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1.
J Clin Med ; 12(16)2023 Aug 19.
Article in English | MEDLINE | ID: mdl-37629437

ABSTRACT

Full endoscopic techniques are becoming more popular for degenerative lumbar pathologies. Percutaneous endoscopic lumbar interbody fusion (PETLIF) is a minimally invasive surgical technique for spondylolisthesis and lumbar spinal canal stenosis with instability. Nagahama first introduced PETLIF in 2019. This study investigated the clinical outcomes and complications of 24 patients who underwent PETLIF in our facility and compared them with previous studies. Literature searches were conducted on PubMed and Web of Science. The PETLIF surgical technique involves three steps to acquire disc height under general anesthesia. The procedure includes bone harvesting, spondylolisthesis reduction, endoscopic foraminoplasty, disc height expansion using an oval dilator, and intervertebral disc curettage. A cage filled with autologous bone is inserted into the disc space and secured with posterior fixation. Patients underwent PETLIF with an average operation time of 130.8 min and a blood loss of 24.0 mL. Postoperative hospital stays were 9.5 days. Improvement in VAS, disc height, spinal canal area, and % slip was observed, while lumbar lordosis remained unchanged. Complications included end plate injury, subsidence, and exiting nerve root injury. The differences between PETLIF and the extracted literature were found in patients' age, direct decompression, epidural or local anesthesia, approach, order of PPS, and cage insertion. In conclusion, PETLIF surgery is a practical, minimally invasive surgical technique for patients with lumbar degenerative diseases suffering from back and leg pain, demonstrating significant improvements in pain scores. However, it is essential to carefully consider the potential complications and continue to refine the surgical technique further to enhance the safety and efficacy of this procedure.

2.
FASEB J ; 37(1): e22680, 2023 01.
Article in English | MEDLINE | ID: mdl-36468710

ABSTRACT

Spermatid production is a complex regulatory process in which coordination between hormonal control and apoptosis plays a pivotal role in maintaining a balanced number of sperm cells. Apoptosis in spermatogenesis is controlled by pro-apoptotic and anti-apoptotic molecules. Hormones involved in the apoptotic process during spermatogenesis include gonadotrophins, sex hormones, and glucocorticoid (GC). GC acts broadly as an apoptosis inducer by binding to its receptor (glucocorticoid receptor: GR) during organ development processes, such as spermatogenesis. However, the downstream pathway induced in GC-GR signaling and the apoptotic process during spermatogenesis remains poorly understood. We reported previously that GC induces full-length glucocorticoid-induced transcript 1 (GLCCI1-long), which functions as an anti-apoptotic mediator in thymic T cell development. Here, we demonstrate that mature murine testis expresses a novel isoform of GLCCI1 protein (GLCCI1-short) in addition to GLCCI1-long. We demonstrate that GLCCI1-long is expressed in spermatocytes along with GR. In contrast, GLCCI1-short is primarily expressed in spermatids where GR is absent; instead, the estrogen receptor is expressed. GLCCI1-short also binds to LC8, which is a known mediator of the anti-apoptotic effect of GLCCI1-long. A luciferase reporter assay revealed that ß-estradiol treatment synergistically increased Glcci1-short promotor-driven luciferase activity in Erα-overexpressing cells. Together with the evidence that the conversion of testosterone to estrogen is preceded by aromatase expression in spermatids, we hypothesize that estrogen induces GLCCI1-short, which, in turn, may function as a novel anti-apoptotic mediator in mature murine testis.


Subject(s)
Glucocorticoids , Semen , Male , Mice , Animals , Spermatogenesis , Spermatids , Estrogens
3.
Mod Rheumatol ; 33(5): 1021-1029, 2023 Aug 25.
Article in English | MEDLINE | ID: mdl-36112493

