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Naoko Miyauchi

Publications and source records attributed to Naoko Miyauchi.

7 recordsLinked to original sources
PubMed2006

Synaptic vesicle protein 2B is expressed in podocyte, and its expression is altered in proteinuric glomeruli.

Synaptic vesicle protein 2B (SV2B) was identified by the subtraction hybridization technique as a molecule of which mRNA expression was decreased in puromycin aminonucleoside (PAN) nephropathy by glomerular cDNA subtraction assay. The expression of SV2B was detected in glomerular lysate with Western blot analysis. Dual-labeling immunofluorescence studies with glomerular cell markers demonstrated that SV2B is expressed in glomerular visceral epithelial cells (podocytes). The expression of SV2B is detected also in cultured podocyte and in human kidney section as podocytic pattern. The decrease of SV2B mRNA was already detected before the onset of proteinuria in PAN nephropathy. The mRNA expression of SV2B clearly is altered not only in PAN nephropathy but also in another proteinuric state that is caused by an antibody against nephrin, a functional molecule of the slit diaphragm. The decreased intensity in SV2B staining was already detected before the peak of proteinuria in both models with immunofluorescence study. A reduced amount of SV2B was detected in both models also with Western blot analysis. CD2AP, another functional molecule of the slit diaphragm, was observed in cytoplasm, including the processes area of the cultured podocyte, and when the podocyte was treated with small interfering RNA for SV2B, CD2AP staining at the process area was not detected. These results suggest that SV2B is a functional molecule of podocyte, and SV2B may play a role in the expression and proper localization of CD2AP.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Role of podocyte slit diaphragm as a filtration barrier.

Although the role of glomerular basement membrane has been emphasised as the barrier for retaining plasma proteins in the past three decades, some recent studies have demonstrated that the slit diaphragm of the glomerular epithelial cell (podocyte) is the structure likely to be the barrier in the glomerular capillary wall. Nephrin and podocin were identified as gene products mutated in Finnish-type congenital nephrotic syndrome and autosomal recessive steroid-resistant nephrotic syndrome, respectively. Nephrin s located at the outer leaflet of plasma membranes of the slit diaphragm. Podocin is reported to have an interaction with nephrin. The anti-nephrin antibody is capable of inducing massive proteinuria, which indicates that nephrin is a key functional molecule in the slit diaphragm. The expression of nephrin and podocin was reduced in glomeruli of minimal change nephrotic syndrome, which suggested that the altered expression of these molecules contributes to the development of proteinuria also in acquired diseases. Some recent studies demonstrated that CD2-associated protein (CD2AP) is also a functional molecule in the slit diaphragm, and its expression is altered in membranous nephropathy. These observations suggested that alteration of the molecular arrangement in the slit diaphragm is involved in the development of proteinuria in several kinds of glomerular diseases.

Animals↗
PubMed2005

Altered expression of junctional adhesion molecule 4 in injured podocytes.

Recent investigations have revealed the importance of glomerular podocytes with its diaphragm as the major filtration barrier. Junctional adhesion molecule 4 (JAM4) has been identified as a protein that interacts with membrane-associated guanyl kinase inverted (MAGI)-1 and is reported to be expressed on podocytes. To elucidate the role of JAM4 on podocytes, we examined the expression of JAM4 and MAGI-1 in normal and two different proteinuric rat models: puromycin aminonucleoside (PAN) nephropathy and anti-nephrin antibody-induced (ANA) nephropathy, one model with and one without effacement of podocyte foot processes. JAM4 was detected by immunomicroscopy at the apical membrane of normal podocytes. JAM4 immunostaining was focally increased in the podocytes in PAN nephropathy but not in ANA nephropathy. In proteinuric podocytes, the expression of JAM4 was distinct from that of MAGI-1 or other slit diaphragm molecules such as nephrin and ZO-1. Close colocalization of JAM4 and ezrin was maintained in PAN nephropathy. By immunoelectron microscopy, the signals for JAM4 were detected at the free apical membrane of the podocytes with effaced foot processes. Studies with selective detergent extract revealed that the subcellular localization of JAM4 was altered in PAN nephropathy. Thus the altered expression of JAM4 appears to be associated with morphological changes in podocytes and can be a useful marker of injured podocytes. JAM4 may have a different role at the apical membrane besides the role as a junctional molecule and is likely associated with the unique structure of this epithelium.

