Small-Molecule Inhibition of MuRF1 Prevents Early Disuse-Induced Diaphragmatic Dysfunction and Atrophy

Abstract

In clinical conditions such as diaphragm paralysis or mechanical ventilation, disuse-induced diaphragmatic dysfunction (DIDD) is a condition that poses a threat to life. MuRF1 is a key E3-ligase involved in regulating skeletal muscle mass, function, and metabolism, which contributes to the onset of DIDD. We investigated if the small-molecule mediated inhibition of MuRF1 activity (MyoMed-205) protects against early DIDD after 12 h of unilateral diaphragm denervation. Wistar rats were used in this study to determine the compound’s acute toxicity and optimal dosage. For potential DIDD treatment efficacy, diaphragm contractile function and fiber cross-sectional area (CSA) were evaluated. Western blotting investigated potential mechanisms underlying MyoMed-205’s effects in early DIDD. Our results indicate 50 mg/kg bw MyoMed-205 as a suitable dosage to prevent early diaphragmatic contractile dysfunction and atrophy following 12 h of denervation without detectable signs of acute toxicity. Mechanistically, treatment did not affect disuse-induced oxidative stress (4-HNE) increase, whereas phosphorylation of (ser632) HDAC4 was normalized. MyoMed-205 also mitigated FoxO1 activation, inhibited MuRF2, and increased phospho (ser473) Akt protein levels. These findings may suggest that MuRF1 activity significantly contributes to early DIDD pathophysiology. Novel strategies targeting MuRF1 (e.g., MyoMed-205) have potential therapeutic applications for treating early DIDD.

MuRF‐1 is Involved in Laryngeal Muscle Denervation Atrophy by Regulating G‐Actin Ubiquitination

“…MuRF-1 is constantly increasingly expressed in denervation and exhibits muscle functional changes by regulating muscle protein ubiquitination and degradation by the proteasome. 16,[18][19][20] In our previous research, MuRF-1 was significantly upregulated in denervated internal laryngeal muscles and may be involved in muscle atrophy through the NF-κB/MuRF-1 pathway. 2,3 Given that the degradation of myocyte cytoskeletal proteins is a main feature of skeletal muscle denervated atrophy, we wondered whether MuRF-1 was involved therein.…”

“…MuRF‐1 is constantly increasingly expressed in denervation and exhibits muscle functional changes by regulating muscle protein ubiquitination and degradation by the proteasome 16,18–20 . In our previous research, MuRF‐1 was significantly upregulated in denervated internal laryngeal muscles and may be involved in muscle atrophy through the NF‐κB/MuRF‐1 pathway 2,3 .…”

“…28 Then, MyoMed-205 showed prevention of early disuse-induced diaphragmatic dysfunction and atrophy 12 hours after unilateral diaphragmatic denervation. 20 Feeding B16F10 melanoma mice with MyoMed-205 reduced MuRF-1 expression in tumorstressed muscle, improved muscle performance in wire suspension tests, and attenuated muscle weight loss. 29 Furthermore, compound (EMBL Chemistry Core ID #704946) is directed to the myofibrillar protein recognition domain of MuRF-1, which attenuated muscle wasting and contractile dysfunction in cardiac cachexia.…”

“…Firstly, P013222 was identified as a direct MuRF‐1 inhibitor because P013222 inhibited ubiquitination of MyHC type II protein from rabbit skeletal muscle in vitro 28 . Then, MyoMed‐205 showed prevention of early disuse‐induced diaphragmatic dysfunction and atrophy 12 hours after unilateral diaphragmatic denervation 20 . Feeding B16F10 melanoma mice with MyoMed‐205 reduced MuRF‐1 expression in tumor‐stressed muscle, improved muscle performance in wire suspension tests, and attenuated muscle weight loss 29 .…”

Efeitos da inibição farmacológica de MuRF1 em associação a eletroestimulação neuromuscular na massa e força do músculo esquelético.

“…Nos últimos anos nosso grupo de pesquisa tem se dedicado a compreender os efeitos da utilização de uma pequena-molécula desenhada para atuar em um aspecto particular da atividade do atrogene MuRF1 (21,22). No caso, trata-se da inibição de sua dimerização, que é fundamental para sua ação em proteínas miofibrilares, como no caso da titina (23).…”