Aldosterone alters the chromatin structure of the murine endothelin-1 gene

Aldosterone: Renal Action and Physiological Effects

Aldosterone exerts profound effects on renal and cardiovascular physiology. In the kidney, aldosterone acts to preserve electrolyte and acid-base balance in response to changes in dietary sodium (Na+ ) or potassium (K+ ) intake. These physiological actions, principally through activation of mineralocorticoid receptors (MRs), have important effects particularly in patients with renal and cardiovascular disease as demonstrated by multiple clinical trials. Multiple factors, be they genetic, humoral, dietary, or otherwise, can play a role in influencing the rate of aldosterone synthesis and secretion from the adrenal cortex. Normally, aldosterone secretion and action respond to dietary Na+ intake. In the kidney, the distal nephron and collecting duct are the main targets of aldosterone and MR action, which stimulates Na+ absorption in part via the epithelial Na+ channel (ENaC), the principal channel responsible for the fine-tuning of Na+ balance. Our understanding of the regulatory factors that allow aldosterone, via multiple signaling pathways, to function properly clearly implicates this hormone as central to many pathophysiological effects that become dysfunctional in disease states. Numerous pathologies that affect blood pressure (BP), electrolyte balance, and overall cardiovascular health are due to abnormal secretion of aldosterone, mutations in MR, ENaC, or effectors and modulators of their action. Study of the mechanisms of these pathologies has allowed researchers and clinicians to create novel dietary and pharmacological targets to improve human health. This article covers the regulation of aldosterone synthesis and secretion, receptors, effector molecules, and signaling pathways that modulate its action in the kidney. We also consider the role of aldosterone in disease and the benefit of mineralocorticoid antagonists. © 2023 American Physiological Society. Compr Physiol 13:4409-4491, 2023.

Circadian clocks of the kidney: function, mechanism, and regulation

An intrinsic cellular circadian clock is located in nearly every cell of the body. The peripheral circadian clocks within the cells of the kidney contribute to the regulation of a variety of renal processes. In this review, we summarize what is currently known regarding the function, mechanism, and regulation of kidney clocks. Additionally, the effect of extrarenal physiological processes, such as endocrine and neuronal signals, on kidney function is also reviewed. Circadian rhythms in renal function are an integral part of kidney physiology, underscoring the importance of considering time of day as a key biological variable. The field of circadian renal physiology is of tremendous relevance, but with limited physiological and mechanistic information on the kidney clocks this is an area in need of extensive investigation.

Berberine ameliorates lipopolysaccharide‑induced inflammatory responses in mouse inner medullary collecting duct‑3 cells by downregulation of NF‑κB pathway

The major role of inner medullary collecting duct (IMCD) cells is to maintain water and sodium homeostasis. In addition to the major role, it also participates in the protection of renal and systemic inflammation. Although IMCD cells could take part in renal and systemic inflammation, investigations on renal inflammation in IMCD cells have rarely been reported. Although berberine (BBR) has been reported to show diverse pharmacological effects, its anti-inflammatory and protective effects on IMCD cells have not been studied. Therefore, in the present study, we examined the anti-inflammatory and protective effects of BBR in mouse IMCD-3 (mIMCD-3) cells against lipopolysaccharide (LPS). An MTT assay was carried out to investigate the toxicity of BBR on mIMCD-3 cells. Reverse transcription quantitative-PCR and western blotting were performed to analysis pro-inflammatory molecules and cytokines. Mechanisms of BBR were examined by western blotting and immunocytochemistry. According to previous studies, pro-inflammatory molecules, such as inducible nitric oxide synthase and cyclooxygenase-2, and pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6 and tumor necrosis factor-α are increased in LPS-exposed mIMCD-3 cells. However, the production of these pro-inflammatory molecules is significantly inhibited by treatment with BBR. In addition, BBR inhibited translocation of nuclear factor (NF)-κB p65 from the cytosol to the nucleus, and degradation of inhibitory κ-Bα in LPS-exposed mIMCD-3 cells. In conclusion, BBR could inhibit renal inflammatory responses via inhibition of NF-κB signaling and ultimately contribute to amelioration of renal injury during systemic inflammation.

Characterization and Gene Expression Analysis of Serum-Derived Extracellular Vesicles in Primary Aldosteronism

Patients affected by primary aldosteronism (PA) display an increased risk of cardiovascular events compared with essential hypertension (EH). Endothelial dysfunction favors initiation and progression of atherosclerosis and circulating extracellular vesicles (EVs), reflecting endothelial cell activity, could represent one of the mediators of endothelial dysfunction in these patients. The aim of this study was to characterize circulating EVs from patients diagnosed with PA and to explore their functional significance. Serum EVs were isolated from 12 patients with PA and 12 with EH, matched by sex, age, and blood pressure, and compared with 8 normotensive controls. At nanoparticle tracking analysis, EVs concentration was 2.2× higher in patients with PA ( P =0.033) compared with EH and a significant correlation between EV number and serum aldosterone and potassium levels was identified. Fluorescence-activated cell sorting analysis demonstrated that patients with PA presented a higher absolute number of endothelial-derived EVs compared with both patients with EH and normotensive controls. Through EV mRNA profiling, 15 up-regulated and 4 down-regulated genes in patients with PA compared with EH were identified; moreover, EDN1 was expressed only in patients with PA. Microarray platform was validated by quantative real-time polymerase chain reaction on 4 genes ( CASP1 , EDN1 , F2R , and HMOX1 ) involved in apoptosis, inflammation, and endothelial dysfunction. After unilateral adrenalectomy, EVs number and expression of CASP1 and EDN1 significantly decreased in patients with PA ( P <0.05). Additionally, the incubation with PA-derived EVs reduced angiogenesis and induced apoptosis in vitro. Circulating EVs might not only represent a marker of endothelial dysfunction but also contribute themselves to vascular dysfunction in patients with PA.