Drug Screening Using Normal Cell and Cancer Cell Mixture in an Automated 3D Cell Culture System.

Three-dimensional (3D) cell culture creates a more physiologically relevant environment for enhanced drug screening capabilities using microcarriers. An automated 3D system that integrates robotic manipulators, liquid handling systems, sensors, and environment control systems has the capacity to handle multiple samples in parallel, perform repetitive tasks, and provide real-time monitoring and analysis. This chapter describes a potential 3D cell culture drug screening model by combining renal proximal tubule cells as a representative normal cell line with cancer cell lines.

Renal autocrine neuropeptide FF (NPFF) signaling regulates blood pressure.

The kidney and brain play critical roles in the regulation of blood pressure. Neuropeptide FF (NPFF), originally isolated from the bovine brain, has been suggested to contribute to the pathogenesis of hypertension. However, the roles of NPFF and its receptors, NPFF-R1 and NPFF-R2, in the regulation of blood pressure, via the kidney, are not known.

Bridging the gaps in newborn screening programmes: Challenges and opportunities to detect haemoglobinopathies in Africa.

Background: Haemoglobinopathies, including sickle cell disease and β-thalassaemia, are monogenic disorders with a relatively higher prevalence among malaria-endemic areas in Africa. Despite this prevalence, most African countries lack the necessary resources for diagnosing and managing these debilitating conditions.

Aim: This study provides a critical review of newborn screening for detecting haemoglobinopathies in Africa, highlighting challenges and proposing strategies for improved diagnosis and management.

Peroxiredoxin-4 and Dopamine D5 Receptor Interact to Reduce Oxidative Stress and Inflammation in the Kidney.

Reactive oxygen species are highly reactive molecules generated in different subcellular compartments. Both the dopamine D5 receptor (DR) and endoplasmic reticulum (ER)-resident peroxiredoxin-4 (PRDX4) play protective roles against oxidative stress. This study is aimed at investigating the interaction between PRDX4 and DR in regulating oxidative stress in the kidney.

Inverse Salt Sensitivity of Blood Pressure Is Associated with an Increased Renin-Angiotensin System Activity.

High and low sodium diets are associated with increased blood pressure and cardiovascular morbidity and mortality. The paradoxical response of elevated BP in low salt diets, aka inverse salt sensitivity (ISS), is an understudied vulnerable 11% of the adult population with yet undiscovered etiology. A linear relationship between the number of single nucleotide polymorphisms (SNPs) in the dopamine D receptor ( rs6276 and 6277), and the sodium myo-inositol cotransporter 2 (, rs11074656), as well as decreased expression of these two genes in urine-derived renal proximal tubule cells (uRPTCs) isolated from clinical study participants suggest involvement of these cells in ISS.

Inverse Salt Sensitivity of Blood Pressure: Mechanisms and Potential Relevance for Prevention of Cardiovascular Disease.

Purpose Of Review: To review the etiology of inverse salt sensitivity of blood pressure (BP).

Recent Findings: Both high and low sodium (Na) intake can be associated with increased BP and cardiovascular morbidity and mortality. However, little is known regarding the mechanisms involved in the increase in BP in response to low Na intake, a condition termed inverse salt sensitivity of BP, which affects approximately 15% of the adult population.

Epithelial Sodium Channel Alpha Subunit (αENaC) Is Associated with Inverse Salt Sensitivity of Blood Pressure.

Salt sensitivity of blood pressure (BP) refers to an increase in BP following an increase in dietary salt, which is associated with increased incidence of cardiovascular disease and early death. However, decreased sodium intake also increases mortality and morbidity. Inverse salt sensitivity (ISS), defined as a paradoxical increase in BP on a low-salt diet, about 11% of the population, may be the cause of this phenomenon.

GRK4, A Potential Link between Hypertension and Breast Cancer.

Hypertension and breast cancer are two common diseases occurring in women. Clinical studies have shown increased breast cancer incidence in hypertensive women. Several lines of evidence demonstrate that G protein-coupled Receptor Kinase 4 (GRK4) could be a common risk factor for hypertension and breast cancer.

