Regulation and Quantification of Cellular Mitochondrial Morphology and Content

Abstract

Running title: Regulation and quantification of mitochondrial morphology and content. Word count: 15,454 (total)Characters: 107,091 (including spaces); 92,067 (excluding spaces) Keywords: mitochondrial biogenesis, mitochondrial dynamics, mitochondrial degradation, living cells, TMRM, microscopy, segmentation, image analysis.Page 2 of 37 ABSTRACTMitochondria play a key role in signal transduction, redox homeostasis and cell survival, which extends far beyond their classical functioning in ATP production and energy metabolism. In living cells, mitochondrial content ("mitochondrial mass") depends on the cell-controlled balance between mitochondrial biogenesis and degradation. These processes are intricately linked to changes in net mitochondrial morphology and spatiotemporal positioning ("mitochondrial dynamics"), which are governed by mitochondrial fusion, fission and motility. It is becoming increasingly clear that mitochondrial mass and dynamics, as well as its ultrastructure and volume, are mechanistically linked to mitochondrial function and the cell. This means that proper quantification of mitochondrial morphology and content is of prime importance in understanding mitochondrial and cellular physiology in health and disease. This review first presents how cellular mitochondrial content is regulated at the level of mitochondrial biogenesis, degradation and dynamics. Next we discuss how mitochondrial dynamics and content can be analyzed with a special emphasis on quantitative live-cell microscopy strategies.

Increased hepatic mitochondrial FA oxidation reduces plasma and liver TG levels and is associated with regulation of UCPs and APOC-III in rats

“…Mitochondria are active in β-oxidation of FAs and, in situations with excess uptake of lipids by the liver, an adaptive increase in mitochondrial oxidative capacity is required. Under these conditions, mitochondrial dysfunction will compromise metabolic performance and may lead to elevated production of reactive oxygen species (17). Hence, mitochondrial adaptations are important to protect against harmful effects of oxidative stress, inflammation, and intrahepatic accumulation of lipids (16, 18).…”

Editorial (Thematic Issue: Mitochondrial Biogenesis: Pharmacological Approaches)

“…Several pharmacological strategies to trigger these signaling cascades, according to these authors, are the use of bezafibrate to activate the PPAR-PGC-1α axis, the activation of AMPK by resveratrol and the use of Sirt1 agonists such as quercetin or resveratrol. Other strategies currently used include the addition of antioxidant supplements to the diet (dietary supplementation with antioxidants) such as L-carnitine, coenzyme Q 10 , MitoQ 10 and other mitochondria-targeted antioxidants , N-acetylcysteine (NAC), vitamin C, vitamin E vitamin K1, vitamin B, sodium pyruvate or α-lipoic acid.…”

“…Karl J. Tronstad [10] describe the mechanism that maintains this equilibrium and the available techniques to quantify mitochondrial morphology and content. After reviewing the advantages and disadvantages of the most common techniques and strategies (measuring oxygen consumption, biochemical biomarkers or by electron microscopy), we can find in this work a deep analysis on fluorescence microscopy for the detection of mitochondrial content, its visualization, quantitation and interpretation of results both in 2D and in 3D imaging, along with available software and strategies developed by this group and others.…”

The metabolic rate of cultured muscle cells from hybrid Coturnix quail is intermediate to that of muscle cells from fast-growing and slow-growing Coturnix quail

“…Mitochondrial volume in a cell depends on a balance between mitochondrial biogenesis and mitochondrial fusion. Mitochondrial density is tightly controlled by the cell to provide adequate amounts of ATP necessary to maintain metabolic rates (Tronstad et al 2014). Mitochondrial biogenesis is generally thought to be a response to a demand for energy, and mitochondrial fusion is thought of as a quality control mechanism (Tronstad et al 2014).…”

“…Mitochondrial density is tightly controlled by the cell to provide adequate amounts of ATP necessary to maintain metabolic rates (Tronstad et al 2014). Mitochondrial biogenesis is generally thought to be a response to a demand for energy, and mitochondrial fusion is thought of as a quality control mechanism (Tronstad et al 2014). Although a number of factors can influence cellular metabolism, we have shown that mitochondrial volume was higher in myoblasts from the F line than the C line, correlating with the differences in myoblast metabolic rates (McBride et al 2006).…”