Early specification of ascidian larval motor neurons

AbstractIn the tadpole larvae of the ascidian Halocynthia roretzi, six motor neurons, Moto-A, -B, and -C (a pair of each), are localized proximal to the caudal neural tube and show distinct morphology and innervation patterns. To gain insights into early mechanisms underlying differentiation of individual motor neurons, we have isolated an ascidian homologue of Islet, a LIM type homeobox gene. Earliest expression of Islet was detected in a pair of bilateral blastomeres on the dorsal edge of the late gastrula. At the neurula stage, this expression began to disappear and more posterior cells started to express Islet. Compared to expression of a series of motor neuron genes, it was confirmed that early Islet-positive blastomeres are the common precursors of Moto-A and -B, and late Islet-positive cells in the posterior neural tube are the precursors of Moto-C. Overexpression of Islet induced ectopic expression of motor neuron markers, suggesting that Islet is capable of regulating motor neuron differentiation. Since early expression of Islet colocalizes with that of HrBMPb, the ascidian homologue of BMP2/4, we tested a role of BMP in specification of the motor neuron fate. Overexpression of HrBMPb led to expansion of Lim and Islet expression toward the central area of the neural plate, and microinjection of mRNA coding for a dominant-negative BMP receptor weakened the expression of these genes. Our results suggest that determination of the ascidian motor neuron fate takes place at late gastrula stage and local BMP signaling may play a role in this step

ニューロン ノ ゲノム ノ タヨウセイ

組織の再生が極めて限定的な脳では、胎生期から出生後の早い時期にかけて産生された1つ1つのニューロンは個体の生涯を通じて神経ネットワークの中で機能し続ける。脳は膨大かつ多様なニューロンから成っており、一つとして同じ形態や機能を持つニューロンは存在しない。ニューロンではゲノムにも多様性が報告されてきた。染色体数の異常とゲノムDNA配列の突然変異に加え、ニューロンの多様性を作るためのゲノムの積極的な再構成もある。発生期にゲノム異常を持ったニューロンが多く生じるが、それ以降にもニューロンのゲノムは常に不安定な状態にある。そのため脳内でニューロンがゲノムの観点からモザイク状であることは一般的である。複雑な脳機能を担うニューロンにとってゲノムの多様性は重要であり、ヒトでは個性などを生じる原因と考えられる。一方で脳の発生やニューロンの機能に関わる遺伝子に起こるde novo変異が神経発達障害や神経変性症に関与していることが示唆されている。脳では少数もしくは1集団のニューロンに起こるde novo変異でもネットワーク全体の機能に影響を与える可能性があり、近年では脳に起こるde novo変異と神経発達障害の関連が大規模なゲノム解析によって調査されている。個々のニューロンに起きるゲノム変異の広汎な調査によって、神経発達障害や神経変性症の孤発性発症の原因が明らかになることが期待される。Because tissue regeneration is highly restricted in the human brain, the neurons born in the fetal and neonatal periods have extreme longevity. The brain is consisted of huge number of various neurons. Variations in the neuron have been reported in its genome. Such variations include microscopic abnormalities of chromosomes, copy number variations, and single nucleotide mutations. Addition to these, developmentally regulated DNA sequence rearrangements were also reported. During early stage of the brain development, rapid production of neurons causes accidental abnormalities in chromosomes and genome sequence frequently. Mutations in the neuronal genome occur in the mature brain. Thus, generally the brain exhibits variation in the neuronal genome. This mosaicism is suggested to be important for complicated brain functions and contribute to differences of individuals, such as personalities and health indices. Because it is possible that a mutation in the genome of one neuron or a group of neurons affects neuronal network functions, large scale investigations of de novo mutations in the brain are ongoing recently. These efforts are expected to find relationships between variations in the genome of neurons and sporadic neurodevelopmental and neurodegenerative disorders

