Project description:X1 is the most abundant transcript variant of BRAF mRNA and has a long 3’UTR, but its involvement in post-transcriptional regulatory circuits has not been investigated yet. Here, we describe 20 microRNAs that bind directly to the X1 3’UTR. They were identified in BRAFV600E mutant A375 melanoma cells using miR-CATCHv2.0, an implemented experimental method that combines RNA affinity purification with small RNA sequencing and an ad hoc analytical workflow. X1-targeting microRNAs fall into 4 classes, according to the effect that they exert (decrease/increase in BRAFV600E mRNA and protein levels) and on the mechanism they use to achieve it (destabilization/stabilization of X1 mRNA or decrease/increase in its translation). In many cases, the microRNA-induced variations in BRAFV600E protein levels are coupled to consistent variations in pMEK levels and, in turn, to melanoma cell proliferation and sensitivity to the BRAF inhibitor vemurafenib. However, examples exist of microRNAs that uncouple the degree of activation of the ERK pathway from the levels of BRAFV600E protein. Our study describes miR-CATCHv2.0 as an effective tool for the identification of direct microRNA-target interactions and unveils the complexity of the post-transcriptional regulation to which BRAFV600E and the ERK pathway are subjected in melanoma cells.
Project description:X1 is the most abundant transcript variant of BRAF mRNA and has a long 3’UTR, but its involvement in post-transcriptional regulatory circuits has not been investigated yet. Here, we describe 20 microRNAs that bind directly to the X1 3’UTR. They were identified in BRAFV600E mutant A375 melanoma cells using miR-CATCHv2.0, an implemented experimental method that combines RNA affinity purification with small RNA sequencing and an ad hoc analytical workflow. X1-targeting microRNAs fall into 4 classes, according to the effect that they exert (decrease/increase in BRAFV600E mRNA and protein levels) and on the mechanism they use to achieve it (destabilization/stabilization of X1 mRNA or decrease/increase in its translation). In many cases, the microRNA-induced variations in BRAFV600E protein levels are coupled to consistent variations in pMEK levels and, in turn, to melanoma cell proliferation and sensitivity to the BRAF inhibitor vemurafenib. However, examples exist of microRNAs that uncouple the degree of activation of the ERK pathway from the levels of BRAFV600E protein. Our study describes miR-CATCHv2.0 as an effective tool for the identification of direct microRNA-target interactions and unveils the complexity of the post-transcriptional regulation to which BRAFV600E and the ERK pathway are subjected in melanoma cells.
Project description:Lentiviral vector (LV)-based gene therapy holds promise for a broad range of diseases. Analyzing more than 280,000 vector integration sites (VISs) in 273 samples from 10 patients with X-linked severe combined immunodeficiency (SCID-X1), we discovered shared LV integrome signatures in 9 out of 10 patients in relation to the genomics, epigenomics, and 3D structure of the human genome. VISs were enriched in the nuclear sub-compartment A1 and integrated into super-enhancers close to nuclear pore complexes. These signatures were validated in T cells transduced with an LV encoding a CD19-specific chimeric antigen receptor. Intriguingly, the one patient whose VISs deviated from the identified integrome signatures had a distinct clinical course. Comparison of LV and gamma retrovirus integromes regarding their 3D genome signatures, identified differences that might explain the lower risk of insertional mutagenesis in LV-based gene therapy. Our findings suggest that LV integrome signatures, shaped by common features such as genome organization, may impact the efficacy of LV-based cellular therapies.