Changes in mitochondrial ultrastructure in SH-SY5Y cells during apoptosis induced by hemin

Human Milk Oligosaccharide 2'-Fucosyllactose Induces Neuroprotection from Intracerebral Hemorrhage Stroke

Intracerebral hemorrhage (ICH) occurs when brain blood vessels rupture, causing inflammation and cell death. 2-Fucosyllactose (2FL), a human milk oligosaccharide, has potent antiapoptotic and anti-inflammatory effects. The purpose of this study was to examine the protective effect of 2FL in cellular and rodent models of ICH. Hemin was added to a primary rat cortical neuronal and BV2 microglia coculture to simulate ICH in vitro. IBA1 and MAP2 immunoreactivities were used to determine inflammation and neuronal survival. Hemin significantly increased IBA1, while it reduced MAP2 immunoreactivity. 2FL significantly antagonized both responses. The protective effect of 2FL was next examined in a rat ICH model. Intracerebral administration of type VII collagenase reduced open-field locomotor activity. Early post-treatment with 2FL significantly improved locomotor activity. Brain tissues were collected for immunohistochemistry and qRT-PCR analysis. 2FL reduced IBA1 and CD4 immunoreactivity in the lesioned striatum. 2FL downregulated the expression of ER stress markers (PERK and CHOP), while it upregulated M2 macrophage markers (CD206 and TGFβ) in the lesioned brain. Taken together, our data support that 2FL has a neuroprotective effect against ICH through the inhibition of neuroinflammation and ER stress. 2FL may have clinical implications for the treatment of ICH.

The Interaction of Hemin, a Porphyrin Derivative, with the Purified Rat Brain 2-Oxoglutarate Carrier

The mitochondrial 2-oxoglutarate carrier (OGC), isolated and purified from rat brain mitochondria, was reconstituted into proteoliposomes to study the interaction with hemin, a porphyrin derivative, which may result from the breakdown of heme-containing proteins and plays a key role in several metabolic pathways. By kinetic approaches, on the basis of the single binding centre gated pore mechanism, we analyzed the effect of hemin on the transport rate of OGC in uptake and efflux experiments in proteoliposomes reconstituted in the presence of the substrate 2-oxoglutarate. Overall, our experimental data fit the hypothesis that hemin operates a competitive inhibition in the 0.5-10 µM concentration range. As a consequence of the OGC inhibition, the malate/aspartate shuttle might be impaired, causing an alteration of mitochondrial function. Hence, considering that the metabolism of porphyrins implies both cytoplasmic and mitochondrial processes, OGC may participate in the regulation of porphyrin derivatives availability and the related metabolic pathways that depend on them (such as oxidative phosphorylation and apoptosis). For the sake of clarity, a simplified model based on induced-fit molecular docking supported the in vitro transport assays findings that hemin was as good as 2-oxoglutarate to bind the carrier by engaging specific ionic hydrogen bond interactions with a number of key residues known for participating in the similarly located mitochondrial carrier substrate binding site.

Docosahexaenoic Acid Alleviates Oxidative Stress-Based Apoptosis Via Improving Mitochondrial Dynamics in Early Brain Injury After Subarachnoid Hemorrhage

Mitochondrial dysfunction is considered a crucial therapeutic target for early brain injury following subarachnoid hemorrhage (SAH). Emerging evidence indicates that docosahexaenoic acid (DHA), an essential omega-3 fatty acid, protects mitochondria in various chronic diseases. This study aimed to investigate the neuroprotective effects of DHA on mitochondrial dynamic dysfunction after EBI using in vivo and in vitro approaches. For in vivo experiments, the rat endovascular perforation SAH model was performed, whereby DHA was administered intravenously 1 h after induction of SAH. Primary cultured neurons treated with oxyhemoglobin (OxyHb) for 24 h were used to mimic SAH in vitro. Our results demonstrated that DHA improved neurological deficits and reduced brain edema in rats with SAH, and attenuated OxyHb-induced neuronal death in primary cultured cells. DHA reduced the amount of reactive oxygen species-positive cells and improved cell viability when compared to the SAH + vehicle group in vitro. DHA attenuated malondialdehyde levels and superoxide dismutase stress, increased Bcl2 and Bcl-xl, and decreased Bax and cleaved caspase-3 in vivo. Additionally, DHA ameliorated mitochondrial dysfunction, upregulated the mitochondrial fusion-related protein Optic Atrophy 1, and downregulated the mitochondrial fission-related protein Dynamin-Related-Protein 1 (Drp1) and Serine 616 phosphorylated Drp1 after SAH both in vitro and in vivo. Taken together, our current study demonstrates that DHA might prevent oxidative stress-based apoptosis after SAH. The characterization of the underlying molecular mechanisms may further improve mitochondrial dynamics-related signaling pathways.

Functional interaction of endoplasmic reticulum stress and hepatitis B virus in the pathogenesis of liver diseases

Hepatitis B virus (HBV) is a non-cytopathic virus that causes acute and chronic inflammatory liver diseases, often leading to the pathogenesis of hepatocellular carcinoma (HCC). Although many studies for the roles of HBV on pathogenesis of the liver diseases, such as non-alcoholic fatty liver disease (NAFLD), hepatic inflammation, cirrhosis, and HCC, have been reported, the mechanisms are not fully understood. Endoplasmic reticulum (ER) and mitochondria have the protective mechanisms to restore their damaged function by intrinsic or extrinsic stresses, but their chronic dysfunctions are associated with the pathogenesis of the various diseases. Furthermore, HBV can affect intra- or extracellular homeostasis through induction of ER and mitochondrial dysfunctions, leading to liver injury. Therefore, the mechanism by which HBV induces ER or mitochondrial stresses may be a therapeutic target for treatment of liver diseases.