No description available.

No description available.

No description available.

No description available.

Mitochondria are found in all cells of the body except red blood cells. Mitochondria is the organelle that produces the most ATP in the body, which is the cells energy carrier. All processes in the body require energy in one way or another, hence the function of mitochondria is very important. In mitochondrial disease, there is an impairment in the function of the mitochondria, where the respiration usually is affected. Mitochondria play a big role in the regulation of glucose-stimulated insulin secretion of the pancreatic β-cells hence why diabetes often can be caused by mitochondrial dysfunction. Diabetes often requires treatment to achieve normal blood sugar levels. Metformin, rosiglitazone and troglitazone are three drugs for treatment of type 2 diabetes and have been proven to affect mitochondrial function or the body negatively, hence why it is important to be careful with which treatment that is used in case of mitochondrial diabetes. The purpose of this ex vivo model with human mitochondria were to investigate with high resolution respirometry whether the antidiabetic drugs could reduce the respiration in mitochondria and at what concentration it became significant. The results showed that metformin did not decrease the respiration at all with additions in the range of 10 µM to 100 µM, which rosiglitazone and troglitazone did. The therapeutic concentrations of the drugs are lower than the concentrations investigated in this study. However, since healthy cells are used in this study the effect that the drugs have on impaired mitochondria could be different. The conclusion of this study is that there was a significant decrease in the respiration for two of three drugs and should be carefully used. Further studies with impaired mitochondria should be performed to really see what affect these drugs have.

The brain is one of the most energetically demanding organs within the human body and is cognitively susceptible to energetic deficits such that the rise in obesity, insulin resistance, and Alzheimer’s disease in recent decades pose a substantial threat to cognitive longevity. The therapeutic efficacy of ketones are well-established in epilepsy and are currently being applied to other disease states. Alzheimer’s disease is characterized by impairments in brain glucose uptake and metabolism in regions relevant to learning, memory, and cognition that progress with the disease. While brain glucose uptake is impaired, ketone uptake is unaltered, potentially enabling ketones to fuel the glucose-deficient brain. Using RNA-seq data acquired from multiple publicly available AD databases, we assessed glycolytic and ketolytic gene expression in post-mortem AD and cognitively normal control brains. Gene expression was normalized to brain region – parietal lobe, cerebellum, temporal cortex, frontal lobe, inferior frontal gyrus, parahippocampal gyrus, superior temporal gyrus – and cell type – neurons, astrocytes, oligodendrocytes, and microglia. We report impairments in glycolytic gene expression in regions of the brain relevant to memory and cognition in neurons and oligodendrocytes, but not ketolytic gene expression in neurons. The data are consistent with previous work and support clinical ketone intervention. The cognitive effects of ketogenic diets remain controversial, especially in healthy adults. To elucidate the effects of a ketogenic diet in healthy mice, C57BL6 mice were placed on a ketone-supplemented ketogenic diet for eight weeks. Recognition memory was assessed in a novel object recognition test and hippocampal bioenergetics were measured using high-resolution respirometry, western blot, and biochemical assays. The diet significantly improved recognition memory and enhanced hippocampal mitochondrial efficiency, measured by ATP production per unit of oxygen consumed, suggesting cognitive validity of the diet in middle-age. Long-term potentiation (LTP), the activity-dependent strengthening of synapses, within the hippocampus, is one of the molecular mechanisms of learning and memory formation. LTP of hippocampal Schaffer-collaterals was quantified in young adult C57BL/6 mice with field electrophysiology following ex vivo brain slice incubation with a β-hydroxybutyrate-rich ACSF. Mice were then placed on the ketone-supplemented diet for four weeks. Behavioral spatial memory was measured in the Morris water maze and Schaffer-collateral LTP was assessed with field electrophysiology. No meaningful changes in LTP and behavioral memory were observed with ketone treatment, suggesting ketogenic interventions may be more applicable in aging and pathologies that display cognitive deficits, rather than in healthy young adults. Together, these studies support the exploration of ketogenic interventions as a potential restorative measure in Alzheimer’s disease and preventative measure in aging, which may be impactful facing the rise of obesity and insulin resistance.

