ApoE and TDP-43 neuropathology in two siblings with familial FTLD-motor neuron disease

Frontotemporal lobar degeneration with motor neuron disease (FTLD-MND) is characterized by neuronal cytoplasmic inclusions containing TDP-43. Apolipoprotein E4 (apoE4), derived from the apoE ?4 allele, enhances brain atrophy in FTLD through unknown mechanisms. Here, we studied two siblings with C9ORF72-linked familial FTLD-MND, an apoE ?4 homozygote and an apoE ?3 homozygote. The apoE ?4 homozygote had more cognitive-behavioral symptoms, fronto-insulo-temporal atrophy, and apoE fragments and aggregates in the anterior cingulate cortex. ApoE formed complexes with TDP-43 that were more abundant in the apoE ?4 homozygote. Although differences seen in a sibling pair could arise due to chance, these findings raise the possibility that apoE4 exacerbates brain pathology in FTLD through formation of neurotoxic apoE fragments and interactions with TDP-43.     

The mechanism of astragaloside IV promoting sciatic nerve regeneration

3-O-beta-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-cycloastragenol (astragaloside Ⅳ), the main active component of the traditional Chinese medicine astragalus membranaceus, has been shown to be neuroprotective. This study investigated whether astragaloside Ⅳ could promote the repair of injured sciatic nerve. Denervated sciatic nerve of mice was subjected to anastomosis. The mice were intraperitoneally injected with 10, 5, 2.5 mg/kg astragaloside Ⅳ per day for 8 consecutive days. Western blot assay and real-time PCR results demonstrated that growth-associated protein-43 expression was upregulated in mouse spinal cord segments L4-6 after intervention with 10, 5, 2.5 mg/kg astragaloside Ⅳ per day in a dose-dependent manner. Luxol fast blue staining and electrophysiological detection suggested that astragaloside Ⅳ elevated the number and diameter of myelinated nerve fibers, and simultaneously increased motor nerve conduction velocity and action potential amplitude in the sciatic nerve of mice. These results indicated that astragaloside Ⅳ contributed to sciatic nerve regeneration and functional recovery in mice. The mechanism underlying this effect may be associated with the upregulation of growth-associated protein-43 expression.     

Nuclear TAR DNA-binding protein 43 A new target for amyotrophic lateral sclerosis treatment

Abnormal TAR DNA-binding protein 43 （TDP-43） inclusion bodies can be detected in the degen- erative neurons of amyotrophic lateral sclerosis. In this study, we induced chronic oxidative stress injury by applying malonate to cultured mouse cortical motor neurons. In the later stages of the malonate insult, TDP-43 expression reduced in the nuclei and transferred to the cytoplasm. This was accompanied by neuronal death, mimicking the pathological changes in TDP-43 that are seen in patients with amyotrophic lateral sclerosis. Interestingly, in the early stages of the response to malonate treatment, nuclear TDP-43 expression increased, and neurons remained relatively intact, without inclusion bodies or fragmentation. Therefore, we hypothesized that the increase of nuclear TDP-43 expression might be a pro-survival factor against oxidative stress injury. This hypothesis was confirmed by an in vitro transgenic experiment, in which overexpression of wild type mouse TDP-43 in cultured cortical motor neurons significantly reduced malonate-induced neuronal death. Our findings suggest that the loss of function of TDP-43 is an important cause of neuronal degen- eration, and upregulation of nuclear TDP-43 expression might be neuroprotective in amyotrophic lateral sclerosis.     

Maturational changes in connexin 43 expression in the seminiferous tubules may depend on thyroid hormone action

Introduction

Connexin 43 (Cx43) mediates the effect of thyroid hormone on Sertoli cell maturation in vitro. We investigated the influence of triiodothyronine (T3) administration on Cx43 expression in relation to the progress in seminiferous tubule maturation.

Material and methods

Male rats were daily injected with 100 µg T3/kg body weight from birth until postnatal day (pnd) 5 (transient treatment – tT3) or until pnd 15 (continuous treatment – cT3) or solvent – control (C). On pnd 16 serum hormone levels, body and testes weight, seminiferous tubule morphometry, Cx43 immunostaining and germ cell degeneration were investigated. Cx43 expression was also assessed in six 50-day-old adult untreated rats.

Result

tT3 increased 2.6-fold serum level of T3, testes weight, and seminiferous tubule diameter, and induced maturation-like dislocation of Cx43 expression from the apical to the peripheral region of Sertoli cell cytoplasm. In addition, incidence of Cx43-positive tubules declined from 86% in C to 46% after tT3, being similar to the adult value (30% of tubules Cx43-positive). In turn, cT3 increased serum T3 level 12-fold, and decreased body weight. Seminiferous tubules became shortened and distended, Sertoli cell cytoplasm vacuolated, Cx43 expression had minimal intensity and germ cell degeneration increased.

