Brain Cortex Development Research Articles

The generation and properties of human cortical organoids as a disease model for malformations of cortical development.

As three-dimensional "organ-like" aggregates, human cortical organoids have emerged as powerful models for studying human brain evolution and brain disorders with unique advantages of human-specificity, fidelity and manipulation. Human cortical organoids derived from human pluripotent stem cells can elaborately replicate many of the key properties of human cortical development at the molecular, cellular, structural, and functional levels, including the anatomy, functional neural network, and interaction among different brain regions, thus facilitating the discovery of brain development and evolution. In addition to studying the neuro-electrophysiological features of brain cortex development, human cortical organoids have been widely used to mimic the pathophysiological features of cortical-related disease, especially in mimicking malformations of cortical development, thus revealing pathological mechanism and identifying effective drugs. In this review, we provide an overview of the generation of human cortical organoids and the properties of recapitulated cortical development and further outline their applications in modeling malformations of cortical development including pathological phenotype, underlying mechanisms and rescue strategies.

Sec3 exocyst component knockdown inhibits axonal formation and cortical neuronal migration during brain cortex development

Neurons are the largest known cells, with complex and highly polarized morphologies and consist of a cell body (soma), several dendrites, and a single axon. The establishment of polarity necessitates initial axonal outgrowth in concomitance with the addition of new membrane to the axon's plasmalemma. Axolemmal expansion occurs by exocytosis of plasmalemmal precursor vesicles primarily at the neuronal growth cone membrane. The multiprotein exocyst complex drives spatial location and specificity of vesicle fusion at plasma membrane. However, the specific participation of its different proteins on neuronal differentiation has not been fully established. In the present work we analyzed the role of Sec3, a prominent exocyst complex protein on neuronal differentiation. Using mice hippocampal primary cultures, we determined that Sec3 is expressed in neurons at early stages prior to neuronal polarization. Furthermore, we determined that silencing of Sec3 in mice hippocampal neurons in culture precluded polarization. Moreover, using in utero electroporation experiments, we determined that Sec3 knockdown affected cortical neurons migration and morphology during neocortex formation. Our results demonstrate that the exocyst complex protein Sec3 plays an important role in axon formation in neuronal differentiation and the migration of neuronal progenitors during cortex development.

Stress in the Educational System as a Potential Source of Epigenetic Influences on Children's Development and Behavior.

Despite current advances on the relevance of environmental cues and epigenetic mechanisms in biological processes, including behavior, little attention has been paid to the potential link between epigenetic influences and educational sciences. For instance, could the learning environment and stress determine epigenetic marking, affecting students' behavior development? Could this have consequences on educational outcomes? So far, it has been shown that environmental stress influences neurological processes and behavior both in humans and rats. Through epigenetic mechanisms, offspring from stressed individuals develop altered behavior without any exposure to traumatizing experiences. Methylated DNA and noncoding RNAs regulate neurological processes such as synaptic plasticity and brain cortex development in children. The malfunctioning of these processes is associated with several neurological disorders, and these findings open up new avenues for the design of enriched environments for education and therapy. In this article, we discuss current cases of stress and behavioral disorders found in youngsters, and highlight the importance of considering epigenetic processes affecting the development of cognitive abilities and learning within the educational environment and for the development of teaching methodologies.

Tubulin carboxypeptidase identity revealed

Cytoskeleton Enzymes of the α-tubulin detyrosination/tyrosination cycle create landmarks on microtubules that are essential for their multiple cellular functions and are altered in disease. Tubulin carboxypeptidases (TCPs) responsible for detyrosination have remained elusive for 40 years (see the Perspective by Akhmanova and Maiato). Aillaud et al. identified vasohibins as enzymes that perform the TCP function and found that their small interacting partner SBVP was essential for their activity. Vasohibin/SVBP complexes were involved in neuron polarization and brain cortex development. The authors also developed an inhibitor targeting this family of enzymes. Using a completely different strategy, Nieuwenhuis et al. also showed that vasohibins can remove the C-terminal tyrosine of α-tubulin. Science , this issue p. [1448][1], p. [1453][2]; see also p. [1381][3] [1]: /lookup/doi/10.1126/science.aao4165 [2]: /lookup/doi/10.1126/science.aao5676 [3]: /lookup/doi/10.1126/science.aar3895

Vasohibins encode tubulin detyrosinating activity.

