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Kang H, Park YK, Lee JY, Bae M. Roles of Histone Deacetylase 4 in the Inflammatory and Metabolic Processes. Diabetes Metab J 2024; 48:340-353. [PMID: 38514922 PMCID: PMC11140402 DOI: 10.4093/dmj.2023.0174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 02/07/2024] [Indexed: 03/23/2024] Open
Abstract
Histone deacetylase 4 (HDAC4), a class IIa HDAC, has gained attention as a potential therapeutic target in treating inflammatory and metabolic processes based on its essential role in various biological pathways by deacetylating non-histone proteins, including transcription factors. The activity of HDAC4 is regulated at the transcriptional, post-transcriptional, and post-translational levels. The functions of HDAC4 are tissue-dependent in response to endogenous and exogenous factors and their substrates. In particular, the association of HDAC4 with non-histone targets, including transcription factors, such as myocyte enhancer factor 2, hypoxia-inducible factor, signal transducer and activator of transcription 1, and forkhead box proteins, play a crucial role in regulating inflammatory and metabolic processes. This review summarizes the regulatory modes of HDAC4 activity and its functions in inflammation, insulin signaling and glucose metabolism, and cardiac muscle development.
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Affiliation(s)
- Hyunju Kang
- Department of Food and Nutrition, Keimyung University, Daegu, Korea
| | - Young-Ki Park
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT, USA
| | - Ji-Young Lee
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT, USA
| | - Minkyung Bae
- Department of Food and Nutrition, Yonsei University, Seoul, Korea
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2
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Tan WJ, Hawley HR, Wilson SJ, Fitzsimons HL. Deciphering the roles of subcellular distribution and interactions involving the MEF2 binding region, the ankyrin repeat binding motif and the catalytic site of HDAC4 in Drosophila neuronal morphogenesis. BMC Biol 2024; 22:2. [PMID: 38167120 PMCID: PMC10763444 DOI: 10.1186/s12915-023-01800-1] [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: 02/14/2023] [Accepted: 12/06/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Dysregulation of nucleocytoplasmic shuttling of histone deacetylase 4 (HDAC4) is associated with several neurodevelopmental and neurodegenerative disorders. Consequently, understanding the roles of nuclear and cytoplasmic HDAC4 along with the mechanisms that regulate nuclear entry and exit is an area of concerted effort. Efficient nuclear entry is dependent on binding of the transcription factor MEF2, as mutations in the MEF2 binding region result in cytoplasmic accumulation of HDAC4. It is well established that nuclear exit and cytoplasmic retention are dependent on 14-3-3-binding, and mutations that affect binding are widely used to induce nuclear accumulation of HDAC4. While regulation of HDAC4 shuttling is clearly important, there is a gap in understanding of how the nuclear and cytoplasmic distribution of HDAC4 impacts its function. Furthermore, it is unclear whether other features of the protein including the catalytic site, the MEF2-binding region and/or the ankyrin repeat binding motif influence the distribution and/or activity of HDAC4 in neurons. Since HDAC4 functions are conserved in Drosophila, and increased nuclear accumulation of HDAC4 also results in impaired neurodevelopment, we used Drosophila as a genetic model for investigation of HDAC4 function. RESULTS Here we have generated a series of mutants for functional dissection of HDAC4 via in-depth examination of the resulting subcellular distribution and nuclear aggregation, and correlate these with developmental phenotypes resulting from their expression in well-established models of neuronal morphogenesis of the Drosophila mushroom body and eye. We found that in the mushroom body, forced sequestration of HDAC4 in the nucleus or the cytoplasm resulted in defects in axon morphogenesis. The actions of HDAC4 that resulted in impaired development were dependent on the MEF2 binding region, modulated by the ankyrin repeat binding motif, and largely independent of an intact catalytic site. In contrast, disruption to eye development was largely independent of MEF2 binding but mutation of the catalytic site significantly reduced the phenotype, indicating that HDAC4 acts in a neuronal-subtype-specific manner. CONCLUSIONS We found that the impairments to mushroom body and eye development resulting from nuclear accumulation of HDAC4 were exacerbated by mutation of the ankyrin repeat binding motif, whereas there was a differing requirement for the MEF2 binding site and an intact catalytic site. It will be of importance to determine the binding partners of HDAC4 in nuclear aggregates and in the cytoplasm of these tissues to further understand its mechanisms of action.
