New insight into molecular mechanisms of different polyphenols affecting Sirtuin 3 deacetylation activity.

Multiple phenolic substances have been shown to promote SIRT3 expression, however, few studies have focused on the effects of these phenolics on SIRT3 enzyme activity. This study constructed a variety of reaction systems to elucidate the mechanisms by which different polyphenols affect SIRT3 enzyme activity. The results showed that acP53317-320 was the most suitable substrate among the five acetylated peptide substrates (Kcat/Km = 74.85 ± 1.86 M-1•s-1). All the phenolic compounds involved in the experiment inhibited the enzymatic activity of SIRT3, and the lowest IC50 among them was quercetin (0.12 ± 0.01 mM) and the highest was piceatannol (1.29 ± 0.08 mM). Their inhibition types were mainly competitive and mixed. In addition, piceatannol was found to be a natural SIRT3 agonist by enzyme kinetic analysis and validation of deacetylation efficiency. This study will provide a useful reference for polyphenol modulation of SIRT3 dosage, as well as the development and application of polyphenol-based SIRT3 activators and agonists.

CLMP is a tumor suppressor that determines all-trans retinoic acid response in colorectal cancer.

CAR-like membrane protein (CLMP) is a tight junction-associated protein whose mutation is associated with congenital short bowel syndrome (CSBS), but its functions in colorectal cancer (CRC) remain unknown. Here, we demonstrate that CLMP is rarely mutated but significantly decreased in CRC patients, and its deficiency accelerates CRC tumorigenesis, growth, and resistance to all-trans retinoic acid (ATRA). Mechanistically, CLMP recruits ß-catenin to cell membrane, independent of cadherin proteins. CLMP-mediated ß-catenin translocation inactivates Wnt(Wingless and INT-1)/ß-catenin signaling, thereby suppressing CRC tumorigenesis and growth in ApcMin/+, azoxymethane/dextran sodium sulfate (AOM/DSS), and orthotopic CRC mouse models. As a direct target of Wnt/ß-catenin, cytochrome P450 hydroxylase A1 (CYP26A1)-an enzyme that degrades ATRA to a less bioactive retinoid-is upregulated by CLMP deficiency, resulting in ATRA-resistant CRC that can be reversed by administering CYP26A1 inhibitor. Collectively, our data identify the anti-CRC role of CLMP and suggest that CYP26A1 inhibitor enable to boost ATRA's therapeutic efficiency.

The potential role of ferroptosis in COVID-19-related cardiovascular injury.

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged as a global health threat in 2019. An important feature of the disease is that multiorgan symptoms of SARS-CoV-2 infection persist after recovery. Evidence indicates that people who recovered from COVID-19, even those under the age of 65 years without cardiovascular risk factors such as smoking, obesity, hypertension, and diabetes, had a significantly increased risk of cardiovascular disease for up to one year after diagnosis. Therefore, it is important to closely monitor individuals who have recovered from COVID-19 for potential cardiovascular damage that may manifest at a later stage. Ferroptosis is an iron-dependent form of non-apoptotic cell death characterized by the production of reactive oxygen species (ROS) and increased lipid peroxide levels. Several studies have demonstrated that ferroptosis plays an important role in cancer, ischemia/reperfusion injury (I/RI), and other cardiovascular diseases. Altered iron metabolism, upregulation of reactive oxygen species, and glutathione peroxidase 4 inactivation are striking features of COVID-19-related cardiovascular injury. SARS-CoV-2 can cause cardiovascular ferroptosis, leading to cardiovascular damage. Understanding the mechanism of ferroptosis in COVID-19-related cardiovascular injuries will contribute to the development of treatment regimens for preventing or reducing COVID-19-related cardiovascular complications. In this article, we go over the pathophysiological underpinnings of SARS-CoV-2-induced acute and chronic cardiovascular injury, the function of ferroptosis, and prospective treatment approaches.

Functional deficiency of succinate dehydrogenase promotes tumorigenesis and development of clear cell renal cell carcinoma through weakening of ferroptosis.

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal carcinomas, with high mortality and poor prognoses worldwide. Succinate dehydrogenase (SDH) consists of four nuclear-encoded subunits and it is the only complex involved in both the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS). Previous studies have shown decreased SDH activity in ccRCC. However, the role and underlying molecular mechanisms of SDH in ccRCC initiation and development remain unclear. In the present study, pan-cancer analysis of SDH gene expression was analyzed and the relationship between SDH gene expression and clinicopathological parameters was assessed using different databases. cBioPortal, UACLAN, and Tumor Immune Estimation Resource (TIMER) were subsequently utilized to analyze genetic alterations, methylation, and immune cell infiltration of SDH genes in ccRCC patients. We found SDHs were significantly downregulated in ccRCC tissues and correlated with ccRCC progression. Increased methylation and high SDH promoter mutation rates may be the cause of reduced expression of SDHs in ccRCC. Moreover, the interaction network showed that SDH genes were correlated with ferroptosis-related genes. We further demonstrated that SDH inhibition dampened oxidative phosphorylation, reduced ferroptotic events, and restored ferroptotic cell death, characterized by eliminated mitochondrial ROS levels, decreased cellular ROS and diminished peroxide accumulation. Collectively, this study provides new insights into the regulatory role of SDH in the carcinogenesis and progression of ccRCC, introducing a potential target for advanced antitumor therapy through ferroptosis.

miR-34a is a microRNA safeguard for Citrobacter-induced inflammatory colon oncogenesis.

Inflammation often induces regeneration to repair the tissue damage. However, chronic inflammation can transform temporary hyperplasia into a fertile ground for tumorigenesis. Here, we demonstrate that the microRNA miR-34a acts as a central safeguard to protect the inflammatory stem cell niche and reparative regeneration. Although playing little role in regular homeostasis, miR-34a deficiency leads to colon tumorigenesis after Citrobacter rodentium infection. miR-34a targets both immune and epithelial cells to restrain inflammation-induced stem cell proliferation. miR-34a targets Interleukin six receptor (IL-6R) and Interleukin 23 receptor (IL-23R) to suppress T helper 17 (Th17) cell differentiation and expansion, targets chemokine CCL22 to hinder Th17 cell recruitment to the colon epithelium, and targets an orphan receptor Interleukin 17 receptor D (IL-17RD) to inhibit IL-17-induced stem cell proliferation. Our study highlights the importance of microRNAs in protecting the stem cell niche during inflammation despite their lack of function in regular tissue homeostasis.