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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relationship between cell membrane polarity and calcium oxalate (CaOx) crystal binding was studied in rat renal inner medullary collecting duct (IMCD) cells in primary culture. Cultures grew as simple monolayers (M) with interspersed cellular aggregates (A), and CaOx bound preferentially to A. An antibody that recognizes an exclusively basolateral epitope in intact IMCD binds to some of the cells in A but not to cells in M. Lysing of intercellular junctions with 3 mM EGTA (monitored by transepithelial resistance, R) resulted in basolateral antibody binding to the previously negative cells in M and a 21-fold increase in CaOx adherence to M over control (P less than 0.01). Enhanced CaOx attachment appeared to lag behind the fall in R by 5-10 min. Crystal attachment returned to control between 30 and 120 min after removal of EGTA and readdition of Ca. These data suggest that loss of epithelial membrane polarity may result in enhanced capacity to bind CaOx. Such loss of cell membrane polarity may occur in IMCD with some forms of epithelial injury and repair and may provide a site of crystal fixation to initiate nephrolithiasis.
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PMID:Cell polarity and calcium oxalate crystal adherence to cultured collecting duct cells. 153 82

Calcium oxalate (CaOx) urolithiasis in rats is induced by producing hyperoxaluria. Depending on the degree and length of hyperoxaluria, CaOx crystals may either form in the nephron or the bladder and may or may not be retained in the kidneys. Crystals may nucleate in one part of the nephron and be retained in another part. Papillary collecting duct tubular epithelium and its basement membrane appear to be involved in crystal retention in the kidneys.
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PMID:Pathogenesis of oxalate urolithiasis: lessons from experimental studies with rats. 200 7

Attachment of microcrystals to cellular membranes may be an important component in the pathophysiology of urolithiasis. This study characterizes the concentration-dependent binding of uric acid crystals to rat renal inner medullary collecting duct cells in primary culture. Collecting duct cell cultures grew as monolayers with interspersed aggregates of rounded cells. Cultures were incubated with 14C-uric acid crystals, and the crystals that bound were quantitated by adherent radioactivity. Uric acid crystal adherence demonstrated concentration dependent saturation with a 1/alpha value (maximum micrograms of crystals adhering to 1 cm2 of binding area) of 645 micrograms/cm2. The beta values (fraction of cross-sectional area which bound crystals) of uric acid (mean = 0.15) and calcium oxalate monohydrate (mean = 0.13) crystals did not differ significantly. Uric acid crystal binding was inhibited by pre-bound calcium oxalate monohydrate crystals in a concentration dependent manner. These data suggest that uric acid and calcium oxalate crystals exhibit similar binding patterns to rat renal inner medullary collecting duct cells in primary culture.
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PMID:Uric acid crystal binding to renal inner medullary collecting duct cells in primary culture. 210 62

The interaction between renal epithelial cells and calcium oxalate (CaOx) crystals and/or oxalate ions plays a critical role in the formation of urinary stones. Epithelial cells respond to hyperoxaluria and the presence of CaOx crystals in the kidneys by increased enzymuria and internalization of the crystals. Crystal cell interaction results in movement of crystals from the luminal to the basolateral side between the cells and the basement membrane. Once beneath the epithelium, crystals adhere to the basement membrane and become anchored inside the kidneys. Crystals anchored to basement membrane of the peripheral collecting duct aggregate with other crystals and move through an eroding epithelium to the papillary surface, furnishing an encrustation platform or a nidus for future development of a kidney stone. Thus interaction between renal epithelial cells and CaOx crystals and/or oxalate ions is an essential element in the development of urinary stone disease.
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PMID:Calcium oxalate crystal interaction with renal tubular epithelium, mechanism of crystal adhesion and its impact on stone development. 767 37