ニューロン ノ ゲノムインテグリティ

ニューロンのゲノムは脳神経機能によるストレスに強くさらされており不安定である。ゲノムDNAの修復が不十分な場合に生じる変異は、様々な神経発達障害や神経変性疾患の原因となりうる。ニューロンのゲノムDNAの損傷はニューロン産生期と脳機能を担う段階の両時期において外的要因のみならず生理的機能によっても誘導される。ニューロンは発生の限られた時期に大量に生み出され神経幹細胞および神経前駆細胞では急速な細胞分裂を行う。そのためDNA複製にエラーが生じ、ニューロンに染色体異常などが起こりうる。分化し神経ネットワーク内で機能を獲得したニューロンは電気的興奮や遺伝子発現変化など代謝が盛んであり、このようなニューロンの正常な活動は、自発的な二本鎖切断などの損傷を起こしたDNAが修復されることで維持される。このようなゲノムのDNA配列や構造の維持はゲノムインテグリティと呼ばれる。神経活動によって不安定になるニューロンのゲノムインテグリティにはより強力なDNA修復機構が働いていると考えられる。本総説では、ニューロンのゲノムインテグリティとその破綻の神経疾患への関与についての最近の研究の進歩を述べる。Genome DNA of neurons in the brain is unstable, and mutations caused by inaccurate repair of the genomic DNA of neurons can causative of neurodevelopmental and neurodegenerative disorders. Damages to the neuronal genome are induced exogenously and endogenously. Rapid cell proliferation of the neural stem cells during embryonic and fetal brain development can lead to errors in genome duplication causing chromosomal aberrations. Neurons that have acquired function in the neural network are metabolically active through their electrical excitation and gene expression changes. Such neuronal activities involve repairs of damaged DNA, such as spontaneous double-strand breaks. Maintenance of the DNA sequence and genomic structure are called genome integrity. For neuronal genome integrity against unstable conditions of the genome caused by neural activity, it is likely that intense molecular mechanisms preserve the genome for healthy neuronal functions. In this review, we describe recent progress in understanding of the genome integrity in functional neurons referring to their disruptions reported in neurological diseases.departmental bulletin pape

Bioactive Hydroperoxyl Cembranoids from the Red Sea Soft Coral Sarcophyton glaucum

A chemical investigation of an ethyl acetate extract of the Red Sea soft coral Sarcophyton glaucum has led to the isolation of two peroxide diterpenes, 11(S) hydroperoxylsarcoph-12(20)-ene (1), and 12(S)-hydroperoxylsarcoph-10-ene (2), as well as 8-epi-sarcophinone (3). In addition to these three new compounds, two known structures were identified including: ent-sarcophine (4) and sarcophine (5). Structures were elucidated by spectroscopic analysis, with the relative configuration of 1 and 2 confirmed by X-ray diffraction. Isolated compounds were found to be inhibitors of cytochrome P450 1A activity as well as inducers of glutathione S-transferases (GST), quinone reductase (QR), and epoxide hydrolase (mEH) establishing chemo-preventive and tumor anti-initiating activity for these characterized metabolites

Allele Polymorphism and Haplotype Diversity of HLA-A, -B and -DRB1 Loci in Sequence-Based Typing for Chinese Uyghur Ethnic Group

Previous studies indicate that the frequency distributions of HLA alleles and haplotypes vary from one ethnic group to another or between the members of the same ethnic group living in different geographic areas. It is necessary and meaningful to study the high-resolution allelic and haplotypic distributions of HLA loci in different groups.High-resolution HLA typing for the Uyghur ethnic minority group using polymerase chain reaction-sequence-based-typing method was first reported. HLA-A, -B and -DRB1 allelic distributions were determined in 104 unrelated healthy Uyghur individuals and haplotypic frequencies and linkage disequilibrium parameters for HLA loci were estimated using the maximum-likelihood method. A total of 35 HLA-A, 51 HLA-B and 33 HLA-DRB1 alleles were identified at the four-digit level in the population. High frequency alleles were HLA-A*1101 (13.46%), A*0201 (12.50%), A*0301 (10.10%); HLA-B*5101(8.17%), B*3501(6.73%), B*5001 (6.25%); HLA-DRB1*0701 (16.35%), DRB1*1501 (8.65%) and DRB1*0301 (7.69%). The two-locus haplotypes at the highest frequency were HLA-A*3001-B*1302 (2.88%), A*2402-B*5101 (2.86%); HLA-B*5001-DRB1*0701 (4.14%) and B*0702-DRB1*1501 (3.37%). The three-locus haplotype at the highest frequency was HLA-A*3001-B*1302-DRB1*0701(2.40%). Significantly high linkage disequilibrium was observed in six two-locus haplotypes, with their corresponding relative linkage disequilibrium parameters equal to 1. Neighbor-joining phylogenetic tree between the Uyghur group and other previously reported populations was constructed on the basis of standard genetic distances among the populations calculated using the four-digit sequence-level allelic frequencies at HLA-A, HLA-B and HLA-DRB1 loci. The phylogenetic analyses reveal that the Uyghur group belongs to the northwestern Chinese populations and is most closely related to the Xibe group, and then to Kirgiz, Hui, Mongolian and Northern Han.The present findings could be useful to elucidate the genetic background of the population and to provide valuable data for HLA matching in clinical bone marrow transplantation, HLA-linked disease-association studies, population genetics, human identification and paternity tests in forensic sciences

