Implications of mRNA translation dysregulation for neurological disorders

Exploiting the SunTag system to study the developmental regulation of mRNA translation

The ability to quantitatively study mRNA translation using SunTag imaging is transforming our understanding of the translation process. Here, we expand the SunTag method to study new aspects of translation regulation in Drosophila. Repression of the maternal hunchback (hb) mRNA in the posterior of the Drosophila embryo is a textbook example of translational control. Using SunTag imaging to quantify translation of maternal SunTag-hb mRNAs, we show that repression in the posterior is leaky, as ∼5% of SunTag-hb mRNAs are translated. In the anterior of the embryo, the maternal and zygotic SunTag-hb mRNAs show similar translation efficiency despite having different untranslated regions (UTRs). We demonstrate that the SunTag-hb mRNA can be used as a reporter to study ribosome pausing at single-mRNA resolution, by exploiting the conserved xbp1 mRNA and A60 pausing sequences. Finally, we adapt the detector component of the SunTag system to visualise and quantify translation of the short gastrulation (sog) mRNA, encoding an essential secreted extracellular BMP regulator, at the endoplasmic reticulum in fixed and live embryos. Together, these tools will facilitate the future dissection of translation regulatory mechanisms during development.

Small for gestational age children at risk: Identifying placenta-brain axis genes as biomarkers for early prediction of neurodevelopmental delay

AIMS

Small for gestational age (SGA) is a prevalent issue in global public health. The relationship between SGA and neurodevelopmental delay remains a topic of debate and the exploration of potential biomarkers is crucial. The identification of placental-brain axis genes offers novel perspectives for anticipating neurodevelopmental delay.

MAIN METHODS

First, we utilized multiple logistic regression to assess Ages and Stages Questionnaire of China (ASQ-C) scores in children at 6 months, 18 months, and 48 months of age. Next, we analyzed the placental transcriptome data from SGA and appropriate for gestational age (AGA) children in the Ma'anshan Birth Cohort (MABC) and validated it through Real-time quantitative PCR (RT-qPCR). Finally, we combined the experimental data with clinical data to establish a predictive model.

KEY FINDINGS

SGA children were found to have a higher risk of neurodevelopmental delay at 6 months and 18 months of age. Further experimental validation found that decreased RPS27A gene expression was associated with developmental delay in solving-problem and personal-social domain at 6 months of age in SGA children.

SIGNIFICANCE

Our study focused on the neurodevelopmental results of children from three time points, analyzed the mechanism of neurodevelopmental delay in SGA from the perspective of placenta-brain axis, and conducted experimental verification of the selected biomarkers. Therefore, our study has certain novelty and persuasive, providing new insights for early detection of neurodevelopmental delay in children with SGA.

Dysregulated ribosome quality control in human diseases

Precise regulation of mRNA translation is of fundamental importance for maintaining homeostasis. Conversely, dysregulated general or transcript-specific translation, as well as abnormal translation events, have been linked to a multitude of diseases. However, driven by the misconception that the transient nature of mRNAs renders their abnormalities inconsequential, the importance of mechanisms that monitor the quality and fidelity of the translation process has been largely overlooked. In recent years, there has been a dramatic shift in this paradigm, evidenced by several seminal discoveries on the role of a key mechanism in monitoring the quality of mRNA translation - namely, Ribosome Quality Control (RQC) - in the maintenance of homeostasis and the prevention of diseases. Here, we will review recent advances in the field and emphasize the biological significance of the RQC mechanism, particularly its implications in human diseases.

Investigation of the mesencephalic astrocyte-derived neurotrophic factor-endoplasmic reticulum stress pathway in mood disorders

BACKGROUND

Bipolar disorder (BD) has been associated with impaired cellular resilience. Recent studies have shown abnormalities in the unfolded protein response (UPR) in BD. The UPR is the cellular response to endoplasmic reticulum (ER) stress. Mesencephalic astrocyte-derived neurotrophic factor (MANF), a trophic factor, decreases ER stress by modulating the UPR. The objective of this study is to investigate the MANF-ER stress pathway in BD and major depressive disorder (MDD) compared to healthy controls (HC).

