Congratulations to Romain Bernasconi, who defended his doctoral thesis, Unravelling the Mechanisms of Energetics-Induced Fast-to-Slow Phenotypic Shift in Creatine-Deficient Mice, at TalTech on 3 December 2025.
The creatine kinase system helps muscles maintain their energy supply during contraction. When this system is disrupted, muscles can become smaller and change from fast, high-force fibres to slower, more fatigue-resistant fibres. Romain's thesis investigated how this adaptation differs between fast and slow skeletal muscles in two mouse models of creatine deficiency.
The work showed that mice lacking arginine:glycine amidinotransferase (AGAT) had severe atrophy and a fast-to-slow shift in fast muscle, associated with high activity of the energy sensor AMP-activated protein kinase (AMPK). In contrast, mice lacking guanidinoacetate N-methyltransferase (GAMT) showed only subtle changes. The findings suggest that guanidinoacetate, which can partly substitute for creatine in GAMT-deficient mice, may prevent some energy-sensing responses and muscle adaptations.
Romain was supervised by Rikke Birkedal and co-supervised by Marko Vendelin.