85 research outputs found
Mitochondrial DNA haplogroup-dependence of drugs and xenobiotics toxicity
No full textPharmacogenomics is the study of how genes affect a individual response to drugs to develop medications tailored to a person’s genetic makeup because the efficacy/safety profile have not be the same way for everyone.
Mitochondria are characterized by a unique milieu, with an alkaline and negatively charged interior (pH value 8) due to the proton pumping associated with OXPHOS and a series of specific channels and carrier proteins. As a consequence, mitochondria can easily accumulate lipophilic compounds of cationic character and weak acids in their anionic form, particularly amphiphilic xenobiotics including ethidium bromide, 1-methyl-4 phenylpyridinium (MPP+), paraquat (1,1’-dimethyl-4,4’-bipyridinium dichloride; PQ) and others that can penetrate the inner mitochondrial membrane (IMM) freely since in their undissociated forms. Indeed, it is well understood that many drugs and chemicals can cause mitochondrial dysfunction (mitotoxicity) by interacting with mitochondrial DNA (mtDNA), protein synthesis, respiratory chain, other metabolic processes, channels and transporters Moreover, due to its peculiar uniparental maternal inheritance and high mutation rate, mtDNA presents different clusters of population-specific-polymorphism (SNPs) that characterize different maternal lineages (mitochondrial haplogroups). It has been demonstrated that many non-synonymous SNPs, cause amino acid variations in the mitochondrial-encoded proteins, potentially modifying OXPHOS activity and ROS production. Some of these haplotypes may confer vulnerability to, or protection from, various common diseases. Well-documented examples are the role of mtDNA haplotype in Parkinson’s disease (PD) and Leber’s hereditary optic neuropathy (LHON). It has been proposed that European haplogroups J and K are protective for PD. On the other hand the haplogroups J and T may influence mitochondrial dysfunction, resulting in an increased risk of PD. In addition the 11778/ND4, 14484/ND6 and 3460/ND1 LHON mutations are associated respectively with mitochondrial subhaplogroup J2b, J1c and K, as these mtDNA backgrounds may increase penetrance of LHON mutations.
Several reports suggest that environmental factors such as pesticides (e.g. rotenone), herbicides (e.g. paraquat) and MPTP or 1-methyl 4-phenyl 1,2,3,6-tetrahydro-pyridine (contaminant in the illicit synthesis of opiates) increase the risk of PD due to a reduction in ATP synthesis and increase of reactive oxygen species (ROS). Furthermore, tobacco smoking has been proposed as an environmental trigger of visual loss in LHON, due to the presence of substances, contained in the tobacco that can directly act inhibiting CI.
Researchers have also associated non synonymous variants in mtDNA with the development of side effects of drugs. Effectively the analysis of mtDNA haplogroup in patients with cancer treated with chemioterapic agent cisplatin (cisPt) revealed an increased incidence of hearing loss in haplogroup J, due to inhibition of mtDNA replication. It has also been shown that patients treated with the antibiotic Linezolid may develop LHON-like optic neuropathy, myelosuppression and lactic acidosis. This is possibly due to the inhibition of mitochondrial protein synthesis, which is modulated by the SNPs at positions 2706 and 3010, in the 16S gene of mtDNA. This sequence region is predicted to be very close to the Peptidyl Transferase Center (PTC) that is the binding site of several antibiotics.
To demonstrate that mitochondrial genetic variability may influence individual susceptibility to drugs toxicity (Linezolid and CisPt) or to toxic environmental factors (rotenone, MPP+, paraquat and cigarette smoking) we assessed in vitro cell viability, mitochondrial functions including ATP synthesis, activity of OXPHOS complexes and ROS generation, and biogenesis (mtDNA copy number) in a collection of transmitochondrial cytoplasmic hybrids (cybrids) carrying divergent human mtDNA haplogroups (N1b, H, J, T, U, and K) or LHON mutations, that have been defined by sequencing of D-loop region and then of the entire mtDNA. Cybrids were constructed from fibroblasts obtained, after informed consent, from skin biopsies of unrelated healthy subjects and LHON patients.
The results of this study demonstrated that mitochondrial genetic variability may influence individual susceptibility to drugs or environmental factors toxicity, highlighting interesting associations between specific haplogroups, mitochondrial functional alterations, and toxic agent. More in details: 1) haplogroup K1 was found to play a protective role against rotenone toxicity, whereas haplogroup J1 seem to be more susceptible to the action of both rotenone and MPP+; 2) haplogroup T seems to be more susceptible to the action of paraquat; 3) haplogroups H12 and T1 in association with the LHON mutation 3460/ND1, and haplogroups J1c and J2A all increase the susceptibility to mitochondrial damage after smoke exposure. Moreover haplogroup H1, characterized by SNPs 2706A/3010A in 16SrRNA is the most sensitive to Linezolid toxicity and haplogroup J appears to act as risk factor in CisPt toxicity.