METHODS

MANF protein concentration and MANF and GRP78 gene expression were assessed in peripheral blood from individuals with BD, MDD, and HC (protein: 40 BD, 55 MDD, 55 HC; gene expression: 52 BD, 61 MDD, 69 HC). MANF protein and gene expression along with GRP78 gene expression were also analyzed in postmortem brain tissue (20 BD, 20 MDD, 19 HC). MANF protein was quantified using an ELISA assay while quantitative polymerase chain reaction was used for MANF and GRP78 gene expression.

RESULTS

Peripheral MANF protein levels were reduced in individuals with BD in a depressive state compared to controls (P = .031) and euthymic BD participants (P = .013). No significant differences in MANF or GRP78 gene expression were observed in BD irrespective of mood state, or MDD compared to HC (all P > .05). No differences were observed regarding MANF/GRP78 protein or gene expression levels in postmortem tissue (P > .05).

CONCLUSIONS

Individuals with BD who were in an acute depressive phase were found to have reduced peripheral MANF levels potentially signifying abnormal UPR and supporting the notion that BD is associated with increased ER stress.

Maternal immune activation imprints translational dysregulation and differential MAP2 phosphorylation in descendant neural stem cells

Alterations induced by maternal immune activation (MIA) during gestation impact the subsequent neurodevelopment of progeny, a process that in humans, has been linked to the development of several neuropsychiatric conditions. To undertake a comprehensive examination of the molecular mechanisms governing MIA, we have devised an in vitro model based on neural stem cells (NSCs) sourced from fetuses carried by animals subjected to Poly I:C treatment. These neural progenitors demonstrate proliferative capacity and can be effectively differentiated into both neurons and glial cells. Transcriptomic, proteomic, and phosphoproteomic analyses conducted on these cellular models, in conjunction with counterparts from control treatments, revealed discernible shifts in the expression levels of a specific subset of proteins implicated in neuronal function. Furthermore, the phosphoproteomic data highlighted a discernible discrepancy in the basal phosphorylation of proteins between differentiated cells from both experimental groups, particularly within proteins associated with cytoskeletal architecture and synaptic functionality, notably those belonging to the MAP family. Observed alterations in MAP phosphorylation were found to potentially have functional consequences as they correlate with changes in neuronal plasticity and the establishment of neuronal synapses. Our data agrees with previous published observations and further underscore the importance of MAP2 phosphorylation state on its function and the impact that this protein has in neuronal structure and function.

Epigenetic Mechanisms in Aging: Extrinsic Factors and Gut Microbiome

BACKGROUND/OBJECTIVES

Aging is a natural physiological process involving biological and genetic pathways. Growing evidence suggests that alterations in the epigenome during aging result in transcriptional changes, which play a significant role in the onset of age-related diseases, including cancer, cardiovascular disease, diabetes, and neurodegenerative disorders. For this reason, the epigenetic alterations in aging and age-related diseases have been reviewed, and the major extrinsic factors influencing these epigenetic alterations have been identified. In addition, the role of the gut microbiome and its metabolites as epigenetic modifiers has been addressed.

RESULTS

Long-term exposure to extrinsic factors such as air pollution, diet, drug use, environmental chemicals, microbial infections, physical activity, radiation, and stress provoke epigenetic changes in the host through several endocrine and immune pathways, potentially accelerating the aging process. Diverse studies have reported that the gut microbiome plays a critical role in regulating brain cell functions through DNA methylation and histone modifications. The interaction between genes and the gut microbiome serves as a source of adaptive variation, contributing to phenotypic plasticity. However, the molecular mechanisms and signaling pathways driving this process are still not fully understood.

CONCLUSIONS

Extrinsic factors are potential inducers of epigenetic alterations, which may have important implications for longevity. The gut microbiome serves as an epigenetic effector influencing host gene expression through histone and DNA modifications, while bidirectional interactions with the host and the underexplored roles of microbial metabolites and non-bacterial microorganisms such as fungi and viruses highlight the need for further research.

