RESUMO
PRDM16 is a dynamic transcriptional regulator of various stem cell niches, including adipocytic, hematopoietic, cardiac progenitors, and neural stem cells. PRDM16 has been suggested to contribute to 1p36 deletion syndrome, one of the most prevalent subtelomeric microdeletion syndromes. We report a patient with a de novo nonsense mutation in the PRDM16 coding sequence, accompanied by lissencephaly and microcephaly features. Human stem cells were genetically modified to mimic this mutation, generating cortical organoids that exhibited altered cell cycle dynamics. RNA sequencing of cortical organoids at day 32 unveiled changes in cell adhesion and WNT-signaling pathways. ChIP-seq of PRDM16 identified binding sites in postmortem human fetal cortex, indicating the conservation of PRDM16 binding to developmental genes in mice and humans, potentially at enhancer sites. A shared motif between PRDM16 and LHX2 was identified and further examined through comparison with LHX2 ChIP-seq data from mice. These results suggested a collaborative partnership between PRDM16 and LHX2 in regulating a common set of genes and pathways in cortical radial glia cells, possibly via their synergistic involvement in cortical development.
RESUMO
VIDEO ABSTRACT: The precise connectivity of inputs and outputs is critical for cerebral cortex function; however, the cellular mechanisms that establish these connections are poorly understood. Here, we show that the secreted molecule Sonic Hedgehog (Shh) is involved in synapse formation of a specific cortical circuit. Shh is expressed in layer V corticofugal projection neurons and the Shh receptor, Brother of CDO (Boc), is expressed in local and callosal projection neurons of layer II/III that synapse onto the subcortical projection neurons. Layer V neurons of mice lacking functional Shh exhibit decreased synapses. Conversely, the loss of functional Boc leads to a reduction in the strength of synaptic connections onto layer Vb, but not layer II/III, pyramidal neurons. These results demonstrate that Shh is expressed in postsynaptic target cells while Boc is expressed in a complementary population of presynaptic input neurons, and they function to guide the formation of cortical microcircuitry.
Assuntos
Córtex Cerebral/citologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Proteínas Hedgehog/metabolismo , Rede Nervosa/metabolismo , Neurônios/metabolismo , Tratos Piramidais/fisiologia , Fatores Etários , Animais , Animais Recém-Nascidos , Córtex Cerebral/crescimento & desenvolvimento , Channelrhodopsins , Corpo Caloso/citologia , Corpo Caloso/crescimento & desenvolvimento , Proteínas de Ligação a DNA/metabolismo , Espinhas Dendríticas/metabolismo , Espinhas Dendríticas/fisiologia , Estimulação Elétrica , Eletroporação/métodos , Fluorbenzenos/metabolismo , Lateralidade Funcional/genética , Furanos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Proteínas Hedgehog/genética , Imunoglobulina G/genética , Imunoglobulina G/metabolismo , Técnicas In Vitro , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Proteínas de Ligação à Região de Interação com a Matriz/metabolismo , Potenciais da Membrana/genética , Camundongos , Camundongos Transgênicos , Mutação/genética , Rede Nervosa/citologia , Neurônios/ultraestrutura , Proteínas Nucleares/metabolismo , Técnicas de Patch-Clamp , Fosfopiruvato Hidratase/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Proteínas Repressoras/metabolismo , Coloração pela Prata/métodos , Estilbamidinas/metabolismo , Sinapses/metabolismo , Sinapses/ultraestrutura , Sinaptofisina/genética , Sinaptofisina/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina-Proteína Ligases , Ácido gama-Aminobutírico/metabolismoRESUMO
Neural stem cells (NSCs) persist in the subventricular zone (SVZ) of the adult brain. Location within this germinal region determines the type of neuronal progeny NSCs generate, but the mechanism of adult NSC positional specification remains unknown. We show that sonic hedgehog (Shh) signaling, resulting in high gli1 levels, occurs in the ventral SVZ and is associated with the genesis of specific neuronal progeny. Shh is selectively produced by a small group of ventral forebrain neurons. Ablation of Shh decreases production of ventrally derived neuron types, while ectopic activation of this pathway in dorsal NSCs respecifies their progeny to deep granule interneurons and calbindin-positive periglomerular cells. These results show that Shh is necessary and sufficient for the specification of adult ventral NSCs.