[Abstract] Objective: To screen candidate epitopes of breast cancer HLA-A2 restrictive neoantigen and to identify high frequency mutation sites in breast cancer neoantigen by using bioinformatics method. Methods: NCBI and GDC databases were used to search missense mutation sites formed by single nucleotide mutation in breast cancer among reported literatures and sequencing data. The new antigen epitopes were predicted by HLA-A2 antigen epitope prediction website BIMAS, SYFPEITHI and artificial neural networkbased NetMHC4.0, and the epitopes with TAP binding power less than Intermediate were eliminated. The candidate epitopes were prioritized by mutation frequency and prediction results. Results: A total of 17 high-frequency mutation genes, including BTLA, ERBB2 and NBPF12 etc, were screened by the above-mentioned methods, and a total of 26 neoantigen epitopes were identified. The binding power of epitopes predicted using BIMAS and SYFPEITHI showed great difference (P<0.05), epitopes in high priority as GSTP1 (A114V , mutation frequency of 5.94%) and BRCA2 (N991H, mutation frequency of 5.40%) etc, were expected to be candidate neo-antigen epitopes; however, their mutation frequency was relatively too low to achieve“universal use” . The possibility of these epitopes used as general breast cancer neo-antigen epitopes is less likely. Conclusion: The common mutation frequency of breast cancer is lower than that of other tumors; it ’s difficult to find“universal”new antigen epitopes of breast cancer; the individualized neoantigen vaccine may be of more promise, which needs further research.

Medium spiny neurons (MSNs) in the striatum, which can be divided into D1 and D2 MSNs, originate from the lateral ganglionic eminence (LGE). Previously, we reported that Six3 is a downstream target of Sp8/Sp9 in the transcriptional regulatory cascade of D2 MSN development and that conditionally knocking out Six3 leads to a severe loss of D2 MSNs. Here, we showed that Six3 mainly functions in D2 MSN precursor cells and gradually loses its function as D2 MSNs mature. Conditional deletion of Six3 had little effect on cell proliferation but blocked the differentiation of D2 MSN precursor cells. In addition, conditional overexpression of Six3 promoted the differentiation of precursor cells in the LGE. We measured an increase of apoptosis in the postnatal striatum of conditional Six3-knockout mice. This suggests that, in the absence of Six3, abnormally differentiated D2 MSNs are eliminated by programmed cell death. These results further identify Six3 as an important regulatory element during D2 MSN differentiation.

Mouse cortical radial glial cells (RGCs) are primary neural stem cells that give rise to cortical oligodendrocytes, astrocytes, and olfactory bulb (OB) GABAergic interneurons in late embryogenesis. There are fundamental gaps in understanding how these diverse cell subtypes are generated. Here, by combining single-cell RNA-Seq with intersectional lineage analyses, we show that beginning at around E16.5, neocortical RGCs start to generate ASCL1