Differential expression of collagen- and laminin-binding integrins mediates ureteric bud and inner medullary collecting duct cell tubulogenesis

Abstract

-Inner medullary collecting ducts (IMCD) are terminally differentiated structures derived from the ureteric bud (UB). UB development is mediated by changes in the temporal and spatial expression of integrins and their respective ligands. We demonstrate both in vivo and in vitro that the UB expresses predominantly laminin receptors (␣ 3␤1-, ␣6␤1-, and ␣ 6␤4-integrins), whereas the IMCD expresses both collagen (␣1␤1-and ␣ 2␤1-integrins) and laminin receptors. Cells derived from the IMCD, but not the UB, undergo tubulogenesis in collagen-I (CI) gels in an ␣1␤1-and ␣2␤1-dependent manner. UB cells transfected with the ␣ 2-integrin subunit undergo tubulogenesis in CI, suggesting that collagen receptors are required for branching morphogenesis in CI. In contrast, both UB and IMCD cells undergo tubulogenesis in CI/ Matrigel gels. UB cells primarily utilize ␣ 3␤1-and ␣6-integrins, whereas IMCD cells mainly employ ␣ 1␤1 for this process. These results demonstrate a switch in integrin expression from primarily laminin receptors in the early UB to both collagen and laminin receptors in the mature IMCD, which has functional consequences for branching morphogenesis in three-dimensional cell culture models. This suggests that temporal and spatial changes in integrin expression could help organize the pattern of branching morphogenesis of the developing collecting system in vivo. kidney development; branching morphogenesis; three-dimensional culture; basement membranes THE MULTIBRANCHED INNER MEDULLARY collecting ducts (IMCD) of the kidney are highly ordered, terminally differentiated structures consisting of polarized epithelial cells derived embryologically from the ureteric bud (UB). The UB, which originates as an outgrowth from the Wolffian duct, also gives rise to the ureters and the epithelial lining of the trigone of the bladder. For such diverse urogenital segments to develop from the UB, cells must undergo well-defined differentiation processes (15).The collecting system of the kidney is formed by iterative branching morphogenesis of the UB. Although this process has been studied in whole animal, organ, and cell culture models, the molecular cues for its control are still poorly understood. Cell culture models, which predominantly utilize Madin-Darby canine kidney (MDCK) cells grown in three-dimensional (3D) collagen-I (3D-CI) gels, recapitulate branching morphogenesis in its simplest form. These models suggest that branching morphogenesis is a multistep process that requires sequential cell adhesion to extracellular matrix (ECM), cell spreading, cell proliferation, and cell migration to ultimately form multicellular tubelike structures (14). A balance between proliferation and apoptosis is critical for the final formation of the lumen of the tubule (5).Integrins, the predominant cell-surface receptors that mediate interactions between cells and ECM, play a crucial role in cellular functions such as cell adhesion, migration, proliferation, and apoptosis (7, 21). Both in vivo and in vitro data demonstrate the importance...

Integrin α3β1, a Novel Receptor for α3(IV) Noncollagenous Domain and a Trans-dominant Inhibitor for Integrin αvβ3

“…Proliferation Assays-CT26 cells (5 ϫ 10 3 cells/well) were seeded into 96-well plates and treated with ␣3NC1 at various concentrations in Dulbecco's modified Eagle's medium supplemented with 2% fetal bovine serum and proliferation was measured using [ 3 H]thymidine incorporation as described (26). Solid Phase Ligand Binding Assays-Purified integrin ␣3␤1 (Chemicon) was coated on 96-well plates at 1 g/ml in TBS overnight at 4°C.…”

“…3A, R10 cells bound soluble ␣3NC1 domain at much higher levels than B10 cells. This difference is exclusively attributed to integrin ␣3␤1 since the levels of expression for other ␣␤1 and ␤4 integrins is similar in both cell populations (26). Furthermore the expression of integrins ␤3 and ␣v was similar in the two cell lines (2.19 Ϯ 0.58-fold versus 1.966 Ϯ 0.91-fold increase in fluorescence ␤3 integrin and 7.003 Ϯ 4.14 versus 4.89 Ϯ 2.42 for ␣v integrin in B10 and R10 cells, respectively).…”

“…Integrin ␣3-null cells from kidney papillae (B10) and integrin ␣3-null cells reconstituted with human ␣3 integrin (R10) have been characterized (18,26). As shown in Fig.…”

Strategies Targeting cAMP Signaling in the Treatment of Polycystic Kidney Disease

“…Laminin binding integrins (a3b1, a6b1, and a6b4) are expressed in the branching ureteric bud, whereas both laminin binding and collagen binding (a1b1 and a2b1) integrins are expressed in the differentiated collecting duct. 98,99 Their ligands laminin-511 (a5b1g1 or laminin 10) and laminin-332 (a3b3g2 or laminin-5) are also expressed in the ureteric bud and the differentiated collecting duct. 98,99 Integrin b4 and -b1 are overexpressed in cyst cells and may mediate their increased adhesion to laminin-322 and collagen, respectively, which are also overexpressed.…”

Mxi1 influences cyst formation in three-dimensional cell culture

“…The collecting system of the kidney is formed by iterative branching morphogenesis of the ureteric bud. Although this process has been studied in whole animal, organ, and cell culture models, the molecular cues for its control are still poorly understood (4). Especially, three-dimensional (3-D) cell culture is similar to the in vivo system in cell shape and cellular environments, and is a powerful cystogenetic method to study the epithelial architecture that is specifically involved with molecular signals.…”