Gene regulatory landscape of cerebral cortex folding

Folding of the cerebral cortex is a key aspect of mammalian brain development and evolution, and defects are linked to severe neurological disorders. Primary folding occurs in highly stereotyped patterns that are predefined in the cortical germinal zones by a transcriptomic protomap. The gene regulatory landscape governing the emergence of this folding protomap remains unknown. We characterized the spatiotemporal dynamics of gene expression and active epigenetic landscape (H3K27ac) across prospective folds and fissures in ferret. Our results show that the transcriptomic protomap begins to emerge at early embryonic stages, and it involves cell-fate signaling pathways. The H3K27ac landscape reveals developmental cell-fate restriction and engages known developmental regulators, including the transcription factor Cux2. Manipulating Cux2 expression in cortical progenitors changed their proliferation and the folding pattern in ferret, caused by selective transcriptional changes as revealed by single-cell RNA sequencing analyses. Our findings highlight the key relevance of epigenetic mechanisms in defining the patterns of cerebral cortex folding.

Keep calm and make neurons: The effects of glucocorticoids on human cortical neurogenesis

Maternal well-being is important for the development of the fetus, with a key influence on its nervous system. In this issue of Neuron, Krontira et al.1 implicate glucocorticoids, the stress hormones, in the regulation of neural stem cell identity and proliferation, with long-lasting consequences on brain architecture and educational attainment.

Epi-regulate my brain: unlocking mechanisms of brain growth evolution

A new study sheds light on the mechanisms of cerebral cortex expansion during evolution.

Effectiveness of trauma-informed care interventions at the organizational level: A systematic review

Due to the recognition of the high prevalence and widespread effects of trauma, trauma-informed care (TIC) framework has emerged to address its impact and prevent retraumatization in the systems of care. Since organizational support has been identified as crucial in TIC implementation and sustainability, this systematic review assessed the status quo of TIC interventions which explicitly incorporate an organizational component. Our search yielded 880 articles, and 15 met the inclusion criteria. All the studies were carried out in the United States, more than half in mental health and Child Welfare Services, through longitudinal designs with no randomization or control group. All the studies utilized one to six organizational components, the most frequent related to presence of a defined leadership, procedures against retraumatization and provision of strength-based services. A wide variety of measures were used to assess the effectiveness of TIC interventions, with staff perceptions and safety management indicators being the most frequently used. In summary, the review indicates a positive trend in relation to the effectiveness of the interventions included in the study, with an improved functioning of beneficiaries, enhanced accessibility, and quality of services. However, the low quality and high heterogeneity of the studies make it difficult to draw conclusions with certainty. Therefore, the primary endeavor in TIC research is to provide more solid evidence. Partnerships between academic and community stakeholders will be of high value in this process. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Apparent regional differences in the spectrum of BARD1 pathogenic variants in Spanish population and importance of copy number variants

Only up to 25% of the cases in which there is a familial aggregation of breast and/or ovarian cancer are explained by germline mutations in the well-known BRCA1 and BRCA2 high-risk genes. Recently, the BRCA1-associated ring domain (BARD1), that partners BRCA1 in DNA repair, has been confirmed as a moderate-risk breast cancer susceptibility gene. Taking advantage of next-generation sequencing techniques, and with the purpose of defining the whole spectrum of possible pathogenic variants (PVs) in this gene, here we have performed a comprehensive mutational analysis of BARD1 in a cohort of 1946 Spanish patients who fulfilled criteria to be tested for germline pathogenic mutations in BRCA1 and BRCA2. We identified 22 different rare germline variants, being 5 of them clearly pathogenic or likely pathogenic large deletions, which account for 0.26% of the patients tested. Our results show that the prevalence and spectrum of mutations in the BARD1 gene might vary between different regions of Spain and expose the relevance to test for copy number variations.

