Irisin enhances longevity by boosting SIRT1, AMPK, autophagy and telomerase

ELMO1 ameliorates intestinal epithelial cellular senescence via SIRT1/p65 signaling in inflammatory bowel disease-related fibrosis

Background

Intestinal fibrosis is a common complication in inflammatory bowel disease (IBD), which still lacks of reliable markers and therapeutic options. Cellular senescence has been considered an important mechanism of intestinal fibrosis, but the underlying molecular link remains elusive.

Methods

Tissues were stained using α-smooth muscle actin (α-SMA), fibronectin, and collagen I as markers of myofibroblastic differentiation. Cellular senescence was confirmed through Lamin B1 staining, senescence-associated β-galactosidase staining, and the expression of senescence-associated secretory phenotype (SASP) factors. We explored the relationship between senescence of intestinal epithelial cells (IECs) and intestinal fibrosis, as well as the molecular mechanism underlying this interaction. The effects of irisin on cellular senescence and fibrosis were determined.

Results

Here, we identify engulfment and cell motility protein 1 (ELMO1) as a novel biomarker for intestinal cellular senescence and fibrosis. In fibrostrictured tissues from patients and murine models with IBD, significantly high levels of cellular senescence score and factors were noted, which positively correlated with the fibrotic regulator fibronectin. Senescent IECs, not fibroblast itself, released SASP factors to regulate fibroblast activation. Prolonging exposure to severe and persistent injurious stimuli decreased ELMO1 expression, which dampened SIRT1 deacetylase activity, enhanced NF-κB (p65) acetylation, and thereby accelerated cellular senescence. Deletion of ELMO1 led to senescent IECs accumulation and triggered premature fibrosis in murine colitis. Furthermore, irisin, inhibiting the degradation of ELMO1, could downregulate p65 acetylation, reduce IECs senescence, and prevent incipient intestinal fibrosis in murine colitis models.

Conclusions

This study reveals ELMO1 downregulation is an early symbol of intestinal senescence and fibrosis, and the altered ELMO1-SIRT1-p65 pathway plays an important role in intestinal cellular senescence and IBD-related fibrosis.

Irisin attenuates ventilator-induced diaphragmatic dysfunction by inhibiting endoplasmic reticulum stress through activation of AMPK

Mechanical ventilation (MV) is an essential life-saving technique, but prolonged MV can cause significant diaphragmatic dysfunction due to atrophy and decreased contractility of the diaphragm fibres, called ventilator-induced diaphragmatic dysfunction (VIDD). It is not clear about the mechanism of occurrence and prevention measures of VIDD. Irisin is a newly discovered muscle factor that regulates energy metabolism. Studies have shown that irisin can exhibit protective effects by downregulating endoplasmic reticulum (ER) stress in a variety of diseases; whether irisin plays a protective role in VIDD has not been reported. Sprague-Dawley rats were mechanically ventilated to construct a VIDD model, and intervention was performed by intravenous administration of irisin. Diaphragm contractility, degree of atrophy, cross-sectional areas (CSAs), ER stress markers, AMPK protein expression, oxidative stress indicators and apoptotic cell levels were measured at the end of the experiment.Our findings showed that as the duration of ventilation increased, the more severe the VIDD was, the degree of ER stress increased, and the expression of irisin decreased.ER stress may be one of the causes of VIDD. Intervention with irisin ameliorated VIDD by reducing the degree of ER stress, attenuating oxidative stress, and decreasing the apoptotic index. MV decreases the expression of phosphorylated AMPK in the diaphragm, whereas the use of irisin increases the expression of phosphorylated AMPK. Irisin may exert its protective effect by activating the phosphorylated AMPK pathway.

