signals

A stochastic model for neural progenitor dynamics in the mouse cerebral cortex

We have designed a stochastic model of embryonic neurogenesis in the mouse cerebral cortex, using the formalism of compound Poisson processes. The model accounts for the dynamics of different progenitor cell types and neurons. The expectation and variance of the cell number of each type are derived analytically and illustrated through numerical simulations. The effects of stochastic transition rates between cell types, and stochastic duration of the cell division cycle have been investigated sequentially. The model does not only predict the number of neurons, but also their spatial distribution into deeper and upper cortical layers. The model outputs are consistent with experimental data providing the number of neurons and intermediate progenitors according to embryonic age in control and mutant situations.

Transcriptional regulation in the development and dysfunction of neocortical projection neurons

Glutamatergic projection neurons generate sophisticated excitatory circuits to integrate and transmit information among different cortical areas, and between the neocortex and other regions of the brain and spinal cord. Appropriate development of cortical projection neurons is regulated by certain essential events such as neural fate determination, proliferation, specification, differentiation, migration, survival, axonogenesis, and synaptogenesis. These processes are precisely regulated in a tempo-spatial manner by intrinsic factors, extrinsic signals, and neural activities. The generation of correct subtypes and precise connections of projection neurons is imperative not only to support the basic cortical functions (such as sensory information integration, motor coordination, and cognition) but also to prevent the onset and progression of neurodevelopmental disorders (such as intellectual disability, autism spectrum disorders, anxiety, and depression). This review mainly focuses on the recent progress of transcriptional regulations on the development and diversity of neocortical projection neurons and the clinical relevance of the failure of transcriptional modulations.

Potential of Nano-Engineered Stem Cells in the Treatment of Multiple Sclerosis: A Comprehensive Review

Multiple sclerosis (MS) is a chronic and degrading autoimmune disorder mainly targeting the central nervous system, leading to progressive neurodegeneration, demyelination, and axonal damage. Current treatment options for MS are limited in efficacy, generally linked to adverse side effects, and do not offer a cure. Stem cell therapies have emerged as a promising therapeutic strategy for MS, potentially promoting remyelination, exerting immunomodulatory effects and protecting against neurodegeneration. Therefore, this review article focussed on the potential of nano-engineering in stem cells as a therapeutic approach for MS, focusing on the synergistic effects of combining stem cell biology with nanotechnology to stimulate the proliferation of oligodendrocytes (OLs) from neural stem cells and OL precursor cells, by manipulating neural signalling pathways-PDGF, BMP, Wnt, Notch and their essential genes such as Sox, bHLH, Nkx. Here we discuss the pathophysiology of MS, the use of various types of stem cells in MS treatment and their mechanisms of action. In the context of nanotechnology, we present an overview of its applications in the medical and research field and discuss different methods and materials used to nano-engineer stem cells, including surface modification, biomaterials and scaffolds, and nanoparticle-based delivery systems. We further elaborate on nano-engineered stem cell techniques, such as nano script, nano-exosome hybrid, nano-topography and their potentials in MS. The article also highlights enhanced homing, engraftment, and survival of nano-engineered stem cells, targeted and controlled release of therapeutic agents, and immunomodulatory and tissue repair effects with their challenges and limitations. This visual illustration depicts the process of utilizing nano-engineering in stem cells and exosomes for the purpose of delivering more accurate and improved treatments for Multiple Sclerosis (MS). This approach targets specifically the creation of oligodendrocytes, the breakdown of which is the primary pathological factor in MS.

Bayesian cluster analysis

Bayesian cluster analysis offers substantial benefits over algorithmic approaches by providing not only point estimates but also uncertainty in the clustering structure and patterns within each cluster. An overview of Bayesian cluster analysis is provided, including both model-based and loss-based approaches, along with a discussion on the importance of the kernel or loss selected and prior specification. Advantages are demonstrated in an application to cluster cells and discover latent cell types in single-cell RNA sequencing data to study embryonic cellular development. Lastly, we focus on the ongoing debate between finite and infinite mixtures in a model-based approach and robustness to model misspecification. While much of the debate and asymptotic theory focuses on the marginal posterior of the number of clusters, we empirically show that quite a different behaviour is obtained when estimating the full clustering structure. This article is part of the theme issue 'Bayesian inference: challenges, perspectives, and prospects'.

The people behind the papers - Rana Fetit and David Price

16p11.2 microdeletions are genetically associated with autism spectrum disorder (ASD), but the links to the various patient phenotypes are not well understood. In a new paper in Development, Rana Fetit and colleagues use ventral organoids derived from induced pluripotent stem cells to dissect the effect of 16p11.2 microdeletions on interneuron development. We caught up with corresponding author Rana Fetit and group leader David Price to find out more about their research.

Pax6 mutant cerebral organoids partially recapitulate phenotypes of Pax6 mutant mouse strains

Cerebral organoids show great promise as tools to unravel the complex mechanisms by which the mammalian brain develops during embryogenesis. We generated mouse cerebral organoids harbouring constitutive or conditional mutations in Pax6, which encodes a transcription factor with multiple important roles in brain development. By comparing the phenotypes of mutant organoids with the well-described phenotypes of Pax6 mutant mouse embryos, we evaluated the extent to which cerebral organoids reproduce phenotypes previously described in vivo. Organoids lacking Pax6 showed multiple phenotypes associated with its activity in mice, including precocious neural differentiation, altered cell cycle and an increase in abventricular mitoses. Neural progenitors in both Pax6 mutant and wild type control organoids cycled more slowly than their in vivo counterparts, but nonetheless we were able to identify clear changes to cell cycle attributable to the absence of Pax6. Our findings support the value of cerebral organoids as tools to explore mechanisms of brain development, complementing the use of mouse models.

Developmental disruption and restoration of brain synaptome architecture in the murine Pax6 neurodevelopmental disease model

Neurodevelopmental disorders of genetic origin delay the acquisition of normal abilities and cause disabling phenotypes. Nevertheless, spontaneous attenuation and even complete amelioration of symptoms in early childhood and adolescence can occur in many disorders, suggesting that brain circuits possess an intrinsic capacity to overcome the deficits arising from some germline mutations. We examined the molecular composition of almost a trillion excitatory synapses on a brain-wide scale between birth and adulthood in mice carrying a mutation in the homeobox transcription factor Pax6, a neurodevelopmental disorder model. Pax6 haploinsufficiency had no impact on total synapse number at any age. By contrast, the molecular composition of excitatory synapses, the postnatal expansion of synapse diversity and the acquisition of normal synaptome architecture were delayed in all brain regions, interfering with networks and electrophysiological simulations of cognitive functions. Specific excitatory synapse types and subtypes were affected in two key developmental age-windows. These phenotypes were reversed within 2-3 weeks of onset, restoring synapse diversity and synaptome architecture to the normal developmental trajectory. Synapse subtypes with rapid protein turnover mediated the synaptome remodeling. This brain-wide capacity for remodeling of synapse molecular composition to recover and maintain the developmental trajectory of synaptome architecture may help confer resilience to neurodevelopmental genetic disorders.