Biology subjects

Yanagita, M.

Publications and source records attributed to Yanagita, M..

6 recordsLinked to original sources

bioRxiv2024

Renal Proximal Tubule Cell-specific Megalin Deletion Induces Tubulointerstitial Nephritis in Mice Fed Western Diet

BackgroundPharmacological inhibition of megalin (also known as low-density lipoprotein receptor-related protein 2: LRP2) attenuates atherosclerosis in hypercholesterolemic mice. Since megalin is abundant in renal proximal tubule cells (PTCs), the purpose of this study was to determine whether PTC-specific deletion of megalin reduces hypercholesterolemia-induced atherosclerosis in mice. MethodsFemale Lrp2 f/f mice were bred with male Ndrg1-Cre ERT2 +/0 mice to develop PTC-LRP2 +/+ and -/- littermates. To study atherosclerosis, all mice were bred to an LDL receptor -/- background and fed a Western diet to induce atherosclerosis. ResultsPTC-specific megalin deletion did not attenuate atherosclerosis in LDL receptor -/- mice in either sex. Serendipitously, we discovered that PTC-specific megalin deletion led to interstitial infiltration of CD68+ cells and tubular atrophy. The pathology was only evident in male PTC-LRP2 -/- mice fed the Western diet, but not in mice fed a normal laboratory diet. Renal pathologies were also observed in male PTC-LRP2 -/- mice in an LDL receptor +/+ background fed the same Western diet, demonstrating that the renal pathologies were dependent on diet and not hypercholesterolemia. In contrast, female PTC-LRP2 -/- mice had no apparent renal pathologies. In vivo multiphoton microscopy demonstrated that PTC-specific megalin deletion dramatically diminished albumin accumulation in PTCs within 10 days of Western diet feeding. RNA sequencing analyses demonstrated the upregulation of inflammation-related pathways in kidney. ConclusionsPTC-specific megalin deletion does not affect atherosclerosis, but leads to tubulointerstitial nephritis in mice fed Western diet, with severe pathologies in male mice.

pathology↗

bioRxiv2024

Visualization of intracellular ATP dynamics in the whole kidney under pathophysiological conditions using the kidney slice culture system

ATP depletion plays a central role in the pathogenesis of kidney diseases. Recently, we reported spatiotemporal intracellular ATP dynamics during ischemia reperfusion (IR) using GO-ATeam2 mice systemically expressing an ATP biosensor. However, observation from the kidney surface did not allow visualization of deeper nephrons or accurate evaluation of ATP synthesis pathways. Here we established a novel ATP imaging system using slice culture of GO-ATeam2 mouse kidneys, evaluated ATP synthesis pathway, and analyzed intracellular ATP dynamics using ex vivo IR and cisplatin nephropathy models. We demonstrated that proximal tubules (PTs) were strongly dependent on oxidative phosphorylation (OXPHOS), whereas podocytes relied on both OXPHOS and glycolysis using ATP synthesis inhibitors. We also confirmed that the ex vivo IR model could recapitulate ATP dynamics in vivo; ATP recovery in PTs after reperfusion varied depending on ischemia length, whereas ATP in distal tubules (DTs) recovered well even after long ischemia. After cisplatin administration, ATP levels in PTs decreased first, followed by a decrease in DTs. An organic cation transporter 2 inhibitor suppressed cisplatin uptake in kidney slices, leading to better ATP recovery in PTs, but not in DTs. Finally, we confirmed that a mitochondria protection reagent delayed cisplatin-induced ATP decrease in PTs. This novel system may provide new insights into the energy dynamics and pathogenesis of kidney disease.

molecular biology↗

bioRxiv2022

Robust capability of renal tubule fatty acid uptake from apical and basolateral membranes in physiology and disease

Excess lipid accumulation is associated with obesity-related chronic kidney disease, but the mechanisms of fatty acid (FA) uptake have been poorly understood. To this end, we investigated how FAs are taken up by tubular epithelial cells (TECs) in mice by using in vivo FA tracing and histological methods. Immunohistochemistry showed that CD36, which is a well-known FA transporter, was abundantly expressed on the basolateral side of proximal TECs (PTECs). The uptake of 125I-BMIPP (a radiolabeled FA tracer) was significantly reduced in CD36-knockout kidneys at 1 min after injection. In vivo imaging with multiphoton microscopy revealed that BODIPY-C12 (a fluorescence-labeled FA tracer) accumulated on both the basolateral and apical sides of PTECs. Numerous lipid droplets accumulated in PTECs after accelerated lipolysis. Furthermore, PTEC-specific injury via diphtheria toxin (DT) injection in transgenic mice expressing the DT receptor resulted in a compensatory increase in lipid accumulation in downstream TECs. Importantly, urinary FAs were undetectable, even in mice and humans with remarkable albuminuria. Our data demonstrate that renal TECs take up FAs from blood (CD36-dependent) and primary urine (CD36-independent) and can store excess FAs as neutral lipids. The results further show that renal tubules have hitherto largely unappreciated mechanisms by which the excretion of FAs into the urine is avoided.