Decoding the molecular script of 2'-O-ribomethylation: Implications across CNS disorders

Emerging evidence underscores the critical role of impaired mRNA translation in various neurobiological conditions. Ribosomal RNA (rRNA), essential for protein synthesis, undergoes crucial post-transcriptional modifications such as 2'-O-ribose methylation, pseudouridylation, and base modifications. These modifications, particularly 2'-O-ribose methylation is vital for stabilizing rRNA structures and optimizing translation efficiency by regulating RNA integrity and its interactions with proteins. Concentrated in key regions like decoding sites and the peptidyl transferase center, dysregulation of these modifications can disrupt ribosomal function, contributing to the pathogenesis of diverse neurological conditions, including mental health disorders, developmental abnormalities, and neurodegenerative diseases. Mechanistically, 2'-O-ribose methylation involves interactions between small nucleolar RNAs (snoRNAs), snoRNPs, and fibrillarin, forming a complex regulatory network crucial for maintaining ribosomal integrity and function. Recent research highlights the association of defective ribosome biogenesis with a spectrum of CNS disorders, emphasizing the importance of understanding rRNA mechanisms in disease pathology. This review focuses on the pivotal role of 2'-O-ribose methylation in shaping ribosomal function and its potential implications for unraveling the pathophysiology of CNS disorders. Insights gained from studying these RNA modifications could pave the way for new therapeutic strategies targeting ribosomal dysfunction and associated neuropathological conditions, advancing precision medicine and therapeutic interventions.

RTP801 interacts with the tRNA ligase complex and dysregulates its RNA ligase activity in Alzheimer's disease

RTP801/REDD1 is a stress-responsive protein overexpressed in neurodegenerative diseases such as Alzheimer's disease (AD) that contributes to cognitive deficits and neuroinflammation. Here, we found that RTP801 interacts with HSPC117, DDX1 and CGI-99, three members of the tRNA ligase complex (tRNA-LC), which ligates the excised exons of intron-containing tRNAs and the mRNA exons of the transcription factor XBP1 during the unfolded protein response (UPR). We also found that RTP801 modulates the mRNA ligase activity of the complex in vitro since RTP801 knockdown promoted XBP1 splicing and the expression of its transcriptional target, SEC24D. Conversely, RTP801 overexpression inhibited the splicing of XBP1. Similarly, in human AD postmortem hippocampal samples, where RTP801 is upregulated, we found that XBP1 splicing was dramatically decreased. In the 5xFAD mouse model of AD, silencing RTP801 expression in hippocampal neurons promoted Xbp1 splicing and prevented the accumulation of intron-containing pre-tRNAs. Finally, the tRNA-enriched fraction obtained from 5xFAD mice promoted abnormal dendritic arborization in cultured hippocampal neurons, and RTP801 silencing in the source neurons prevented this phenotype. Altogether, these results show that elevated RTP801 impairs RNA processing in vitro and in vivo in the context of AD and suggest that RTP801 inhibition could be a promising therapeutic approach.

Neurodevelopmental disorder-associated CYFIP2 regulates membraneless organelles and eIF2α phosphorylation via protein interactors and actin cytoskeleton

