A mouse model for monitoring calpain activity under physiological and pathological conditions.
Calpains are Ca(2+)-dependent cysteine proteases known to be important for the regulation of cell functions and which aberrant activation causes cell death in a number of degenerative disorders. To provide a tool for monitoring the status of calpain activity in vivo under physiological and pathological conditions, we created a mouse model that expresses ubiquitously a fluorescent reporter consisting of eCFP and eYFP separated by a linker cleavable by the ubiquitous calpains. We named this mouse CAFI for calpain activity monitored by FRET imaging. Our validation studies demonstrated that the level of calpain activity correlates with a decrease in FRET (fluorescence resonance energy transfer) between the two fluorescent proteins. Using this model, we observed a small level of activity after denervation and fasting, a high level of activity during muscle regeneration and ischemia, and local activity in damaged myofibers after exercise. Finally, we crossed the CAFI mouse with the alpha-sarcoglycan-deficient model, demonstrating an increase of calpain activity at the steady state. Altogether, our results present evidence that CAFI mice could be a valuable tool in which to follow calpain activity at physiological levels and in disease states.
Bartoli
Marc
M
Généthon/CNRS-UMR8115, 1 rue de l'Internationale 91000 Evry, France.
Bourg
Nathalie
N
Stockholm
Daniel
D
Raynaud
Fabrice
F
Delevacque
Antony
A
Han
Yang
Y
Borel
Perrine
P
Seddik
Kenza
K
Armande
Nasser
N
Richard
Isabelle
I
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000737:chemistry* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D031541:Fluorescence Resonance Energy Transfer; D017930:Genes, Reporter; D006801:Humans; D008164:Luminescent Proteins / Q000737:chemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008956:Models, Chemical; D008957:Models, Genetic; D019636:Neurodegenerative Diseases / Q000378:metabolism
D001426:Bacterial Proteins; D008164:Luminescent Proteins; C054562:yellow fluorescent protein, Bacteria; D002154:Calpain; D002118:Calcium