ABSTRACT

OBJECTIVES: Although epidemiological surveys of paediatric rheumatic diseases in Japan have been conducted, they were single surveys with no continuity. This is the first report of the Pediatric Rheumatology Association of Japan registry database, which was established to continuously collect data for paediatric rheumatic diseases. METHODS: Pediatric Rheumatology International Collaborate Unit Registry version 2 (PRICUREv2) is a registry database established by the Pediatric Rheumatology Association of Japan. The registry data were analysed for the age of onset, time to diagnosis, sex differences, seasonality, and other factors. RESULTS: Our data showed the same trend regarding rates of paediatric rheumatic diseases reported in Japan and other countries. The age of onset was lower in juvenile idiopathic arthritis (JIA) and juvenile dermatomyositis and higher in systemic lupus erythematosus and Sjögren's syndrome. The time to diagnosis was relatively short in JIA and systemic lupus erythematosus but longer in juvenile dermatomyositis and Sjögren's syndrome. Rheumatoid factor-positive polyarticular JIA showed a seasonality cluster with regard to onset. CONCLUSION: PRICUREv2 aided the retrieval and evaluation of current epidemiological information on patients with paediatric rheumatic diseases. It is expected that the data collection will be continued and will be useful for expanding research in Japan.


Subject(s)
Arthritis, Juvenile , Dermatomyositis , Lupus Erythematosus, Systemic , Rheumatic Diseases , Rheumatology , Sjogren's Syndrome , Child , Humans , Male , Female , Rheumatic Diseases/epidemiology , Dermatomyositis/diagnosis , Dermatomyositis/epidemiology , Sjogren's Syndrome/diagnosis , Sjogren's Syndrome/epidemiology , Japan/epidemiology , Arthritis, Juvenile/epidemiology , Registries , Lupus Erythematosus, Systemic/diagnosis , Lupus Erythematosus, Systemic/epidemiology
4.
World Neurosurg ; 168: 324-332, 2022 12.
Article in English | MEDLINE | ID: mdl-36527212

ABSTRACT

Lumbar disc herniation (LDH) is a frequently encountered pathologic condition in orthopedic daily practice. Discectomy is considered when patients with LDH experience persistent limb or lumbar pain or neurologic deficits. Various minimally invasive techniques are available for discectomy. Among these techniques, full-endoscopic lumbar discectomy (FED) is one of the least invasive options. During FED, removal of LDH is accomplished using 2 major approaches: transforaminal (TF) or interlaminar (IL). The prototype FED was percutaneous nucelotomy. An endoscope was integrated to percutaneous nucelotomy and TF endoscopic lumbar discectomy (TELD) was first derived. IL endoscopic lumbar discectomy (IELD) was introduced years after TELD. TELD and IELD can compensate for the shortcomings of each other and endoscopic spine surgeons need to acquire both techniques to deal with all type of LDHs. Because of its long history, the TF approach seems to represent the major approach for FED, but the IL approach has numerous benefits in particular types of LDH. The present article focuses on IELD and reviews the history, surgical techniques, indications and contraindications, clinical outcomes, and complications. This review will contribute to improved understanding of IELD as an important technique in full-endoscopic spine surgery.


Subject(s)
Diskectomy, Percutaneous , Intervertebral Disc Displacement , Humans , Diskectomy, Percutaneous/methods , Lumbar Vertebrae/surgery , Intervertebral Disc Displacement/surgery , Diskectomy/methods , Endoscopy/methods , Treatment Outcome , Retrospective Studies
6.
Biochem Biophys Res Commun ; 614: 198-206, 2022 07 23.
Article in English | MEDLINE | ID: mdl-35605301

ABSTRACT

Podocyte damage is a major pathological lesion leading to focal segmental glomerulosclerosis (FSGS). Podocytes damaged by cellular stress undergo hypertrophy to compensate for podocytopenia. It is known that cyclin-dependent kinase inhibitors induced by p53 ensure podocytes hypertrophy; however, its precise mechanism remains to be further investigated. In this study, we found that ubiquitin specific protease 40 (USP40) is a novel regulator of p53. Although USP40 knockout mice established in the present study revealed no abnormal kidney phenotype, intermediate filament Nestin was upregulated in the glomeruli, and was bound to and colocalized with USP40. We also found that USP40 deubiquitinated histidine triad nucleotide-binding protein 1 (HINT1), an inducer of p53. Gene knockdown experiments of USP40 in cultured podocytes revealed the reduction of HINT1 and p53 protein expression. Finally, in glomerular podocytes of mouse FSGS, upregulation of HINT1 occurred in advance of the proteinuria, which was followed by upregulation of USP40, p53 and Nestin. In conclusion, USP40 bound to Nestin deubiquitinates HINT1, and in consequence upregulates p53. These results provide additional insight into the pathological mechanism of podocyte hypertrophy in FSGS.