De novo variants in the Cytoplasmic FMR1-interacting protein 2 (CYFIP2) have been repeatedly associated with neurodevelopmental disorders and epilepsy, underscoring its critical role in brain development and function. While CYFIP2's role in regulating actin polymerization as part of the WAVE regulatory complex (WRC) is well-established, its additional molecular functions remain relatively unexplored. In this study, we performed unbiased quantitative proteomic analysis, revealing 278 differentially expressed proteins (DEPs) in the forebrain of Cyfip2 knock-out embryonic mice compared to wild-type mice. Unexpectedly, these DEPs, in conjunction with previously identified CYFIP2 brain interactors, included not only other WRC components but also numerous proteins associated with membraneless organelles (MLOs) involved in mRNA processing and translation within cells, including the nucleolus, stress granules, and processing bodies. Additionally, single-cell transcriptomic analysis of the Cyfip2 knock-out forebrain revealed gene expression changes linked to cellular stress responses and MLOs. We also observed morphological changes in MLOs in Cyfip2 knock-out brains and CYFIP2 knock-down cells under basal and stress conditions. Lastly, we demonstrated that CYFIP2 knock-down in cells, potentially through WRC-dependent actin regulation, suppressed the phosphorylation levels of the alpha subunit of eukaryotic translation initiation factor 2 (eIF2α), thereby enhancing protein synthesis. These results suggest a physical and functional connection between CYFIP2 and various MLO proteins and also extend CYFIP2's role within the WRC from actin regulation to influencing eIF2α phosphorylation and protein synthesis. With these dual functions, CYFIP2 may fine-tune the balance between MLO formation/dynamics and protein synthesis, a crucial aspect of proper mRNA processing and translation.

Implications of altered pyramidal cell morphology on clinical symptoms of neurodevelopmental disorders

The prevalence of pyramidal cells (PCs) in the mammalian cerebral cortex underscore their value as they play a crucial role in various brain functions, ranging from cognition, sensory processing, to motor output. PC morphology significantly influences brain connectivity and plays a critical role in maintaining normal brain function. Pathological alterations to PC morphology are thought to contribute to the aetiology of neurodevelopmental disorders such as autism spectrum disorder (ASD) and schizophrenia. This review explores the relationship between abnormalities in PC morphology in key cortical areas and the clinical manifestations in schizophrenia and ASD. We focus largely on human postmortem studies and provide evidence that dendritic segment length, complexity and spine density are differentially affected in these disorders. These morphological alterations can lead to disruptions in cortical connectivity, potentially contributing to the cognitive and behavioural deficits observed in these disorders. Furthermore, we highlight the importance of investigating the functional and structural characteristics of PCs in these disorders to illuminate the underlying pathogenesis and stimulate further research in this area.

Novel Insights into Changes in Gene Expression within the Hypothalamus in Two Asthma Mouse Models: A Transcriptomic Lung-Brain Axis Study

Patients with asthma experience elevated rates of mental illness. However, the molecular links underlying such lung-brain crosstalk remain ambiguous. Hypothalamic dysfunction is observed in many psychiatric disorders, particularly those with an inflammatory component due to many hypothalamic regions being unprotected by the blood-brain barrier. To gain a better insight into such neuropsychiatric sequelae, this study investigated gene expression differences in the hypothalamus following lung inflammation (asthma) induction in mice, using RNA transcriptome profiling. BALB/c mice were challenged with either bacterial lipopolysaccharide (LPS, E. coli) or ovalbumin (OVA) allergens or saline control (n = 7 per group), and lung inflammation was confirmed via histological examination of postmortem lung tissue. The majority of the hypothalamus was micro-dissected, and total RNA was extracted for sequencing. Differential expression analysis identified 31 statistically significant single genes (false discovery rate FDR5%) altered in expression following LPS exposure compared to controls; however, none were significantly changed following OVA treatment, suggesting a milder hypothalamic response. When gene sets were examined, 48 were upregulated and 8 were downregulated in both asthma groups relative to controls. REACTOME enrichment analysis suggests these gene sets are involved in signal transduction metabolism, immune response and neuroplasticity. Interestingly, we identified five altered gene sets directly associated with neurotransmitter signaling. Intriguingly, many of these altered gene sets can influence mental health and or/neuroinflammation in humans. These findings help characterize the links between asthma-induced lung inflammation and the brain and may assist in identifying relevant pathways and therapeutic targets for future intervention.

