Sodium butyrate attenuates rotenone-induced toxicity by activation of autophagy through epigenetically regulating PGC-1α expression in PC12 cells

Short-chain fatty acids (SCFAs) are considered the key molecular link between gut microbiota and pathogenesis of Parkinson's disease (PD). However, the role of SCFAs in PD pathogenesis is controversial. Autophagy is important for the degradation of α-synuclein, which is critical to the development of PD. However, whether SCFAs can regulate autophagy in PD remains unknown. We aimed to investigate the role of SCFAs and explore the potential mechanisms in rat dopaminergic PC12 cells treated with rotenone. Expression levels of α-synuclein, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and microtubule-associated protein 1 light chain 3 beta (LC3B)-II were detected by Western blot. Histone acetylation levels at PGC-1α promoter region were measured using chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR). Among the three SCFAs, sodium butyrate (NaB) protected against rotenone-induced toxicity. NaB activated autophagy pathway and reduced rotenone-induced α-synuclein expression through the activation of autophagy. Notably, NaB activated autophagy pathway through upregulating PGC-1α expression. More importantly, NaB promoted the levels of histone 3 lysine 9 acetylation (H3K9Ac) and histone 3 lysine 27 acetylation (H3K27Ac) at PGC-1α promoter region, indicating that NaB promotes PGC-1α expression via histone acetylation modification. In conclusion, NaB can protect against rotenone-induced toxicity through activation of the autophagy pathway by upregulating PGC-1α expression via epigenetic modification.

Mitochondrial Biogenesis, Activity, and DNA Isolation in Chondrocytes

Chondrocytes, the only cells in articular cartilage, are metabolically active and responsible for the turnover of extracellular matrix and maintenance of the tissue homeostasis. Changes in chondrocyte function can cause degradation of the matrix and loss of articular cartilage integrity, leading to development and progression of osteoarthritis (OA). These changes are exemplified by accumulated mitochondrial damage and dysfunction. Because mitochondria are the critical organelles to produce energy and play a key role in cellular processes, the approaches to assess mitochondrial function under both physiological and pathological conditions enable us to uncover the mechanisms on how dysfunction of mitochondria in chondrocytes mediates signaling pathways that are involved in disturbance of cartilage homeostasis. In this chapter, we describe the methods to evaluate mitochondrial biogenesis, activity and mitochondrial DNA (mtDNA) integrity in chondrocytes.

Ipragliflozin-induced improvement of liver steatosis in obese mice may involve sirtuin signaling

BACKGROUND

Sodium glucose cotransporter 2 (SGLT2) inhibitors are newly developed oral antidiabetic drugs. SGLT2 is primarily expressed in the kidneys and reabsorbs approximately 90% of the glucose filtered by the renal glomeruli. SGLT2 inhibitors lower glucose levels independently of insulin action by facilitating urinary glucose excretion. The SGLT2 inhibitor ipragliflozin has reportedly improved liver steatosis in animal models and clinical studies. However, the mechanisms by which SGLT2 inhibitors improve liver steatosis are not fully understood.

AIM

To investigate the ameliorative effects of ipragliflozin on liver steatosis and the mechanisms of these effects in obese mice.

METHODS

We analyzed 8-wk-old male obese (ob/ob) mice that were randomly divided into a group receiving a normal chow diet and a group receiving a normal chow diet supplemented with ipragliflozin (3 mg/kg or 10 mg/kg) for 4 wk. We also analyzed their lean sex-matched littermates receiving a normal chow diet as another control group. Body weight and liver weight were evaluated, and liver histology, immunoblotting, and reverse transcription-polymerase chain reaction analyses were performed.

RESULTS

Hepatic lipid accumulation was significantly ameliorated in ob/ob mice treated with 10 mg/kg ipragliflozin compared to untreated ob/ob mice irrespective of body weight changes. Ipragliflozin had no appreciable effects on hepatic oxidative stress-related gene expression levels or macrophage infiltration, but significantly reduced hepatic interleukin-1β (IL-1β) mRNA expression levels. Ipragliflozin increased both the mRNA and protein expression levels of sirtuin 1 (SIRT1) in the liver. The hepatic mRNA levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), peroxisome proliferator-activated receptor α (PPARα), and fibroblast growth factor-21 (FGF21) were also significantly higher in ipragliflozin-treated ob/ob mice than in untreated ob/ob mice.

CONCLUSION

Our study suggests that the liver steatosis-ameliorating effects of ipragliflozin in ob/ob mice may be mediated partly by hepatic SIRT1 signaling, possibly through the PGC-1α/PPARα-FGF21 pathway.

Natural products, PGC-1 , and Duchenne muscular dystrophy

Peroxisome proliferator-activated receptor γ (PPARγ) is a transcriptional coactivator that binds to a diverse range of transcription factors. PPARγ coactivator 1 (PGC-1) coactivators possess an extensive range of biological effects in different tissues, and play a key part in the regulation of the oxidative metabolism, consequently modulating the production of reactive oxygen species, autophagy, and mitochondrial biogenesis. Owing to these findings, a large body of studies, aiming to establish the role of PGC-1 in the neuromuscular system, has shown that PGC-1 could be a promising target for therapies targeting neuromuscular diseases. Among these, some evidence has shown that various signaling pathways linked to PGC-1α are deregulated in muscular dystrophy, leading to a reduced capacity for mitochondrial oxidative phosphorylation and increased reactive oxygen species (ROS) production. In the light of these results, any intervention aimed at activating PGC-1 could contribute towards ameliorating the progression of muscular dystrophies. PGC-1α is influenced by different patho-physiological/pharmacological stimuli. Natural products have been reported to display modulatory effects on PPARγ activation with fewer side effects in comparison to synthetic drugs. Taken together, this review summarizes the current knowledge on Duchenne muscular dystrophy, focusing on the potential effects of natural compounds, acting as regulators of PGC-1α.

Clinical significance of expression of peroxisome proliferator-activated receptor γ coactivator 1α in the inflamed mucosa of patients with inflammatory bowel disease

AIM: To investigate the expression of peroxisome proliferator-activated receptor γ coactivator (PGC) 1α in the inflamed mucosa of patients with inflammatory bowel disease (IBD).

METHODS: Inflamed colonic mucosal biopsies were collected from 15 patients with ulcerative colitis (UC), 17 patients with Crohn's disease (CD) and 14 healthy subjects. Expression of PGC-1α mRNA and protein in the intestinal mucosa was detected by real-time PCR and immunohistochemistry, respectively.

RESULTS: Immunohistochemical analysis revealed that PGC-1α was mainly expressed in intestinal epithelial cells in healthy mucosa and lowly expressed in lamina propria mononuclear cells. The positive rate of PGC-1α protein expression in the intestinal mucosa of UC patients was significantly lower than that in healthy controls (P < 0.05), but no significant difference was found between CD patients and healthy controls (P > 0.05). Compared to healthy controls, the levels of PGC-1α mRNA were significantly decreased in the inflamed mucosa of UC patients (0.48 ± 0.15 vs 1.59 ± 0.38, P < 0.05), but not in CD patients.

CONCLUSION: Aberrant expression of PGC-1α may play an important role in the pathogenesis of UC. The induction of biological effect of PGC-1α may have a therapeutic role in the treatment of UC.