1
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Liang Z, Ralph-Epps T, Schmidtke MW, Lazcano P, Denis SW, Balážová M, Teixeira da Rosa N, Chakkour M, Hazime S, Ren M, Schlame M, Houtkooper RH, Greenberg ML. Upregulation of the AMPK-FOXO1-PDK4 pathway is a primary mechanism of pyruvate dehydrogenase activity reduction in tafazzin-deficient cells. Sci Rep 2024; 14:11497. [PMID: 38769106 PMCID: PMC11106297 DOI: 10.1038/s41598-024-62262-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 05/15/2024] [Indexed: 05/22/2024] Open
Abstract
Barth syndrome (BTHS) is a rare disorder caused by mutations in the TAFAZZIN gene. Previous studies from both patients and model systems have established metabolic dysregulation as a core component of BTHS pathology. In particular, features such as lactic acidosis, pyruvate dehydrogenase (PDH) deficiency, and aberrant fatty acid and glucose oxidation have been identified. However, the lack of a mechanistic understanding of what causes these conditions in the context of BTHS remains a significant knowledge gap, and this has hindered the development of effective therapeutic strategies for treating the associated metabolic problems. In the current study, we utilized tafazzin-knockout C2C12 mouse myoblasts (TAZ-KO) and cardiac and skeletal muscle tissue from tafazzin-knockout mice to identify an upstream mechanism underlying impaired PDH activity in BTHS. This mechanism centers around robust upregulation of pyruvate dehydrogenase kinase 4 (PDK4), resulting from hyperactivation of AMP-activated protein kinase (AMPK) and subsequent transcriptional upregulation by forkhead box protein O1 (FOXO1). Upregulation of PDK4 in tafazzin-deficient cells causes direct phospho-inhibition of PDH activity accompanied by increased glucose uptake and elevated intracellular glucose concentration. Collectively, our findings provide a novel mechanistic framework whereby impaired tafazzin function ultimately results in robust PDK4 upregulation, leading to impaired PDH activity and likely linked to dysregulated metabolic substrate utilization. This mechanism may underlie previously reported findings of BTHS-associated metabolic dysregulation.
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Affiliation(s)
- Zhuqing Liang
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Tyler Ralph-Epps
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | | | - Pablo Lazcano
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Simone W Denis
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Gastroenterology Endocrinology and Metabolism Institute, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Institute, Amsterdam, The Netherlands
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, The Netherlands
| | - Mária Balážová
- Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 84005, Bratislava, Slovakia
| | | | - Mohamed Chakkour
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Sanaa Hazime
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Mindong Ren
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, Grossman School of Medicine, New York University, New York, NY, USA
| | - Michael Schlame
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, Grossman School of Medicine, New York University, New York, NY, USA
| | - Riekelt H Houtkooper
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Gastroenterology Endocrinology and Metabolism Institute, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Institute, Amsterdam, The Netherlands
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, The Netherlands
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA.
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2
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Cheng M, Nie Y, Song M, Chen F, Yu Y. Forkhead box O proteins: steering the course of stem cell fate. CELL REGENERATION (LONDON, ENGLAND) 2024; 13:7. [PMID: 38466341 DOI: 10.1186/s13619-024-00190-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 02/26/2024] [Indexed: 03/13/2024]
Abstract
Stem cells are pivotal players in the intricate dance of embryonic development, tissue maintenance, and regeneration. Their behavior is delicately balanced between maintaining their pluripotency and differentiating as needed. Disruptions in this balance can lead to a spectrum of diseases, underscoring the importance of unraveling the complex molecular mechanisms that govern stem cell fate. Forkhead box O (FOXO) proteins, a family of transcription factors, are at the heart of this intricate regulation, influencing a myriad of cellular processes such as survival, metabolism, and DNA repair. Their multifaceted role in steering the destiny of stem cells is evident, as they wield influence over self-renewal, quiescence, and lineage-specific differentiation in both embryonic and adult stem cells. This review delves into the structural and regulatory intricacies of FOXO transcription factors, shedding light on their pivotal roles in shaping the fate of stem cells. By providing insights into the specific functions of FOXO in determining stem cell fate, this review aims to pave the way for targeted interventions that could modulate stem cell behavior and potentially revolutionize the treatment and prevention of diseases.
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Affiliation(s)
- Mengdi Cheng
- Laboratory of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an, China
| | - Yujie Nie
- Laboratory of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an, China
| | - Min Song
- Laboratory of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an, China
| | - Fulin Chen
- Laboratory of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an, China
- Provincial Key Laboratory of Biotechnology of Shaanxi, Northwest University, Xi'an, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Medicine, Northwest University, Xi'an, China
| | - Yuan Yu
- Laboratory of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an, China.
- Provincial Key Laboratory of Biotechnology of Shaanxi, Northwest University, Xi'an, China.
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Medicine, Northwest University, Xi'an, China.
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3
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Jiang C, Zhang J, Song Y, Song X, Wu H, Jiao R, Li L, Zhang G, Wei D. FOXO1 regulates bovine skeletal muscle cells differentiation by targeting MYH3. Int J Biol Macromol 2024; 260:129643. [PMID: 38253149 DOI: 10.1016/j.ijbiomac.2024.129643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/03/2024] [Accepted: 01/18/2024] [Indexed: 01/24/2024]
Abstract
The growth and development of bovine skeletal muscle and beef yield is closely intertwined. Our previous research found that forkhead box O1 (FOXO1) plays an important role in the regulation of beef muscle formation, but its specific mechanism is still unknown. In this study, we aimed to clarify the regulatory mechanism of FOXO1 in proliferation and differentiation of bovine skeletal muscle cells (BSMCs). The results showed that interfering with FOXO1 can promote proliferation and the cell G1/S phase of BSMCs by up-regulating the expression of PCNA, CDK1, CDK2, CCNA2, CCNB1, CCND1 and CCNE2. Besides, interfering with FOXO1 inhibited the apoptosis of BSMCs by up-regulating the expression of anti-apoptosis gene BCL2, while simultaneously down-regulating the expression of the pro-apoptosis genes BAD and BAX. Inversely, interfering with FOXO1 can promote the differentiation of BSMCs by up-regulating the expression of myogenic differentiation marker genes MYOD, MYOG, MYF5, MYF6 and MYHC. Furthermore, RNA-seq combined with western bolt, immunofluorescence and chromatin immunoprecipitation analysis showed that FOXO1 could regulate BSMCs differentiation process by influencing PI3K-Akt, Relaxin and TGF-beta signaling pathways, and target MYH3 for transcriptional inhibition. In conclusion, this study provides a basis for studying the role and molecular mechanism of FOXO1 in BSMCs.
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Affiliation(s)
- Chao Jiang
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Jiupan Zhang
- Institute of Animal Science, Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan 750021, China
| | - Yaping Song
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Xiaoyu Song
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Hao Wu
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Ruopu Jiao
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Lanlan Li
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Guijie Zhang
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China
| | - Dawei Wei
- College of Animal Science and Technology, Ningxia University, Yinchuan 750021, China; Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia Hui Autonomous Region, Yinchuan 750021, China.
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Liang Z, Ralph-Epps T, Schmidtke MW, Lazcano P, Denis SW, Balážová M, Chakkour M, Hazime S, Ren M, Schlame M, Houtkooper RH, Greenberg ML. Upregulation of the AMPK-FOXO1-PDK4 pathway is a primary mechanism of pyruvate dehydrogenase activity reduction and leads to increased glucose uptake in tafazzin-deficient cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.03.578755. [PMID: 38352304 PMCID: PMC10862887 DOI: 10.1101/2024.02.03.578755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Barth syndrome (BTHS) is a rare disorder caused by mutations in the TAFAZZIN gene. Previous studies from both patients and model systems have established metabolic dysregulation as a core component of BTHS pathology. In particular, features such as lactic acidosis, pyruvate dehydrogenase (PDH) deficiency, and aberrant fatty acid and glucose oxidation have been identified. However, the lack of a mechanistic understanding of what causes these conditions in the context of BTHS remains a significant knowledge gap, and this has hindered the development of effective therapeutic strategies for treating the associated metabolic problems. In the current study, we utilized tafazzin-knockout C2C12 mouse myoblasts (TAZ-KO) and cardiac and skeletal muscle tissue from tafazzin-knockout mice to identify an upstream mechanism underlying impaired PDH activity in BTHS. This mechanism centers around robust upregulation of pyruvate dehydrogenase kinase 4 (PDK4), resulting from hyperactivation of AMP-activated protein kinase (AMPK) and subsequent transcriptional upregulation by forkhead box protein O1 (FOXO1). Upregulation of PDK4 in tafazzin-deficient cells causes direct phospho-inhibition of PDH activity accompanied by increased glucose uptake and elevated intracellular glucose concentration. Collectively, our findings provide a novel mechanistic framework whereby impaired tafazzin function ultimately results in robust PDK4 upregulation, leading to impaired PDH activity and likely linked to dysregulated metabolic substrate utilization. This mechanism may underlie previously reported findings of BTHS-associated metabolic dysregulation.
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5
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Liu ZJ, Zhu CF. Causal relationship between insulin resistance and sarcopenia. Diabetol Metab Syndr 2023; 15:46. [PMID: 36918975 PMCID: PMC10015682 DOI: 10.1186/s13098-023-01022-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 03/08/2023] [Indexed: 03/15/2023] Open
Abstract
Sarcopenia is a multifactorial disease characterized by reduced muscle mass and function, leading to disability, death, and other diseases. Recently, the prevalence of sarcopenia increased considerably, posing a serious threat to health worldwide. However, no clear international consensus has been reached regarding the etiology of sarcopenia. Several studies have shown that insulin resistance may be an important mechanism in the pathogenesis of induced muscle attenuation and that, conversely, sarcopenia can lead to insulin resistance. However, the causal relationship between the two is not clear. In this paper, the pathogenesis of sarcopenia is analyzed, the possible intrinsic causal relationship between sarcopenia and insulin resistance examined, and research progress expounded to provide a basis for the clinical diagnosis, treatment, and study of the mechanism of sarcopenia.