Comparative microsomal proteomics of a model lung cancer cell line NCI-H23 reveals distinct differences between molecular profiles of 3D and 2D cultured cells.

Lung cancer is the leading cause of cancer-related deaths in the USA and worldwide. Yet, about 95% of new drug candidates validated in preclinical phase eventually fail in clinical trials. Such a high attrition rate is attributed mostly to the inability of conventional two-dimensionally (2D) cultured cancer cells to mimic native three-dimensional (3D) growth of malignant cells in human tumors.

The Hypertension Related Gene G-Protein Coupled Receptor Kinase 4 Contributes to Breast Cancer Proliferation.

Purpose: Clinical studies have shown that breast cancer risk is increased in hypertensive women. The underlying molecular mechanism remains undetermined. The current study tests our hypothesis that G protein coupled receptor kinase 4 (GRK4) is a molecule that links hypertension and breast cancer.

Dopamine D receptor-mediated decreases in mitochondrial reactive oxygen species production are cAMP and autophagy dependent.

Overproduction of reactive oxygen species (ROS) plays an important role in the pathogenesis of hypertension. The dopamine D receptor (DR) is known to decrease ROS production, but the mechanism is not completely understood. In HEK293 cells overexpressing DR, fenoldopam, an agonist of the two D-like receptors, DR and DR, decreased the production of mitochondria-derived ROS (mito-ROS).

SNX-PXA-RGS-PXC Subfamily of SNXs in the Regulation of Receptor-Mediated Signaling and Membrane Trafficking.

The SNX-PXA-RGS-PXC subfamily of sorting nexins (SNXs) belongs to the superfamily of SNX proteins. SNXs are characterized by the presence of a common phox-homology (PX) domain, along with other functional domains that play versatile roles in cellular signaling and membrane trafficking. In addition to the PX domain, the SNX-PXA-RGS-PXC subfamily, except for SNX19, contains a unique RGS (regulators of G protein signaling) domain that serves as GTPase activating proteins (GAPs), which accelerates GTP hydrolysis on the G protein α subunit, resulting in termination of G protein-coupled receptor (GPCR) signaling.

The inositol pyrophosphate 5-InsP drives sodium-potassium pump degradation by relieving an autoinhibitory domain of PI3K p85α.

Sodium/potassium-transporting adenosine triphosphatase (Na/K-ATPase) is one of the most abundant cell membrane proteins and is essential for eukaryotes. Endogenous negative regulators have long been postulated to play an important role in regulating the activity and stability of Na/K-ATPase, but characterization of these regulators has been elusive. Mechanisms of regulating Na/K-ATPase homeostatic turnover are unknown.

Sorting nexin 1 loss results in increased oxidative stress and hypertension.

Acute renal depletion of sorting nexin 1 (SNX1) in mice results in blunted natriuretic response and hypertension due to impaired dopamine D receptor (D R) activity. We elucidated the molecular mechanisms for these phenotypes in Snx1 mice. These mice had increased renal expressions of angiotensin II type 1 receptor (AT R), NADPH oxidase (NOX) subunits, D R, and NaCl cotransporter.

Lipid rafts are required for effective renal D dopamine receptor function.

Effective receptor signaling is anchored on the preferential localization of the receptor in lipid rafts, which are plasma membrane platforms replete with cholesterol and sphingolipids. We hypothesized that the dopamine D receptor (D R) contains structural features that allow it to reside in lipid rafts for its activity. Mutation of C347 palmitoylation site and Y218 of a newly identified Cholesterol Recognition Amino Acid Consensus motif resulted in the exclusion of D R from lipid rafts, blunted cAMP response, impaired sodium transport, and increased oxidative stress in renal proximal tubule cells (RPTCs).

Stomach gastrin is regulated by sodium via PPAR-α and dopamine D1 receptor.

