1
|
Kryvenko V, Vadász I. Alveolar-capillary endocytosis and trafficking in acute lung injury and acute respiratory distress syndrome. Front Immunol 2024; 15:1360370. [PMID: 38533500 PMCID: PMC10963603 DOI: 10.3389/fimmu.2024.1360370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/29/2024] [Indexed: 03/28/2024] Open
Abstract
Acute respiratory distress syndrome (ARDS) is associated with high morbidity and mortality but lacks specific therapeutic options. Diverse endocytic processes play a key role in all phases of acute lung injury (ALI), including the initial insult, development of respiratory failure due to alveolar flooding, as a consequence of altered alveolar-capillary barrier function, as well as in the resolution or deleterious remodeling after injury. In particular, clathrin-, caveolae-, endophilin- and glycosylphosphatidyl inositol-anchored protein-mediated endocytosis, as well as, macropinocytosis and phagocytosis have been implicated in the setting of acute lung damage. This manuscript reviews our current understanding of these endocytic pathways and subsequent intracellular trafficking in various phases of ALI, and also aims to identify potential therapeutic targets for patients with ARDS.
Collapse
Affiliation(s)
- Vitalii Kryvenko
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| | - István Vadász
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| |
Collapse
|
2
|
Alberro-Brage A, Kryvenko V, Malainou C, Günther S, Morty RE, Seeger W, Herold S, Samakovlis C, Vadász I. Influenza virus decreases albumin uptake and megalin expression in alveolar epithelial cells. Front Immunol 2023; 14:1260973. [PMID: 37727782 PMCID: PMC10505651 DOI: 10.3389/fimmu.2023.1260973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 08/17/2023] [Indexed: 09/21/2023] Open
Abstract
Introduction Acute respiratory distress syndrome (ARDS) is a common complication of influenza virus (IV) infection. During ARDS, alveolar protein concentrations often reach 40-90% of plasma levels, causing severe impairment of gas exchange and promoting deleterious alveolar remodeling. Protein clearance from the alveolar space is at least in part facilitated by the multi-ligand receptor megalin through clathrin-mediated endocytosis. Methods To investigate whether IV infection impairs alveolar protein clearance, we examined albumin uptake and megalin expression in MLE-12 cells and alveolar epithelial cells (AEC) from murine precision-cut lung slices (PCLS) and in vivo, under IV infection conditions by flow cytometry and western blot. Transcriptional levels from AEC and broncho-alveolar lavage (BAL) cells were analyzed in an in-vivo mouse model by RNAseq. Results IV significantly downregulated albumin uptake, independently of activation of the TGF-β1/GSK3β axis that has been previously implicated in the regulation of megalin function. Decreased plasma membrane abundance, total protein levels, and mRNA expression of megalin were associated with this phenotype. In IV-infected mice, we identified a significant upregulation of matrix metalloproteinase (MMP)-14 in BAL fluid cells. Furthermore, the inhibition of this protease partially recovered total megalin levels and albumin uptake. Discussion Our results suggest that the previously described MMP-driven shedding mechanisms are potentially involved in downregulation of megalin cell surface abundance and clearance of excess alveolar protein. As lower alveolar edema protein concentrations are associated with better outcomes in respiratory failure, our findings highlight the therapeutic potential of a timely MMP inhibition in the treatment of IV-induced ARDS.