Maternal Immune Activation imprints translational dysregulation and differential MAP2 phosphorylation in descendant neural stem cells

Alterations induced by maternal immune activation (MIA) during gestation impact the subsequent neurodevelopment of progeny, a process that in humans, has been linked to the development of several neuropsychiatric conditions. To undertake a comprehensive examination of the molecular mechanisms governing MIA, we have devised an in vitro model based on neural stem cells (NSCs) sourced from fetuses carried by animals subjected to Poly I:C treatment. These neural progenitors demonstrate proliferative capacity and can be effectively differentiated into both neurons and glial cells. Transcriptomic, proteomic, and phosphoproteomic analyses conducted on these cellular models, in conjunction with counterparts from control treatments, revealed discernible shifts in the expression levels of a specific subset of proteins implicated in neuronal function. Noteworthy, we found an absence of congruence between these alterations at the transcriptomic level, suggesting that differences in protein translation contribute to the observed dysregulation. Furthermore, the phosphoproteomic data highlighted a discernible discrepancy in the basal phosphorylation of proteins between differentiated cells from both experimental groups, particularly within proteins associated with cytoskeletal architecture and synaptic functionality, notably those belonging to the MAP family. Observed alterations in MAP phosphorylation were found to potentially have functional consequences as they correlate with changes in neuronal plasticity and the establishment of neuronal synapses. Our data agrees with previous published observations and further underscore the importance of MAP2 phosphorylation state on its function and the impact that this protein has in neuronal structure and function.

eIF4F complex dynamics are important for the activation of the integrated stress response

In response to stress, eukaryotes activate the integrated stress response (ISR) via phosphorylation of eIF2α to promote the translation of pro-survival effector genes, such as GCN4 in yeast. Complementing the ISR is the target of rapamycin (TOR) pathway, which regulates eIF4E function. Here, we probe translational control in the absence of eIF4E in Saccharomyces cerevisiae. Intriguingly, we find that loss of eIF4E leads to de-repression of GCN4 translation. In addition, we find that de-repression of GCN4 translation is accompanied by neither eIF2α phosphorylation nor reduction in initiator ternary complex (TC). Our data suggest that when eIF4E levels are depleted, GCN4 translation is de-repressed via a unique mechanism that may involve faster scanning by the small ribosome subunit due to increased local concentration of eIF4A. Overall, our findings suggest that relative levels of eIF4F components are key to ribosome dynamics and may play important roles in translational control of gene expression.

Role of epigenetics and alterations in RNA metabolism in leukodystrophies

Leukodystrophies are a class of rare heterogeneous disorders which affect the white matter of the brain, ultimately leading to a disruption in brain development and a damaging effect on cognitive, motor and social-communicative development. These disorders present a great clinical heterogeneity, along with a phenotypic overlap and this could be partially due to contributions from environmental stimuli. It is in this context that there is a great need to investigate what other factors may contribute to both disease insurgence and phenotypical heterogeneity, and novel evidence are raising the attention toward the study of epigenetics and transcription mechanisms that can influence the disease phenotype beyond genetics. Modulation in the epigenetics machinery including histone modifications, DNA methylation and non-coding RNAs dysregulation, could be crucial players in the development of these disorders, and moreover an aberrant RNA maturation process has been linked to leukodystrophies. Here, we provide an overview of these mechanisms hoping to supply a closer step toward the analysis of leukodystrophies not only as genetically determined but also with an added level of complexity where epigenetic dysregulation is of key relevance. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNA RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.

Dissecting 16p11.2 hemi-deletion to study sex-specific striatal phenotypes of neurodevelopmental disorders

