Phosphorylation of Nephrin Triggers Its Internalization by Raft-Mediated Endocytosis

Qin, Xiaosong; Tsukaguchi, Hiroyasu; Shono, Atsuko; Yamamoto, Akira; Kurihara, Hidetake; Doi, Toshio

doi:10.1681/asn.2009010011

Cited by 82 publications

(103 citation statements)

References 44 publications

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“…In accordance with our results, the role of PKC␣ in diabetic nephrin endocytosis was confirmed very recently by Tossidou et al (33). It has been recently reported that nephrin traffics via raft-or clathrin-mediated endocytosis (34). From other receptors, it is known that ␤-arrestin2-dependent endocytosis mainly utilizes the clathrin pathway.…”

Section: Discussionsupporting

confidence: 92%

PKCα Mediates β-Arrestin2-dependent Nephrin Endocytosis in Hyperglycemia

Quack

Woznowski

Potthoff

et al. 2011

Journal of Biological Chemistry

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Nephrin, the key molecule of the glomerular slit diaphragm, is expressed on the surface of podocytes and is critical in preventing albuminuria. In diabetes, hyperglycemia leads to the loss of surface expression of nephrin and causes albuminuria. Here, we report a mechanism that can explain this phenomenon: hyperglycemia directly enhances the rate of nephrin endocytosis via regulation of the ␤-arrestin2-nephrin interaction by PKC␣. We identified PKC␣ and protein interacting with c kinase-1 (PICK1) as nephrin-binding proteins. Hyperglycemia induced up-regulation of PKC␣ and led to the formation of a complex of nephrin, PKC␣, PICK1, and ␤-arrestin2 in vitro and in vivo. Binding of ␤-arrestin2 to the nephrin intracellular domain depended on phosphorylation of nephrin threonine residues 1120 and 1125 by PKC␣. Further, cellular knockdown of PKC␣ and/or PICK1 attenuated the nephrin-␤-arrestin2 interaction and abrogated the amplifying effect of high blood glucose on nephrin endocytosis. In C57BL/6 mice, hyperglycemia over 24 h caused a significant increase in urinary albumin excretion, supporting the concept of the rapid impact of hyperglycemia on glomerular permselectivity. In summary, we have provided a molecular model of hyperglycemia-induced nephrin endocytosis and subsequent proteinuria and highlighted PKC␣ and PICK1 as promising therapeutic targets for diabetic nephropathy.Diabetes mellitus is a major health problem in Western countries. Despite therapeutic advances, diabetic nephropathy remains the leading cause of end stage renal disease (1). Chronic hyperglycemia causes glomerular damages such as endothelial dysfunction, loss of negative charges in the basement membrane, and podocyte damage (2). Microalbuminuria is an early symptom of a "leaky" glomerular barrier and is associated with a markedly increased cardiovascular risk (3).Podocytes are visceral epithelial cells wrapped around glomerular capillaries and are connected by the slit diaphragm. This specialized cell junction is a dynamic multiprotein complex that functions as a size-selective sieve to prevent the loss of plasma proteins through urine (4, 5). Nephrin serves as the backbone of this diaphragm by functioning as a regulator of podocyte signaling and mediator of actin dynamics (6 -8). Several podocyte signaling abnormalities have been noted in diabetes. For example, mice and humans with diabetes show altered distribution and expression of nephrin (9 -11), and hyperglycemia increases diacylglycerol generation, causing PKC activation (2). However, it is not fully understood how "hyperglycemic" signaling in diabetes affects the expression and distribution of nephrin.Menne et al. (12) reported a major step elucidating podocyte signaling in diabetes: they showed that albuminuria does not develop in diabetic PKC␣-deficient mice and concluded that decreased nephrin expression in diabetes is a result of altered transcriptional regulation. All of the studies until now were conducted in chronic models of diabetes (13). Therefore, their conclusions were based...

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Section: Discussionsupporting

confidence: 92%

PKCα Mediates β-Arrestin2-dependent Nephrin Endocytosis in Hyperglycemia

Quack

Woznowski

Potthoff

et al. 2011

Journal of Biological Chemistry

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“…24 Nephrin, a structural component BASIC RESEARCH www.jasn.org of the glomerular slit diaphragm, is a single transmembranespanning receptor and also undergoes endocytosis, which affects slit diaphragm integrity. 22,25,26 In this study, reduction and altered staining patterns of nephrin and podocin would be due to a general defect in a secretory system as a cause of the podocyte disorder. Accumulation of intracellular vesicles in podocytes clearly argues into this direction and does not imply a specific defect in trafficking of slit-diaphragm proteins as a cause of the disease.…”

Section: Discussionmentioning

confidence: 78%

Prorenin Receptor Is Essential for Normal Podocyte Structure and Function

Ōshima¹,

Kinouchi

Ichihara

et al. 2011

Journal of the American Society of Nephrology

159

133

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The prorenin receptor is an accessory subunit of the vacuolar H ϩ -ATPase, suggesting that it has fundamental functions beyond activation of the local renin-angiotensin system. Podocytes express the prorenin receptor, but its function in these cells is unknown. Here, podocyte-specific, conditional, prorenin receptor-knockout mice died of kidney failure and severe proteinuria within 4 weeks of birth. The podocytes of these mice exhibited foot process effacement with reduced and altered localization of the slit-diaphragm proteins nephrin and podocin. Furthermore, the podocytes contained numerous autophagic vacuoles, confirmed by enhanced accumulation of microtubule-associated protein 1 light chain 3-positive intracellular vesicles. Ablation of the prorenin receptor selectively suppressed expression of the V 0 c-subunit of the vacuolar H ϩ -ATPase in podocytes, resulting in deacidification of intracellular vesicles. In conclusion, the prorenin receptor is important for the maintenance of normal podocyte structure and function.

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“…Quack et al demonstrated that threonine phosphorylation of nephrin triggers recruitment of ␤-arrestin-2, an adaptor protein known to mediate endocytosis of G protein-coupled receptors (26), which induces nephrin endocytosis (27). Nephrin internalization was also shown to occur via CIN85-mediated ubiquitination (28) and raft-mediated endocytosis (29). So far, disturbances of nephrin endocytosis have been implicated in the context of disease states, for example in high glucose-mediated podocyte injury (27).…”

mentioning

confidence: 99%

Planar Cell Polarity Pathway Regulates Nephrin Endocytosis in Developing Podocytes

Babayeva

Rocque

Aoudjit

et al. 2013

Journal of Biological Chemistry

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Background:The PCP pathway controls many cell processes during development. Results: The PCP pathway induces nephrin endocytosis when cultured podocytes are treated with Wnt5a. Loss of PCP protein Vangl2 decreases nephrin endocytosis. Conclusion: During glomerular development, endocytosis of nephrin is regulated by the PCP pathway. Significance: Implicating the PCP pathway in nephrin endocytosis is important for understanding the complexity of PCP signaling during mammalian development.

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Phosphorylation of Nephrin Triggers Its Internalization by Raft-Mediated Endocytosis

Cited by 82 publications

References 44 publications

PKCα Mediates β-Arrestin2-dependent Nephrin Endocytosis in Hyperglycemia

PKCα Mediates β-Arrestin2-dependent Nephrin Endocytosis in Hyperglycemia

Prorenin Receptor Is Essential for Normal Podocyte Structure and Function

Planar Cell Polarity Pathway Regulates Nephrin Endocytosis in Developing Podocytes

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