A High Intrinsic Peculiarity Rate Among Type Ia Supernovae

We have compiled a sample of 45 Type Ia supernovae (SNe Ia) discovered by the Lick Observatory Supernova Search (LOSS) and the Beijing Astronomical Observatory Supernova Survey (BAOSS), and determined the rate of spectroscopically peculiar SNe Ia (i.e., SN 1986G-like, SN 1991bg-like, and SN 1991T-like objects) and the luminosity function of SNe Ia. Because of the nature of the two surveys (distance-limited with small baselines and deep limiting magnitudes), nearly all SNe Ia have been discovered in the sample galaxies of LOSS and BAOSS; thus, the observed peculiarity rate and luminosity function of SNe Ia are intrinsic. We find that 36$\pm$9% of nearby SNe Ia are peculiar; specifically, the luminosity function of SNe Ia consists of 20% SN 1991T-like, 64% normal, and 16% SN 1991bg-like objects. We have compared our results to those found by earlier studies, and to those found at high redshift. The apparent dearth of SN 1991T-like objects at high redshift may be due to extinction, and especially to the difficulty of recognizing them from spectra obtained past maximum brightness or from spectra with low signal-to-noise ratios. Implications of the high peculiarity rate for the progenitor systems of SNe Ia are also briefly discussed.Comment: 20 pages, 7 figures, accepted for publication in the Ap

Shear-induced Notch-Cx37-p27 axis arrests endothelial cell cycle to enable arterial specification

Establishment of a functional vascular network is rate-limiting in embryonic development, tissue repair and engineering. During blood vessel formation, newly generated endothelial cells rapidly expand into primitive plexi that undergo vascular remodeling into circulatory networks, requiring coordinated growth inhibition and arterial-venous specification. Whether the mechanisms controlling endothelial cell cycle arrest and acquisition of specialized phenotypes are interdependent is unknown. Here we demonstrate that fluid shear stress, at arterial flow magnitudes, maximally activates NOTCH signaling, which upregulates GJA4 (commonly, Cx37) and downstream cell cycle inhibitor CDKN1B (p27). Blockade of any of these steps causes hyperproliferation and loss of arterial specification. Re-expression of GJA4 or CDKN1B, or chemical cell cycle inhibition, restores endothelial growth control and arterial gene expression. Thus, we elucidate a mechanochemical pathway in which arterial shear activates a NOTCH-GJA4-CDKN1B axis that promotes endothelial cell cycle arrest to enable arterial gene expression. These insights will guide vascular regeneration and engineering

Combining radiation and the ATR inhibitor berzosertib activates STING signaling and enhances immunotherapy via inhibiting SHP1 function in colorectal cancer

Abstract Background Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 (PD‐1) and programmed death‐ligand 1 (PD‐L1) have shown a moderate response in colorectal cancer (CRC) with deficient mismatch repair (dMMR) functions and poor response in patients with proficient MMR (pMMR). pMMR tumors are generally immunogenically “cold”, emphasizing combination strategies to turn the “cold” tumor “hot” to enhance the efficacy of ICIs. ATR inhibitors (ATRi) have been proven to cooperate with radiation to promote antitumor immunity, but it is unclear whether ATRi could facilitate the efficacy of IR and ICI combinations in CRCs. This study aimed to investigate the efficacy of combining ATRi, irradiation (IR), and anti‐PD‐L1 antibodies in CRC mouse models with different microsatellite statuses. Methods The efficacy of combining ATRi, IR, and anti‐PD‐L1 antibodies was evaluated in CRC tumors. The tumor microenvironment and transcriptome signatures were investigated under different treatment regimens. The mechanisms were explored via cell viability assay, flow cytometry, immunofluorescence, immunoblotting, co‐immunoprecipitation, and real‐time quantitative PCR in multiple murine and human CRC cell lines. Results Combining ATRi berzosertib and IR enhanced CD8+T cell infiltration and enhanced the efficacy of anti‐PD‐L1 therapy in mouse CRC models with different microsatellite statuses. The mechanistic study demonstrated that IR + ATRi could activate both the canonical cGAS‐STING‐pTBK1/pIRF3 axis by increasing cytosolic double‐stranded DNA levels and the non‐canonical STING signaling by attenuating SHP1‐mediated inhibition of the TRAF6‐STING‐p65 axis, via promoting SUMOylation of SHP1 at lysine 127. By boosting the STING signaling, IR + ATRi induced type I interferon‐related gene expression and strong innate immune activation and reinvigorated the cold tumor microenvironment, thus facilitating immunotherapy. Conclusions The combination of ATRi and IR could facilitate anti‐PD‐L1 therapy by promoting STING signaling in CRC models with different microsatellite statuses. The new combination strategy raised by our study is worth investigating in the management of CRC

Pharmacological inhibition of LSD1 suppresses growth of hepatocellular carcinoma by inducing GADD45B

Abstract Lysine‐specific histone demethylase 1 (LSD1) is an attractive target for malignancies therapy. Nevertheless, its role in hepatocellular carcinoma (HCC) progression and the potential of its inhibitor in HCC therapy remains unclear. Here, we show that LSD1 overexpression in human HCC tissues is associated with HCC progression and poor patient survival. ZY0511, a highly selective and potent inhibitor of LSD1, suppressed human HCC cell proliferation in vitro and tumor growth in cell‐derived and patient‐derived HCC xenograft models in vivo. Mechanistically, ZY0511 induced mRNA expression of growth arrest and DNA damage‐inducible gene 45beta (GADD45B) by inducing histone H3 at lysine 4 (H3K4) methylation at the promoter of GADD45B, a novel target gene of LSD1. In human HCC tissues, LSD1 level was correlated with a decreased level of GADD45B, which was associated with HCC progression and predicted poor patient survival. Moreover, co‐administration of ZY0511 and DTP3, which specifically enhanced the pro‐apoptotic effect of GADD45B, effectively inhibited HCC cell proliferation both in vitro and in vivo. Collectively, our study revealed the potential value of LSD1 as a promising target of HCC therapy. ZY0511 is a promising candidate for HCC therapy through upregulating GADD45B, thereby providing a novel combinatorial strategy for treating HCC

High-fat diet-induced upregulation of exosomal phosphatidylcholine contributes to insulin resistance

High-fat diet plays a role in development of insulin resistance. Here, the authors report a mechanism that underlies the development of diet induced insulin resistance through the activation of an aryl hydrocarbon receptor mediated signalling pathway in the liver by faecal exosomes derived from intestinal cells