Towards understandings of serine/arginine-rich splicing factors

Serine/arginine-rich splicing factors (SRSFs) refer to twelve RNA-binding proteins which regulate splice site recognition and spliceosome assembly during precursor messenger RNA splicing. SRSFs also participate in other RNA metabolic events, such as transcription, translation and nonsense-mediated decay, during their shuttling between nucleus and cytoplasm, making them indispensable for genome diversity and cellular activity. Of note, aberrant SRSF expression and/or mutations elicit fallacies in gene splicing, leading to the generation of pathogenic gene and protein isoforms, which highlights the therapeutic potential of targeting SRSF to treat diseases. In this review, we updated current understanding of SRSF structures and functions in RNA metabolism. Next, we analyzed SRSF-induced aberrant gene expression and their pathogenic outcomes in cancers and non-tumor diseases. The development of some well-characterized SRSF inhibitors was discussed in detail. We hope this review will contribute to future studies of SRSF functions and drug development targeting SRSFs.

Phosphorylated TDP-43 Staging of Primary Age-Related Tauopathy / 神经科学通报·英文版

Primary age-related tauopathy (PART) is characterized by tau neurofibrillary tangles (NFTs) in the absence of amyloid plaque pathology. In the present study, we analyzed the distribution patterns of phosphorylated 43-kDa TAR DNA-binding protein (pTDP-43) in the brains of patients with PART. Immunohistochemistry and immunofluorescence double-labeling in multiple brain regions was performed on brain tissues from PART, Alzheimer's disease (AD), and aging control cases. We examined the regional distribution patterns of pTDP-43 intraneuronal inclusions in PART with Braak NFT stages > 0 and ≤ IV, and a Thal phase of 0 (no beta-amyloid present). We found four stages which indicated potentially sequential dissemination of pTDP-43 in PART. Stage I was characterized by the presence of pTDP-43 lesions in the amygdala, stage II by such lesions in the hippocampus, stage III by spread of pTDP-43 to the neocortex, and stage IV by pTDP-43 lesions in the putamen, pallidum, and insular cortex. In general, the distribution pattern of pTDP-43 pathology in PART cases was similar to the early TDP-43 stages reported in AD, but tended to be more restricted to the limbic system. However, there were some differences in the distribution patterns of pTDP-43 between PART and AD, especially in the dentate gyrus of the hippocampus. Positive correlations were found in PART between the Braak NFT stage and the pTDP-43 stage and density.

Pay attention to primary age-related tauopathy / 中华神经科杂志

Primary age-related tauopathy (PART) is a type of pathological change characterized by the deposition of tau protein in the brain confined to the entorhinal cortex and hippocampus (Braak stage 0-Ⅳ), with no or little amyloid-β protein (Aβ) deposition (Thal Aβ stage 0-2). In recent years, PART has received lots of attention, but its relationship with Alzheimer's disease (AD) remains controversial. Therefore, strengthening the understanding of PART among clinicians and relevant researchers is of great value in interpretation of the relationship between brain aging and AD as well as other cognitive impairment diseases.

Pay attention to primary age?related tauopathy / 中华神经科杂志

Primary age?related tauopathy (PART) is a type of pathological change characterized by the deposition of tau protein in the brain confined to the entorhinal cortex and hippocampus (Braak stage 0-Ⅳ), with no or little amyloid?β protein (Aβ) deposition (Thal Aβ stage 0-2). In recent years, PART has received lots of attention, but its relationship with Alzheimer′s disease (AD) remains controversial. Therefore, strengthening the understanding of PART among clinicians and relevant researchers is of great value in interpretation of the relationship between brain aging and AD as well as other cognitive impairment diseases.

No Evidence of a Contribution of the Vestibular System to Frequent Falls in Progressive Supranuclear Palsy

BACKGROUND AND PURPOSE: Conflicting results about vestibular function in progressive supranuclear palsy (PSP) prompted a systematic examination of the semicircular canal function, otolith function, and postural stability. METHODS: Sixteen patients with probable PSP [9 females, age=72±6 years (mean±SD), mean disease duration=3.6 years, and mean PSP Rating Scale score=31] and 17 age-matched controls were examined using the video head impulse test, caloric testing, ocular and cervical vestibular evoked myogenic potentials (o- and cVEMPs), video-oculography, and posturography. RESULTS: There was no evidence of impaired function of the angular vestibulo-ocular reflex (gain=1.0±0.1), and caloric testing also produced normal findings. In terms of otolith function, there was no significant difference between PSP patients and controls in the absolute peakto-peak amplitude of the oVEMP (13.5±7.2 µV and 12.5±5.6 µV, respectively; p=0.8) or the corrected peak-to-peak amplitude of the cVEMP (0.6±0.3 µV and 0.5±0.2 µV, p=0.3). The total root-mean-square body sway was significantly increased in patients with PSP compared to controls (eyes open/head straight/hard platform: 9.3±3.7 m/min and 6.9±2.1 m/min, respectively; p=0.032). As expected, the saccade velocities were significantly lower in PSP patients than in controls: horizontal, 234±92°/sec and 442±66°/sec, respectively; downward, 109±105°/sec and 344±72°/sec; and upward, 121±110°/sec and 348±78°/sec (all p<0.01). CONCLUSIONS: We found no evidence of impairment of either high- or low-frequency semicircular function or otolith organ function in the examined PSP patients. It therefore appears that other causes such as degeneration of supratentorial pathways lead to postural imbalance and falls in patients with PSP.

