Faculty Opinions recommendation of Single-neuron sequencing analysis of L1 retrotransposition and somatic mutation in the human brain.

Author(s):  
Tao Cai
Cell ◽  
2012 ◽  
Vol 151 (3) ◽  
pp. 483-496 ◽  
Author(s):  
Gilad D. Evrony ◽  
Xuyu Cai ◽  
Eunjung Lee ◽  
L. Benjamin Hills ◽  
Princess C. Elhosary ◽  
...  

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Gilad D Evrony ◽  
Eunjung Lee ◽  
Peter J Park ◽  
Christopher A Walsh

Whether somatic mutations contribute functional diversity to brain cells is a long-standing question. Single-neuron genomics enables direct measurement of somatic mutation rates in human brain and promises to answer this question. A recent study (<xref ref-type="bibr" rid="bib65">Upton et al., 2015</xref>) reported high rates of somatic LINE-1 element (L1) retrotransposition in the hippocampus and cerebral cortex that would have major implications for normal brain function, and suggested that these events preferentially impact genes important for neuronal function. We identify aspects of the single-cell sequencing approach, bioinformatic analysis, and validation methods that led to thousands of artifacts being interpreted as somatic mutation events. Our reanalysis supports a mutation frequency of approximately 0.2 events per cell, which is about fifty-fold lower than reported, confirming that L1 elements mobilize in some human neurons but indicating that L1 mosaicism is not ubiquitous. Through consideration of the challenges identified, we provide a foundation and framework for designing single-cell genomics studies.


2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S33-S34
Author(s):  
Karen Ocwieja ◽  
Alexandra Stanton ◽  
Alexsia Richards ◽  
Jenna Antonucci ◽  
Travis Hughes ◽  
...  

Abstract Background The molecular mechanisms underpinning the neurologic and congenital pathologies caused by Zika virus (ZIKV) infection remain poorly understood. One barrier has been the lack of relevant model systems for the developing human brain; however, thanks to advances in the stem cell field, we can now evaluate ZIKV central nervous system infections in human stem cell-derived cerebral organoids which recapitulate complex 3-dimensional neural architecture. Methods We apply Seq-Well—a simple, portable platform for massively parallel single-cell RNA sequencing—to characterize cerebral organoids infected with ZIKV. Using this sequencing method, and published transcriptional profiles, we identify multiple cellular populations in our organoids, including neuroprogenitor cells, intermediate progenitor cells, and terminally differentiated neurons. We detect and quantify host mRNA transcripts and viral RNA with single-cell resolution, defining transcriptional features of uninfected cells and infected cells. Results In this model of the developing brain, we identify preferred tropisms of ZIKV infection and pronounced effects on cell division, differentiation, and death. Our data additionally reveal differences in cellular populations and gene expression within organoids infected by historic and contemporary ZIKV strains from a variety of geographic locations. This finding might help explain phenotypic differences attributed to the viruses, including variable propensity to cause microcephaly. Conclusion Overall, our work provides insight into normal and diseased human brain development, and suggests that both virus replication and host response mechanisms underlie the neuropathology of ZIKV infection. Disclosures All Authors: No reported Disclosures.


2019 ◽  
Vol 28 (R2) ◽  
pp. R197-R206 ◽  
Author(s):  
Michael A Lodato ◽  
Christopher A Walsh

AbstractAging is a mysterious process, not only controlled genetically but also subject to random damage that can accumulate over time. While DNA damage and subsequent mutation in somatic cells were first proposed as drivers of aging more than 60 years ago, whether and to what degree these processes shape the neuronal genome in the human brain could not be tested until recent technological breakthroughs related to single-cell whole-genome sequencing. Indeed, somatic single-nucleotide variants (SNVs) increase with age in the human brain, in a somewhat stochastic process that may nonetheless be controlled by underlying genetic programs. Evidence from the literature suggests that in addition to demonstrated increases in somatic SNVs during aging in normal brains, somatic mutation may also play a role in late-onset, sporadic neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. In this review, we will discuss somatic mutation in the human brain, mechanisms by which somatic mutations occur and can be controlled, and how this process can impact human health.


2021 ◽  
Vol 108 (Supplement_1) ◽  
Author(s):  
M Ita ◽  
Y Nolan ◽  
A Toulouse ◽  
JH Wang ◽  
CH Lim ◽  
...  

Abstract Background Comprehensive molecular profiling of gliomas provide information essential for accurate biological classification beyond traditional histopathology. Genomic profiling utilizing tumour tissue samples inevitably involves obtaining tissues through potentially hazardous surgical procedures or stereotactic biopsies carrying risks of morbidity and mortality. Tissues from biopsies may also be insufficient or fail to capture a comprehensive picture of the tumours genetic profile due to tumour heterogeneity. In these contexts, complementary minimally invasive strategies are needed for molecular profiling of gliomas. Cell free DNA (cfDNA) has emerged as an easily accessible biomarker containing fragments of circulating tumour DNA (ctDNA) released into plasma through apoptosis. We explored its potential utility in genomic profiling of brain tumours. Method Plasma cfDNA from patients with radiographically suspected brain malignancies were extracted and quantified before planned surgical interventions. Cell free DNA was extracted using a QIAamp Circulating Nucleic Acid Kit (Qiagen), and was quantified (ng cfDNA/mL) using a DS-11 FX Spectrophotometer (DeNovix). Pathway focused profiling of somatic mutation status was performed using QBiomarker Somatic Mutation PCR Arrays for human brain cancers (Qiagen) through real time PCR (Roche). Result Somatic mutations in human brain cancer were evaluated in the following genes; BRAF, CTNNB1/beta-catenin, EGFR, IDH1, IDH2, KRAS, NF2, NRAS, PIK3CA, and PTEN. A total of 14 (70%) patients had greater than 1 somatic mutation detected in their plasma cfDNA. Conclusion We postulate that glioma derived circulating tumour DNA occur in plasma, and genomic analysis using cell free DNA may complement current methods of glioma genomic characterisation. Take-home message Glioma derived circulating tumour DNA occur in plasma.


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