Shared behavioural impairments in visual perception and place avoidance across different autism models are driven by periaqueductal grey hypoexcitability in Setd5 haploinsufficient mice.

Despite the diverse genetic origins of autism spectrum disorders (ASDs), affected individuals share strikingly similar and correlated behavioural traits that include perceptual and sensory processing challenges. Notably, the severity of these sensory symptoms is often predictive of the expression of other autistic traits. However, the origin of these perceptual deficits remains largely elusive. Here, we show a recurrent impairment in visual threat perception that is similarly impaired in 3 independent mouse models of ASD with different molecular aetiologies. Interestingly, this deficit is associated with reduced avoidance of threatening environments-a nonperceptual trait. Focusing on a common cause of ASDs, the Setd5 gene mutation, we define the molecular mechanism. We show that the perceptual impairment is caused by a potassium channel (Kv1)-mediated hypoexcitability in a subcortical node essential for the initiation of escape responses, the dorsal periaqueductal grey (dPAG). Targeted pharmacological Kv1 blockade rescued both perceptual and place avoidance deficits, causally linking seemingly unrelated trait deficits to the dPAG. Furthermore, we show that different molecular mechanisms converge on similar behavioural phenotypes by demonstrating that the autism models Cul3 and Ptchd1, despite having similar behavioural phenotypes, differ in their functional and molecular alteration. Our findings reveal a link between rapid perception controlled by subcortical pathways and appropriate learned interactions with the environment and define a nondevelopmental source of such deficits in ASD.

Host-directed therapy with 2-deoxy-D-glucose inhibits human rhinoviruses, endemic coronaviruses, and SARS-CoV-2.

Rhinoviruses (RVs) and coronaviruses (CoVs) upregulate host cell metabolic pathways such as glycolysis to meet their bioenergetic demands for rapid multiplication. Using the glycolysis inhibitor 2-deoxy-d-glucose (2-DG), we assessed the dose-dependent inhibition of viral replication of minor- and major-receptor group RVs in epithelial cells. 2-DG disrupted RV infection cycle by inhibiting template negative-strand as well as genomic positive-strand RNA synthesis, resulting in less progeny virus and RV-mediated cell death. Assessment of 2-DG's intracellular kinetics revealed that after a short-exposure to 2-DG, the active intermediate, 2-DG6P, is stored intracellularly for several hours. Finally, we confirmed the antiviral effect of 2-DG on pandemic SARS-CoV-2 and showed for the first time that it also reduces replication of endemic human coronaviruses. These results provide further evidence that 2-DG could be used as a broad-spectrum antiviral.

HepaCAM controls astrocyte self-organization and coupling.

Astrocytes extensively infiltrate the neuropil to regulate critical aspects of synaptic development and function. This process is regulated by transcellular interactions between astrocytes and neurons via cell adhesion molecules. How astrocytes coordinate developmental processes among one another to parse out the synaptic neuropil and form non-overlapping territories is unknown. Here we identify a molecular mechanism regulating astrocyte-astrocyte interactions during development to coordinate astrocyte morphogenesis and gap junction coupling. We show that hepaCAM, a disease-linked, astrocyte-enriched cell adhesion molecule, regulates astrocyte competition for territory and morphological complexity in the developing mouse cortex. Furthermore, conditional deletion of Hepacam from developing astrocytes significantly impairs gap junction coupling between astrocytes and disrupts the balance between synaptic excitation and inhibition. Mutations in HEPACAM cause megalencephalic leukoencephalopathy with subcortical cysts in humans. Therefore, our findings suggest that disruption of astrocyte self-organization mechanisms could be an underlying cause of neural pathology.

A genome-wide library of MADM mice for single-cell genetic mosaic analysis.

Mosaic analysis with double markers (MADM) offers one approach to visualize and concomitantly manipulate genetically defined cells in mice with single-cell resolution. MADM applications include the analysis of lineage, single-cell morphology and physiology, genomic imprinting phenotypes, and dissection of cell-autonomous gene functions in vivo in health and disease. Yet, MADM can only be applied to <25% of all mouse genes on select chromosomes to date. To overcome this limitation, we generate transgenic mice with knocked-in MADM cassettes near the centromeres of all 19 autosomes and validate their use across organs. With this resource, >96% of the entire mouse genome can now be subjected to single-cell genetic mosaic analysis. Beyond a proof of principle, we apply our MADM library to systematically trace sister chromatid segregation in distinct mitotic cell lineages. We find striking chromosome-specific biases in segregation patterns, reflecting a putative mechanism for the asymmetric segregation of genetic determinants in somatic stem cell division.

Generation of excitatory and inhibitory neurons from common progenitors via Notch signaling in the cerebellum.

Brain neurons arise from relatively few progenitors generating an enormous diversity of neuronal types. Nonetheless, a cardinal feature of mammalian brain neurogenesis is thought to be that excitatory and inhibitory neurons derive from separate, spatially segregated progenitors. Whether bi-potential progenitors with an intrinsic capacity to generate both lineages exist and how such a fate decision may be regulated are unknown. Using cerebellar development as a model, we discover that individual progenitors can give rise to both inhibitory and excitatory lineages. Gradations of Notch activity determine the fates of the progenitors and their daughters. Daughters with the highest levels of Notch activity retain the progenitor fate, while intermediate levels of Notch activity generate inhibitory neurons, and daughters with very low levels of Notch signaling adopt the excitatory fate. Therefore, Notch-mediated binary cell fate choice is a mechanism for regulating the ratio of excitatory to inhibitory neurons from common progenitors.

GluD2- and Cbln1-mediated competitive interactions shape the dendritic arbors of cerebellar Purkinje cells.

