Role of SOX2 mutations in human hippocampal malformations and epilepsy

PURPOSE: Seizures are noted in a significant proportion of cases of de novo, heterozygous, loss-of-function mutations in SOX2, ascertained because of severe bilateral eye malformations. We wished to determine the underlying cerebral phenotype in SOX2 mutation and to test the candidacy of SOX2 as a gene contributing to human epilepsies. METHODS: We examined high-resolution MRI scans in four patients with SOX2 mutations, two of whom had seizures. We determined the Sox2 expression pattern in developing murine brain. We searched for SOX2 mutation in 24 patients with typical hippocampal sclerosis and for common variations in SOX2 in 655 patients without eye disease but with epilepsy, including 91 patients with febrile seizures, 93 with hippocampal sclerosis, and 258 with temporal lobe epilepsy. RESULTS: Striking hippocampal and parahippocampal malformations were seen in all cases, with a history of febrile seizures or epilepsy in two of four cases. The Sox2 expression pattern in developing mouse brain supports the pattern of malformations observed. Mutation screening in patients with epilepsy did not reveal any abnormalities in SOX2. No associations were found between any clinical epilepsy phenotype and common variation in SOX2. CONCLUSIONS: SOX2 haploinsufficiency causes mesial temporal malformation in humans, making SOX2 dysfunction a candidate mechanism for mesial temporal abnormalities associated with chronic epilepsy. However, although mutation of SOX2 in humans causes hippocampal malformation, SOX2 mutation or variation is unlikely to contribute commonly to mesial temporal lobe epilepsy or its structural (hippocampal sclerosis) or historic (febrile seizures) associations in humans.     

SOX1 antibodies in sera from patients with paraneoplastic neurological syndromes

Objectives – SOX1 antibodies have been described in patients with Lambert–Eaton myasthenic syndrome (LEMS) in association with voltage‐gated calcium channel antibodies as serological markers of small cell lung cancer (SCLC). This study was aimed to screen for additional SOX1 autoimmunity in onconeural antibody‐positive sera from patients with paraneoplastic neurological syndromes (PNS) other than LEMS and to identify the clinical–immunological profile and associated tumours of patients with coexisting SOX1 antibodies. Methods– We retrospectively analysed sera from 55 patients with different PNS positive for well‐characterized antineuronal antibodies for the presence of SOX1 antibodies by recombinant ELISA and immunoblot. Results– Eight (14.5%) patients showed additional SOX1 antibodies in the ELISA and the recombinant immunoblot. Five patients had coexisting Hu antibodies, while the other three showed coexisting CV2/CRMP5, amphiphysin, and coexisting CV2/CRMP5 and Hu antibodies, respectively. PNS included (partially overlapping) subacute sensory neuropathy, subacute sensorimotor neuropathy, cerebellar degeneration, brainstem encephalitis, encephalomyelitis and limbic encephalitis. No tumour was detected in two patients, while the others had lung cancer (four SCLC and two non‐SCLC). One patient showed SOX1‐specific intrathecal antibody synthesis. Conclusions– We describe SOX1 reactivity for the first time overlapping with CV2/CRMP5 and amphiphysin antibodies. SOX1 reactivity is predominantly associated with Hu antibodies and SCLC, but can occur also in other types of lung cancer. Neurological manifestations present in patients with coexisting SOX1 antibodies and well‐characterized antineuronal antibodies do not differ from those previously described in patients positive for antineuronal antibodies but no SOX1‐specific anti‐glial antibodies.     

SOX2基因在胶质瘤中的表达及生物学作用

目的 探讨SOX2基因在人胶质瘤中的表达水平、甲基化状态以及生物学作用。方法 选取人胶质瘤组织标本108例,正常脑组织30例。采用PCR的方法检测SOX2基因的表达水平和甲基化状态。MTT和软琼脂集落形成试验检测SOX2对胶质瘤U87和U251细胞的生物学作用。结果 SOX2在正常脑组织中的相对表达水平明显低于胶质瘤组织（PP<0.01）。过量表达sox2基因可促进胶质瘤u87和u251细胞增殖和集落形成能力。>结论 SOX2基因在胶质瘤组织高表达,其在胶质瘤中的表达水平可能受启动子区域甲基化状态影响,SOX2基因影响胶质瘤的肿瘤学特性。     

