Potential Treatment of Lysosomal Storage Disease through Modulation of the Mitochondrial-Lysosomal Axis

Compound probiotics regulate the NRF2 antioxidant pathway to inhibit aflatoxin B1-induced autophagy in mouse Sertoli TM4 cells

This study investigated the effects of compound probiotics (CP) on AFB1-induced cytotoxicity in Sertoli TM4 cells. The L9 (3 × 3) orthogonal test was conducted to determine the optimal CP required for high AFB1 degradation in the artificial gastrointestinal fluid in vitro. The maximal AFB1 degradation rate was 40.55 % (P < 0.05) when the final viable count was 1.0 × 105 CFU/mL for Bacillus subtilis, Lactobacillus casein, and Saccharomyces cerevisiae. The effects of CP and the CP supernatant (CPS) on TM4 cell viability were evaluated to achieve the optimal protective conditions. When CPS4 (corresponding to CP viable counts of 1.0 × 104 CFU/mL) was added to the TM4 cells for 24 h, the cell viability reached 108.86 % (P < 0.05). AFB1 reduced TM4 cell viability in a concentration- and time-dependent manner at an AFB1 concentration ranging from 0 to 1.5 μM after 48-h AFB1 exposure. The optimal AFB1 concentration/times for low- and high damage models were 0.5 and 1.25 μM both for 24 h, which decreased viability to 76.04 % and 65.35 %, respectively. however, CPS4 added to low- and high-damage models increased the cell viability to 97.43 % and 75.12 %, respectively (P < 0.05). Transcriptome sequencing was performed based on the following designed groups: the control, 0.5 μM AFB1, 1.25 μM AFB1, CPS4, and CPS4+0.5 μM AFB1. The Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis was further performed to identify significantly enriched signaling pathways, which were subsequently verified. It was shown that AFB1 induced apoptosis by blocking the PI3K-AKT-mTOR pathway and upregulating autophagy proteins such as LC3B, Beclin1, and ATG5 while inhibiting autophagic flux. CPS4 promoted AFB1 degradation, activated the p62-NRF2 antioxidant, and inhibited ROS/TRPML1 pathways, thereby reducing ROS production and inflammation and ultimately alleviating AFB1-induced autophagy and apoptosis. These findings supports the potential of probiotics to protect the male reproductive system from toxin damage.

Examining the Role of a Functional Deficiency of Iron in Lysosomal Storage Disorders with Translational Relevance to Alzheimer's Disease

The recently presented Azalea Hypothesis for Alzheimer's disease asserts that iron becomes sequestered, leading to a functional iron deficiency that contributes to neurodegeneration. Iron sequestration can occur by iron being bound to protein aggregates, such as amyloid β and tau, iron-rich structures not undergoing recycling (e.g., due to disrupted ferritinophagy and impaired mitophagy), and diminished delivery of iron from the lysosome to the cytosol. Reduced iron availability for biochemical reactions causes cells to respond to acquire additional iron, resulting in an elevation in the total iron level within affected brain regions. As the amount of unavailable iron increases, the level of available iron decreases until eventually it is unable to meet cellular demands, which leads to a functional iron deficiency. Normally, the lysosome plays an integral role in cellular iron homeostasis by facilitating both the delivery of iron to the cytosol (e.g., after endocytosis of the iron-transferrin-transferrin receptor complex) and the cellular recycling of iron. During a lysosomal storage disorder, an enzyme deficiency causes undigested substrates to accumulate, causing a sequelae of pathogenic events that may include cellular iron dyshomeostasis. Thus, a functional deficiency of iron may be a pathogenic mechanism occurring within several lysosomal storage diseases and Alzheimer's disease.