biochemistry↗

bioRxiv2020

Reconstitution of Alveolar Regeneration via novel DATPs by Inflammatory Niches

Tissue regeneration involves a multi-step process composed of diverse cellular hierarchies and states that are also implicated in tissue dysfunction and pathogenesis. Here, we leveraged single-cell RNA sequencing analysis in combination with in vivo lineage tracing and organoid models to fine-map trajectories of alveolar lineage cells during injury repair and regeneration. We identified Damage-Associated Transient Progenitors (DATPs) as a distinct AT2-lineaged population arising during alveolar regeneration. Specifically, we found that IL-1{beta}, secreted by interstitial macrophages, primes a subset of Il1r1+AT2 cells for conversion into DATPs, via a Hif1a-mediated glycolysis pathway, that are functional mediators for mature AT1 cell differentiation. Importantly, we show that chronic inflammation mediated by IL-1{beta} prevents differentiation into AT1 cells, leading to aberrant accumulation of DATPs and impaired alveolar differentiation. Our step-wise fine-mapping of cell fate transitions demonstrates how the inflammatory niche impedes alveolar regeneration by directing stem cell fate behavior.

cell biology↗

bioRxiv2020

Visualizing ATP Dynamics in Live Mice

ABSTRACTAnalysis of the dynamics of adenosine triphosphate (ATP) is vital to quantitatively define the actual roles of ATP in biological activities. Here, we applied a genetically encoded Förster resonance energy transfer biosensor “GO-ATeam” and created a transgenic mouse model that allows systemic ATP levels to be quantitatively, sensitively, noninvasively, and spatiotemporally measured under physiological and pathological conditions. We used this model to readily conduct intravital imaging of ATP dynamics under three different conditions: during exercise, in all organs and cells; during myocardial infarction progression; and in response to the application of cardiotoxic drugs. These findings provide compelling evidence that the GO-ATeam mouse model is a powerful tool to investigate the multifarious functions of cellular ATP in vivo with unprecedented spatiotemporal resolution in real-time. This will inform predictions of molecular and morphological responses to perturbations of ATP levels, as well as the elucidation of physiological mechanisms that control ATP homeostasis.One Sentence Summary Intravital real-time imaging of ATP dynamics in multiple organs using GO-ATeam mice, can be used to quantitatively, sensitively, noninvasively, and spatiotemporally measure systemic ATP levels and provide a platform for preclinical pharmacological studies.Competing Interest StatementM.Yamamoto is involved in a pending patent related to GO-ATeam mice. H.I. holds a patent for ATeam probe. All other authors declare no competing interests.View Full Text

physiology↗

bioRxiv2019

Proteolytic Cleavage by Matriptase Exacerbating Kidney Injury: a Novel Therapeutic Target

Chronic kidney disease (CKD) is a progressive disease, and podocyte injury is a potential mechanism. We found that Matriptase was activated at podocytes in CKD patients and mice while a Matriptase inhibitor slowed the progression of mouse kidney disease. The mechanism could be accounted for by an imbalance favoring Matriptase over its cognate inhibitor, hepatocyte growth factor activator inhibitor type 1 (HAI-1), as conditional depletion of HAI-1 in podocytes accelerates podocyte injury. Intriguingly, the N-terminal of Podocin (Podocin-N), as a consequence of Matriptase cleavage of Podocin, translocates to nucleoli. These results suggest that aberrant activation of Matriptase would cause podocyte injury, and a targeting Matriptase could be a novel therapeutic strategy for CKD patients. Significant statementChronic kidney disease (CKD) is a progressive disease. If podocytes, which are specialized cells of the kidney glomerulus that wrap around capillaries, are injured, kidney injury is exacerbated. Thus, a therapeutic strategy to addressing CKD would be to block podocyte injury. The present study provides evidence that Matriptase cleaves Podocin, a component of podocyte slit membrane, and the N-terminal of podocin translocates to nucleoli, causing kidney injury. Our findings show that the N-terminal of Podocin plays an efficient role for cell fate in podocytes. In addition, the inhibition of Matriptase would be a potential therapeutic target for CKD.

biochemistry↗