NF1
Neurofibromin (Neurofibromatosis-related protein NF-1) [Contains: Neurofibromin truncated]
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The conditional reprogramming cell culture method was developed to facilitate growth of senescence-prone normal and neoplastic epithelial cells, and involves co-culture with irradiated fibroblasts and the addition of a small molecule Rho kinase (ROCK) inhibitor. The aim of this study was to determine whether this approach would facilitate the culture of compact low grade gliomas. We attempted to culture 4 pilocytic astrocytomas, 2 gangliogliomas, 2 myxopapillary ependymomas, 2 anaplastic gliomas, 2 difficult-to-classify low grade neuroepithelial tumors, a desmoplastic infantile ganglioglioma, and an anaplastic pleomorphic xanthoastrocytoma using a modified conditional reprogramming cell culture approach. Conditional reprogramming resulted in robust increases in growth for a majority of these tumors, with fibroblast conditioned media and ROCK inhibition both required. Switching cultures to standard serum containing media, or serum free neurosphere conditions, with or without ROCK inhibition, resulted in decreased proliferation and induction of senescence markers. ROCK inhibition and conditioned media both promoted Akt and Erk1/2 activation. Several cultures, including one derived from a NF1-associated pilocytic astrocytoma (JHH-NF1-PA1) and one from a BRAF p.V600E mutant anaplastic pleomorphic xanthoastrocytoma (JHH-PXA1), exhibited growth sufficient for preclinical testing in vitro. In addition, JHH-NF1-PA1 cells survived and migrated in larval zebrafish orthotopic xenografts, while JHH-PXA1 formed orthotopic xenografts in mice histopathologically similar to the tumor from which it was derived. These studies highlight the potential for the conditional reprogramming cell culture method to promote the growth of glial and glioneuronal tumors in vitro, in some cases enabling the establishment of long-term culture and in vivo models.
Keywords
- BRAFV600E
- Conditional reprogramming
- NF1
- Senescence
- low grade glioma
Recent studies have demonstrated circular RNAs (circRNAs) to be widely expressed and to have important physiological functions. However, the expression, regulation, and function of circRNAs in neuroglial cells are unknown. Herein, we characterized the expression, regulation, and function of circRNAs in astrocytes. Astrocyte circRNAs were identified by computational analysis of newborn SD rat primary astrocytes cultured with 20 g/L D-galactose. In this manner, 7376 circRNAs were identified, among which most circRNAs (5754) were derived from annot_exons, whereas 27 were antisense, 853 were exon/intron, 329 were intergenic, 41 were intronic, and 372 were one exon. Among these, [i]circNF1-419[/i] was demonstrated to regulate autophagy, in over-expressing [i]circNF1-419[/i] transfected astrocytes, through the PI3K-I/Akt-AMPK-mTOR and PI3K-I/Akt-mTOR signaling pathways. An adenovirus associated virus packaging system (virus titer 1 ×10 ), over-expressing [i]circNF1-419[/i] and injected into mouse cerebral cortex, showed autophagy enhancing activity by binding the proteins Dynamin-1 and Adaptor protein 2 B1 (AP2B1). This binding regulated aging markers (p21, p35/25, and p16) and inflammatory factors (TNF-α and NF-κB), and reduced the expression of Alzheimer's disease marker proteins (Tau, p-Tau, Aβ , and APOE), which delayed senile dementia. Transcriptome analysis of the brain showed that [i]circNF1-419[/i] improved other signaling pathways, especially those related to the synapses of SAMP8 mice. These findings provide novel insights into [i]circNF1-419[/i] and its potential usefulness for the diagnosis and treatment of dementia by regulating Dynamin-1 and AP2B1 mediated autophagy.
MeSH Terms
- Adaptor Protein Complex beta Subunits
- Aging
- Alzheimer Disease
- Animals
- Astrocytes
- Autophagy
- Cellular Senescence
- Dynamin I
- Genes, Neurofibromatosis 1
- Mice
- RNA, Circular
- Rats
- Rats, Sprague-Dawley
Keywords
- aging
- astrocyte
- autophagy
- biological function
- circular RNA
Neurofibromatosis type 1 (NF1) is a frequent genetic disease leading to the development of Schwann cell-derived neurofibromas or melanocytic lesions called café-au-lait macules (CALMs). The molecular mechanisms involved in CALMs formation remain largely unknown. In this report, we show for the first time pathophysiological mechanisms of abnormal melanocyte differentiation in a human NF1( /-) -induced pluripotent stem cell (iPSC)-based model. We demonstrate that NF1 patient-derived fibroblasts can be successfully reprogrammed in NF1( /-) iPSCs with active RAS signaling and that NF1 loss induces senescence during melanocyte differentiation as well as in patient's-derived CALMs, revealing a new role for NF1 in the melanocyte lineage.