Effects of acute iron overload on Nrf2-related glutathione metabolism in rat brain

Iron (Fe) overload triggers free radical production and lipid peroxidation processes that may lead to cell death (ferroptosis). The hypothesis of this work was that acute Fe-dextran treatment triggers Nrf2-mediated antioxidant regulation in rat brain involving glutathione (GSH) metabolism. Over the initial 8 h after Fe-dextran administration (single dose of 500 mg Fe-dextran/kg), total Fe, malondialdehyde (MDA) content, glutathione peroxidase (GPx), GPx-Se dependent (GPx-Se) and glutathione S-transferases (GST) activities were increased in rat whole brain. The content of GSH and the activity of glutathione reductase (GR) showed decreases (p < 0.05) after 6 and 8 h post injection in cortex. A significant increase in nuclear Nrf2 protein levels over control values was achieved after 6 h of Fe-dextran administration, while no significant differences were observed in the cytosolic fraction. Nuclear Nrf2/cytosolic Nrf2 ratios showed enhancement (p < 0.05) after 6 h of Fe overload, suggesting a greater translocation of the factor to the nucleus. No significant differences were observed in the expression of Keap1 in nuclear or cytosolic extracts. It is concluded that acute Fe overload induces oxidative stress in rat brain with the concomitant lipid peroxidation increase and GSH depletion, leading to the elevation of Nrf2-controlled GPx, GPx-Se and GST protein expression as a protective adaptive response. Further studies are required to fully comprehend the complex network of interrelated processes keeping the balance of GSH functions as chelator, antioxidant and redox buffer in the understanding of the ferroptotic and hormetic mechanisms triggered by Fe overload in brain.

MiRNAs in early brain development and pediatric cancer: At the intersection between healthy and diseased embryonic development

The size and organization of the brain are determined by the activity of progenitor cells early in development. Key mechanisms regulating progenitor cell biology involve miRNAs. These small noncoding RNA molecules bind mRNAs with high specificity, controlling their abundance and expression. The role of miRNAs in brain development has been studied extensively, but their involvement at early stages remained unknown until recently. Here, recent findings showing the important role of miRNAs in the earliest phases of brain development are reviewed, and it is discussed how loss of specific miRNAs leads to pathological conditions, particularly adult and pediatric brain tumors. Let-7 miRNA downregulation and the initiation of embryonal tumors with multilayered rosettes (ETMR), a novel link recently discovered by the laboratory, are focused upon. Finally, it is discussed how miRNAs may be used for the diagnosis and therapeutic treatment of pediatric brain tumors, with the hope of improving the prognosis of these devastating diseases.

Repression of Irs2 by let-7 miRNAs is essential for homeostasis of the telencephalic neuroepithelium

Structural integrity and cellular homeostasis of the embryonic stem cell niche are critical for normal tissue development. In the telencephalic neuroepithelium, this is controlled in part by cell adhesion molecules and regulators of progenitor cell lineage, but the specific orchestration of these processes remains unknown. Here, we studied the role of microRNAs in the embryonic telencephalon as key regulators of gene expression. By using the early recombiner Rx-Cre mouse, we identify novel and critical roles of miRNAs in early brain development, demonstrating they are essential to preserve the cellular homeostasis and structural integrity of the telencephalic neuroepithelium. We show that Rx-Cre;Dicer^F/F mouse embryos have a severe disruption of the telencephalic apical junction belt, followed by invagination of the ventricular surface and formation of hyperproliferative rosettes. Transcriptome analyses and functional experiments in vivo show that these defects result from upregulation of Irs2 upon loss of let-7 miRNAs in an apoptosis-independent manner. Our results reveal an unprecedented relevance of miRNAs in early forebrain development, with potential mechanistic implications in pediatric brain cancer.

The sugar transporter SWEET10 acts downstream of FLOWERING LOCUS T during floral transition of Arabidopsis thaliana

BACKGROUND

Floral transition initiates reproductive development of plants and occurs in response to environmental and endogenous signals. In Arabidopsis thaliana, this process is accelerated by several environmental cues, including exposure to long days. The photoperiod-dependent promotion of flowering involves the transcriptional induction of FLOWERING LOCUS T (FT) in the phloem of the leaf. FT encodes a mobile protein that is transported from the leaves to the shoot apical meristem, where it forms part of a regulatory complex that induces flowering. Whether FT also has biological functions in leaves of wild-type plants remains unclear.

