Localization and Regulation of Claudin-14 in Experimental Models of Hypercalcemia

2020 ◽  
Author(s):  
Sebastian Frische ◽  
R. Todd Alexander ◽  
Patrícia Ferreira ◽  
Rebecca Tan ◽  
Weidong Wang ◽  
...  
Keyword(s):  
Cellular Localization ◽  
Stone Formation ◽  
Apical Cell ◽  
Experimental Models ◽  
Cell Junctions ◽  
Cell Periphery ◽  
Increased Risk ◽  
Junction Protein ◽  
Lacz Activity ◽  
Kidney Stone Formation

Variations in the CLDN14 gene have been linked to increased risk of hypercalciuria and kidney stone formation. However, the exact cellular localization of CLDN14 and its regulation remain to be fully delineated. To this end, we generated a novel antibody that allowed the detection of CLDN14 in paraffin-embedded renal sections. This showed CLDN14 to be detectable in the kidney only after induction of hypercalcemia in rodent models. Protein expression in kidney is localized exclusively to the thick ascending limbs (TAL), mainly restricted to the cortical and upper medullary portion of the kidney. However not all cells in the TAL expressed the tight junction protein. In fact, CLDN14 was primarily expressed in cells also expressing CLDN16, but devoid of CLDN10. CLDN14 appeared in very superficial apical cell domains and near cell junctions in a belt-like formation along the apical cell periphery. In transgenic mice, Cldn14 promotor-driven LacZ activity did not show complete colocalization with CLDN14 protein nor was it increased by hypercalcemia, suggesting that LacZ activity cannot be used as a marker for CLDN14 localization and regulation in this model. In conclusion, CLDN14, showed a restricted localization pattern in the apical domain of select cells of the TAL.

MT1-MMP collagenolytic activity is regulated through association with tetraspanin CD151 in primary endothelial cells

Blood ◽  
2008 ◽  
Vol 112 (8) ◽  
pp. 3217-3226 ◽  
Author(s):  
María Yañez-Mó ◽  
Olga Barreiro ◽  
Pilar Gonzalo ◽  
Alicia Batista ◽  
Diego Megías ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Ex Vivo ◽  
Experimental Models ◽  
Cell Junctions ◽  
Collagenolytic Activity ◽  
Cell Periphery ◽  
Α3β1 Integrin ◽  
Lung Endothelial Cells ◽  
Hemopexin Domain ◽  
Deficient Mice

Abstract MT1-MMP plays a key role in endothelial function, as underscored by the angiogenic defects found in MT1-MMP deficient mice. We have studied the molecular interactions that underlie the functional regulation of MT1-MMP. At lateral endothelial cell junctions, MT1-MMP colocalizes with tetraspanin CD151 (Tspan 24) and its associated partner α3β1 integrin. Biochemical and FRET analyses show that MT1-MMP, through its hemopexin domain, associates tightly with CD151, thus forming α3β1 integrin/CD151/MT1-MMP ternary complexes. siRNA knockdown of HUVEC CD151 expression enhanced MT1-MMP-mediated activation of MMP2, and the same activation was seen in ex vivo lung endothelial cells isolated from CD151-deficient mice. However, analysis of collagen degradation in these experimental models revealed a diminished MT1-MMP enzymatic activity in confined areas around the cell periphery. CD151 knockdown affected both MT1-MMP subcellular localization and its inclusion into detergent-resistant membrane domains, and prevented biochemical association of the metalloproteinase with the integrin α3β1. These data provide evidence for a novel regulatory role of tetraspanin microdomains on the collagenolytic activity of MT1-MMP and indicate that CD151 is a key regulator of MT1-MMP in endothelial homeostasis.

scholarly journals Effect of Black Tea Consumption on Urinary Risk Factors for Kidney Stone Formation

Nutrients ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 4434
Author(s):  
Roswitha Siener ◽  
Albrecht Hesse
Keyword(s):  
Risk Factors ◽  
Kidney Stone ◽  
Protective Factor ◽  
Fluid Intake ◽  
Stone Formation ◽  
Black Tea ◽  
Tea Consumption ◽  
Increased Risk ◽  
The Impact ◽  
Kidney Stone Formation

