Renal tubule Cpt1a overexpression protects from kidney fibrosis by restoring mitochondrial homeostasis
Verónica Miguel, Jessica Tituaña, J. Ignacio Herrero, Laura Herrero, Dolors Serra, Paula Cuevas, Coral Barbas, Diego Rodríguez Puyol, Laura Márquez-Expósito, Marta Ruiz-Ortega, Carolina Castillo, Xin Sheng, Katalin Susztak, Miguel Ruiz-Canela, Jordi Salas-Salvadó, Miguel A. Martínez González, Sagrario Ortega, Ricardo Ramos, Santiago Lamas
Verónica Miguel, Jessica Tituaña, J. Ignacio Herrero, Laura Herrero, Dolors Serra, Paula Cuevas, Coral Barbas, Diego Rodríguez Puyol, Laura Márquez-Expósito, Marta Ruiz-Ortega, Carolina Castillo, Xin Sheng, Katalin Susztak, Miguel Ruiz-Canela, Jordi Salas-Salvadó, Miguel A. Martínez González, Sagrario Ortega, Ricardo Ramos, Santiago Lamas
View: Text | PDF
Research Article Nephrology

Renal tubule Cpt1a overexpression protects from kidney fibrosis by restoring mitochondrial homeostasis

Abstract

Chronic kidney disease (CKD) remains a major epidemiological, clinical, and biomedical challenge. During CKD, renal tubular epithelial cells (TECs) present a persistent inflammatory and profibrotic response. Fatty acid oxidation (FAO), the main source of energy for TECs, is reduced in kidney fibrosis and contributes to its pathogenesis. To determine whether gain of function in FAO (FAO-GOF) could protect from fibrosis, we generated a conditional transgenic mouse model with overexpression of the fatty acid shuttling enzyme carnitine palmitoyl-transferase 1A (CPT1A) in TECs. Cpt1a-knockin (CPT1A-KI) mice subjected to 3 models of renal fibrosis (unilateral ureteral obstruction, folic acid nephropathy [FAN], and adenine-induced nephrotoxicity) exhibited decreased expression of fibrotic markers, a blunted proinflammatory response, and reduced epithelial cell damage and macrophage influx. Protection from fibrosis was also observed when Cpt1a overexpression was induced after FAN. FAO-GOF restored oxidative metabolism and mitochondrial number and enhanced bioenergetics, increasing palmitate oxidation and ATP levels, changes that were also recapitulated in TECs exposed to profibrotic stimuli. Studies in patients showed decreased CPT1 levels and increased accumulation of short- and middle-chain acylcarnitines, reflecting impaired FAO in human CKD. We propose that strategies based on FAO-GOF may constitute powerful alternatives to combat fibrosis inherent to CKD.

Authors

Verónica Miguel, Jessica Tituaña, J. Ignacio Herrero, Laura Herrero, Dolors Serra, Paula Cuevas, Coral Barbas, Diego Rodríguez Puyol, Laura Márquez-Expósito, Marta Ruiz-Ortega, Carolina Castillo, Xin Sheng, Katalin Susztak, Miguel Ruiz-Canela, Jordi Salas-Salvadó, Miguel A. Martínez González, Sagrario Ortega, Ricardo Ramos, Santiago Lamas

×

Figure 6

CPT1A overexpression reduces epithelial cell damage in the FAN model.

Options: View larger image (or click on image) Download as PowerPoint
CPT1A overexpression reduces epithelial cell damage in the FAN model. (A...
(A) Representative flow cytometry dot plots from obstructed kidneys of WT and Pax8-CPT1A mice subjected to FAN after doxycycline treatment. Cells were gated for CD45 negative/epithelial cell adhesion molecule (EpCAM) positive (upper panels) and selected for the presence of CD24 (lower panels). Numbers in quadrants indicate cell proportions. (B) Bar graphs show the percentage of kidney cells positive for CD24. Data represent the mean ± SEM (n = 4 mice). *P < 0.05 compared with their corresponding control (CT) kidneys; #P < 0.05 compared with damaged kidneys in WT mice. (C and D) Representative immunoblots and densitometries corresponding to CPT1A and phosphorylated RIPK3 protein levels in kidneys as in A (n = 3 mice). *P < 0.05, **P < 0.01 compared with their corresponding CT kidneys; #P < 0.05, ##P < 0.01 compared with kidneys from WT mice with the same experimental condition. (E) mRNA levels of RIPK1, RIPK3, and MLKL were determined by qRT-PCR in kidneys as in A. Bar graphs represent the mean ± SEM of fold changes (n = 6 mice). ***P < 0.001 compared with their corresponding CT kidneys; ##P < 0.01 compared with kidneys from WT mice with the same experimental condition. (F) mRNA levels of apoptosis-associated genes were determined by qRT-PCR using TaqMan qPCR probes in kidneys from CT and FA-treated (FAN) WT and Pax8-CPT1A mice after doxycycline induction. Bar graphs represent the mean ± SEM of fold changes (n = 6 mice). *P < 0.05, **P < 0.01 compared with their CT kidneys; ##P < 0.05 compared with kidneys from WT mice with the same experimental condition. Statistical significance between 2 independent groups was determined using nonparametric 2-tailed Kruskal-Wallis test. For detailed gene nomenclature, see Supplemental Table 4.