scholarly journals Inhibition of K+secretion in the distal nephron in nephrotic syndrome: possible role of albuminuria

2011 ◽  
Vol 589 (14) ◽  
pp. 3611-3621 ◽  
Author(s):  
Marc Fila ◽  
Gaëlle Brideau ◽  
Luciana Morla ◽  
Lydie Cheval ◽  
Georges Deschênes ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Distal Nephron ◽  
K Secretion

scholarly journals With-No-Lysine Kinase 1 (WNK1) Augments TRPV4 Function in the Aldosterone-Sensitive Distal Nephron

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1482
Author(s):  
Viktor N. Tomilin ◽  
Kyrylo Pyrshev ◽  
Naghmeh Hassanzadeh Khayyat ◽  
Oleg Zaika ◽  
Oleh Pochynyuk
Keyword(s):  
Collecting Duct ◽  
Chinese Hamster ◽  
Dominant Negative ◽  
K Channel ◽  
Apical Plasma Membrane ◽  
Dependent Manner ◽  
Distal Nephron ◽  
Potassium Homeostasis ◽  
Wnk Kinases ◽  
K Secretion

Kidneys play a central role in regulation of potassium homeostasis and maintenance of plasma K+ levels within a narrow physiological range. With-no-lysine (WNK) kinases, specifically WNK1 and WNK4, have been recognized to regulate K+ balance, in part, by orchestrating maxi K+ channel (BK)-dependent K+ secretion in the aldosterone-sensitive distal nephron (ASDN), which includes the connecting tubule and collecting duct. We recently demonstrated that the Ca2+-permeable TRPV4 channel is essential for BK activation in the ASDN. Furthermore, high K+ diet increases TRPV4 activity and expression largely in an aldosterone-dependent manner. In the current study, we aimed to test whether WNK kinases contribute to regulation of TRPV4 activity and its stimulation by aldosterone. Systemic inhibition of WNK with WNK463 (1 mg/kgBW for 3 days) markedly decreased TRPV4-dependent Ca2+ influx in freshly isolated split-opened collecting ducts. Aldosterone greatly increased TRPV4 activity and expression in cultured mpkCCDc14 cells and this effect was abolished in the presence of WNK463. Selective inhibition of WNK1 with WNK-in-11 (400 nM, 24 h) recapitulated the effects of WNK463 on TRPV4-dependent Ca2+ influx. Interestingly, WNK-in-11 did not interfere with up-regulation of TRPV4 expression by aldosterone, but prevented translocation of the channel to the apical plasma membrane. Furthermore, co-expression of TRPV4 and WNK1 into Chinese hamster ovary (CHO) cells increased the macroscopic TRPV4-dependent cation currents. In contrast, over-expression of TRPV4 with a dominant negative WNK1 variant (K233M) decreased the whole-cell currents, suggesting both stimulatory and permissive roles of WNK1 in regulation of TRPV4 activity. Overall, we show that WNK1 is essential for setting functional TRPV4 expression in the ASDN at the baseline and in response to aldosterone. We propose that this new mechanism contributes to regulation of K+ secretion and, by extension, urinary K+ levels to maintain systemic potassium homeostasis.

scholarly journals Role of ‘catalytic’ iron in an animal model of minimal change nephrotic syndrome

1996 ◽  
Vol 49 (2) ◽  
pp. 370-373 ◽  
Author(s):  
Norishi Ueda ◽  
Radhakrishna Baliga ◽  
Sudhir V. Shah
Keyword(s):  
Animal Model ◽  
Nephrotic Syndrome ◽  
Minimal Change Nephrotic Syndrome ◽  
Minimal Change

scholarly journals Evidence for a role of angiotensin converting enzyme 2 in proteinuria of idiopathic nephrotic syndrome