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Affiliation(s)
- Wei Jun Tan
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Hannah R Hawley
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Sarah J Wilson
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Helen L Fitzsimons
- School of Natural Sciences, Massey University, Palmerston North, New Zealand.
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3
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Zhang P, Lu R. The Molecular and Biological Function of MEF2D in Leukemia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1459:379-403. [PMID: 39017853 DOI: 10.1007/978-3-031-62731-6_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Myocyte enhancer factor 2 (MEF2) is a key transcription factor (TF) in skeletal, cardiac, and neural tissue development and includes four isoforms: MEF2A, MEF2B, MEF2C, and MEF2D. These isoforms significantly affect embryonic development, nervous system regulation, muscle cell differentiation, B- and T-cell development, thymocyte selection, and effects on tumorigenesis and leukemia. This chapter describes the multifaceted roles of MEF2 family proteins, covering embryonic development, nervous system regulation, and muscle cell differentiation. It further elucidates the contribution of MEF2 to various blood and immune cell functions. Specifically, in B-cell precursor acute lymphoblastic leukemia (BCP-ALL), MEF2D is aberrantly expressed and forms a fusion protein with BCL9, CSF1R, DAZAP1, HNRNPUL1, and SS18. These fusion proteins are closely related to the pathogenesis of leukemia. In addition, it specifically introduces the regulatory effect of MEF2D fusion protein on the proliferation and growth of B-cell acute lymphoblastic leukemia (B-ALL) cells. Finally, we detail the positive feedback loop between MEF2D and IRF8 that significantly promotes the progression of acute myeloid leukemia (AML) and the importance of the ZMYND8-BRD4 interaction in regulating the IRF8 and MYC transcriptional programs. The MEF2D-CEBPE axis is highlighted as a key transcriptional mechanism controlling the block of leukemic cell self-renewal and differentiation in AML. This chapter starts with the structure and function of MEF2 family proteins, specifically summarizing and analyzing the role of MEF2D in B-ALL and AML, mediating the complex molecular mechanisms of transcriptional regulation and exploring their implications for human health and disease.
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Affiliation(s)
- Pengcheng Zhang
- Department of Medicine, Division of Hematology/Oncology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA
- O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA
| | - Rui Lu
- Department of Medicine, Division of Hematology/Oncology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA.
- O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA.
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4
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Liu B, Ou WC, Fang L, Tian CW, Xiong Y. Myocyte Enhancer Factor 2A Plays a Central Role in the Regulatory Networks of Cellular Physiopathology. Aging Dis 2022; 14:331-349. [PMID: 37008050 PMCID: PMC10017154 DOI: 10.14336/ad.2022.0825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/25/2022] [Indexed: 11/18/2022] Open
Abstract
Cell regulatory networks are the determinants of cellular homeostasis. Any alteration to these networks results in the disturbance of cellular homeostasis and induces cells towards different fates. Myocyte enhancer factor 2A (MEF2A) is one of four members of the MEF2 family of transcription factors (MEF2A-D). MEF2A is highly expressed in all tissues and is involved in many cell regulatory networks including growth, differentiation, survival and death. It is also necessary for heart development, myogenesis, neuronal development and differentiation. In addition, many other important functions of MEF2A have been reported. Recent studies have shown that MEF2A can regulate different, and sometimes even mutually exclusive cellular events. How MEF2A regulates opposing cellular life processes is an interesting topic and worthy of further exploration. Here, we reviewed almost all MEF2A research papers published in English and summarized them into three main sections: 1) the association of genetic variants in MEF2A with cardiovascular disease, 2) the physiopathological functions of MEF2A, and 3) the regulation of MEF2A activity and its regulatory targets. In summary, multiple regulatory patterns for MEF2A activity and a variety of co-factors cause its transcriptional activity to switch to different target genes, thereby regulating opposing cell life processes. The association of MEF2A with numerous signaling molecules establishes a central role for MEF2A in the regulatory network of cellular physiopathology.
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Affiliation(s)
- Benrong Liu
- Department of Cardiology, Guangzhou Institute of Cardiovascular Disease, Guangdong Key Laboratory of Vascular Diseases, State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.
