Current advances in gene therapy of mitochondrial diseases

Mitochondrial diseases (MD) are a heterogeneous group of multisystem disorders involving metabolic errors. MD are characterized by extremely heterogeneous symptoms, ranging from organ-specific to multisystem dysfunction with different clinical courses. Most primary MD are autosomal recessive but maternal inheritance (from mtDNA), autosomal dominant, and X-linked inheritance is also known. Mitochondria are unique energy-generating cellular organelles designed to survive and contain their own unique genetic coding material, a circular mtDNA fragment of approximately 16,000 base pairs. The mitochondrial genetic system incorporates closely interacting bi-genomic factors encoded by the nuclear and mitochondrial genomes. Understanding the dynamics of mitochondrial genetics supporting mitochondrial biogenesis is especially important for the development of strategies for the treatment of rare and difficult-to-diagnose diseases. Gene therapy is one of the methods for correcting mitochondrial disorders.

EPOR/CD131-mediated attenuation of rotenone-induced retinal degeneration is associated with upregulation of autophagy genes

Mitochondrial dysfunction is a key driver of neurodegeneration. This study aimed to evaluate the protective potential of EPOR/CD131 (heterodimeric erythropoietin receptor) stimulation in the neurodegeneration caused by rotenone-induced mitochondrial dysfunction. The effects of erythropoietin (EPO) and an EPO mimetic peptide pHBSP were assessed using in vivo and in vitro models. Single injections of 10 µg/kg EPO or 5 µg/kg pHBSP significantly alleviated the degeneration of ganglion cells of the retina in a rotenone-induced retinopathy in rats (p < 0.05). Consistently, in vitro exposure of rotenone-treated murine primary neuroglial cultures to 500 nM EPO or pHBSP significantly rescued the survival of the cells (p < 0.005). The observed enhancement of LC3A, ATG7, Beclin-1, Parkin and BNIP3 mRNA expression by EPOR/CD131 agonists implicates the autophagy and mitophagy activation as a plausible mitoprotective mechanism.

Cytokines in Abdominal Aortic Aneurysm: Master Regulators With Clinical Application

Abdominal aortic aneurysm (AAA) is a potentially life-threatening disorder with a mostly asymptomatic course where the abdominal aorta is weakened and bulged. Cytokines play especially important roles (both positive and negative) among the molecular actors of AAA development. All the inflammatory cascades, extracellular matrix degradation and vascular smooth muscle cell apoptosis are driven by cytokines. Previous studies emphasize an altered expression and a changed epigenetic regulation of key cytokines in AAA tissue samples. Such cytokines as IL-6, IL-10, IL-12, IL-17, IL-33, IL-1β, TGF-β, TNF-α, IFN-γ, and CXCL10 seem to be crucial in AAA pathogenesis. Some data obtained in animal studies show a protective function of IL-10, IL-33, and canonical TGF-β signaling, as well as a dual role of IL-4, IFN-γ and CXCL10, while TNF-α, IL-1β, IL-6, IL-12/IL-23, IL-17, CCR2, CXCR2, CXCR4 and the TGF-β noncanonical pathway are believed to aggravate the disease. Altogether data highlight significance of cytokines as informative markers and predictors of AAA. Pathologic serum/plasma concentrations of IL-1β, IL-2, IL-6, TNF-α, IL-10, IL-8, IL-17, IFN-γ, and PDGF have been already found in AAA patients. Some of the changes correlate with the size of aneurysms. Moreover, the risk of AAA is associated with polymorphic variants of genes encoding cytokines and their receptors: CCR2 (rs1799864), CCR5 (Delta-32), IL6 (rs1800796 and rs1800795), IL6R (rs12133641), IL10 (rs1800896), TGFB1 (rs1800469), TGFBR1 (rs1626340), TGFBR2 (rs1036095, rs4522809, rs1078985), and TNFA (rs1800629). Finally, 5 single-nucleotide polymorphisms in gene coding latent TGF-β-binding protein (LTBP4) and an allelic variant of TGFB3 are related to a significantly slower AAA annual growth rate.

Retinal abnormalities in transgenic mice overexpressing aberrant human FUS[1-359] gene

Retinal damage is an optional sign in a number of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). The aim of this work was to assess the structural and functional state of the retina in a murine model of ALS caused by overexpression of the aberrant FUS protein [1-359]. The retinal examination was carried out on 12 transgenic and 13 wild-type mice of 2.5–3 months of age. The study revealed not statistically significant higher level of ophthalmoscopic violations in FUS[1-359] mice. Moreover, gene expression assay confirmed an increased expression of the inflammatory genes Vegfa, Il1b, Il6, Icam1, Tnfa. However, despite the detected structural and functional abnormalities, western blot analysis and quantitative PCR did not detect the expression of the protein and mRNA products of the FUS transgene in the retina of FUS[1-359] mice.