2019 ◽  
Vol 39 (1) ◽  
Author(s):  
Roberta da Silva Filha ◽  
Sérgio Veloso Brant Pinheiro ◽  
Thiago Macedo e Cordeiro ◽  
Victor Feracin ◽  
Érica Leandro Marciano Vieira ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Idiopathic Nephrotic Syndrome ◽  
Renin Angiotensin System ◽  
Cross Sectional Study ◽  
Healthy Controls ◽  
Ang Ii ◽  
Cross Sectional ◽  
Angiotensin Converting Enzyme 2 ◽  
Inflammatory Molecules

AbstractIntroduction: Renin angiotensin system (RAS) plays a role in idiopathic nephrotic syndrome (INS). Most studies investigated only the classical RAS axis. Therefore, the aims of the present study were to evaluate urinary levels of RAS molecules related to classical and to counter-regulatory axes in pediatric patients with INS, to compare the measurements with levels in healthy controls and to search for associations with inflammatory molecules, proteinuria and disease treatment. Subjects and methods: This cross-sectional study included 31 patients with INS and 19 healthy controls, matched for age and sex. Patients and controls were submitted to urine collection for measurement of RAS molecules [Ang II, Ang-(1-7), ACE and ACE2] by enzyme immunoassay and cytokines by Cytometric Bead Array. Findings in INS patients were compared according to proteinuria: absent (<150 mg/dl, n = 15) and present (≥150 mg/dl, n = 16). Results: In comparison to controls, INS patients had increased Ang II, Ang-(1-7) and ACE, levels while ACE2 was reduced. INS patients with proteinuria had lower levels of ACE2 than those without proteinuria. ACE2 levels were negatively correlated with 24-h-proteinuria. Urinary concentrations of MCP-1/CCL2 were significantly higher in INS patients, positively correlated with Ang II and negatively with Ang-(1-7). ACE2 concentrations were negatively correlated with IP-10/CXCL-10 levels, which, in turn, were positively correlated with 24-h-proteinuria. Conclusion: INS patients exhibited changes in RAS molecules and in chemokines. Proteinuria was associated with low levels of ACE2 and high levels of inflammatory molecules.

scholarly journals New Aspects of Pathogenesis and Treatment of Membranous Glomerulopathy After the MENTOR Study

2020 ◽  
pp. 46-53
Author(s):  
Maurizio Salvadori ◽  
Aris Tsalouchos
Keyword(s):  
Nephrotic Syndrome ◽  
Adrenocorticotropic Hormone ◽  
Glomerular Diseases ◽  
The Past ◽  
Superior Efficacy ◽  
Novel Drugs ◽  
Membranous Glomerulopathy ◽  
Blocking Mechanisms ◽  
Antigenic Epitopes

Membranous nephropathy (MN) is the major cause of nephrotic syndrome in adults, accounting for 20% of cases with an annual incidence of 1 per 100,000 population. In the past 10 years, the role of podocytes has been identified. Environmental triggers in genetically predisposed patients can activate podocytes to exhibit antigenic epitopes, including PLA2R, THBS1, and NELL1, which become targets of specific autoantibodies with subsequent complement activation. The discovery of these mechanisms has opened a new horizon in the treatment of MN, and novel drugs are available with more specific mechanisms of action. Rituximab, a monoclonal antibody directed against CD20 expressed on B lymphocytes, has been used in several trials and appears to induce remission of nephrotic syndrome in 60% of patients (GEMRITUX trial). The recently published results of the MENTOR trial documented the superior efficacy of rituximab in patients observed for up to 24 months. In MN, the concept of targeting disease control has introduced novel therapies with specific blocking mechanisms, such as belimumab; nonspecific blocking mechanisms, such as those against adrenocorticotropic hormone; and new therapeutic options, such as ofatumumab, bortezomib, and eculizumab, which have recognised the pathological processes involved in the glomerular diseases.

scholarly journals Tubuloglomerular Disease With Cone-Shaped Epiphyses Associated With Hypomorphic Variant and a Novel p.Cys14Arg in the TTC21B Gene: A Case Report