- Correspondence should be addressed to: Dr. Benrong Liu, the Second Affiliated Hospital, Guangzhou Medical University, Guangdong, China. E-mail: ; or Yujuan Xiong, Panyu Hospital of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangdong, China. .
| | - Wen-Chao Ou
- Department of Cardiology, Guangzhou Institute of Cardiovascular Disease, Guangdong Key Laboratory of Vascular Diseases, State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.
| | - Lei Fang
- Department of Cardiology, Guangzhou Institute of Cardiovascular Disease, Guangdong Key Laboratory of Vascular Diseases, State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.
| | - Chao-Wei Tian
- General Practice, the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.
| | - Yujuan Xiong
- Department of Laboratory Medicine, Panyu Hospital of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China.
- Correspondence should be addressed to: Dr. Benrong Liu, the Second Affiliated Hospital, Guangzhou Medical University, Guangdong, China. E-mail: ; or Yujuan Xiong, Panyu Hospital of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangdong, China. .
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5
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Chaudhary R, Agarwal V, Kaushik AS, Rehman M. Involvement of myocyte enhancer factor 2c in the pathogenesis of autism spectrum disorder. Heliyon 2021; 7:e06854. [PMID: 33981903 PMCID: PMC8082549 DOI: 10.1016/j.heliyon.2021.e06854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/09/2020] [Accepted: 04/15/2021] [Indexed: 12/29/2022] Open
Abstract
Myocyte enhancer factor 2 (MEF2), a family of transcription factor of MADS (minichromosome maintenance 1, agamous, deficiens and serum response factor)-box family needed in the growth and differentiation of a variety of human cells, such as neural, immune, endothelial, and muscles. As per existing literature, MEF2 transcription factors have also been associated with synaptic plasticity, the developmental mechanisms governing memory and learning, and several neurologic conditions, like autism spectrum disorders (ASDs). Recent genomic findings have ascertained a link between MEF2 defects, particularly in the MEF2C isoform and the ASD. In this review, we summarized a concise overview of the general regulation, structure and functional roles of the MEF2C transcription factor. We further outlined the potential role of MEF2C as a risk factor for various neurodevelopmental disorders, such as ASD, MEF2C Haploinsufficiency Syndrome and Fragile X syndrome.
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Affiliation(s)
- Rishabh Chaudhary
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Vipul Agarwal
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Arjun Singh Kaushik
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Mujeeba Rehman
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
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6
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Main P, Tan WJ, Wheeler D, Fitzsimons HL. Increased Abundance of Nuclear HDAC4 Impairs Neuronal Development and Long-Term Memory. Front Mol Neurosci 2021; 14:616642. [PMID: 33859551 PMCID: PMC8042284 DOI: 10.3389/fnmol.2021.616642] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 03/09/2021] [Indexed: 12/02/2022] Open
Abstract
Dysregulation of the histone deacetylase HDAC4 is associated with both neurodevelopmental and neurodegenerative disorders, and a feature common to many of these disorders is impaired cognitive function. HDAC4 shuttles between the nucleus and cytoplasm in both vertebrates and invertebrates and alterations in the amounts of nuclear and/or cytoplasmic HDAC4 have been implicated in these diseases. In Drosophila, HDAC4 also plays a critical role in the regulation of memory, however, the mechanisms through which it acts are unknown. Nuclear and cytoplasmically-restricted HDAC4 mutants were expressed in the Drosophila brain to investigate a mechanistic link between HDAC4 subcellular distribution, transcriptional changes and neuronal dysfunction. Deficits in mushroom body morphogenesis, eye development and long-term memory correlated with increased abundance of nuclear HDAC4 but were associated with minimal transcriptional changes. Although HDAC4 sequesters MEF2 into punctate foci within neuronal nuclei, no alteration in MEF2 activity was observed on overexpression of HDAC4, and knockdown of MEF2 had no impact on long-term memory, indicating that HDAC4 is likely not acting through MEF2. In support of this, mutation of the MEF2 binding site within HDAC4 also had no impact on nuclear HDAC4-induced impairments in long-term memory or eye development. In contrast, the defects in mushroom body morphogenesis were ameliorated by mutation of the MEF2 binding site, as well as by co-expression of MEF2 RNAi, thus nuclear HDAC4 acts through MEF2 to disrupt mushroom body development. These data provide insight into the mechanisms through which dysregulation of HDAC4 subcellular distribution impairs neurological function and provides new avenues for further investigation.
