Frameshift PQBP-1 mutants K192Sfs*7 and R153Sfs*41 implicated in X-linked intellectual disability form stable dimers.

Polyglutamine tract-binding protein-1 (PQBP-1) is a nuclear intrinsically disordered protein playing important roles in transcriptional regulation and RNA splicing during embryonic and postembryonic development. In human, its mutations lead to severe cognitive impairment known as the Renpenning syndrome, a form of X-linked intellectual disability (XLID). Here, we report a combined biophysical study of two PQBP-1 frameshift mutants, K192Sfs*7 and R153Sfs*41. Both mutants are dimeric in solution, in contrast to the monomeric wild-type protein. These mutants contain more folded contents and have increased thermal stabilities. Using small-angle X-ray scattering data, we generated three-dimensional envelopes which revealed their overall flat shapes. We also described each mutant using an ensemble model based on a native-like initial pool with a dimeric structural core. PQBP-1 is known to repress transcription by way of interacting with the C-terminal domain of RNA polymerase II, which consists of 52 repeats of a consensus heptapeptide sequence YSPTSPS. We studied the binding of PQBP-1 variants to the labelled peptide which is phosphorylated at positions 2 and 5 (YpSPTpSPS) and found that this interaction is significantly weakened in the two mutants

Dopaminergic stimulation up-regulates the in vivo expression of brain-derived neurotrophic factor (BDNF) in the striatum

AbstractWe investigated the effect of dopamine on the in vivo expression of brain-derived neurotrophic factor (BDNF) in the striatum of mouse. BDNF mRNA expression in the striation, which was Quantified with the reverse transcriptase polymerase chain reaction, was up-repulated from 2 h after oral administration of levodopa, a precursor of dopamine. The increase was sustained for 16 h. Co-administrstion of haloperidol partially inhibited dopamine-induced BDNF enhancement. These data suggest that dopaminergic stimulation directly promotes the expression of BDNF in the striatum in vivo

Glial Cell Lineage Expression of Mutant Ataxin-1 and Huntingtin Induces Developmental and Late-Onset Neuronal Pathologies in Drosophila Models

In several neurodegenerative disorders, toxic effects of glial cells on neurons are implicated. However the generality of the non-cell autonomous pathologies derived from glial cells has not been established, and the specificity among different neurodegenerative disorders remains unknown.We newly generated Drosophila models expressing human mutant huntingtin (hHtt103Q) or ataxin-1 (hAtx1-82Q) in the glial cell lineage at different stages of differentiation, and analyzed their morphological and behavioral phenotypes. To express hHtt103Q and hAtx1-82Q, we used 2 different Gal4 drivers, gcm-Gal4 and repo-Gal4. Gcm-Gal4 is known to be a neuroglioblast/glioblast-specific driver whose effect is limited to development. Repo-Gal4 is known to be a pan-glial driver and the expression starts at glioblasts and continues after terminal differentiation. Gcm-Gal4-induced hHtt103Q was more toxic than repo-Gal4-induced hHtt103Q from the aspects of development, locomotive activity and survival of flies. When hAtx1-82Q was expressed by gcm- or repo-Gal4 driver, no fly became adult. Interestingly, the head and brain sizes were markedly reduced in a part of pupae expressing hAtx1-82Q under the control of gcm-Gal4, and these pupae showed extreme destruction of the brain structure. The other pupae expressing hAtx1-82Q also showed brain shrinkage and abnormal connections of neurons. These results suggested that expression of polyQ proteins in neuroglioblasts provided a remarkable effect on the developmental and adult brains, and that glial cell lineage expression of hAtx1-82Q was more toxic than that of hHtt103Q in our assays.All these studies suggested that the non-cell autonomous effect of glial cells might be a common pathology shared by multiple neurodegenerative disorders. In addition, the fly models would be available for analyzing molecular pathologies and developing novel therapeutics against the non-cell autonomous polyQ pathology. In conclusion, our novel fly models have extended the non-cell autonomous pathology hypothesis as well as the developmental effect hypothesis to multiple polyQ diseases. The two pathologies might be generally shared in neurodegeneration

