Mitochondrial Proteins

The CO2 evolution of intact potato tubers (Solanum tuberosum, L., var. “Bintje”) was analyzed during a 10-day period of their warm (25 ± 2°C) or cold (5 ± 1°C) storage, to evaluate cold-stress effects on expression and activities of plant uncoupling mitochondrial protein (PUMP) and alternative oxidase (AOX). CO2 evolution rates were analyzed at 20°C, to reflect their possible capacities. The 20°C CO2 production declined from 13 to 8 mg kg−1 h−1 after 2 days of warm storage and then (after 3 to 7 days) decreased from 8 to 6.5 mg kg−1 h−1. In contrast, 20°C CO2 evolution did not change after the first day of cold storage, increased up to 14.5 mg kg−1 h−1 after 2 days, and decreased to about 12 mg kg−1 h−1 after 3 to 7 days of cold storage. Cold storage increased PUMP expression as detected by Western blots and led to elevated capacities of both PUMP (44%) and CN-resistant AOX (10 times), but not the cytochrome pathway. Since we found that cold storage led to about the same mitochondrial respiration of 40 nmol O2 min−1 mg−1 attributable to each of the respective proteins, we conclude that both AOX and PUMP equally contribute to adaptation of potato tubers to cold.

The increased longevity in modern societies raised the attention to biological interventions that could promote a healthy aging. Mitochondria are main organelles involved in the production of adenosine triphosphate (ATP), the energetic substrate for cellular biochemical reactions. The production of ATP occurs through the oxidative phosphorylation of intermediate substrates derived from the breakdown of lipids, sugars, and proteins. This process is coupled to production of oxygen reactive species (ROS) that in excess will have a deleterious role in cellular function. The damage promoted by ROS has been emphasized as one of the main processes involved in senescence. In the last decades, the discovery of specialized proteins in the mitochondrial inner membrane that promote the uncoupling of proton flux (named uncoupling proteins-UCPs) from the ATP synthase shed light on possible mechanisms implicated in the buffering of ROS and consequently in the process of aging. UCPs are responsible...

Mitochondria are double-membrane enclosed eukaryotic organelles with a central role in numerous cellular functions. The ultrastructure of mitochondria varies considerably between tissues, organisms, and the physiological state of cells. Alterations and remodeling of inner membrane structures are evident in numerous human disorders and during apoptosis. The inner membrane is composed of two subcompartments, the cristae membrane and the inner boundary membrane. Recent advances in electron tomography led to the current view that these membrane domains are connected by rather small tubular structures, termed crista junctions. They have been proposed to regulate the dynamic distribution of proteins and lipids as well as of soluble metabolites between individual mitochondrial subcompartments. One example is the release of cytochrome c upon induction of apoptosis. However, only little is known on the molecular mechanisms mediating the formation and maintenance of cristae and crista junctions. Here we review the current knowledge of the factors that determine cristae morphology and how the latter is linked to mitochondrial function. Further, we formulate several theoretical models which could account for the de novo formation of cristae as well as their propagation from existing cristae.

It is hoped that an understanding of the genetic basis of Parkinson's disease (PD) will lead to an appreciation of the molecular pathogenesis of disease, which in turn will highlight potential points of therapeutic intervention. It is also hoped that such an understanding will allow identification of individuals at risk for disease prior to the onset of motor symptoms. A large amount of work has already been performed in the identification of genetic risk factors for PD and some of this work, particularly those efforts that focus on genes implicated in monogenic forms of PD, have been successful, although hard won. A new era of gene discovery has begun, with the application of genome wide association studies; these promise to facilitate the identification of common genetic risk loci for complex genetic diseases. This is the first of several high throughput technologies that promise to shed light on the (likely) myriad genetic factors involved in this complex, late-onset neurodegenerative disorder.

GV1001 is a 16-amino-acid vaccine peptide derived from the human telomerase reverse transcriptase sequence. We investigated the effects of GV1001 against β-amyloid (Aβ) oligomer-induced neurotoxicity in rat neural stem cells (NSCs). Primary culture NSCs were treated with several concentrations of GV1001 and/or Aβ₂₅₋₃₅ oligomer for 48 hours. GV1001 protected NSCs against the Aβ₂₅₋₃₅ oligomer in a concentration-dependent manner. Aβ₂₅₋₃₅ concentration dependently decreased viability, proliferation, and mobilization of NSCs and GV1001 treatment restored the cells to wild-type levels. Aβ₂₅₋₃₅ increased free radical levels in rat NSCs while combined treatment with GV1001 significantly reduced these levels. In addition, GV1001 treatment of Aβ₂₅₋₃₅-injured NSCs increased the expression level of survival-related proteins, including mitochondria-associated survival proteins, and decreased the levels of death and inflammation-related proteins, including mitochondria-associated death proteins. ...

Various molecular and cellular pathways are active in eukaryotes to control the quality and integrity of mitochondria. These pathways are involved in keeping a 'healthy' population of this essential organelle during the lifetime of the organism. Quality control (QC) systems counteract processes that lead to organellar dysfunction manifesting as degenerative diseases and ageing. We discuss disease- and ageing-related pathways involved in mitochondrial QC: mtDNA repair and reorganization, regeneration of oxidized amino acids, refolding and degradation of severely damaged proteins, degradation of whole mitochondria by mitophagy and finally programmed cell death. The control of the integrity of mtDNA and regulation of its expression is essential to remodel single proteins as well as mitochondrial complexes that determine mitochondrial functions. The redundancy of components, such as proteases, and the hierarchies of the QC raise questions about crosstalk between systems and thei...