Biology subjects

Armando, I.

Publications and source records attributed to Armando, I..

3 recordsLinked to original sources

bioRxiv2026

The human GRK4Gamma griego minusculo 65L variant causes salt-sensitive hypertension by increasing renal SLC4A5 expression through the HDAC1 pathway

Salt-sensitive hypertension, a condition in which the blood pressure (BP) increases with an increase in salt intake, is influenced by behavioral, genetic, and environmental factors. Salt sensitivity is associated with variants of the G protein-coupled receptor kinase 4{gamma} (GRK4{gamma}) and the renal sodium bicarbonate cotransporter 2 (NBCe2), encoded by the solute carrier family 4 member 5 (SLC4A5). The R>65L variant (rs2960306) of human GRK4 (hGRK4{gamma} 65L) contributes to salt sensitivity through a signaling pathway and gene-gene interaction with SLC4A5. Global expression of GRK4{gamma} 65L in transgenic mice results in salt-sensitive hypertension, due in part to an increase in endogenous GRK4 and angiotensin type 1 receptor (AT1R) expression. Grk4 knockout (Grk4-/-) mice have decreased blood pressure and are salt-resistant. The expression of hGRK4{gamma} 65L only in the kidney of Grk4-/- mice increases BP in response to a high salt diet. The renal expression of SLC4A5 is increased in hGRK4{gamma} 65L transgenic mice, relative to mice expressing wild-type (WT) human GRK4 (hGRK4 65L), without endogenous mGrk4. Human renal proximal tubule cells (hRPTCs) endogenously expressing GRK4 WT and SLC4A5 WT, SLC4A5 variants, GRK4 65L, and both GRK4 65L and SLC4A5 variants were studied. SLC4A5 expression is increased in hRPTCs expressing GRK4 65L and in cells expressing both GRK4 65L and SLC4A5 variants compared with GRK4 WT and SLC4A5 WT. Luminal and basolateral sodium transport in hRPTCs is increased in the presence of both hGRK4 65L and SLC4A5 variants. GRK4 interacts with nuclear histone deacetylases (HDACs). Mice expressing hGRK4 65L only in the kidney have decreased expression but increased phosphorylation of HDAC1. HDAC1 expression is decreased and HDAC1 but not HDAC2 phosphorylation is increased in hRPTCs expressing both hGRK4 65L and SLC4A5 variants. The presence of hGRK4{gamma} 65L decreased HDAC1 expression but increased AT1R expression in the kidneys of mice on high salt diet. Our results show that GRK4{gamma} 65L causes salt-sensitive hypertension by increasing renal SLC4A5 and AT1R expressions by inhibiting the HDAC1 pathway.

molecular biology↗

bioRxiv2025

Role of NLRP3 activation in salt sensitive blood pressure regulation, effect of ND-13

Background and ObjectivesHigh salt intake is a major contributor to the development and exacerbation of hypertension, partly by inducing an inflammatory response through immune cell dysfunction. Inflammasomes, key components of the innate immune response, may influence blood pressure regulation. The renal DJ-1 protein is known for its antioxidant and anti-inflammatory properties. To explore novel pharmacological applications of renal DJ-1 pathway, we developed ND-13, a peptide consisting of 13 highly conserved amino acids derived from the DJ-1 sequence. In this study, we investigated the effects of ND-13 and MCC950, a specific NLRP3 inflammasome inhibitor, on blood pressure regulation in C57BL/6J mice on a high-salt diet. MethodsC57BL/6J mice were fed a high-salt diet (HS) for one week and then treated with ND-13 or MCC950, an NLRP3 inflammasome inhibitor. Subsequently, gene expression by qPCR, staining of immune cells, Sirius Red and Periodic Acid-Schiff (PAS) staining were determined in the mice kidneys, as well as the inflammasome activity in peritoneal cells. ResultsOne week of HS resulted increased in blood pressure, that was prevented by both ND-13 and MCC950 treatments. These treatments also prevented the increase in proteinuria that was accompanied by tubular protein deposits. Renal expression of inflammatory genes, immune cell infiltration, and renal collagen deposition were not observed in the HS group. Peritoneal macrophages isolated from HS treated mice exhibited enhanced IL-1{beta} release upon LPS+ATP stimulation, suggesting activation of the NLRP3 inflammasome. Treatment with ND-13 and MCC950 normalized this activity. Furthermore, ND-13 reduced IL-1{beta} mRNA expression in peritoneal macrophages. ConclusionsOur findings highlight the critical role of the NLRP3 inflammasome in salt-sensitive blood pressure regulation and suggest that ND-13 may serve as a potential therapeutic agent for preventing hypertension and associated inflammatory alterations induced by a high salt intake.

physiology↗

bioRxiv2024

DOPAMINE D4 RECEPTOR DOWN-REGULATES RENAL SODIUM CHLORIDE COTRANSPORTER VIA UBIQUITINATION-ASSOCIATED LYSOSOME DEGRADATION

BackgroundThe thiazide-sensitive sodium chloride cotransporter (NCC) is the major apical sodium transporter located in the mammalian renal distal convoluted tubule (DCT). The amount of sodium reabsorbed in the DCT through NCC plays an important role in the regulation of extracellular fluid volume and blood pressure. Dopamine and its receptors constitute a renal antihypertensive system in mammals. The disruption of Drd4 in mice causes kidney-related hypertension. However, the pathogenesis of D4R-deficiency associated hypertension is not well documented. MethodWe assessed the effects of D4R on NCC protein abundances and activities of DCT in mice with renal or global Drd4-deficiencies and expressing human D4.7 variant and in cultured mouse DCT cells, and explored the molecular mechanism. ResultsNCC inhibitor hydrochlorothiazide enhanced the natriuresis in Drd4-/- mice. Renal NCC protein was greater while ubiquitination of NCC was less in Drd4-/- than Drd4+/+ mice. Silencing of D4R in cultured mouse DCT cells increased NCC protein but decreased NCC ubiquitination. D4R agonist had opposite effects that were blocked by the antagonist. In mouse kidneys and DCT cells D4R and NCC colocalized and co-immunoprecipitated. Moreover, D4R-agonist promoted the binding between the two proteins demonstrated by fluorescence resonance energy transfer. D4R agonism internalized NCC, decreased NCC in the plasma membrane, increased NCC in lysosomes and reduced NCC-dependent-intracellular-sodium transport. The lysosomal inhibitor chloroquine prevented the D4R-induced NCC-reduction. A shortened NCC half-life was suggested by its decay under cycloheximide-chase. Ubiquitin-specific-protease 48 (USP48, a deubiquitinating enzyme) was increased in the kidneys and cells with Drd4-deficiency while D4R stimulation decreased it in vitro and reduction of USP48 with siRNA decreased NCC expression. The mice carrying human D4.7 variant or with renal reduction of D4R developed hypertension with increased NCC. ConclusionOur data demonstrates that D4R downregulates NCC by promoting USP48-associated deubiquitination and subsequent internalization, lysosome relocation and degradation.

physiology↗