Disassembly of Shank and Homer Synaptic Clusters Is Driven by Soluble β-Amyloid1-40 through Divergent NMDAR-Dependent Signalling Pathways

Disruption of the postsynaptic density (PSD), a network of scaffold proteins located in dendritic spines, is thought to be responsible for synaptic dysfunction and loss in early-stage Alzheimer's disease (AD). Extending our previous demonstration that derangement of the PSD by soluble amyloid-β (Aβ) involves proteasomal degradation of PSD-95, a protein important for ionotropic glutamate receptor trafficking, we now show that Aβ also disrupts two other scaffold proteins, Homer1b and Shank1, that couple PSD-95 with ionotropic and metabotropic glutamate receptors. Treatment of fronto-cortical neurons with soluble Aβ results in rapid (within 1 h) and significant thinning of the PSD, decreased synaptic levels of Homer1b and Shank1, and reduced synaptic mGluR1 levels. We show that de novo protein synthesis is required for the declustering effects of Aβ on Homer1b (but not Shank1) and that, in contrast to PSD-95, Aβ-induced Homer1b and Shank1 cluster disassembly does not depend on proteasome activity. The regulation of Homer1b and Shank1 by Aβ diverges in two other respects: i) whereas the activity of both NMDAR and VDCC is required for Aβ-induced declustering of Homer1b, Aβ-induced declustering of Shank1 only requires NMDAR activity; and ii) whereas the effects of Aβ on Homer1b involve engagement of the PI-3K pathway and calcineurin phosphatase (PP2B) activity, those on Shank1 involve activation of the ERK pathway. In summary, soluble Aβ recruits discrete signalling pathways to rapidly reduce the synaptic localization of major components of the PSD and to regulate the availability of mGluR1 in the synapse

Formation of Polyglutamine Inclusions in a Wide Range of Non-CNS Tissues in the HdhQ150 Knock-In Mouse Model of Huntington's Disease

BACKGROUND:Huntington's disease (HD) is an inherited progressive neurodegenerative disorder caused by a CAG repeat expansion in the ubiquitously expressed HD gene resulting in an abnormally long polyglutamine repeat in the huntingtin protein. Polyglutamine inclusions are a hallmark of the neuropathology of HD. We have previously shown that inclusion pathology is also present in the peripheral tissues of the R6/2 mouse model of HD which expresses a small N-terminal fragment of mutant huntingtin. To determine whether this peripheral pathology is a consequence of the aberrant expression of this N-terminal fragment, we extend this analysis to the genetically precise knock-in mouse model of HD, HdhQ150, which expresses mutant mouse huntingtin. METHODOLOGY/PRINCIPAL FINDINGS:We have previously standardized the CAG repeat size and strain background of the R6/2 and HdhQ150 knock-in mouse models and found that they develop a comparable and widespread neuropathology. To determine whether HdhQ150 knock-in mice also develop peripheral inclusion pathology, homozygous Hdh(Q150/Q150) mice were perfusion fixed at 22 months of age, and tissues were processed for histology and immunohistochemistry with the anti-huntingtin antibody S830. The peripheral inclusion pathology was almost identical to that found in R6/2 mice at 12 weeks of age with minor differences in inclusion abundance. CONCLUSIONS/SIGNIFICANCE:The highly comparable peripheral inclusion pathology that is present in both the R6/2 and HdhQ150 knock-in models of HD indicates that the presence of peripheral inclusions in R6/2 mice is not a consequence of the aberrant expression of an N-terminal huntingtin protein. It remains to be determined whether peripheral inclusions are a pathological feature of the human disease. Both mouse models carry CAG repeats that cause childhood disease in humans, and therefore, inclusion pathology may be a feature of the childhood rather than the adult forms of HD. It is important to establish the extent to which peripheral pathology causes the peripheral symptoms of HD from the perspective of a mechanistic understanding and future treatment options