Gait disturbance in a patient with de novo 1.0-kb SOX2 microdeletion

BackgroundSex-determining region Y-box 2 (SOX2) plays an important role in the early embryogenesis of the eye, forebrain, and hypothalamic–pituitary axis. Anophthalmia, microphthalmia, and hormonal abnormalities are commonly observed in patients with SOX2-related disorders. Although gait disturbance, particularly ataxic gait, has recently been observed in several cases, detailed data regarding the clinical course of gait disturbance in SOX2-related disorders are limited.Case reportA 9-year-old Japanese boy presented with focal dyskinesia only during walking and running after he started walking at the age of 3 years. He also exhibited intellectual disability and mild dysmorphic features, including microcephaly, micropenis, and short stature associated with hormonal abnormalities. Gait disturbance with involuntary extremity movements only during walking and running was indicative of choreoathetosis and dystonia. Genetic analysis detected a de novo heterozygous 1.0-kb deletion including SOX2 at 3q26.32, as described in a previous technical paper.ConclusionsSOX2-related disorders should be considered in patients with some anomalies having a differential diagnosis of dyskinesia. Focal dyskinesia only during walking and running may be a characteristic feature of SOX2-related disorders.     

Epigenetic modifications of SOX2 enhancers, SRR1 and SRR2, correlate with in vitro neural differentiation

SOX2 is a key neurodevelopmental gene involved in maintaining the pluripotency of stem cells and proliferation of neural progenitors and astroglia. Two evolutionally conserved enhancers, SRR1 and SRR2, are involved in controlling SOX2 expression during neurodevelopment; however, the molecular mechanisms regulating their activity are not known. We have examined DNA methylation and histone H3 acetylation at both enhancers in NT2-D1 progenitors, neurons and astrocytes, to establish the role of epigenetic mechanisms in cell-type-specific SOX2 expression. This study showed that 1) unmethylated DNA and acetylated histones at both enhancers correlated with a high level of SOX2 expression in proliferating neural progenitors and 2) reversible modifications of the SRR1 element were observed during gene reexpression in astrocytes, whereas permanent epigenetic marks on the SRR2 enhancer were seen in neurons where the gene was silenced. Taken together, these results are clear illustrations of cell-type-specific epigenomes and suggest mechanisms by which they may be created and maintained.     

Connexin 32 promoter P2 mutations: a mechanism of peripheral nerve dysfunction

We identified a large Charcot-Marie-Tooth disease family with a novel mutation in the Connexin 32 (Cx32) P2 promoter region at position -526bp. This mutation was in a highly conserved SOX10 binding site. Functional studies were conducted on the Cx32 promoter that showed that this mutation reduced the activity of the Cx32 promoter and the affinity for SOX10 binding. These data suggest that interaction between the Cx32 P2 promoter, SOX10, and EGR2 highlight a mechanism of peripheral nerve dysfunction.     

miR-21 promotes the differentiation of hair follicle-derived neural crest stem cells into Schwann cells

Hair follicle-derived neural crest stem cells can be induced to differentiate into Schwann cells in vivo and in vitro. However, the underlying regulatory mechanism during cell differentiation remains poorly understood. This study isolated neural crest stem cells from human hair follicles and induced them to differentiate into Schwann cells. Quantitative RT-PCR showed that microRNA(miR)-21 expression was gradually increased during the differentiation of neural crest stem cells into Schwann cells. After transfection with the miR-21 agonist(agomir-21), the differentiation capacity of neural crest stem cells was enhanced. By contrast, after transfection with the miR-21 antagonist(antagomir-21), the differentiation capacity was attenuated. Further study results showed that SOX-2 was an effective target of miR-21. Without compromising SOX2 mRNA expression, miR-21 can down-regulate SOX protein expression by binding to the 3′-UTR of miR-21 mRNA. Knocking out the SOX2 gene from the neural crest stem cells significantly reversed the antagomir-21 inhibition of neural crest stem cells differentiating into Schwann cells. The results suggest that miR-21 expression was increased during the differentiation of neural crest stem cells into Schwann cells and miR-21 promoted the differentiation through down-regulating SOX protein expression by binding to the 3′-UTR of SOX2 mRNA.     

