Publications by authors named "Toshiaki Usui"

Monocytes and macrophages express the transcription factor MAFB (V-maf musculoaponeurotic fibrosarcoma oncogene homolog B) and protect against ischemic acute kidney injury (AKI). However, the mechanism through which MAFB alleviates AKI in macrophages remains unclear. In this study, we induced AKI in macrophage lineage-specific Mafb-deficient mice (C57BL/6J) using the ischemia-reperfusion injury model to analyze these mechanisms.

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Article Synopsis
  • The study investigates the mechanisms behind decreased kidney function in autosomal dominant polycystic kidney disease (ADPKD), finding that specific hemodynamic changes occur in patients over time.
  • Although kidney cyst enlargement is understood, the link between total kidney volume and renal dysfunction remains unclear, prompting detailed examination of glomerular hemodynamics in ADPKD progression.
  • Results show that over two years, total kidney volume increased, while glomerular filtration rate and renal plasma flow decreased, revealing an inverse correlation between baseline kidney volume and filtration rate, but not with other hemodynamic parameters.
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The increasing number of patients with chronic kidney disease (CKD) is being recognized as an emerging global health problem. Recently, it has become clear that injury and loss of glomerular visceral epithelial cells, known as podocytes, is a common early event in many forms of CKD. Podocytes are highly specialized epithelial cells that cover the outer layer of the glomerular basement membrane.

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Article Synopsis
  • Focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome that resists steroid treatment, often leading to kidney failure, with spontaneous recovery being uncommon.
  • The study reveals that the basic leucine zipper transcription factor, MafB, is crucial for podocyte function and is decreased in patients with FSGS; mice lacking MafB specifically in podocytes developed FSGS and severe proteinuria.
  • Overexpressing MafB in podocytes of transgenic mice was found to reduce adriamycin-induced FSGS symptoms, suggesting MafB as a potential new target for FSGS therapies.
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The glomerular filtration barrier is composed of podocytes, glomerular basement membrane, and endothelial cells. Disruption of these structures causes several glomerular injuries, such as focal segmental glomerulosclerosis (FSGS). The surface of podocyte apical membranes is coated by negatively charged sialic acids on core 1-derived mucin-type O-glycans.

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The transcription factor, MafB, plays important role in the differentiation and functional maintenance of various cells and tissues, such as the inner ear, kidney podocyte, parathyroid gland, pancreatic islet, and macrophages. The rare heterozygous substitution (p.Leu239Pro) of the DNA binding domain in MAFB is the cause of Focal Segmental Glomerulosclerosis associated with Duane Retraction Syndrome, which is characterized by impaired horizontal eye movement due to cranial nerve maldevelopment in humans.

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Multicentric carpotarsal osteolysis (MCTO) is a condition involving progressive osteolysis of the carpal and tarsal bones that is associated with glomerular sclerosis and renal failure (MCTO nephropathy). Previous work identified an autosomal dominant missense mutation in the transactivation domain of the transcription factor MAFB as the cause of MCTO. Several methods are currently used for MCTO nephropathy treatment, but these methods are invasive and lead to severe side effects, limiting their use.

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Article Synopsis
  • - Focal segmental glomerulosclerosis (FSGS) is a major cause of kidney failure in both children and adults, with genetic factors playing a crucial role, especially in early-onset cases, while many adult cases remain unexplained.
  • - A study on two families with FSGS linked to Duane Retraction Syndrome found a rare genetic mutation (p.Leu239Pro) in the MAFB gene, which is involved in the development of kidney cells (podocytes) and other structures affected by the syndrome.
  • - The mutation in MAFB was shown to disrupt its function, leading to impaired podocyte differentiation and affecting the development of certain nerves and hearing ability, highlighting the specific role of MAFB
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The transcription factor MAFB is an important regulator of the development and differentiation of various organs and tissues. Previous studies have shown that MAFB is expressed in embryonic and adult mouse testes and is expected to act as the downstream target of retinoic acid (RA) to initiate spermatogenesis. However, its exact localization and function remain unclear.

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The transcription factor MafB is expressed by monocytes and macrophages. Efferocytosis (apoptotic cell uptake) by macrophages is important for inhibiting the development of autoimmune diseases, and is greatly reduced in Mafb-deficient macrophages. Here, we show the expression of the first protein in the classical complement pathway C1q is important for mediating efferocytosis and is reduced in Mafb-deficient macrophages.

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The transcription factor MafB is essential for development of the parathyroid glands, the expression of which persists after morphogenesis and in adult parathyroid glands. However, the function of MafB in adult parathyroid tissue is unclear. To investigate this, we induced chronic kidney disease (CKD) in wild-type and MafB heterozygote (MafB+/-) mice by feeding them an adenine-supplemented diet, leading to secondary hyperparathyroidism.

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Patients with anti-glomerular basement membrane antibody glomerulonephritis (anti-GBM GN) have severe kidney dysfunction, leading to end-stage renal disease. The effect of plasmapheresis and immunosuppressive treatment in patients with severe glomerular changes is controversial. A 62-year-old man was admitted with rapidly progressive glomerulonephritis and diagnosed with anti-GBM GN.

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We report here two cases of autosomal dominant polycystic kidney disease (ADPKD) with renal dysfunction that were treated with tolvaptan. Case 1 was a 47-year-old man with a glomerular filtration rate (GFR) of 17.0 ml/min/1.

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