scholarly journals WNK bodies cluster WNK4 and SPAK/OSR1 to promote NCC activation in hypokalemia

2020 ◽  
Vol 318 (1) ◽  
pp. F216-F228 ◽  
Author(s):  
Martin N. Thomson ◽  
Catherina A. Cuevas ◽  
Tim M. Bewarder ◽  
Carsten Dittmayer ◽  
Lauren N. Miller ◽  
...  
Keyword(s):  
Apical Membrane ◽  
Genetically Engineered ◽  
Nephron Segments ◽  
Mosaic Expression ◽  
Kinase Cascade ◽  
Wnk Kinases ◽  
Feeding Diets ◽  
And Oxidative Stress ◽  
Deficient Mice ◽  
Specific Deletion

K+ deficiency stimulates renal salt reuptake via the Na+-Cl− cotransporter (NCC) of the distal convoluted tubule (DCT), thereby reducing K+ losses in downstream nephron segments while increasing NaCl retention and blood pressure. NCC activation is mediated by a kinase cascade involving with no lysine (WNK) kinases upstream of Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1). In K+ deficiency, WNKs and SPAK/OSR1 concentrate in spherical cytoplasmic domains in the DCT termed “WNK bodies,” the significance of which is undetermined. By feeding diets of varying salt and K+ content to mice and using genetically engineered mouse lines, we aimed to clarify whether WNK bodies contribute to WNK-SPAK/OSR1-NCC signaling. Phosphorylated SPAK/OSR1 was present both at the apical membrane and in WNK bodies within 12 h of dietary K+ deprivation, and it was promptly suppressed by K+ loading. In WNK4-deficient mice, however, larger WNK bodies formed, containing unphosphorylated WNK1, SPAK, and OSR1. This suggests that WNK4 is the primary active WNK isoform in WNK bodies and catalyzes SPAK/OSR1 phosphorylation therein. We further examined mice carrying a kidney-specific deletion of the basolateral K+ channel-forming protein Kir4.1, which is required for the DCT to sense plasma K+ concentration. These mice displayed remnant mosaic expression of Kir4.1 in the DCT, and upon K+ deprivation, WNK bodies developed only in Kir4.1-expressing cells. We postulate a model of DCT function in which NCC activity is modulated by plasma K+ concentration via WNK4-SPAK/OSR1 interactions within WNK bodies.

scholarly journals Mesenchymal Stem Cell-Specific and Preosteoblast-Specific Ablation of TSC1 in Mice Lead to Severe and Slight Spinal Dysplasia, Respectively

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Cheng Yang ◽  
Jianwen Liao ◽  
Pinglin Lai ◽  
Hai Huang ◽  
Shicai Fan ◽  
...  
Keyword(s):  
Stem Cell ◽  
Body Size ◽  
Mesenchymal Stem Cell ◽  
Endochondral Ossification ◽  
Intervertebral Discs ◽  
Tsc1 Gene ◽  
Spine Development ◽  
Old Mice ◽  
Deficient Mice ◽  
Specific Deletion

Background. TSC1-related signaling plays a pivotal role in intramembranous and endochondral ossification processes during skeletogenesis. This study was aimed at determining the significance of the TSC1 gene at different stages of spinal development. Materials and Methods. TSC1-floxed mice (TSC1flox/flox) were crossed with Prrx1-Cre or BGLAP-Cre transgenic mice or mesenchymal stem cell- and osteoblast-specific TSC1-deficient mice, respectively. Somatic and vertebral differences between WT and Prrx1-TSC1 null mice were examined at 4 weeks after birth. Results. No apparent body size abnormalities were apparent in newborn and 4-week- to 2-month-old mice with BGLAP-Cre driver-depleted TSC1. Vertebral and intervertebral discs displayed strong dysplasia in Prrx1-TSC1 null mice. In contrast, vertebrae were only slightly affected, and intervertebral discs from skeletal preparations displayed no apparent changes in BGLAP-TSC1 null mice. Conclusion. Our data suggest that the TSC1 gene is crucial for endochondral ossification during postnatal spine development but plays discriminative roles at different stages. Mesenchymal stem cell-specific ablation of TSC1 led to severe spinal dysplasia at early stages of endochondral ossification while osteoblast-specific deletion of TSC1 affected vertebrae slightly and had no detectable effects on intervertebral discs.