Collapse
Affiliation(s)
- Andrés Alberro-Brage
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| | - Vitalii Kryvenko
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| | - Christina Malainou
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| | - Stefan Günther
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Rory E. Morty
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
- Department of Translational Pulmonology, Heidelberg University Hospital, Heidelberg, Germany
| | - Werner Seeger
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Susanne Herold
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| | - Christos Samakovlis
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - István Vadász
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
- German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| |
Collapse
|
3
|
Kryvenko V, Alberro-Brage A, Fysikopoulos A, Wessendorf M, Tello K, Morty RE, Herold S, Seeger W, Samakovlis C, Vadász I. Clathrin-Mediated Albumin Clearance in Alveolar Epithelial Cells of Murine Precision-Cut Lung Slices. Int J Mol Sci 2023; 24:ijms24032644. [PMID: 36768968 PMCID: PMC9916738 DOI: 10.3390/ijms24032644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 02/03/2023] Open
Abstract
A hallmark of acute respiratory distress syndrome (ARDS) is an accumulation of protein-rich alveolar edema that impairs gas exchange and leads to worse outcomes. Thus, understanding the mechanisms of alveolar albumin clearance is of high clinical relevance. Here, we investigated the mechanisms of the cellular albumin uptake in a three-dimensional culture of precision-cut lung slices (PCLS). We found that up to 60% of PCLS cells incorporated labeled albumin in a time- and concentration-dependent manner, whereas virtually no uptake of labeled dextran was observed. Of note, at a low temperature (4 °C), saturating albumin receptors with unlabeled albumin and an inhibition of clathrin-mediated endocytosis markedly decreased the endocytic uptake of the labeled protein, implicating a receptor-driven internalization process. Importantly, uptake rates of albumin were comparable in alveolar epithelial type I (ATI) and type II (ATII) cells, as assessed in PCLS from a SftpcCreERT2/+: tdTomatoflox/flox mouse strain (defined as EpCAM+CD31-CD45-tdTomatoSPC-T1α+ for ATI and EpCAM+CD31-CD45-tdTomatoSPC+T1α- for ATII cells). Once internalized, albumin was found in the early and recycling endosomes of the alveolar epithelium as well as in endothelial, mesenchymal, and hematopoietic cell populations, which might indicate transcytosis of the protein. In summary, we characterize albumin uptake in alveolar epithelial cells in the complex setting of PCLS. These findings may open new possibilities for pulmonary drug delivery that may improve the outcomes for patients with respiratory failure.
Collapse
Affiliation(s)
- Vitalii Kryvenko
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
| | - Andrés Alberro-Brage
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
| | - Athanasios Fysikopoulos
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
| | - Miriam Wessendorf
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
| | - Khodr Tello
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
| | - Rory E. Morty
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
- Department of Translational Pulmonology, and Translational Lung Research Center (TLRC), 69120 Heidelberg, Germany
| | - Susanne Herold
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
| | - Werner Seeger
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Christos Samakovlis
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - István Vadász
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), 35392 Giessen, Germany
- German Center for Lung Research (DZL), 35392 Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Institute for Lung Health (ILH), 35392 Giessen, Germany
- Correspondence: ; Tel.: +49-641-985-42354; Fax: +49-641-985-42359
| |
Collapse
|
4
|
Sandoval L, Fuentealba LM, Marzolo MP. Participation of OCRL1, and APPL1, in the expression, proteolysis, phosphorylation and endosomal trafficking of megalin: Implications for Lowe Syndrome. Front Cell Dev Biol 2022; 10:911664. [PMID: 36340038 PMCID: PMC9630597 DOI: 10.3389/fcell.2022.911664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
Megalin/LRP2 is the primary multiligand receptor for the re-absorption of low molecular weight proteins in the proximal renal tubule. Its function is significantly dependent on its endosomal trafficking. Megalin recycling from endosomal compartments is altered in an X-linked disease called Lowe Syndrome (LS), caused by mutations in the gene encoding for the phosphatidylinositol 5-phosphatase OCRL1. LS patients show increased low-molecular-weight proteins with reduced levels of megalin ectodomain in the urine and accumulation of the receptor in endosomal compartments of the proximal tubule cells. To gain insight into the deregulation of megalin in the LS condition, we silenced OCRL1 in different cell lines to evaluate megalin expression finding that it is post-transcriptionally regulated. As an indication of megalin proteolysis, we detect the ectodomain of the receptor in the culture media. Remarkably, in OCRL1 silenced cells, megalin ectodomain secretion appeared significantly reduced, according to the observation in the urine of LS patients. Besides, the silencing of APPL1, a Rab5 effector associated with OCRL1 in endocytic vesicles, also reduced the presence of megalin’s ectodomain in the culture media. In both silencing conditions, megalin cell surface levels were significantly decreased. Considering that GSK3ß-mediated megalin phosphorylation reduces receptor recycling, we determined that the endosomal distribution of megalin depends on its phosphorylation status and OCRL1 function. As a physiologic regulator of GSK3ß, we focused on insulin signaling that reduces kinase activity. Accordingly, megalin phosphorylation was significantly reduced by insulin in wild-type cells. Moreover, even though in cells with low activity of OCRL1 the insulin response was reduced, the phosphorylation of megalin was significantly decreased and the receptor at the cell surface increased, suggesting a protective role of insulin in a LS cellular model.
