Downregulation of FKBP5 Promotes Atrial Arrhythmogenesis

A High-Protein Diet Promotes Atrial Arrhythmogenesis via Absent-in-Melanoma 2 Inflammasome

High-protein diets (HPDs) offer health benefits, such as weight management and improved metabolic profiles. The effects of HPD on cardiac arrhythmogenesis remain unclear. Atrial fibrillation (AF), the most common arrhythmia, is associated with inflammasome activation. The role of the Absent-in-Melanoma 2 (AIM2) inflammasome in AF pathogenesis remains unexplored. In this study, we discovered that HPD increased susceptibility to AF. To demonstrate the involvement of AIM2 signaling in the pathogenesis of HPD-induced AF, wildtype (WT) and Aim2-/- mice were fed normal-chow (NC) and HPD, respectively. Four weeks later, inflammasome activity was upregulated in the atria of WT-HPD mice, but not in the Aim2-/--HPD mice. The increased AF vulnerability in WT-HPD mice was associated with abnormal sarcoplasmic reticulum (SR) Ca2+-release events in atrial myocytes. HPD increased the cytoplasmic double-strand (ds) DNA level, causing AIM2 activation. Genetic inhibition of AIM2 in Aim2-/- mice reduced susceptibility to AF, cytoplasmic dsDNA level, mitochondrial ROS production, and abnormal SR Ca2+-release in atrial myocytes. These data suggest that HPD creates a substrate conducive to AF development by activating the AIM2-inflammasome, which is associated with mitochondrial oxidative stress along with proarrhythmic SR Ca2+-release. Our data imply that targeting the AIM2 inflammasome might constitute a novel anti-AF strategy in certain patient subpopulations.

MicroRNA hsa-miR-320a-3p and Its Targeted mRNA FKBP5 Were Differentially Expressed in Patients with HIV/TB Co-Infection

Among the PLWH (people living with HIV) population, the risk of developing active tuberculosis (TB) is increasing. Active TB also accelerates the deterioration of PLWH's immune function and is one of the leading causes of death in the PLWH population. So far, accurate diagnosis of active TB in the PLWH population remains challenging. Through data analysis of HIV/TB co-infection in the GEO database, the differentially expressed genes as well as their related microRNA (miRNA) were acquired and were further verified through clinical blood samples. Dual-luciferase assay was used to verify the mechanism of miRNA on mRNA. The enrichment of immune cells in database patient samples was analyzed by bioinformatics and finally verified by blood routine data. Our study found that FKBP5 (FK506 binding protein 5) was highly expressed in the HIV/TB co-infection group; hsa-miR-320a-3p was highly expressed in the HIV infection group but decreased in the HIV/TB co-infection group. Dual-luciferase assay results showed that hsa-miR-320a-3p mimics significantly reduced the relative luciferase activity of the WT-FKBP5 group; however, this phenomenon was not observed in the MUT-FKBP5 group. At the same time, as a key molecule of the immune-related pathway, FKBP5 is highly correlated with the amount of neutrophils, which provides a new suggestion for the treatment of the HIV/TB co-infection population. Our study found that hsa-miR-320a-3p can decrease FKBP5 expression, suggesting a potential regulatory role for FKBP5. The involvement of FKBP5 and its related molecule hsa-miR-320a-3p in HIV/TB co-infection proposes them as potential biomarkers for the diagnosis of active TB in the PLWH population.

Role of FKBP5 and its genetic mutations in stress-induced psychiatric disorders: an opportunity for drug discovery

Stress-induced mental health disorders are affecting many people around the world. However, effective drug therapy for curing psychiatric diseases does not occur sufficiently. Many neurotransmitters, hormones, and mechanisms are essential in regulating the body's stress response. One of the most critical components of the stress response system is the hypothalamus-pituitary-adrenal (HPA) axis. The FKBP prolyl isomerase 51 (FKBP51) protein is one of the main negative regulators of the HPA axis. FKBP51 negatively regulates the cortisol effects (the end product of the HPA axis) by inhibiting the interaction between glucocorticoid receptors (GRs) and cortisol, causing reduced transcription of downstream cortisol molecules. By regulating cortisol effects, the FKBP51 protein can indirectly regulate the sensitivity of the HPA axis to stressors. Previous studies have indicated the influence of FKBP5 gene mutations and epigenetic changes in different psychiatric diseases and drug responses and recommended the FKBP51 protein as a drug target and a biomarker for psychological disorders. In this review, we attempted to discuss the effects of the FKBP5 gene, its mutations on different psychiatric diseases, and drugs affecting the FKBP5 gene.