Subject(s)
Glomerulosclerosis, Focal Segmental , Nerve Tissue Proteins , Nestin , Podocytes , Tumor Suppressor Protein p53 , Ubiquitin-Specific Proteases , Animals , Deubiquitinating Enzymes/genetics , Deubiquitinating Enzymes/metabolism , Glomerulosclerosis, Focal Segmental/genetics , Glomerulosclerosis, Focal Segmental/metabolism , Glomerulosclerosis, Focal Segmental/pathology , Hypertrophy , Mice , Mice, Knockout , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Nestin/genetics , Nestin/metabolism , Podocytes/metabolism , Podocytes/pathology , Podocytes/physiology , Protein Kinase C/antagonists & inhibitors , Stress, Physiological/genetics , Stress, Physiological/physiology , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism , Ubiquitin-Specific Proteases/genetics , Ubiquitin-Specific Proteases/metabolism , Ubiquitination , Up-Regulation
7.
Case Rep Orthop ; 2021: 6443618, 2021.
Article in English | MEDLINE | ID: mdl-34745676

ABSTRACT

We report a case of tibial condylar valgus osteotomy (TCVO) for ipsilateral knee osteoarthritis (OA) after hip arthrodesis. A 58-year-old woman developed right purulent hip arthritis at one month of age and underwent right hip fusion at 16 years old. She visited our department at the age of 57 because her right knee joint pain worsened. The range of motion for her right knee was 80° and -5° of flexion and extension, respectively, and she experienced medial weight-bearing pain. A plain X-ray image showed that the right knee joint had end-stage knee OA with a bone defect inside the tibia, and the tibial plateau shape was the pagoda type. There was a marked instability in her right knee with a valgus of 9° and varus of 7° on stress photography. She underwent TCVO on her right knee and was allowed full load four weeks after surgery. Computed tomography imaging showed bone union nine months after surgery. Two years after the operation, there was no correction loss, and she could walk independently without pain. In general, total knee arthroplasty (TKA) is indicated for end-stage knee OA; however, there are problems, such as early loosening due to the increased mechanical load on the knee after hip OA. In this case, since a good course was obtained, TCVO is considered a treatment option for terminal knee OA after hip arthrodesis.

8.
Development ; 147(7)2020 04 06.
Article in English | MEDLINE | ID: mdl-32108024

ABSTRACT

Endothelial cell adhesion is implicated in blood vessel sprout formation, yet how adhesion controls angiogenesis, and whether it occurs via rapid remodeling of adherens junctions or focal adhesion assembly, or both, remains poorly understood. Furthermore, how endothelial cell adhesion is controlled in particular tissues and under different conditions remains unexplored. Here, we have identified an unexpected role for spatiotemporal c-Src activity in sprouting angiogenesis in the retina, which is in contrast to the dominant focus on the role of c-Src in the maintenance of vascular integrity. Thus, mice specifically deficient in endothelial c-Src displayed significantly reduced blood vessel sprouting and loss in actin-rich filopodial protrusions at the vascular front of the developing retina. In contrast to what has been observed during vascular leakage, endothelial cell-cell adhesion was unaffected by loss of c-Src. Instead, decreased angiogenic sprouting was due to loss of focal adhesion assembly and cell-matrix adhesion, resulting in loss of sprout stability. These results demonstrate that c-Src signaling at specified endothelial cell membrane compartments (adherens junctions or focal adhesions) control vascular processes in a tissue- and context-dependent manner.


Subject(s)
Cell Adhesion/genetics , Endothelial Cells/physiology , Focal Adhesions/genetics , Genes, src/physiology , Neovascularization, Physiologic/genetics , Retina/embryology , Animals , Cells, Cultured , Embryo, Mammalian , Endothelium, Vascular/embryology , Endothelium, Vascular/metabolism , Female , Focal Adhesions/metabolism , Focal Adhesions/physiology , HEK293 Cells , Human Umbilical Vein Endothelial Cells , Humans , Male , Mice , Mice, Knockout , Retina/metabolism
9.
FASEB J ; 33(6): 7387-7402, 2019 06.
Article in English | MEDLINE | ID: mdl-30860871

