Concurrent acetylation of FoxO1/3a and p53 due to sirtuins inhibition elicit Bim/PUMA mediated mitochondrial dysfunction and apoptosis in berberine-treated HepG2 cells

Journal Article · Fri Jan 15 04:00:00 EST 2016 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/J.TAAP.2015.12.006· OSTI ID:22687882

Shukla, Shatrunajay ^[1]; Sharma, Ankita ^[1]; Pandey, Vivek Kumar ^[1]; Raisuddin, Sheikh ^[2]; Kakkar, Poonam ^[1]

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1. Herbal Research Section, CSIR — Indian Institute of Toxicology Research, Post Box No. 80, Mahatma Gandhi Marg, Lucknow‐226001 (India)
2. Department of Medical Elementology and Toxicology, Jamia Hamdard (Hamdard University), Hamdard Nagar, New Delhi ‐110062 (India)

Post-translational modifications i.e. phosphorylation and acetylation are pivotal requirements for proper functioning of eukaryotic proteins. The current study aimed to decode the impact of acetylation/deacetylation of non-histone targets i.e. FoxO1/3a and p53 of sirtuins (NAD{sup +} dependent enzymes with lysine deacetylase activity) in berberine treated human hepatoma cells. Berberine (100 μM) inhibited sirtuins significantly (P < 0.05) at transcriptional level as well as at translational level. Combination of nicotinamide (sirtuin inhibitor) with berberine potentiated sirtuins inhibition and increased the expression of FoxO1/3a and phosphorylation of p53 tumor suppressor protein. As sirtuins deacetylate non-histone targets including FoxO1/3a and p53, berberine increased the acetylation load of FoxO1/3a and p53 proteins. Acetylated FoxO and p53 proteins transcriptionally activate BH3-only proteins Bim and PUMA (3.89 and 3.87 fold respectively, P<0.001), which are known as direct activator of pro-apoptotic Bcl-2 family protein Bax that culminated into mitochondria mediated activation of apoptotic cascade. Bim/PUMA knock-down showed no changes in sirtuins' expression while cytotoxicity induced by berberine and nicotinamide was curtailed up to 28.3% (P < 0.001) and it restored pro/anti apoptotic protein ratio in HepG2 cells. Sirtuins inhibition was accompanied by decline in NAD{sup +}/NADH ratio, ATP generation, enhanced ROS production and decreased mitochondrial membrane potential. TEM analysis confirmed mitochondrial deterioration and cell damage. SRT-1720 (1–10 μM), a SIRT-1 activator, when pre-treated with berberine (25 μM), reversed sirtuins expression comparable to control and significantly restored the cell viability (P < 0.05). Thus, our findings suggest that berberine mediated sirtuins inhibition resulting into FoxO1/3a and p53 acetylation followed by BH3-only protein Bim/PUMA activation may in part be responsible for mitochondria-mediated apoptosis. - Highlights: • Berberine inhibits sirtuins at transcriptional as well as at translational level. • Sirtuins inhibition leads to acetylation of non-histone proteins, FoxO1/3a and p53. • Acetylated FoxO and p53 transcriptionally upregulate BH3-only proteins Bim and PUMA respectively. • BH3-only proteins trigger mitochondrial dysfunction culminating into apoptosis. • SRT-1720 (SIRT-1 activator) partially restores Bax/Bcl-2 ratio and reduces berberine induced cytotoxicity in HepG2 cells.

• OSTI ID: 22687882
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Vol. 291; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
ACETYLATION
ADENINES
ADP
ALBUMINS
APOPTOSIS
CATTLE
DNA
EDTA
HEPATOMAS
HISTONES
KREBS CYCLE
LYSINE
MITOCHONDRIA
NAD
NICOTINAMIDE
RECEPTORS
RIBOSE
TRANSCRIPTION FACTORS
UBIQUINONE