Background. Obesity is usually associated with white adipose tissue dysfunction which finally impairs non-adipose tissues. Kidneys are affected by this process leading to chronic kidney disease. This disease is characterized by proximal tubular epithelial cells (PTECs) lipotoxicity and dysfunction associated with decreased AMPK activity, alteration of the autophagic flux and mitochondrial dysfunction. These events were demonstrated on basic model of lipotoxicity using saturated fatty acids (FAs). However, several studies suggested that these features might be dependent on the FAs type suggesting that the lipotoxic phenotype might be influenced by the nature of FAs. Aims. In this regard, the first aim of this work was to characterize the effects of different types of FAs, such as palmitic acid (PA), oleic acid (OA) and docosahexaenoic acid (DHA), alone or in combinations on lipid droplets (LDs) accumulation, on autophagic flux and on LDs interactions with organelles in PTECs. The second objective was to characterize the effects of these FAs on the AMPK activity and to assess its putative role in the alterations of autophagic flux induced by PA. Methods. Primary mouse PTECs were treated for 24 h with BSA, PA, OA and DHA or combinations. To compare effects of the different FAs, identical concentrations (100 and 300 ?M) of each FA were first tested. Second, physiological concentrations (150 or 300 ?M PA or OA and 25 or 50 ?M of DHA) were assessed. Results. An increased in the accumulation of LDs was observed in cells treated for 24 h with FAs especially with OA, when compared to BSA, PA and DHA. Besides, markers of autophagosome accumulation and formation, respectively, p62 and LC3-II/ -I ratio were increased in cells treated with PA for 24 h when compared to other conditions. In addition, changes in the abundance of these markers were normalized in cells incubated with PA in combination with OA or DHA. Moreover, cells treated with PA for 24 h displayed decreased AMPK activity when compared to cells exposed to OA, DHA or combinations. Finally, the different FAs seemed to slightly decrease the interactions between LDs and lysosomes or mitochondria. Conclusions. Even if all FAs induced LD accumulation in mPTEC, the autophagic flux was only inhibited by PA which correlated with decreased AMPK activity. Indeed, OA and DHA conferred protection against the inhibition of autophagic flux and AMPK activity induced by PA. Nevertheless, future work is needed to assess the causal link between the inhibition of AMPK by PA and the alterations of autophagy.
Date of Award | 28 Dec 2022 |
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Original language | English |
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Awarding Institution | |
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Supervisor | Thierry Arnould (Supervisor) |
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- fatty acids
- autophagy
- lipotoxicity
- proximal tubular epithelial cells
- AMP
- activated protein kinase
Study of AMPK and autophagic alterations induced by fatty acids in murine renal proximal tubular epithelial cells
Denis, A. (Author). 28 Dec 2022
Student thesis: Master types › Master in Biomedecine, professional focus in preclinical research