Epithelial Ca2+ channels sensitive to dihydropyridines and activated by hyperpolarizing voltages

1994 ◽  
Vol 267 (1) ◽  
pp. C157-C165 ◽  
Author(s):  
H. Matsunaga ◽  
B. A. Stanton ◽  
F. A. Gesek ◽  
P. A. Friedman
Keyword(s):  
Open Channel ◽  
Single Channel ◽  
Apical Membrane ◽  
Channel Activity ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Nephron Segments ◽  
Convoluted Tubules ◽  
Ca2 Channels ◽  
In Cells

Parathyroid hormone (PTH) increases transcellular Ca2+ absorption in renal cortical thick ascending limbs and distal convoluted tubules (DCT). In cells isolated from these nephron segments, PTH increases Ca2+ uptake by a pathway that is sensitive to dihydropyridine-type agonists and antagonists (B. J. Bacskai and P. A. Friedman. Nature Lond. 347: 388-391, 1990). Patch-clamp techniques were used to identify Ca(2+)-permeable channels in DCT cells. Channel activity was detectable in cell-attached patches only in cells pretreated with PTH. Ca2+ channels exhibited prolonged open times (seconds), had a low single-channel conductance (2.1 pS), and open channel probability increased at hyperpolarizing voltages (-50 to -90 mV). Channel activity was sensitive to dihydropyridine-type compounds, nifedipine, and BAY K8644, as was Ca2+ uptake. However, Ca2+ entry was insensitive to verapamil or omega-conotoxin. These results demonstrate that these channels mediate PTH-stimulated apical membrane Ca2+ entry in DCT cells, which are the principal Ca(2+)-transporting cells of the kidney.

scholarly journals Discrete Role for Cytosolic Phospholipase A2α in Platelets

2002 ◽  
Vol 196 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Dennis A. Wong ◽  
Yoshihiro Kita ◽  
Naonori Uozumi ◽  
Takao Shimizu
Keyword(s):  
Therapeutic Potential ◽  
Genetically Engineered ◽  
Collagen Receptors ◽  
Cytosolic Phospholipase ◽  
Genetically Engineered Mice ◽  
Cytosolic Pla2 ◽  
In Vivo Effects ◽  
Deficient Mice

Among several different types of phospholipase A2 (PLA2), cytosolic PLA2 (cPLA2)α and group IIA (IIA) secretory PLA2 (sPLA2) have been studied intensively. To determine the discrete roles of cPLA2α in platelets, we generated two sets of genetically engineered mice (cPLA2α−/−/sPLA2-IIA−/− and cPLA2α−/−/sPLA2-IIA+/+) and compared their platelet function with their respective wild-type C57BL/6J mice (cPLA2α+/+/sPLA2-IIA−/−) and C3H/HeN (cPLA2α+/+/sPLA2-IIA+/+). We found that cPLA2α is needed for the production of the vast majority of thromboxane (TX)A2 with collagen stimulation of platelets. In cPLA2α-deficient mice, however, platelet aggregation in vitro is only fractionally decreased because small amounts of TX produced by redundant phospholipase enzymes sufficiently preserve aggregation. In comparison, adenosine triphosphate activation of platelets appears wholly independent of cPLA2α and sPLA2-IIA for aggregation or the production of TX, indicating that these phospholipases are specifically linked to collagen receptors. However, the lack of high levels of TX limiting vasoconstriction explains the in vivo effects seen: increased bleeding times and protection from thromboembolism. Thus, cPLA2α plays a discrete role in the collagen-stimulated production of TX and its inhibition has a therapeutic potential against thromboembolism, with potentially limited bleeding expected.

scholarly journals Flaxseed Oil Containingα-Linolenic Acid Ester of Plant Sterol Improved Atherosclerosis in ApoE Deficient Mice

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Hao Han ◽  
Peipei Yan ◽  
Li Chen ◽  
Cheng Luo ◽  
Hui Gao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Linolenic Acid ◽  
High Fat Diet ◽  
Acid Ester ◽  
Flaxseed Oil ◽  
Apoe Ko Mice ◽  
Underlying Mechanisms ◽  
And Oxidative Stress ◽  
Deficient Mice ◽  
Anti Inflammation

