The nucleus is a highly structured organelle and contains many functional compartments. Although the structural basis for this complex spatial organization of compartments is unknown, a major component of this organization is likely to be the non-chromatin scaffolding called nuclear matrix (NuMat). Experimental evidence over the past decades indicates that most of the nuclear functions are at least transiently associated with the NuMat, although the components of NuMat itself are poorly known. Here, we report NuMat proteome analysis from Drosophila melanogaster embryos and discuss its links with nuclear architecture and functions. In the NuMat proteome, we found structural proteins, chaperones, DNA/RNAbinding proteins, chromatin remodeling and transcription factors. This complexity of NuMat proteome is an indicator of its structural and functional significance. The eukaryotic cell nucleus contains a number of structural features like heterochromatin, nucleolus, nuclear lamina, and nuclear territories and functional features like transcription foci, replication foci, Cajal bodies, stress-induced foci, etc.(1-7). Packaging of the genome on the other hand also results in non-random distribution of a variety of structural features like chromatin domains that help to regulate expression of genes (8). How these complex structural and functional domains are established and maintained is not known. It is likely that the non-chromatin scaffolding called nuclear matrix (9) plays an important role in this process. Nuclear matrix (NuMat) 1 mainly consists of the nuclear lamina, the nucleolar remnants, and an internal nuclear meshwork of fibers of unknown constitution that can be seen by electron microscopy (10). These fibers have ultrastructural features reminiscent of intermediate filaments of the cytosol (11). The protein component of nucleoplasmic filaments, however, is largely unknown. Earlier studies on a few proteins isolated from nuclear matrix from different organisms have shown them to be DNA-and RNA-binding and structural components of the nuclear pore complex (12), enzymes (13), and nuclear membrane proteins (14). This diversity among the small number of identified NuMat constituents reflects the link of nuclear architecture with the variety of nuclear functions. The importance of NuMat constituents in nuclear processes has been apparent for a long time, and several studies have been carried out to identify the proteins of this complex structure in different organisms (15-18). Major advancements in the field of proteomics now provide further scope for extensive analysis of NuMat in this context.Here, we present a comprehensive analysis of the NuMat proteome of Drosophila melanogaster. NuMat preparations from D. melanogaster embryos were separated by one-dimensional gel electrophoresis, and the proteins were identified by LC-MS/MS. We also report a remarkable variation in the NuMat proteome depending on developmental stages, indicating a link between embryonic development and nuclear architecture. Finally, immunos...

Embryonic development is a complex and dynamic process that involves spatiotemporal expression of genes in a highly coordinated manner. Multiple levels of nuclear architecture maintain the fidelity of gene expression programme. One of the components of nuclear architecture, which is believed to play an important role in regulation of gene expression, is the nuclear matrix (NuMat). Many studies over the past few years have tried to analyse the components of this non-chromatin scaffolding of the nucleus and have provided evidences of its structural and functional complexity. However, the relationship of NuMat with the process of embryonic development still remains poorly understood. Here, we report a comparative analysis of the NuMat proteomes of early and late stage Drosophila melanogaster embryos and show that 65% of the NuMat proteome is dynamic during development. Our study establishes links between the dynamics of nuclear architecture and embryonic development and provides tools to further understand the process such as cellular differentiation in the context of higher-order nuclear organization.

In the mammalian hippocampus, adult-born granule cells (abGCs) contribute to the function of the dentate gyrus (DG). Disruption of the DG circuitry causes spontaneous recurrent seizures (SRS), which can lead to epilepsy. Although abGCs contribute to local inhibitory feedback circuitry, whether they are involved in epileptogenesis remains elusive. Here, we identify a critical window of activity associated with the aberrant maturation of abGCs characterized by abnormal dendrite morphology, ectopic migration, and SRS. Importantly, in a mouse model of temporal lobe epilepsy, silencing aberrant abGCs during this critical period reduces abnormal dendrite morphology, cell migration, and SRS. Using mono-synaptic tracers, we show silencing aberrant abGCs decreases recurrent CA3 back-projections and restores proper cortical connections to the hippocampus. Furthermore, we show that GABA-mediated amplification of intracellular calcium regulates the early critical period of activity. Our results demonstrate that aberrant neurogenesis rewires hippocampal circuitry aggravating epilepsy in mice.

