DKK3 overexpression attenuates cardiac hypertrophy and fibrosis in an angiotensin-perfused animal model by regulating the ADAM17/ACE2 and GSK-3ß/ß-catenin pathways.

AIMS: Cardiac pressure and humoral factors induce cardiac hypertrophy and fibrosis, which are characterized by increased stiffness, reduced contractility and altered perfusion. Angiotensin II (AngII) is well known to promote this pathology. Angiotensin-converting enzyme (ACE) 2, which cleaves AngII and forms Ang-(1-7), exerts protective anti-hypertrophy and anti-fibrosis effects. A disintegrin and metalloproteinase 17 (ADAM17), a membrane-bound enzyme reported to cleave ACE2, may participate in the pathological process of AngII perfusion-induced heart damage. However, researchers have not clearly determined whether dickkopf-3 (DKK3) regulates the ADAM17/ACE2 pathway and, if so, whether DKK3-mediated regulation is related to the glycogen synthase kinase-3ß (GSK-3ß)/ß-catenin pathway. In this study, we explored whether DKK3 overexpression ameliorates the development of AngII-induced cardiac fibrosis and hypertrophy through the ADAM17/ACE2 and GSK-3ß/ß-catenin pathways. METHODS: Mice were injected with a DKK3-overexpressing adenovirus or vehicle and then infused with AngII or saline using subcutaneously implanted mini-pumps for four weeks. Hearts were stained with hematoxylin-eosin, Masson's trichrome and immunohistochemical markers for histology. Primary fibroblasts were treated with the adenovirus and AngII and then examined using western blotting, EdU (5-ethynyl-2'-deoxyuridine) assays and immunofluorescence. Additionally, siRNA silencing was performed to study the role of DKK3 and the involved pathways. RESULTS: AngII-induced cardiac hypertrophy and interstitial and perivascular fibrosis were less severe in DKK3-overexpressing mice than in control mice. Moreover, the expression levels of fibrotic genes, such as collagen I and III, and the hypertrophic genes atrial natriuretic peptide (ANP) and beta-myosin heavy chain (ß-MHC) were decreased. DKK3 overexpression also exerted a protective effect by inhibiting ADAM17 phosphorylation, thus increasing ACE2 expression and subsequently promoting AngII degradation. Furthermore, this process was mediated by the inhibition of GSK-3ß and ß-catenin and decreased translocation of ß-catenin to the nucleus. On the other hand, the DKK3 knockdown by siRNA achieved opposite results. CONCLUSION: DKK3 overexpression substantially alleviated AngII infusion-induced cardiac hypertrophy and fibrosis by regulating ADAM17/ACE2 pathway activity and inhibiting the GSK-3ß/ß-catenin pathway.

Causal associations between severe COVID-19 and diseases of seven organs: a proteome-wide mendelian randomization study.

The coronavirus disease 2019 (COVID-19) pandemic poses an enormous threat to public health worldwide. Many retrospective studies and case reports to date have shown associations between severe COVID-19 and diseases of multi-organs. However, the research on the causal mechanisms behind this phenomenon is neither extensive nor comprehensive. We conducted a proteome-wide Mendelian randomization (MR) study using summary statistics from a Genome-Wide Association Studies (GWAS) of severe COVID-19 and diseases related to seven organs: lung, spleen, liver, heart, kidney, testis, and thyroid, based on the European ancestry. The primary analytical method used is the radial inverse variance-weighted (radial IVW) method, supplemented with the inverse variance-weighted (IVW), weighted-median (WM), MR-Egger methods. Our findings have confirmed the association between severe COVID-19 and multiple organ-related diseases, such as Hypothyroidism, strict autoimmune (HTCBSA), Thyroid disorders (TD), and Graves' disease (GD). And we have also identified certain proteins that are associated with organ-related diseases, such as Superoxide Dismutase 2 (SOD2) and TEK Receptor Tyrosine Kinase (TEK), which are also considered potential drug targets. Phenotype scanning and sensitivity analyses were implemented to consolidate the results for Mendelian randomization. This study provides a compelling foundation for investigating COVID-19 caused diseases in future studies.

STAT3 Undergoes Acetylation-dependent Mitochondrial Translocation to Regulate Pyruvate Metabolism.

Cytoplasmic STAT3, after activation by growth factors, translocates to different subcellular compartments, including nuclei and mitochondria, where it carries out different biological functions. However, the precise mechanism by which STAT3 undergoes mitochondrial translocation and subsequently regulates the tricarboxylic acid (TCA) cycle-electron transport chain (ETC) remains poorly understood. Here, we clarify this process by visualizing STAT3 acetylation in starved cells after serum reintroduction or insulin stimulation. CBP-acetylated STAT3 undergoes mitochondrial translocation in response to serum introduction or insulin stimulation. In mitochondria, STAT3 associates with the pyruvate dehydrogenase complex E1 (PDC-E1) and subsequently accelerates the conversion of pyruvate to acetyl-CoA, elevates the mitochondrial membrane potential, and promotes ATP synthesis. SIRT5 deacetylates STAT3, thereby inhibiting its function in mitochondrial pyruvate metabolism. In the A549 lung cancer cell line, constitutively acetylated STAT3 localizes to mitochondria, where it maintains the mitochondrial membrane potential and ATP synthesis in an active state.