Table I.

A list of prominent yet unsolved questions for future research on muscle atrophy in Drosophila and mammals.

OUTSTANDING QUESTIONS FOR FUTURE RESEARCH
IN DROSOPHILA WHICH ARE THE MECHANISMS OF DEVELOPMENTAL MUSCLE GROWTH, ATROPHY, AND SEGMENTAL APOPTOSIS IN DROSOPHILA? WHAT DETERMINES THE DISTINCT SENSITIVITY TO HISTOLYSIS OF DIFFERENT INSECT MUSCLES DURING PUPAL METAMORPHOSIS? ARE DROSOPHILA MUSCLE PRECURSOR CELLS SIMILARLY REGULATED AS MAMMALIAN SATELLITE CELLS? IS THERE TURNOVER OF THE CONTRCTILE APPARATUS IN NORMAL MUSCLES?
IN MAMMALS WHAT IS THE BASIS FOR THE DIFFERENTIAL RESPONSE OF DIFFERENT MAMMALIAN FIBER TYPES TO CATABOLIC STIMULI? HOW ARE COMPONENTS OF THE MYOFIBRIL ASSEMBLED AND DEGRADED BOTH NORMALLY AND AT INCREASED RATES DURING ATROPHY, WHILE PRESERVING CONTRACTILE FUNCTION? IN ATROPHYING MUSCLES, HOW ARE THE INCREASES IN PROTEOLYSIS BY THE UBIQUITIN PROTEASOME PATHWAY AND BY AUTOPHAGY AND THE DECREASES IN PROTEIN SYNTHESIS COORDINATED? DO SYNCYTIAL APOPTOSIS AND NECROPTOSIS CONTRIBUTE TO SARCOPENIA? WHAT IS THE PRECISE CONTRIBUTION, IF ANY, OF SATELLITE STEM CELLS TO MUSCLE ATROPHY AND HYPERTROPHY?
IN BOTH HOW DO VARIOUS SIGNALING PATHWAYS AND TRANSCRIPTION FACTORS (NFκB, Junβ, etc.) INTERACT WITH FoxOs TO CAUSE (OR COMBAT) MUSCLE ATROPHY IN MAMMALS AND DROSOPHILA?