Mechanisms of simvastatin myotoxicity: The role of autophagy flux inhibition

Emami, Arya; Shojaei, Shahla; Rosa, Simone C. da Silva; Aghaei, Mahmoud; Samiei, Ehsan; Vosoughi, Amir Reza; Kalantari, Forouh; Kawalec, Philip; Thliveris, James A.; Sharma, Pawan; Zeki, Amir A.; Akbari, Mohsen; Gordon, Joseph W.; Ghavami, Saeid

doi:10.1016/j.ejphar.2019.172616

Cited by 40 publications

(24 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…MitoSOX (Molecular Probes, M36008), MitoTracker Red CMXRos (Cell Signaling Technology, 9082), LysoTracker Red (Invitrogen, L7526), TMRM (Biotium, 70,017) and Hoechst 33,342 (Sigma, B2261) staining were described previously [30,31,59,[62][63][64]. Insulin-(Sigma, I0516) stimulated glucose uptake assay was measured as previously described using the fluorescent D-glucose analog 2NBDG (Invitrogen, N13195) [30].…”

Section: Fluorescent Stainingmentioning

confidence: 99%

See 1 more Smart Citation

BNIP3L/Nix-induced mitochondrial fission, mitophagy, and impaired myocyte glucose uptake are abrogated by PRKA/PKA phosphorylation

et al. 2020

Self Cite

View full text Add to dashboard Cite

Lipotoxicity is a form of cellular stress caused by the accumulation of lipids resulting in mitochondrial dysfunction and insulin resistance in muscle. Previously, we demonstrated that the mitophagy receptor BNIP3L/Nix is responsive to lipotoxicity and accumulates in response to a high-fat (HF) feeding. To provide a better understanding of this observation, we undertook gene expression array and shotgun metabolomics studies in soleus muscle from rodents on an HF diet. Interestingly, we observed a modest reduction in several autophagy-related genes. Moreover, we observed alterations in the fatty acyl composition of cardiolipins and phosphatidic acids. Given the reported roles of these phospholipids and BNIP3L in mitochondrial dynamics, we investigated aberrant mitochondrial turnover as a mechanism of impaired myocyte insulin signaling. In a series of gain-of-function and loss-of-function experiments in rodent and human myotubes, we demonstrate that BNIP3L accumulation triggers mitochondrial depolarization, calcium-dependent activation of DNM1L/DRP1, and mitophagy. In addition, BNIP3L can inhibit insulin signaling through activation of MTOR-RPS6KB/p70S6 kinase inhibition of IRS1, which is contingent on phosphatidic acids and RHEB. Finally, we demonstrate that BNIP3L-induced mitophagy and impaired glucose uptake can be reversed by direct phosphorylation of BNIP3L by PRKA/ PKA, leading to the translocation of BNIP3L from the mitochondria and sarcoplasmic reticulum to the cytosol. These findings provide insight into the role of BNIP3L, mitochondrial turnover, and impaired myocyte insulin signaling during an overfed state when overall autophagy-related gene expression is reduced. Furthermore, our data suggest a mechanism by which exercise or pharmacological activation of PRKA may overcome myocyte insulin resistance.

show abstract

Section: Fluorescent Stainingmentioning

confidence: 99%

“…TEM imaging was performed according to a protocol described previously [62][63][64]. Briefly, C2C12 cells myoblasts were seeded in 100-mm plates.…”

Section: Transmission Electron Microscopy (Tem)mentioning

confidence: 99%

BNIP3L/Nix-induced mitochondrial fission, mitophagy, and impaired myocyte glucose uptake are abrogated by PRKA/PKA phosphorylation

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Fluorescent staining: MitoSOX, MitoTracker Red CMXRos, and Hoechst 33342 staining was described previously 35,36,60,[63][64][65] . Glucose uptake assay was measured as previously described using the fluorescent D-glucose analog 2NBDG (200 μM; Molecular Probes) 35 .…”

Section: Methodsmentioning

confidence: 99%

“…Transmission electron microscopy (TEM): TEM imaging was performed according to a protocol described previously [63][64][65] . Briefly, C2C12 cells myoblasts were seeded in 100 mm plates.…”

Section: Methodsmentioning

confidence: 99%

Nix induced mitochondrial fission, mitophagy, and myocyte insulin resistance are abrogated by PKA phosphorylation

