Table 1 Molecular biomarkers associated with muscle atrophy

MuRF1 (Muscle RING Finger 1)

40 kDa¹¹⁰

An E3 ubiquitin ligase expressed in skeletal and cardiac muscle tissues in muscle remodelling. Upregulation participates in skeletal muscle atrophy; downregulation leads to cardiac hypertrophy.

Atrogin-1/MAFbx (Muscle Atrophy F-Box)

~42 kDa¹¹¹

Muscle-specific F-box protein, when induced in catabolic states it is linked to muscle atrophy. Expression is detectable before muscle loss. Promotes muscle protein degradation by the ubiquitin-proteasome pathway.

Myostatin

~43 kDa¹¹²

Acts as myokine, negatively regulating Akt pathway, promoting protein synthesis, increasing ubiquitin-proteasome system activity to induce atrophy.

FoxO1

~70 kDa¹¹³

FOXOs induce the ubiquitin ligase Atrogin-1 and cause skeletal muscle atrophy.

FoxO3

~71 kDa¹¹⁴

FoxO4

~65 kDa¹¹⁵

Insulin-like growth factor-1 (IGF-1)

~8 kDa¹¹⁶

Muscle atrophy via the combined effects of altered protein synthesis, UPS activity, autophagy and muscle regeneration.

C-reactive protein (CRP)

~120 kDa¹¹⁷

CRP influences muscle cell size linked suppression of Muscle protein synthesis pathway.

Interleukin-6 (IL-6)

~21 kDa¹¹⁸

IL-6/gp130/JAK2/STAT3-pathway mediates sepsis-induced muscle atrophy.