Biology subjects

Florio, M.

Publications and source records attributed to Florio, M..

5 recordsLinked to original sources

bioRxiv2021

Developmental HCN channelopathy results in decreased neural progenitor proliferation and microcephaly in mice

The development of the cerebral cortex relies on the controlled division of neural stem and progenitor cells. The requirement for precise spatiotemporal control of proliferation and cell fate places a high demand on the cell division machinery, and defective cell division can cause microcephaly and other brain malformations. Cell-extrinsic and intrinsic factors govern the capacity of cortical progenitors to produce large numbers of neurons and glia within a short developmental time window. In particular, ion channels shape the intrinsic biophysical properties of precursor cells and neurons and control their membrane potential throughout the cell cycle. We found that hyperpolarization-activated cyclic nucleotide-gated cation (HCN)-channel subunits are expressed in mouse, rat, and human neural progenitors. Loss of HCN-channel function in rat neural stem cells impaired their proliferation by affecting the cell-cycle progression, causing G1 accumulation and dysregulation of genes associated with human microcephaly. Transgene-mediated, dominant-negative loss of HCN-channel function in the embryonic mouse telencephalon resulted in pronounced microcephaly. Together, our findings suggest a novel role for HCN-channel subunits as a part of a general mechanism influencing cortical development in mammals. Significance StatementImpaired cell cycle regulation of neural stem and progenitor cells can affect cortical development and cause microcephaly. During cell cycle progression, the cellular membrane potential changes through the activity of ion channels and tends to be more depolarized in proliferating cells. HCN channels, which mediate a depolarizing current in neurons and cardiac cells, are linked to neurodevelopmental diseases, also contribute to the control of cell-cycle progression and proliferation of neuronal precursor cells. In this study, HCN-channel deficiency during embryonic and fetal brain development resulted in marked microcephaly of mice designed to be deficient in HCN-channel function in dorsal forebrain progenitors. The findings suggest that HCN-channel subunits are part of a general mechanism influencing cortical development in mammals.

neuroscience↗

bioRxiv2020

Role for the Na+/K+ ATPase α 3 subunit in folding and lamination of the human neocortex

Osmotic equilibrium and membrane potential in animal cells depend on concentration gradients of sodium (Na+) and potassium (K+) ions across the plasma membrane, a function that is catalyzed by the Na,K-ATPase alpha subunit. In vertebrates, four paralogous genes, ATP1A1-4, encode distinct alpha subunit isoforms (a1-a4), three of which (a1, a2, a3) are expressed in the brain, and two (a1, a3) predominantly in neurons. The a3 isoform, encoded by ATP1A3, is critical to neuronal physiology, and a growing spectrum of neurological diseases are associated with ATP1A3 pathogenic variants, with ages of onset ranging from early childhood to adulthood. Here, we describe ATP1A3 variants encoding dysfunctional a3 subunits in children affected by polymicrogyria, a developmental malformation of the cerebral cortex characterized by abnormal folding and laminar organization. To gain cell-biological insights into the spatiotemporal dynamics of prenatal ATP1A3 expression, we established a transcriptional atlas of ATP1A3 expression during cortical development using mRNA in situ hybridization and transcriptomic profiling of ~125,000 individual cells with single-cell RNA sequencing (Drop-Seq) from various areas of the midgestational human neocortex. We find that fetal expression of ATP1A3 is restricted to a subset of excitatory neurons carrying transcriptional signatures of neuronal activity and maturation characteristic of the developing subplate. Furthermore, by performing Drop-Seq on ~52,000 nuclei from four different areas of an infant human neocortex, we show that ATP1A3 expression persists throughout early postnatal development, not only within excitatory neurons across all cortical layers, but also and more predominantly in inhibitory neurons, with specific enrichment in fast-spiking basket cells. In addition, we show that ATP1A3 expression, both in fetal and postnatal neurons, tends to be higher in frontal cortical areas than in occipital areas, in a pattern consistent with the rostro-caudal maturation gradient of the human neocortex. Finally, we discover distinct co-expression patterns linking catalytic subunit isoforms (ATP1A1,2,3) and auxiliary isoforms (ATP1B1,2,3), suggesting the ATPase pump may form non-redundant, cell-type specific -{beta} combinations. Together, the importance of the developmental phenotypes and dynamic expression patterns of ATP1A3 point to a key role for a3 in the development and function of human cortex.