Neurodevelopmental disorders (NDDs) are polygenic in nature and copy number variants (CNVs) are ideal candidates to study the nature of this polygenic risk. The disruption of striatal circuits is considered a central mechanism in NDDs. The 16p11.2 hemi-deletion (16p11.2 del/+) is one of the most common CNVs associated with NDD, and 16p11.2 del/+ mice show sex-specific striatum-related behavioral phenotypes. However, the critical genes among the 27 genes in the 16p11.2 region that underlie these phenotypes remain unknown. Previously, we applied a novel strategy to identify candidate genes associated with the sex-specific phenotypes of 16p11.2 del/+ mice and highlighted three genes within the deleted region: thousand and one amino acid protein kinase 2 (Taok2), seizure-related 6 homolog-like 2 (Sez6l2), and major vault protein (Mvp). Using CRISPR/Cas9, we generated mice carrying null mutations in Taok2, Sez6l2, and Mvp (3 gene hemi-deletion (3g del/+)). Hemi-deletion of these 3 genes recapitulates sex-specific behavioral alterations in striatum-dependent behavioral tasks observed in 16p11.2 del/+ mice, specifically male-specific hyperactivity and impaired motivation for reward seeking. Moreover, RNAseq analysis revealed that 3g del/+ mice exhibit gene expression changes in the striatum similar to 16p11.2 del/+ mice exclusively in males. Subsequent analysis identified translation dysregulation and/or extracellular signal-regulated kinase signaling as plausible molecular mechanisms underlying male-specific, striatum-dependent behavioral alterations. Interestingly, ribosomal profiling supported the notion of translation dysregulation in both 3g del/+ and 16p11.2 del/+ male mice. However, mice carrying a 4-gene deletion (with an additional deletion of Mapk3) exhibited fewer phenotypic similarities with 16p11.2 del/+ mice. Together, the mutation of 3 genes within the 16p11.2 region phenocopies striatal sex-specific phenotypes of 16p11.2 del/+ mice. These results support the importance of a polygenic approach to study NDDs and underscore that the effects of the large genetic deletions result from complex interactions between multiple candidate genes.

FMRP Long-Range Transport and Degradation Are Mediated by Dynlrb1 in Sensory Neurons

The fragile X messenger ribonucleoprotein 1 (FMRP) is a multifunctional RNA-binding protein implicated in human neurodevelopmental and neurodegenerative disorders. FMRP mediates the localization and activity-dependent translation of its associated mRNAs through the formation of phase-separated condensates that are trafficked by microtubule-based motors in axons. Axonal transport and localized mRNA translation are critical processes for long-term neuronal survival and are closely linked to the pathogenesis of neurological diseases. FMRP dynein-mediated axonal trafficking is still largely unexplored but likely to constitute a key process underlying FMRP spatiotemporal translational regulation. Here, we show that dynein light chain roadblock 1 (Dynlrb1), a subunit of the dynein complex, is a critical regulator of FMRP function. In sensory axons, FMRP associates with endolysosomal organelles, likely through annexin A11, and is retrogradely trafficked by the dynein complex in a Dynlrb1-dependent manner. Moreover, Dynlrb1 silencing induced FMRP granule accumulation and repressed the translation of microtubule-associated protein 1b, one of its primary mRNA targets. Our findings suggest that Dynlrb1 regulates FMRP function through the control of its transport and targeted degradation.

Complex CDKL5 translational regulation and its potential role in CDKL5 deficiency disorder

CDKL5 is a kinase with relevant functions in correct neuronal development and in the shaping of synapses. A decrease in its expression or activity leads to a severe neurodevelopmental condition known as CDKL5 deficiency disorder (CDD). CDD arises from CDKL5 mutations that lie in the coding region of the gene. However, the identification of a SNP in the CDKL5 5'UTR in a patient with symptoms consistent with CDD, together with the complexity of the CDKL5 transcript leader, points toward a relevant translational regulation of CDKL5 expression with important consequences in physiological processes as well as in the pathogenesis of CDD. We performed a bioinformatics and molecular analysis of the 5'UTR of CDKL5 to identify translational regulatory features. We propose an important role for structural cis-acting elements, with the involvement of the eukaryotic translational initiation factor eIF4B. By evaluating both cap-dependent and cap-independent translation initiation, we suggest the presence of an IRES supporting the translation of CDKL5 mRNA and propose a pathogenic effect of the C>T -189 SNP in decreasing the translation of the downstream protein.