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Affiliation(s)
- Zi-jian Liu
- Shenzhen Clinical Medical College, Southern Medical University, Guangdong, 518101 China
| | - Cui-feng Zhu
- Shenzhen Hospital of Southern Medical University, Guangdong, 518101 China
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6
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miR-183/96/182 Cluster Regulates the Development of Bovine Myoblasts through Targeting FoxO1. Animals (Basel) 2022; 12:ani12202799. [PMID: 36290185 PMCID: PMC9597811 DOI: 10.3390/ani12202799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/16/2022] [Accepted: 10/08/2022] [Indexed: 11/29/2022] Open
Abstract
Simple Summary In this work, we identified that the miR-183/96/182 cluster was highly expressed in bovine embryonic muscle; meanwhile, it widely existed in other organizations. Functional assays indicated that the miR-183/96/182 cluster targets the FoxO1 gene to regulate the proliferation and differentiation of bovine myoblasts. Abstract Muscle development is an important factor affecting meat yield and quality and is coordinated by a variety of the myogenic genes and signaling pathways. Recent studies reported that miRNA, a class of highly conserved small noncoding RNA, is actively involved in regulating muscle development, but many miRNAs still need to be further explored. Here, we identified that the miR-183/96/182 cluster exhibited higher expression in bovine embryonic muscle; meanwhile, it widely existed in other organizations. Functionally, the results of the RT-qPCR, EdU, CCK8 and immunofluorescence assays demonstrated that the miR-183/96/182 cluster promoted proliferation and differentiation of bovine myoblast. Next, we found that the miR-183/96/182 cluster targeted FoxO1 and restrained its expression. Meanwhile, the expression of FoxO1 had a negative correlation with the expression of the miR-183/96/182 cluster during myoblast differentiation. In a word, our findings indicated that the miR-183/96/182 cluster serves as a positive regulator in the proliferation and differentiation of bovine myoblasts through suppressing the expression of FoxO1.
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7
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Skeletal Muscle Dysfunction in Experimental Pulmonary Hypertension. Int J Mol Sci 2022; 23:ijms231810912. [PMID: 36142826 PMCID: PMC9501428 DOI: 10.3390/ijms231810912] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/10/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a serious, progressive, and often fatal disease that is in urgent need of improved therapies that treat it. One of the remaining therapeutic challenges is the increasingly recognized skeletal muscle dysfunction that interferes with exercise tolerance. Here we report that in the adult rat Sugen/hypoxia (SU/Hx) model of severe pulmonary hypertension (PH), there is highly significant, almost 50%, decrease in exercise endurance, and this is associated with a 25% increase in the abundance of type II muscle fiber markers, thick sarcomeric aggregates and an increase in the levels of FoxO1 in the soleus (a predominantly type I fiber muscle), with additional alterations in the transcriptomic profiles of the diaphragm (a mixed fiber muscle) and the extensor digitorum longus (a predominantly Type II fiber muscle). In addition, soleus atrophy may contribute to impaired exercise endurance. Studies in L6 rat myoblasts have showed that myotube differentiation is associated with increased FoxO1 levels and type II fiber markers, while the inhibition of FoxO1 leads to increased type I fiber markers. We conclude that the formation of aggregates and a FoxO1-mediated shift in the skeletal muscle fiber-type specification may underlie skeletal muscle dysfunction in an experimental study of PH.
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8
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Yin Yang 1 is required for PHD finger protein 20-mediated myogenic differentiation in vitro and in vivo. Cell Death Differ 2020; 27:3321-3336. [PMID: 32555448 DOI: 10.1038/s41418-020-0580-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 06/09/2020] [Accepted: 06/10/2020] [Indexed: 11/08/2022] Open
Abstract
The development of skeletal muscle requires progression of a highly ordered cascade of events comprising myogenic lineage commitment, myoblast proliferation, and terminal differentiation. The process of myogenesis is controlled by several myogenic transcription factors that act as terminal effectors of signaling cascades and produce appropriate developmental stage-specific transcripts. PHD finger protein 20 (PHF20) is a multidomain protein and subunit of a lysine acetyltransferase complex that acetylates histone H4 and p53, but its function is unclear. Notably, it has been reported that PHF20 knockout mice die shortly after birth and display a wide variety of phenotypes within the skeletal and hematopoietic systems. Therefore, the putative role of PHF20 in myogenic differentiation was further investigated. In the present study, we found that protein and mRNA expression levels of PHF20 were decreased during myogenic differentiation in C2C12 cells. At the same time, Yin Yang 1 (YY1) was also decreased during myogenic differentiation. PHF20 overexpression increased YY1 expression during myogenic differentiation, together with a delay in MyoD expression. PHF20 expression enhanced the transcriptional activity of YY1 while shRNA-mediated depletion of PHF20 resulted in the reduction of YY1 promoter activity in C2C12 cells. In addition, PHF20 directly bounds to the YY1 promoter in C2C12 cells. In a similar manner, YY1 expression was elevated while myosin heavy chain expression was decreased in PHF20 transgenic (TG) mice. Histological analysis revealed abnormalities in the shape and length of muscles in PHF20-TG mice. Furthermore, PHF20-TG muscles slowly regenerated after cardiotoxin injection, indicating that PHF20 affected muscle differentiation and regeneration after injury in vivo. Taken together, these results suggested that PHF20 plays an important role in myogenic differentiation by regulating YY1.
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9
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Baek MO, Ahn CB, Cho HJ, Choi JY, Son KH, Yoon MS. Simulated microgravity inhibits C2C12 myogenesis via phospholipase D2-induced Akt/FOXO1 regulation. Sci Rep 2019; 9:14910. [PMID: 31624287 PMCID: PMC6797799 DOI: 10.1038/s41598-019-51410-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 09/30/2019] [Indexed: 12/19/2022] Open
Abstract
The skeletal muscle system has evolved to maintain body posture against a constant gravitational load. Mammalian target of rapamycin (mTOR) regulates the mechanically induced increase in the skeletal muscle mass. In the present study, we investigated mTOR pathway in C2C12 myoblasts in a model of mechanical unloading by creating a simulated microgravity (SM) using 3 D clinorotation. SM decreased the phosphorylation of Akt at Ser 473, which was mediated by mTOR complex 2 (mTORC2), in C2C12 myoblasts, leading to a decrease in the cell growth rate. Subsequently, SM inhibited C2C12 myogenesis in an Akt-dependent manner. In addition, SM increased the phospholipase D (PLD) activity by enhancing PLD2 expression, resulting in the dissociation of mSIN1 from the mTORC2, followed by decrease in the phosphorylation of Akt at Ser 473, and FOXO1 at Ser 256 in C2C12 myoblasts. Exposure to SM decreased the autophagic flux of C2C12 myoblasts by regulation of mRNA level of autophagic genes in a PLD2 and FOXO1-dependent manner, subsequently, resulting in a decrease in the C2C12 myogenesis. In conclusion, by analyzing the molecular signature of C2C12 myogenesis using SM, we suggest that the regulatory axis of the PLD2 induced Akt/FOXO1, is critical for C2C12 myogenesis.
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Affiliation(s)
- Mi-Ock Baek
- Department of Health Sciences and Technology, GAIHST, Gachon University, Incheon, 21999, Republic of Korea.,Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, 21999, Republic of Korea.,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, 21999, Republic of Korea
| | - Chi Bum Ahn
- Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, 21999, Republic of Korea
| | - Hye-Jeong Cho
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, 21999, Republic of Korea.,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, 21999, Republic of Korea
| | - Ji-Young Choi
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, 21999, Republic of Korea.,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, 21999, Republic of Korea
| | - Kuk Hui Son
- Department of Thoracic and Cardiovascular Surgery, Gachon University Gil Medical Center, College of Medicine, Gachon University, Incheon, 21565, Republic of Korea.
| | - Mee-Sup Yoon
- Department of Health Sciences and Technology, GAIHST, Gachon University, Incheon, 21999, Republic of Korea. .,Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, 21999, Republic of Korea. .,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, 21999, Republic of Korea.
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10
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Leucine promotes differentiation of porcine myoblasts through the protein kinase B (Akt)/Forkhead box O1 signalling pathway. Br J Nutr 2019; 119:727-733. [PMID: 29569540 DOI: 10.1017/s0007114518000181] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leucine, one of the branched-chain amino acids, is the only amino acid to regulate protein turnover in skeletal muscle. Leucine not only increases muscle protein synthesis, but also decreases muscle protein degradation. It is well documented that leucine plays a positive role in differentiation of murine muscle cells. However, the role of leucine on porcine myoblast differentiation and its mechanism remains unclear. In this study, porcine myoblasts were induced to differentiate with differentiation medium containing different concentrations of leucine, and wortmannin was used to interdict the activity of protein kinase B (Akt). We found that leucine increased the number of myosin heavy chain-positive cells and creatine kinase activity. Moreover, leucine increased the mRNA and protein levels of myogenin and myogenic determining factor (MyoD). In addition, leucine increased the levels of phosphorylated Akt/Akt and phosphorylated Forkhead box O1 (P-FoxO1)/FoxO1, as well as decreased the protein level of FoxO1. However, wortmannin, a specific repressor of PI3K/Akt signalling pathway, attenuated the positive role of leucine on porcine myoblast differentiation. Our results suggest that leucine promotes porcine myoblast differentiation through the Akt/FoxO1 signalling pathway.