Tubulin is subjected to a number of posttranslational modifications to generate heterogeneous microtubules. The modifications include removal and ligation of the C-terminal tyrosine of ⍺-tubulin. The enzymes responsible for detyrosination, an activity first observed 40 years ago, have remained elusive. We applied a genetic screen in haploid human cells to find regulators of tubulin detyrosination. We identified SVBP, a peptide that regulates the abundance of vasohibins (VASH1 and VASH2). Vasohibins, but not SVBP alone, increased detyrosination of ⍺-tubulin, and purified vasohibins removed the C-terminal tyrosine of ⍺-tubulin. We found that vasohibins play a cell type-dependent role in detyrosination, although cells also contain an additional detyrosinating activity. Thus, vasohibins, hitherto studied as secreted angiogenesis regulators, constitute a long-sought missing link in the tubulin tyrosination cycle.

Vasohibins/SVBP are tubulin carboxypeptidases (TCPs) that regulate neuron differentiation.

Reversible detyrosination of α-tubulin is crucial to microtubule dynamics and functions, and defects have been implicated in cancer, brain disorganization, and cardiomyopathies. The identity of the tubulin tyrosine carboxypeptidase (TCP) responsible for detyrosination has remained unclear. We used chemical proteomics with a potent irreversible inhibitor to show that the major brain TCP is a complex of vasohibin-1 (VASH1) with the small vasohibin binding protein (SVBP). VASH1 and its homolog VASH2, when complexed with SVBP, exhibited robust and specific Tyr/Phe carboxypeptidase activity on microtubules. Knockdown of vasohibins or SVBP and/or inhibitor addition in cultured neurons reduced detyrosinated α-tubulin levels and caused severe differentiation defects. Furthermore, knockdown of vasohibins disrupted neuronal migration in developing mouse neocortex. Thus, vasohibin/SVBP complexes represent long-sought TCP enzymes.

Nuclear Inositide Signaling Via Phospholipase C.

The existence of an independent nuclear inositide pathway distinct from the cytoplasmic one has been demonstrated in different physiological systems and in diseases. In this prospect we analyze the role of PI-PLCβ1 nuclear isoform in relation to the cell cycle regulation, the cell differentiation, and different physiopathological pathways focusing on the importance of the nuclear localization from both molecular and clinical point of view. PI-PLCβ1 is essential for G1/S transition through DAG and Cyclin D3 and plays also a central role in G2/M progression through Cyclin B1 and PKCα. In the differentiation process of C2C12 cells PI-PLCβ1 increases in both myogenic differentiation and osteogenic differentiation. PI-PLCβ1 and Cyclin D3 reduction has been observed in Myotonic Dystrophy (DM) suggesting a pivotal role of these enzymes in DM physiopathology. PI-PLCβ1 is also involved in adipogenesis through a double phase mechanism. Moreover, PI-PLCβ1 plays a key role in the normal hematopoietic differentiation where it seems to decrease in erythroid differentiation and increase in myeloid differentiation. In Myelodysplastic Syndromes (MDS) PI-PLCβ1 has a genetic and epigenetic relevance and it is related to MDS patients' risk of Acute Myeloid Leukemia (AML) evolution. In MDS patients PI-PLCβ1 seems to be also a therapeutic predictive outcome marker. In the central nervous system, PI-PLCβ1 seems to be involved in different pathways in both brain cortex development and synaptic plasticity related to different diseases. Another PI-PLC isozyme that could be related to nuclear activities is PI-PLCζ that is involved in infertility processes. J. Cell. Biochem. 118: 1969-1978, 2017. © 2017 Wiley Periodicals, Inc.