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Affiliation(s)
- Patrick Main
- Biochemistry, Biotechnology and Biomedical Science Group, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Wei Jun Tan
- Biochemistry, Biotechnology and Biomedical Science Group, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - David Wheeler
- NSW Department of Primary Industries, Orange, NSW, Australia
| | - Helen L. Fitzsimons
- Biochemistry, Biotechnology and Biomedical Science Group, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
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Metastatic Phosphatase PRL-3 Induces Ovarian Cancer Stem Cell Sub-population through Phosphatase-Independent Deacetylation Modulations. iScience 2019; 23:100766. [PMID: 31887658 PMCID: PMC6941878 DOI: 10.1016/j.isci.2019.100766] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/01/2019] [Accepted: 12/09/2019] [Indexed: 12/18/2022] Open
Abstract
Cancer stem cells (CSCs) are responsible for tumor initiation, chemoresistance, metastasis, and relapse, but the underlying molecular origin of CSCs remains elusive. Here we identified that metastatic phosphatase of regenerating liver 3 (PRL-3) transcriptionally upregulates SOX2 in the expansion of CSC sub-population from normal cancer cells. Mechanistically, SOX2 upregulation is attributed to the binding of the acetylated myocyte enhancer factor 2A (MEF2A) to SOX2 promoter in tumor cells. In parallel, PRL-3 competitively binds to Class IIa histone deacetylase 4 (HDAC4) to facilitate HDAC4 translocation, leading to the disassociation of HDAC4 from MEF2A and histones. The released MEF2A and histones thus remain acetylated and render the subsequent accessibility of the acetylated MEF2A to SOX2 promoter region. Clinical relevance among PRL-3, SOX2, and HDAC4 is validated in ovary cancer samples. Therefore, this PRL-3-HDAC4-MEF2A/histones-SOX2 signaling axis would be a potential therapeutic target in inhibiting ovarian cancer metastasis and relapse. PRL-3 promotes the expansion of CSC-like cells via transcriptional SOX2 upregulation Binding of MEF2A to SOX2 promoter bridges the PRL-3-induced SOX2 upregulation PRL-3 competitively binds HDAC4 to cause the disassociation of HDAC4 from MEF2A Acetylated histones render the accessibility of SOX2 promoter region to MEF2A
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8
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Huang B, Wang J, Zhang X, Xie Z, Wu H, Liu J, Jie Z, Zhao X, Qin A, Fan S, Chen J, Zhao F. Administration of SB239063 Ameliorates Ovariectomy-Induced Bone Loss via Suppressing Osteoclastogenesis in Mice. Front Pharmacol 2019; 10:900. [PMID: 31474861 PMCID: PMC6704231 DOI: 10.3389/fphar.2019.00900] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/17/2019] [Indexed: 11/13/2022] Open
Abstract
Activation of osteoclast formation and function is crucial for the development of osteolytic diseases such as osteoporosis. RANKL (receptor activator of nuclear factor-κB ligand) activates NF-κB (nuclear factor κB), MAPK (mitogen-activated protein kinase), and NFATc1 (nuclear factor of activated T-cells, cytoplasmic 1) signaling pathways to induce osteoclastogenesis. In this study, we demonstrated that SB239063, a p38-specific inhibitor, suppressed osteoclastogenesis and bone resorption via inhibiting phosphorylation of MEF2C (myocyte enhancer factor 2C) and subsequently leading to MEF2C degradation by ubiquitination. Knockdown of MEF2C impaired osteoclast formation due to decreased c-Fos expression. Furthermore, MEF2C can directly bind to the promoter region of c-Fos to initiate its transcription. Interestingly, overexpression of either MEF2C or c-Fos can partially rescue the inhibitory effect of SB239063 on osteoclastogenesis. In addition, in vivo data proved that SB239063 also played a preventive role in both LPS (lipopolysaccharide)- and OVX (ovariectomy)-induced bone loss in mice. In conclusion, our results show that SB239063 can be a potential therapy for osteolytic diseases, and a novel p38/MEF2C/c-Fos axis is essential for osteoclastogenesis.