Copious fluid intake is the most essential nutritional measure in the treatment of urolithiasis, and is suggested to be a protective factor in the primary prevention of urinary stone formation. Although the intake of black tea contributes to daily fluid intake, the high oxalate content could outweigh the beneficial effect of urine dilution. The present study investigated the effect of black tea consumption on urinary risk factors for kidney stone formation. Ten healthy men received a standardized diet for a period of ten days. Subjects consumed 1.5 L/day of fruit tea (0 mg/day oxalate) during the 5-day control phase, which was replaced by 1.5 L/day of black tea (86 mg/day oxalate) during the 5-day test phase. Fractional and 24-h urines were obtained. The intake of black tea did not significantly alter 24-h urinary oxalate excretion. Urinary citrate, an important inhibitor of calcium stone formation, increased significantly, while the relative supersaturation of calcium oxalate, uric acid, and struvite remained unchanged. No significantly increased risk for kidney stone formation could be derived from the ingestion of black tea in normal subjects. Further research is needed to evaluate the impact of black tea consumption in kidney stone patients with intestinal hyperabsorption of oxalate.

scholarly journals Care and prevention during the COVID-19 pandemic quarantine: sedentary lifestyle and increased risk of kidney stones

2021 ◽  
pp. 45-50
Keyword(s):  
Physical Activity ◽  
Kidney Stones ◽  
Sedentary Lifestyle ◽  
Stone Formation ◽  
Noncommunicable Diseases ◽  
Major Health Problem ◽  
Major Health ◽  
Increased Risk ◽  
Tract Disease ◽  
Kidney Stone Formation

Currently, the issue of lifestyle combined with lack of physical activity in quarantine conditions during the COVID-19 pandemic has become a major health problem in many countries around the world. Increased inactivity is associated with increased obesity as well as decreased physical activity and general health. Kidney stones are the third most common urinary tract disease. Prevention of non-communicable diseases depends on controlling risk factors such as low levels of physical activity. Kidney stones are also among the noncommunicable diseases that can be prevented by changing behavioral habits. Physical activity is a behavior that has many proven health benefits and is one of the most effective ways to prevent chronic diseases. The aim of this study was to investigate sedentary lifestyle and its relationship with oxidative stress and kidney stone formation, and finally to provide medical solutions and recommendations.

scholarly journals DAPLE and MPDZ bind to each other and cooperate to promote apical cell constriction

2019 ◽  
Vol 30 (16) ◽  
pp. 1900-1910 ◽  
Author(s):  
Arthur Marivin ◽  
Mikel Garcia-Marcos
Keyword(s):  
G Protein ◽  
Cultured Cells ◽  
Apical Cell ◽  
Cell Junctions ◽  
Binding Motif ◽  
Apical Constriction ◽  
Protein Activation ◽  
Neuroepithelial Cells ◽  
Two Factors ◽  
Apical Junctions

Dishevelled-Associating Protein with a high frequency of LEucines (DAPLE) belongs to a group of unconventional activators of heterotrimeric G-proteins that are cytoplasmic factors rather than membrane proteins of the G-protein–coupled receptor superfamily. During neurulation, DAPLE localizes to apical junctions of neuroepithelial cells and promotes apical cell constriction via G-protein activation. While junctional localization of DAPLE is necessary for this function, the factors it associates with at apical junctions or how they contribute to DAPLE-mediated apical constriction are unknown. MPDZ is a multi-PDZ (PSD95/DLG1/ZO-1) domain scaffold present at apical cell junctions whose mutation in humans is linked to nonsyndromic congenital hydrocephalus (NSCH). DAPLE contains a PDZ-binding motif (PBM) and is also mutated in human NSCH, so we investigated the functional relationship between both proteins. DAPLE colocalized with MPDZ at apical cell junctions and bound directly to the PDZ3 domain of MPDZ via its PBM. Much like DAPLE, MPDZ is induced during neurulation in Xenopus and is required for apical constriction of neuroepithelial cells and subsequent neural plate bending. MPDZ depletion also blunted DAPLE-­mediated apical constriction of cultured cells. These results show that DAPLE and MPDZ, two factors genetically linked to NSCH, function as cooperative partners at apical junctions and are required for proper tissue remodeling during early stages of neurodevelopment.