Reduced fetal brain fissures depth in fetuses with congenital heart diseases.

To screen and detect cortex gyration in fetuses with congenital heart disease (CHD) using Ultrasonography (US) during routine obstetric scans. The depth of the Sylvian fissure (SF), parieto-occipital fissure (POF), and calcarine (CF) fissure were prospectively serially measured and compared in 45 fetuses with CHD and 45 normal fetuses. Cardiac hemodynamic parameters, including aortic valve diameter (AV), pulmonary valve diameter (PV), velocity time integral of the aortic valve (VTIav), and velocity time integral of the pulmonary valve (VTIpv), were recorded. Correlations between the fissure depths and the prenatal cardiac hemodynamic parameters and postnatal neurodevelopmental scores were assessed. SF, POF, and CF were decreased in CHD fetuses compared with the controls in late of pregnancy (P < 0.01). The diagnostic category was independently associated with smaller fissure depths in fetuses with CHD (adjusted R2 = 0.472 for SF, 0.465 for POF, and 0.425 for CF). Correlations were observed between small fissure depths and decreased left heart hemodynamic parameters (AV and VTIav) in fetuses with CHD. The SF depth was positively correlated with the neurodevelopmental scores (P < 0.01). US can be used to screen for abnormal fetal brain cortex development during routine obstetric scans and to evaluate the maturation progress during close follow-up. © 2016 John Wiley & Sons, Ltd.

OP19.04: Assessment of the impact of prenatal colour Doppler on the brain cortex development in rats

OP19.04: Assessment of the impact of prenatal colour Doppler on the brain cortex development in rats

Expression profile of miRNA-29a in neural cells

Objective To investigate the expression profile of microRNA (miRNA)-29a in mice neural cells. Methods Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze miRNA-29a expression changes of neurons and astrocytes after 3, 7, 15, 21 d of primary culture in vitro, and cortex tissue of 3, 7, 15, 21 d old mice. Results miRNA-29a expression increased in nervous system with the growth of mice. Compared with the 3th day, miRNA-29a relative expression on the 7th, 15th, 21th days in neurons, astrocytes and cortex tissue were obviously higher ( P < 0.05 or P < 0.01). At each time point, the relative expression levels of miRNA-29a in cultured astrocytes were 20-40 times higher than in cultured neurons ( P = 0.000), and levels in cortex tissue were about 1/3 that seen in cultured astrocytes ( P = 0.000). Conclusions With the growth and development of brain cortex of mice, miRNA-29a is highly expressed in astrocytes, reflecting its abundant and specific expression. DOI: 10.3969/j.issn.1672-6731.2015.01.009

Plasma Membrane Density of GABAB-R1a, GABAB-R1b, GABA-R2 and Trimeric G-proteins in the Course of Postnatal Development of Rat Brain Cortex

With the aim to understand the onset of expression and developmental profile of plasma membrane (PM) content /density of crucial components of GABA(B)-R signaling cascade, GABA(B)-R1a, GABA(B)-R1b, GABA(B)-R2, G(i)1/G(i)2alpha, G(i)3alpha, G(o)alpha, G(z)alpha and Gbeta subunit proteins were determined by quantitative immunoblotting and compared in PM isolated from brain cortex of rats of different ages: between postnatal-day-1 (PD1) and 90 (PD90). PM density of GABA(B)-R1a, GABA(B)-R2, G(i)1/G(i)2alpha, G(i)3alpha, G(o)alpha, G(z)alpha and Gbeta was high already at birth and further development was reflected in parallel decrease of both GABA(B)-R1a and GABA(B)-R2 subunits. The major decrease of GABA(B)-R1a and GABA(B)-R2 occurred between the birth and PD15: to 55 % (R1a, **) and 51 % (R2, **), respectively. Contrarily, PM level of the cognate G-proteins G(i)1/G(i)2alpha, G(i)3alpha, G(o)alpha, G(z)alpha and Gbeta was unchanged in the course of the whole postnatal period of brain cortex development. Maturation of GABA(B)-R cascade was substantially different from ontogenetic profile of prototypical plasma membrane marker, Na, K-ATPase, which was low at birth and further development was reflected in continuous increase of PM density of this enzyme. Major change occurred between the birth and PD25. In adult rats, membrane content of Na, K-ATPase was 3-times higher than around the birth.