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Affiliation(s)
- Bao Huang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Jiasheng Wang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Xuyang Zhang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Ziang Xie
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Hao Wu
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Junhui Liu
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Zhiwei Jie
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Xiangde Zhao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - An Qin
- Department of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shunwu Fan
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Jian Chen
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
| | - Fengdong Zhao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, China
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9
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MEF-2 isoforms' (A-D) roles in development and tumorigenesis. Oncotarget 2019; 10:2755-2787. [PMID: 31105874 PMCID: PMC6505634 DOI: 10.18632/oncotarget.26763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 02/01/2019] [Indexed: 12/29/2022] Open
Abstract
Myocyte enhancer factor (MEF)-2 plays a critical role in proliferation, differentiation, and development of various cell types in a tissue specific manner. Four isoforms of MEF-2 (A-D) differentially participate in controlling the cell fate during the developmental phases of cardiac, muscle, vascular, immune and skeletal systems. Through their associations with various cellular factors MEF-2 isoforms can trigger alterations in complex protein networks and modulate various stages of cellular differentiation, proliferation, survival and apoptosis. The role of the MEF-2 family of transcription factors in the development has been investigated in various cell types, and the evolving alterations in this family of transcription factors have resulted in a diverse and wide spectrum of disease phenotypes, ranging from cancer to infection. This review provides a comprehensive account on MEF-2 isoforms (A-D) from their respective localization, signaling, role in development and tumorigenesis as well as their association with histone deacetylases (HDACs), which can be exploited for therapeutic intervention.
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10
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Crittenden JR, Skoulakis EMC, Goldstein ES, Davis RL. Drosophila mef2 is essential for normal mushroom body and wing development. Biol Open 2018; 7:bio.035618. [PMID: 30115617 PMCID: PMC6176937 DOI: 10.1242/bio.035618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
MEF2 (myocyte enhancer factor 2) transcription factors are found in the brain and muscle of insects and vertebrates and are essential for the differentiation of multiple cell types. We show that in the fruit fly Drosophila, MEF2 is essential for the formation of mushroom bodies in the embryonic brain and for the normal development of wings in the adult. In embryos mutant for mef2, there is a striking reduction in the number of mushroom body neurons and their axon bundles are not detectable. The onset of MEF2 expression in neurons of the mushroom bodies coincides with their formation in the embryo and, in larvae, expression is restricted to post-mitotic neurons. In flies with a mef2 point mutation that disrupts nuclear localization, we find that MEF2 is restricted to a subset of Kenyon cells that project to the α/β, and γ axonal lobes of the mushroom bodies, but not to those forming the α’/β’ lobes. Summary:Drosophila mef2 expression is restricted to subsets of mushroom body neurons, from the time of their differentiation to adulthood, and is essential for mushroom body formation.
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Affiliation(s)
- Jill R Crittenden
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Efthimios M C Skoulakis
- Division of Neuroscience, Biomedical Sciences Research Centre 'Alexander Fleming', Vari, 16672, Greece
| | - Elliott S Goldstein
- School of Life Science, Cellular, Molecular and Bioscience Program, Arizona State University, Tempe, AZ, 85287, USA
| | - Ronald L Davis
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
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11
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Ghosh TK, Aparicio-Sánchez JJ, Buxton S, Ketley A, Mohamed T, Rutland CS, Loughna S, Brook JD. Acetylation of TBX5 by KAT2B and KAT2A regulates heart and limb development. J Mol Cell Cardiol 2017; 114:185-198. [PMID: 29174768 DOI: 10.1016/j.yjmcc.2017.11.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 11/17/2017] [Accepted: 11/17/2017] [Indexed: 11/28/2022]
Abstract
TBX5 plays a critical role in heart and forelimb development. Mutations in TBX5 cause Holt-Oram syndrome, an autosomal dominant condition that affects the formation of the heart and upper-limb. Several studies have provided significant insight into the role of TBX5 in cardiogenesis; however, how TBX5 activity is regulated by other factors is still unknown. Here we report that histone acetyltransferases KAT2A and KAT2B associate with TBX5 and acetylate it at Lys339. Acetylation potentiates its transcriptional activity and is required for nuclear retention. Morpholino-mediated knockdown of kat2a and kat2b transcripts in zebrafish severely perturb heart and limb development, mirroring the tbx5a knockdown phenotype. The phenotypes found in MO-injected embryos were also observed when we introduced mutations in the kat2a or kat2b genes using the CRISPR-Cas system. These studies highlight the importance of KAT2A and KAT2B modulation of TBX5 and their impact on heart and limb development.
