The effects of a mitochondrial targeted peptide (elamipretide/SS31) on BAX recruitment and activation during apoptosis

Polydatin and Nicotinamide Rescue the Cellular Phenotype of Mitochondrial Diseases by Mitochondrial Unfolded Protein Response (mtUPR) Activation

Primary mitochondrial diseases result from mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA) genes, encoding proteins crucial for mitochondrial structure or function. Given that few disease-specific therapies are available for mitochondrial diseases, novel treatments to reverse mitochondrial dysfunction are necessary. In this work, we explored new therapeutic options in mitochondrial diseases using fibroblasts and induced neurons derived from patients with mutations in the GFM1 gene. This gene encodes the essential mitochondrial translation elongation factor G1 involved in mitochondrial protein synthesis. Due to the severe mitochondrial defect, mutant GFM1 fibroblasts cannot survive in galactose medium, making them an ideal screening model to test the effectiveness of pharmacological compounds. We found that the combination of polydatin and nicotinamide enabled the survival of mutant GFM1 fibroblasts in stress medium. We also demonstrated that polydatin and nicotinamide upregulated the mitochondrial Unfolded Protein Response (mtUPR), especially the SIRT3 pathway. Activation of mtUPR partially restored mitochondrial protein synthesis and expression, as well as improved cellular bioenergetics. Furthermore, we confirmed the positive effect of the treatment in GFM1 mutant induced neurons obtained by direct reprogramming from patient fibroblasts. Overall, we provide compelling evidence that mtUPR activation is a promising therapeutic strategy for GFM1 mutations.

Sodium New Houttuyfonate Induces Apoptosis of Breast Cancer Cells via ROS/PDK1/AKT/GSK3β Axis

BACKGROUND

Sodium new houttuyfonate (SNH) has been reported to have anti-inflammatory, anti-fungal, and anti-cancer effects. However, few studies have investigated the effect of SNH on breast cancer. The aim of this study was to investigate whether SNH has therapeutic potential for targeting breast cancer.

METHODS

Immunohistochemistry and Western blot analysis were used to examine the expression of proteins, flow cytometry was used to detect cell apoptosis and ROS levels, and transmission electron microscopy was used to observe mitochondria.

RESULTS

Differentially expressed genes (DEGs) between breast cancer-related gene expression profiles (GSE139038 and GSE109169) from GEO DataSets were mainly involved in the immune signaling pathway and the apoptotic signaling pathway. According to in vitro experiments, SNH significantly inhibited the proliferation, migration, and invasiveness of MCF-7 (human cells) and CMT-1211 (canine cells) and promoted apoptosis. To explore the reason for the above cellular changes, it was found that SNH induced the excessive production of ROS, resulting in mitochondrial impairment, and then promoted apoptosis by inhibiting the activation of the PDK1-AKT-GSK3β pathway. Tumor growth, as well as lung and liver metastases, were suppressed under SNH treatment in a mouse breast tumor model.

CONCLUSIONS

SNH significantly inhibited the proliferation and invasiveness of breast cancer cells and may have significant therapeutic potential in breast cancer.

Platelet Membrane-Encapsulated MSNs Loaded with SS31 Peptide Alleviate Myocardial Ischemia-Reperfusion Injury

Clinically, antioxidant therapy is a potential strategy for myocardial ischemia-reperfusion injury (MI/RI), a common complication of acute myocardial ischemia. The H-D-Arg-Dmt-Ly-Phe-NH2 (SS31) peptide is shown to have amazing antioxidant properties, but its utilization is limited by the peptide characteristics, such as the destruction by proteases and rapid metabolism. Silica nanoparticles (MSNs) comprise an excellent material for peptide delivery, owing to the protection effect relating to peptides. Moreover, platelet membrane (PLTM) is shown to be advantageous as a coat for nanosystems because of its specific protein composition, such that a PLTM-coated nanosystem has a stealth effect in vivo, able to target injury in the cardiovascular system. Based on this feature, we designed and prepared a novel nanocarrier to target SS31 delivery. This carrier is encapsulated by a platelet membrane and loaded with SS31 peptide into MSNs. The results reveal that this delivery system can target SS31 to the injured cardiovascular site, exert antioxidant function, and alleviate MI/RI.

The Influence of Mitochondrial Dynamics and Function on Retinal Ganglion Cell Susceptibility in Optic Nerve Disease

The important roles of mitochondrial function and dysfunction in the process of neurodegeneration are widely acknowledged. Retinal ganglion cells (RGCs) appear to be a highly vulnerable neuronal cell type in the central nervous system with respect to mitochondrial dysfunction but the actual reasons for this are still incompletely understood. These cells have a unique circumstance where unmyelinated axons must bend nearly 90° to exit the eye and then cross a translaminar pressure gradient before becoming myelinated in the optic nerve. This region, the optic nerve head, contains some of the highest density of mitochondria present in these cells. Glaucoma represents a perfect storm of events occurring at this location, with a combination of changes in the translaminar pressure gradient and reassignment of the metabolic support functions of supporting glia, which appears to apply increased metabolic stress to the RGC axons leading to a failure of axonal transport mechanisms. However, RGCs themselves are also extremely sensitive to genetic mutations, particularly in genes affecting mitochondrial dynamics and mitochondrial clearance. These mutations, which systemically affect the mitochondria in every cell, often lead to an optic neuropathy as the sole pathologic defect in affected patients. This review summarizes knowledge of mitochondrial structure and function, the known energy demands of neurons in general, and places these in the context of normal and pathological characteristics of mitochondria attributed to RGCs.