ABSTRACT

Glucocorticoids (GCs) potently induce T-cell apoptosis in a GC receptor (GR)-dependent manner and are used to control lymphocyte function in clinical practice. However, its downstream pathways remain controversial. Here, we showed that GC-induced transcript 1 (GLCCI1) is a novel downstream molecule of the GC-GR cascade that acts as an antiapoptotic mediator in thymic T cells. GLCCI1 was highly phosphorylated and colocalized with microtubules in GLCCI1-transfected human embryonic kidney QBI293A cells. GR-dependent up-regulation of GLCCI1 was associated with GC-induced proapoptotic events in a cultured thymocyte cell line. However, GLCCI1 knockdown in a thymocyte cell line led to apoptosis. Consistently, transgenic mice overexpressing human GLCCI1 displayed enlarged thymi that consisted of larger numbers of thymocytes. Further molecular characterization showed that GLCCI1 bound to both dynein light chain LC8-type 1 (LC8) and its functional kinase, p21-protein activated kinase 1 (PAK1), thereby inhibiting the kinase activity of PAK1 toward LC8 phosphorylation, a crucial event in apoptotic signaling. GLCCI1 induction facilitated LC8 dimer formation and reduced Bim expression. Thus, GLCCI1 is a candidate factor involved in apoptosis regulation of thymic T cells.-Kiuchi, Z., Nishibori, Y., Kutsuna, S., Kotani, M., Hada, I., Kimura, T., Fukutomi, T., Fukuhara, D., Ito-Nitta, N., Kudo, A., Takata, T., Ishigaki, Y., Tomosugi, N., Tanaka, H., Matsushima, S., Ogasawara, S., Hirayama, Y., Takematsu, H., Yan, K. GLCCI1 is a novel protector against glucocorticoid-induced apoptosis in T cells.


Subject(s)
Apoptosis/physiology , Glucocorticoids/physiology , Receptors, Glucocorticoid/physiology , T-Lymphocytes/cytology , Amino Acid Sequence , Animals , Apoptosis/drug effects , Bcl-2-Like Protein 11/biosynthesis , Bcl-2-Like Protein 11/genetics , Cell Line , Cytoplasmic Dyneins/metabolism , Dimerization , Down-Regulation , Gene Knockdown Techniques , Glucocorticoids/pharmacology , Humans , Hypertrophy , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Microtubules/metabolism , Phosphorylation , Protein Interaction Mapping , Protein Processing, Post-Translational , RNA Interference , RNA, Small Interfering/genetics , RNA, Small Interfering/pharmacology , Receptors, Glucocorticoid/genetics , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Signal Transduction/physiology , Thymus Gland/pathology , p21-Activated Kinases/metabolism
11.
PLoS One ; 13(8): e0202400, 2018.
Article in English | MEDLINE | ID: mdl-30125302

ABSTRACT

The evidence that gene mutations in the polarity determinant Crumbs homologs-2 (CRB2) cause congenital nephrotic syndrome suggests the functional importance of this gene product in podocyte development. Because another isoform, CRB3, was reported to repress the mechanistic/mammalian target of the rapamycin complex 1 (mTORC1) pathway, we examined the role of CRB2 function in developing podocytes in relation to mTORC1. In HEK-293 and MDCK cells constitutively expressing CRB2, we found that the protein localized to the apicolateral side of the cell plasma membrane and that this plasma membrane assembly required N-glycosylation. Confocal microscopy of the neonate mouse kidney revealed that both the tyrosine-phosphorylated form and non-phosphorylated form of CRB2 commence at the S-shaped body stage at the apicolateral side of podocyte precursor cells and move to foot processes in a capillary tuft pattern. The pattern of phosphorylated mTOR in developing podocytes was similar to that of CRB2 tyrosine phosphorylation. Additionally, the lack of a tyrosine phosphorylation site on CRB2 led to the reduced sensitivity of mTORC1 activation in response to energy starvation. CRB2 may play an important role in the mechanistic pathway of developing podocytes through tyrosine phosphorylation by associating with mTORC1 activation.


