Hong, R. | Search bioRxiv

bioRxiv2019

Improving the specificity of adenine base editor using high-fidelity Cas9

Adenine base editor (ABE) mediates the conversion of A to G in genomic DNA. In human, approximately 47.8% of known pathogenic SNPs can be corrected by A to G conversion, indicating that ABE have tremendous potential in gene therapy. However, the off-target activity of ABE limits its clinical application. ABE off-target activity in DNA is depended on the bonding of Streptococcus pyogenes Cas9 (SpCas9) on off-target sites [1, 2]. Therefore, using high-fidelity Cas9 should be able to improve the specificity of ABE. Based on this, we replaced the wild-type SpCas9 in ABE7.10 with four high-fidelity Cas9s to improve its specificity. The analysis of target deep sequencing data demonstrate that the specificity of e-ABE is substantially improved compared to conventional ABE7.10 in four test sites. But the broad editing window of ABE hampers its application, ABE needs to be optimized to get variants with narrow editing window.

biochemistry↗

bioRxiv2019

A Single-Cell Immune Atlas of Triple Negative Breast Cancer Reveals Novel Immune Cell Subsets

Triple-negative breast cancer (TNBC) represents the most aggressive breast cancer subtype, which recently attracts great interest for immune therapeutic development. In this context, in-depth understanding of TNBC immune landscape is highly demanded. Here we report single-cell RNA sequencing results of 9683 tumor-infiltrated immune cells isolated from 14 treatment naive TNBC tumors, where 22 immune cell subsets, including T cells, macrophages, B cells, and DCs have been characterized. We identify a new T cell subset, CD8+CXCL8+ naive T cell, which associates with poor survival. A novel immune cell subset comprised of TCR+ macrophages, is found to be widely distributed in TNBC tumors. Further analyses reveal an up-regulation of molecules associated with TCR signaling and cytotoxicity in these immune cells, indicating TCR signaling activation. Altogether, our study provides a valuable resource to understand the immune ecosystem of TNBC. The novel immune cell subsets reported herein might be functionally important in cancer immunity.\n\nSIGNIFICANCEThis work demonstrates a single-cell transcriptome atlas of immune cells in treatment naive TNBC tumors, revealing novel immune cell subsets. This study provides a valuable resource to understand the immune ecosystem of TNBC, which will be helpful for the immunotherapeutic strategy design of TNBC.

immunology↗