TFEB-mediated lysosomal exocytosis alleviates high-fat diet–induced lipotoxicity in the kidney
Jun Nakamura, Takeshi Yamamoto, Yoshitsugu Takabatake, Tomoko Namba-Hamano, Satoshi Minami, Atsushi Takahashi, Jun Matsuda, Shinsuke Sakai, Hiroaki Yonishi, Shihomi Maeda, Sho Matsui, Isao Matsui, Takayuki Hamano, Masatomo Takahashi, Maiko Goto, Yoshihiro Izumi, Takeshi Bamba, Miwa Sasai, Masahiro Yamamoto, Taiji Matsusaka, Fumio Niimura, Motoko Yanagita, Shuhei Nakamura, Tamotsu Yoshimori, Andrea Ballabio, Yoshitaka Isaka
Jun Nakamura, Takeshi Yamamoto, Yoshitsugu Takabatake, Tomoko Namba-Hamano, Satoshi Minami, Atsushi Takahashi, Jun Matsuda, Shinsuke Sakai, Hiroaki Yonishi, Shihomi Maeda, Sho Matsui, Isao Matsui, Takayuki Hamano, Masatomo Takahashi, Maiko Goto, Yoshihiro Izumi, Takeshi Bamba, Miwa Sasai, Masahiro Yamamoto, Taiji Matsusaka, Fumio Niimura, Motoko Yanagita, Shuhei Nakamura, Tamotsu Yoshimori, Andrea Ballabio, Yoshitaka Isaka
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Research Article Metabolism Nephrology

TFEB-mediated lysosomal exocytosis alleviates high-fat diet–induced lipotoxicity in the kidney

Abstract

Obesity is a major risk factor for end-stage kidney disease. We previously found that lysosomal dysfunction and impaired autophagic flux contribute to lipotoxicity in obesity-related kidney disease, in both humans and experimental animal models. However, the regulatory factors involved in countering renal lipotoxicity are largely unknown. Here, we found that palmitic acid strongly promoted dephosphorylation and nuclear translocation of transcription factor EB (TFEB) by inhibiting the mechanistic target of rapamycin kinase complex 1 pathway in a Rag GTPase–dependent manner, though these effects gradually diminished after extended treatment. We then investigated the role of TFEB in the pathogenesis of obesity-related kidney disease. Proximal tubular epithelial cell–specific (PTEC-specific) Tfeb-deficient mice fed a high-fat diet (HFD) exhibited greater phospholipid accumulation in enlarged lysosomes, which manifested as multilamellar bodies (MLBs). Activated TFEB mediated lysosomal exocytosis of phospholipids, which helped reduce MLB accumulation in PTECs. Furthermore, HFD-fed, PTEC-specific Tfeb-deficient mice showed autophagic stagnation and exacerbated injury upon renal ischemia/reperfusion. Finally, higher body mass index was associated with increased vacuolation and decreased nuclear TFEB in the proximal tubules of patients with chronic kidney disease. These results indicate a critical role of TFEB-mediated lysosomal exocytosis in counteracting renal lipotoxicity.

Authors

Jun Nakamura, Takeshi Yamamoto, Yoshitsugu Takabatake, Tomoko Namba-Hamano, Satoshi Minami, Atsushi Takahashi, Jun Matsuda, Shinsuke Sakai, Hiroaki Yonishi, Shihomi Maeda, Sho Matsui, Isao Matsui, Takayuki Hamano, Masatomo Takahashi, Maiko Goto, Yoshihiro Izumi, Takeshi Bamba, Miwa Sasai, Masahiro Yamamoto, Taiji Matsusaka, Fumio Niimura, Motoko Yanagita, Shuhei Nakamura, Tamotsu Yoshimori, Andrea Ballabio, Yoshitaka Isaka

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Figure 7

TFEB deficiency stagnates autophagic flux and enhances vulnerability to ischemia/reperfusion injury during HFD treatment.

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TFEB deficiency stagnates autophagic flux and enhances vulnerability to ...
(A) Autophagic flux was assessed by counting the number of GFP-positive dots in the proximal tubules of nonobese or obese GFP-MAP1LC3 transgenic Tfebfl/fl or Tfebfl/fl KAP mice with or without chloroquine administration (n = 3–6 in the nonobese group and 6–8 in the obese group). The number of GFP-positive dots per proximal tubule under each condition was counted in at least 10 high-power fields (original magnification, ×600) (each high-power field contained 10–15 proximal tubules). Representative images are presented. (B and C) Representative images of PAS (B) and TUNEL (C) staining of the kidney cortical regions of nonobese and obese Tfebfl/fl or Tfebfl/fl KAP mice 2 days after unilateral IR or sham operation (n = 6–8 in each group). Sections were immunostained for LRP2, a marker of proximal tubules (blue) (A) and counterstained with DAPI (A) and methyl green (blue/green) (C). (B) The tubular injury score is shown. (C) The number of TUNEL-positive PTECs was calculated in at least 10 high-power fields. Bars: 10 μm (A), 500 μm (B), and 100 μm (C). Data are provided as means ± SEM. Statistically significant differences: *P < 0.05 versus mice with no chloroquine treatment; #P < 0.05 versus nonobese mice (A, 2-tailed Student’s t test; B and C, 1-way ANOVA followed by the Tukey-Kramer test). Arrows indicate GFP-MAP1LC3 dots. CQ, chloroquine; F/F, Tfebfl/fl mice; F/F;KAP, Tfebfl/fl KAP mice.