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Affiliation(s)
- Tushar K Ghosh
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - José J Aparicio-Sánchez
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Sarah Buxton
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Ami Ketley
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Tasabeeh Mohamed
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Catrin S Rutland
- The School of Veterinary Medicine and Science, Sutton Bonington Campus, Sutton Bonington, University of Nottingham, LE12 5RD, UK
| | - Siobhan Loughna
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - J David Brook
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
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12
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Hoyeck MP, Hadj-Moussa H, Storey KB. The role of MEF2 transcription factors in dehydration and anoxia survival in Rana sylvatica skeletal muscle. PeerJ 2017; 5:e4014. [PMID: 29134152 PMCID: PMC5682099 DOI: 10.7717/peerj.4014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/19/2017] [Indexed: 11/20/2022] Open
Abstract
The wood frog (Rana sylvatica) can endure freezing of up to 65% of total body water during winter. When frozen, wood frogs enter a dormant state characterized by a cessation of vital functions (i.e., no heartbeat, blood circulation, breathing, brain activity, or movement). Wood frogs utilize various behavioural and biochemical adaptations to survive extreme freezing and component anoxia and dehydration stresses, including a global suppression of metabolic functions and gene expression. The stress-responsive myocyte enhancer factor-2 (MEF2) transcription factor family regulates the selective expression of genes involved in glucose transport, protein quality control, and phosphagen homeostasis. This study examined the role of MEF2A and MEF2C proteins as well as select downstream targets (glucose transporter-4, calreticulin, and muscle and brain creatine kinase isozymes) in 40% dehydration and 24 h anoxia exposure at the transcriptional, translational, and post-translational levels using qRT-PCR, immunoblotting, and subcellular localization. Mef2a/c transcript levels remained constant during dehydration and anoxia. Total, cytoplasmic, and nuclear MEF2A/C and phospho-MEF2A/C protein levels remained constant during dehydration, whereas a decrease in total MEF2C levels was observed during rehydration. Total and phospho-MEF2A levels remained constant during anoxia, whereas total MEF2C levels decreased during 24 h anoxia and P-MEF2C levels increased during 4 h anoxia. In contrast, cytoplasmic MEF2A levels and nuclear phospho-MEF2A/C levels were upregulated during anoxia. MEF2 downstream targets remained constant during dehydration and anoxia, with the exception of glut4 which was upregulated during anoxia. These results suggest that the upregulated MEF2 response reported in wood frogs during freezing may in part stem from their cellular responses to surviving prolonged anoxia, rather than dehydration, leading to an increase in GLUT4 expression which may have an important role during anoxia survival.
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Affiliation(s)
- Myriam P Hoyeck
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Canada
| | - Hanane Hadj-Moussa
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Canada
| | - Kenneth B Storey
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Canada
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13
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Dong C, Yang XZ, Zhang CY, Liu YY, Zhou RB, Cheng QD, Yan EK, Yin DC. Myocyte enhancer factor 2C and its directly-interacting proteins: A review. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 126:22-30. [DOI: 10.1016/j.pbiomolbio.2017.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/24/2016] [Accepted: 02/01/2017] [Indexed: 11/27/2022]
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14
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Baruffaldi F, Montarras D, Basile V, De Feo L, Badodi S, Ganassi M, Battini R, Nicoletti C, Imbriano C, Musarò A, Molinari S. Dynamic Phosphorylation of the Myocyte Enhancer Factor 2Cα1 Splice Variant Promotes Skeletal Muscle Regeneration and Hypertrophy. Stem Cells 2016; 35:725-738. [PMID: 27612437 DOI: 10.1002/stem.2495] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 07/18/2016] [Accepted: 08/21/2016] [Indexed: 12/20/2022]
Abstract
The transcription factor MEF2C (Myocyte Enhancer Factor 2C) plays an established role in the early steps of myogenic differentiation. However, the involvement of MEF2C in adult myogenesis and in muscle regeneration has not yet been systematically investigated. Alternative splicing of mammalian MEF2C transcripts gives rise to two mutually exclusive protein variants: MEF2Cα2 which exerts a positive control of myogenic differentiation, and MEF2Cα1, in which the α1 domain acts as trans-repressor of the MEF2C pro-differentiation activity itself. However, MEF2Cα1 variants are persistently expressed in differentiating cultured myocytes, suggesting a role in adult myogenesis. We found that overexpression of both MEF2Cα1/α2 proteins in a mouse model of muscle injury promotes muscle regeneration and hypertrophy, with each isoform promoting different stages of myogenesis. Besides the ability of MEF2Cα2 to increase differentiation, we found that overexpressed MEF2Cα1 enhances both proliferation and differentiation of primary myoblasts, and activates the AKT/mTOR/S6K anabolic signaling pathway in newly formed myofibers. The multiple activities of MEF2Cα1 are modulated by phosphorylation of Ser98 and Ser110, two amino acid residues located in the α1 domain of MEF2Cα1. These specific phosphorylations allow the interaction of MEF2Cα1 with the peptidyl-prolyl isomerase PIN1, a regulator of MEF2C functions. Overall, in this study we established a novel regulatory mechanism in which the expression and the phosphorylation of MEF2Cα1 are critically required to sustain the adult myogenesis. The described molecular mechanism will represent a new potential target for the development of therapeutical strategies to treat muscle-wasting diseases. Stem Cells 2017;35:725-738.
