Proteomics Unveils Fibroblast–Cardiomyocyte Lactate Shuttle and Hexokinase Paradox in Mouse Muscles

Quantitative
mapping, given in biochemically interpretable units
such as mol per mg of total protein, of tissue-specific proteomes
is prerequisite for the analysis of any process in cells. We applied
label- and standard-free proteomics to characterize three types of
striated muscles: white, red, and cardiac muscle. The analysis presented
here uncovers several unexpected and novel features of striated muscles.
In addition to differences in protein expression levels, the three
muscle types substantially differ in their patterns of basic metabolic
pathways and isoforms of regulatory proteins. Importantly, some of
the conclusions drawn on the basis of our results, such as the potential
existence of a “fibroblast–cardiomyocyte lactate shuttle”
and the “hexokinase paradox” point to the necessity
of reinterpretation of some basic aspects of striated muscle metabolism.
The data presented here constitute a powerful database and a resource
for future studies of muscle physiology and for the design of pharmaceutics
for the treatment of muscular disorders.