Loss of Paip1 causes translation reduction and induces apoptotic cell death through ISR activation and Xrp1

Regulation of protein translation initiation is tightly associated with cell growth and survival. Here, we identify Paip1, the Drosophila homolog of the translation initiation factor PAIP1, and analyze its role during development. Through genetic analysis, we find that loss of Paip1 causes reduced protein translation and pupal lethality. Furthermore, tissue specific knockdown of Paip1 results in apoptotic cell death in the wing imaginal disc. Paip1 depletion leads to increased proteotoxic stress and activation of the integrated stress response (ISR) pathway. Mechanistically, we show that loss of Paip1 promotes phosphorylation of eIF2α via the kinase PERK, leading to apoptotic cell death. Moreover, Paip1 depletion upregulates the transcription factor gene Xrp1, which contributes to apoptotic cell death and eIF2α phosphorylation. We further show that loss of Paip1 leads to an increase in Xrp1 translation mediated by its 5'UTR. These findings uncover a novel mechanism that links translation impairment to tissue homeostasis and establish a role of ISR activation and Xrp1 in promoting cell death.

Dissecting 16p11.2 hemi-deletion to study sex-specific striatal phenotypes of neurodevelopmental disorders

Neurodevelopmental disorders (NDDs) are polygenic in nature and copy number variants (CNVs) are ideal candidates to study the nature of this polygenic risk. The disruption of striatal circuits is considered a central mechanism in NDDs. The 16p11.2 hemi-deletion (16p11.2 del) is one of the most common CNVs associated with NDD, and 16p11.2 del/+ mice show sex-specific striatum-related behavioral phenotypes. However, the critical genes among the 27 genes in the 16p11.2 region that underlie these phenotypes remain unknown. Previously, we applied a novel strategy to identify candidate genes associated with the sex-specific phenotypes of 16p11.2 del/+ mice and identified 3 genes of particular importance within the deleted region: thousand and one amino acid protein kinase 2 (Taok2), seizure-related 6 homolog-like 2 (Sez6l2), and major vault protein (Mvp). Using the CRISPR/Cas9 technique, we generated 3 gene hemi-deletion (3g del/+) mice carrying null mutations in Taok2, Sez6l2, and Mvp. We assessed striatum-dependent phenotypes of these 3g del/+ mice in behavioral, molecular, and imaging studies. Hemi-deletion of Taok2, Sez6l2, and Mvp induces sex-specific behavioral alterations in striatum-dependent behavioral tasks, specifically male-specific hyperactivity and impaired motivation for reward seeking, resembling behavioral phenotypes of 16p11.2 del/+ mice. Moreover, RNAseq analysis revealed that 3g del/+ mice exhibit gene expression changes in the striatum similar to 16p11.2 del/+ mice, but only in males. Pathway analysis identified ribosomal dysfunction and translation dysregulation as molecular mechanisms underlying male-specific, striatum-dependent behavioral alterations. Together, the mutation of 3 genes within the 16p11.2 region phenocopies striatal sex-specific phenotypes of 16p11.2 del/+ mice, unlike single gene mutation studies. These results support the importance of a polygenic approach to study NDDs and our novel strategy to identify genes of interest using gene expression patterns in brain regions, such as the striatum, which are impacted in these disorders.

Dissecting 16p11.2 hemi-deletion to study sex-specific striatal phenotypes of neurodevelopmental disorders