Gait Ignition Failure in JNPL3 Human Tau-mutant Mice

Cognitive impairments and motor dysfunction are commonly observed behavioral phenotypes in genetic animal models of neurodegenerative diseases. JNPL3 transgenic mice expressing human P301L-mutant tau display motor disturbances with age- and gene dose-dependent development of neurofibrillary tangles, suggesting that tau pathology causes neurodegeneration associated with motor behavioral abnormalities. Although gait ignition failure (GIF), a syndrome marked by difficulty in initiating locomotion, has been described in patients with certain forms of tauopathies, transgenic mouse models mirroring human GIF syndrome have yet to be reported. Using the open field and balance beam tests, here we discovered that JNPL3 homozygous mice exhibit a marked delay of movement initiation. The elevated plus maze excluded the possibility that hesitation to start in JNPL3 mice was caused by enhanced levels of anxiety. Considering the normal gait ignition in rTg4510 mice expressing the same mutant tau in the forebrain, GIF in JNPL3 mice seems to arise from abnormal tau deposition in the hindbrain areas involved in locomotor initiation. Accordingly, immunohistochemistry revealed highly phosphorylated paired helical filament tau in JNPL3 brainstem areas associated with gait initiation. Together, these findings demonstrate a novel behavioral phenotype of impaired gait initiation in JNPL3 mice and underscore the value of this mouse line as a tool to study the neural mechanisms and potential treatments for human GIF syndrome.

Targeted Downregulation of kdm4a Ameliorates Tau-engendered Defects in Drosophila melanogaster

BACKGROUND: Tauopathies, a class of neurodegenerative diseases that includes Alzheimer's disease (AD), are characterized by the deposition of neurofibrillary tangles composed of hyperphosphorylated tau protein in the human brain. As abnormal alterations in histone acetylation and methylation show a cause and effect relationship with AD, we investigated the role of several Jumonji domain-containing histone demethylase (JHDM) genes, which have yet to be studied in AD pathology. METHODS: To examine alterations of several JHDM genes in AD pathology, we performed bioinformatics analyses of JHDM gene expression profiles in brain tissue samples from deceased AD patients. Furthermore, to investigate the possible relationship between alterations in JHDM gene expression profiles and AD pathology in vivo, we examined whether tissue-specific downregulation of JHDM Drosophila homologs (kdm) can affect tauR406W-induced neurotoxicity using transgenic flies containing the UAS-Gal4 binary system. RESULTS: The expression levels of JHDM1A, JHDM2A/2B, and JHDM3A/3B were significantly higher in postmortem brain tissue from patients with AD than from non-demented controls, whereas JHDM1B mRNA levels were downregulated in the brains of patients with AD. Using transgenic flies, we revealed that knockdown of kdm2 (homolog to human JHDM1), kdm3 (homolog to human JHDM2), kdm4a (homolog to human JHDM3A), or kdm4b (homolog to human JHDM3B) genes in the eye ameliorated the tauR406W-engendered defects, resulting in less severe phenotypes. However, kdm4a knockdown in the central nervous system uniquely ameliorated tauR406W-induced locomotion defects by restoring heterochromatin. CONCLUSION: Our results suggest that downregulation of kdm4a expression may be a potential therapeutic target in AD.

Development of tau PET Imaging Ligands and their Utility in Preclinical and Clinical Studies / 대한핵의학회잡지

The pathological features of Alzheimer's disease are senile plaques which are aggregates of β-amyloid peptides and neurofibrillary tangles in the brain. Neurofibrillary tangles are aggregates of hyperphosphorylated tau proteins, and these induce various other neurodegenerative diseases, such as progressive supranuclear palsy, corticobasal degeneration, frontotemporal lobar degeneration, frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), and chronic traumatic encephalopathy. In the case of Alzheimer's disease, the measurement of neurofibrillary tangles associated with cognitive decline is suitable for differential diagnosis, disease progression assessment, and to monitor the effects of therapeutic treatment. This review discusses considerations for the development of tau ligands for imaging and summarizes the results of the first-in-human and preclinical studies of the tau tracers that have been developed thus far. The development of tau ligands for imaging studies will be helpful for differential diagnosis and for the development of therapeutic treatments for tauopathies including Alzheimer's disease.

