Xinzhen Yin

Intranasal insulin alleviates cognitive deficits and amyloid pathology in young adult APPswe/PS1dE9 mice.

Brain insulin signaling deficits contribute to multiple pathological features of Alzheimers disease (AD). Although intranasal insulin has shown efficacy in patients with AD, the underlying mechanisms remain largely unillustrated. Here, we demonstrate that intranasal insulin improves cognitive deficits, ameliorates defective brain insulin signaling, and strongly reduces β‐amyloid (Aβ) production and plaque formation after 6 weeks of treatment in 4.5‐month‐old APPswe/PS1dE9 (APP/PS1) mice. Furthermore, c‐Jun N‐terminal kinase activation, which plays a pivotal role in insulin resistance and AD pathologies, is significantly inhibited. The alleviation of amyloid pathology by intranasal insulin results mainly from enhanced nonamyloidogenic processing and compromised amyloidogenic processing of amyloid precursor protein (APP), and from a reduction in apolipoprotein E protein which is involved in Aβ metabolism. In addition, intranasal insulin effectively promotes hippocampal neurogenesis in APP/PS1 mice. This study, exploring the mechanisms underlying the beneficial effects of intranasal insulin on Aβ pathologies in vivo for the first time, highlights important preclinical evidence that intranasal insulin is potentially an effective therapeutic method for the prevention and treatment of AD.

(CAG)n loci as genetic modifiers of age-at-onset in patients with Machado-Joseph disease from mainland China

Sir, We read with great interest the article published in Brain by Tezenas du Montcel et al. (2014) reporting modifying factors of age-at-onset in 1255 individuals affected with spinocerebellar ataxia (SCA) types 1, 2, 3, 6 and 7, recruited through the European Consortium on Spinocerebellar Ataxias (EUROSCA). We would like to report our findings on genetic modifiers and age-at-onset in 802 Chinese Han patients (429 males, 373 females) with Machado-Joseph disease (MJD/SCA3), on behalf of the Chinese Clinical Research Cooperative Group for Spinocerebellar Ataxias (CCRCG-SCA). Our study was approved by the ethics committee of Xiangya Hospital, Central South University. Blood samples were collected after written informed consent from all subjects. All MJD patients were genotyped for ATXN3 and nine other polyQ-related genes ( ATXN1 , ATXN2 , CACNA1A , ATXN7 , TBP , ATN1 , KCNN3 , RAI1 and HTT ). None of the MJD patients was a ‘homozygote’ (i.e. bearing two expanded alleles). We used a similar statistical strategy as described by the EUROSCA consortium (Tezenas du Montcel et al. , 2014). For some polyQ-related genes ( ATXN1 , TBP , ATN1 and HTT ), the sizes of the shorter and the longer alleles were considered (separately) as continuous variables; given the skewed distribution of allele size in the other genes ( ATXN2 , ATXN3 , ATXN7 , CACNA1A and RAI1 ) these were classified as short, short-medium, medium or long (Table 1). The interaction between both alleles, their mean length and the size difference between alleles at each locus were also considered as dependent variables. View this table: Table 1 Classification of polyQ-related normal alleles according to the number of CAG repeats The logarithmically transformed age-at-onset was treated as a dependent variable with homoscedasticity. Linear regression analysis (linear and quadratic effects) was performed to estimate the effect on age-at-onset of the expanded allele at ATXN3. Different models were then …

Long-term treatment with intranasal insulin ameliorates cognitive impairment, tau hyperphosphorylation, and microglial activation in a streptozotocin-induced Alzheimer’s rat model

Recent evidence reveals that aberrant brain insulin signaling plays an important role in the pathology of Alzheimer’s disease (AD). Intranasal insulin administration has been reported to improve memory and attention in healthy participants and in AD patients. However, the underlying molecular mechanisms are poorly understood. Here, we treated intracerebroventricular streptozotocin-injected (ICV-STZ) rats, a commonly used animal model of sporadic AD, with daily intranasal delivery of insulin (2 U/day) for 6 consecutive weeks and then studied their cognitive function with the Morris water maze test and biochemical changes via Western blotting. We observed cognitive deficits, tau hyperphosphorylation, and neuroinflammation in the brains of ICV-STZ rats. Intranasal insulin treatment for 6 weeks significantly improved cognitive function, attenuated the level of tau hyperphosphorylation, ameliorated microglial activation, and enhanced neurogenesis in ICV-STZ rats. Additionally, our results indicate that intranasal delivery of insulin probably attenuates tau hyperphosphorylation through the down-regulation of ERK1/2 and CaMKII in the brains of ICV-STZ rats. Our findings demonstrate a beneficial effect of intranasal insulin and provide the mechanistic basis for treating AD patients with intranasal insulin.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: Phenotypic and mutational spectrum in patients from mainland China