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11
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O'Neill BT, Bhardwaj G, Penniman CM, Krumpoch MT, Suarez Beltran PA, Klaus K, Poro K, Li M, Pan H, Dreyfuss JM, Nair KS, Kahn CR. FoxO Transcription Factors Are Critical Regulators of Diabetes-Related Muscle Atrophy. Diabetes 2019; 68:556-570. [PMID: 30523026 PMCID: PMC6385751 DOI: 10.2337/db18-0416] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 10/21/2018] [Indexed: 12/25/2022]
Abstract
Insulin deficiency and uncontrolled diabetes lead to a catabolic state with decreased muscle strength, contributing to disease-related morbidity. FoxO transcription factors are suppressed by insulin and thus are key mediators of insulin action. To study their role in diabetic muscle wasting, we created mice with muscle-specific triple knockout of FoxO1/3/4 and induced diabetes in these M-FoxO-TKO mice with streptozotocin (STZ). Muscle mass and myofiber area were decreased 20-30% in STZ-Diabetes mice due to increased ubiquitin-proteasome degradation and autophagy alterations, characterized by increased LC3-containing vesicles, and elevated levels of phosphorylated ULK1 and LC3-II. Both the muscle loss and markers of increased degradation/autophagy were completely prevented in STZ FoxO-TKO mice. Transcriptomic analyses revealed FoxO-dependent increases in ubiquitin-mediated proteolysis pathways in STZ-Diabetes, including regulation of Fbxo32 (Atrogin1), Trim63 (MuRF1), Bnip3L, and Gabarapl. These same genes were increased 1.4- to 3.3-fold in muscle from humans with type 1 diabetes after short-term insulin deprivation. Thus, FoxO-regulated genes play a rate-limiting role in increased protein degradation and muscle atrophy in insulin-deficient diabetes.
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Affiliation(s)
- Brian T O'Neill
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Gourav Bhardwaj
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Christie M Penniman
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Megan T Krumpoch
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Pablo A Suarez Beltran
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Katherine Klaus
- Division of Endocrinology and Metabolism, Mayo Clinic College of Medicine, Rochester, MN
| | - Kennedy Poro
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Mengyao Li
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Hui Pan
- Bioinformatics Core, Joslin Diabetes Center, Harvard Medical School, Boston, MA
- Department of Biomedical Engineering, Boston University, Boston, MA
| | - Jonathan M Dreyfuss
- Bioinformatics Core, Joslin Diabetes Center, Harvard Medical School, Boston, MA
- Department of Biomedical Engineering, Boston University, Boston, MA
| | - K Sreekumaran Nair
- Division of Endocrinology and Metabolism, Mayo Clinic College of Medicine, Rochester, MN
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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Muthuramalingam K, Kim SY, Kim Y, Kim HS, Jeon YJ, Cho M. Bigbelly seahorse (Hippocampus abdominalis)-derived peptides enhance skeletal muscle differentiation and endurance performance via activated P38MAPK/AKT signalling pathway: An in vitro and in vivo analysis. J Funct Foods 2019. [DOI: 10.1016/j.jff.2018.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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13
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Zhu G, Liu X, Fang Y, Zhai B, Xu R, Han G, Chen G, Xiao H, Hou C, Shen B, Li Y, Iwakura Y, Wang L, Jiang Z, Ma N, Liu G, Wang R. Increased mTOR cancels out the effect of reduced Xbp-1 on antibody secretion in IL-1α-deficient B cells. Cell Immunol 2018; 328:9-17. [DOI: 10.1016/j.cellimm.2018.02.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 02/05/2018] [Accepted: 02/22/2018] [Indexed: 12/27/2022]
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14
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FoxO1: a novel insight into its molecular mechanisms in the regulation of skeletal muscle differentiation and fiber type specification. Oncotarget 2018; 8:10662-10674. [PMID: 27793012 PMCID: PMC5354690 DOI: 10.18632/oncotarget.12891] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 10/19/2016] [Indexed: 02/03/2023] Open
Abstract
FoxO1, a member of the forkhead transcription factor forkhead box protein O (FoxO) family, is predominantly expressed in most muscle types. FoxO1 is a key regulator of muscle growth, metabolism, cell proliferation and differentiation. In the past two decades, many researches have indicated that FoxO1 is a negative regulator of skeletal muscle differentiation while contrasting opinions consider that FoxO1 is crucial for myoblast fusion. FoxO1 is expressed much higher in fast twitch fiber enriched muscles than in slow muscles and is also closely related to muscle fiber type specification. In this review, we summarize the molecular mechanisms of FoxO1 in the regulation of skeletal muscle differentiation and fiber type specification.
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Zhang S, Chen X, Huang Z, Chen D, Yu B, He J, Zheng P, Yu J, Luo J, Luo Y, Chen H. Effects of MicroRNA-27a on Myogenin Expression and Akt/FoxO1 Signal Pathway during Porcine Myoblast Differentiation. Anim Biotechnol 2017; 29:183-189. [DOI: 10.1080/10495398.2017.1348357] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Shurun Zhang
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Xiaoling Chen
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Zhiqing Huang
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Daiwen Chen
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Bing Yu
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Jun He
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Ping Zheng
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Jie Yu
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Junqiu Luo
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Yuheng Luo
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China
| | - Hong Chen
- College of Food Science, Sichuan Agricultural University, Yaan, Sichuan, P. R. China
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Yamashita A, Hatazawa Y, Hirose Y, Ono Y, Kamei Y. FOXO1 delays skeletal muscle regeneration and suppresses myoblast proliferation. Biosci Biotechnol Biochem 2016; 80:1531-5. [DOI: 10.1080/09168451.2016.1164585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Abstract
Unloading stress, such as bed rest, inhibits the regenerative potential of skeletal muscles; however, the underlying mechanisms remain largely unknown. FOXO1 expression, which induces the upregulated expression of the cell cycle inhibitors p57 and Gadd45α, is known to be increased in the skeletal muscle under unloading conditions. However, there is no report addressing FOXO1-induced inhibition of myoblast proliferation. Therefore, we induced muscle injury by cardiotoxin in transgenic mice overexpressing FOXO1 in the skeletal muscle (FOXO1-Tg mice) and observed regeneration delay in skeletal muscle mass and cross-sectional area in FOXO1-Tg mice. Increased p57 and Gadd45α mRNA levels, and decreased proliferation capacity were observed in C2C12 myoblasts expressing a tamoxifen-inducible active form of FOXO1. These results suggest that decreased proliferation capacity of myoblasts by FOXO1 disrupts skeletal muscle regeneration under FOXO1-increased conditions, such as unloading.
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Affiliation(s)
- Atsushi Yamashita
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Yukino Hatazawa
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Yuma Hirose
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Yusuke Ono
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Yasutomi Kamei
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
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Zou C, Fu Y, Li C, Liu H, Li G, Li J, Zhang H, Wu Y, Li C. Genome-wide gene expression and DNA methylation differences in abnormally cloned and normally natural mating piglets. Anim Genet 2016; 47:436-50. [DOI: 10.1111/age.12436] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2016] [Indexed: 01/24/2023]
Affiliation(s)
- C. Zou
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - Y. Fu
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - C. Li
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - H. Liu
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - G. Li
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - J. Li
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - H. Zhang
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - Y. Wu
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
| | - C. Li
- Key Lab of Agriculture Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
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Pilcher CM, Jones CK, Schroyen M, Severin AJ, Patience JF, Tuggle CK, Koltes JE. Transcript profiles in longissimus dorsi muscle and subcutaneous adipose tissue: a comparison of pigs with different postweaning growth rates. J Anim Sci 2016; 93:2134-43. [PMID: 26020309 DOI: 10.2527/jas.2014-8593] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although most pigs recover rapidly from stresses associated with the transition of weaning, a portion of the population lags behind their contemporaries in growth performance. The underlying biological and molecular mechanisms involved in postweaning differences in growth performance are poorly understood. The objective of this experiment was to use transcriptional profiling of skeletal muscle and adipose tissue to develop a better understanding of the metabolic basis for poor weaned-pig transition. A total of 1,054 pigs was reared in commercial conditions and weighed at birth, weaning, and 3 wk postweaning. Transition ADG (tADG) was calculated as the ADG for the 3-wk period postweaning. Nine pigs from both the lowest 10th percentile (low tADG) and the 60th to 70th percentile (high tADG) were harvested at 3 wk postweaning. Differential expression analysis was conducted in longissimus dorsi muscle (LM) and subcutaneous adipose tissue using RNA-Seq methodology. In LM, 768 transcripts were differentially expressed (DE), 327 with higher expression in low tADG and 441 with higher expression in high tADG pigs (q < 0.10). Expression patterns measured in LM by RNA-Seq were verified in 30 of 32 transcripts using quantitative PCR. No DE transcripts were identified in adipose tissue. To identify biological functions potentially underlying the effects of tADG on skeletal muscle metabolism and physiology, functional annotation analysis of the DE transcripts was conducted using DAVID and Pathway Studio analytic tools. The group of DE genes with lower expression in LM of low tADG pigs was enriched in genes with functions related to muscle contraction, glucose metabolism, cytoskeleton organization, muscle development, and response to hormone stimulus (enrichment score > 1.3). The list of DE genes with higher expression in low tADG LM was enriched in genes with functions related to protein catabolism (enrichment score > 1.3). Analysis of known gene-gene interactions identified possible regulators of these differences in gene expression in LM of high and low tADG pigs; these include forkhead box O1 (FOXO1), growth hormone (GH1), and the glucocorticoid receptor (NR3C1). Differences in gene expression between poor transitioning pigs and their contemporaries indicate a shift to decreased protein synthesis, increased protein degradation, and reduced glucose metabolism in the LM of low tADG pigs.
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Couch ME, Dittus K, Toth MJ, Willis MS, Guttridge DC, George JR, Chang EY, Gourin CG, Der-Torossian H. Cancer cachexia update in head and neck cancer: Pathophysiology and treatment. Head Neck 2015; 37:1057-72. [PMID: 24634283 DOI: 10.1002/hed.23696] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2014] [Indexed: 01/10/2023] Open
Abstract
The pathophysiology of cancer cachexia remains complex. A comprehensive literature search was performed up to April 2013 using PubMed, the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, and the Google search engine. In this review, we focus on the different mediators of impaired anabolism and upregulated catabolism that alter the skeletal muscle homeostasis resulting in the wasting of cancer cachexia. We present recent evidence of targeted treatment modalities from clinical trials along with their potential mechanisms of action. We also report on the most current evidence from randomized clinical trials using multimodal treatments in patients with cancer cachexia, but also the evidence from head and neck cancer-specific trials. A more complete understanding of the pathophysiology of the syndrome may lead to more effective targeted therapies and improved outcomes for patients.
