N-Linked Glycosylation Is Critical for the Plasma Membrane Localization of Nephrin

Kou, Yan; Khoshnoodi, Jamshid; Ruotsalainen, Vesa; Tryggvason, Karl

doi:10.1097/01.asn.0000013297.11876.5b

Cited by 87 publications

(102 citation statements)

References 20 publications

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“…Thus MDCKnephrin cells provide a valuable alternative to working with isolated glomeruli or conditionally immortalized podocytes for investigating the interactions of nephrin. Immortalized podocytes have the limitation that nephrin expression is low 59 or ceases on extended passaging. 40 Furthermore, podocyte cell lines do not form continuous monolayers with distinct apical and basolateral domains.…”

Section: Discussionmentioning

confidence: 99%

Nephrin Forms a Complex with Adherens Junction Proteins and CASK in Podocytes and in Madin-Darby Canine Kidney Cells Expressing Nephrin

Lehtonen

Kudlicka

Holthöfer

et al. 2004

The American Journal of Pathology

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Section: Discussionmentioning

confidence: 99%

Nephrin Forms a Complex with Adherens Junction Proteins and CASK in Podocytes and in Madin-Darby Canine Kidney Cells Expressing Nephrin

Lehtonen

Kudlicka

Holthöfer

et al. 2004

The American Journal of Pathology

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“…9,14,15 The following antibodies were purchased from the suppliers as indicated: anti-phospho-S6 ribosomal protein (S6RP) (Ser235/236) rabbit monoclonal, anti-S6RP rabbit monoclonal (5G10), anti-phospho-p70S6K (Thr389) rabbit polyclonal, anti-p70S6K rabbit polyclonal, anti-phospho-4EBP1 (ser65) rabbit polyclonal, anti-4EBP1 rabbit polyclonal, anti-phospho-AMP-activated protein kinase a (AMPKa) (Thr172) rabbit monoclonal, anti-AMPKa rabbit polyclonal, anti-phospho-a-subunit of eukaryotic translation initiation factor 2a (eIF2a) (Ser51) rabbit monoclonal and anti-eIF2a mouse monoclonal (L57A5) (Cell Signaling Technology, Beverly, MA, USA); anti-phospho-AKT1 (Ser473) rabbit polyclonal (Rockland, Gilbertsville, PA, USA); anti-glucose-regulated protein 78 mouse monoclonal (Stressgen Biotechnologies, Victoria, Canada); anti-b-actin mouse monoclonal (Sigma, Tokyo, Japan); HRPlabeled goat anti-rabbit and anti-mouse immunoglobulins (Dako, Carpinteria, CA, USA); and Alexa Fluor 488-conjugated goat anti-rabbit IgG, Texas Red-X goat anti-mouse IgG (Molecular Probes, Eugene, OR, USA). PAN was purchased from Sigma.…”

Section: Materials and Methods Antibodies And Reagentsmentioning

confidence: 99%

“…9 Nephrin is a transmembrane glycoprotein that is produced by podocytes and is responsible for the permselective barrier of the glomerulus. 12, 13 We previously determined that nephrin trafficking to the plasma membrane required N-glycosylation in the ER 14 and showed that a lack of ATP induced the hypoglycosylation of nephrin and its retention in the ER, which coincided with a strong induction of GRP78. 15 Interestingly, glucocorticoids and the immunosuppressant mizoribine, which are commonly used to treat MCD, normalized the abnormal N-glycosylation and nephrin localization by restoring ATP levels.…”

mentioning

confidence: 98%

mTORC1 activation triggers the unfolded protein response in podocytes and leads to nephrotic syndrome

Ito

Nishibori

Itô

et al. 2011

Laboratory Investigation

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Although podocyte damage is known to be responsible for the development of minimal-change disease (MCD), the underlying mechanism remains to be elucidated. Previously, using a rat MCD model, we showed that endoplasmic reticulum (ER) stress in the podocytes was associated with the heavy proteinuric state and another group reported that a mammalian target of rapamycin complex 1 (mTORC1) inhibitor protected against proteinuria. In this study, which utilized a rat MCD model, a combination of immunohistochemistry, dual immunofluorescence and confocal microscopy, western blot analysis, and quantitative real-time RT-PCR revealed co-activation of the unfolded protein response (UPR), which was induced by ER stress, and mTORC1 in glomerular podocytes before the onset of proteinuria and downregulation of nephrin at the post-translational level at the onset of proteinuria. Podocyte culture experiments revealed that mTORC1 activation preceded the UPR that was associated with a marked decrease in the energy charge. The mTORC1 inhibitor everolimus completely inhibited proteinuria through a reduction in both mTORC1 and UPR activity and preserved nephrin expression in the glomerular podocytes. In conclusion, mTORC1 activation may perturb the regulatory system of energy metabolism primarily by promoting energy consumption and inducing the UPR, which underlie proteinuria in MCD.

