Biology subjects

Musa, I.

Publications and source records attributed to Musa, I..

2 recordsLinked to original sources

bioRxiv2025

MuRF1 partners with TRIM72 to impair insulin signalling in skeletal muscle cells

Muscle RING-finger protein 1 (MuRF1, gene name: TRIM63) is well known as a critical molecular regulator in skeletal muscle atrophy. Despite the identification of several substrates and interaction partners for MuRF1, the precise molecular mechanisms by which MuRF1 causes skeletal muscle atrophy remain unclear. To gain further insight into the underlying mechanism of skeletal muscle atrophy, we applied targeted biochemical approaches, and identified tripartite motif-containing protein 72 (TRIM72) as a novel MuRF1-interacting protein. Subsequent analysis using MuRF1 knockout and rescue experiments showed that TRIM72 protein abundance is dependent on the presence of MuRF1 protein. Furthermore, TRIM72 protein level was increased by dexamethasone treatment in C2C12 myotubes, alongside increased MuRF1 protein level. Dexamethasone decreases IRS1/Akt signalling, protein synthesis, and glucose uptake specifically in wild-type myotubes, but not in MuRF1 KO myotubes. Further analysis showed that overexpression of TRIM72 impairs IRS1/Akt signalling without the presence of MuRF1, indicating that MuRF1 induces a negative impact on insulin signalling through a plausible cooperation with TRIM72. Our findings provide novel non-degradative molecular roles of MuRF1 that link together skeletal muscle atrophy and impaired insulin responses. HighlightsO_LIIdentification of MuRF1 and TRIM72 interaction in skeletal muscle cells C_LIO_LITRIM72 protein expression is dependent on the presence of MuRF1 protein C_LIO_LIDeletion of MuRF1 confers a protective effect against dexamethasone-induced impairment of IRS1/Akt signaling C_LIO_LITRIM72 is sufficient to impair IRS1/Akt signaling C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=149 HEIGHT=200 SRC="FIGDIR/small/658491v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@347734org.highwire.dtl.DTLVardef@7dfa1aorg.highwire.dtl.DTLVardef@aef16dorg.highwire.dtl.DTLVardef@16c3bde_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2021

Ubiquitin E3 ligases Atrogin-1 and MuRF1 protein contents are differentially regulated in the rapamycin-sensitive mTOR-S6K1 signaling pathway in C2C12 myotubes

Muscle-specific ubiquitin E3 ligases, Atrogin-1 and MuRF1, are highly expressed in multiple conditions of skeletal muscle atrophy. The PI3K/Akt/FoxO signaling pathway is well known to regulate Atrogin-1 and MuRF1 gene expressions. Evidence supporting this is largely based on stimuli by insulin and IGF-1, that activate anabolic signaling, including Akt and Akt-dependent transcription factors. However, Akt activation also activates the mammalian target of rapamycin complex 1 (mTORC1) which induces skeletal muscle hypertrophy. However, whether mTORC1-dependent signaling has a role in regulating Atrogin-1 and/or MuRF1 gene and protein expression is currently unclear. In this study, we confirmed that activation of insulin-mediated Akt signaling suppresses both Atrogin-1 and MuRF1 protein content and that inhibition of Akt increases both Atrogin-1 and MuRF1 protein content in C2C12 myotubes. Interestingly, inhibition of mTORC1 using a specific mTORC1 inhibitor, rapamycin, increased Atrogin-1, but not MuRF1, protein content. Furthermore, activation of AMP-activated protein kinase (AMPK), a negative regulator of the mTORC1 signaling pathway, also showed distinct time-dependent changes between Atrogin-1 and MuRF1 protein content, suggesting differential regulatory mechanisms between Atrogin-1 and MuRF1 protein content. To further explore the downstream of mTORC1 signaling, we employed a specific S6K1 inhibitor, PF-4708671, and found that Atrogin-1 protein content was dose-dependently increased with PF-4708671 treatment, whereas MuRF1 protein content was not significantly altered. Overall, our results indicate that Atrogin-1 and MuRF1 protein contents are regulated by different mechanisms, the downstream of Akt, and that Atrogin-1 protein content can be regulated by rapamycin-sensitive mTOR-S6K1 dependent signaling pathway.

cell biology↗