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Affiliation(s)
- Marion E Couch
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, Vermont Cancer Center, University of Vermont, College of Medicine, Burlington, Vermont
| | - Kim Dittus
- Division of Hematology-Oncology, Department of Medicine, Vermont Cancer Center, University of Vermont, College of Medicine, Burlington, Vermont
| | - Michael J Toth
- Department of Molecular Physiology and Biophysics, University of Vermont, College of Medicine, Burlington, Vermont
| | - Monte S Willis
- Department of Pathology and Laboratory Medicine, McAllister Heart Institute, University of North Carolina, Chapel Hill, North Carolina
| | - Denis C Guttridge
- Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, Ohio
| | - Jonathan R George
- Department of Otolaryngology - Head and Neck Surgery, University of California, San Francisco, California
| | - Eric Y Chang
- University of Vermont, College of Medicine, Burlington, Vermont
| | - Christine G Gourin
- Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins Hospital, Baltimore, Maryland
| | - Hirak Der-Torossian
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, Vermont Cancer Center, University of Vermont, College of Medicine, Burlington, Vermont
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Sanchez AMJ, Candau RB, Bernardi H. FoxO transcription factors: their roles in the maintenance of skeletal muscle homeostasis. Cell Mol Life Sci 2014; 71:1657-71. [PMID: 24232446 PMCID: PMC11113648 DOI: 10.1007/s00018-013-1513-z] [Citation(s) in RCA: 211] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/27/2013] [Accepted: 10/30/2013] [Indexed: 12/23/2022]
Abstract
Forkhead box class O family member proteins (FoxOs) are highly conserved transcription factors with important roles in cellular homeostasis. The four FoxO members in humans, FoxO1, FoxO3, FoxO4, and FoxO6, are all expressed in skeletal muscle, but the first three members are the most studied in muscle. In this review, we detail the multiple modes of FoxO regulation and discuss the central role of these proteins in the control of skeletal muscle plasticity. FoxO1 and FoxO3 are key factors of muscle energy homeostasis through the control of glycolytic and lipolytic flux, and mitochondrial metabolism. They are also key regulators of protein breakdown, as they modulate the activity of several actors in the ubiquitin–proteasome and autophagy–lysosomal proteolytic pathways, including mitochondrial autophagy, also called mitophagy. FoxO proteins have also been implicated in the regulation of the cell cycle, apoptosis, and muscle regeneration. Depending of their activation level, FoxO proteins can exhibit ambivalent functions. For example, a basal level of FoxO factors is necessary for cellular homeostasis and these proteins are required for adaptation to exercise. However, exacerbated activation may occur in the course of several diseases, resulting in metabolic disorders and atrophy. A better understanding of the precise functions of these transcriptions factors should thus lead to the development of new therapeutic approaches to prevent or limit the muscle wasting that prevails in numerous pathological states, such as immobilization, denervated conditions, neuromuscular disease, aging, AIDS, cancer, and diabetes.
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Affiliation(s)
- Anthony M. J. Sanchez
- INRA, UMR866 Dynamique Musculaire Et Métabolisme, Université Montpellier 1, 2 Place Viala, 34060 Montpellier, France
- Faculté des Sciences du Sport, Université Montpellier 1, 700 avenue du Pic Saint Loup, 34090 Montpellier, France
| | - Robin B. Candau
- INRA, UMR866 Dynamique Musculaire Et Métabolisme, Université Montpellier 1, 2 Place Viala, 34060 Montpellier, France
- Faculté des Sciences du Sport, Université Montpellier 1, 700 avenue du Pic Saint Loup, 34090 Montpellier, France
| | - Henri Bernardi
- INRA, UMR866 Dynamique Musculaire Et Métabolisme, Université Montpellier 1, 2 Place Viala, 34060 Montpellier, France
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Wu YJ, Fang YH, Chi HC, Chang LC, Chung SY, Huang WC, Wang XW, Lee KW, Chen SL. Insulin and LiCl synergistically rescue myogenic differentiation of FoxO1 over-expressed myoblasts. PLoS One 2014; 9:e88450. [PMID: 24551104 PMCID: PMC3923792 DOI: 10.1371/journal.pone.0088450] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 01/07/2014] [Indexed: 12/02/2022] Open
Abstract
Most recent studies reported that FoxO1 transcription factor was a negative regulator of myogenesis under serum withdrawal condition, a situation not actually found in vivo. Therefore, the role of FoxO1 in myogenesis should be re-examined under more physiologically relevant conditions. Here we found that FoxO1 was preferentially localized to nucleus in proliferating (PMB) and confluent myoblasts (CMB) and its nuclear exclusion was a prerequisite for formation of multinucleated myotubes (MT). The nuclear shuttling of FoxO1 in PMB could be prevented by leptomycin B and we further found that cytoplasmic accumulation of FoxO1 in myotubes was caused by the blockade of its nuclear import. Although over-expression of wildtype FoxO1 in C2C12 myoblasts significantly blocked their myogenic differentiation under serum withdrawal condition, application of insulin and LiCl, an activator of Wnt signaling pathway, to these cells successfully rescued their myogenic differentiation and generated myotubes with larger diameters. Interestingly, insulin treatment significantly reduced FoxO1 level and also delayed nuclear re-accumulation of FoxO1 triggered by mitogen deprivation. We further found that FoxO1 directly repressed the promoter activity of myogenic genes and this repression can be relieved by insulin and LiCl treatment. These results suggest that FoxO1 inhibits myogenesis in serum withdrawal condition but turns into a hypertrophy potentiator when other myogenic signals, such as Wnt and insulin, are available.
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Affiliation(s)
- Yi Ju Wu
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Yen Hsin Fang
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Hsiang Cheng Chi
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Li Chiung Chang
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Shih Ying Chung
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Wei Chieh Huang
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Xiao Wen Wang
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Kuan Wei Lee
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Shen Liang Chen
- Department of Life Sciences, National Central University, Jhongli, Taiwan
- * E-mail:
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Wang P, Drackley J, Stamey-Lanier J, Keisler D, Loor J. Effects of level of nutrient intake and age on mammalian target of rapamycin, insulin, and insulin-like growth factor-1 gene network expression in skeletal muscle of young Holstein calves. J Dairy Sci 2014; 97:383-91. [DOI: 10.3168/jds.2013-7042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/15/2013] [Indexed: 11/19/2022]
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Wu T, Zhang Z, Yuan Z, Lo LJ, Chen J, Wang Y, Peng J. Distinctive genes determine different intramuscular fat and muscle fiber ratios of the longissimus dorsi muscles in Jinhua and landrace pigs. PLoS One 2013; 8:e53181. [PMID: 23301040 PMCID: PMC3536781 DOI: 10.1371/journal.pone.0053181] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 11/26/2012] [Indexed: 02/04/2023] Open
Abstract
Meat quality is determined by properties such as carcass color, tenderness and drip loss. These properties are closely associated with meat composition, which includes the types of muscle fiber and content of intramuscular fat (IMF). Muscle fibers are the main contributors to meat mass, while IMF not only contributes to the sensory properties but also to the plethora of physical, chemical and technological properties of meat. However, little is known about the molecular mechanisms that determine meat composition in different pig breeds. In this report we show that Jinhua pigs, a Chinese breed, contains much higher levels of IMF than do Landrace pigs, a Danish breed. We analyzed global gene expression profiles in the longissimus dorsi muscles in Jinhua and Landrace breeds at the ages of 30, 90 and 150 days. Cross-comparison analysis revealed that genes that regulate fatty acid biosynthesis (e.g., fatty acid synthase and stearoyl-CoA desaturase) are expressed at higher levels in Jinhua pigs whereas those that regulate myogenesis (e.g., myogenic factor 6 and forkhead box O1) are expressed at higher levels in Landrace pigs. Among those genes which are highly expressed in Jinhua pigs at 90 days (d90), we identified a novel gene porcine FLJ36031 (pFLJ), which functions as a positive regulator of fat deposition in cultured intramuscular adipocytes. In summary, our data showed that the up-regulation of fatty acid biosynthesis regulatory genes such as pFLJ and myogenesis inhibitory genes such as myostatin in the longissimus dorsi muscles of Jinhua pigs could explain why this local breed produces meat with high levels of IMF.
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Affiliation(s)
- Ting Wu
- Key Laboratory for Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Zhenhai Zhang
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York, United States of America
| | - Zhangqin Yuan
- Key Laboratory for Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Li Jan Lo
- Key Laboratory for Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Jun Chen
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yizhen Wang
- Key Laboratory for Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Jinrong Peng
- Key Laboratory for Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
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Ge Y, Chen J. Mammalian target of rapamycin (mTOR) signaling network in skeletal myogenesis. J Biol Chem 2012; 287:43928-35. [PMID: 23115234 DOI: 10.1074/jbc.r112.406942] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mammalian (or mechanistic) target of rapamycin (mTOR) regulates a wide range of cellular and developmental processes by coordinating signaling responses to mitogens, nutrients, and various stresses. Over the last decade, mTOR has emerged as a master regulator of skeletal myogenesis, controlling multiple stages of the myofiber formation process. In this minireview, we present an emerging view of the signaling network underlying mTOR regulation of myogenesis, which contrasts with the well established mechanisms in the regulation of cell and muscle growth. Current questions for future studies are also highlighted.