Immunosuppressive Treatment for an anti-U1 Ribonucleoprotein Antibody-positive Patient with Pulmonary Arterial Hypertension

A 34-year-old woman with pulmonary arterial hypertension (PAH) was admitted to the hospital. She had been diagnosed with PAH three years earlier and treated with triple vasodilator therapy. She was positive for anti-U1 ribonucleoprotein antibodies but did not show any other symptoms associated with autoimmune diseases. Corticosteroid and cyclophosphamide therapy was administered, suspecting the involvement of immunological pathophysiology. After 3 weeks, the mean pulmonary artery pressure decreased from 50 to 38 mmHg without any change in the vasodilators. Immunosuppressive therapy was effective in this patient with PAH with an anti-U1 ribonucleoprotein-antibody-positive response and might be an option for patients with these specific features

Subcortically and Callosally Projecting Neurons are Distinct Neuronal Pools in the Motor Cortex of the Reeler Mouse

Subcortically projecting neurons and callosally projecting ones are distinct neuronal pools in the cerebral cortex of the rodents. However, cortical efferent neurons are known to project multiple targets transiently by plural collateral axons. These plural axons are eliminated during prenatal and postnatal development. In the cerebral cortex of the Reelin-deficient mouse, reeler, which is caused by mutation of the reelin gene, cortical efferent neurons are ectopically distributed. However, it is still unknown whether cortical efferent neurons in the reeler mouse lose surplus collateral axons or maintain them during developmental periods. If surplus collaterals of malpositioned cortical neurons are not eliminated, neurons projecting subcortically may project their axons to the contralateral hemisphere. To test this plausible hypothesis, we made double injections of two fluorescent dyes, Fast Blue and Diamidino yellow dihydrochloride into two of three regions, i.e., upper cervical cord, ventral lateral thalamic nucleus, and contralateral motor cortex of the normal and reeler mice, to label corticospinal, corticothalamic and callosal commissure neurons in the motor cortex, retrogradely. No double labeled neurons were identified in the motor cortex of the normal and reeler mice, although the distribution patterns of these cortical efferent neurons were completely different between normal and reeler mice. These findings strongly suggest that collateral elimination of cortical efferent neurons during developing periods are not affected in this mutant mouse

Immunohistochemical Expression Pattern of FGFR1, FGFR2, RIP5, and HIP2 in Developing and Postnatal Kidneys of Dab1−/− (yotari) Mice

This study aimed to explore how Dab1 gene functional silencing influences the spatial and temporal expression patterns of fibroblast growth factor receptor 1 (FGFR1), fibroblast growth factor receptor 2 (FGFR2), receptor-interacting protein kinase 5 (RIP5), and huntingtin-interacting protein 2 (HIP2) in the developing and postnatal kidneys of the yotari mice as potential determinants of normal kidney formation and function. Dab1−/− animal kidneys exhibit diminished FGFR1/FGFR2 expression in all examined developmental stages, whereas RIP5 cell immunoreactivity demonstrated negligible variation. The HIP2 expression revealed a discernible difference during the postnatal period, where we noted a significant decrease in almost all the observed kidney structures of yotari animals. An extracellular signal-regulated kinase (Erk1/2) and mammalian target of rapamycin (mTOR) expression in yotari kidneys decreased in embryonic and postnatal developmental phases for which we can hypothesize that the Erk1/2 signaling pathway in the yotari mice kidneys is dependent on Reelin with Dab1 only partially implicated in Reelin-mediated MEK/Erk1/2 activation. The impairment of FGFR1 and FGFR2 expression suggests the involvement of the observed markers in generating the CAKUT phenotype resulting in renal hypoplasia. Our study demonstrates the critical role of HIP2 in reducing cell death throughout nephrogenesis and maturation in wild-type mice and indicates a possible connection between decreased HIP2 expression in postnatal kidney structures and observed podocyte injury in yotari. Our results emphasize the crucial function of the examined markers throughout normal kidney development and their potential participation in kidney pathology and diagnostics, where they might serve as biomarkers and therapeutic targets