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Pfeffer T, Krug SM, Kracke T, Schürfeld R, Colbatzky F, Kirschner P, Medert R, Freichel M, Schumacher D, Bartosova M, Zarogiannis SG, Muckenthaler MU, Altamura S, Pezer S, Volk N, Schwab C, Duensing S, Fleming T, Heidenreich E, Zschocke J, Hell R, Poschet G, Schmitt CP, Peters V. Knock-out of dipeptidase CN2 in human proximal tubular cells disrupts dipeptide and amino acid homeostasis and para- and transcellular solute transport. Acta Physiol (Oxf) 2024; 240:e14126. [PMID: 38517248 DOI: 10.1111/apha.14126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/23/2024]
Abstract
AIM Although of potential biomedical relevance, dipeptide metabolism has hardly been studied. We found the dipeptidase carnosinase-2 (CN2) to be abundant in human proximal tubules, which regulate water and solute homeostasis. We therefore hypothesized, that CN2 has a key metabolic role, impacting proximal tubular transport function. METHODS A knockout of the CN2 gene (CNDP2-KO) was generated in human proximal tubule cells and characterized by metabolomics, RNA-seq analysis, paracellular permeability analysis and ion transport. RESULTS CNDP2-KO in human proximal tubule cells resulted in the accumulation of cellular dipeptides, reduction of amino acids and imbalance of related metabolic pathways, and of energy supply. RNA-seq analyses indicated altered protein metabolism and ion transport. Detailed functional studies demonstrated lower CNDP2-KO cell viability and proliferation, and altered ion and macromolecule transport via trans- and paracellular pathways. Regulatory and transport protein abundance was disturbed, either as a consequence of the metabolic imbalance or the resulting functional disequilibrium. CONCLUSION CN2 function has a major impact on intracellular amino acid and dipeptide metabolism and is essential for key metabolic and regulatory functions of proximal tubular cells. These findings deserve in vivo analysis of the relevance of CN2 for nephron function and regulation of body homeostasis.
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Affiliation(s)
- Tilman Pfeffer
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
- Tissue Bank of the German Center for Infection Research (DZIF), Partner Site Heidelberg, Institute of Pathology, Heidelberg University Hospital, Heidelberg, Germany
| | - Susanne M Krug
- Clinical Physiology/Nutritional Medicine, Charité-Universitätsmedizin Berlin, CBF, Berlin, Germany
| | - Tamara Kracke
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Robin Schürfeld
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Florian Colbatzky
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Philip Kirschner
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Rebekka Medert
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Marc Freichel
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Dagmar Schumacher
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Maria Bartosova
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Sotiris G Zarogiannis
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Martina U Muckenthaler
- Department of Pediatric Oncology, Hematology and Immunology and Hopp Children Cancer Center (KiTZ), University Hospital Heidelberg, Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), EMBL and University of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Heidelberg, Germany
| | - Sandro Altamura
- Department of Pediatric Oncology, Hematology and Immunology and Hopp Children Cancer Center (KiTZ), University Hospital Heidelberg, Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), EMBL and University of Heidelberg, Heidelberg, Germany
| | - Silvia Pezer
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Nadine Volk
- Tissue Bank of the National Center for Tumor Diseases (NCT), Heidelberg, Germany
| | - Constantin Schwab
- Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - Stefan Duensing
- Department of Urology, University Hospital Heidelberg and National Center for Tumor Diseases (NCT) Heidelberg, Heidelberg, Germany
| | - Thomas Fleming
- Internal Medicine I and Clinical Chemistry, University Hospital Heidelberg, Heidelberg, Germany
| | - Elena Heidenreich
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Johannes Zschocke
- Institute of Human Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Rüdiger Hell
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Gernot Poschet
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Claus P Schmitt
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Verena Peters
- Medical Faculty Heidelberg, Center for Pediatric and Adolescent Medicine, Department I, Division of Pediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
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Zarantonello D, Brunori G. The Role of Plant-Based Diets in Preventing and Mitigating Chronic Kidney Disease: More Light than Shadows. J Clin Med 2023; 12:6137. [PMID: 37834781 PMCID: PMC10573653 DOI: 10.3390/jcm12196137] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/16/2023] [Accepted: 09/08/2023] [Indexed: 10/15/2023] Open
Abstract
Chronic kidney disease (CKD) is a non-communicable disease that affects >10% of the general population worldwide; the number of patients affected by CKD is increasing due in part to the rise in risk factors such as obesity, hypertension, and diabetes mellitus. As many studies show, diet can be an important tool for preventing and mitigating the onset of non-communicable diseases. Plant-based diets (PBDs) are those that emphasize the consumption of plant foods and may or may not include small or moderate amounts of animal foods. Recently, these diets have received increasing interest because they have been associated with favourable effects on health and also appear to protect against the development and progression of CKD. PBDs, which are associated with protein restrictions, seem to offer adjunctive advantages in patients with chronic kidney disease, as compared to conventional low-protein diets that include animal proteins. The principal aims of this review are to provide a comprehensive overview of the existing literature regarding the role of plant-based diets and low-protein, plant-based diets in the context of chronic kidney disease. Moreover, we try to clarify the definition of plant-based diets, and then we analyse possible concerns about the use of PBDs in patients with chronic kidney disease (nutritional deficiency and hyperkalaemia risk). Finally, we offer some strategies to increase the nutritional value of plant-based low-protein diets. In the Materials and Methods section, many studies about plant-based diets and low-protein plant-based diets (e.g., the very-low-protein diet and vegan low-protein diet, LPD) in chronic kidney disease were considered. In the Results and Conclusion section, current data, most from observational studies, agree upon the protective effect of plant-based diets on kidney function. Moreover, in patients with advanced CKD, low-protein plant-based options, especially a very-low-protein diet supplemented with heteroanalogues (VLPDs), compared to a conventional LPD appear to offer adjunctive advances in terms of delaying dialysis and mitigating metabolic disturbances. However, further studies are necessary to better investigate the possible metabolic and cardiovascular advantages of plant-based LPDs versus conventional LPDs.
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Affiliation(s)
- Diana Zarantonello
- Department of Nephrology, Santa Chiara Hospital, APSS, 38122 Trento, Italy;
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