Ferulic acid attenuates high glucose-induced MAM alterations via PACS2/IP3R2/FUNDC1/VDAC1 pathway activating proapoptotic proteins and ameliorates cardiomyopathy in diabetic rats.

BACKGROUND: Diabetic cardiomyopathy (DCM) is one of the severe complications of diabetes with no known biomarkers for early detection. Mitochondria-associated endoplasmic reticulum membranes (MAM) are less studied subcellular targets but an emerging area for exploration in metabolic disorders including DCM. We herein studied the role of MAMs and downstream mitochondrial functions in DCM. We also explored the efficacy of ferulic acid (FeA) against DCM via modulation of MAM and its associated signaling pathway. METHODS: The H9c2 cardiomyoblast cells were incubated with high concentration (33 mM) of d-glucose for 48 h to create a high glucose ambience in vitro. The expression of various critical proteins of MAM, mitochondrial function, oxidative phosphorylation (OxPhos) and the genesis of apoptosis were examined. The rats fed with high fat/high fructose/streptozotocin (single dose, i.p.) were used as a diabetic model and analyzed the insulin resistance and markers of cardiac hypertrophy and apoptosis. RESULTS: High glucose conditions caused the upregulation of MAM formation via PACS2, IP3R2, FUNDC1, and VDAC1 and decreased mitochondrial biogenesis, fusion and OxPhos. The upregulation of mitochondria-driven SMAC-HTRA2-ARTS-XIAP apoptosis and other cell death pathways indicate their critical roles in the genesis of DCM at the molecular level. The diabetic rats also showed cardiomyopathy with increased heart mass index, TNNI3K, troponin, etc. FeA effectively prevented the high glucose-induced MAM alterations and associated cellular anomalies both in vitro and in vivo. CONCLUSION: High glucose-induced MAM distortion and subsequent mitochondrial dysfunctions act as the stem of cardiomyopathy. MAM could be explored as a potential target to treat diabetic cardiomyopathy. Also, the FeA could be an attractive nutraceutical agent for diabetic cardiomyopathy.

In vitro and in vivo studies reveal the beneficial effects of chlorogenic acid against ER stress mediated ER-phagy and associated apoptosis in the heart of diabetic rat.

Endoplasmic reticulum (ER) and associated signaling pathways are involved in diabetic cardiomyopathy (DCM) however, detailed studies are not available. The present study investigated the role of ER stress and related pathways such as ER-phagy, apoptosis and their underlying mechanisms using appropriate models. Beneficial effect of chlorogenic acid was also evaluated against ER stress mediated DCM. H9c2 cells with high glucose (33 mM, in vitro model of hyperglycemia) showed significant activation of ER stress response (GRP78, PERK, IRE1α, ATF6α) and altered its regulatory proteins (PDI, ERO1α). Also, it enhanced ER-phagy through upregulation of Sec62, RTN3 and downregulation of FAM134B. High glucose caused apoptosis via increased levels of CHOP, caspase 12 and calnexin. All these proteins (PERK, IRE1α, ATF6α, RTN3, Sec62 and FAM134B) have been found to have a significant role in the functioning of heart such as excitation contraction coupling and we expect these alterations to induce cardiomyopathy during diabetes. This was confirmed in in vivo study too. High fat, high fructose diet with mild streptozotocin induced diabetic rats showed an increased expression of BNP confirming cardiac injury. We also noticed severe ER stress in the heart of diabetic animals. All these have contributed significantly into alterations in histopathology and increase of weight of the hearts. These findings clearly show that ER stress plays a vital protagonist in the progression of DCM. We also found chlorogenic acid is effective against hyperglycemia induced pathological alteration both in vitro as well as in vivo.

Beneficial properties of selenium incorporated guar gum nanoparticles against ischemia/reperfusion in cardiomyoblasts (H9c2).

Nanotechnology for the treatment and diagnosis has been emerging recently as a potential area of research and development. In the present study, selenium incorporated guar gum nanoparticles have been prepared by nanoprecipitation and characterized by transmission electron microscopy and particle size analysis. The nanoparticles were screened for antioxidant potential (metal chelation, total reducing power and hydroxyl radical scavenging activity) and were evaluated against the cell line based cardiac ischemia/reperfusion model with special emphasis on oxidative stress and mitochondrial parameters. The cell based cardiac ischemia model was employed using H9c2 cell lines. Investigations revealed that there was a significant alteration (P ≤ 0.05) in the innate antioxidant status (glutathione↓, glutathione peroxidase↓, thioredoxin reductase↓, superoxide dismutase↓, catalase↓, lipid peroxidation↑, protein carbonyl↑, xanthine oxidase↑ and caspase 3 activity↑), mitochondrial functions (reactive oxygen species generation, membrane potential, and pore opening) and calcium homeostasis (calcium ATPase and intracellular calcium overload) during both ischemia and reperfusion. For comparative evaluation, selenium, guar gum and selenium incorporated guar gum nanoparticles were evaluated for their protective properties against ischemia/reperfusion. The study reveals that selenium incorporated guar gum nanoparticles were better at protecting the cells from ischemia/reperfusion compared to selenium and guar gum nanoparticles. The potent antioxidant capability shown by the sample in in vitro assays may be the biochemical basis of its better biological activity. Further, the nanodimensions of the particle may be the additional factor responsible for its better effect.