Phosphorylation of slit diaphragm proteins NEPHRIN and NEPH1 upon binding of HGF promotes podocyte repair

The spatial characteristics of the erosion laser plasma are investigated. The application of small-sized spectrometers of the visible and ultraviolet ranges for recording the spectrum of plasma radiation is considered. Erosive laser plasma is formed on the surface of a silicon target under the action of pulsed laser radiation with a wavelength of 1064 nm under normal atmospheric conditions. The laser plasma torch was scanned using a movable slit diaphragm oriented parallel to the target surface. The emission of erosion laser plasma was recorded using small-size spectrometers. Based on the obtained plasma emission spectra, the dependences of the intensity of the spectral lines of silicon on the geometric position of the slit diaphragm are revealed. A comparison is made of the intensities of the spectral lines of silicon on the polished and grinded sides of the target.

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The Short-Term Effects of C-Peptide on the Early Diabetes-Related Ultrastructural Changes to the Podocyte Slit Diaphragm of Glomeruli in Rats

Microcirculation ◽

10.1111/micc.12185 ◽

2015 ◽

Vol 22 (2) ◽

pp. 122-132 ◽

Cited By ~ 3

Author(s):

Hiroshi Nakamoto ◽

Kazuhiko Nakayama ◽

Noriaki Emoto ◽

Fumihiko Kajiya

Keyword(s):

Slit Diaphragm ◽

Ultrastructural Changes ◽

Short Term ◽

Early Diabetes ◽

C Peptide ◽

Short Term Effects

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The tight junction protein ZO-1 is concentrated along slit diaphragms of the glomerular epithelium.

The Journal of Cell Biology ◽

10.1083/jcb.111.3.1255 ◽

1990 ◽

Vol 111 (3) ◽

pp. 1255-1263 ◽

Cited By ~ 197

Author(s):

E Schnabel ◽

J M Anderson ◽

M G Farquhar

Keyword(s):

Tight Junction ◽

Rat Kidney ◽

Freeze Fracture ◽

Kidney Tissue ◽

Slit Diaphragm ◽

Kidney Cortex ◽

Adult Rats ◽

Junction Protein ◽

Collecting Tubules ◽

Lateral Cell

The foot processes of glomerular epithelial cells of the mammalian kidney are firmly attached to one another by shallow intercellular junctions or slit diaphragms of unknown composition. We have investigated the molecular nature of these junctions using an antibody that recognizes ZO-1, a protein that is specific for the tight junction or zonula occludens. By immunoblotting the affinity purified anti-ZO-1 IgG recognizes a single 225-kD band in kidney cortex and in slit diaphragm-enriched fractions as in other tissues. When ZO-1 was localized by immunofluorescence in kidney tissue of adult rats, the protein was detected in epithelia of all segments of the nephron, but the glomerular epithelium was much more intensely stained than any other epithelium. Among tubule epithelia the signal for ZO-1 correlated with the known fibril content and physiologic tightness of the junctions, i.e., it was highest in distal and collecting tubules and lowest in the proximal tubule. By immunoelectron microscopy ZO-1 was found to be concentrated on the cytoplasmic surface of the tight junctional membrane. Within the glomerulus ZO-1 was localized predominantly in the epithelial foot processes where it was concentrated precisely at the points of insertion of the slit diaphragms into the lateral cell membrane. Its distribution appeared to be continuous along the continuous slit membrane junction. When ZO-1 was localized in differentiating glomeruli in the newborn rat kidney, it was present early in development when the apical junctional complexes between presumptive podocytes are composed of typical tight and adhering junctions. It remained associated with these junctions during the time they migrate down the lateral cell surface, disappear and are replaced by slit diaphragms. The distribution of ZO-1 and the close developmental relationship between the two junctions suggest that the slit diaphragm is a variant of the tight junction that shares with it at least one structural protein and the functional property of defining distinctive plasmalemmal domains. The glomerular epithelium is unique among renal epithelia in that ZO-1 is present, but the intercellular spaces are wide open and no fibrils are seen by freeze fracture. The presence of ZO-1 along slit membranes indicates that expression of ZO-1 alone does not lead to tight junction assembly.

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Treatment with irbesatan may improve slit diaphragm alterations in rats with adriamycin-induced nephropathy

Journal of the Renin-Angiotensin-Aldosterone System ◽

10.1177/1470320316646884 ◽

2016 ◽

Vol 17 (2) ◽

pp. 147032031664688 ◽

Cited By ~ 3

Author(s):

Na Wang ◽

Ri-bao Wei ◽

Ping Li ◽

Qing-ping Li ◽

Xi Yang ◽

...

