SWI/SNF complex subunit BAF60a represses hepatic ureagenesis through a crosstalk between YB-1 and PGC-1α

The circAno6/miR-296-3p/TLR4 signaling axis mediates the inflammatory response to induce the activation of hepatic stellate cells

BACKGROUND

Circular RNA (circRNA) is a novel functional non-coding RNA(ncRNA) that plays a role in the occurrence and development of multiple human liver diseases, including liver fibrosis (LF). LF is a reversible repair response after liver injury, and the activation of hepatic stellate cells (HSCs) is the core event. However, the regulatory mechanisms by which circRNAs induce the activation of HSCs in LF are still poorly understood. The circAno6/miR-296-3p/toll-like receptor 4 (TLR4) signaling axis that mediates the inflammatory response and causes the activation of HSCs was investigated in this study.

METHODS

First, a circAno6 overexpression plasmid and small interfering RNA were transfected into cells to determine whether circAno6 can affect the function of HSCs. Second, real-time quantitative polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), western blotting (WB) and immunofluorescence (IF) were used to detect the effects of circAno6 plasmid/siRNA transfection on HSC activation indices, inflammatory markers and the circAno6/miR-296-3p/TLR4 signaling axis. The subcellular position of circAno6 was then examined by nucleo-cytoplasmic separation and fluorescence in situ hybridization (FISH). Finally, a luciferase reporter gene assay was used to identify the relationship between circAno6 and miR-296-3p as well as the relationship between miR-296-3p and TLR4.

RESULTS

CircAno6 was considerably upregulated in HSCs and positively correlated with cell proliferation and alpha-smooth muscle actin (α-SMA), collagen I, NOD-likereceptorthermalproteindomainassociatedprotein 3 (NLRP3), interleukin-1β (IL-1β) and interleukin-18 (IL-18) expression. Overexpression of circAno6 increased the inflammatory response and induced HSC activation, whereas interference resulted in the opposite effects. FISH experiments revealed the localization of circAno6 in the cytoplasm. Then, a double luciferase reporter assay confirmed that miR-296-3p significantly inhibited luciferase activity in the circAno6-WT and TLR4-WT groups.

CONCLUSION

This study suggests that circAno6 and miR-296-3p/TLR4 may form a regulatory axis and regulate the inflammatory response, which in turn induces HSC activation. Targeting circAno6 may be a potential therapeutic strategy to treat LF.

A chromatin remodeling checkpoint of diet-induced macrophage activation in adipose tissue

The interplay between the environment and the immune cells is linked to metabolic homeostasis under physiologic and pathophysiologic conditions. Diabetes mellitus type 2 (T2D) is considered an immune-related inflammatory disorder, in which the adipose tissue macrophages (ATMs) are key players orchestrating metabolic chronic meta-inflammation and contributing to the pathogenesis of metabolic disease. However, the molecular regulators that integrate the environmental signals to control ATM activation and adipose inflammation during obesity and T2D remain unclear. Epigenetic mechanisms constitute important parameters in metabolic homeostasis, obesity and T2D via the integration of the environmental factors to the transcriptional regulation of gene programs. In a very recent study published in Diabetes by Kong et al., BAF60a has been identified as a key chromatin remodeling checkpoint factor that associates obesity-associated stress signals with meta-inflammation and systemic homeostasis. Furthermore, this work uncovers Atf3 as an important downstream effector in BAF60a-mediated chromatin remodeling and transcriptional reprogramming of macrophage activation in adipose tissue. The findings of this research may contribute to the development of new therapeutic approaches for obesity-induced metabolic inflammation and associated metabolic disorders.

MMP-12 siRNA improves the homeostasis of the small intestine and metabolic dysfunction in high-fat diet feeding-induced obese mice

The changes of small intestinal homeostasis have been recognized to contribute essentially to the obese development. However, the core small intestinal regulator which mediates over-nutrient impacts on the homeostasis of the small intestines remains elusive. Here, we identify the MMP-12 as such a responsive factor in mouse small intestines. Taking advantages of the nano delivery system, we demonstrate that small intestine-specific MMP-12 knockdown alleviates high-fat diet feeding-induced metabolic disorders and improves intestinal homeostasis in mice, including a significant decrease in lipid transportation, bile acid reabsorption, and inflammation. In parallel, the small intestinal integrity is recovered and the gut microbiota composition is reversed towards that under normal diet feeding. Mechanistically, MMP-12, differing from its traditional elastolytic function, acts as a transcriptional factor to activate Fabp4 transcription through epigenetic modification. In translational medicine, clinical applications of our nanosystem and therapeutic interventions targeting MMP-12 will benefit patients with obesity and associated diseases.

Self-assembled polymeric nanocarrier-mediated co-delivery of metformin and doxorubicin for melanoma therapy

Malignant melanoma is a life-threatening form of skin cancer with a low response rate to single-agent chemotherapy. Although combined therapies of metformin (MET) and doxorubicin (DOX) are effective in treating a variety of cancers, including breast cancer, their different physicochemical properties and administration routines reduce the effective co-accumulation of both drugs in tumors. Nanoparticles (NPs) have been demonstrated to potentially improve drug delivery efficiency in cancer therapy of, for example, liver and lung cancers. Hence, in this study, we prepared pH-sensitive, biocompatible, tumor-targeting NPs based on the conjugation of biomaterials, including sodium alginate, cholesterol, and folic acid (FCA). As expected, since cholesterol and folic acid are two essentials, but insufficient, substrates for melanoma growth, we observed that the FCA NPs specifically and highly effectively accumulated in xenograft melanoma tumors. Taking advantage of the FCA NP system, we successfully co-delivered a combination of MET and DOX into melanoma tumors to trigger pyroptosis, apoptosis, and necroptosis (PANoptosis) of the melanoma cells, thus blocking melanoma progression. Combined, the establishment of such an FCA NP system provides a promising vector for effective drug delivery into melanoma and increases the possibility and efficiency of drug combinations for cancer treatment.

CPS1: Looking at an ancient enzyme in a modern light

The mammalian urea cycle (UC) is responsible for siphoning catabolic waste nitrogen into urea for excretion. Disruptions of the functions of any of the enzymes or transporters lead to elevated ammonia and neurological injury. Carbamoyl phosphate synthetase 1 (CPS1) is the first and rate-limiting UC enzyme responsible for the direct incorporation of ammonia into UC intermediates. Symptoms in CPS1 deficiency are typically the most severe of all UC disorders, and current clinical management is insufficient to prevent the associated morbidities and high mortality. With recent advances in basic and translational studies of CPS1, appreciation for this enzyme's essential role in the UC has been broadened to include systemic metabolic regulation during homeostasis and disease. Here, we review recent advances in CPS1 biology and contextualize them around the role of CPS1 in health and disease.