Even though future studies will be necessary to better understand the mechanism of action of some of these molecules, studying the association between mitochondrial haplogroup and toxicity of drugs and chemicals is extremely useful to prevent toxicity in predisposed subjects. This may avoid the occurrence of adverse reactions leading to the withdrawal of drugs from the market or Black Box warnings by FDA. For these reasons, pharmaceutical companies have introduced early in the drug-development process stringent in vitro studies to evaluate mitochondrial function (respiratory chain, ROS, membrane potential and mtDNA)
Anxiolytic Therapy: A Paradigm of Successful Mitochondrial Pharmacology
No full textThe complex biochemistry and dynamic structure of mitochondria have prevented them from being prominent pharmacological targets. New mechanistic understanding of cholesterol transport and associated neurosteroidogenesis is providing evidence on therapeutic outcomes in mental disorders that is achievable via mitochondrial pharmacology. This warrants general attention on mitochondrial pharmacology to inform therapies
Pyroptosis targeting via mitochondria: An educated guess to innovate COVID‐19 therapies
No full textPyroptosis is a specialized form of inflammatory cell death which aids the defensive response against invading pathogens. Its normally tight regulation is lost during infection by the severe acute respiratory coronavirus 2 (SARS-CoV-2), and thus, uncontrolled pyroptosis disrupts the immune system and the integrity of organs defining the critical conditions in patients with high viral load. Molecular pathways engaged downstream of the formation and stabilization of the inflammasome, which are necessary to execute the process, have been uncovered and drugs are available for their regulation. However, the pharmacology of the upstream events, which are critical to sense and interpret the initial damage by the pathogen, is far from being elucidated. This limits our capacity to identify early markers and targets to ameliorate SARS-CoV-2 linked pyroptosis. Here, we focus attention on the mitochondria and pathways leading to their dysfunction, in order to elucidate the early steps of inflammasome formation and devise tools to predict and counter pathological states induced by SARS-CoV-2
Distinct mechanisms of pathogenic DJ-1 mutations in mitochondrial quality control
No full textThe deglycase and chaperone protein DJ-1 is pivotal for cellular oxidative stress responses and mitochondrial quality control. Mutations in PARK7, encoding DJ-1, are associated with early-onset familial Parkinson’s disease and lead to pathological oxidative stress and/or disrupted protein degradation by the proteasome. The aim of this study was to gain insights into the pathogenic mechanisms of selected DJ-1 missense mutations, by characterizing protein–protein interactions, core parameters of mitochondrial function, quality control regulation via autophagy, and cellular death following dopamine accumulation. We report that the DJ-1M26I mutant influences DJ-1 interactions with SUMO-1, in turn enhancing removal of mitochondria and conferring increased cellular susceptibility to dopamine toxicity. By contrast, the DJ-1D149A mutant does not influence mitophagy, but instead impairs Ca2+ dynamics and free radical homeostasis by disrupting DJ-1 interactions with a mitochondrial accessory protein known as DJ-1-binding protein (DJBP/EFCAB6). Thus, individual DJ-1 mutations have different effects on mitochondrial function and quality control, implying mutation-specific pathomechanisms converging on impaired mitochondrial homeostasis
The role of mtDNA haplogroups on metabolic features in narcolepsy type 1
No full textIntroduction: Hypocretin is a neuropeptide regulating sleep-wake cycle, as well as feeding behavior. Interestingly, a subset of NT1 patients become overweight/obese, with a high prevalence of dysmetabolic phenotype. Thus, we undertook the first analysis of mitochondrial DNA (mtDNA) haplogroups in patients well characterized for their metabolic features.
Materials and methods: We included the DNA of 246 NT1 patients. For the haplogroups identification was sequenced the non-coding region of mtDNA, the control region, and the haplogroups markers on coding region investigated by RFLP.