Urolithiasis is a multifaceted process that initiates with the formation of microcrystals in the urine and terminates with the formation of mature renal calculi. The attachment of crystals by the urothelium is a major event in the successful formation of the mature stone. The papillary tip is the primary site for crystal attachment and stone maturation, and the attachment process appears to be mediated by specific molecular interactions between molecular structures on the surfaces of stone crystals and molecular arrays on the surfaces of cell membranes. Animal models have demonstrated the interaction between cells and crystals, and they have suggested a correlation between cellular damage and crystal interaction, especially when crystals bind to and then break free from the tubular epithelium. Cell culture studies on inner medullary late collecting duct (IMCD) cells have demonstrated that calcium oxalate monohydrate, hydroxyapatite, and uric acid crystals bind to IMCD cells in primary culture. The attachment of these crystals to IMCD cells was crystal structure dependent, saturable, and competitively inhibitable if more than one crystal type was present at the same time. The crystals preferentially attach to cells that have lost partial or complete intercellular junctional integrity. These crystal-attaching cells appear to have altered membrane composition and/or structure. Recent studies on red blood cells and IMCD cells that have been enriched with cholesterol and selected phospholipids suggest that crystal-membrane phospholipid interactions play a major role in crystal attachment.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Crystal-membrane interaction in kidney stone disease. 787 43

The development of urolithiasis is a multifaceted process, starting at urine supersaturation and ending with the formation of mature renal calculi. The retention of microcrystals by the urothelial cell membrane is a critical event in the process. The current study examines calcium oxalate monohydrate (COM) crystal attachment to inner medullary collecting duct (IMCD) cells following selective changes in cell membrane phospholipid composition. Both primary culture of IMCD cells and a continuous IMCD cell line were used for these studies. Cell membrane composition was selectively altered by either exogenous addition of membrane phospholipids or using membrane lipid scrambling agents. Enrichment with anionic phospholipids was found to greatly increase attachment of crystals to the cells. This increased attachment correlated with the exposure of phosphatidylserine (PS) on the exofacial leaflet of the cell membrane as demonstrated by the use of the membrane scrambling agent A-23187. Furthermore, the increased COM attachment following PS exposure could be blocked by incubating the cells with the PS-specific binding protein, annexin V. These results support the hypothesis that exposure of PS head groups on the papillary epithelial cell surface may mediate stone crystal attachment to the kidney tubule cell epithelium in the renal papilla, possibly as an initiating event in urolithiasis.
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PMID:Surface exposure of phosphatidylserine increases calcium oxalate crystal attachment to IMCD cells. 903 49

The development of urolithiasis is a multifaceted process, starting with urine supersaturation and ending with the formation of mature renal calculi. The retention of microcrystals by kidney tubule epithelium cell membranes has been proposed as a critical event in the process. To date, attachment of kidney stone constituent crystals to urothelial cells has been demonstrated both in vitro and in vivo yet the mechanism of crystal attachment remains unknown. We hypothesize that for effective stone crystal attachment to the epithelium there must be cell membrane rearrangement that would allow for long-range bonding between the stone crystal and the cell membrane. This rearrangement may be influenced by the physical state of the membrane. The current study examines calcium oxalate monohydrate (COM) crystal attachment to inner medullary collecting duct (IMCD) cells following changes in cell membrane fluidity. Radioactively labeled COM crystals were used to quantitate crystal attachment. Membrane fluidity was altered by changing temperature, cell membrane cholesterol content, or extended length of cell culture. Crystal attachment to IMCD cells was directly correlated to changes in membrane fluidity. This finding was consistently observed regardless of the method used to alter membrane fluidity. The results are consistent with the theory that the ability to form a crystal attachment region on the cell surface may be related to the ease of rearrangement of membrane components at the cell surface. Variations in the urothelial cell environment during certain pathological conditions in the kidney could induce these physical perturbations and prime kidney epithelial cells at or near the papillary tip to bind COM crystals.
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PMID:The dependence on membrane fluidity of calcium oxalate crystal attachment to IMCD membranes. 907 36

