Function and mechanism of lysine crotonylation in health and disease.

Lysine crotonylation is a newly identified posttranslational modification that is different from the widely studied lysine acetylation in structure and function. In the last dozen years, great progress has been made in lysine crotonylation-related studies, and lysine crotonylation is involved in reproduction, development, and disease. In this review, we highlight the similarities and differences between lysine crotonylation and lysine acetylation. We also summarize the methods and tools for the detection and prediction of lysine crotonylation. At the same time, we outline the recent advances in understanding the mechanisms of enzymatic and metabolic regulation of lysine crotonylation, as well as the regulating factors that selectively recognize this modification. Particularly, we discussed how dynamic changes in crotonylation status maintain physiological health and result in the development of disease. This review not only points out the new functions of lysine crotonylation but also provides new insights and exciting opportunities for managing various diseases.

ß-Glucan Combined With PD-1/PD-L1 Checkpoint Blockade for Immunotherapy in Patients With Advanced Cancer.

Programmed death-1 (PD-1)/PD-ligand 1 (PD-L1) checkpoint blocking antibodies have been shown to be a powerful immune checkpoint blockade (ICB) therapy for patients with cancer. However, patients quickly develop resistance to immunotherapy. ß-glucan, an immune adjuvant, has been found to stimulate innate and adaptive immune responses. In this study, we assessed the use of whole glucan particle (WGP) ß-glucan in combination with PD-1/PD-L1-blocking antibodies to slow down the resistance to immunotherapy. Results from a tumor mouse model demonstrated that administration of WGP ß-glucan plus PD-1/PD-L1-blocking antibodies led to increased recruitment of immune-associated cells, improved regulation of the balance between T-cell activation and immune tolerance, and delayed tumor progression. This combination therapy was also found to improve progression-free survival in patients with advanced cancer who had previously discontinued anti-PD-1/PD-L1 because of disease progression. These findings suggest that ß-glucan could be used as an immune adjuvant to reverse anti-PD-1/PD-L1 resistance by regulating the immune system.

[Corrigendum] MicroRNA­1929­3p participates in murine cytomegalovirus­induced hypertensive vascular remodeling through Ednra/NLRP3 inflammasome activation.

Following the publication of this article, the authors have realized that the images selected for the 'MCMV+miR­NC' and 'MCMV+miR­1929­3p' data panels (15 months), as featured in the lower of the two rows of data shown in Fig. 4A on p. 726, were derived from the same experimental group. The authors re­examined their original data, and discovered that an error had inadvertently been made on account of the similar file names of the two images. The corrected version of Fig. 4, featuring the correct data for the 'MCMV+miR­NC' experiment, is shown on the next page. The authors regret that this error was not picked up upon before the paper was sent to press, and thank the Editor of International Journal of Molecular Medicine for allowing them the opportunity to publish a corrigendum. Note that the error did not affect either the results or the conclusions reported in the study, and all the authors agree to this corrigendum. Furthermore, the authors regret any inconvenience caused to the readership. [the original article was published in International Journal of Molecular Medicine 47: 719-731, 2021; DOI: 10.3892/ijmm.2020.4829].

Exposure to hypergravity during zebrafish development alters cartilage material properties and strain distribution.

AIMS: Vertebrates have adapted to life on Earth and its constant gravitational field, which exerts load on the body and influences the structure and function of tissues. While the effects of microgravity on muscle and bone homeostasis are well described, with sarcopenia and osteoporosis observed in astronauts returning from space, the effects of shorter exposures to increased gravitational fields are less well characterized. We aimed to test how hypergravity affects early cartilage and skeletal development in a zebrafish model. METHODS: We exposed zebrafish to 3 g and 6 g hypergravity from three to five days post-fertilization, when key events in jaw cartilage morphogenesis occur. Following this exposure, we performed immunostaining along with a range of histological stains and transmission electron microscopy (TEM) to examine cartilage morphology and structure, atomic force microscopy (AFM) and nanoindentation experiments to investigate the cartilage material properties, and finite element modelling to map the pattern of strain and stress in the skeletal rudiments. RESULTS: We did not observe changes to larval growth, or morphology of cartilage or muscle. However, we observed altered mechanical properties of jaw cartilages, and in these regions we saw changes to chondrocyte morphology and extracellular matrix (ECM) composition. These areas also correspond to places where strain and stress distribution are predicted to be most different following hypergravity exposure. CONCLUSION: Our results suggest that altered mechanical loading, through hypergravity exposure, affects chondrocyte maturation and ECM components, ultimately leading to changes to cartilage structure and function. Cite this article: Bone Joint Res 2021;10(2):137-148.

