Nephron specific ATP6AP2 knockout increases urinary excretion of fatty acids and decreases renal cortical megalin expression.

ATP6AP2 knockout in the renal nephron impairs receptor-mediated endocytosis, increasing urinary albumin and glucose excretion and impairing weight gain. Nonesterified fatty acids (NEFA) in urine are bound to albumin and reabsorbed in the proximal tubule through receptor-mediated endocytosis by the megalin-cubilin complex. We hypothesized that ATP6AP2 knockout increases urinary NEFA excretion through a reduction in megalin.

Renal Hypokalemia: An Endocrine Perspective.

The majority of disorders that cause renal potassium wasting present with abnormalities in adrenal hormone secretion. While these findings frequently lead patients to seek endocrine evaluation, clinicians often struggle to accurately diagnose these conditions, delaying treatment and adversely impacting patient care. At the same time, growing insight into the genetic and molecular basis of these disorders continues to improve their diagnosis and management.

Basal cortisol levels do not predict adrenal responsiveness in acute decompensated cirrhosis.

Objective: Morning total cortisol (TC) levels have been shown to predict adrenal dysfunction (AD) in the general population, but their utility in cirrhosis is unknown.

Methods: A retrospective cohort study was performed including all noncritically ill patients at our institution between 2011 and 2022 admitted with acute decompensated cirrhosis who underwent standard-dose adrenocorticotropic hormone (ACTH) stimulation testing. Adrenal dysfunction was defined as an increase in TC (delta TC) level <9 µg/dl 60 minutes after ACTH dosing.

Decoding Angiotensin Receptors: TOMAHAQ-Based Detection and Quantification of Angiotensin Type-1 and Type-2 Receptors.

Background The renin-angiotensin system plays a crucial role in human physiology, and its main hormone, angiotensin, activates 2 G-protein-coupled receptors, the angiotensin type-1 and type-2 receptors, in almost every organ. However, controversy exists about the location, distribution, and expression levels of these receptors. Concerns have been raised over the low sensitivity, low specificity, and large variability between lots of commercially available antibodies for angiotensin type-1 and type-2 receptors, which makes it difficult to reconciliate results of different studies.

Relative adrenal insufficiency in the non-critically ill patient with cirrhosis: A systematic review and meta-analysis.

Background & Aims: Characterization of relative adrenal insufficiency (RAI) in cirrhosis is heterogeneous with regard to studied patient populations and diagnostic methodology. We aimed to describe the prevalence and prognostic importance of RAI in non-critically ill patients with cirrhosis.

Methods: A systematic review and meta-analysis was performed using MeSH terms and Boolean operators to search five large databases (Ovid-MEDLINE, ScienceDirect, Web of Science, Cochrane Library and ClinicalTrials.

Short-term Outcomes of Hypertensive Crises in Patients with Orthostatic Hypotension.

Supine hypertension-orthostatic hypotension disease poses a management challenge to clinicians. Data on short term outcomes of patients with orthostatic hypotension (OH) who are hospitalized with hypertensive (HTN) crises is lacking. The Nationwide Readmission Database 2016-2019 was queried for all hospitalizations of HTN crises.

Adrenal Insufficiency in Cirrhosis.

Hypothalamus-pituitary-adrenal axis assessment in patients with cirrhosis is challenging. The phenotype of fatigue, hypotension, electrolyte disarray, and abdominal pain characterizing primary adrenal insufficiency (AI) overlaps significantly with decompensated liver disease. Reliance on total cortisol assays in hypoproteinemic states is problematic, yet abnormal stimulated levels in cirrhosis are associated with poor clinical outcomes.

Serum Concentrations of Losartan Metabolites Correlate With Improved Physical Function in a Pilot Study of Prefrail Older Adults.

Losartan is an oral antihypertensive agent that is rapidly metabolized to EXP3174 (angiotensin-subtype-1-receptor blocker) and EXP3179 (peroxisome proliferator-activated receptor gamma [PPARγ] agonist), which was shown in animal studies to reduce inflammation, enhance mitochondrial energetics, and improve muscle repair and physical performance. We conducted an exploratory pilot study evaluating losartan treatment in prefrail older adults (age 70-90 years, N = 25). Participants were randomized to control (placebo) or treatment (daily oral losartan beginning at 25 mg per day and increasing every 8 weeks) for a total of 6 months.

Angiotensin Type-2 Receptors: Transducers of Natriuresis in the Renal Proximal Tubule.

Angiotensin II (Ang II) type-2 receptors (ATR) are expressed in the adult kidney, prominently in renal proximal tubule cells (RPTCs), and play an important role in opposing renal sodium (Na) retention induced by Ang II stimulation of Ang II type-1 receptor (ATR). Natriuresis induced by ATR blockade is due at least in part to ATR activation and whole body deletion of ATRs reduces the natriuretic response to increased blood pressure (BP). The major endogenous ATR agonist mediating the natriuretic response is Ang III, the Ang II heptapeptide metabolite generated by aminopeptidase A, and the principal nephron site mediating inhibition of Na reabsorption by the ATR is the renal proximal tubule (RPT).

Relation of Type 2 Myocardial Infarction and Readmission With Type 1 Myocardial Infarction in Hypertensive Crises (from a Nationwide Analysis).

Type 2 myocardial infarction (T2MI) is an ischemic injury that occurs due to a mismatch between myocardial oxygen supply and demand. T2MI can occur with hypertensive crisis. Nevertheless, the impact of T2MI on hypertensive crisis outcome is poorly understood due to limited data.

Knockout of Nephron ATP6AP2 Impairs Proximal Tubule Function and Prevents High-Fat Diet-Induced Obesity in Male Mice.