Encephalopathy associated with anti-IgLON5 antibody: report of three cases / 中华神经科杂志

Objective To report the clinical and paraclinical features of a case series with antiIgLON5 antibody related encephalopathy.Methods One hundred and fifty patients with sleep disorders and subacute or chronic onset of movement disorders,parkinsonism or bulbar palsy were included.The serum and cerebrospinal fluid specimens of these patients were screened for anti-IgLON5 antibody.The clinical and paraclinical features of patients with seropositive anti-IgLON5 antibody were summarized.Results Three patients with seropositive anti-IgLON5 antibody were identified,with one female and two males.The onset age ranged from 61 to 64 years.Case 1 presented with symptoms of involuntary movement,unsteady walk and insomnia;case 2 with symptoms of insomnia,sleep behavioral disorder,psychiatric behavior and dysphagia;case 3 with symptoms of insomnia,sleep behavioral disorder,dysarthria,and tremor.When examined by polysomnography,obstructive sleep apnea syndrome was revealed in cases 1 and 2,serious insomnia was found in cases 2 and 3,and sleep behavioral disorder was revealed in case 2.All three patients were positive for HLA-DQB1 * 0501,and cases 2 and 3 were positive for HLA-DRB1 * 1001.All three patients received immunotherapy and only one patient (case 1) responded well to immunotherapy with intravenous immunoglobulin,steroids and mycophenolate mofetil.Conclusions Anti-IgLON5-related encephalopathy is a rare disease with distinct clinical features of both autoimmune disorders and neurodegeneration disorders.These patients may benefit from immunotherapy.

Aberrant Activation of Cdc2/cyclin B1 Is Involved in Initiation of Cytoskeletal Pathology in Murine Niemann-Pick Disease Type C / 华中科技大学学报（医学）（英德文版）

Niemann-Pick disease type C (NPC) is a fatal,neurovisceral lipid storage disease,neuropathologically characterized by cytoplasmic sequestration of glycolipids in neurons,progressive neuronal loss,neurofibrillary tangles (NFTs) formation,and axonal spheroids (AS).Cytoskeletal pathology including accumulation of hyperphosphorylated cytoskeletal proteins is a neuropathological hallmark of the mouse model of NPC (npc mice).With a goal of elucidating the mechanisms underlying the lesion formation,we investigated the temporal and spatial characteristics of cytoskeletal lesions and the roles of cdc2,cdk4,and cdk5 in lesion formation in young npc mice.Cytoskeletal lesions were detectable in npc mice at three weeks of age.Importantly,concomitant activation of cdc2/cyclin B 1 kinase and accumulation of a subsequently generated cohort of phospho-epitopes were detected.The activation of cdk4/cyclin D1 and cdk5/p25 kinases was observed during the fourth week of life in npc mice,and this activation contributed to the lesion formation.We concluded that the progression of cytoskeletal pathology in npc mice older than four weeks is accelerated by the cumulative effect of cdc2,cdk4,and cdk5 activation.Furthermore,cdc2/cyclin B1 may act as a key initial player one week earlier.Targeting cell cycle activation may be beneficial to slow down the NPC pathogenesis.

Clinical Approach to Progressive Supranuclear Palsy

Sixty years ago, Steele, Richardson and Olszewski designated progressive supranuclear palsy (PSP) as a new clinicopathological entity in their seminal paper. Since then, in addition to the classic Richardson's syndrome (RS), different clinical phenotypic presentations have been linked with this four-repeat tauopathy. The clinical heterogeneity is associated with variability of regional distribution and severity of abnormal tau accumulation and neuronal loss. In PSP subtypes, the presence of certain clinical pointers may be useful for antemortem prediction of the underlying PSP-tau pathology. Midbrain atrophy on conventional MRI correlates with the clinical phenotype of RS but is not predictive of PSP pathology. Cerebrospinal fluid biomarkers and tau ligand positron emission tomography are promising biomarkers of PSP. A multidisciplinary approach to meet the patients' complex needs is the current core treatment strategy for this devastating disorder.

Progressive supranuclear palsy: new concepts / Paralisia supranuclear progressiva: conceitos atuais

Progressive supranuclear palsy (PSP) is a distinctive form of neurodegenerative disease which affects the brainstem and basal ganglia. Patients present supranuclear ophthalmoplegia, postural instability and mild dementia. PSP is defined neuropathologically by the accumulation of neurofibrillary tangles in the subthalamic nucleus, pallidum, red nucleus, substantia nigra, striatum, pontine tegmentum, oculomotor nucleus, medulla and dentate nucleus. Over the last decade many lines of investigations have helped refine PSP in many aspects and it is the purpose of this review to help neurologists identify PSP, to better understand its pathophysiology and to provide a more focused, symptom-based treatment approach.

A paralisia supranuclear progressiva (PSP) é uma doença neurodegenerativa, que afeta principalmente o tronco cerebral e os núcleos da base. O quadro clínico se caracteriza por oftalmoparesia supranuclear, instabilidade postural e demência . Do ponto de vista anátomo-patológico, a PSP se caracteriza por acúmulo de emaranhados neurofibrilares no núcleo subtalâmico, globo pálido, núcleo rubro, substância negra, estriado, tegumento da ponte, núcleos oculomotores, bulbo e núcleo denteado. Nas últimas décadas, muitas linhas de pesquisa têm colaborado para redefinir a PSP em muitos aspectos. Os objetivos dessa revisão são auxiliar o neurologista geral na identificação da doença, compreensão da sua fisiopatologia, além de apresentar alternativas para seu tratamento sintomático.