Results: Data showed an association between metabolic syndrome and haplogroup K (64.3%, P=0.008, OR/95% CI=4.58/1.39-15.1), decreasing after correction for age (OR/95% CI=2.09/0.66-6.65), probably due to an age effect. Furthermore, the low HDL level showed a trend towards with haplogroups J (83,3%, P=0.099, OR/95% CI=6.06/1.24-29.7 after age adjustment 6.73/0.65-69.9). Finally, both haplogroups J and K were associated (61.5% and 61.5%, P=0.028) with the hypertriglyceridemia
Discussion: In conclusion, our study provides clues indicating that mtDNA haplogroups J and K might modulate metabolic features of NT1 patients. To finally linking mtDNA backgrounds with metabolic alterations, it would be necessary to validate the data in a larger cohort, and analyzing the complete mitochondrial genome
L’influenza degli aplogruppi del mtDNA sulle caratteristiche metaboliche nella narcolessia di tipo 1
No full textN/
Haplogroup J mitogenomes are the most sensitive to the pesticide rotenone: Relevance for human diseases
No full textThere is growing evidence that the sequence variation of mitochondrial DNA (mtDNA), which clusters in population- and/or geographic-specific haplogroups, may result in functional effects that, in turn, become relevant in disease predisposition or protection, interaction with environmental factors and ultimately in modulating longevity. To unravel functional differences between mtDNA haplogroups we here employed transmitochondrial cytoplasmic hybrid cells (cybrids) grown in galactose medium, a culture condition that forces oxidative phosphorylation, and in the presence of rotenone, the classic inhibitor of respiratory Complex I. Under this experimental paradigm we assessed functional parameters such as cell viability and respiration, ATP synthesis, reactive oxygen species production and mtDNA copy number. Our analyses show that haplogroup J1, which is common in western Eurasian populations, is the most sensitive to rotenone, whereas K1 mitogenomes orchestrate the best compensation, possibly because of the haplogroup-specific missense variants impinging on Complex I function. Remarkably, haplogroups J1 and K1 fit the genetic associations previously established with Leber's hereditary optic neuropathy (LHON) for J1, as a penetrance enhancer, and with Parkinson's disease (PD) for K1, as a protective background. Our findings provide functional evidences supporting previous well-established genetic associations of specific haplogroups with two neurodegenerative pathologies, LHON and PD. Our experimental paradigm is instrumental to highlighting the subtle functional differences characterizing mtDNA haplogroups, which will be increasingly needed to dissect the role of mtDNA genetic variation in health, disease and longevity
Cloud-Based Design Analysis and Optimization Framework
No full textIntegration of analysis into early design phases in support of improved building performance has become increasingly important. It is considered a required response to demands on contemporary building design to meet environmental concerns. The goal is to assist designers in their decision making throughout the design of a building but with growing focus on the earlier phases in design during which design changes consume less effort than similar changes would in later design phases or during construction and occupation.Multi-disciplinary optimization has the potential of providing design teams with information about the potential trade-offs between various goals, some of which may be in conflict with each other. A commonly used class of optimization algorithms is the class of genetic algorithms which mimic the evolutionary process. For effective parallelization of the cascading processes occurring in the application of genetic algorithms in multi-disciplinary optimization we propose a cloud implementation and describe its architecture designed to handle the cascading tasks as efficiently as possible
Reduction of the ATPase inhibitory factor 1 (IF1) leads to visual impairment in vertebrates
No full textIn vertebrates, mitochondria are tightly preserved energy producing organelles, which sustain nervous system development and function. The understanding of proteins that regulate their homoeostasis in complex animals is therefore critical and doing so via means of systemic analysis pivotal to inform pathophysiological conditions associated with mitochondrial deficiency. With the goal to decipher the role of the ATPase inhibitory factor 1 (IF1) in brain development, we employed the zebrafish as elected model reporting that the Atpif1a−/− zebrafish mutant, pinotage (pnttq209), which lacks one of the two IF1 paralogous, exhibits visual impairment alongside increased apoptotic bodies and neuroinflammation in both brain and retina. This associates with increased processing of the dynamin-like GTPase optic atrophy 1 (OPA1), whose ablation is a direct cause of inherited optic atrophy. Defects in vision associated with the processing of OPA1 are specular in Atpif1−/− mice thus confirming a regulatory axis, which interlinks IF1 and OPA1 in the definition of mitochondrial fitness and specialised brain functions. This study unveils a functional relay between IF1 and OPA1 in central nervous system besides representing an example of how the zebrafish model could be harnessed to infer the activity of mitochondrial proteins during development
NH-sulfoximine: A novel pharmacological inhibitor of the mitochondrial F 1 F o ‐ATPase, which suppresses viability of cancerous cells
No full textBACKGROUND AND PURPOSE: The mitochondrial F(1)F(o)‐ATPsynthase is pivotal for cellular homeostasis. When respiration is perturbed, its mode of action everts becoming an F(1)F(o)‐ATPase and therefore consuming rather producing ATP. Such a reversion is an obvious target for pharmacological intervention to counteract pathologies. Despite this, tools to selectively inhibit the phases of ATP hydrolysis without affecting the production of ATP remain scarce. Here, we report on a newly synthesised chemical, the NH‐sulfoximine (NHS), which achieves such a selectivity. EXPERIMENTAL APPROACH: The chemical structure of the F(1)F(o)‐ATPase inhibitor BTB‐06584 was used as a template to synthesise NHS. We assessed its pharmacology in human neuroblastoma SH‐SY5Y cells in which we profiled ATP levels, redox signalling, autophagy pathways and cellular viability. NHS was given alone or in combination with either the glucose analogue 2‐deoxyglucose (2‐DG) or the chemotherapeutic agent etoposide. KEY RESULTS: NHS selectively blocks the consumption of ATP by mitochondria leading a subtle cytotoxicity associated via the concomitant engagement of autophagy which impairs cell viability. NHS achieves such a function independently of the F(1)F(o)‐ATPase inhibitory factor 1 (IF1). CONCLUSION AND IMPLICATIONS: The novel sulfoximine analogue of BTB‐06584, NHS, acts as a selective pharmacological inhibitor of the mitochondrial F(1)F(o)‐ATPase. NHS, by blocking the hydrolysis of ATP perturbs the bioenergetic homoeostasis of cancer cells, leading to a non‐apoptotic type of cell death
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