The wasting-associated metabolite succinate disrupts myogenesis and impairs skeletal muscle regeneration

Abstract

Background: Loss of muscle mass and function are major clinical phenomena 1 affecting most advanced cancer patients. Recent work shows that defects in 2 muscle regeneration contribute to cancer-associated wasting. Among the factors 3 implicated in wasting-associated suppression of muscle regeneration are 4 cytokines that interfere with myogenic signal transduction pathways. Less 5 understood is how other cancer/wasting-associated cues, such as 6 oncometabolites, contribute to muscle dysfunction. This study investigates how 7 the oncometabolite succinate affects myogenesis and muscle regeneration. 8 Methods:We leveraged an established ectopic metabolite treatment strategy to 9 evaluate the ability of intracellular succinate elevation to 1) affect myoblast 10 homeostasis (growth/proliferation, apoptosis), 2) stimulate wasting-associated 11 catabolism, and 3) modulate in vitro myogenesis. In vivo succinate 12 supplementation experiments were utilized to corroborate and extend in vitro 13 observations. Metabolic studies were then performed to investigate the impact of 14 succinate elevation on mitochondria function. 15Results: We found that in vitro succinate elevation in myoblasts interferes with 16 protein homeostasis and myogenic differentiation. Mice orally administered 17 succinate displayed smaller muscle myofiber diameters and exhibited impaired 18 skeletal muscle regeneration when challenged with barium chloride-induced 19 muscle injury. Finally, we found that succinate elevation was associated with 20 functional mitochondria deficits. 21 Conclusions: Overall, this study broadens the repertoire of wasting-associated 22 factors that can directly modulate muscle progenitor cell function and strengthens 23 the hypothesis that metabolic derangements are major contributors to cancer-24 associated muscle wasting. 25 Keywords: Muscle wasting, skeletal muscle, succinate, myogenesis 26 27 Succinate is an oncometabolite best known for its role as a TCA cycle 57 intermediate and central player in mitochondria metabolism and ATP generation. 58 Recently, new roles for succinate have emerged and include immune cell 59 modulation13, HIF-1a stabilization in cancer14, epigenome remodeling via 60 inhibition of alpha-ketoglutarate dependent dioxygenases15, and post-61 translational protein modification (succinylation)16. This expanding repertoire of 62 cellular activities suggests a broader role for succinate in regulating cellular 63 processes such as differentiation, fate decisions, and survival. Interestingly, a 64 recent study reported serum succinate accumulation as a biomarker capable of 65 distinguishing non-wasting, tumor-bearing, and tumor-bearing with weight loss 66 patients17. In the present study, we sought to determine if succinate elevation 67 directly impacts muscle cell function, with a particular emphasis on myogenic 68 differentiation given prior studies linking succinate levels to cell fate 69 decisions18,19. 70Alterations in the balance between muscle breakdown and 71 repair/regeneration underlie cancer-asso...

Itaconate and Its Derivatives Repress Early Myogenesis In Vitro and In Vivo

“…Succinate abundance has been proposed as a causative agent of muscle wasting. Treatments to elevate intracellular succinate concentration has been observed to decrease total muscle protein expression by ~25%, inhibit in vitro C2C12 myoblast cell myogenesis, decrease myofiber diameter in murine models, inhibit myogenesis in vivo following barium chloride injury, reduce respiration capacity by ~35% in myoblasts, and also disrupt a number of other metabolic processes within muscle cells ( 27 ). SDH has also been shown to have significantly reduced activity in sarcopenic muscle ( 28 ).…”

Succinate Dehydrogenase (SDH)-subunit C regulates muscle oxygen consumption and fatigability in an animal model of pulmonary emphysema

“…Succinate has also been involved in post-translational protein modification (succinylation) 59 , and in cellular signaling via a specific receptor such as G protein-coupled receptor succinate receptor 1 (SUCNR1) 60 ; all of which could amplify metabolic dysfunction and other processes. Interestingly, a recent study indicates that exogenous succinate supplementation to cultured muscle cells and mice undermines muscle regeneration after injury 61 .…”

Itaconate and its derivatives repress C2C12 myogenesis

“…Succinate abundance has been proposed as a causative agent of muscle wasting. Treatments to elevate intracellular succinate concentration has been observed to decrease total muscle protein expression by ~25%, inhibit in vitro C2C12 myoblast cell myogenesis, decrease myofiber diameter in murine models, inhibit myogenesis in vivo following barium chloride injury, reduce respiration capacity by ~35% in myoblasts, and also disrupt a number of other metabolic processes within muscle cells (17). SDH has also been shown to have significantly reduced activity in sarcopenic muscle (18).…”