Collapse
Affiliation(s)
- Lisette Sandoval
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Luz M. Fuentealba
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - María-Paz Marzolo
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- *Correspondence: María-Paz Marzolo,
| |
Collapse
|
5
|
Potential therapeutic effects of interleukin-35 on the differentiation of naïve T cells into Helios +Foxp3 + Tregs in clinical and experimental acute respiratory distress syndrome. Mol Immunol 2021; 132:236-249. [PMID: 33494935 PMCID: PMC8058740 DOI: 10.1016/j.molimm.2021.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 01/02/2021] [Accepted: 01/05/2021] [Indexed: 12/12/2022]
Abstract
Regulatory T lymphocytes are important targets for the treatment of acute respiratory distress syndrome (ARDS). IL-35 is a newly identified IL-12 cytokine family member that plays an important protective role in a variety of immune system diseases by regulating Treg cell differentiation; however, the role of IL-35 in the pathogenesis of ARDS is still unclear. Here, we found that IL-35 was significantly elevated in adult patients with ARDS compared to controls. Additionally, IL-35 was positively and significantly correlated with IL-6, IL-10 and the oxygenation index (PaO2/FiO2 ratio) but negatively correlated with TNF-α, IL-1β and APACHE II score during ARDS. Moreover, the proportion of Treg/CD4+ cells in the peripheral blood of ARDS patients and the expression of NF-κB in PMBCs were significantly higher than in healthy individuals. Recombinant IL-35 improved survival in a murine model of CLP-induced ARDS. Additionally, IL-35 administration decreased the inflammatory response, as reflected by lower levels of cytokines (including IL-2, TNF-α, IL-1β and IL-6) and less lung damage in CLP-induced ARDS. Furthermore, recombinant IL-35 reduced the apoptosis of lung tissue and the expression of NF-κB signalling in a CLP-induced ARDS model and increased the proportion of Treg cells in spleen and peripheral blood. In vitro experiments revealed that IL-35 can affect the phosphorylation of STAT5 during differentiation of naïve CD4+ T lymphocytes into Foxp3+Helios+ Tregs. Our findings suggest that IL-35 attenuates ARDS by promoting the differentiation of naïve CD4+ T cells into Foxp3+Helios+ Tregs, thereby providing a novel tool for anti-ARDS therapy.
Collapse
|
6
|
Cabezas F, Farfán P, Marzolo MP. Participation of the SMAD2/3 signalling pathway in the down regulation of megalin/LRP2 by transforming growth factor beta (TGF-ß1). PLoS One 2019; 14:e0213127. [PMID: 31120873 PMCID: PMC6532859 DOI: 10.1371/journal.pone.0213127] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/08/2019] [Indexed: 12/19/2022] Open
Abstract
Megalin/LRP2 is a receptor that plays important roles in the physiology of several organs, such as kidney, lung, intestine, and gallbladder and also in the physiology of the nervous system. Megalin expression is reduced in diseases associated with fibrosis, including diabetic nephropathy, hepatic fibrosis and cholelithiasis, as well as in some breast and prostate cancers. One of the hallmarks of these conditions is the presence of the cytokine transforming growth factor beta (TGF-ß). Although TGF-ß has been implicated in the reduction of megalin levels, the molecular mechanism underlying this regulation is not well understood. Here, we show that treatment of two epithelial cell lines (from kidney and gallbladder) with TGF-ß1 is associated with decreased megalin mRNA and protein levels, and that these effects are reversed by inhibiting the TGF-ß1 type I receptor (TGF-ßRI). Based on in silico analyses, the two SMAD-binding elements (SBEs) in the megalin promoter are located at positions -57 and -605. Site-directed mutagenesis of the SBEs and chromatin immunoprecipitation (ChIP) experiments revealed that SMAD2/3 transcription factors interact with SBEs. Both the presence of SMAD2/3 and intact SBEs were associated with repression of the megalin promoter, in the absence as well in the presence of TGF-ß1. Also, reduced megalin expression and promoter activation triggered by high concentration of albumin are dependent on the expression of SMAD2/3. Interestingly, the histone deacetylase inhibitor Trichostatin A (TSA), which induces megalin expression, reduced the effects of TGF-ß1 on megalin mRNA levels. These data show the significance of TGF-ß and the SMAD2/3 signalling pathway in the regulation of megalin and explain the decreased megalin levels observed under conditions in which TGF-ß is upregulated, including fibrosis-associated diseases and cancer.