OKP cells express the Na-dicarboxylate cotransporter NaDC-1

2004 ◽  
Vol 287 (1) ◽  
pp. C64-C72 ◽  
Author(s):  
Seiji Aruga ◽  
Ana M. Pajor ◽  
Kiyoshi Nakamura ◽  
Liping Liu ◽  
Orson W. Moe ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Xenopus Oocytes ◽  
Fluorescent Protein ◽  
Stone Formation ◽  
Chronic Metabolic Acidosis ◽  
Opossum Kidney ◽  
Citrate Transport ◽  
Increased Risk ◽  
Green Fluorescent ◽  
Urinary Citrate

Urinary citrate concentration, a major factor in the formation of kidney stones, is primarily determined by its rate of reabsorption in the proximal tubule. Citrate reabsorption is mediated by the Na-dicarboxylate cotransporter-1 (NaDC-1). The opossum kidney (OKP) cell line possesses many characteristics of the renal proximal tubule. The OKP NaDC-1 (oNaDC-1) cDNA was cloned and encodes a 2.4-kb mRNA. When injected into Xenopus oocytes, the cotransporter is expressed and demonstrates Na-coupled citrate transport with a stoichiometry of ≥3 Na:1 citrate, specificity for di- and tricarboxylates, pH-dependent citrate transport, and pH-independent succinate transport, all characteristics of the other NaDC-1 orthologs. Chronic metabolic acidosis increases proximal tubule citrate reabsorption, leading to profound hypocitraturia and an increased risk for stone formation. Under the conditions studied, endogenous OKP NaDC-1 mRNA abundance is not regulated by changes in media pH. In OKP cells transfected with a green fluorescent protein-oNaDC-1 construct, however, media acidification increases Na-dependent citrate uptake, demonstrating posttranscriptional acid regulation of NaDC-1 activity.

scholarly journals LKB1, a novel serine/threonine protein kinase and potential tumour suppressor, is phosphorylated by cAMP-dependent protein kinase (PKA) and prenylated in vivo

2000 ◽  
Vol 345 (3) ◽  
pp. 673-680 ◽  
Author(s):  
Sean P. COLLINS ◽  
Junewai L. REOMA ◽  
David M. GAMM ◽  
Michael D. UHLER
Keyword(s):  
Protein Kinase ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Phosphorylation Site ◽  
Multiple Cancer ◽  
Dependent Protein Kinase ◽  
Rnase Protection ◽  
Camp Dependent Protein Kinase ◽  
Increased Risk ◽  
Dependent Protein

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disease characterized by melanocytic macules, hamartomatous polyps and an increased risk for numerous cancers. The human LKB1 (hLKB1) gene encodes a serine/threonine protein kinase that is deficient in the majority of patients with PJS. The murine LKB1 (mLKB1) cDNA was isolated, sequenced and shown to produce a 2.4-kb transcript encoding a 436 amino acid protein with 90% identity with hLKB1. RNA blot and RNase-protection analysis revealed that mLKB1 mRNA is expressed in all tissues and cell lines examined. The widespread expression of LKB1 transcripts is consistent with the elevated risk of multiple cancer types in PJS patients. The predicted LKB1 protein sequence terminates with a conserved prenylation motif (Cys433-Lys-Gln-Gln436) directly downstream from a consensus cAMP-dependent protein kinase (PKA) phosphorylation site (Arg428-Arg-Leu-Ser431). The expression of enhanced green fluorescent protein (EGFP)-mLKB1 chimaeras demonstrated that LKB1 possesses a functional prenylation motif that is capable of targeting EGFP to cellular membranes. Mutation of Cys433 to an alanine residue, but not phosphorylation by PKA, blocked membrane localization. These findings suggest that PKA does phosphorylate LKB1, although this phosphorylation does not alter the cellular localization of LKB1.

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