Revealing Mitochondrion-Lysosome Dynamic Interactions and pH Variations in Live Cells with a pH-Sensitive Fluorescent Probe

Mitochondrion-lysosome interactions have garnered significant attention in recent research. Numerous studies have shown that mitochondrion-lysosome interactions, including mitochondrion-lysosome contact (MLC) and mitophagy, are involved in various biological processes and pathological conditions. Single fluorescent probes are termed a pivotal chemical tool in unraveling the intricate spatiotemporal interorganelle interplay in live cells. However, current chemical tools are insufficient to deeply understand mitochondrion-lysosome dynamic interactions and related diseases, Moreover, the rational design of mitochondrion-lysosome dual-targeting fluorescent probes is intractable. Herein, we designed and synthesized a pH-sensitive fluorescent probe called INSA, which could simultaneously light up mitochondria (red emission) and lysosomes (green emission) for their internal pH differences. Employing INSA, we successfully recorded long-term dynamic interactions between lysosomes and mitochondria. More importantly, the increasing mitochondrion-lysosome interactions in ferroptotic cells were also revealed by INSA. Further, we observed pH variations in mitochondria and lysosomes during ferroptosis for the first time. In brief, this work not only introduced a pH-sensitive fluorescent probe INSA for the disclosure of the mitochondrion-lysosome dynamic interplays but also pioneered the visualization of the organellar pH alternation in a specific disease model.

Functional restoration of lysosomes and mitochondria through modulation of AKT activity ameliorates senescence

Senescence is a phenomenon defined by alterations in cellular organelles and is the primary cause of aging and aging-related diseases. Recent studies have shown that oncogene-induced senescence is driven by activation of serine/threonine protein kinases (AKT1, AKT2 and AKT3). In this study, we evaluated twelve AKT inhibitors and revealed GDC0068 as a potential agent to ameliorate senescence. Senescence-ameliorating effect was evident from the finding that GDC0068 yielded lysosomal functional recovery as observed by reduction in lysosomal mass and induction in autophagic flux. Furthermore, GDC0068-mediated restoration of lysosomal function activated the removal of dysfunctional mitochondria, resulting in restoration of mitochondrial function. Together, our findings revealed a unique mechanism by which senescence is recovered by functional restoration of lysosomes and mitochondria through modulation of AKT activity.

Delivery and assessment of a CRISPR/nCas9-based genome editing system on in vitro models of mucopolysaccharidoses IVA assisted by magnetite-based nanoparticles

Mucopolysaccharidosis IV A (MPS IVA) is a lysosomal disorder caused by mutations in the GALNS gene. Consequently, the glycosaminoglycans (GAGs) keratan sulfate and chondroitin 6-sulfate accumulate in the lysosomal lumen. Although enzyme replacement therapy has shown essential advantages for the patients, several challenges remain to overcome, such as the limited impact on the bone lesion and recovery of oxidative profile. Recently, we validated a CRISPR/nCas9-based gene therapy with promising results in an in vitro MPS IVA model. In this study, we have expanded the use of this CRISPR/nCas9 system to several MPS IVA fibroblasts carrying different GALNS mutations. Considering the latent need to develop more safety vectors for gene therapy, we co-delivered the CRISPR/nCas9 system with a novel non-viral vector based on magnetoliposomes (MLPs). We found that the CRISPR/nCas9 treatment led to an increase in enzyme activity between 5 and 88% of wild-type levels, as well as a reduction in GAGs accumulation, lysosomal mass, and mitochondrial-dependent oxidative stress, in a mutation-dependent manner. Noteworthy, MLPs allowed to obtain similar results to those observed with the conventional transfection agent lipofectamine. Overall, these results confirmed the potential of CRISPR/nCas9 as a genome editing tool for treating MPS IVA. We also demonstrated the potential use of MLPs as a novel delivery system for CRISPR/nCas9-based therapies.

Pathogenic mitochondrial dysfunction and metabolic abnormalities

Herein we trace links between biochemical pathways, pathogenesis, and metabolic diseases to set the stage for new therapeutic advances. Cellular and acellular microorganisms including bacteria and viruses are primary pathogenic drivers that cause disease. Missing from this statement are subcellular compartments, importantly mitochondria, which can be pathogenic by themselves, also serving as key metabolic disease intermediaries. The breakdown of food molecules provides chemical energy to power cellular processes, with mitochondria as powerhouses and ATP as the principal energy carrying molecule. Most animal cell ATP is produced by mitochondrial synthase; its central role in metabolism has been known for >80 years. Metabolic disorders involving many organ systems are prevalent in all age groups. Progressive pathogenic mitochondrial dysfunction is a hallmark of genetic mitochondrial diseases, the most common phenotypic expression of inherited metabolic disorders. Confluent genetic, metabolic, and mitochondrial axes surface in diabetes, heart failure, neurodegenerative disease, and even in the ongoing coronavirus pandemic.