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Affiliation(s)
- Yejing Ge
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Maltin CA. Muscle development and obesity: Is there a relationship? Organogenesis 2012; 4:158-69. [PMID: 19279728 DOI: 10.4161/org.4.3.6312] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Accepted: 05/20/2008] [Indexed: 12/25/2022] Open
Abstract
The formation of skeletal muscle from the epithelial somites involves a series of events triggered by temporally and spatially discrete signals resulting in the generation of muscle fibers which vary in their contractile and metabolic nature. The fiber type composition of muscles varies between individuals and it has now been found that there are differences in fiber type proportions between lean and obese animals and humans. Amongst the possible causes of obesity, it has been suggested that inappropriate prenatal environments may 'program' the fetus and may lead to increased risks for disease in adult life. The characteristics of muscle are both heritable and plastic, giving the tissue some ability to adapt to signals and stimuli both pre and postnatally. Given that muscle is a site of fatty acid oxidation and carbohydrate metabolism and that its development can be changed by prenatal events, it is interesting to examine the possible relationship between muscle development and the risk of obesity.
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Affiliation(s)
- Charlotte A Maltin
- School of Pharmacy and Life Sciences; Robert Gordon University; Aberdeen UK
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Ro SH, Liu D, Yeo H, Paik JH. FoxOs in neural stem cell fate decision. Arch Biochem Biophys 2012; 534:55-63. [PMID: 22902436 DOI: 10.1016/j.abb.2012.07.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 07/30/2012] [Accepted: 07/31/2012] [Indexed: 02/07/2023]
Abstract
Neural stem cells (NSCs) persist over the lifespan of mammals to give rise to committed progenitors and their differentiated cells in order to maintain the brain homeostasis. To this end, NSCs must be able to self-renew and otherwise maintain their quiescence. Suppression of aberrant proliferation or undesired differentiation is crucial to preclude either malignant growth or precocious depletion of NSCs. The PI3K-Akt-FoxO signaling pathway plays a central role in the regulation of multiple stem cells including one in the mammalian brain. In particular, members of FoxO family transcription factors are highly expressed in these stem cells. As an important downstream effector of growth, differentiation, and stress stimuli, mammalian FoxO transcription factor family controls cellular proliferation, oxidative stress response, homeostasis, and eventual maintenance of long-term repopulating potential. The review will focus on the current understanding of FoxO function in NSCs as well as discuss their biological activities that contribute to determining neural stem cell fate.
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Affiliation(s)
- Seung-Hyun Ro
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA
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Guo L, Xie B, Mao Z. Autophagy in premature senescent cells is activated via AMPK pathway. Int J Mol Sci 2012; 13:3563-3582. [PMID: 22489168 PMCID: PMC3317728 DOI: 10.3390/ijms13033563] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 02/23/2012] [Accepted: 03/06/2012] [Indexed: 12/18/2022] Open
Abstract
Autophagy is a highly regulated intracellular process involved in the turnover of most cellular constituents and in the maintenance of cellular homeostasis. In this study, we show that the activity of autophagy increases in H2O2 or RasV12-induced senescent fibroblasts. Inhibiting autophagy promotes cell apoptosis in senescent cells, suggesting that autophagy activation plays a cytoprotective role. Furthermore, our data indicate that the increase of autophagy in senescent cells is linked to the activation of transcription factor FoxO3A, which blocks ATP generation by transcriptionally up-regulating the expression of PDK4, an inhibitor of pyruvate dehydrogenase complex, thus leading to AMPK activation and mTOR inhibition. These findings suggest a novel mechanism by which FoxO3A factors can activate autophagy via metabolic alteration.
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Affiliation(s)
- Liujing Guo
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China; E-Mails:
| | - Bushan Xie
- Department of Gastroenterology, the First Affiliated Hospital of Nanchang University, Nanchang 330006, China; E-Mail:
| | - Zebin Mao
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China; E-Mails:
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +86-10-82805138
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Caron MA, Debigaré R, Dekhuijzen PNR, Maltais F. [Diaphragm and skeletal muscle dysfunction in COPD]. Rev Mal Respir 2011; 28:1250-64. [PMID: 22152934 DOI: 10.1016/j.rmr.2011.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 04/04/2011] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Chronic obstructive pulmonary disease (COPD) is often accompanied by skeletal muscle alterations, resulting in enhanced morbidity and mortality. STATE OF THE ART Many studies have highlighted important structural and biochemical modifications in limb and respiratory muscles in COPD. Reviewing the similarities and differences between the two most studied muscles in COPD, the quadriceps and the diaphragm, may provide important clues about the mechanisms dictating muscle changes that occur in this disease. PERSPECTIVES Though these two muscle groups share a common systemic environment, discrepancies are observed in their respective alterations. These phenotypic differences suggest that, in addition to systemic factors, the local microenvironment must participate in the reorganization seen in these two muscles in COPD. CONCLUSIONS The current review introduces the alterations observed in the quadriceps and diaphragm in the context of COPD and suggests possible signaling pathways involved in the development of muscle dysfunction.
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Affiliation(s)
- M-A Caron
- Centre de recherche, institut universitaire de cardiologie et de pneumologie de Québec, université Laval, 2725 chemin Ste-Foy, Québec, Canada
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Goodman CA, Mayhew DL, Hornberger TA. Recent progress toward understanding the molecular mechanisms that regulate skeletal muscle mass. Cell Signal 2011; 23:1896-906. [PMID: 21821120 PMCID: PMC3744211 DOI: 10.1016/j.cellsig.2011.07.013] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 07/15/2011] [Indexed: 01/30/2023]
Abstract
The maintenance of muscle mass is critical for health and issues associated with the quality of life. Over the last decade, extensive progress has been made with regard to our understanding of the molecules that regulate skeletal muscle mass. Not surprisingly, many of these molecules are intimately involved in the regulation of protein synthesis and protein degradation [e.g. the mammalian target of rapamycin (mTOR), eukaryotic initiation factor 2B (eIF2B), eukaryotic initiation factor 3f (eIF3f) and the forkhead box O (FoxO) transcription factors]. It is also becoming apparent that molecules which sense, or control, the energetic status of the cell play a key role in the regulation of muscle mass [e.g. AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor gamma coactivator-1 α (PGC1α)]. In this review we will attempt to summarize the current knowledge of how these molecules regulate skeletal muscle mass.
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Affiliation(s)
- Craig A Goodman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin Madison, Madison, WI 53706, USA.
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Reed SA, Sandesara PB, Senf SM, Judge AR. Inhibition of FoxO transcriptional activity prevents muscle fiber atrophy during cachexia and induces hypertrophy. FASEB J 2011; 26:987-1000. [PMID: 22102632 DOI: 10.1096/fj.11-189977] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cachexia is characterized by inexorable muscle wasting that significantly affects patient prognosis and increases mortality. Therefore, understanding the molecular basis of this muscle wasting is of significant importance. Recent work showed that components of the forkhead box O (FoxO) pathway are increased in skeletal muscle during cachexia. In the current study, we tested the physiological significance of FoxO activation in the progression of muscle atrophy associated with cachexia. FoxO-DNA binding dependent transcription was blocked in the muscles of mice through injection of a dominant negative (DN) FoxO expression plasmid prior to inoculation with Lewis lung carcinoma cells or the induction of sepsis. Expression of DN FoxO inhibited the increased mRNA levels of atrogin-1, MuRF1, cathepsin L, and/or Bnip3 and inhibited muscle fiber atrophy during cancer cachexia and sepsis. Interestingly, during control conditions, expression of DN FoxO decreased myostatin expression, increased MyoD expression and satellite cell proliferation, and induced fiber hypertrophy, which required de novo protein synthesis. Collectively, these data show that FoxO-DNA binding-dependent transcription is necessary for normal muscle fiber atrophy during cancer cachexia and sepsis, and further suggest that basal levels of FoxO play an important role during normal conditions to depress satellite cell activation and limit muscle growth.
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Affiliation(s)
- Sarah A Reed
- Department of Physical Therapy, 101 S. Newell Dr., University of Florida, Gainesville, FL 32611, USA
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Hakuno F, Yamauchi Y, Kaneko G, Yoneyama Y, Nakae J, Chida K, Kadowaki T, Yamanouchi K, Nishihara M, Takahashi SI. Constitutive expression of insulin receptor substrate (IRS)-1 inhibits myogenic differentiation through nuclear exclusion of Foxo1 in L6 myoblasts. PLoS One 2011; 6:e25655. [PMID: 21991327 PMCID: PMC3185002 DOI: 10.1371/journal.pone.0025655] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/09/2011] [Indexed: 11/19/2022] Open
Abstract
Insulin-like growth factors (IGFs) are well known to play essential roles in enhancement of myogenic differentiation. In this report we showed that initial IGF-I signal activation but long-term IGF-1 signal termination are required for myogenic differentiation. L6 myoblast stably transfected with myc-epitope tagged insulin receptor substrate-1, myc-IRS-1 (L6-mIRS1) was unable to differentiate into myotubes, indicating that IRS-1 constitutive expression inhibited myogenesis. To elucidate the molecular mechanisms underlying myogenic inhibition, IGF-I signaling was examined. IGF-I treatment of control L6 cells for 18 h resulted in a marked suppression of IGF-I stimulated IRS-1 association with the p85 PI 3-kinase and suppression of activation of Akt that correlated with a down regulation of IRS-1 protein. L6-mIRS1 cells, in contrast, had sustained high levels of IRS-1 protein following 18 h of IGF-I treatment with persistent p85 PI 3-kinase association with IRS-1, Akt phosphorylation and phosphorylation of the downstream Akt substrate, Foxo1. Consistent with Foxo1 phosphorylation, Foxo1 protein was excluded from the nuclei in L6-mIRS1 cells, whereas Foxo1 was localized in the nuclei in control L6 cells during induction of differentiation. In addition, L6 cells stably expressing a dominant-interfering form of Foxo1, Δ256Foxo1 (L6-Δ256Foxo1) were unable to differentiate into myotubes. Together, these data demonstrate that IGF-I regulation of Foxo1 nuclear localization is essential for the myogenic program in L6 cells but that persistent activation of IGF-1 signaling pathways results in a negative feedback to prevent myogenesis.