Conclusions

Cx43 might intermediate a short and transient stimulatory effect of T3 on seminiferous tubule maturation that disappeared together with exposure to the toxic effect of a continuously high level of the hormone.     

Ghrelin对大鼠心肌梗死后电重构的影响

目的 观察Ghrelin对大鼠心肌梗死后电重构的作用.方法 将65只SD大鼠随机分成假手术组(n=15)和心肌梗死组(n=50).假手术组开胸后剪开心包腔,不结扎冠状动脉.心肌梗死组大鼠结扎冠状动脉前降支制作心肌梗死模型.存活7d的大鼠随机分成Ghrelin干预组(n=17)和梗死对照组(n=17).Ghrelin干预组按Ghrelin 100 μg/kg的剂量皮下注射,2次/d.梗死对照组和假手术组皮下注射等量生理盐水.28 d后采用程控刺激进行在体电生理测定,采用免疫组化方法检测缝隙连接蛋白43(Cx43)的分布,免疫印迹法检测Cx43蛋白表达,实时定量PCR法检测Cx43 mRNA表达.结果 与梗死对照组相比,Ghrelin能显著降低室性心动过速(室速)的诱发率(P＜0.05),心律失常评分也显著降低(P＜0.05).与假手术组相比,梗死心肌内Cx43表达显著降低(P＜0.05),Ghrelin干预使梗死周边心肌Cx43及其mRNA水平增加(P＜0.05).结论 Ghrelin能改善心肌梗死后大鼠心脏的电生理学特性,增加心肌Cx43的表达,防止室性心律失常的发生,可能对心血管系统具有保护作用.     

失血性休克大鼠复苏前后胃Cajal 间质细胞及Cx43的变化

目的：探讨失血性休克复苏前后大鼠胃Cajal间质细胞及间隙连接蛋白Connexin 43（Cx43）的变化。方法：SD大鼠随机均分为对照组与实验组。对照组大鼠行假手术;实验组大鼠通过放血制作失血性休克模型,维持休克状态1 h后行液体复苏。分别于休克1 h和复苏治疗后3,6,12,24 h取大鼠胃组织于电镜下观察Cajal细胞超微结构;免疫荧光染色及Western blot检测Cx43的表达。结果：电镜显示实验组休克1 h时Cajal细胞水肿、核皱缩、基膜破坏;复苏治疗后3,6 h无明显变化,12 h时结构开始逐渐恢复,至24 h Cajal细胞恢至接近对照组状态。免疫荧光染色发现实验组Cx43荧光强度于休克1 h明显减弱,但从复苏治疗后逐渐升高,至24 h基本接近对照组。Western blot法显示Cx43蛋白表达量变化与免疫荧光染色结果相一致。结论：失血性休克能导致Cajal细胞损伤与Cx43表达减少,两者改变所造成细胞间信息传递缺陷可能是失血性休克时胃肠道动力障碍的重要原因之一。     

RNA quality control and protein aggregates in amyotrophic lateral sclerosis: A review

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease in adults. The biologic basis of ALS remains unknown. However, ALS research has taken a dramatic turn over the past 4 years. Ground breaking discoveries of mutations of genes that encode RNA processing proteins, and demonstration that abnormal aggregates of these and other proteins precede motor neuron loss in familial and sporadic ALS, have initiated a paradigm shift in understanding the pathogenic mechanisms of ALS. Curiously, some of these RNA binding proteins have prion‐like domains, with a propensity to self‐aggregation. The emerging hypothesis that a focal cascade of toxic protein aggregates, and their consequent non–cell‐autonomous spread to neighborhood groups of neurons, fits the classical temporo‐spatial progression of ALS. This article reviews the current research efforts toward understanding the role of RNA‐processing regulation and protein aggregates in ALS. Muscle Nerve 47:330‐338, 2013     

Exposure to female estrous is beneficial for male mice against transient ischemic stroke

ABSTRACT

Objective: Exposure to female estrous, a natural rewarding experience, alleviates anxiety and depression, and the contribution of this behavior to stroke outcome is unknown. The aim of this study was to evaluate whether exposure to female estrous is beneficial to recovery following transient ischemic stroke in male mice.

Methods: Cerebral ischemia was induced in male ICR mice with thread occlusion of the middle cerebral artery (MCAO) for 30 min followed by reperfusion. MCAO mice were randomly divided into MCAO group and Estrous Female Exposure (EFE) group. The mice in the EFE group were subjected to estrous female mouse interaction from day 1 until the end of the experiment. Mortality was recorded during the investigation. Behavioral functions were assessed by a beam-walking test and corner test from day 1 to day 10 after MCAO. Serum testosterone levels were analyzed with ELISA, and the expression levels of growth-associated protein-43 (GAP-43) and synaptophysin in the cortex of the ischemic hemisphere were determined by western blot on day 7 after MCAO.

