Project description:The biological function and disease association of human endogenous retroviral (HERV) elements remains largely elusive. We addressed the physiological role of HERV-K(HML-2) in neuronal differentiation by manipulating HERV-K(HML-2) expression levels. We used CRISPR engineering to activate or repress HERV-K(HML-2) and demonstrate that elevated HERV-K(HML-2) transcription is detrimental for development, functionality and growth of cortical neurons. Effects are cell-type specific, as dopaminergic neurons were unaffected. We further show that layer formation is altered during forebrain organoid formation following activation of HERV-K(HML-2) transcription. HERV-K(HML-2) transcriptional activation concurrently elevated Neurotrophic Tyrosine Receptor Kinase 3 (NTRK3) expression along with other neurodegeneration-related genes. Direct transcriptional activation of NTRK3 resembled the HERV-K(HML-2) activation phenotype. Intriguingly, reduction of NTRK3 levels in HERV-K(HML-2)-activated cortical neurons restored differentiated cortical neurons. Hence, our findings unravel a unique cell type-specific mechanism of HERV-K(HML-2) during cortical neuronal differentiation.
Project description:Elevated transcript expression of the endogenous retrovirus family HERV-K (HML-2) is seen in the majority of breast cancers, although the identity of the individual loci contributing to this expression as well as their mechanism of activation is unclear. Using high-throughput next-generation sequencing techniques optimized for the capture of HML-2 expression, we produced a complete profile of the HML-2 transcriptome before and after human mammary epithelial cell transformation.
Project description:Human endogenous retroviruses (HERVs) occupy a large portion of the human genome. Most HERVs are transcriptionally silent, but can be reactivated during pathological states such as viral infection and certain cancers. The HERV-K HML-2 clade includes elements that recently have integrated in the human germ line and often contain intact open reading frames (ORFs) that possibly support peptide and protein expression. Understanding HERV-K-host interactions and their potential as biomarkers is problematic due to the high similarity among different elements. Previously we described a long-read single molecule real-time sequencing (PacBio) strategy to analyze HERV-K RNA expression profiles in different cell types. However, identifying HERV-K HML-2 proteins accurately is difficult without robust and reliable methods and reagents. Here we present a new approach to characterize the HML-2 elements that (a) are being translated and (b) produce enough protein to be detected and identified by mass spectrometry. Our data reveal that RNA expression profiling alone cannot accurately predict which HML-2 elements are responsible for protein production, as we observe several differences between the highest expressed RNAs and the elements that are the predominant source of HERV-K HML-2 protein synthesis. These studies represent an important advance towards untangling the complexity of HERV-K-host interactions.
Project description:The pluripotent stem cell (PSC)-derived human primordial germ cell-like cells (PGCLCs) are a cell culture-derived surrogate model of embryonic primordial germ cells. Upon differentiation of PSCs to PGCLCs, multiple loci of HML-2, the hominoid-specific human endogenous retrovirus (HERV), are strongly activated, which is necessary for PSC differentiation to PGCLCs. In PSCs, strongly ac-tivated loci of HERV-H family HERVs create chromatin contacts, which are required for the plu-ripotency. Chromatin contacts in the genome of human PSCs and PGCLCs were determined by Hi-C sequencing, and their locations were compared with those of HML-2 loci strongly activated in PGCLCs but silenced in the precursor naïve iPSCs. In both iPSCs and PGCLCs, the size of chromatin contacts were found to be around one megabase, which corresponds to the Topologically Associ-ated Domains in the human genome but is slightly larger in PGCLCs than iPSCs. The number of small-sized chromatin contacts diminished while numbers of larger-sized contacts increased. The distances between chromatin contacts newly formed in PGCLCs and the degrees of activation of the closest HML-2 loci showed significant inverse correlation. Our study provides evidence that strong activation of HML-2 provirus loci may be associated with newly formed chromatin contacts in their vicinity, potentially contributing to PSC differentiation to the germ cell lineage.
Project description:Identification of amyotrophic lateral sclerosis (ALS) associated genes. Post mortem spinal cord grey matter from sporadic and familial ALS patients compared with controls.
Project description:The purpose of this experiment was to compare the differences in transcript levels between RNA samples collected from fibroblasts from healthy control patients, amyotrophic lateral sclerosis (ALS) patients carrying an expanded GGGGCC repeat mutation in the chromosome 9 open reading frame 72 gene and ALS patients with a mutation in the SOD1 gene.