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Affiliation(s)
- Fumihiko Hakuno
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yoko Yamauchi
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Gen Kaneko
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yosuke Yoneyama
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Jun Nakae
- Frontier Medicine on Metabolic Syndrome, Division of Endocrinology, Metabolism and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan
| | - Kazuhiro Chida
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Tatsuhiko Kadowaki
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Keitaro Yamanouchi
- Department of Veterinary Medical Science, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Masugi Nishihara
- Department of Veterinary Medical Science, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Shin-Ichiro Takahashi
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- * E-mail:
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Reed SA, Senf SM, Cornwell EW, Kandarian SC, Judge AR. Inhibition of IkappaB kinase alpha (IKKα) or IKKbeta (IKKβ) plus forkhead box O (Foxo) abolishes skeletal muscle atrophy. Biochem Biophys Res Commun 2011; 405:491-6. [PMID: 21256828 DOI: 10.1016/j.bbrc.2011.01.059] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/17/2011] [Indexed: 10/18/2022]
Abstract
Two transcription factor families that are activated during multiple conditions of skeletal muscle wasting are nuclear factor κB (NF-κB) and forkhead box O (Foxo). There is clear evidence that both NF-κB and Foxo activation are sufficient to cause muscle fiber atrophy and they are individually required for at least half of the fiber atrophy during muscle disuse, but there is no work determining the combined effect of inhibiting these factors during a physiological condition of muscle atrophy. Here, we determined whether inhibition of Foxo activation plus inhibition of NF-κB activation, the latter by blocking the upstream inhibitor of kappaB kinases (IKKα and IKKβ), would prevent muscle atrophy induced by 7 days of cast immobilization. Results were based on measurements of mean fiber cross-sectional area (CSA) from 72 muscles transfected with 5 different mutant expression plasmids or plasmid combinations. Immobilization caused a 47% decrease in fiber CSA in muscles injected with control plasmids. Fibers from immobilized muscles transfected with dominant negative (d.n.) IKKα-EGFP, d.n. IKKβ-EGFP or d.n. Foxo-DsRed showed a 22%, 57%, and 76% inhibition of atrophy, respectively. Co-expression of d.n. IKKα-EGFP and d.n. Foxo-DsRed significantly inhibited 89% of the immobilization-induced fiber atrophy. Similarly, co-expression of d.n. IKKβ-EGFP and d.n. Foxo-DsRed inhibited the immobilization-induced fiber atrophy by 95%. These findings demonstrate that the combined effects of inhibiting immobilization-induced NF-κB and Foxo transcriptional activity has an additive effect on preventing immobilization-induced atrophy, indicating that NF-κB and Foxo have a cumulative effect on atrophy signaling and/or atrophy gene expression.
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Affiliation(s)
- S A Reed
- Department of Physical Therapy, University of Florida, 101 S. Newell Drive, Gainesville, FL 32610, USA
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Zhang Y, Zhang HM, Shi Y, Lustgarten M, Li Y, Qi W, Zhang BX, Van Remmen H. Loss of manganese superoxide dismutase leads to abnormal growth and signal transduction in mouse embryonic fibroblasts. Free Radic Biol Med 2010; 49:1255-62. [PMID: 20638473 PMCID: PMC3418666 DOI: 10.1016/j.freeradbiomed.2010.07.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 06/18/2010] [Accepted: 07/09/2010] [Indexed: 10/19/2022]
Abstract
Manganese superoxide dismutase (MnSOD) in the mitochondria plays an important role in cellular defense against oxidative damage. Homozygous MnSOD knockout (Sod2(-/-)) mice are neonatal lethal, indicating the essential role of MnSOD in early development. To investigate the potential cellular abnormalities underlying the aborted development of Sod2(-/-) mice, we examined the growth of isolated mouse embryonic fibroblasts (MEFs) from Sod2(-/-) mice. We found that the proliferation of Sod2(-/-) MEFs was significantly decreased compared with wild-type MEFs despite the absence of morphological differences. The Sod2(-/-) MEFs produced less cellular ATP, had lower O(2) consumption, generated more superoxide, and expressed less Prdx3 protein. Furthermore, the loss of MnSOD dramatically altered several markers involved in cell proliferation and growth, including decreased growth stimulatory function of mTOR signaling and enhanced growth inhibitory function of GSK-3β signaling. Interestingly, the G-protein-coupled receptor-mediated intracellular Ca(2+) signal transduction was also severely suppressed in Sod2(-/-) MEFs. Finally, the ratio of microtubule-associated protein light chain 3 (LC3)-II/LC3-I, an index of autophagic activity, was increased in Sod2(-/-) MEFs, consistent with a reduction in mTOR signal transduction. These data demonstrate that MnSOD deficiency results in alterations in several key signaling pathways, which may contribute to the lethal phenotype of Sod2(-/-) mice.
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Affiliation(s)
- Yiqiang Zhang
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
- South Texas Veterans Health Care System, San Antonio, Texas 78229
| | - Hong-Mei Zhang
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Yun Shi
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Michael Lustgarten
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Yan Li
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Wenbo Qi
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Bin-Xian Zhang
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Holly Van Remmen
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
- South Texas Veterans Health Care System, San Antonio, Texas 78229
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Rapamycin suppresses the expansion and differentiation of porcine neonatal pancreas cell clusters. Transplantation 2010; 90:717-24. [PMID: 20622751 DOI: 10.1097/tp.0b013e3181eceaaf] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND The role of rapamycin in pancreas stem cells remains to be clearly elucidated. Herein, we evaluated the effects of rapamycin on porcine neonatal pancreas cell clusters (NPCCs), which primarily comprised pancreatic precursors, and attempted to find an intracellular mechanism about the harmful effects of rapamycin. METHODS Porcine NPCCs were treated with rapamycin in a monolayer, and the apoptosis and proliferation were determined via caspase-3 assay and H-thymidine uptake analysis. The expression of transcription factors was assessed via reverse-transcriptase polymerase chain reaction and Western blotting. For the in vivo study, the porcine NPCCs were transplanted into the kidney subcapsules of normal nude mice and treated with rapamycin. RESULTS Rapamycin treatment significantly reduced the number of β cells, glucose-stimulated insulin secretion, and the insulin contents in the monolayer-cultured porcine NPCCs. Furthermore, rapamycin treatment increased the apoptosis and inhibited the proliferation of β cells in the culture dishes. The expressions of the insulin, pancreatic and duodenal homeobox-1, and NeuroD/Beta2 genes were down-regulated via rapamycin treatment. The expression of insulin-like growth factor-II was significantly down-regulated, but the expression of Foxo1 was simultaneously inversely increased, and the translocation of Foxo1 from the cytoplasm to the nucleus was induced by rapamycin treatment. Moreover, rapamycin treatment induced a marked reduction in the relative volume and absolute mass of β cells in the porcine NPCCs grafts at 8 weeks after transplantation in the normal nude mice. CONCLUSIONS Here, we demonstrate that rapamycin treatment suppresses the expansion and differentiation of porcine NPCCs, and the alteration of Foxo1 and insulin-like growth factor-II gene expression might be the crucial factors.
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Qin W, Pan J, Bauman WA, Cardozo CP. Differential alterations in gene expression profiles contribute to time-dependent effects of nandrolone to prevent denervation atrophy. BMC Genomics 2010; 11:596. [PMID: 20969782 PMCID: PMC3091741 DOI: 10.1186/1471-2164-11-596] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 10/22/2010] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Anabolic steroids, such as nandrolone, slow muscle atrophy, but the mechanisms responsible for this effect are largely unknown. Their effects on muscle size and gene expression depend upon time, and the cause of muscle atrophy. Administration of nandrolone for 7 days beginning either concomitantly with sciatic nerve transection (7 days) or 29 days later (35 days) attenuated denervation atrophy at 35 but not 7 days. We reasoned that this model could be used to identify genes that are regulated by nandrolone and slow denervation atrophy, as well as genes that might explain the time-dependence of nandrolone effects on such atrophy. Affymetrix microarrays were used to profile gene expression changes due to nandrolone at 7 and 35 days and to identify major gene expression changes in denervated muscle between 7 and 35 days. RESULTS Nandrolone selectively altered expression of 124 genes at 7 days and 122 genes at 35 days, with only 20 genes being regulated at both time points. Marked differences in biological function of genes regulated by nandrolone at 7 and 35 days were observed. At 35, but not 7 days, nandrolone reduced mRNA and protein levels for FOXO1, the mTOR inhibitor REDD2, and the calcineurin inhibitor RCAN2 and increased those for ApoD. At 35 days, correlations between mRNA levels and the size of denervated muscle were negative for RCAN2, and positive for ApoD. Nandrolone also regulated genes for Wnt signaling molecules. Comparison of gene expression at 7 and 35 days after denervation revealed marked alterations in the expression of 9 transcriptional coregulators, including Ankrd1 and 2, and many transcription factors and kinases. CONCLUSIONS Genes regulated in denervated muscle after 7 days administration of nandrolone are almost entirely different at 7 versus 35 days. Alterations in levels of FOXO1, and of genes involved in signaling through calcineurin, mTOR and Wnt may be linked to the favorable action of nandrolone on denervated muscle. Marked changes in the expression of genes regulating transcription and intracellular signaling may contribute to the time-dependent effects of nandrolone on gene expression.