Triple-Knockout, Synuclein-Free Mice Display Compromised Lipid Pattern

Recent studies have implicated synucleins in several reactions during the biosynthesis of lipids and fatty acids in addition to their recognised role in membrane lipid binding and synaptic functions. These are among aspects of decreased synuclein functions that are still poorly acknowledged especially in regard to pathogenesis in Parkinson’s disease. Here, we aimed to add to existing knowledge of synuclein deficiency (i.e., the lack of all three family members), with respect to changes in fatty acids and lipids in plasma, liver, and two brain regions in triple synuclein-knockout (TKO) mice. We describe changes of long-chain polyunsaturated fatty acids (LCPUFA) and palmitic acid in liver and plasma, reduced triacylglycerol (TAG) accumulation in liver and non-esterified fatty acids in plasma of synuclein free mice. In midbrain, we observed counterbalanced changes in the relative concentrations of phosphatidylcholine (PC) and cerebrosides (CER). We also recorded a notable reduction in ethanolamine plasmalogens in the midbrain of synuclein free mice, which is an important finding since the abnormal ether lipid metabolism usually associated with neurological disorders. In summary, our data demonstrates that synuclein deficiency results in alterations of the PUFA synthesis, storage lipid accumulation in the liver, and the reduction of plasmalogens and CER, those polar lipids which are principal compounds of lipid rafts in many tissues. An ablation of all three synuclein family members causes more profound changes in lipid metabolism than changes previously shown to be associated with γ-synuclein deficiency alone. Possible mechanisms by which synuclein deficiency may govern the reported modifications of lipid metabolism in TKO mice are proposed and discussed.

Increased Expression of the Multimerin-1 Gene in α-Synuclein Knokout Mice

Multimerin-1 (Mmrn-1) is a soluble protein, also known as elastin microfibril interfacer 4 (EMILIN-4), found in platelets and in the endothelium of blood vessels. Its function and role in pathology are still not fully understood. Genetic modifications in alpha-synuclein gene (Snca) locus that mapped 160 Kb apart from Mmrn-1 in mouse genome, could weigh with regulatory elements of Mmrn-1 gene. We have studied the Mmrn-1 expression in brain cortex of three mouse lines with Snca knock-out: B6(Cg)-Snca^tm1.2Vlb/J, B6;129-Snca^tm1Sud/J, and B6;129X1-Snca^tm1Rosl/J. The 35-fold increase for Mmrn-1 mRNA level have been found in B6;129X1-Snca^tm1Rosl/J mice that carry in their genome foreign sequences including bacterial gene neo and a strong promoter of a mouse phosphoglycerate kinase (Pgk1) oriented towards Mmrn-1 gene. This effect on regulatory elements of Mmrn-1 gene as a result of modifications in Snca locus should be taken into consideration when using B6;129X1-Snca^tm1Rosl/J line, that is widely applied for study of neurodegeneration mechanisms.

STUDY OF ANTIATHEROSCLEROTIC AND ENDOTHELIOPROTECTIVE ACTIVITY OF PEPTIDE AGONISTS OF EPOR/CD131 HETERORECEPTOR

Introduction. The drugs affecting a mitochondrial dysfunction, oxidative stresses, apoptosis and inflammation of the vascular wall, have a high potential for the prevention and treatment of atherosclerotic lesions. In this regard, the use of EPOR/CD131 heteroreceptor agonists which have a similar spectrum of pharmacological effects, is one of the promising strategies in the treatment of cardiovascular diseases.

Materials and Methods. The study was carried out on 68 C57Bl/6J male mice. Atherosclerosis was simulated in transgenic animals with an endotheliospecific knockdown of the Polg gene by simulating a balloon injury and keeping on a Western diet. Then, the studied drugs were injected once every 3 days at the dose of 20 μg/kg for 27 days. On the 28-th day, the animals were euthanized and the area of atherosclerotic plaques was assessed. The gene expression associated with the processes of inflammation, antioxidant protection, apoptosis, and angiogenesis was also determined in the aortic tissues. In addition, the endothelium protective effect of peptides on primary cultures of endothelial cells of wild and transgenic Polg-D257A mice was studied.

Results. No statistically significant effect of drugs on the area of lipid infiltration have been found. However, the studied peptides have significantly reduced the expression of proinflammatory genes (iNos, Icam1, Vcam1, Sele, Il6, Tnfa), the genes associated with angiogenesis (Vegfa, Kdr, and Hif1a), the expression of proapoptic factors; they decreased the Bax/Bcl-2 ratio by more than 1.5 times. In addition, when supplemented with H2 O2  in vitro, peptides dose-dependently increased endothelial cell survival.

Conclusion. The erythropoietin-based peptides can be used to improve the functional state of the vascular wall against the background of atherosclerotic lesions and have a depressing effect on pathobiological processes associated with a mitochondrial dysfunction. In addition, the studied peptides have a significant endothelial protective effect in the induction of oxidative stress in vitro.