Collapse
Affiliation(s)
- Felipe Cabezas
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pamela Farfán
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - María-Paz Marzolo
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- * E-mail:
| |
Collapse
|
7
|
Kryvenko V, Vadász I. The role of CD36 in endothelial albumin transcytosis. Am J Physiol Lung Cell Mol Physiol 2019; 316:L738-L739. [PMID: 30840484 DOI: 10.1152/ajplung.00104.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Vitalii Kryvenko
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, German Center for Lung Research , Giessen , Germany.,The Cardio-Pulmonary Institute , Giessen , Germany
| | - István Vadász
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, German Center for Lung Research , Giessen , Germany.,The Cardio-Pulmonary Institute , Giessen , Germany
| |
Collapse
|
8
|
Peruchetti DDB, Silva-Aguiar RP, Siqueira GM, Dias WB, Caruso-Neves C. High glucose reduces megalin-mediated albumin endocytosis in renal proximal tubule cells through protein kinase B O-GlcNAcylation. J Biol Chem 2018; 293:11388-11400. [PMID: 29871929 DOI: 10.1074/jbc.ra117.001337] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 05/02/2018] [Indexed: 01/09/2023] Open
Abstract
The role of albumin reabsorption in proximal tubule (PT) cells has emerged as an important factor in the genesis of albuminuria observed in the early stages of diabetes. Evidence has shown that a decrease in megalin expression could be the key mechanism in this process. In the present work, we investigated the molecular mechanism underlying the modulation of albumin endocytosis in LLC-PK1 cells, a model of PT cells. High glucose concentrations (HG) inhibited megalin expression and albumin endocytosis after 48 h of incubation. This inhibitory effect involves the entrance of glucose into PT cells through SGLT located at the luminal membrane. Once inside PT cells, glucose is diverted to the hexosamine biosynthetic pathway (HBP) increasing O-GlcNAcylation of several intracellular proteins, including PKB. This process promotes the inhibition of PKB activity measured by its phosphorylation at Thr-308 and Ser-473 and phosphorylation of specific substrates, glycogen synthase kinase 3β (GSK3β) and tuberous sclerosis complex 2. The decrease in PKB activity led to a decrease in megalin expression and, consequently, reducing albumin endocytosis in LLC-PK1 cells. HG did not change mammalian target of rapamycin (mTOR) C2 activity, responsible for phosphorylated PKB at Ser-473. In addition, HG activated the mTORC1/S6K pathway, but this effect was not correlated to the decrease in megalin expression or albumin endocytosis. Taken together, our data help to clarify the current understanding underlying the genesis of tubular albuminuria induced by hyperglycemia in the early stage of diabetes pathogenesis.
Collapse
Affiliation(s)
- Diogo de Barros Peruchetti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-9042
| | | | - Gabriela Marques Siqueira
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-9042
| | - Wagner Barbosa Dias
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-9042
| | - Celso Caruso-Neves
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-9042; Instituto Nacional de Ciência e Tecnologia em Medicina Regenerativa, INCT-Regenera, Rio de Janeiro, 21941-902, Brazil.
| |
Collapse
|