Subject(s)
Carrier Proteins/metabolism , Cell Membrane/metabolism , Mechanistic Target of Rapamycin Complex 1/metabolism , Membrane Proteins/metabolism , Podocytes/metabolism , Stem Cells/metabolism , Animals , Carrier Proteins/genetics , Cell Membrane/genetics , Dogs , Glycosylation , HEK293 Cells , Humans , Madin Darby Canine Kidney Cells , Male , Mechanistic Target of Rapamycin Complex 1/genetics , Membrane Proteins/genetics , Mice , Phosphorylation/genetics , Podocytes/cytology , Stem Cells/cytology
12.
Pediatrics ; 139(2)2017 Feb.
Article in English | MEDLINE | ID: mdl-28104732

ABSTRACT

Iatrogenic Cushing's syndrome (CS) is a severe adverse effect of systemic glucocorticoid (GC) therapy in children, but is extremely rare in the setting of topical ocular GC therapy. In this article, we report the case of a 9-year-old girl suffering from idiopathic uveitis who developed CS due to topical ocular GC treatment. She was referred to the ophthalmology department with a complaint of painful eyes, at which time she was diagnosed with bilateral iridocyclitis and started on a treatment of betamethasone sodium phosphate eye drops. Six months after the initiation of topical ocular GC treatment, she was referred to our pediatric department with stunted growth, truncal obesity, purple skin striate, buffalo hump, and moon face. Because her serum cortisol and plasma adrenocorticotropic hormone levels were undetectable, she was diagnosed with iatrogenic CS. After the doses of topical ocular GC were reduced, the clinical symptoms of CS were improved. The fact that the amount of topical ocular GC with our patient was apparently less than that of similar previous cases tempted us to perform genetic analysis of her NR3C1 gene. We found that our patient had a single heterozygous nucleotide substitution in the 3' untranslated region of the NR3C1 gene, which may explain why she developed CS. However, additional investigations are required to determine if our findings can be extrapolated to other patients. In conclusion, clinicians should be aware that even extremely low doses of topical ocular steroid therapy can cause iatrogenic CS.


Subject(s)
Betamethasone/analogs & derivatives , Cushing Syndrome/chemically induced , Glucocorticoids/adverse effects , Ophthalmic Solutions , Betamethasone/adverse effects , Child , Female , Humans , Iatrogenic Disease , Mutation , Receptors, Glucocorticoid/genetics , Uveitis/drug therapy
13.
Sci Signal ; 9(437): ra72, 2016 07 19.
Article in English | MEDLINE | ID: mdl-27436360

ABSTRACT

Activation of vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) by VEGF binding is critical for vascular morphogenesis. In addition, VEGF disrupts the endothelial barrier by triggering the phosphorylation and turnover of the junctional molecule VE-cadherin, a process mediated by the VEGFR2 downstream effectors T cell-specific adaptor (TSAd) and the tyrosine kinase c-Src. We investigated whether the VEGFR2-TSAd-c-Src pathway was required for angiogenic sprouting. Indeed, Tsad-deficient embryoid bodies failed to sprout in response to VEGF. Tsad-deficient mice displayed impaired angiogenesis specifically during tracheal vessel development, but not during retinal vasculogenesis, and in VEGF-loaded Matrigel plugs, but not in those loaded with FGF. The SH2 and proline-rich domains of TSAd bridged VEGFR2 and c-Src, and this bridging was critical for the localization of activated c-Src to endothelial junctions and elongation of the growing sprout, but not for selection of the tip cell. These results revealed that vascular sprouting and permeability are both controlled through the VEGFR2-TSAd-c-Src signaling pathway in a subset of tissues, which may be useful in developing strategies to control tissue-specific pathological angiogenesis.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Endothelial Cells/metabolism , Neovascularization, Pathologic/metabolism , Signal Transduction , Vascular Endothelial Growth Factor Receptor-2/metabolism , src-Family Kinases/metabolism , Adaptor Proteins, Signal Transducing/genetics , Animals , CSK Tyrosine-Protein Kinase , Cell Line , Endothelial Cells/pathology , Mice , Mice, Knockout , Neovascularization, Pathologic/genetics , Neovascularization, Pathologic/pathology , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolism , Vascular Endothelial Growth Factor Receptor-2/genetics , src-Family Kinases/genetics
14.
CEN Case Rep ; 2(2): 204-208, 2013 Nov.
Article in English | MEDLINE | ID: mdl-28509292

