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. 2019 Jan 1;28(1):143-154.
doi: 10.1093/hmg/ddy343.

Bezafibrate induces autophagy and improves hepatic lipid metabolism in glycogen storage disease type Ia

Lauren R Waskowicz  1 , Jin Zhou  2 , Dustin J Landau  1 , Elizabeth D Brooks  1   3 , Andrea Lim  2 , Zollie A Yavarow  1 , Tsubasa Kudo  4 , Haoyue Zhang  1 , Yajun Wu  5 , Stuart Grant  6 , Sarah P Young  1 , Bay Boon Huat  5 , Paul M Yen  2   7 , Dwight D Koeberl  1   8
Affiliations

Bezafibrate induces autophagy and improves hepatic lipid metabolism in glycogen storage disease type Ia

Lauren R Waskowicz et al. Hum Mol Genet. .

Abstract

Glucose-6-phosphatase α (G6Pase) deficiency, also known as von Gierke's Disease or Glycogen storage disease type Ia (GSD Ia), is characterized by decreased ability of the liver to convert glucose-6-phosphate to glucose leading to glycogen accumulation and hepatosteatosis. Long-term complications of GSD Ia include hepatic adenomas and carcinomas, in association with the suppression of autophagy in the liver. The G6pc-/- mouse and canine models for GSD Ia were treated with the pan-peroxisomal proliferator-activated receptor agonist, bezafibrate, to determine the drug's effect on liver metabolism and function. Hepatic glycogen and triglyceride concentrations were measured and western blotting was performed to investigate pathways affected by the treatment. Bezafibrate decreased liver triglyceride and glycogen concentrations and partially reversed the autophagy defect previously demonstrated in GSD Ia models. Changes in medium-chain acyl-CoA dehydrogenase expression and acylcarnintine flux suggested that fatty acid oxidation was increased and fatty acid synthase expression associated with lipogenesis was decreased in G6pc-/- mice treated with bezafibrate. In summary, bezafibrate induced autophagy in the liver while increasing fatty acid oxidation and decreasing lipogenesis in G6pc-/- mice. It represents a potential therapy for glycogen overload and hepatosteatosis associated with GSD Ia, with beneficial effects that have implications for non-alcoholic fatty liver disease.