Results: Exposure to female estrous reduced the mortality induced by cerebral ischemic lesions. The beam-walking test demonstrated that exposure to female estrous significantly improved motor function recovery. The serum testosterone levels and ischemic cortex GAP-43 expression were significantly higher in MCAO male mice exposed to female estrous.

Conclusion: Exposure to female estrous reduces mortality and improves functional recovery in MCAO male mice. The study provides the first evidence to support the importance of female interaction to male stroke rehabilitation.

Abbreviations: GAP-43: growth-associated protein-43; SYP: Synaptophysin; MCAO: middle cerebral artery occlusion; OVXs: ovariectomies; CCA: common carotid artery; ECA: external carotid artery; EFE: estrous female exposure; TTC: 2,3,5-triphenyltetrazolium chloride; PAGE: polyacrylamide gel electrophoresis; PVDF: polyvinylidene difluoride; ANOVA: analysis of variance; LSD: least significant difference     

Aberrant trafficking of a Leu89Pro connexin32 mutant associated with X-linked dominant Charcot–Marie–Tooth disease

Objective: To determine the functional abnormalities of the Leu89Pro mutation in connexin32 (CX32), which we have previously reported is present within an X-linked dominant Charcot–Marie–Tooth disease family. In this family, male patients were moderately to severely affected.

Methods: We performed immunofluorescence to investigate whether the Leu89Pro CX32 protein was transported to the cell membrane in HeLa and Schwann cells. First, we constructed the eukaryotic express plasmids expressing CX32 (wild-type or Leu89Pro) and enhanced green fluorescent protein by the gene recombination technology. Then the recombinant plasmids were transiently transfected into communication-incompetent HeLa cells and human Schwann cells by the lipofectamine method. Later, we double-labeled cells for both CX32 and markers of the ER (calnexin) or the Golgi (58-kDa protein) at 24 h or 48 h. The images were collected using a Leica TCS SP5 II confocal microscope.

Results: The mutant CX32 protein was localized in the endoplasmic reticulum and failed to reach the cell membrane to form gap junctions.

Conclusion: Our results indicated that the Leu89Pro substitution in the second transmembrane domain of CX32 disrupts the trafficking of the protein, inhibiting the assembly of CX32 gap junctions, which in turn may result in peripheral neuropathy. This functional abnormality may explain the moderate to severe phenotype seen in Leu89Pro patients, and as such represents a promising therapeutic target in the treatment of this subset of CMTX patients.     

Neuropathology of the hippocampus in FTLD‐Tau with Pick bodies: a study of the BrainNet Europe Consortium

G. G. Kovacs, A. J. M. Rozemuller, J. C. van Swieten, E. Gelpi, K. Majtenyi, S. Al‐Sarraj, C. Troakes, I. Bódi, A. King, T. Hortobágyi, M. M. Esiri, O. Ansorge, G. Giaccone, I. Ferrer, T. Arzberger, N. Bogdanovic, T. Nilsson, I. Leisser, I. Alafuzoff, J. W. Ironside, H. Kretzschmar and H. Budka (2013) Neuropathology and Applied Neurobiology 39, 166–178 Neuropathology of the hippocampus in FTLD‐Tau with Pick bodies: a study of the BrainNet Europe Consortium Aims: Frontotemporal lobar degeneration with Pick bodies (Pick's disease) is characterized by the presence of tau immunoreactive spherical structures in the cytoplasm of neurones. In view of confusion about the molecular pathology of Pick's disease, we aimed to evaluate the spectrum of tau pathology and concomitant neurodegeneration‐associated protein depositions in the characteristically affected hippocampus. Methods: We evaluated immunoreactivity (IR) for tau (AT8, 3R, 4R), α‐synuclein, TDP43, p62, and ubiquitin in the hippocampus, entorhinal and temporal cortex in 66 archival cases diagnosed neuropathologically as Pick's disease. Results: Mean age at death was 68.2 years (range 49–96). Fifty‐two (79%) brains showed 3R immunoreactive spherical inclusions in the granule cells of the dentate gyrus. These typical cases presented mainly with the behavioural variant of frontotemporal dementia, followed by progressive aphasia, mixed syndromes or early memory disturbance. α‐Synuclein IR was seen only in occasional spherical tau‐positive inclusions, TDP‐43 IR was absent, and 4R IR was present only as neurofibrillary tangles in pyramidal neurones. Aβ IR was observed in 16 cases; however, the overall level of Alzheimer's disease‐related alterations was mainly low or intermediate (n = 3). Furthermore, we identified six cases with unclassifiable tauopathy. Conclusions: (i) Pick's disease may occur also in elderly patients and is characterized by a relatively uniform pathology with 3R tau inclusions particularly in the granule cells of dentate gyrus; (ii) even minor deviation from these morphological criteria suggests a different disorder; and (iii) immunohistological revision of archival cases expands the spectrum of tauopathies that require further classification.