ATP6AP2 expression is increased in the nephron during high-fat diet (HFD) and its knockout (ATP6AP2 KO) reduces body weight (WT) in mice. We evaluated the contribution of ATP6AP2 to urinary glucose (UG) and albumin (Ualb) handling during HFD. We hypothesized that nephron ATP6AP2 KO increases UG and Ualb and minimizes HFD-induced obesity.

Novel regulation of renal gluconeogenesis by Atp6ap2 in response to high fat diet via PGC1-α/AKT-1 pathway.

Recent studies suggested that renal gluconeogenesis is substantially stimulated in the kidney in presence of obesity. However, the mechanisms responsible for such stimulation are not well understood. Recently, our laboratory demonstrated that mice fed high fat diet (HFD) exhibited increase in renal Atp6ap2 [also known as (Pro)renin receptor] expression.

Pro-renin receptor suppresses mitochondrial biogenesis and function via AMPK/SIRT-1/ PGC-1α pathway in diabetic kidney.

Abnormal mitochondrial biogenesis and function has been linked to multiple diseases including diabetes. Recently, we demonstrated the role of renal (Pro)renin receptor (PRR) in the dysregulation of mitochondria. We hypothesized that PRR contributes to the reduction of mitochondrial biogenesis and function in diabetic kidney via PGC-1α/AMPK/SIRT-1 signaling pathway.

(Pro)renin receptor contributes to renal mitochondria dysfunction, apoptosis and fibrosis in diabetic mice.

Recently we demonstrated that increased renal (Pro)renin receptor (PRR) expression in diabetes contributes to development of diabetic kidney disease. However, the exact mechanisms involving PRR activity and diabetic kidney dysfunction are unknown. We hypothesized that PRR is localized in renal mitochondria and contributes to renal fibrosis and apoptosis through oxidative stress-induced mitochondria dysfunction.

(Pro)Renin receptor mediates obesity-induced antinatriuresis and elevated blood pressure via upregulation of the renal epithelial sodium channel.

Recent studies have demonstrated that the renal (pro)renin receptor (PRR) regulates expression of the alpha subunit of the epithelial sodium channel (α-ENaC). In this study we hypothesized that the renal PRR mediates high fat diet (HFD)-induced sodium retention and elevated systolic blood pressure (SBP) by enhancing expression of the epithelial sodium channel (α-ENaC). In our study we used a recently developed inducible nephron specific PRR knockout mouse.

Liver-specific rescuing of CEACAM1 reverses endothelial and cardiovascular abnormalities in male mice with null deletion of Ceacam1 gene.

Objective: Mice with global null mutation of Ceacam1 (Cc1), display impairment of insulin clearance that causes hyperinsulinemia followed by insulin resistance, elevated hepatic de novo lipogenesis, and visceral obesity. In addition, they manifest abnormal vascular permeability and elevated blood pressure. Liver-specific rescuing of Ceacam1 reversed all of the metabolic abnormalities in Cc1 mice.

The Jewel in the Crown: Specific Aims Section of Investigator-Initiated Grant Proposals.

The specific aims section of National Institutes of Health and other grants is the most important component, as it summarizes the scientific premise, gap in current knowledge, hypotheses, methods, and expected results of the project proposed. The reviewer usually reads this section first and forms an immediate opinion, usually confirmed on reading the entire grant. This treatise reviews the philosophical background underlying generation of hypotheses, emphasizes the important characteristics of the specific aims section, and offers a point-by-point roadmap for writing.

Prorenin receptor mediates inflammation in renal ischemia.

We hypothesized that PRR contributes to renal inflammation in the 2-kidney, 1-clip (2K1C) renal ischaemia model. Male Sprague-Dawley rats were fed normal sodium diet. Blood pressure (BP) was obtained on days 0 and 28 after left renal artery clipping that reduced renal blood flow by 40%.

Intrarenal Angiotensin-Converting Enzyme: the Old and the New.

Purpose Of Review: The intrarenal renin-angiotensin-aldosterone system (RAS) is an independent paracrine hormonal system with an increasingly prominent role in hypertension and renal disease. Two enzyme components of this system are angiotensin-converting enzyme (ACE) and more recently discovered ACE2. The purpose of this review is to describe recent discoveries regarding the roles of intrarenal ACE and ACE2 and their interaction.

Autophagy upregulates (pro)renin receptor expression via reduction of P62/SQSTM1 and activation of ERK1/2 signaling pathway in podocytes.

Autophagy plays a major role in podocytes health and disease. P62, also known as sequestosome-1 (SQSTM1), is a marker for autophagic activity and is required for the formation and degradation of ubiquitnated protein by autophagy. Knockout of p62 enhanced extracellular signal-regulated kinases (ERK1/2) activity.

Interaction of the renin angiotensin and cox systems in the kidney.

Cyclooxygenase-2 (COX-2) plays an important role in mediating actions of the renin-angiotensin system (RAS). This review sheds light on the recent developments regarding the complex interactions between components of RAS and COX-2; and their implications on renal function and disease. COX-2 is believed to counter regulate the effects of RAS activation and therefore counter balance the vasoconstriction effect of Ang II.

(Pro)renin receptor contributes to regulation of renal epithelial sodium channel.

Background: Recent studies reported increased (Pro)renin receptor (PRR) expression during low-salt intake. We hypothesized that PRR plays a role in regulation of renal epithelial sodium channel (ENaC) through serum and glucocorticoid-inducible kinase isoform 1 (SGK-1)-neural precursor cell expressed, developmentally downregulated 4-2 (Nedd4-2) signaling pathway.

Method: Male Sprague-Dawley rats on normal-sodium diet and mouse renal inner medullary collecting duct cells treated with NaCl at 130  mmol/l (normal salt), or 63  mmol/l (low salt) were studied.