Age-Correlated Gene Expression in Normal and Neurodegenerative Human Brain Tissues

Human brain aging has received special attention in part because of the elevated risks of neurodegenerative disorders such as Alzheimer's disease in seniors. Recent technological advances enable us to investigate whether similar mechanisms underlie aging and neurodegeneration, by quantifying the similarities and differences in their genome-wide gene expression profiles.We have developed a computational method for assessing an individual's "physiological brain age" by comparing global mRNA expression datasets across a range of normal human brain samples. Application of this method to brains samples from select regions in two diseases--Alzheimer's disease (AD, superior frontal gyrus), frontotemporal lobar degeneration (FTLD, in rostral aspect of frontal cortex ∼BA10)--showed that while control cohorts exhibited no significant difference between physiological and chronological ages, FTLD and AD exhibited prematurely aged expression profiles.This study establishes a quantitative scale for measuring premature aging in neurodegenerative disease cohorts, and it identifies specific physiological mechanisms common to aging and some forms of neurodegeneration. In addition, accelerated expression profiles associated with AD and FTLD suggest some common mechanisms underlying the risk of developing these diseases

ソロモン島における昆虫成長制御剤ピリプロキシフェンの Anopheles farauti に対する野外効力評価

金沢大学留学生センター昆虫に対して高い幼若ホルモン様活性を示すピリプロキシフェン(S-31183)のAnopheles farautiに対する野外効力試験を, ソロモン諸島国, ガダルカナル島北部の淡水および半塩水の発生源で行った。その結果, ピリプロキシフェン乳剤の0.1ppm施用により, 淡水, 半塩水のいずれの発生源においても約2カ月以上にわたって70%以上の防除効果が得られた。ピリプロキシフェンの散布後に採集された幼虫および蛹が白色化しているのが観察され, 羽化阻害効果が持続する期間, この現象が続いた。 A field study to control the malarian vector, Anopheles farauti, with an insect growth regulator, pyriproxyfen (S-31183), was carried out in northern Guadalcanal in the Solomon Islands. An emulsifiable concentrate of 1% pyriproxyfen was applied to two breeding sites : one with fresh water and another with brackish water. Pyriproxyfen at a dosage of 0.1ppm inhibited emergence of An. farauti completely, at both test sites, for at least 5 weeks after treatment and the efficacy (more than 70% inhibition) lasted for ca. 2 months. The body color of the larvae and pupae in the test sites whitened noticeably after the application of the compound

Muscleblind1, but Not Dmpk or Six5, Contributes to a Complex Phenotype of Muscular and Motivational Deficits in Mouse Models of Myotonic Dystrophy

Assessment of molecular defects that underlie cognitive deficits observed in mendelian disorders provides a unique opportunity to identify key regulators of human cognition. Congenital Myotonic Dystrophy 1 (cDM1), a multi-system disorder is characterized by both cognitive deficits and a spectrum of behavioral abnormalities, which include visuo-spatial memory deficits, anxiety and apathy. Decreased levels of DMPK (Dystrophia Myotonica-protein kinase), SIX5, a transcription factor or MBNL1 (Muscleblind-like 1), an RNA splice regulator have been demonstrated to contribute to distinct features of cDM1. Mouse strains in which either Dmpk, Six5 or Mbnl1 are inactivated were therefore studied to determine the relative contribution of each gene to these cognitive functions. The open field and elevated plus maze tasks were used to examine anxiety, sucrose consumption was used to assess motivation, whereas the water maze and context fear conditioning were used to examine spatial learning and memory. Cognitive and behavioral abnormalities were observed only in Mbnl1 deficient mice, which demonstrate behavior consistent with motivational deficits in the Morris water maze, a complex visuo-spatial task and in the sucrose consumption test for anhedonia. All three models of cDM1 exhibit normal spatial learning and memory. These data identify MBNL1 as a potential regulator of emotional state with decreased MBNL1 levels underlying the motivational deficits observed in cDM1