A model is presented visualizing the events leading to calcium-salt, crystal- and stone-formation inside the nephron. For each nephron segment, handling of urine components relevant to stone formation is considered and urine composition determined. This information was applied to nucleation experiments simulating passage of urine through a nephron. The model and in vitro experiments suggest that within normal transit times for the respective nephron segments, particles of a hydroxyapatite-like material first form near the bend in the Loop of Henle of juxtamedullary nephrons. From there on, calcium oxalate particles start to appear: first dihydrate, then monohydrate. In the collecting duct system, particle size increases primarily due to crystal agglomeration. Several conclusions with clinical and experimental relevance can be drawn. An increase in urinary volume does not decrease the chance of crystal formation in the Loop of Henle, but does decrease passage time through the collecting ducts, and thus, the time allowed for large particle formation. A calcium load does not increase the risk for nucleation up to the distal tubule, but does increase the risk of large particle formation in the collecting ducts. An oxalate load increases the chance for nucleation throughout the nephron. For experiments simulating crystallization processes occurring inside the nephron, diluted urines should be used. They should be diluted 16 to 50 times for testing nucleation, 2 to 30 times for testing crystal growth, and 2 to 20 times for testing crystal agglomeration. Undiluted urines may be used to mimic conditions in the pelvis and the bladder.
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PMID:Crystallization and stone formation inside the nephron. 981 25

Calcium stone crystal attachment to the urinary epithelium plays an essential role in the development of kidney stones by allowing small crystals to be retained in the kidney until they become macroscopic. We among others have described attachment of stone crystals to cultured renal epithelia (Wiessner, J. H., Kleinman, J. G., Blumenthal, S. S., Garancis, J. C., and Mandel, G. S. (1987) J. Urol. 138, 640-643). To isolate protein(s) that may participate in crystal attachment, apical membranes of cultured renal inner medullary collecting duct were biotinylated, the cells were lysed with detergent, the lysate was subjected to hydroxyapatite chromatography, and fractions were incubated with calcium oxalate monohydrate. Electrophoresis of material solubilized from the crystals showed several selectively adsorbed protein bands. A 110-kDa band stained positively for biotin and for glycosides and bound (45)Ca. The amino acid sequence of this band was determined to be that of a protein closely related to rat nucleolin (nucleolin-related protein; NRP). NRP was cloned and sequenced and was 83% homologous with the previously sequenced nucleolar protein nucleolin. Using temperature-induced phase partitioning with Triton X-114, NRP was associated with both the insoluble membrane skeleton pellet and the soluble aqueous phase but not the soluble detergent phase. This association with the membrane skeleton was increased in the presence of calcium. Thus, NRP is associated with the apical membranes of cultured renal tubular cells and is bound to membrane skeletal elements in a calcium-dependent fashion. The physiological role of NRP remains to be determined; however, a pathophysiological role may be that of mediating the attachment to the renal tubular epithelium of calcium stone crystals.
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PMID:Cloning and preliminary characterization of a calcium-binding protein closely related to nucleolin on the apical surface of inner medullary collecting duct cells. 1048 83

A molecular mechanism of crystal attachment to renal cells after injury has been proposed in which the exposure of phosphatidylserine (PS) on the cell membrane surface following injury provides attachment sites for calcium-containing crystals. Annexin V was used to determine whether injury to kidney cells by oxalate in culture resulted in PS exposure on the cell surface. When continuous cultures of intermedullary collecting duct cells were exposed to various levels of oxalate, a dose-dependent increase in PS exposure was observed on the cell surfaces. Initially, only scattered cells expressed PS on the surface. However, as the level of oxalate increased, groups of cells began to express PS, suggesting that the injured cells may have an influence on neighboring cells. Exposure of PS on the cell membrane surface correlated with a corresponding increase in calcium oxalate monohydrate crystal attachment to the cells. This indicates that damage to kidney epithelial cells by elevated concentrations of urinary components, in this case oxalate, could result in exposure of PS on cells, which could provide a point of fixation or nucleation for calcium-containing crystals.
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PMID:Oxalate-induced exposure of phosphatidylserine on the surface of renal epithelial cells in culture. 1054 Dec 80


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