Regulation of nucleocytoplasmic transport by ADP-ribosylation: the emerging role of karyopherin-β1 mono-ADP-ribosylation by ARTD15

SMYD3-PARP16 axis accelerates unfolded protein response and mediates neointima formation

Neointimal hyperplasia after vascular injury is a representative complication of restenosis. Endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) is involved in the pathogenesis of vascular intimal hyperplasia. PARP16, a member of the poly(ADP-ribose) polymerases family, is correlated with the nuclear envelope and the ER. Here, we found that PERK and IRE1α are ADP-ribosylated by PARP16, and this might promote proliferation and migration of smooth muscle cells (SMCs) during the platelet-derived growth factor (PDGF)-BB stimulating. Using chromatin immunoprecipitation coupled with deep sequencing (ChIP-seq) analysis, PARP16 was identified as a novel target gene for histone H3 lysine 4 (H3K4) methyltransferase SMYD3, and SMYD3 could bind to the promoter of Parp16 and increased H3K4me3 level to activate its host gene's transcription, which causes UPR activation and SMC proliferation. Moreover, knockdown either of PARP16 or SMYD3 impeded the ER stress and SMC proliferation. On the contrary, overexpression of PARP16 induced ER stress and SMC proliferation and migration. In vivo depletion of PARP16 attenuated injury-induced neointimal hyperplasia by mediating UPR activation and neointimal SMC proliferation. This study identified SMYD3-PARP16 is a novel signal axis in regulating UPR and neointimal hyperplasia, and targeting this axis has implications in preventing neointimal hyperplasia related diseases.

KPNB1-mediated nuclear translocation of PD-L1 promotes non-small cell lung cancer cell proliferation via the Gas6/MerTK signaling pathway

In addition to the role of programmed cell death ligand 1 (PD-L1) in facilitating tumour cells escape from immune surveillance, it is considered as a crucial effector in transducing intrinsic signals to promote tumour development. Our previous study has pointed out that PD-L1 promotes non-small cell lung cancer (NSCLC) cell proliferation, but the mechanism remains elusive. Here we first demonstrated that PD-L1 expression levels were positively correlated with p-MerTK levels in patient samples and NSCLC cell lines. In addition, PD-L1 knockdown led to the reduced phosphorylation level of MerTK in vitro. We next showed that PD-L1 regulated NSCLC cell proliferation via Gas6/MerTK signaling pathway in vitro and in vivo. To investigate the underlying mechanism, we unexpectedly found that PD-L1 translocated into the nucleus of cancer cells which was facilitated through the binding of Karyopherin β1 (KPNB1). Nuclear PD-L1 (nPD-L1), coupled with transcription factor Sp1, regulated the synthesis of Gas6 mRNA and promoted Gas6 secretion to activate MerTK signaling pathway. Taken together, our results shed light on the novel role of nPD-L1 in NSCLC cell proliferation and reveal a new molecular mechanism underlying nPD-L1-mediated Gas6/MerTK signaling activation. All above findings provide the possible combinational implications for PD-L1 targeted immunotherapy in the clinic.

Analysis of Mono-ADP-Ribosylation Levels in Human Colorectal Cancer

BACKGROUND

Colorectal cancer remains a major public health problem with high morbidity and mortality rates. In the search for the mechanisms of colorectal cancer occurrence and development, increasing attention has been focused on epigenetics. The overall level of Mono-ADP-ribosylation, an epigenetic, has not been investigated now. The aim of our study was to analysis of the overall level of mono-ADP-ribosylation in colorectal cancer.

METHODS

Immunohistochemistry was used to investigate the level of mono-ADP-ribosylation in colorectal cancer and normal colorectal adjacent tissue from 64 CRC patients. The data of patient demographic, clinical and pathological characteristics were acquired and analyzed.

RESULTS

Mono-ADP-ribosylation was present in both colorectal adenocarcinoma and normal colorectal tissue. The overall level of mono-ADP-ribosylation in colorectal cancer was significantly higher than that in normal colorectal adjacent tissue. In the nucleus, the majority of samples in the high-level group were colorectal adenocarcinoma (55/64), but the opposite was true for normal colorectal tissues (7/32). In particular, increases in the level of mono-ADP-ribosylation in the cytoplasm of colorectal cancer cells was associated with a greater invasion depth of the tumor.

CONCLUSION

The increased level of mono-ADP-ribosylation in colorectal cancer enhances tumor invasion, which suggests that mono-ADP-ribosylation is involved in the development of colorectal cancer and may become a new direction to solve the problem of colorectal cancer.