琉球列島の西表島で蛙の鳴き声トラップに誘引された蚊類について

金沢大学留学生センター2004年6月12-18日に, 琉球列島の西表島の森林地帯の2ヵ所で, 蛙の声をCDプレイヤーで鳴らし, 直ぐ近くにCDCライトトラップを設置し蚊類を採集した.第一地点で合計777個体, 2地点で257個体のハエ目の昆虫が採集された.それらのうち, 次の4種の吸血性昆虫(雌)が両地点で目立って多く採集された.マックファレンチビカは第一地点で580個体(74.6%), 第二地点で193 (75.1), ヤエヤマカニアナチビカ19(2.4)と27 (10.5), ヤマトケヨソイカ106 (13.6)と20(7.8), また, ルソンコブハシカが第一地点のみで39個体(5.0%)が採集された.これらの蚊にケージ内でヌマガエルを暴露すると, 吸血行動が見られ, 多くの個体が吸血した.このことからこれらの蚊は自然界でカエルの鳴き声に誘引され, 吸血していると思われる. Mosquito collections were made at two foothill sites of Iriomote Island, the Ryukyu Archipelago, Japan, by modified CDC miniature light traps with a frog call CD player from June 12 to 18, 2004. A total of 777 and 257 female Diptera was collected at sites 1 and 2, respectively. Among them, 4 haematophagous species were predominant at sites 1 and 2-Uranotaenia macfarlanei with 580 (74.6%) and 193 (75.1%) individuals respectively, Ur. yaeyamana 19 (2.4%) and 27 (10.5%), and Corethrella nippon 106 (13.6%) and 20 (7.8%) which is a new record for Iriomote Island, and Mimomyia luzonensis with 39 (5.0%) individuals was predominant at site 1. The females of these species collected by the traps fed easily on a frog, Rana limnocharis exposed in the cage. The results demonstrated clearly that frog call is the primary stimulus in guiding these Culicine and Chaoborine flies in their search for host animals in nature

Real Time Imaging of Human Progenitor Neurogenesis

Human neural progenitors are increasingly being employed in drug screens and emerging cell therapies targeted towards neurological disorders where neurogenesis is thought to play a key role including developmental disorders, Alzheimer’s disease, and depression. Key to the success of these applications is understanding the mechanisms by which neurons arise. Our understanding of development can provide some guidance but since little is known about the specifics of human neural development and the requirement that cultures be expanded in vitro prior to use, it is unclear whether neural progenitors obey the same developmental mechanisms that exist in vivo. In previous studies we have shown that progenitors derived from fetal cortex can be cultured for many weeks in vitro as undifferentiated neurospheres and then induced to undergo neurogenesis by removing mitogens and exposing them to supportive substrates. Here we use live time lapse imaging and immunocytochemical analysis to show that neural progenitors use developmental mechanisms to generate neurons. Cells with morphologies and marker profiles consistent with radial glia and recently described outer radial glia divide asymmetrically and symmetrically to generate multipolar intermediate progenitors, a portion of which express ASCL1. These multipolar intermediate progenitors subsequently divide symmetrically to produce CTIP2+ neurons. This 3-cell neurogenic scheme echoes observations in rodents in vivo and in human fetal slice cultures in vitro, providing evidence that hNPCs represent a renewable and robust in vitro assay system to explore mechanisms of human neurogenesis without the continual need for fresh primary human fetal tissue. Knowledge provided by this and future explorations of human neural progenitor neurogenesis will help maximize the safety and efficacy of new stem cell therapies by providing an understanding of how to generate physiologically-relevant cell types that maintain their identities when placed in diagnostic or transplantation environments