Respiratory chain complexes in dynamic mitochondria display a patchy distribution in life cells

Background: Mitochondria, the main suppliers of cellular energy, are dynamic organelles that fuse and divide frequently. Constraining these processes impairs mitochondrial is closely linked to certain neurodegenerative diseases. It is proposed that functional mitochondrial dynamics allows the exchange of compounds thereby providing a rescue mechanism. Methodology/Principal Findings: The question discussed in this paper is whether fusion and fission of mitochondria in different cell lines result in re-localization of respiratory chain (RC) complexes and of the ATP synthase. This was addressed by fusing cells containing mitochondria with respiratory complexes labelled with different fluorescent proteins and resolving their time dependent re-localization in living cells. We found a complete reshuffling of RC complexes throughout the entire chondriome in single HeLa cells within 2–3 h by organelle fusion and fission. Polykaryons of fused cells completely re-mixed their RC complexes in 10–24 h in a progressive way. In contrast to the recently described homogeneous mixing of matrix-targeted proteins or outer membrane proteins, the distribution of RC complexes and ATP synthase in fused hybrid mitochondria, however, was not homogeneous but patterned. Thus, complete equilibration of respiratory chain complexes as integral inner mitochondrial membrane complexes is a slow process compared with matrix proteins probably limited by complete fusion. In co-expressing cells, complex II is more homogenously distributed than complex I and V, resp. Indeed, this result argues for higher mobility and less integration in supercomplexes. Conclusion/Significance: Our results clearly demonstrate that mitochondrial fusion and fission dynamics favours the re-mixing of all RC complexes within the chondriome. This permanent mixing avoids a static situation with a fixed composition of RC complexes per mitochondrion

Flow-Mediated Vasodilation Predicts Outcome in Patients With Chronic Heart Failure Comparison With B-Type Natriuretic Peptide

ObjectivesThe aim of this study was to assess the predictive potency of impaired endothelium-dependent flow-mediated vasodilation (FMD) in patients with chronic heart failure (CHF).BackgroundChronic heart failure is associated with reduced FMD; the prognostic impact of this observation is unknown.MethodsSeventy-five ambulatory CHF patients (United Network of Organ Sharing [UNOS] status 2) with a left ventricular ejection fraction (LVEF) ≤30%, despite optimized medical therapy (angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker, 100%; beta-blocker, 81%), were evaluated. Using high-resolution ultrasound, FMD of the brachial artery was assessed in addition to other neurohormonal, clinical, and hemodynamic variables. Age, gender, New York Heart Association (NYHA) functional class, LVEF, hemodynamic variables, B-type natriuretic peptide (BNP) levels, medical therapy, cardiovascular risk factors, and FMD were analyzed for prediction of the combined end point conversion to UNOS status 1 or death in a multivariate Cox model.ResultsUp to three years, 21 patients (28%) converted to UNOS status 1, and 6 patients (8%) died. Univariate risk factors for the combined end point were log BNP (p = 0.0032), FMD (p = 0.0033), NYHA functional class (p = 0.0132), beta-blocker therapy (p = 0.0367), and mean blood pressure (p = 0.0406). In the multivariate analysis, only FMD (p = 0.0007), log BNP (p = 0.0032), and mean blood pressure (p = 0.0475) were independently related to the combined end point. In the Kaplan-Meier plot, significantly more patients with FMD <6.8% (median) reached the combined end point, as compared with patients with FMD >6.8% (p = 0.004).ConclusionsIn CHF, impaired FMD is a strong, independent predictor of conversion to UNOS status 1 or death

Cellular Localization and Antigenic Characterization of Crimean-Congo Hemorrhagic Fever Virus Glycoproteins

Crimean-Congo hemorrhagic fever virus (CCHFV), a member of the genus Nairovirus of the family Bunyaviridae, causes severe disease with high rates of mortality in humans. The CCHFV M RNA segment encodes the virus glycoproteins G(N) and G(C). To understand the processing and intracellular localization of the CCHFV glycoproteins as well as their neutralization and protection determinants, we produced and characterized monoclonal antibodies (MAbs) specific for both G(N) and G(C). Using these MAbs, we found that G(N) predominantly colocalized with a Golgi marker when expressed alone or with G(C), while G(C) was transported to the Golgi apparatus only in the presence of G(N). Both proteins remained endo-β-N-acetylglucosaminidase H sensitive, indicating that the CCHFV glycoproteins are most likely targeted to the cis Golgi apparatus. Golgi targeting information partly resides within the G(N) ectodomain, because a soluble version of G(N) lacking its transmembrane and cytoplasmic domains also localized to the Golgi apparatus. Coexpression of soluble versions of G(N) and G(C) also resulted in localization of soluble G(C) to the Golgi apparatus, indicating that the ectodomains of these proteins are sufficient for the interactions needed for Golgi targeting. Finally, the mucin-like and P35 domains, located at the N terminus of the G(N) precursor protein and removed posttranslationally by endoproteolysis, were required for Golgi targeting of G(N) when it was expressed alone but were dispensable when G(C) was coexpressed. In neutralization assays on SW-13 cells, MAbs to G(C), but not to G(N), prevented CCHFV infection. However, only a subset of G(C) MAbs protected mice in passive-immunization experiments, while some nonneutralizing G(N) MAbs efficiently protected animals from a lethal CCHFV challenge. Thus, neutralization of CCHFV likely depends not only on the properties of the antibody, but on host cell factors as well. In addition, nonneutralizing antibody-dependent mechanisms, such as antibody-dependent cell-mediated cytotoxicity, may be involved in the in vivo protection seen with the MAbs to G(C)