ABSTRACT

Granulomatosis with polyangiitis (GPA), previously referred to as Wegener's granulomatosis, is a rare necrotizing granulomatous vasculitis, especially in children. GPA affects small- to medium-sized vessels, leading to involvement of multiple organs, including the upper and lower respiratory tracts and kidneys. Glomerular lesions associated with GPA typically present as crescentic glomerulonephritis with necrotizing lesions, with little or no staining for immunoglobulins and complement proteins. We report a unique pediatric case of GPA associated with IgA nephropathy, a representative immune-mediated glomerular disease. The initial renal biopsy specimen revealed fibrous sclerosis and mild mesangial proliferation without deposition of IgA. However, after clinical remission of GPA by treatment, the serum IgA level continued to be significantly higher than normal, and her paranasal sinusitis was poorly controlled. An acute upper respiratory infection resulted in worsened urinary findings without any systemic signs of GPA. The second renal biopsy specimen revealed deposition of IgA and C3 in the mesangium. The patient was treated with oral prednisolone alone, which led to complete remission of proteinuria within 1 month. IgA nephropathy is possibly associated with GPA during remission stage, and serum IgA level may be a valuable indicator to predict its association.

15.
Cell Cycle ; 11(8): 1504-11, 2012 Apr 15.
Article in English | MEDLINE | ID: mdl-22433955

ABSTRACT

Podocytes are terminally differentiated post-mitotic cells similar to neurons, and their damage leads to nephrotic syndrome, which is characterized by massive proteinuria associated with generalized edema. A recent functional genetic approach has identified the pathological relevance of several mutated proteins in glomerular podocytes to the mechanism of proteinuria in hereditary nephrotic syndrome. In contrast, the pathophysiology of acquired primary nephrotic syndrome, including minimal change disease, is still largely unknown. We recently demonstrated the possible linkage of an energy-consuming process in glomerular podocytes to the mechanism of proteinuria. Puromycin aminonucleoside nephrosis, a rat model of minimal change disease, revealed the activation of the unfolded protein response (UPR) in glomerular podocytes to be a cause of proteinuria. The pretreatment of puromycin aminonucleoside rat podocytes and cultured podocytes with the mammalian target of rapamycin (mTOR) inhibitor everolimus further revealed that mTOR complex 1 consumed energy, which was followed by UPR activation. In this paper, we will review nutritional transporters to summarize the energy uptake process in podocytes and review the involvement of the UPR in the pathogenesis of glomerular diseases. We will also present additional data that reveal how mTOR complex 1 acts upstream of the UPR. Finally, we will discuss the potential significance of targeting the energy metabolism of podocytes to develop new therapeutic interventions for acquired nephrotic syndrome.


Subject(s)
Nephrotic Syndrome/metabolism , Podocytes/metabolism , AMP-Activated Protein Kinases/metabolism , Animals , Energy Metabolism , Everolimus , Glucose Transport Proteins, Facilitative/metabolism , Immunosuppressive Agents/pharmacology , Membrane Transport Proteins/metabolism , Nephrotic Syndrome/pathology , Podocytes/drug effects , Proteinuria/pathology , Rats , Sirolimus/analogs & derivatives , Sirolimus/pharmacology , TOR Serine-Threonine Kinases/antagonists & inhibitors , TOR Serine-Threonine Kinases/metabolism , Unfolded Protein Response
16.
Lab Invest ; 91(7): 992-1006, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21403644

ABSTRACT

Molecular mechanisms and signaling pathways leading to cellular proliferation and lesion formation in the crescentic glomerulonephritis (CGN) remain elusive. In the present study we have explored a potential role of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway and amino acid transporter (LAT) in the pathogenesis of CGN. Immunohistochemistry and western blot analysis of glomeruli isolated from a rat model of CGN revealed that activation of mTORC1 preceded crescent formation in glomerular parietal epithelial cells (PECs) and podocytes. Daily treatment of rats with the mTOR inhibitor everolimus just after induction of CGN was not beneficial and instead led to increased cellular necrosis of PECs. However, daily treatment starting 7 days after the onset of CGN was beneficial and maintained intact glomeruli. Out of three forms of L-type neutral amino acid transporters (LAT1-LAT3) studied here, only LAT2 was found to be upregulated in the PECs and podocytes in advance of the crescent formation as well as in the crescent lesion itself. Cell culture study revealed that plasma membrane expression of LAT2 markedly stimulated mTORC1 signaling pathway, which was significantly abrogated by coexistence of LAT inhibitor. Finally, LAT inhibitor significantly abrogated development of crescent formation of CGN on day 7. Our data suggest that LAT2 may have a pivotal role in the pathogenesis of CGN by activating the mTORC1 pathway in the glomerular epithelial cells.