Mesial temporal lobe epilepsy (mTLE), the most common form of medically refractory epilepsy in adults, is usually associated with hippocampal pathophysiology. Using rodent models of mTLE, many studies including work from our laboratory have shown that new neurons born around the onset of severe acute seizures known as status epilepticus (SE) are crucial for the process of epileptogenesis and targeting seizure-induced neurogenesis either genetically or pharmacologically can impact the frequency of chronic seizures. However, these studies are limited in their clinical relevance as none of them determines the potential of blocking new neurons generated after the epileptogenic insult to alleviate the development of chronic seizures. Therefore, using a pilocarpine-induced SE model of mTLE in mice of either sex, we show that Ͼ4 weeks of continuous and concurrent ablation of seizure-induced neurogenesis after SE can reduce the formation of spontaneous recurrent seizures by 65%. We also found that blocking post-SE neurogenesis does not lead to long-term seizure reduction as the effect was observed only transiently for 10 d with Ͼ4 weeks of continuous and concurrent ablation of seizureinduced neurogenesis. Thus, these findings provide evidence that seizure-induced neurogenesis when adequately reduced in a clinically relevant time period has the potential to transiently suppress recurrent seizures, but additional mechanisms need to be targeted to permanently prevent epilepsy development.

Pregnant women are at greater risk of infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), because of their altered immunity and strained cardiovascular system. Emerging studies of placenta, embryos, and cerebral organoids suggest that fetal organs including brain could also be vulnerable to coronavirus disease 2019 (COVID-19). Additionally, a case study from Paris has reported transient neurological complications in neonates born to pregnant mothers. However, it remains poorly understood whether the fetal brain expresses cellular components that interact with Spike protein (S) of coronaviruses, which facilitates fusion of virus and host cell membrane and is the primary protein in viral entry. To address this question, we analyzed the expression of known (ACE2, TMPRSS2, and FURIN) and novel (ZDHHC5, GOLGA7, and ATP1A1) S protein interactors in publicly available fetal brain bulk and single cell RNA sequencing datasets. Bulk RNA sequencing analysis across multiple regions of fetal brain spanning 8 weeks post conception (wpc)−37wpc indicates that two of the known S protein interactors are expressed at low levels with median normalized gene expression values ranging from 0.08 to 0.06 (ACE2) and 0.01–0.02 (TMPRSS2). However, the third known S protein interactor FURIN is highly expressed (11.1–44.09) in fetal brain. Interestingly, all three novel S protein interactors are abundantly expressed throughout fetal brain development with median normalized gene expression values ranging from 20.38–21.60 (ZDHHC5), 92.47–68.35 (GOLGA7), and 65.45–194.5 (ATP1A1). Moreover, the peaks of expression of novel interactors is around 12–26wpc. Using publicly available single cell RNA sequencing datasets, we further show that novel S protein interactors show higher co-expression with neurons than with neural progenitors and astrocytes. These results suggest that even though two of the known S protein interactors are present at low levels in fetal brain, novel S protein interactors are abundantly present and could play a direct or indirect role in SARS-CoV-2 fetal brain pathogenesis, especially during the 2nd and 3rd trimesters of pregnancy.

The misuse of opioids has reached epidemic proportions over the last decade, with over 2.1 million people in the United States suffering from substance use disorders related to prescription opioid pain relievers. This increase in opioid misuse affects all demographics of society, including women of child-bearing age, which has led to a rise in opioid use during pregnancy. Opioid use during pregnancy has been associated with increased risk of obstetric complications and adverse neonatal outcomes, including neonatal abstinence syndrome. Currently, opioid use disorder in pregnant women is treated with long-acting opioid agonists, including buprenorphine. Although buprenorphine reduces illicit opioid use during pregnancy and improves infant outcomes at birth, few long-term studies of the neurodevelopmental consequences have been conducted. The goal of the current experiments was to examine the effects of buprenorphine on the development of the cortex using fetal brain tissue, 3D brain cultures, and rodent models. First, we demonstrated that we can grow cortical and subpallial spheroids, which model the cellular diversity, connectivity, and activity of the developing human brain. Next, we show that cells in the developing human cortex express the nociceptin opioid (NOP) receptor and that buprenorphine can signal through this receptor in cortical spheroids. Using subpallial spheroids to grow inhibitory interneurons, we show that buprenorphine can alter interneuron development and migration into the cortex. Finally, using a rodent model of prenatal buprenorphine exposure, we demonstrate that alterations in interneuron distribution can persist into adulthood. Together, these results suggest that more research is needed into the long-lasting consequences of buprenorphine exposure on the developing human brain.

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Highlights d Dentate granule cells undergo repositioning before circuit integration d Sphingolipid signaling is promptly activated and regulates repositioning d S1PR1 is activated by hippocampus-engaged behavior and regulates the repositioning