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Figures

Figure 1
Figure 1
Bezafibrate treatment decreased triglycerides and glycogen in G6pc−/− mice liver. (A) Triglyceride concentration significantly decreased in livers of G6pc−/− mice treated with bezafibrate compared with the livers in vehicle treated controls. (B) Average liver glycogen concentration decreased in G6pc−/− mice treated with bezafibrate; however, the change was not significant. (C–D) H&E staining and ORO staining qualitatively verify lowering of liver triglycerides in liver tissue and normalization of cellular structure. Group sizes are WT + Vehicle n = 3, WT + Bezafibrate n = 4, G6pc−/− + Vehicle n = 3, G6pc−/− + Bezafibrate n = 4. Mean +/− s.d. shown. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 from ANOVA (A) or Kruskal–Wallis testing (B).
Figure 2
Figure 2
Bezafibrate treatment induced autophagic flux in G6pc−/− mice liver. (A) Western blotting of LC3-II, a protein recruited to autophagosomes during autophagy induction, showed significantly increased protein expression in both G6pc−/− and WT mice treated with bezafibrate. Expression levels of p62, a protein dependent on autophagy for degradation, were decreased in G6pc−/− mice treated with bezafibrate compared with vehicle treated controls. (B) Protein expression of phosphorylated AMPK (activated) relative to AMPK expression was higher in bezafibrate treated mice. (C) ATGL, a target for AMPK phosphorylation. Group sizes are WT + Vehicle n = 3, WT + Bezafibrate n = 4, G6pc−/− + Vehicle n = 3, G6pc−/− + Bezafibrate n = 4. Mean +/− s.d. shown. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 from ANOVA (A,C) or Kruskal–Wallis testing (B). (C) EM showing livers obtained from WT, G6pc−/−, bezafibrate treated G6pc−/− mice. L: lipid droplet; G: Glycogen; AP: autophagosome; AL: autolysosomes.
Figure 3
Figure 3
Bezafibrate treatment improved mitochondrial biogenesis and ultra-structure in G6pc−/− mice liver. (A–C) Western blot and densitometric analysis of (A) PGC1α, (B) COXIV and (C) TOMM20. Bezafibrate treatment increased the protein level of PGC1α, COXIV and TOMM20 in G6pc−/− mouse liver. (D) Mitochondrial DNA was significantly increased in livers of G6pc−/− mice treated with bezafibrate. Group sizes are; WT + Vehicle n = 3, WT + Bezafibrate n = 4, G6pc−/− + Vehicle n = 3, G6pc−/− + Bezafibrate n = 4. Data are shown as Mean ± s.d. shown. *P< 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 from ANOVA (B, C, D) and Kruskal–Wallis testing (A). (E) Electron microscopy images showing the mitochondrial ultra-structure in the liver from WT, G6pc−/− and bezafibrate treated G6pc−/− mice.
Figure 4
Figure 4
Bezafibrate treatment improves lipid metabolism in G6pc−/− mice liver. (A) Medium chain acylCoA dehydrogenase (MCAD) and (B) acylCoA oxidase (ACOX) are essential for mitochondrial and peroxisomal fatty acid oxidation (respectively). Both enzymes showed increased protein expression in the livers of mice treated with bezafibrate compared with vehicle-treated controls. (C) FAS levels were normalized to within WT levels in G6pc−/− livers treated with bezafibrate and (D) PPAR-α protein expression was increased 4-fold in G6pc−/− mouse livers compared with vehicle treated controls. (E) Liver PPAR mRNA levels were not significantly affected by bezafibrate treatment, however, there were differences between levels in WT and G6pc−/− mice. (F) Total acylcarnitines were significantly decreased in plasma from mice treated with bezafibrate. †Significant difference between G6pc−/-WT + Vehicle and G6pc−/− + Bezafibrate, *Significant difference between G6pc−/− + Bezafibrate and G6pc−/− + Vehicle, #Significant difference between G6pc−/− + Vehicle and wild-type (WT) + Vehicle. Group sizes are; WT + Vehicle n = 3, WT + Bezafibrate n = 4, G6pc−/− + Vehicle n = 3, G6pc−/− + Bezafibrate n = 4. G6pc−/−Mean +/− s.d. shown. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 from ANOVA (A, C, D, E, F) and Kruskal–Wallis testing (B).
Figure 5
Figure 5
Longer term bezafibrate administration in G6pc−/− mice. (A)G6pc−/− mice treated for 10 days with bezafibrate showed higher mortality. (B) Liver triglyceride concentration decreased in G6pc−/− mice treated with bezafibrate, however, average liver glycogen concentration (C) increased compared with vehicle treated controls. (D) Bezafibrate treatment significantly decreased plasma triglyceride concentration in G6pc−/− mice and produced measurable levels of blood glucose (E) compared with vehicle treated controls (glucose levels below lower detection limit for glucometer). (F) Acadm mRNA levels were elevated in G6pc−/− mice livers treated with bezafibrate. Group sizes are WT + Vehicle n = 5, WT + Bezafibrate n = 5, G6pc−/− + Vehicle n = 6, G6pc−/− + Bezafibrate n = 6. Mean +/− s.d. shown. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 from ANOVA (E, F) and Kruskal–Wallis testing (B, C, D).
Figure 6
Figure 6
Effects of bezafibrate on GSD Ia dogs. (A) Hepatic ultrasound revealed a 1.68 × 1.62 cm mass at baseline in one GSD Ia dog. (B) Hepatic ultrasound after 1.2 months of bezafibrate treatment showed a hepatic mass had decreased in size to 1.47 × 0.85 cm and could not be detected after 3.6 months of bezafibrate treatment. (C) Ability to fast increased from baseline to 2.4 months after bezafibrate treatment as shown with the AUC of 8 h of fasting with blood draws every 2 h. (D) ALT decreased from baseline over 2.4 months of treatment. (n = 3) Mean ± SD shown. *P < 0.05 for one-tailed, paired t-test. Dotted lines show normal range for AUC and ALT.
Figure 7
Figure 7
Bezafibrate effect through activation of PPARα. Bezafibrate treatments targets nuclear receptor PPARα (expressed primarily in liver and brain) to induce fatty acid oxidation and autophagy and reduce fat storage through lipogenesis. These processes increase lipid metabolism, reduce glycogen accumulation and work to normalize liver tissue. Because hepatosteatosis and autophagy deficit add to the risk of GSD Ia patients developing HCA and HCC, addressing these cellular abnormalities can potentially help reduce the chance of negative, long term complications. Autophagy induction also has the potential to address hypoglycemia by circumventing G6Pase via glycogen cycling and glycogenolysis.
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References

    1. Lei K.-J., Chen H., Pan C.-J., Ward J.M., Mosinger B. Jr., Lee E.J., Westphal H., Mansfield B.C. and Chou J.Y. (1996) Glucose–6–phosphatase dependent substrate transport in the glycogen storage disease type–1a mouse. Nat. Genet., 13, 203–209. - PubMed
    1. Bechmann L.P., Hannivoort R.A., Gerken G., Hotamisligil G.S., Trauner M. and Canbay A. (2012) The interaction of hepatic lipid and glucose metabolism in liver diseases. J. Hepatol., 56, 952–964. - PubMed
    1. Froissart R., Piraud M., Boudjemline A.M., Vianey-Saban C., Petit F., Hubert-Buron A., Eberschweiler P.T., Gajdos V. and Labrune P. (2011) Glucose-6-phosphatase deficiency. Orphanet J. Rare Dis., 6, 27. - PMC - PubMed
    1. Kishnani P.S., Austin S.L., Abdenur J.E., Arn P., Bali D.S., Boney A., Chung W.K., Dagli A.I., Dale D., Koeberl D. et al. (2014) Diagnosis and management of glycogen storage disease type I: a practice guideline of the American College of Medical Genetics and Genomics. Genet. Med., 16, e1. - PubMed
    1. Franco L.M., Krishnamurthy V., Bali D., Weinstein D.A., Arn P., Clary B., Boney A., Sullivan J., Frush D.P., Chen Y.T. et al. (2005) Hepatocellular carcinoma in glycogen storage disease type Ia: a case series. J. Inher. Metab. Dis., 28, 153–162. - PubMed

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