Specific Reactive Oxygen Species Production Research Articles

Anatomically specific reactive oxygen species production participates in Marfan syndrome aneurysm formation.

Marfan syndrome (MFS) is a connective tissue disorder that results in aortic root aneurysm formation. Reactive oxygen species (ROS) seem to play a role in aortic wall remodelling in MFS, although the mechanism remains unknown. MFS Fbn1C1039G/+ mouse root/ascending (AS) and descending (DES) aortic samples were examined using DHE staining, lucigenin‐enhanced chemiluminescence (LGCL), Verhoeff's elastin‐Van Gieson staining (elastin breakdown) and in situ zymography for protease activity. Fbn1C1039G/+ AS‐ or DES‐derived smooth muscle cells (SMC) were treated with anti‐TGF‐β antibody, angiotensin II (AngII), anti‐TGF‐β antibody + AngII, or isotype control. ROS were detected during early aneurysm formation in the Fbn1C1039G/+ AS aorta, but absent in normal‐sized DES aorta. Fbn1C1039G/+ mice treated with the unspecific NADPH oxidase inhibitor, apocynin reduced AS aneurysm formation, with attenuated elastin fragmentation. In situ zymography revealed apocynin treatment decreased protease activity. In vitro SMC studies showed Fbn1C1039G/+‐derived AS SMC had increased NADPH activity compared to DES‐derived SMC. AS SMC NADPH activity increased with AngII treatment and appeared TGF‐β dependent. In conclusion, ROS play a role in MFS aneurysm development and correspond anatomically with aneurysmal aortic segments. ROS inhibition via apocynin treatment attenuates MFS aneurysm progression. AngII enhances ROS production in MFS AS SMCs and is likely TGF‐β dependent.

The inherent high vulnerability of dopaminergic neurons toward mitochondrial toxins may contribute to the etiology of Parkinson′s disease

Although the exact mechanism(s) of the degeneration of dopaminergic neurons in Parkinson's disease (PD) is not well understood, mitochondrial dysfunction is proposed to play a central role. This proposal is strongly strengthened by the findings that compromised mitochondrial functions and/or exposure to mitochondrial toxins such as rotenone, paraquat, or MPTP causes degeneration of the midbrain dopaminergic system and manifest symptoms similar to Parkinson's disease in primates and rodents (Goldman, 2014). In fact, the specific dopaminergic toxin MPTP is one of the most commonly used models in the mechanistic studies of environmental factors associated with the etiology of PD, particularly due to the availability of direct and unequivocal clinical and biochemical evidence from human and primate subjects. Several decades of intense studies in many laboratories have led to the proposition of a general mechanism for the specific dopaminergic toxicity of MPTP (Przedborski and Jackson-Lewis, 1998). The salient features of this mechanism are (a) lipophilic pro-toxin, MPTP, freely crosses the blood-brain barrier and enters the brain; (b) in glial cells monoamine oxidase-B converts it to the toxic metabolite MPP+; (c) the polar MPP+ is extruded into the extracellular space through organic cation transporter-3; (d) presynaptic dopamine transporter (DAT) takes it up specifically into dopaminergic neurons; (e) in dopaminergic neurons, MPP+ accumulates in the synaptic vesicles and/or mitochondria; (f) mitochondrial MPP+ inhibits the mitochondrial complex-I of the electron transport chain, leading to cellular ATP depletion and excessive reactive oxygen species (ROS) production causing apoptotic cell death (Lotharius and O’Malley, 2000; Storch et al., 2004). Although this mechanism is generally well accepted, numerous recent studies seriously challenge the central dogma of this proposal that the specific dopaminergic toxicity of MPP+ is primarily due to the specific uptake into dopaminergic neurons through presynaptic DAT.

Abstract 208: Defining the functions of mitochondrial Telomerase Reverse Transcriptase

Over the last few years it has become clear that mitochondria are not only the powerhouses of the cells, having their sole function in producing ATP. Proteome-analyses of mitochondria from different organisms and organs revealed that more than 1000 proteins are localized in and or on the mitochondria. This by far exceeds the number of proteins required for classical mitochondrial functions, e.g. the respiratory chain, the tricarboxylic acid cycle, fatty acid oxidation and apoptosis. This suggests that many of these proteins have other, as yet unknown functions. We identified Telomerase Reverse Transcriptase (TERT), an enzyme that, in the nucleus, protects telomeres, the ends of the chromosomes, against shortening, also in the mitochondria. However, up to now only (TERT) deficient cells and mice or TERT overexpressing cells were used to study nuclear and mitochondrial functions of TERT. In this context, we demonstrated that reduction of endogenous TERT leads to increased reactive oxygen species (ROS) production in the cytosol as well as in the mitochondria. To analyze now specifically the functions of mitochondrial TERT, we isolated TERT deficient fibroblasts and transduced them with lentiviruses containing mitochondrially targeted TERT. We first validated these newly generated cells for transgene insertion and expression. Next, we analyzed compartment specific ROS production and apoptosis in the cells. We observed a reduction specifically in the levels of mitochondrial, but not cytosolic ROS. Moreover, apoptosis induction was significantly reduced in these cells compared to TERT deficient cells as well as cells containing endogenous TERT. Thus, mitochondrial TERT specifically reduces mitochondrially produced ROS and protects cells against apoptosis. In comparison to nuclear TERT, which has the main function to prolong telomeres, mitochondrial TERT specifically protects mitochondria from damage. Currently, we are creating mice that carry mitochondrially targeted TERT on an otherwise TERT deficient background for in vivo experiments.

Seminal leukocyte concentration and related specific reactive oxygen species production in patients with male accessory gland infections.

The aim of this study was to determine whether differences occur in seminal concentrations of white blood corpuscles (sWBC) and whether WBC production of reactive oxygen species (ROS) is related to the infiltration of one or more male sexual glands. We studied 70 infertile patients affected by bacterial male accessory gland infections (MAGI) who were divided clinically and, by ultrasound (US), into four well-characterized, aged-matched groups. Three of the groups presented an abnormal US scan (MAGI US+ groups): group P with prostatitis alone (n = 15), group PV with prostato-vesiculitis (n = 19), and group PVE with prostato-vesiculo-epididymitis (n = 22). The fourth group presented with a normal US scan (MAGI US- group) and was diagnosed with presumptive MAGI according to laboratory criteria (n = 14). In addition, 20 fertile males acted as controls. All patients underwent seminal and microbiological analyses as well as US scans. In addition, the WBC concentrations of whole semen and the WBC-rich 45% Percoll fraction (Pf45) as well as WBC-specific ROS production in the same sperm fraction were analysed. Semen samples from the PVE patient group exhibited significantly (P < 0.01) lower values of sperm parameters than those obtained from P, PV, MAGI US- and the control groups. The sWBC and Pf45 WBC concentration as well as baseline and fMLP-stimulated ROS counts in each MAGI US+ group were significantly (P < 0.01) higher than those found in the MAGI US- group and controls.