Distinct genomic copy number in mitochondria of different mammalian organs

Abstract

This study shows that mitochondria in liver, kidney, heart, and brain of the mouse have a distinct mitochondrial density. It also demonstrates that the mtDNA copy number per mitochondrion is organ-specific. A reliable method of determining mitochondrial density per organ is by stereological analysis of tissue sections while mtDNA quantitation is by the use of radiolabelled mtDNA probe. This is the first study in which a comprehensive examination of mitochondrial density and quantitation of mitochondrial genomes in mouse organs have been done. In summary the variability is not only in mitochondrial density but also in genomic copy number in mitochondria of various tissues.

Quantifying compartment‐associated variations of protein abundance in proteomics data

“…We therefore calculated protein fold change distributions for each cellular compartment and found statistically significant shifts between such distributions (Fig 1B–D). We found a distinct increase in mitochondrial proteins in liver cells that can be readily captured from the comparison of lung and liver tissue proteomes (Geiger et al , 2013; average change of +1 log 2 FC, Mann–Whitney test P  =   5.3 × 10 −32 ; Fig 1B and Dataset EV1), consistent with the knowledge that hepatocytes have an elevated number of mitochondria as compared to other cell types (Veltri & Espiritu, 1990). Similar differences can be also detected between more closely related cell types deriving from the same organ.…”

Scaling properties of cell and organelle size

“…Functional necessity varies between tissue types and influences mitochondria size and density, both of which tend to be greater in muscle cells relative to those of other organs. 102 A macroscopicmicroscopic functional connection is also found between human fitness level and mitochondrial abundance. 103 Size scaling analysis can also provide insight into how organelle morphology is dependent on the way in which is it constructed (and vice versa).…”

Convergence of multiple signaling pathways is required to coordinately up-regulate mtDNA and mitochondrial biogenesis during T cell activation

“…What remains unclear, however, is how specific signaling pathways coordinate the many individual aspects of the mitochondrial biogenesis response or whether there are different biogenesis scenarios that can be initiated to attain specific amounts and/or functional states of mitochondria to meet changing cellular needs. For example, the mitochondrial genome in mammals is usually present at 1000-10,000 copies per cell and is regulated in a tissue-specific manner, presumably representing one mechanism to tailor mitochondrial function to meet specialized cellular needs (Veltri et al, 1990;Moraes, 2001). While, in general, there is good correlation between the amount of mtDNA and the number of organelles in various cell types, whether mtDNA and overall mitochondrial biogenesis are under control of distinct signaling pathways and factors has not been addressed systematically.…”