Ultrasonographic description of brain cortex and cingulate sulcus development in Mexican neonates and infants with congenital hypothyroidism

Ultrasonography of cortical and cingulum maturity patterns, were studied in newborns and infants with congenital hypothyroidism (CH). Transversal study of 29 newborns and infants with CH, detected by neonatal screening and confirmed with thyroid function test, thyroid ultrasonography, and thyroid scintigraphy. During the first 2 months of life, transfontanelar brain ultrasonography was performed. Brain cortex maturity was assessed by normality referents provided by Slagle and Timor methods. Cortical immaturity signs were observed in 69% of infants (20 patients with Slage's method brain cortex development delay (Pearson's p=0.05). Logistic nominal analysis for normality prediction demonstrated a correlation between brain cortex development and age, bone age, treatment duration, and type of CH. The most sensitive detecting technique was sagittal sight by Slagle's method. Brain cortex delayed development is frequent in children with CH. Bone age, postnatal age at treatment start, and time since treatment start, correlates with neurological development, but not athyreosis or sublingual nodule.

Structural Features and Chaperone Activity of the NudC Protein Family

The NudC family consists of four conserved proteins with representatives in all eukaryotes. The archetypal nudC gene from Aspergillus nidulans is a member of the nud gene family that is involved in the maintenance of nuclear migration. This family also includes nudF, whose human orthologue, Lis1, codes for a protein essential for brain cortex development. Three paralogues of NudC are known in vertebrates: NudC, NudC-like (NudCL), and NudC-like 2 (NudCL2). The fourth distantly related member of the family, CML66, contains a NudC-like domain. The three principal NudC proteins have no catalytic activity but appear to play as yet poorly defined roles in proliferating and dividing cells. We present crystallographic and NMR studies of the human NudC protein and discuss the results in the context of structures recently deposited by structural genomics centers (i.e., NudCL and mouse NudCL2). All proteins share the same core CS domain characteristic of proteins acting either as cochaperones of Hsp90 or as independent small heat shock proteins. However, while NudC and NudCL dimerize via an N-terminally located coiled coil, the smaller NudCL2 lacks this motif and instead dimerizes as a result of unique domain swapping. We show that NudC and NudCL, but not NudCL2, inhibit the aggregation of several target proteins, consistent with an Hsp90-independent heat shock protein function. Importantly, and in contrast to several previous reports, none of the three proteins is able to form binary complexes with Lis1. The availability of structural information will be of help in further studies on the cellular functions of the NudC family.

Identification of Differential Genes by Suppression Subtractive Hybridization: An Overview

INTRODUCTIONSuppression subtractive hybridization (SSH) is one of the most powerful and popular methods for generating subtracted cDNA or genomic DNA libraries. This technique can be used to compare two mRNA populations and obtain cDNAs representing genes that are either overexpressed or exclusively expressed in one population as compared to another. It can also be used for comparison of genomic DNA populations. We have used SSH in studies of regeneration and development on various types of model organisms (including freshwater planaria regeneration, Xenopus laevis development, and mammalian brain cortex development). We also use SSH for the analysis of strain-specific genes in bacteria with different characteristics. During these studies, a large number of differentially regulated and differentially presented genes have been identified, including transcriptional regulation factors and restriction modification enzymes. This article describes the SSH method and considerations for its use.