Neurodevelopmental disorders (NDDs) are polygenic in nature and copy number variants (CNVs) are ideal candidates to study the nature of this polygenic risk. The disruption of striatal circuits is considered a central mechanism in NDDs. The 16p11.2 hemi-deletion (16p11.2 del) is one of the most common CNVs associated with NDD, and 16p11.2 del/+ mice show sex-specific striatum-related behavioral phenotypes. However, the critical genes among the 27 genes in the 16p11.2 region that underlie these phenotypes remain unknown. Previously, we applied a novel strategy to identify candidate genes associated with the sex-specific phenotypes of 16p11.2 del/+ mice and identified 3 genes of particular importance within the deleted region: thousand and one amino acid protein kinase 2 ( Taok2 ), seizure-related 6 homolog-like 2 ( Sez6l2 ), and major vault protein ( Mvp ). Using the CRISPR/Cas9 technique, we generated 3 gene hemi-deletion (3g del/+) mice carrying null mutations in Taok2, Sez6l2 , and Mvp . We assessed striatum-dependent phenotypes of these 3g del/+ mice in behavioral, molecular, and imaging studies. Hemi-deletion of Taok2, Sez6l2 , and Mvp induces sex-specific behavioral alterations in striatum-dependent behavioral tasks, specifically male-specific hyperactivity and impaired motivation for reward seeking, resembling behavioral phenotypes of 16p11.2 del/+ mice. Moreover, RNAseq analysis revealed that 3g del/+ mice exhibit gene expression changes in the striatum similar to 16p11.2 del/+ mice, but only in males. Pathway analysis identified ribosomal dysfunction and translation dysregulation as molecular mechanisms underlying male-specific, striatum-dependent behavioral alterations. Together, the mutation of 3 genes within the 16p11.2 region phenocopies striatal sex-specific phenotypes of 16p11.2 del/+ mice, unlike single gene mutation studies. These results support the importance of a polygenic approach to study NDDs and our novel strategy to identify genes of interest using gene expression patterns in brain regions, such as the striatum, which are impacted in these disorders.

Developmental dynamics of RNA translation in the human brain

The precise regulation of gene expression is fundamental to neurodevelopment, plasticity and cognitive function. Although several studies have profiled transcription in the developing human brain, there is a gap in understanding of accompanying translational regulation. In this study, we performed ribosome profiling on 73 human prenatal and adult cortex samples. We characterized the translational regulation of annotated open reading frames (ORFs) and identified thousands of previously unknown translation events, including small ORFs that give rise to human-specific and/or brain-specific microproteins, many of which we independently verified using proteomics. Ribosome profiling in stem-cell-derived human neuronal cultures corroborated these findings and revealed that several neuronal activity-induced non-coding RNAs encode previously undescribed microproteins. Physicochemical analysis of brain microproteins identified a class of proteins that contain arginine-glycine-glycine (RGG) repeats and, thus, may be regulators of RNA metabolism. This resource expands the known translational landscape of the human brain and illuminates previously unknown brain-specific protein products.

Uncommon Noninvasive Biomarkers for the Evaluation and Monitoring of the Etiopathogenesis of Alzheimer's Disease

Background:

Alzheimer´s disease (AD) is the most widespread dementia in the world, followed by vascular dementia. Since AD is a heterogeneous disease that shows several varied phenotypes, it is not easy to make an accurate diagnosis, so it arises when the symptoms are clear and the disease is already very advanced. Therefore, it is important to find out biomarkers for AD early diagnosis that facilitate treatment or slow down the disease. Classic biomarkers are obtained from cerebrospinal fluid and plasma, along with brain imaging by positron emission tomography. Attempts have been made to discover uncommon biomarkers from other body fluids, which are addressed in this update.

Objective:

This update aims to describe recent biomarkers from minimally invasive body fluids for the patients, such as saliva, urine, eye fluid or tears.

Methods:

Biomarkers were determined in patients versus controls by single tandem mass spectrometry, and immunoassays. Metabolites were identified by nuclear magnetic resonance, and microRNAs with genome-wide high-throughput real-time polymerase chain reaction-based platforms.

Results:

Biomarkers from urine, saliva, and eye fluid were described, including peptides/proteins, metabolites, and some microRNAs. The association with AD neuroinflammation and neurodegeneration was analyzed, highlighting the contribution of matrix metalloproteinases, the immune system and microglia, as well as the vascular system.

Conclusion:

Unusual biomarkers have been developed, which distinguish each stage and progression of the disease, and are suitable for the early AD diagnosis. An outstanding relationship of biomarkers with neuroinflammation and neurodegeneration was assessed, clearing up concerns of the etiopathogenesis of AD.