Plant sterols (PS) have potential preventive function in atherosclerosis due to their cholesterol-lowering ability. Dietaryα-linolenic acid in flaxseed oil is associated with a reduction in cardiovascular events through its hypolipidemic and anti-inflammation properties. This study was designed to evaluate the effects of flaxseed oil containingα-linolenic acid ester of PS (ALA-PS) on atherosclerosis and investigate the underlying mechanisms. C57BL/6 mice were administered a regular diet and apoE knockout (apoE-KO) mice were given a high fat diet alone or supplemented with 5% flaxseed oil with or without 3.3% ALA-PS for 18 weeks. Results demonstrated that flaxseed oil containing ALA-PS was synergistically interaction in ameliorating atherosclerosis as well as optimizing overall lipid levels, inhibiting inflammation and reducing oxidative stress. These data were associated with the modification effects on expression levels of genes involved in lipid metabolism (PPARα, HMGCR, and SREBPs), inflammation (IL-6, TNF, MCP-1, and VCAM-1), and oxidative stress (NADPH oxidase).

Dietary restriction reduces atherosclerosis and oxidative stress in the aorta of apolipoprotein E-deficient mice

2002 ◽  
Vol 123 (8) ◽  
pp. 1121-1131 ◽  
Author(s):  
ZhongMao Guo ◽  
Felicia Mitchell-Raymundo ◽  
Hong Yang ◽  
Yuji Ikeno ◽  
James Nelson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Apolipoprotein E ◽  
Dietary Restriction ◽  
And Oxidative Stress ◽  
Deficient Mice

scholarly journals PRAK Promotes the Pathogen Clearance by Macrophage Through Regulating Autophagy and Inflammasome Activation

2021 ◽  
Vol 12 ◽  
Author(s):  
Ligu Mi ◽  
Yan Wang ◽  
Hui Xu ◽  
Yu Wang ◽  
Jia Wu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Bacterial Load ◽  
Peritoneal Macrophages ◽  
Inflammasome Activation ◽  
Intracellular Pathogens ◽  
Mhc Ii ◽  
Autophagy Induction ◽  
Pathogen Clearance ◽  
Deficient Mice ◽  
Specific Deletion

The p38 regulated/activated protein kinase (PRAK) is a protein kinase downstream of p38MAPK. The present study investigated its function in the macrophage. Myeloid-specific deletion of Prak resulted in a significant reduction in F4/80+CD11b+ peritoneal macrophages with decreased expression of MHC-II and CD80. Upon infection with Listeria monocytogenes, Prak-deficient mice demonstrated an increased mortality, which was accompanied by a higher bacterial load in multiple tissues and elevated levels of proinflammatory cytokines in the serum. While the Prak-deficient macrophage showed similar potency in phagocytosis assays, its bactericidal activity was severely impaired. Moreover, Prak deficiency was associated with defects in ROS production, inflammasome activation as well as autophagy induction. Therefore, PRAK critically contributes to the clearance of intracellular pathogens by affecting multiple aspects of the macrophage function.

Expression of isoforms of the Na+/H+exchanger in M-1 mouse cortical collecting duct cells

2002 ◽  
Vol 282 (4) ◽  
pp. F649-F654 ◽  
Author(s):  
C. Hill ◽  
A. N. Giesberts ◽  
S. J. White
Keyword(s):  
Intracellular Ph ◽  
Apical Membrane ◽  
Collecting Duct ◽  
Extracellular Nucleotides ◽  
Cortical Collecting Duct ◽  
Intracellular Acidification ◽  
Basolateral Membranes ◽  
Nephron Segments ◽  
Collecting Duct Cells ◽  
Nhe Isoforms

Na+/H+ exchanger (NHE) proteins perform a variety of functions in the kidney and are differentially distributed among nephron segments. The purpose of this study was to identify NHE isoforms in murine M-1 cells as a model of cortical collecting duct principal cells. It was found that mRNAs corresponding to NHE1, NHE2, and NHE4 are expressed in M-1 cells. NHE-dependent regulation of intracellular pH (pHi) was investigated in the absence of extracellular HCO[Formula: see text]. Application of a 20 mM NH4Cl pulse resulted in a reversible intracellular acidification from which recovery was partially inhibited by application of 1 mM amiloride to either the apical or the basolateral membranes and was abolished when amiloride was applied to both sides of the monolayers, which suggests that NHEs are expressed in both the apical and the basolateral cell membranes of M-1 cells. The purinergic agonists ATP and benzoylbenzoyl-ATP caused a reduction of pHi when applied to the apical membrane, which suggests pHi may be influenced by extracellular nucleotides in the luminal fluid of the cortical collecting duct.