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Affiliation(s)
- Weiping Qin
- Center of Excellence for the Medical Consequences of Spinal Cord Injury1, Room 1E-02, James J. Peters VA Medical Center, 130 West Kingsbridge Road, Bronx, New York 10468, USA
- Department of Medicine, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, New York 10029, USA
| | - Jiangping Pan
- Center of Excellence for the Medical Consequences of Spinal Cord Injury1, Room 1E-02, James J. Peters VA Medical Center, 130 West Kingsbridge Road, Bronx, New York 10468, USA
| | - William A Bauman
- Center of Excellence for the Medical Consequences of Spinal Cord Injury1, Room 1E-02, James J. Peters VA Medical Center, 130 West Kingsbridge Road, Bronx, New York 10468, USA
- Department of Medicine, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, New York 10029, USA
- Department of Rehabilitation Medicine, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, New York 10029, USA
| | - Christopher P Cardozo
- Center of Excellence for the Medical Consequences of Spinal Cord Injury1, Room 1E-02, James J. Peters VA Medical Center, 130 West Kingsbridge Road, Bronx, New York 10468, USA
- Department of Medicine, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, New York 10029, USA
- Department of Rehabilitation Medicine, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, New York 10029, USA
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Wu Y, Zhao W, Zhao J, Zhang Y, Qin W, Pan J, Bauman WA, Blitzer RD, Cardozo C. REDD1 is a major target of testosterone action in preventing dexamethasone-induced muscle loss. Endocrinology 2010; 151:1050-9. [PMID: 20032058 PMCID: PMC2840688 DOI: 10.1210/en.2009-0530] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Glucocorticoids are a well-recognized and common cause of muscle atrophy that can be prevented by testosterone. However, the molecular mechanisms underlying such protection have not been described. Thus, the global effects of testosterone on dexamethasone-induced changes in gene expression were evaluated in rat gastrocnemius muscle using DNA microarrays. Gene expression was analyzed after 7-d administration of dexamethasone, dexamethasone plus testosterone, or vehicle. Dexamethasone changed expression of 876 probe sets by at least 2-fold. Among these, 474 probe sets were changed by at least 2-fold in the opposite direction in the dexamethasone plus testosterone group (genes in opposition). Major biological themes represented by genes in opposition included IGF-I signaling, myogenesis and muscle development, and cell cycle progression. Testosterone completely prevented the 22-fold increase in expression of the mammalian target of rapamycin (mTOR) inhibitor regulated in development and DNA damage responses 1 (REDD1), and attenuated dexamethasone induced increased expression of eIF4E binding protein 1, Forkhead box O1, and the p85 regulatory subunit of the IGF-I receptor but prevented decreased expression of IRS-1. Testosterone attenuated increases in REDD1 protein in skeletal muscle and L6 myoblasts and prevented dephosphorylation of p70S6 kinase at the mTOR-dependent site Thr389 in L6 myoblast cells. Effects of testosterone on REDD1 mRNA levels occurred within 1 h, required the androgen receptor, were blocked by bicalutamide, and were due to inhibition of transcriptional activation of REDD1 by dexamethasone. These data suggest that testosterone blocks dexamethasone-induced changes in expression of REDD1 and other genes that collectively would otherwise down-regulate mTOR activity and hence also down-regulate protein synthesis.
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Affiliation(s)
- Yong Wu
- Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, 953 Southern Boulevard, Bronx, New York 10468, USA
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Wen J, Xia Q, Wang C, Liu W, Chen Y, Gao J, Gong Y, Yin B, Ke Y, Qiang B, Yuan J, Peng X. Dok-5 is involved in cardiomyocyte differentiation through PKB/FOXO3a pathway. J Mol Cell Cardiol 2009; 47:761-9. [DOI: 10.1016/j.yjmcc.2009.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 09/20/2009] [Accepted: 09/23/2009] [Indexed: 11/25/2022]
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Fu L, Kim YA, Wang X, Wu X, Yue P, Lonial S, Khuri FR, Sun SY. Perifosine inhibits mammalian target of rapamycin signaling through facilitating degradation of major components in the mTOR axis and induces autophagy. Cancer Res 2009; 69:8967-76. [PMID: 19920197 DOI: 10.1158/0008-5472.can-09-2190] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Perifosine is an alkylphospholipid exhibiting antitumor activity as shown in both preclinical studies and clinical trials. This activity is partly associated with its ability to inhibit Akt activity. It has been shown that the mammalian target of rapamycin (mTOR) axis plays a critical role in regulation of cell proliferation and survival primarily through functioning both downstream and upstream of Akt. The current study reveals a novel mechanism by which perifosine inhibits Akt and the mTOR axis. In addition to inhibition of Akt, perifosine inhibited the assembly of both mTOR/raptor and mTOR/rictor complexes. Strikingly, perifosine reduced the levels of Akt and other major components including mTOR, raptor, rictor, 70-kDa ribosomal S6 kinase, and 4E-binding protein 1 in the mTOR axis by promoting their degradation through a GSK3/FBW7-dependent mechanism. These results thus suggest that perifosine inhibits the mTOR axis through a different mechanism from inhibition of mTOR signaling by classic mTOR inhibitors such as rapamycin. Moreover, perifosine substantially increased the levels of type II light chain 3, a hallmark of autophagy, in addition to increasing poly(ADP-ribose) polymerase cleavage, suggesting that perifosine induces both apoptosis and autophagy. The combination of perifosine with a lysosomal inhibitor enhanced apoptosis and inhibited the growth of xenografts in nude mice, suggesting that perifosine-induced autophagy protects cells from undergoing apoptosis. Collectively, we conclude that perifosine inhibits mTOR signaling and induces autophagy, highlighting a novel mechanism accounting for the anticancer activity of perifosine and a potential strategy to enhance the anticancer efficacy of perifosine by preventing autophagy.
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Affiliation(s)
- Lei Fu
- Department of Hematology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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De Giovanni C, Landuzzi L, Nicoletti G, Lollini PL, Nanni P. Molecular and cellular biology of rhabdomyosarcoma. Future Oncol 2009; 5:1449-75. [DOI: 10.2217/fon.09.97] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Rhabdomyosarcoma is a group of soft-tissue sarcomas that share features of skeletal myogenesis, but show extensive heterogeneity in histology, age and site of onset, and prognosis. This review matches recent molecular data with biological features of rhabdomyosarcoma. Alterations in molecular pathways, animal models, cell of origin and potential new therapeutic targets are discussed.
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Affiliation(s)
- Carla De Giovanni
- Department of Experimental Pathology, Cancer Research Section, University of Bologna, Bologna, Italy
| | - Lorena Landuzzi
- Laboratory of Experimental Oncology, Rizzoli Orthopaedic Institute, Bologna, Italy
| | - Giordano Nicoletti
- Laboratory of Experimental Oncology, Rizzoli Orthopaedic Institute, Bologna, Italy
| | - Pier-Luigi Lollini
- Department of Hematology and Oncological Sciences ‘L. e A. Seragnoli’, Viale Filopanti 22, Bologna 40126, Italy
| | - Patrizia Nanni
- Department of Experimental Pathology, Cancer Research Section, University of Bologna, Bologna, Italy
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Pearen MA, Ryall JG, Lynch GS, Muscat GE. Expression profiling of skeletal muscle following acute and chronic beta2-adrenergic stimulation: implications for hypertrophy, metabolism and circadian rhythm. BMC Genomics 2009; 10:448. [PMID: 19772666 PMCID: PMC2758907 DOI: 10.1186/1471-2164-10-448] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 09/23/2009] [Indexed: 02/08/2023] Open
Abstract
Background Systemic administration of β-adrenoceptor (β-AR) agonists has been found to induce skeletal muscle hypertrophy and significant metabolic changes. In the context of energy homeostasis, the importance of β-AR signaling has been highlighted by the inability of β1-3-AR-deficient mice to regulate energy expenditure and susceptibility to diet induced obesity. However, the molecular pathways and gene expression changes that initiate and maintain these phenotypic modulations are poorly understood. Therefore, the aim of this study was to identify differential changes in gene expression in murine skeletal muscle associated with systemic (acute and chronic) administration of the β2-AR agonist formoterol. Results Skeletal muscle gene expression (from murine tibialis anterior) was profiled at both 1 and 4 hours following systemic administration of the β2-AR agonist formoterol, using Illumina 46K mouse BeadArrays. Illumina expression profiling revealed significant expression changes in genes associated with skeletal muscle hypertrophy, myoblast differentiation, metabolism, circadian rhythm, transcription, histones, and oxidative stress. Differentially expressed genes relevant to the regulation of muscle mass and metabolism (in the context of the hypertrophic phenotype) were further validated by quantitative RT-PCR to examine gene expression in response to both acute (1-24 h) and chronic administration (1-28 days) of formoterol at multiple timepoints. In terms of skeletal muscle hypertrophy, attenuation of myostatin signaling (including differential expression of myostatin, activin receptor IIB, phospho-Smad3 etc) was observed following acute and chronic administration of formoterol. Acute (but not chronic) administration of formoterol also significantly induced the expression of genes involved in oxidative metabolism, including hexokinase 2, sorbin and SH3 domain containing 1, and uncoupling protein 3. Interestingly, formoterol administration also appeared to influence some genes associated with the peripheral regulation of circadian rhythm (including nuclear factor interleukin 3 regulated, D site albumin promoter binding protein, and cryptochrome 2). Conclusion This is the first study to utilize gene expression profiling to examine global gene expression in response to acute β2-AR agonist treatment of skeletal muscle. In summary, systemic administration of a β2-AR agonist had a profound effect on global gene expression in skeletal muscle. In terms of hypertrophy, β2-AR agonist treatment altered the expression of several genes associated with myostatin signaling, a previously unreported effect of β-AR signaling in skeletal muscle. This study also demonstrates a β2-AR agonist regulation of circadian rhythm genes, indicating crosstalk between β-AR signaling and circadian cycling in skeletal muscle. Gene expression alterations discovered in this study provides insight into many of the underlying changes in gene expression that mediate β-AR induced skeletal muscle hypertrophy and altered metabolism.
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Affiliation(s)
- Michael A Pearen
- Institute for Molecular Bioscience, The University of Queensland, Queensland 4072, Australia.