MeSH Terms
- Adult
- Cell Differentiation
- Cellular Senescence
- Humans
- Induced Pluripotent Stem Cells
- Melanocytes
- Models, Biological
- Mutation
- Neurofibromin 1
- Signal Transduction
- ras Proteins
Keywords
- café-au-lait macules
- induced pluripotent stem cell
- melanocyte
- neurofibromatosis type 1
- oncogene-induced senescence
Oxidative stress and persistent activation of DNA damage response (DDR) are causally involved in the development of cellular senescence, a phenomenon implicated in fundamental (patho)physiological processes such as aging, fetal development and tumorigenesis. Here, we report that adenine nucleotide translocase-2 (ANT2) is consistently down-regulated in all three major forms of cellular senescence: replicative, oncogene-induced and drug-induced, in both normal and cancerous human cells. We previously reported formation of novel NF1/Smad transcription repressor complexes in growth-arrested fibroblasts. Here we show that such complexes form in senescent cells. Mechanistically, binding of the NF1/Smad complexes to the NF1-dependent repressor elements in the ANT2 gene promoter repressed ANT2 expression. Etoposide-induced formation of these complexes and repression of ANT2 were relatively late events co-incident with production and secretion of, and dependent on, TGF-β. siRNA-mediated knock-down of ANT2 in proliferating cells resulted in increased levels of reactive oxygen species (ROS) and activation of the DDR. Knock-down of ANT2, together with etoposide treatment, further intensified ROS production and DNA damage signaling, leading to enhanced apoptosis. Together, our data show that TGF-β-mediated suppression of ANT2 through NF1/Smad4 complexes contributes to oxidative stress and DNA damage during induction of cellular senescence.
MeSH Terms
- Adenine Nucleotide Translocator 2
- Cell Line
- Cell Nucleus
- Cellular Senescence
- Cytoprotection
- DNA Damage
- Down-Regulation
- Etoposide
- Humans
- Mutation
- NFI Transcription Factors
- Oxidative Stress
- Promoter Regions, Genetic
- Repressor Proteins
- Smad4 Protein
- Transforming Growth Factor beta
Keywords
- Adenine nucleotide translocase-2
- Nuclear factor 1
- Oxidative stress
- Senescence
- Smad
- Transforming growth factor-β
Cognitive performance is compromised in Neurofibromatosis type 1 (NF1) patients, but neuropsychological data including elderly NF1 are extremely sparse. We compared the cognitive performance of a small elderly NF1 group (n = 5) with an age-matched healthy control group (n = 49). NF1 group performed worse than control group on a global cognitive impairment task, verbal working memory, and visuospatial functioning. The results suggest that cognitive impairment is an important feature of NF1 across lifespan, including elderly individuals. Future studies approaching the NF1 cognitive profile might benefit from looking at the mechanisms linked to the age-related aspects of cognitive decline.
MeSH Terms
- Aged
- Case-Control Studies
- Executive Function
- Female
- Humans
- Male
- Memory, Short-Term
- Middle Aged
- Neurofibromatosis 1
Keywords
- Aging
- Cognition
- Elderly
- Neurofibromatosis type 1
- Neuropsychology
A third of patients with paraganglial tumors, pheochromocytoma, and paraganglioma, carry germline mutations in one of the susceptibility genes, RET, VHL, NF1, SDHAF2, SDHA, SDHB, SDHC, SDHD, TMEM127, and MAX. Despite increasing importance, data for long-term prognosis are scarce in pediatric presentations. The European-American-Pheochromocytoma-Paraganglioma-Registry, with a total of 2001 patients with confirmed paraganglial tumors, was the platform for this study. Molecular genetic and phenotypic classification and assessment of gene-specific long-term outcome with second and/or malignant paraganglial tumors and life expectancy were performed in patients diagnosed at <18 years. Of 177 eligible registrants, 80% had mutations, 49% VHL, 15% SDHB, 10% SDHD, 4% NF1, and one patient each in RET, SDHA, and SDHC. A second primary paraganglial tumor developed in 38% with increasing frequency over time, reaching 50% at 30 years after initial diagnosis. Their prevalence was associated with hereditary disease (P=0.001), particularly in VHL and SDHD mutation carriers (VHL vs others, P=0.001 and SDHD vs others, P=0.042). A total of 16 (9%) patients with hereditary disease had malignant tumors, ten at initial diagnosis and another six during follow-up. The highest prevalence was associated with SDHB (SDHB vs others, P<0.001). Eight patients died (5%), all of whom had germline mutations. Mean life expectancy was 62 years with hereditary disease. Hereditary disease and the underlying germline mutation define the long-term prognosis of pediatric patients in terms of prevalence and time of second primaries, malignant transformation, and survival. Based on these data, gene-adjusted, specific surveillance guidelines can help effective preventive medicine.
MeSH Terms
- Adolescent
- Adrenal Gland Neoplasms
- Child
- Child, Preschool
- DNA, Neoplasm
- Female
- Genetic Predisposition to Disease
- Germ-Line Mutation
- Humans
- Kaplan-Meier Estimate
- Life Expectancy
- Longitudinal Studies
- Male
- Paraganglioma
- Pheochromocytoma
- Sequence Analysis, DNA
Keywords
- germline mutations
- long-term follow-up
- pheochromocytoma
- relapse