RESULTS

In order to address this issue, we first studied the leaf transcriptomic changes associated with FT overexpression in the companion cells of the phloem. We found that FT induces the transcription of SWEET10, which encodes a bidirectional sucrose transporter, specifically in the leaf veins. Moreover, SWEET10 is transcriptionally activated by long photoperiods, and this activation depends on FT and one of its earliest target genes SUPPRESSOR OF CONSTANS OVEREXPRESSION 1 (SOC1). The ectopic expression of SWEET10 causes early flowering and leads to higher levels of transcription of flowering-time related genes in the shoot apex.

CONCLUSIONS

Collectively, our results suggest that the FT-signaling pathway activates the transcription of a sucrose uptake/efflux carrier during floral transition, indicating that it alters the metabolism of flowering plants as well as reprogramming the transcription of floral regulators in the shoot meristem.

Arabidopsis EMSY-like (EML) histone readers are necessary for post-fertilization seed development, but prevent fertilization-independent seed formation

Seed development is a complex regulatory process that includes a transition from gametophytic to sporophytic program. The synchronized development of different seed compartments (seed coat, endosperm and embryo) depends on a balance in parental genome contributions. In the most severe cases, the disruption of the balance leads to seed abortion. This represents one of the main obstacles for the engineering of asexual reproduction through seeds (apomixis), and for generating new interspecies hybrids. The repression of auxin synthesis by the Polycomb Repressive Complex 2 (PRC2) is a major mechanism contributing to sensing genome balance. However, current efforts focusing on decreasing PRC2 or elevating auxin levels have not yet resulted in the production of apomictic seed. Here, we show that EMSY-Like Tudor/Agenet H3K36me3 histone readers EML1 and EML3 are necessary for early stages of seed development to proceed at a normal rate in Arabidopsis. We further demonstrate that both EML1 and EML3 are required to prevent the initiation of seed development in the absence of fertilization. Based on the whole genome expression analysis, we identify auxin transport and signaling genes as the most enriched downstream targets of EML1 and EML3. We hypothesize that EML1 and EML3 function to repress and soften paternal gene expression by fine-tuning auxin responses. Discovery of this pathway may contribute to the engineering of apomixis and interspecies hybrids.

High prevalence of non-alcoholic fatty liver disease among hidradenitis suppurativa patients independent of classic metabolic risk factors

BACKGROUND

Some chronic inflammatory skin diseases, such as psoriasis, have been associated with an increased prevalence of non-alcoholic fatty liver disease (NAFLD). Nevertheless, this prevalence in hidradenitis suppurativa (HS) has not been assessed to date.

OBJECTIVES

To determine the prevalence of NAFLD in patients with HS and the risk factors associated with this disorder.

METHODS

This case-control study enrolled 70 HS patients and 150 age- and gender-matched controls who were evaluated by hepatic ultrasonography (US) and transient elastography (TE) after excluding other secondary causes of chronic liver disease. The diagnosis of NAFLD was established if US and/or TE were altered.

RESULTS

The prevalence of NAFLD was significantly increased in patients with HS compared to controls (72.9% vs. 24.7%: P < 0.001). In the multivariable regression model adjusted for age, sex and classic metabolic risk factors for NAFLD, HS was significantly and independently associated with the presence of NAFLD [OR 7.75 confidence interval (CI) 2.54-23.64; P < 0.001].

CONCLUSIONS

Our results show a high prevalence of NAFLD in HS patients independent of classic metabolic risk factors. Therefore, we suggest HS patients to be evaluated for NAFLD and managed accordingly.