Amino Acid Sequence↗
PubMed2005

Nephrin and podocin dissociate at the onset of proteinuria in experimental membranous nephropathy.

BACKGROUND: The slit diaphragm plays a critical role in maintaining the barrier function of the glomerular capillary wall. The pathogenic mechanism of proteinuria in membranous nephropathy remains uncertain. This study was undertaken to analyze the pathogenic role of slit diaphragm in proteinuria in experimental membranous nephropathy. METHODS: The expression and the localization of slit diaphragm-associated molecules (nephrin, podocin, and CD2AP) and other podocyte-associated molecules (podocalyxin and alpha(3) integrin) in passive and active Heymann nephritis were analyzed by immunofluorescence and Western blot analysis. The interaction of slit diaphragm-associated molecules was investigated by the dual-labeling immunofluorescence method. The mRNA expression of these molecules was also analyzed. RESULTS: Shifts in nephrin and podocin staining patterns, from linear to granular, were detected in the early stages of passive Heymann nephritis. These shifts were not parallel, and the dissociation of these molecules was detected by the dual-labeling immunofluorescence method in passive and active Heymann nephritis. Western blot analyses with sequentially solubilized materials indicated that the nephrin-rich fraction changed from being partly detergent-resistant to being predominantly detergent-soluble. This change did not occur with podocin. Nephrin excreted into urine was already detected in the early stages of passive Heymann nephritis. Decreased mRNA expression of nephrin and podocin was observed before the onset of proteinuria. By contrast, no extensive change in the expression of alpha(3) integrin was observed in this study. CONCLUSION: Nephrin is dissociated from podocin and excreted into urine in the early stages of Heymann nephritis. The reduced expression of nephrin and podocin, along with their dissociation, may contribute to the development of proteinuria in Heymann nephritis.

Adaptor Proteins, Signal Transducing↗
PubMed2004

ANCA-related crescentic glomerulonephritis in a patient with scleroderma without marked dermatological change and malignant hypertension.

A 64-year-old woman with scleroderma without marked dermatological change developed anti-neutrophil cytoplasmic autoantibody (ANCA)-related renal failure. She had neither malignant hypertension nor elevation of plasma renin concentration. Renal biopsy showed crescentic glomerulonephritis (pauci-immune type) and the myeloperoxidase-specific anti-neutrophil cytoplasmic autoantibody (MPO-ANCA) titer was found to be elevated to 757 IU/ml. Methylprednisolone pulse therapy followed by oral prednisolone effectively suppressed renal failure and lowered the MPO-ANCA titer. We believe this is a rare case of ANCA-related renal failure in a patient with scleroderma without marked dermatological change.

Anti-Inflammatory Agents↗
PubMed2003

[A case of strongyloidiasis hyperinfection during oral corticosteroid therapy associated with a nephrotic patient infected with HTLV-1].

There have been some reports of disseminated Strongyloidiasis associated with immunosuppressive therapy around the endemic area. We encountered an elderly patient with Strongyloidiasis hyperinfection during corticosteroid therapy. The case was a 75-year-old man, living in Tokunoshima, Kagoshima Prefecture, who had no remarkable past history. He visited a clinic because of exertional dyspnea and edema of the lower limbs. Laboratory examination showed renal dysfunction, microscopic hematuria and proteinuria. On December 2000, he was admitted to our hospital on a suspected diagnosis of rapidly progressive glomerulonephritis. Further examinations showed normal serum creatinine, severe microscopic hematuria and proteinuria of more than 3 g per day. Although we wanted to determine a treatment based on a pathologic diagnosis, considered his age and severe kyphosis, he had 30 mg of prednisolone as an empiric treatment. Strongyloides stercoralis were identified from his sputa and stool by microscopic investigation 21 days after initiation of corticosteroid therapy. Subsequently, 6 mg of Ivermectin was given twice every two weeks. S. stercoralis were eradicated and his proteinuria improved. This case suggests that S. stercoralis could be the cause of urine abnormality.

Aged↗