Red cells from glutathione peroxidase-1–deficient mice have nearly normal defenses against exogenous peroxides

Blood ◽  
2000 ◽  
Vol 96 (5) ◽  
pp. 1985-1988 ◽  
Author(s):  
Robert M. Johnson ◽  
Gerard Goyette ◽  
Yaddanapudi Ravindranath ◽  
Ye-Shih Ho
Keyword(s):  
Glutathione Peroxidase ◽  
Membrane Lipids ◽  
Genetically Engineered ◽  
Red Cells ◽  
Slight Reduction ◽  
Red Cell ◽  
Simultaneous Exposure ◽  
High Exposure ◽  
Glutathione Peroxidase 1 ◽  
Deficient Mice

The role of glutathione peroxidase in red cell anti-oxidant defense was examined using erythrocytes from mice with a genetically engineered disruption of the glutathione peroxidase-1 (GSHPx-1) gene. Because GSHPx-1 is the sole glutathione peroxidase in the erythrocyte, all red cell GSH peroxidase activity was eliminated. Oxidation of hemoglobin and membrane lipids, using the cis-parinaric acid assay, was determined during oxidant challenge from cumene hydroperoxide and H2O2. No difference was detected between wild-type red cells and GSHPx-1–deficient cells, even at high H2O2 exposures. Thus, GSHPx-1 appears to play little or no role in the defense of the erythrocyte against exposure to peroxide. Simultaneous exposure to an H2O2 flux and the catalase inhibitor 3-amino-1,2,4-triazole supported this conclusion. Hemoglobin oxidation occurred only when catalase was depleted. Circulating erythrocytes from the GSHPx-1–deficient mice exhibited a slight reduction in membrane thiols, indicating that high exposure to peroxides might occur naturally in the circulation.

scholarly journals Altered expression and function of canalicular transporters during early development of cholestatic liver injury in Abcb4-deficient mice

2014 ◽  
Vol 306 (8) ◽  
pp. G670-G676 ◽  
Author(s):  
Shi-Ying Cai ◽  
Albert Mennone ◽  
Carol J. Soroka ◽  
James L. Boyer
Keyword(s):  
Bile Acid ◽  
Apical Membrane ◽  
Wild Type ◽  
Wild Type Littermate ◽  
Altered Expression ◽  
Canalicular Transporters ◽  
Immunofluorescence Labeling ◽  
And Function ◽  
Cholestatic Liver Injury ◽  
Deficient Mice

Deficiency of ABCB4 is associated with several forms of cholestasis in humans. Abcb4−/− mice also develop cholestasis, but it remains uncertain what role other canalicular transporters play in the development of this disease. We examined the expression of these transporters in Abcb4−/− mice compared with their wild-type littermate controls at ages of 10 days and 3, 6, and 12 wk. Elevated plasma bile acid levels were already detected at 10 days and at all ages thereafter in Abcb4−/− mice. The expression of Bsep, Mrp2, Atp8b1, Abcg5, and Abcg8 liver proteins did not change at 10 days, but Bsep, Mrp2, and Atp8b1 were reduced, whereas Abcg5 and Abcg8 expression were increased in Abcb4−/− mice at all later ages. Lower bile acid concentrations were also detected in the bile of 6-wk-old Abcb4−/− mice. Immunofluorescence labeling revealed distorted canalicular architecture in the liver tissue by 12 wk in Abcb4−/− mice. Whereas Bsep and Mrp2 remained associated with the apical membrane, Atp8b1 was now localized in discrete punctuate structures adjacent to the canalicular membrane in these mice. Expression of Bsep mRNA was increased in the livers of 10-day-old Abcb4−/− mice, whereas Ost-α was decreased. By 12 wk, Bsep, Mrp2, and Abcg5 mRNA were all increased, whereas Ost-α and Ntcp were reduced. These findings indicate that canalicular transporters that determine the formation of bile are altered early in the development of cholestasis in Abcb4−/− mice and may contribute to the pathogenesis of cholestasis in this disorder.

Sign in / Sign up

Export Citation Format

Share Document