Rosa

Martens

Field

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

Lipotoxicity is a form of cellular stress caused by the accumulation of lipids resulting in mitochondrial dysfunction and insulin resistance in muscle. Previously, we demonstrated that the mitophagy receptor Nix is responsive to lipotoxicity and accumulates in response to diacylglycerols induced by high-fat (HF) feeding. In addition, previous studies have implicated autophagy and mitophagy in muscle insulin sensitivity. To provide a better understanding of these observations, we undertook gene expression array and shot-gun metabolomics studies in soleus muscle from rodents on an HF diet. Interestingly, we observed a modest reduction in several autophagy-related genes including Beclin-1, ATG3, and -5. Moreover, we observed alterations in the fatty acyl composition of cardiolipins and phosphatidic acids. Given the previously reported roles of these phospholipids and Nix in mitochondrial dynamics, we investigated aberrant mitochondrial fission and turn-over as a mechanism of myocyte insulin resistance. In a series of gain-of-function and loss-of-function experiments in rodent and human myotubes, we demonstrate that Nix accumulation triggers mitochondrial depolarization, fragmentation, calcium-dependent activation of DRP1, and mitophagy. In addition, Nix-induced mitochondrial fission leads to myotube insulin resistance through activation of mTOR-p70S6 kinase inhibition of IRS1, which is contingent on phosphatidic acids and Rheb1. Finally, we demonstrate that Nix-induced mitophagy and insulin resistance can be reversed by direct phosphorylation of Nix by PKA, leading to the translocation of Nix from the mitochondria and sarcoplasmic reticulum to the cytosol. These findings provide insight into the role of Nix-induced mitophagy and myocyte insulin resistance during an overfed state when overall autophagyrelated gene expression is reduced. Furthermore, our data suggests a mechanism by which exercise or pharmacological activation of PKA may overcome myocyte insulin resistance.

show abstract

“…The experiments involved exposing the cells to various doses of TMZ and Simva in GoC and in 2D culture systems. We paid special attention to three major mechanisms which are involved in the response of cancer cells to chemotherapy agents, including apoptosis, autophagy [10,43,44], and invasion. Initially, the cell viability and morphology of the cells that were treated with different concentrations of TMZ and Simva were studied and compared with the results of the conventional 2D culture systems.…”

Section: Chemotherapy Treatment: Analysis Of Programmed Cell Death Anmentioning

confidence: 99%

Investigating Programmed Cell Death and Tumor Invasion in a Three-Dimensional (3D) Microfluidic Model of Glioblastoma

Samiei

Seyfoori

Toyota

et al. 2020

IJMS

Self Cite

View full text Add to dashboard Cite

Glioblastoma multiforme (GBM) is a rapidly progressive and deadly form of brain tumor with a median survival rate of ~15 months. GBMs are hard to treat and significantly affect the patient’s physical and cognitive abilities and quality of life. Temozolomide (TMZ)—an alkylating agent that causes DNA damage—is the only chemotherapy choice for the treatment of GBM. However, TMZ also induces autophagy and causes tumor cell resistance and thus fails to improve the survival rate among patients. Here, we studied the drug-induced programmed cell death and invasion inhibition capacity of TMZ and a mevalonate cascade inhibitor, simvastatin (Simva), in a three-dimensional (3D) microfluidic model of GBM. We elucidate the role of autophagy in apoptotic cell death by comparing apoptosis in autophagy knockdown cells (Atg7 KD) against their scrambled counterparts. Our results show that the cells were significantly less sensitive to drugs in the 3D model as compared to monolayer culture systems. An immunofluorescence analysis confirmed that apoptosis is the mechanism of cell death in TMZ- and Simva-treated glioma cells. However, the induction of apoptosis in the 3D model is significantly lower than in monolayer cultures. We have also shown that autophagy inhibition (Atg7 KD) did not change TMZ and Simva-induced apoptosis in the 3D microfluidic model. Overall, for the first time in this study we have established the simultaneous detection of drug induced apoptosis and autophagy in a 3D microfluidic model of GBM. Our study presents a potential ex vivo platform for developing novel therapeutic strategies tailored toward disrupting key molecular pathways involved in programmed cell death and tumor invasion in glioblastoma.

show abstract

Mechanisms of simvastatin myotoxicity: The role of autophagy flux inhibition

Cited by 40 publications

References 68 publications

BNIP3L/Nix-induced mitochondrial fission, mitophagy, and impaired myocyte glucose uptake are abrogated by PRKA/PKA phosphorylation

BNIP3L/Nix-induced mitochondrial fission, mitophagy, and impaired myocyte glucose uptake are abrogated by PRKA/PKA phosphorylation

Nix induced mitochondrial fission, mitophagy, and myocyte insulin resistance are abrogated by PKA phosphorylation

Investigating Programmed Cell Death and Tumor Invasion in a Three-Dimensional (3D) Microfluidic Model of Glioblastoma

Contact Info

Product

Resources

About