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Sáinz N, Rodríguez A, Catalán V, Becerril S, Ramírez B, Gómez-Ambrosi J, Frühbeck G. Leptin administration favors muscle mass accretion by decreasing FoxO3a and increasing PGC-1alpha in ob/ob mice. PLoS One 2009; 4:e6808. [PMID: 19730740 PMCID: PMC2733298 DOI: 10.1371/journal.pone.0006808] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 07/31/2009] [Indexed: 12/26/2022] Open
Abstract
Absence of leptin has been associated with reduced skeletal muscle mass in leptin-deficient ob/ob mice. The aim of our study was to examine the effect of leptin on the catabolic and anabolic pathways regulating muscle mass. Gastrocnemius, extensor digitorum longus and soleus muscle mass as well as fiber size were significantly lower in ob/ob mice compared to wild type littermates, being significantly increased by leptin administration (P<0.001). This effect was associated with an inactivation of the muscle atrophy-related transcription factor forkhead box class O3 (FoxO3a) (P<0.05), and with a decrease in the protein expression levels of the E3 ubiquitin-ligases muscle atrophy F-box (MAFbx) (P<0.05) and muscle RING finger 1 (MuRF1) (P<0.05). Moreover, leptin increased (P<0.01) protein expression levels of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a regulator of muscle fiber type, and decreased (P<0.05) myostatin protein, a negative regulator of muscle growth. Leptin administration also activated (P<0.01) the regulators of cell cycle progression proliferating cell nuclear antigen (PCNA) and cyclin D1, and increased (P<0.01) myofibrillar protein troponin T. The present study provides evidence that leptin treatment may increase muscle mass of ob/ob mice by inhibiting myofibrillar protein degradation as well as enhancing muscle cell proliferation.
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Affiliation(s)
- Neira Sáinz
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Amaia Rodríguez
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Victoria Catalán
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Sara Becerril
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Beatriz Ramírez
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Gema Frühbeck
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- Department of Endocrinology, Clínica Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- * E-mail:
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Regulation of myoblast differentiation by the nuclear envelope protein NET39. Mol Cell Biol 2009; 29:5800-12. [PMID: 19704009 DOI: 10.1128/mcb.00684-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recently, several transmembrane proteins of the nuclear envelope have been implicated in regulation of signaling and gene expression. Here we demonstrate that the nuclear lamina-associated nuclear envelope transmembrane protein NET39 (Ppapdc3) functions as a negative regulator of myoblast differentiation, in part through effects on mTOR signaling. We found that NET39 is highly expressed in cardiac and skeletal muscle tissues and becomes strongly upregulated during cultured myoblast differentiation. Knockdown of NET39 by RNA interference in myoblasts strongly promoted differentiation, whereas overexpression of NET39 repressed myogenesis. Proteomic analysis of NET39 complexes immunoprecipitated from myotubes, in combination with other methods, identified mTOR as an interaction partner of NET39. We found that ectopic expression of NET39 in myoblasts negatively regulated myogenesis by diminishing mTOR activity, which in turn decreased insulin-like growth factor II production and autocrine signaling. Our results indicate that NET39 is part of the regulatory machinery for myogenesis and raise the possibility that it may be important for muscle homeostasis.
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Yuasa K, Masuda T, Yoshikawa C, Nagahama M, Matsuda Y, Tsuji A. Subtilisin-like proprotein convertase PACE4 is required for skeletal muscle differentiation. J Biochem 2009; 146:407-15. [PMID: 19520771 DOI: 10.1093/jb/mvp090] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Most growth factors stimulate myoblast proliferation and prevent differentiation, whereas insulin-like growth factors (IGFs) promote myoblast differentiation through the phosphatidylinositol 3-kinase (PI3K) pathway. Subtilisin-like proprotein convertases (SPCs) are involved in cell growth and differentiation via activation of pro-growth factors. However, the role of SPCs in myogenesis remains poorly understood. Here we show that PACE4, a member of the SPC family, plays a critical role in myogenic differentiation of C2C12 cells. PACE4 mRNA levels increased markedly during myogenesis, whereas the expression of other member of SPC family, furin and PC6, remained unchanged. The expression pattern of pro-IGF-II, which is processed extracellularly by SPCs, was similar to that of PACE4. The expression of shRNA targeting PACE4, but not furin, suppressed the expression of the muscle-specific myosin light chain (MLC). Interestingly, reduced expression of MLC was restored following treatment with recombinant mature IGF-II. Finally, we demonstrated that the PI3K inhibitor LY294002 blocked the induction of PACE4 mRNA, a result not observed when another myogenic differentiation inhibitor, SB203580 (p38 MAP kinase inhibitor), was employed, indicating the presence of a positive feedback loop regulating PACE4 expression. These results suggest that PACE4 plays an important role in myogenic differentiation through its association with the IGF-II pathway.
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Affiliation(s)
- Keizo Yuasa
- Department of Biological Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima, Tokushima 770-8506, Japan
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45
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Abstract
Forkhead box O (FOXO) transcription factors play an important role in modulating metabolic functions. FOXO is regulated by several modifications, but one of the most critical is phosphorylation and nuclear exclusion by Akt. Given the impact of insulin signaling on Akt-mediated phosphorylation of FOXO and the relatively high expression of Foxo1 in insulin-responsive tissues, this transcription factor is highly poised to regulate energy metabolism. When nutrient and insulin levels are low, Foxo1 promotes expression of gluconeogenic enzymes. Conversely, in the fed state, insulin levels rise and stimulate uptake of glucose primarily into skeletal muscle and other organs, including adipose tissue. Under certain pathophysiologic conditions, including insulin resistance, negative signaling to Foxo1 is compromised. Further clarification of the role of Foxo1 in insulin-responsive tissues will strengthen our understanding and allow us to better combat insulin resistance and diabetes mellitus.
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Affiliation(s)
- Danielle N Gross
- University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
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46
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Caron MA, Debigaré R, Dekhuijzen PNR, Maltais F. Comparative assessment of the quadriceps and the diaphragm in patients with COPD. J Appl Physiol (1985) 2009; 107:952-61. [PMID: 19359618 DOI: 10.1152/japplphysiol.00194.2009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic obstructive pulmonary disease (COPD) and other chronic diseases such as heart failure are accompanied by skeletal muscle alterations that further enhance morbidity and mortality in affected individuals. Several studies have highlighted important structural and biochemical modifications in limb and respiratory muscles in COPD. Reviewing the similarities and differences between the two most studied muscles in COPD, the quadriceps and the diaphragm, may be helpful in providing important clues about the mechanisms underlying muscle changes associated with this disease. Although oxidative stress is present in both muscles, other muscle alterations are clearly distinct between the quadriceps and the diaphragm. For example, the oxidative metabolism varies in opposite directions, the diaphragm exhibiting increased resistance to fatigue while the quadriceps in COPD is characterized by premature fatigability. Differences in muscle phenotypic expression between the diaphragm and the quadriceps indicate that, in addition to systemic factors, the local microenvironment must participate in the reorganization seen in these two skeletal muscles in COPD.
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Affiliation(s)
- Marc-André Caron
- Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, Canada G1V 4G5
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Abstract
PURPOSE OF REVIEW Cancer cachexia is associated with marked alterations in skeletal muscle protein metabolism that lead to muscle wasting and, in some cases, death. The inflammatory response elicited by cancer is a likely, if not primary, mediator of these alterations. This review focuses on the possible relationship between inflammatory signaling and altered amino acid metabolism in cancer. RECENT FINDINGS Loss of skeletal muscle in cancer patients can potentially be due to anorexia and early satiety, reduced muscle protein synthesis, and/or increased muscle protein breakdown. Inflammation has been associated with each of these mechanisms. Effects on appetite appear to be mediated by the melanocortin system in the hypothalamus. Studies in animal models of cachexia suggest that modulation of orexigenic and anorexigenic pathways in this system may improve nutrient consumption. Inflammatory cytokines such as IL-6 and TNF-alpha are likely to contribute to the effects of inflammation on muscle protein metabolism through several pathways. SUMMARY Limited studies in humans suggest that targeted anti-inflammatory and nutritional interventions may ameliorate the net catabolic effect on skeletal muscle protein metabolism. Future studies of the precise mechanism of muscle protein loss, as well as novel or combination therapies to inhibit inflammation and promote anabolism, are warranted.
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Affiliation(s)
- William J Durham
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA
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48
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Current world literature. Ageing: biology and nutrition. Curr Opin Clin Nutr Metab Care 2009; 12:95-100. [PMID: 19057195 DOI: 10.1097/mco.0b013e32831fd97a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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49
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Abstract
Very low-density lipoproteins (VLDL) are triglyceride-rich particles. VLDL is synthesized in hepatocytes and secreted from the liver in a pathway that is tightly regulated by insulin. Hepatic VLDL production is stimulated in response to reduced insulin action, resulting in increased release of VLDL into the blood under fasting conditions. Circulating VLDL serves as a vehicle for transporting lipids to peripheral tissues for energy homeostasis. Conversely, hepatic VLDL production is suppressed in response to increased insulin release after meals. This effect is critical for preventing prolonged excursion of postprandial plasma lipid profiles in normal individuals. In subjects with obesity and type 2 diabetes, the ability of insulin to regulate VLDL production becomes impaired due to insulin resistance in the liver, resulting in excessive VLDL secretion and accumulation of triglyceride-rich particles in the blood. Such abnormality in lipid metabolism characterizes the pathogenesis of hypertriglyceridemia and accounts for increased risk of coronary artery disease in obesity and type 2 diabetes. Nevertheless, the molecular basis that links insulin resistance to VLDL overproduction remains poorly understood. Our recent studies illustrate that the forkhead transcription factor FoxO1 acts in the liver to integrate hepatic insulin action to VLDL production. Augmented FoxO1 activity in insulin resistant livers promotes hepatic VLDL overproduction and predisposes to the development of hypertriglyceridemia. These new findings raise an important question: Is FoxO1 a therapeutic target for ameliorating hypertriglyceridemia? Here we discuss this question in the context of recent advances toward our understanding of the pathophysiology of hypertriglyceridemia.
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Affiliation(s)
- Adama Kamagate
- Department of Pediatrics, Division of Immunogenetics, Rangos Research Center, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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