Subject(s)
Amino Acid Transport System y+/physiology , Fusion Regulatory Protein 1, Light Chains/physiology , Glomerulonephritis/physiopathology , TOR Serine-Threonine Kinases/metabolism , Animals , Base Sequence , Blotting, Western , DNA Primers , Female , Glomerulonephritis/etiology , Immunohistochemistry , Rats , Rats, Inbred WKY , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction
17.
J Am Soc Nephrol ; 20(7): 1586-96, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19443642

ABSTRACT

LAT3 is a Na+-independent neutral l-amino acid transporter recently isolated from a human hepatocellular carcinoma cell line. Although liver, skeletal muscle, and pancreas are known to express LAT3, the tissue distribution and physiologic function of this transporter are not completely understood. Here, we observed that glomeruli express LAT3. Immunofluorescence, confocal microscopy, and immunoelectron microscopy revealed that LAT3 localizes to the apical plasma membrane of podocyte foot processes. In mice, starvation upregulated glomerular LAT3, phosphorylated AKT1, reconstituted the actin network, and elongated foot processes. In the fetal kidney, we observed intense LAT3 expression at the capillary loops stage of renal development. Finally, zebrafish morphants lacking lat3 function showed collapsed glomeruli with thickened glomerular basement membranes. Permeability studies of the glomerular filtration barrier in these zebrafish morphants demonstrated a disruption of selective glomerular permeability. Our data suggest that LAT3 may play a crucial role in the development and maintenance of podocyte structure and function by regulating protein synthesis and the actin cytoskeleton.


Subject(s)
Amino Acid Transport Systems, Basic/metabolism , Cell Differentiation/physiology , Kidney Glomerulus/metabolism , Podocytes/metabolism , Actins/metabolism , Amino Acid Transport Systems, Basic/genetics , Animals , Cell Membrane/metabolism , Cytoskeleton/metabolism , Female , Glomerular Basement Membrane/metabolism , Glomerular Filtration Rate/physiology , Humans , Kidney Glomerulus/cytology , Kidney Glomerulus/embryology , Male , Mice , Mice, Inbred ICR , Phosphorylation , Podocytes/cytology , Proto-Oncogene Proteins c-akt/metabolism , Zebrafish , Zebrafish Proteins/metabolism
18.
Am J Pathol ; 170(3): 888-98, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17322374

ABSTRACT

We recently cloned the human Na(+)-independent system L neutral amino acid transporter LAT3. The aim of the present study was to characterize the molecular nature of mouse LAT3 at the protein level. Isolated mouse LAT3 showed 83% identity to human LAT3. Xenopus oocytes injected with mouse LAT3 cRNA showed the same functional property as human LAT3. Reverse transcriptase-polymerase chain reaction revealed apparent transcripts of mouse LAT3 in the liver, skeletal muscle, and pancreas, an expression pattern identical to that found in humans. Antibody generated against mouse LAT3 detected both approximately 58-kd and 48-kd bands in the sample from liver and only a 48-kd band in skeletal muscle and pancreas. Immunohistochemical study showed its clear localization in the plasma membrane of liver and skeletal muscle, whereas it was only detectable in the endoplasmic reticulum and in crystalline inclusions in pancreatic acinar cells. Starvation induced up-regulation of mouse LAT3 protein and mRNA in both liver and skeletal muscle but not in pancreas. These results suggest that LAT3 may indeed function as an amino acid transporter, transporting branched-chain amino acids from liver and skeletal muscle to the bloodstream and thereby participating in the regulatory system of interorgan amino acid nutrition.


Subject(s)
Amino Acid Transport Systems, Basic/genetics , Amino Acid Transport Systems, Basic/metabolism , Amino Acids, Branched-Chain/metabolism , Starvation/metabolism , Animals , Base Sequence , Blotting, Western , Cells, Cultured , Cloning, Molecular , Fluorescent Antibody Technique , Humans , Immunohistochemistry , Male , Mice , Mice, Inbred ICR , Microscopy, Confocal , Microscopy, Electron, Transmission , Microscopy, Immunoelectron , Molecular Sequence Data , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Nucleic Acid
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