2021 ◽  
Vol 9 ◽  
Author(s):  
Martin Bezdíčka ◽  
Dana Zemková ◽  
Sylva Skálová ◽  
Eva Hovorková ◽  
Miroslav Podhola ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Kidney Development ◽  
Kidney Biopsy ◽  
Intraflagellar Transport ◽  
X Ray ◽  
Heterozygous Variant ◽  
Renal Tubular ◽  
Nephrotic Range Proteinuria ◽  
Generation Sequencing

Monogenic nephrotic syndrome (NS) is associated with a resistance to initial glucocorticoid therapy and causative variants, which may be found in several genes influencing podocyte stability and kidney development. The TTC21B gene, which encodes the retrograde intraflagellar transport protein IFT139, is found mostly in association with ciliopathies in humans. The role of this protein in podocyte cytoskeleton stability was confirmed later and the mutated TTC21B also may be associated with proteinuric diseases, such as nephrotic syndrome. Our patient manifested as an infant with brachydactyly, nephrotic-range proteinuria, and renal tubular acidosis, and a kidney biopsy revealed focal segmental glomerulosclerosis (FSGS). Multiple phalangeal cone-shaped epiphyses of the hand were seen on X-ray. Next-generation sequencing revealed the well-described p.Pro209Leu heterozygous variant and a novel heterozygous p.Cys14Arg variant in the TTC21B gene. Our finding confirmed that the causative variants in the TTC21B gene may contribute to a spectrum of clinical features, such as glomerular proteinuric disease with tubulointerstitial involvement and skeletal abnormalities.

Potassium secretion and the regulation of distal nephron K channels

1999 ◽  
Vol 277 (6) ◽  
pp. F821-F825 ◽  
Author(s):  
Lawrence G. Palmer
Keyword(s):  
Regulatory Process ◽  
Distal Nephron ◽  
K Channels ◽  
Nephron Segments ◽  
High K ◽  
Potassium Secretion ◽  
K Transport

K-selective channels in the luminal membranes of distal nephron segments form a key pathway for the secretion of K ions into the urine. This process is important to the control of K balance, particularly under conditions of normal or high K intake. This brief review will cover three issues: 1) the identification of apical K channels, 2) the role of these channels in the maintenance of K homeostasis, and 3) the role of aldosterone in this regulatory process. The large amount of literature on renal K transport has been elegantly summarized in a recent review in this journal [G. Giebisch. Am. J. Physiol.274 ( Renal Physiol. 43): F817–F833, 1998]. Here I will focus on a few prominent unsolved problems.

Evidence of corticosteroid action along the nephron

1984 ◽  
Vol 246 (2) ◽  
pp. F111-F123 ◽  
Author(s):  
D. Marver
Keyword(s):  
Collecting Duct ◽  
Type I ◽  
Type Ii ◽  
Cortical Collecting Duct ◽  
Distal Nephron ◽  
Type Iii ◽  
Collecting Ducts ◽  
Collecting Tubule ◽  
Cortical Collecting Tubule

The kidney contains three classes of corticosteroid-binding proteins receptors. They include a mineralocorticoid-specific (Type I), a glucocorticoid-specific (Type II), and a corticosterone-specific (Type III) site. The Type I and Type III sites roughly parallel each other along the nephron, with maximal binding occurring in the late distal convoluted or connecting segment and the cortical and medullary collecting ducts. Type II sites occur throughout the nephron, with maximal concentrations appearing in the proximal tubule and the late distal convoluted-cortical collecting duct region. The function of the Type I sites in the connecting segment is unclear since chronic mineralocorticoid therapy does not influence the potential difference in this segment as it does in the cortical collecting tubule. Furthermore, the specific role of Type II versus Type III sites in the distal nephron is unknown. Finally, the possible influence of sodium on both latent and steroid-induced renal cortical and medullary Na-K-ATPase is discussed.

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