Aims: To analyze the NOTCH3 gene mutations in patients from mainland China clinically suspected to have cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and evaluate large intracranial arteries in CADASIL patients. Methods: We performed clinical, neuroimaging and NOTCH3 gene (exons 2–23) examinations in 47 subjects from 34 families. Large intracranial arteries were assessed using magnetic resonance angiography (MRA) in 19 cases with NOTCH3 gene variants. Results: Screening of exons 3 and 4 identified six different known mutations in eight families and two novel mutations in two families. Further screening of the remaining exons identified p.R1175W, a variant of unknown significance. The incidence of NOTCH3 mutations was 29.4% (10/34). Five cases with NOTCH3 mutations showed intracranial atherosclerosis. One patient developed cerebral infarction due to left middle cerebral artery occlusion (M2 segment). Conclusions: The NOTCH3 mutation spectrum in our group was diverse and consistent with those in Caucasians but differed from those in Korea and Taiwan. The screening strategy used in Caucasian populations can be applied to mainland Chinese patients. Atherosclerosis of the large intracranial arteries involvement does not exclude CADASIL diagnosis.

FERM Domain Containing Protein 7 Interacts with the Rho GDP Dissociation Inhibitor and Specifically Activates Rac1 Signaling

The FERM domain containing protein 7 gene (FRMD7) associated with the X-linked disorder idiopathic congenital nystagmus (ICN) is involved in the regulation of neurite elongation during neuronal development. Members of the Rho family of small G-proteins (Rho GTPases) are key regulators of the actin cytoskeleton and are implicated in the control of neuronal morphology. The Rho GDP dissociation inhibitor alpha, RhoGDIα, the main regulator of Rho GTPases, can form a complex with the GDP-bound form of Rho GTPases and inhibit their activation. Here, we demonstrate that the full length of the mouse FRMD7, rather than the N-terminus or the C-terminus alone, directly interacts with RhoGDIα and specifically initiates Rac1 signaling in mouse neuroblastoma cell line (neuro-2a). Moreover, we show that wild-type human FRMD7 protein is able to activate Rac1 signaling by interacting with RhoGDIα and releasing Rac1 from Rac1-RhoGDIα complex. However, two missense mutations (c.781C>G and c.886G>C) of human FRMD7 proteins weaken the ability to interact with RhoGDIα and release less Rac1, that induce the activation of Rac1 to a lesser degree; while an additional mutant, c.1003C>T, which results in a C-terminal truncated protein, almost fails to interact with RhoGDIα and to activate Rac1 signaling. Collectively, these results suggest that FRMD7 interacts with one of the Rho GTPase regulators, RhoGDIα, and activates the Rho subfamily member Rac1, which regulates reorganization of actin filaments and controls neuronal outgrowth. We predict that human mutant FRMD7 thus influences Rac1 signaling activation, which can lead to abnormal neuronal outgrowth and cause the X-linked ICN.

CCG polymorphisms in the huntingtin gene have no effect on the pathogenesis of patients with Huntington's disease in mainland Chinese families.

Huntingtons disease (HD) is caused by the abnormal expansion of CAG repeats in the huntingtin gene (HTT). The adjacent proline-rich region, which also has a CCG polymorphism among people of different races, may also affect the pathogenesis of HD. To study the effect of this polymorphism on patients with HD in mainland China, 53 HD mutant alleles were examined. The results showed that 54.72% of the HD mutant alleles had 10-repeat alleles, and the remaining 45.28% had 7-repeat alleles. Moreover, comparison of the clinical features between the two groups revealed no significant difference. We also investigated its effect on the aggregates in vitro. No significant difference was detected when the morphology and size of the aggregates with the two polymorphisms was compared in cells. Given these findings, it was quite reasonable to suppose that the CCG polymorphism may not influence the pathogenesis of patients with HD in mainland China.

Spatial distribution of 5-hydroxymethyl cytosine in rat brain and temporal distribution in striatum.