MicroRNA­1929­3p participates in murine cytomegalovirus­induced hypertensive vascular remodeling through Ednra/NLRP3 inflammasome activation.

MicroRNAs (miRNAs) play an important role in the development of vascular remodeling in essential hypertension (EH) by mediating the effects of human cytomegalovirus (HCMV) on the vascular system. Therefore, the aim of the present study was to investigate the effects of murine cytomegalovirus (MCMV) infection on blood pressure and vascular function in mice, in order to elucidate the role of miR­1929­3p in this process. For model development, 7­month­old C57BL/6J mice were infected with the Smith strain of MCMV, and MCMV DNA, IgG and IgM were detected. Subsequently, blood pressure was measured via the carotid artery, and the morphological changes of the aorta were evaluated by hematoxylin and eosin and Masson's trichrome staining. miR­1929­3p transfection was performed using an adeno­associated virus packaged vector and the changes in vascular structure were then observed. The levels of nitric oxide (NO) and endothelial NO synthase were also assessed with colorimetry. Vascular remodeling and expression of NLRP3 inflammasome pathway­related proteins were detected by immunohistochemistry and western blotting. Endothelin­1 (ET­1), interleukin (IL)­1ß and IL­18 were assayed by ELISA. The results revealed that MCMV infection increased the blood pressure, promoted vascular remodeling, caused endothelial cell injury, and downregulated miR­1929­3p. However, these effects were alleviated by miR­1929­3p overexpression, which downregulated endothelin A receptor (Ednra) and NLRP3 inflammasome, as well as endothelial injury­ and vascular remodeling­related genes. Taken together, the findings of the present study indicated that overexpression of miR­1929­3p may improve MCMV­induced vascular remodeling, possibly via the deactivation of the NLRP3 inflammasome by ET­1/Ednra.

Promotion of SIRT1 protein degradation and lower SIRT1 gene expression via reactive oxygen species is involved in Sb-induced apoptosis in BEAS-2b cells.

Antimony (Sb) has been reported to lead to pulmonary damage, but the underlying mechanism remains unclear. Accumulating evidence indicates that silent mating type information regulation 2 homolog 1 (SIRT1), an NAD+-dependent deacetylase, mediates stimuli-induced cellular apoptosis. Here, we investigated whether SIRT1 plays a role in Sb-triggered apoptosis in human bronchial epithelial cells (BEAS-2b). First, we showed that Sb initiated apoptosis. Furthermore, the expression of SIRT1 was markedly downregulated by Sb treatment, while overexpression of SIRT1 through resveratrol treatment or transfection with SIRT1-Flag plasmid attenuated the Sb-induced apoptosis. Accelerated degradation of SIRT1 protein and lower SIRT1 gene expression contributed to low expression of SIRT1. In addition, Sb activated the ERK and JNK pathways; however, inhibition of ERK rather than JNK rescued SIRT1 suppression. Subsequent analyses demonstrated that antioxidant N-acetylcysteine (NAC) attenuated SIRT1 repression, increased SIRT1 mRNA levels and decreased SIRT1 protein degradation in Sb-treated cells. In addition, NAC also inhibited JNK and ERK activation by Sb exposure. These data suggest that reactive oxygen species-dependent SIRT1 suppression mediates Sb-stimulated cell apoptosis in BEAS-2b cells via lower SIRT1 gene expression and protein stability.