Irisin: A Potentially Fresh Insight into the Molecular Mechanisms Underlying Vascular Aging

Aging is a natural process that affects all living organisms, including humans. Aging is a complex process that involves the gradual deterioration of various biological processes and systems, including the cardiovascular system. Vascular aging refers to age-related changes in blood vessels. These changes can increase the risk of developing cardiovascular diseases, such as hypertension, atherosclerosis, and stroke. Recently, an exercise-induced muscle factor, irisin, was found to directly improve metabolism and regulate the balance of glucolipid metabolism, thereby counteracting obesity and insulin resistance. Based on a growing body of evidence, irisin modulates vascular aging. Adenosine monophosphate-activated protein kinase (AMPK) serves as a pivotal cellular energy sensor and metabolic modulator, acting as a central signaling cascade to coordinate various cellular processes necessary for maintaining vascular homeostasis. The vascular regulatory effects of irisin are closely intertwined with its interaction with the AMPK pathway. In conclusion, understanding the molecular processes used by irisin to regulate changes in vascular diseases caused by aging may inspire the development of techniques that promote healthy vascular aging. This review sought to describe the impact of irisin on the molecular mechanisms of vascular aging, including inflammation, oxidative stress, and epigenetics, from the perspective of endothelial cell function and vascular macroregulation, and summarize the multiple signaling pathways used by irisin to regulate vascular aging.

Targeting SIRT1 synergistically improves the antitumor effect of JQ-1 in hepatocellular carcinoma

Bromodomain and extraterminal domain protein inhibitors have shown therapeutic promise in hepatocellular carcinoma. However, resistance to bromodomain and extraterminal domain protein inhibitors has emerged in preclinical trials, presenting an immense clinical challenge, and the mechanisms are unclear. In this study, we found that overexpression of SIRT1 induced by JQ-1, a bromodomain and extraterminal domain protein inhibitor, may confer resistance to JQ-1 in hepatocellular carcinoma. SIRT1 protein expression was higher in hepatocellular carcinoma tissues than in normal tissues, and this phenotype was correlated with a poor prognosis. Cotreatment with JQ-1 and the SIRT1 inhibitor EX527 synergistically suppressed proliferation and blocked cell cycle progression in hepatocellular carcinoma cells. Combined administration of JQ-1 and EX527 successfully reduced the tumor burden in vivo. In addition, JQ-1 mediated AMPK/p-AMPK axis activation to upregulate SIRT1 protein expression and enhanced autophagy to inhibit cell apoptosis. Activation of AMPK could alleviate the antitumor effect of the combination of JQ-1 and EX527 on hepatocellular carcinoma cells. Furthermore, inhibition of SIRT1 further enhanced the antitumor effect of JQ-1 by blocking protective autophagy in hepatocellular carcinoma. Our study proposes a novel and efficacious therapeutic strategy of a BET inhibitor combined with a SIRT1 inhibitor for hepatocellular carcinoma.

Irisin-loaded electrospun core-shell nanofibers as calvarial periosteum accelerate vascularized bone regeneration by activating the mitochondrial SIRT3 pathway

The scarcity of native periosteum poses a significant clinical barrier in the repair of critical-sized bone defects. The challenge of enhancing regenerative potential in bone healing is further compounded by oxidative stress at the fracture site. However, the introduction of artificial periosteum has demonstrated its ability to promote bone regeneration through the provision of appropriate mechanical support and controlled release of pro-osteogenic factors. In this study, a poly (l-lactic acid) (PLLA)/hyaluronic acid (HA)-based nanofibrous membrane was fabricated using the coaxial electrospinning technique. The incorporation of irisin into the core-shell structure of PLLA/HA nanofibers (PLLA/HA@Irisin) achieved its sustained release. In vitro experiments demonstrated that the PLLA/HA@Irisin membranes exhibited favorable biocompatibility. The osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs) was improved by PLLA/HA@Irisin, as evidenced by a significant increase in alkaline phosphatase activity and matrix mineralization. Mechanistically, PLLA/HA@Irisin significantly enhanced the mitochondrial function of BMMSCs via the activation of the sirtuin 3 antioxidant pathway. To assess the therapeutic effectiveness, PLLA/HA@Irisin membranes were implanted in situ into critical-sized calvarial defects in rats. The results at 4 and 8 weeks post-surgery indicated that the implantation of PLLA/HA@Irisin exhibited superior efficacy in promoting vascularized bone formation, as demonstrated by the enhancement of bone matrix synthesis and the development of new blood vessels. The results of our study indicate that the electrospun PLLA/HA@Irisin nanofibers possess characteristics of a biomimetic periosteum, showing potential for effectively treating critical-sized bone defects by improving the mitochondrial function and maintaining redox homeostasis of BMMSCs.