Recently, 5-hydroxymethyl cytosine (5hmC) was identified in higher organisms as a novel epigenetic modification factor, and was found to be substantially enriched in the central nervous system relative to many other tissues and cell types. Additionally, epigenetic modifications are markedly involved in many neurological disorders. However, the precise role of 5hmC in the brain and neurological diseases remains elusive. To reveal its functional role, a general screen of its spatial and temporal distribution was proposed as being a reasonable starting investigation. Here, we found that 5hmC was widely distributed in the cerebral cortex, striatum, hippocampus, cerebellum, and the brain stem. At the cellular level, 5hmC was widely expressed in neurons and astrocytes even probably the majority of glial cells. Further, the content of 5hmC in different brain regions was inconsistent. Moreover, the pattern of 5hmC in the regions of the whole rat brain was highly susceptible to age-associated modifications. We also found similar phenomena in the striatum, which had not been previously studied. Also, unlike other brain regions, for example in the cerebellum and granulosa cells, 5hmC also appeared to display specific expression in these tissues. However, we didn’t obtain the expected result that 5hmC will be increased in 6-hydroxydopamine-induced models of Parkinson’s disease with regard the preliminary exploration of 5hmC in these models. Our results suggest that in rats and other mammals, 5hmC likely plays an important role in the brain and is associated with neural development and aging in different areas of the brain.

Essential sequence of the N-terminal cytoplasmic localization-related domain of huntingtin and its effect on huntingtin aggregates

Huntington’s disease (HD) is caused by abnormal CAG repeat expansion in the 5′-end of the Huntingtin (HTT) gene. In addition to the canonical C-terminal full-length huntingtin (htt) nuclear export signal, a cytoplasmic localization-related domain (CLRD) in the N-terminus of htt has recently been reported. Here, we analyzed this domain by introducing deletion and substitution mutations in a truncated N-terminal htt protein and subsequently monitored htt expression, aggregation and subcellular localization by immunocytochemistry and Western blot analysis. We demonstrated that Htt4–17 was the essential sequence for htt cytoplasmic localization. We also found that the subcellular distribution of htt was altered when Htt1–17 was mutated to contain amino acids of different charges, suggesting a structural requirement of Htt1–17 for the cytoplasmic localization of htt. Deletion of the first three amino acids did not affect its association with mitochondria. We observed that defective cytoplasmic localization resulted in a reduction of total htt aggregates and increased nuclear aggregates, indicating that the subcellular distribution of the protein might influence the aggregation process. These studies provide new insight into the molecular mechanism of htt aggregation in HD.

The ABCD2 score is better for stroke risk prediction after anterior circulation TIA compared to posterior circulation TIA

Objective: Transient ischemic attacks (TIAs) are divided into anterior and posterior circulation types (AC-TIA, PC-TIA, respectively). In the present study, we sought to evaluate the ABCD2 score for predicting stroke in either AC-TIA or PC-TIA. Methods: We prospectively studied 369 consecutive patients who presented with TIA between June 2009 and December 2012. The 7 d occurrence of stroke after TIA was recorded and correlated with the ABCD2 score with regards to AC-TIA or PC-TIA. Results: Overall, 273 AC-TIA and 96 PC-TIA patients were recruited. Twenty-one patients with AC-TIA and seven with PC-TIA developed a stroke within the subsequent 7 d (7.7% vs. 7.3%, p = 0.899). The ABCD2 score had a higher predictive value of stroke occurrence in AC-TIA (the AUC was 0.790; 95% CI, 0.677–0.903) than in PC-TIA (the AUC was 0.535; 95% CI, 0.350–0.727) and the z-value of two receiver operating characteristic (ROC) curves was 2.24 (p = 0.025). AC-TIA resulted in a higher incidence of both unilateral weakness and speech disturbance and longer durations of the symptoms. Inversely, PC-TIA was associated with a higher incidence of diabetes mellitus (19.8% vs. 10.6%, p = 0.022). Evaluating each component of scores, age ≥ 60 yr (OR = 7.010, 95% CI 1.599–30.743), unilateral weakness (OR = 3.455, 95% CI 1.131–10.559), and blood pressure (OR = 9.652, 95% CI 2.202–42.308) were associated with stroke in AC-TIA, while in PC-TIA, diabetes mellitus (OR = 9.990, 95% CI 1.895–52.650) was associated with stroke. Conclusion: In our study, the ABCD2 score could predict the short-term risk of stroke after AC-TIA, but might have limitation for PC-TIA.