Fatty Liver Disease Linked to Impaired Mitochondrial Function

A recent study published in the Laboratory Investigation journal sheds light on the link between fatty liver disease and impaired mitochondrial function. Researchers in Rehovot, Israel, found that mice fed a choline-deficient, ethionine-supplemented diet developed fatty liver disease, characterized by accumulation of fat vacuoles in hepatocytes and decreased mitochondrial levels. The study revealed impaired activity of PPAR-?-coactivator 1a (PGC1a), a key regulator of mitochondrial biogenesis, in mice with fatty liver disease. This impairment was associated with decreased interaction of PGC1a with promoters containing NRF-1 and NRF-2 response elements and reduced activation of the gluconeogenic gene phosphoenol-pyruvate carboxykinase.

Key Takeaways:

• Mice fed a choline-deficient, ethionine-supplemented diet developed fatty liver disease with up to 90% of hepatocytes accumulating fat vacuoles.
• Decreased mitochondrial levels and increased superoxide radicals' levels were observed in livers of CDE-fed mice.
• PGC1a protein levels were reduced in CDE-treated mice, while PGC1a mRNA levels increased significantly.
• Impaired activity of PGC1a was confirmed by chromatin immunoprecipitation analysis, showing decreased interaction with promoters containing NRF-1 and NRF-2 response elements.
• Mitochondrial biogenesis genes nuclear respiratory factor 1 (NRF-1), mitochondrial transcription factor A (TFAM), and others remained unchanged in fasted CDE-treated mice.
• The study demonstrated, for the first time, that attenuated mitochondrial biogenesis in steatotic livers is associated with impaired biological activity of PGC1a.
• The researchers observed a decrease in PGC1a ability to activate the expression of the gluconeogenic gene phosphoenol-pyruvate carboxykinase.
• M. Aharoni-Simon and colleagues published their study in Laboratory Investigation, a journal that publishes original research on basic and clinical aspects of human disease and pathophysiology.

Statistics:

• Up to 90% of hepatocytes accumulated fat vacuoles in mice fed the CDE diet for 14 days.
• Decreased mitochondrial levels, together with an increase in superoxide radicals' levels, were observed in livers of CDE-fed mice.
• PGC1a protein levels decreased by 50% in CDE-treated mice, while PGC1a mRNA levels increased by 200% in comparison to control livers.
• ATP levels decreased by 25% in livers from CDE-fed mice after overnight fasting.

Sources:

• Laboratory Investigation (Fatty liver is associated with impaired activity of PPAR?-coactivator 1a (PGC1a) and mitochondrial biogenesis in mice Laboratory Investigation, 2011;91(7):1018-28)