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“…Nephrin is a large (1241-amino acid, 185-kD) transmembrane molecule with Ig-like domains. N-linked glycosylation is critical for the plasma membrane localization of nephrin (66). Its predicted structure and biochemical properties, as well as electron microscopy studies, suggested that nephrin may form dimers through homophilic interactions across the filtration slit (67).…”

Section: The Critical Role Of Nephrin In Maintaining the Glomerular Fmentioning

confidence: 99%

Podocyte Biology and Response to Injury

Mündel¹,

Shankland²

2002

Journal of the American Society of Nephrology

600

541

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The visceral glomerular epithelial cell, also called podocyte, is a terminally differentiated cell that lines the outer aspect of the glomerular basement membrane (GBM). It therefore forms the final barrier to protein loss, which explains why podocyte injury is typically associated with marked proteinuria. Indeed, all forms of nephrotic syndrome are characterized by abnormalities in the podocyte. In this review, we will provide an update of the known functions of recent podocyte-specific proteins and focus on the slit diaphragm (SD) and the mechanisms underlying foot process (FP) flattening and how the podocyte responds to injury. Molecular Anatomy of the Podocyte FP CytoskeletonPodocyte FP are not static, but rather contain a contractile system similar to that seen in pericytes. This contractile apparatus is composed of actin, myosin-II, ␣-actinin-4, talin, and vinculin (1). The actin filament bundles form arches between adjacent FP of the same podocyte (2). Figure 1 is a schema of our current understanding of the molecular composition of the cytoskeleton in podocyte FP. Importantly, the actin filaments are connected to the underlying GBM at focal contacts via an ␣3␤1 integrin complex (3,4). The bends of the actin filament arches appear to be connected directly to the microtubules of the major processes (own unpublished results). FP are anchored to the GBM via ␣3␤1 integrin (5) and dystroglycans (6,7). Neighboring FP are connected by a cell-cell junction, the glomerular SD, which represents the main size selective filter barrier in the kidney (8 -10). The SD is thought to be a modified adherens junction (11) that is composed of a growing number of proteins, including nephrin (12-14), P-cadherin, CD2AP (15-18), , FAT (20), podocin (16,21), and possibly Neph1 (see reference 22 and below). In addition to the contractile proteins described above, we have reported the association of synaptopodin with the actin filaments in FP (23). Synaptopodin is the first member of a novel class of prolinerich proteins (24) and, like ␣-actinin-4, interacts with the tight junction protein MAGI-1 (25) that is also expressed in podocytes (26). Four Major Causes of FP EffacementThe basolateral portion of the foot processes represents the center of podocyte function and is defined by three membrane domains: the apical membrane domain, the SD protein complex, and the basal membrane domain or sole plate (27). The submembranous regions of all compartments are connected to the FP actin cytoskeleton, e.g., on the apical membrane domain, podocalyxin associates with the actin cytoskeleton through interactions with ezrin and the actin cytoskeleton via Na ϩ /H ϩ -exchanger regulatory factor 2 (NHERF2), a scaffold protein containing two PDZ (PSD-95/Dlg/ZO-1) domains and an ERM-binding region (28,29). The FP actin cytoskeleton is highly dynamic and ultimately determines the structural maintenance of the filtration slits as demonstrated in the acute PS/heparin model by several groups (30 -32). Interference with one of the three domains eventually ...

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N-Linked Glycosylation Is Critical for the Plasma Membrane Localization of Nephrin

Cited by 87 publications

References 20 publications

Nephrin Forms a Complex with Adherens Junction Proteins and CASK in Podocytes and in Madin-Darby Canine Kidney Cells Expressing Nephrin

Nephrin Forms a Complex with Adherens Junction Proteins and CASK in Podocytes and in Madin-Darby Canine Kidney Cells Expressing Nephrin

mTORC1 activation triggers the unfolded protein response in podocytes and leads to nephrotic syndrome

Podocyte Biology and Response to Injury

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