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Ceramides are sphingolipids that serve as important second messengers in an increasing number of stress-induced pathways. Ceramide has long been known to affect the mitochondria, altering both morphology and physiology. Lipopolysaccharide (LPS) is a prevalent circulating inflammatory agent in obesity, potentially mediating some of the pathologies associated with weight gain. Given previous findings of TLR4-mediated ceramide accrual and ceramide-mediated mitochondrial disruption, we questioned whether ceramide is necessary for LPS-induced mitochondrial disruption. We found that LPS treatment increased gene transcript levels of ceramide synthesis enzymes and mitochondrial fission proteins and increased ceramide content in cultured myotubes and in mouse tissue. Mitochondrial respiration from permeabilized red gastrocnemius was reduced from animals receiving LPS injections when compared with those receiving vehicle (PBS). However, respiration from mice receiving both LPS and myriocin, a ceramide inhibitor, (0.3 mg/kg) was similar to PBS-injected animals. We treated murine myotubes with similar LPS conditions. These cells demonstrated increased ceramide synthesis and increased levels of mitochondrial fission with LPS treatment; these effects were mitigated with the addition of myriocin. However, in contrast to the whole gastrocnemius response in animals receiving LPS, respiration from myotubes was increased with LPS alone, and even higher with both myriocin alone and myriocin with LPS. We also sought to assess the impact of ceramide on skeletal muscle mitochondrial structure and function. A primary observation was the rapid and dramatic division of mitochondria in ceramide-treated cells. This effect is likely a result of increased Drp1 action, as ceramide increased Drp1 expression and Drp1 inhibition prevented ceramide-induced mitochondrial fission. Further, we found that ceramide treatment reduced mitochondrial O2 consumption (i.e., respiration) in cultured myotubes and permeabilized red gastrocnemius muscle fiber bundles. Ceramide treatment also increased H2O2 levels and reduced Akt/PKB phosphorylation in myotubes. However, inhibition of mitochondrial fission via Drp1 knockdown completely protected the myotubes and fiber bundles from ceramide-induced metabolic disruption, including maintained mitochondrial respiration, reduced H2O2 levels, and unaffected insulin signaling. These data suggest that the forced and sustained mitochondrial fission that results from ceramide accrual may alter metabolic function in skeletal muscle, which is a prominent site not only of energy demand (via the mitochondria), but also of ceramide accrual with weight gain.

The thermotolerance, an adaptive phenomenon that is accompanied by the phenotypic plasticity which is the adjustment of physiology, biochemistry and metabolism of every cellular function by the hidden mechanism. Mitochondrion, the powerhouse of the cell that determines the functional integrity of every cellular homeostasis and functional phycological processes should provide its association in regulating the thermotolerance as well. This study assessed the mitochondrial function in regulating and determining the limit of thermo tolerance in the Daphnia magna of different geographical regions of the world, mainly sub grouped as temperature tolerant clones (IL) and temperature sensitive clones (GB). The acclimation effects or the adjustment of the preexisting biological properties help the organism adjust its biological processes to the changing habitat to maintain the cellular functional integrity. The clonal divergence as well as the acclimation show a clear pattern in limiting the thermotolerance and the prediction is the temperature tolerant clones should show higher adjustment of the mitochondrial function than temperature sensitive ones. We hypothesize that the damage in the mitochondrial membrane integrity by different mito-toxins should decrease the heat tolerance by decreasing the membrane potential and fluidity. The integrated mitochondrial function was assessed in acclimated clones by using the molecular studies as well as observation of behavioral and phenotypic plasticity. Due to the specific effects of each mito-toxins (CCCP, NaN3 and DNP) on different complexes (I-IV and ATP synthase) in ETC, we determined the mitochondrial membrane integrity by the Rhodamine 123 alongside with the lactate assay for measuring the mitochondrial integrity. Among all these three mito-toxins, CCCP show significant effect on limiting the heat tolerance. The lower lactate accumulation was observed in the temperature-tolerant clones acclimated in cold temperatures (18°C) which indicates the higher mitochondrial adjustment than the temperature sensitive clones. The concluding remark is that thermal tolerance is determined by the adjustment of mitochondrial function which accompanied with the adjustment to the mitochondrial respiration as well as the adjustment to membrane potential and fluidity.

Neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease are linked to mitochondrial dysfunction and the underexpression of TOM40, a protein with chaperone-like qualities that is responsible for transporting precursor proteins into the mitochondria. Overexpression of TOM40 is reported to partially restore mitochondrial dysfunction and decrease the accumulation of neurotoxic aggregates of α-synuclein. Our goal is to develop an effective method for delivery of TOM40 protein to the brain. Previous studies have used lentiviruses to carry TOM40 into the hippocampus of α-synuclein transgenic mice. The disadvantage of lentiviral transfection is the random insertions of the target gene into the host genome, which could cause toxic effects. Synthetic phospholipid vesicles containing TOM40 were considered as an alternative delivery method, but these "liposomes" elicit not only toxicity, but also an immune response. Thus, development of a safer delivery method of TOM40 protein is needed. We investigated exosomes, which are extracellular vesicles originating from multivesicular endosomes filled with protein, lipid, or RNA cargoes for cell-cell communication. Since exosomes are created from host cells, they are non-immunogenic and may be a more desirable method. Expression constructs have been made for the production of TOM40 protein within or on the surface of exosomes. In order to target the delivery of TOM40 to the brain, we attached peptides to the surface of the exosomes, which specifically interact with receptors on neural cells. We attempted to confirm the functionality of the expression constructs through immunocytochemistry followed by flow cytometry and Western blotting.