SOX7 interferes with β‐catenin activity to promote neuronal apoptosis

SOX7 mediates various developmental processes. However, its role in neuronal apoptosis remains unclear. In the present study, we investigated the expression pattern and role of SOX7 in potassium deprivation‐induced rat cerebellar granule neuron apoptosis. Our results showed that both mRNA and protein levels of SOX7 were upregulated when potassium was deprived. SOX7 overexpression promoted neuronal apoptosis, whereas knockdown of SOX7 protected neurons against apoptosis. Moreover, we found that β‐catenin activity was suppressed during apoptosis and that β‐catenin inhibition was crucial for potassium deprivation‐induced neuronal apoptosis. This suppression was mediated by an interaction between SOX7 and β‐catenin but not by protein degradation. Lastly, we showed that β‐catenin inhibition mediated the pro‐apoptotic effect of SOX7. Together, our findings demonstrated that SOX7 interfered with β‐catenin activity to promote neuronal apoptosis, which acted as a novel signaling mechanism in neuronal cell death.     

脑胶质瘤SOX7基因的甲基化状态及临床意义

目的 探讨脑胶质瘤SOX7基因的甲基化状态及其与病人预后的关系。方法 收集2013年6月至2015年1月手术切除的胶质瘤标本131例,另取颅脑损伤内减压术中切除的正常脑组织标本32例作为对照。应用甲基化特异PCR及RT-PCR方法检测SOX7基因的甲基化状态及mRNA表达水平。采用Kplan-Meier法分析生存曲线。结果 胶质瘤SOX7基因甲基化率（71.8%,94/131）明显高于正常脑组织（32.4%,11/34;P<0.05）。高级别胶质瘤SOX7甲基化率（81.01%,64/79）明显高于低级别胶质瘤（57.69%,30/52）。胶质瘤SOX7 mRNA水平明显低于正常脑组织（P<0.05）。SOX7基因甲基化组生存期较非甲基化组明显缩短（P<0.01）。结论 胶质瘤SOX7基因甲基化率升高,SOX7在胶质瘤中表达水平下调,SOX7基因的甲基化状态与病人生存期密切相关。     

Extrinsic coagulation pathway activation and metalloproteinase-2/TIMPs system are related to oxidative stress and atherosclerosis in hemodialysis patients

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), together with extrinsic coagulation pathway activation and increased oxidative stress (SOX) have all been implicated as important factors in atherosclerosis and vascular remodelling. The aim of the present study was to investigate whether the MMPs/TIMPs system is associated with activation of the extrinsic coagulation pathway in conditions of increased SOX in hemodialysis (HD) patients. In HD patients, with and without cardiovascular disease (CVD), and in controls, we compared pre-dialysis levels of MMP-2, MMP-9,TIMP-1,TIMP-2; the markers of extrinsic coagulation pathway-tissue factor (TF) and its inhibitor (TFPI), prothrombin fragment F1+2 (F1+2); a marker of SOX-Cu/Zn superoxide dismutase (Cu/Zn SOD) and a surrogate of atherosclerotic disease-intima media thickness (IMT). Hemodialysis patients, particularly those with CVD, showed a significant increase in values of MMP-2/TIMPs, markers of the extrinsic coagulation pathway, Cu/Zn SOD and IMT as compared to controls. The markers of coagulation activation positively correlated with the MMP-2/TIMPs system, whereas they did not correlate with MMP-9. In addition, both MMP-2/TIMPs as well as extrinsic coagulation parameters were related to the prevalence of increased SOX, IMT and CVD. Multiple stepwise regression analysis showed that low TIMP-2 followed by increased Cu/Zn SOD and MMP-2 levels independently and significantly predicted elevated IMT on maintenance HD patients. In conclusion, our data suggest that the MMP-2/TIMPs system and an activated extrinsic coagulation pathway could cooperate in conditions of elevated SOX and could influence arterial remodeling resulting in the presence of CVD in haemodialysis patients.