neuroscience↗

bioRxiv2019

Innovations in Primate Interneuron Repertoire

Primates and rodents, which descended from a common ancestor more than 90 million years ago, exhibit profound differences in behavior and cognitive capacity. Modifications, specializations, and innovations to brain cell types may have occurred along each lineage. We used Drop-seq to profile RNA expression in more than 184,000 individual telencephalic interneurons from humans, macaques, marmosets, and mice. Conserved interneuron types varied significantly in abundance and RNA expression between mice and primates, but varied much more modestly among primates. In adult primates, the expression patterns of dozens of genes exhibited spatial expression gradients among neocortical interneurons, suggesting that adult neocortical interneurons are imprinted by their local cortical context. In addition, we found that an interneuron type previously associated with the mouse hippocampus--the \"ivy cell\", which has neurogliaform characteristics--has become abundant across the neocortex of humans, macaques, and marmosets. The most striking innovation was subcortical: we identified an abundant striatal interneuron type in primates that had no molecularly homologous cell population in mouse striatum, cortex, thalamus, or hippocampus. These interneurons, which expressed a unique combination of transcription factors, receptors, and neuropeptides, including the neuropeptide TAC3, constituted almost 30% of striatal interneurons in marmosets and humans. Understanding how gene and cell-type attributes changed or persisted over the evolutionary divergence of primates and rodents will guide the choice of models for human brain disorders and mutations and help to identify the cellular substrates of expanded cognition in humans and other primates.

neuroscience↗

bioRxiv2019

Extracellular matrix-inducing Sox9 orchestrates basal progenitor proliferation and gliogenesis in developing neocortex

Neocortex expansion is largely based on the proliferative capacity of basal progenitors (BPs), which is increased by extracellular matrix (ECM) components via integrin signaling. Here we show that Sox9 drives expression of ECM components and that laminin 211 increases BP proliferation in embryonic mouse neocortex. Examination of Sox9 expression reveals that Sox9 is expressed in BPs of developing ferret and human, but not mouse neocortex. Functional studies by conditional Sox9 expression in the mouse BP lineage demonstrate increased BP proliferation, reduced Tbr2 and induction of Olig2 expression, indicative of premature gliogenesis. Conditional Sox9 expression also results in cell non-autonomous stimulation of BP proliferation followed by increased production of upper-layer neurons. Collectively, our findings demonstrate that Sox9 exerts concerted effects on transcription, BP proliferation, neuron production, and neurogenic as well as gliogenic BP cell fate, suggesting that Sox9 acts a master regulator in the subventricular zone to promote neocortical expansion.

developmental biology↗

bioRxiv2017

Evolution and cell-type specificity of human-specific genes preferentially expressed in progenitors of fetal neocortex

To understand the molecular basis underlying the expansion of the neocortex during primate, and notably human, evolution, it is essential to identify the genes that are particularly active in the neural stem and progenitor cells of developing neocortex. Here, we have used existing transcriptome datasets to carry out a comprehensive screen for protein-coding genes preferentially expressed in progenitors of fetal human neocortex. In addition to the previously studied gene ARHGAP11B, we show that ten known and two newly identified human-specific genes exhibit such expression, however with distinct neural progenitor cell-type specificity compared to their ancestral paralogs. Furthermore, we identify 41 additional human genes with progenitor-enriched expression which have orthologs only in primates. Our study not only provides a resource of genes that are candidates to exert specific, and novel, roles in neocortical development, but also reveals that distinct mechanisms gave rise to these genes during primate, and notably human, evolution.

developmental biology↗