Docosahexaenoic acid-thyroid hormone combined protocol as a novel approach to metabolic stress disorders: Relation to mitochondrial adaptation via liver PGC-1α and sirtuin1 activation

Docosahexaenoic acid (DHA) and 3,3',5-triiodothyronine (T₃ ) combined protocol affords protection against liver injury via AMPK signaling supporting energy requirements. The aim of this work was to test the hypothesis that a DHA + T₃ accomplish mitochondrial adaptation through downstream upregulation of PPAR-γ coactivator 1α (PGC-1α). Male Sprague-Dawley rats were given daily oral doses of 300 mg DHA/kg or saline (controls) for three consecutive days, followed by 0.05 mg T₃ /kg (or hormone vehicle) ip at the fourth day, or single dose of 0.1 mg T₃ /kg alone. Liver mRNA levels were assayed by qPCR, NAD⁺ /NADH ratios, hepatic proteins, histone 3 acetylation and serum T₃ and β-hydroxybutyrate levels were determined by specific ELISA kits. Combined DHA + T₃ protocol led to increased liver AMPK, PGC-1α, NRF-2, COX-IV, and β-ATP synthase mRNAs, with concomitant higher protein levels of COX-IV and NRF-2, 369% enhancement in the NAD⁺ /NADH ratio, 47% decrease in histone 3 acetylation and 162% increase in serum levels of β-hydroxybutyrate over control values. These changes were reproduced by the higher dose of T₃ without major alterations by DHA or T₃ alone. In conclusion, liver mitochondrial adaptation by DHA + T₃ is associated with PGC-1α upregulation involving enhanced transcription of the coactivator, which may be contributed by PGC-1α deacetylation and phosphorylation by SIRT1 and AMPK activation, respectively. This contention is supported by NRF-2-dependent enhancement in COX-1 and β-ATP synthase induction with higher fatty acid oxidation resulting in a significant ketogenic response, which may represent a suitable strategy for hepatic steatosis with future clinical applications. © 2018 BioFactors, 45(2):271-278, 2019.

Extensive branching of radially-migrating neurons in the mammalian cerebral cortex

Excitatory neurons of the cerebral cortex migrate radially from their place of birth to their final position in the cortical plate during development. Radially-migrating neurons display a single leading process that establishes the direction of movement. This leading process has been described as being unbranched, and the occurrence of branches proposed to impair radial migration. Here we have analyzed the detailed morphology of leading process in radially-migrating pyramidal neurons and its impact on radial migration. We have compared ferret and mouse to identify differences between cortices that undergo folding or not. In mouse, we find that half of radially-migrating neurons exhibit a branched leading process, this being even more frequent in ferret. Branched leading processes are less parallel to radial glia fibers than those unbranched, suggesting some independence from radial glia fibers. Two-photon videomicroscopy revealed that a vast majority of neurons branch their leading process at some point during radial migration, but this does not reduce their migration speed. We have tested the functional impact of exuberant leading process branching by expressing a dominant negative Cdk5. We confirm that loss of Cdk5 function significantly impairs radial migration, but this is independent from increased branching of the leading process. We propose that excitatory neurons may branch their leading process as an evolutionary mechanism to allow cells changing their trajectory of migration to disperse laterally, such that increased branching in gyrencephalic species favors the tangential dispersion of radially-migrating neurons, and cortical folding.

Arabidopsis thaliana ambient temperature responsive lncRNAs

BACKGROUND

Long non-coding RNAs (lncRNAs) have emerged as new class of regulatory molecules in animals where they regulate gene expression at transcriptional and post-transcriptional level. Recent studies also identified lncRNAs in plant genomes, revealing a new level of transcriptional complexity in plants. Thousands of lncRNAs have been predicted in the Arabidopsis thaliana genome, but only a few have been studied in depth.

RESULTS

Here we report the identification of Arabidopsis lncRNAs that are expressed during the vegetative stage of development in either the shoot apical meristem or in leaves. We found that hundreds of lncRNAs are expressed in these tissues, of which 50 show differential expression upon an increase in ambient temperature. One of these lncRNAs, FLINC, is down-regulated at higher ambient temperature and affects ambient temperature-mediated flowering in Arabidopsis.

CONCLUSION

A number of ambient temperature responsive lncRNAs were identified with potential roles in the regulation of temperature-dependent developmental changes, such as the transition from the vegetative to the reproductive (flowering) phase. The challenge for the future is to characterize the biological function and molecular mode of action of the large number of ambient temperature-regulated lncRNAs that have been identified in this study.