Keyword(s):

Slit Diaphragm

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PI(4,5)P2 controls slit diaphragm formation and endocytosis in Drosophila nephrocytes

10.1101/2021.06.22.449474 ◽

2021 ◽

Author(s):

Max Gass ◽

Sarah Borkowsky ◽

Marie-Luise Lotz ◽

Rita Schroeter ◽

Pavel Nedvetsky ◽

...

Keyword(s):

Plasma Membrane ◽

Model System ◽

Dominant Negative ◽

Slit Diaphragm ◽

Phosphatidylinositol 3 Kinase ◽

Ectopic Activation ◽

Phosphatidylinositol 4 ◽

Asymmetrically Distributed ◽

Phosphatidylinositol 3

Drosophila nephrocytes are an emerging model system for mammalian podocytes and podocyte-associated diseases. Like podocytes, nephrocytes exhibit characteristics of epithelial cells, but the role of phospholipids in polarization of these cells is yet unclear. In epithelia phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) and phosphatidylinositol(3,4,5)-trisphosphate (PI(3,4,5)P3) are asymmetrically distributed in the plasma membrane and determine apical-basal polarity. Here we demonstrate that both phospholipids are present in the plasma membrane of nephrocytes, but only PI(4,5)P2 accumulates at slit diaphragms. Knockdown of Skittles, a phosphatidylinositol(4)phosphate 5-kinase, which produces PI(4,5)P2, abolished slit diaphragm formation and led to strongly reduced endocytosis. Notably, reduction in PI(3,4,5)P3 by overexpression of PTEN or expression of a dominant-negative phosphatidylinositol-3-Kinase did not affect nephrocyte function, whereas enhanced formation of PI(3,4,5)P3 by constitutively active phosphatidylinositol-3-Kinase resulted in strong slit diaphragm and endocytosis defects by ectopic activation of the Akt/mTOR pathway. Thus, PI(4,5)P2 but not PI(3,4,5)P3 is essential for slit diaphragm formation and nephrocyte function. However, PI(3,4,5)P3 has to be tightly controlled to ensure nephrocyte development.

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Crumbs2 Is an Essential Slit Diaphragm Protein of the Renal Filtration Barrier

Journal of the American Society of Nephrology ◽

10.1681/asn.2020040501 ◽

2021 ◽

pp. ASN.2020040501

Author(s):

Annika Möller-Kerutt ◽

Juan E. Rodriguez-Gatica ◽

Karin Wacker ◽

Rohan Bhatia ◽

Jan-Peter Siebrasse ◽

...

Keyword(s):

Er Stress ◽

Fluorescent Protein ◽

Glycosylation Site ◽

Slit Diaphragm ◽

Glycosylation Pattern ◽

Steroid Resistant ◽

Steroid Resistant Nephrotic Syndrome ◽

Er Stress Response ◽

Filtration Barrier ◽

Protein Variants

BackgroundCrumbs2 is expressed at embryonic stages as well as in the retina, brain, and glomerular podocytes. Recent studies identifiedCRB2mutations as a novel cause of steroid-resistant nephrotic syndrome (SRNS).MethodsTo study the function of Crb2 at the renal filtration barrier, mice lacking Crb2 exclusively in podocytes were generated. Gene expression and histologic studies as well as transmission and scanning electron microscopy were used to analyze theseCrb2podKOknockout mice and their littermate controls. Furthermore, high-resolution expansion microscopy was used to investigate Crb2 distribution in murine glomeruli. For pull-down experiments, live cell imaging, and transcriptome analyses, cell lines were applied that inducibly express fluorescent protein–tagged CRB2 wild type and mutants.ResultsCrb2podKOmice developed proteinuria directly after birth that preceded a prominent development of disordered and effaced foot processes, upregulation of renal injury and inflammatory markers, and glomerulosclerosis. Pull-down assays revealed an interaction of CRB2 with Nephrin, mediated by their extracellular domains. Expansion microscopy showed that in mice glomeruli, Crb2 and Nephrin are organized in adjacent clusters. SRNS-associated CRB2 protein variants and a mutant that lacks a putative conservedO-glycosylation site were not transported to the cell surface. Instead, mutants accumulated in the ER, showed altered glycosylation pattern, and triggered an ER stress response.ConclusionsCrb2 is an essential component of the podocyte’s slit diaphragm, interacting with Nephrin. Loss of slit diaphragm targeting and increasing ER stress are pivotal factors for onset and progression of CRB2-related SRNS.

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