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1. chinaXiv:201605.01735 [pdf]

PTEN deficiency reprogrammes human neural stem cells towards a glioblastoma stem cell-like phenotype

Duan, Shunlei; Yuan, Guohong; Ren, Ruotong; Xu, Xiuling; Fu, Lina; Li, Ying; Yang, Jiping; Zhang, Weiqi; Liu, Guang-Hui; Liu, Xiaomeng; Li, Jingyi; Tang, Fuchou; Ren, Ruotong; Bai, Ruijun; Liu, Guang-Hui; Ren, Ruotong; Bai, Ruijun; Qu, Jing; Zhang, Weizhou; Wu, Jun
Subjects: Biology >> Biophysics

PTEN is a tumour suppressor frequently mutated in many types of cancers. Here we show that targeted disruption of PTEN leads to neoplastic transformation of human neural stem cells (NSCs), but not mesenchymal stem cells. PTEN-deficient NSCs display neoplasm-associated metabolic and gene expression profiles and generate intracranial tumours in immunodeficientmice. PTEN is localized to the nucleus in NSCs, binds to the PAX7 promoter through association with cAMP responsive element binding protein 1 (CREB)/CREB binding protein (CBP) and inhibits PAX7 transcription. PTEN deficiency leads to the upregulation of PAX7, which in turn promotes oncogenic transformation of NSCs and instates 'aggressiveness' in human glioblastoma stem cells. In a large clinical database, we find increased PAX7 levels in PTEN-deficient glioblastoma. Furthermore, we identify that mitomycin C selectively triggers apoptosis in NSCs with PTEN deficiency. Together, we uncover a potential mechanism of how PTEN safeguards NSCs, and establish a cellular platform to identify factors involved in NSC transformation, potentially permitting personalized treatment of glioblastoma.

submitted time 2016-05-15 Hits2453Downloads886 Comment 0

2. chinaXiv:201605.01305 [pdf]

Age-related formaldehyde interferes with DNA methyltransferase function, causing memory loss in Alzheimer's disease

Tong, Zhiqian; Han, Chanshuai; Qiang, Min; Wu, Beibei; Su, Tao; Liu, Ying; He, Rongqiao; Tong, Zhiqian; Wang, Xiaomin; He, Rongqiao; Han, Chanshuai; Qiang, Min; Wu, Beibei; Su, Tao; Wang, Weishan; Lv, Jihui; Zhang, Shouzi; Luo, Wenhong; Li, Hui; Luo, Hongjun
Subjects: Biology >> Biophysics

Hippocampus-related topographic amnesia is the most common symptom of memory disorders in Alzheimer's disease (AD) patients. Recent studies have revealed that experience-mediated DNA methylation, which is regulated by enzymes with DNA methyltransferase (DNMT) activity, is required for the formation of recent memory as well as the maintenance of remote memory. Notably, overexpression of DNMT3a in the hippocampus can reverse spatial memory deficits in aged mice. However, a decline in global DNA methylation was found in the autopsied hippocampi of patients with AD. Exactly, what endogenous factors that affect DNA methylation still remain to be elucidated. Here, we report a marked increase in endogenous formaldehyde levels is associated with a decline in global DNA methylation in the autopsied hippocampus from AD patients. In vitro and in vivo results show that formaldehyde in excess of normal physiological levels reduced global DNA methylation by interfering DNMTs. Interestingly, intrahippocampal injection of excess formaldehyde before spatial learning in healthy adult rats can mimic the learning difficulty of early stage of AD. Moreover, injection of excess formaldehyde after spatial learning can mimic the loss of remote spatial memory observed in late stage of AD. These findings suggest that aging-associated formaldehyde contributes to topographic amnesia in AD patients. (C) 2015 Elsevier Inc. All rights reserved.

submitted time 2016-05-11 Hits842Downloads529 Comment 0

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