Thyroid Hormone-Induced Expression of the Hepatic Scaffold Proteins Sestrin2, β-Klotho, and FRS2α in Relation to FGF21-AMPK Signaling

Thyroid hormone (3,3',5-triiodothyronine, T₃) accelerates energy metabolism in the liver through mechanisms involving upregulation of AMP-activated protein kinase (AMPK). This study aims to assess the influence of T₃ on the expression of the scaffold proteins β-Klotho, fibroblast growth factor receptor substrate 2α (FRS2α), and Sestrin2 in relation to FGF21-AMPK signaling. Male Sprague-Dawley rats were given 0.1 mg T₃/kg or hormone vehicle (controls) and studies were done 24 h after treatment. These include measurements of the mRNA expression (qPCR) of hepatic β-Klotho, FGF21, FGF21 receptor-1 (FGFR1), extracellular-signal-regulated kinase 1/2 (ERK1/2), FRS2α, ribosomal S6 kinase-1 (RSK1), liver kinase B1 (LKB1), AMPK, and Sestrin2. Also, protein levels of FGF21, FGFR1 (ELISA), and ERK1/2 (Western blot) were measured. T₃ elicited a calorigenic response with higher hepatic mRNA expression of β-Klotho, FRS2α, and FGF21, increased serum FGF21, without changes in liver FGFR1 mRNA and its plasma levels. In addition, T₃ enhanced ERK1/2 phosphorylation and the mRNA expression of ERK1/2, RSK1, LKB1, AMPK, and Sestrin2. T₃ administration enhances liver FGF21-AMPK signaling involving upregulation of the scaffold proteins β-Klotho, FRS2α, and Sestrin2. β-Klotho and FRS2 induction favours the operation of the FGF21-FGFR1-β-Klotho complex as evidenced by the enhancement in ERK1/2 phosphorylation, whereas that of Sestrin2 recruits LKB1 to achieved AMPK activation, thus supporting a higher energy expenditure condition that may be desirable in some metabolic disorders.

PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

Seasonal reproduction in many organisms requires detection of day length. This is achieved by integrating information on the light environment with an internal photoperiodic time-keeping mechanism. Arabidopsis thaliana promotes flowering in response to long days (LDs), and CONSTANS (CO) transcription factor represents a photoperiodic timer whose stability is higher when plants are exposed to light under LDs. Here, we show that PSEUDO RESPONSE REGULATOR (PRR) proteins directly mediate this stabilization. PRRs interact with and stabilize CO at specific times during the day, thereby mediating its accumulation under LDs. PRR-mediated stabilization increases binding of CO to the promoter of FLOWERING LOCUS T (FT), leading to enhanced FT transcription and early flowering under these conditions. PRRs were previously reported to contribute to timekeeping by regulating CO transcription through their roles in the circadian clock. We propose an additional role for PRRs in which they act upon CO protein to promote flowering, directly coupling information on light exposure to the timekeeper and allowing recognition of LDs.

Upregulation of rat liver PPARα-FGF21 signaling by a docosahexaenoic acid and thyroid hormone combined protocol

Prevention of ischemia-reperfusion liver injury is achieved by a combined omega-3 and thyroid hormone (T₃ ) protocol, which may involve peroxisome-proliferator activated receptor-α (PPAR-α)-fibroblast growth factor 21 (FGF21) signaling supporting energy requirements. Combined docosahexaenoic acid (DHA; daily doses of 300 mg/kg for 3 days) plus 0.05 mg T₃ /kg given to fed rats elicited higher hepatic DHA contents and serum T₃ levels, increased PPAR-α mRNA and its DNA binding, with higher mRNA expression of the PPAR-α target genes for carnitine-palmitoyl transferase 1α, acyl-CoA oxidase, and 3-hydroxyl-3-methylglutaryl-CoA synthase 2, effects that were mimicked by 0.1 mg T₃ /kg given alone or by the PPAR-α agonist WY-14632. Under these conditions, the mRNA expression of retinoic X receptor-α (RXR-α) is also increased, with concomitant elevation of the hepatic mRNA and protein FGF21 levels and those of serum FGF21. It is concluded that PPAR-α-FGF21 induction by DHA combined with T₃ may involve ligand activation of PPAR-α by DHA and enhanced expression of PPAR-α by T₃ , with consequent upregulation of the FGF21 that is controlled by PPAR-α. Considering the beneficial effects of PPAR-α-FGF21 signaling on carbohydrate and lipid metabolism, further investigations are required to clarify its potential therapeutic applications in human metabolic disorders. © 2016 BioFactors, 42(6):638-646, 2016.