The synaptotrophic hypothesis posits that synapse formation stabilizes dendritic branches, but this hypothesis has not been causally tested in vivo in the mammalian brain. The presynaptic ligand cerebellin-1 (Cbln1) and postsynaptic receptor GluD2 mediate synaptogenesis between granule cells and Purkinje cells in the molecular layer of the cerebellar cortex. Here we show that sparse but not global knockout of GluD2 causes under-elaboration of Purkinje cell dendrites in the deep molecular layer and overelaboration in the superficial molecular layer. Developmental, overexpression, structure-function, and genetic epistasis analyses indicate that these dendrite morphogenesis defects result from a deficit in Cbln1/GluD2-dependent competitive interactions. A generative model of dendrite growth based on competitive synaptogenesis largely recapitulates GluD2 sparse and global knockout phenotypes. Our results support the synaptotrophic hypothesis at initial stages of dendrite development, suggest a second mode in which cumulative synapse formation inhibits further dendrite growth, and highlight the importance of competition in dendrite morphogenesis.

Lineage Tracing and Clonal Analysis in Developing Cerebral Cortex Using Mosaic Analysis with Double Markers (MADM).

Beginning from a limited pool of progenitors, the mammalian cerebral cortex forms highly organized functional neural circuits. However, the underlying cellular and molecular mechanisms regulating lineage transitions of neural stem cells (NSCs) and eventual production of neurons and glia in the developing neuroepithelium remains unclear. Methods to trace NSC division patterns and map the lineage of clonally related cells have advanced dramatically. However, many contemporary lineage tracing techniques suffer from the lack of cellular resolution of progeny cell fate, which is essential for deciphering progenitor cell division patterns. Presented is a protocol using mosaic analysis with double markers (MADM) to perform in vivo clonal analysis. MADM concomitantly manipulates individual progenitor cells and visualizes precise division patterns and lineage progression at unprecedented single cell resolution. MADM-based interchromosomal recombination events during the G2-X phase of mitosis, together with temporally inducible CreERT2, provide exact information on the birth dates of clones and their division patterns. Thus, MADM lineage tracing provides unprecedented qualitative and quantitative optical readouts of the proliferation mode of stem cell progenitors at the single cell level. MADM also allows for examination of the mechanisms and functional requirements of candidate genes in NSC lineage progression. This method is unique in that comparative analysis of control and mutant subclones can be performed in the same tissue environment in vivo. Here, the protocol is described in detail, and experimental paradigms to employ MADM for clonal analysis and lineage tracing in the developing cerebral cortex are demonstrated. Importantly, this protocol can be adapted to perform MADM clonal analysis in any murine stem cell niche, as long as the CreERT2 driver is present.

Memo1 Tiles the Radial Glial Cell Grid.

What are the mechanisms regulating the orderly buildup of the laminated cerebral cortex during development? In this issue of Neuron, Nakagawa et al. (2019) discovered that Memo1 plays a crucial role by mediating the tiling of the radial glial cell grid.

Haploinsufficiency of the intellectual disability gene SETD5 disturbs developmental gene expression and cognition.

SETD5 gene mutations have been identified as a frequent cause of idiopathic intellectual disability. Here we show that Setd5-haploinsufficient mice present developmental defects such as abnormal brain-to-body weight ratios and neural crest defect-associated phenotypes. Furthermore, Setd5-mutant mice show impairments in cognitive tasks, enhanced long-term potentiation, delayed ontogenetic profile of ultrasonic vocalization, and behavioral inflexibility. Behavioral issues are accompanied by abnormal expression of postsynaptic density proteins previously associated with cognition. Our data additionally indicate that Setd5 regulates RNA polymerase II dynamics and gene transcription via its interaction with the Hdac3 and Paf1 complexes, findings potentially explaining the gene expression defects observed in Setd5-haploinsufficient mice. Our results emphasize the decisive role of Setd5 in a biological pathway found to be disrupted in humans with intellectual disability and autism spectrum disorder.

Subdiagnóstico de depresión en atención primaria, en pacientes del área sur-oriente de Santiago, 2006 / Depression underdiagnosis in the primary healthcare: a study of patient of south-western area of Santiago, during 2006

La depresión es altamente prevalente en Chile, sin embargo, muchos pacientes no son pesquisados por los médicos de atención primaria (MAP). El objetivo de esta estudio es analizarla concordancia entre el diagnóstico de depresión hecho por MAP, respecto a una entrevista clínica estructurada basada en criterios DSM-IV (Manual Diagnóstico y Estadístico de los Trastornos Mentales) para depresión, realizada en un centro de atención secundaria (CAS). Se estudiaron 174 pacientes (edad 57.6 15.1 años, 131 mujeres), derivados por diversas patologías distintas a la depresión, a un CAS, atendidos durante el último mes por MAP. Todos los pacientes fueron evaluados con la escala de ansiedad y depresión de Goldberg (E.A.D.G) y a los probables casos según el instrumento (puntaje 3, subescala depresión) se les realizó una entrevista clínica estructurada basada en criterios DSM-IV para depresión. Treinta y tres pacientes tenían diagnóstico de depresión hecho por MAP. Sin embargo, 103 pacientes (59.2 por ciento) tuvieron puntajes 3 en la E.A.D.G y 59 (33.9 por ciento) cumplieron criterios DSM-IV para depresión. La concordancia entre el diagnóstico de depresión hecho por MAP, respecto al diagnóstico según criterios DSM-IV, mediante el índice Kappa, fue 0.39 (acuerdo débil), existiendo coincidencia positiva sólo en 25 casos. Se observó baja concordancia entre el diagnóstico de depresión hecho por MAP y el realizado a través de una entrevista clínica estructurada, con importante subdiagnóstico, cercano al 60 por ciento. En forma adicional, la aplicación de un test de tamizaje, fue de utilidad para detectar casos previamente no diagnosticados.