Gastrin, secreted by stomach G cells in response to ingested sodium, stimulates the renal cholecystokinin B receptor (CCKBR) to increase renal sodium excretion. It is not known how dietary sodium, independent of food, can increase gastrin secretion in human G cells. However, fenofibrate (FFB), a peroxisome proliferator-activated receptor-α (PPAR-α) agonist, increases gastrin secretion in rodents and several human gastrin-secreting cells, via a gastrin transcriptional promoter.

Dopamine D receptor modulates Wnt expression and control of cell proliferation.

The Wnt/β-catenin pathway is one of the most conserved signaling pathways across species with essential roles in development, cell proliferation, and disease. Wnt signaling occurs at the protein level and via β-catenin-mediated transcription of target genes. However, little is known about the underlying mechanisms regulating the expression of the key Wnt ligand Wnt3a or the modulation of its activity.

The Dopamine D Receptor and Angiotensin II Type-2 Receptor are Required for Inhibition of Sodium Transport Through a Protein Phosphatase 2A Pathway.

Activation of the renal DR (dopamine D-like receptor) or ATR (angiotensin II type-2 receptor), individually or both, simultaneously, is necessary in the normal regulation of renal sodium (Na) transport and blood pressure. However, little is known regarding the precise mechanism of this interaction. Pharmacological stimulation, membrane biotinylation, and cell surface immunofluorescence were used to study the effect of the DR/ATR interaction in human renal proximal tubule cells.

Sodium bicarbonate cotransporter NBCe2 gene variants increase sodium and bicarbonate transport in human renal proximal tubule cells.

Rationale: Salt sensitivity of blood pressure affects >30% of the hypertensive and >15% of the normotensive population. Variants of the electrogenic sodium bicarbonate cotransporter NBCe2 gene, SLC4A5, are associated with increased blood pressure in several ethnic groups. SLC4A5 variants are also highly associated with salt sensitivity, independent of hypertension.

Loss of renal SNX5 results in impaired IDE activity and insulin resistance in mice.

Aims/hypothesis: We hypothesised that renal sorting nexin 5 (SNX5) regulates the insulin-degrading enzyme (IDE) and, thus, circulating insulin levels. We therefore studied the dynamic interaction between SNX5 and IDE in human renal proximal tubule cells (hRPTCs), as well as in rat and mouse kidneys.

Methods: The regulation of IDE by SNX5 expressed in the kidney was studied in vitro and in vivo.

Urinary Sodium-to-Potassium Ratio Tracks the Changes in Salt Intake during an Experimental Feeding Study Using Standardized Low-Salt and High-Salt Meals among Healthy Japanese Volunteers.

The Na/K ratio is considered to be a useful index, the monitoring of which allows an effective Na reduction and K increase, because practical methods (self-monitoring devices and reliable individual estimates from spot urine) are available for assessing these levels in individuals. An intervention trial for lowering the Na/K ratio has demonstrated that a reduction of the Na/K ratio mainly involved Na reduction, with only a small change in K. The present study aimed to clarify the relationship between dietary Na intake and the urinary Na/K molar ratio, using standardized low- and high-salt diets, with an equal dietary K intake, to determine the corresponding Na/K ratio.

Gastrin stimulates renal dopamine production by increasing the renal tubular uptake of l-DOPA.

Gastrin is a peptide hormone that is involved in the regulation of sodium balance and blood pressure. Dopamine, which is also involved in the regulation of sodium balance and blood pressure, directly or indirectly interacts with other blood pressure-regulating hormones, including gastrin. This study aimed to determine the mechanisms of the interaction between gastrin and dopamine and tested the hypothesis that gastrin produced in the kidney increases renal dopamine production to keep blood pressure within the normal range.

The Renal Sodium Bicarbonate Cotransporter NBCe2: Is It a Major Contributor to Sodium and pH Homeostasis?

The sodium bicarbonate cotransporter (NBCe2, aka NBC4) was originally isolated from the human testis and heart (Pushkin et al. IUBMB Life 50:13-19, 2000). Subsequently, NBCe2 was found in diverse locations where it plays a role in regulating sodium and bicarbonate transport, influencing intracellular, extracellular, interstitial, and ultimately plasma pH (Boron et al.