Rio de la Plata and its Maritime Front Environmental Information System and Portal: tools used and lessons learned

Paper presented at the Sixth Water Information Summit: Breaking The Barriers Let Water Information Flow! Waterweb Consortium and IRC International Water and Sanitation Centre September 9-12 Delft, The Netherlands 2003. Describes the aims, development and functions of the Integrated Information System of the FREPLATA Project and the creation of the Rio de la Plata and its Maritime Front Portal, a cooperative Internet gateway to environmental and spatial information on the Rio de Plata region. The FREPLATA project is a cooperative activity of 18 institutions in Argentina and Uruguay. The Project and institutions with suitably trained personnel designed, developed and implemented databases, applications and standards which enable the systematization of information and constitute tools for management and decision-making.

Photoperiodic and thermosensory pathways interact through CONSTANS to promote flowering at high temperature under short days

Plants detect changes in day length to induce seasonal patterns of flowering. The photoperiodic pathway accelerates the flowering of Arabidopsis thaliana under long days (LDs) whereas it is inactive under short days (SDs), resulting in delayed flowering. This delay is overcome by exposure of plants to high temperature (27°C) under SDs (27°C-SD). Previously, the high-temperature flowering response was proposed to involve either the impaired activity of MADS-box transcription factor (TF) floral repressors or PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) TF-mediated activation of FLOWERING LOCUS T (FT), which encodes the output signal of the photoperiodic pathway. We integrate these observations by studying several PIFs, the MADS-box SHORT VEGETATIVE PHASE (SVP) and the photoperiodic pathway under 27°C-SD. We find that the mRNAs of FT and its paralogue TWIN SISTER OF FT (TSF) are increased at dusk under 27°C-SD compared with 21°C-SD, and that this requires PIF4 and PIF5 as well as CONSTANS (CO), a TF that promotes flowering under LDs. The CO and PIF4 proteins are present at dusk under 27°C-SD, and they physically interact. Although Col-0 plants flower at similar times under 27°C-SD and 21°C-LD the expression level of FT is approximately 10-fold higher under 21°C-LD, suggesting that responsiveness to FT is also increased under 27°C-SD, perhaps as a result of the reduced activity of SVP in the meristem. Accordingly, only svp-41 ft-10 tsf-1 plants flowered at the same time under 21°C-SD and 27°C-SD. Thus, we propose that under non-inductive SDs, elevated temperatures increase the activity and sensitize the response to the photoperiod pathway.

Cerebral cortex expansion and folding: what have we learned?

One of the most prominent features of the human brain is the fabulous size of the cerebral cortex and its intricate folding. Cortical folding takes place during embryonic development and is important to optimize the functional organization and wiring of the brain, as well as to allow fitting a large cortex in a limited cranial volume. Pathological alterations in size or folding of the human cortex lead to severe intellectual disability and intractable epilepsy. Hence, cortical expansion and folding are viewed as key processes in mammalian brain development and evolution, ultimately leading to increased intellectual performance and, eventually, to the emergence of human cognition. Here, we provide an overview and discuss some of the most significant advances in our understanding of cortical expansion and folding over the last decades. These include discoveries in multiple and diverse disciplines, from cellular and molecular mechanisms regulating cortical development and neurogenesis, genetic mechanisms defining the patterns of cortical folds, the biomechanics of cortical growth and buckling, lessons from human disease, and how genetic evolution steered cortical size and folding during mammalian evolution.