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Affiliation(s)
- Fiorenza Baruffaldi
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Didier Montarras
- Département de Biologie du Développement et Cellules Souches, Institut Pasteur (CNRS URA 2578), Paris, France
| | - Valentina Basile
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Luca De Feo
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Sara Badodi
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Massimo Ganassi
- Randall Division of Cell and Molecular Biophysics, King's College London, UK
| | - Renata Battini
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Carmine Nicoletti
- Institute Pasteur-Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University, Rome, Italy.,Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Carol Imbriano
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Antonio Musarò
- Institute Pasteur-Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University, Rome, Italy.,Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Susanna Molinari
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
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15
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Faustino RS, Behfar A, Groenendyk J, Wyles SP, Niederlander N, Reyes S, Puceat M, Michalak M, Terzic A, Perez-Terzic C. Calreticulin secures calcium-dependent nuclear pore competency required for cardiogenesis. J Mol Cell Cardiol 2016; 92:63-74. [PMID: 26826378 DOI: 10.1016/j.yjmcc.2016.01.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 01/20/2016] [Accepted: 01/26/2016] [Indexed: 12/24/2022]
Abstract
Calreticulin deficiency causes myocardial developmental defects that culminate in an embryonic lethal phenotype. Recent studies have linked loss of this calcium binding chaperone to failure in myofibrillogenesis through an as yet undefined mechanism. The purpose of the present study was to identify cellular processes corrupted by calreticulin deficiency that precipitate dysregulation of cardiac myofibrillogenesis related to acquisition of cardiac phenotype. In an embryonic stem cell knockout model, calreticulin deficit (crt(-/-)) compromised nucleocytoplasmic transport of nuclear localization signal-dependent and independent pathways, disrupting nuclear import of the cardiac transcription factor MEF2C. The expression of nucleoporins and associated nuclear transport proteins in derived crt(-/-) cardiomyocytes revealed an abnormal nuclear pore complex (NPC) configuration. Altered protein content in crt(-/-) cells resulted in remodeled NPC architecture that caused decreased pore diameter and diminished probability of central channel occupancy versus wild type counterparts. Ionophore treatment of impaired calcium handling in crt(-/-) cells corrected nuclear pore microarchitecture and rescued nuclear import resulting in normalized myofibrillogenesis. Thus, calreticulin deficiency alters nuclear pore function and structure, impeding myofibrillogenesis in nascent cardiomyocytes through a calcium dependent mechanism. This essential role of calreticulin in nucleocytoplasmic communication competency ties its regulatory action with proficiency of cardiac myofibrillogenesis essential for proper cardiac development.
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Affiliation(s)
- Randolph S Faustino
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
| | - Atta Behfar
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
| | - Jody Groenendyk
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Saranya P Wyles
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
| | - Nicolas Niederlander
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
| | - Santiago Reyes
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
| | | | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Andre Terzic
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
| | - Carmen Perez-Terzic
- Center for Regenerative Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA; Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA; Rehabilitation Research Center, Rochester, MN, USA.
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16
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Guise AJ, Cristea IM. Approaches for Studying the Subcellular Localization, Interactions, and Regulation of Histone Deacetylase 5 (HDAC5). Methods Mol Biol 2016; 1436:47-84. [PMID: 27246208 PMCID: PMC5644287 DOI: 10.1007/978-1-4939-3667-0_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
As a member of the class IIa family of histone deacetylases, the histone deacetylase 5 (HDAC5) is known to undergo nuclear-cytoplasmic shuttling and to be a critical transcriptional regulator. Its misregulation has been linked to prominent human diseases, including cardiac diseases and tumorigenesis. In this chapter, we describe several experimental methods that have proven effective for studying the functions and regulatory features of HDAC5. We present methods for assessing the subcellular localization, protein interactions, posttranslational modifications (PTMs), and activity of HDAC5 from the standpoint of investigating either the endogenous protein or tagged protein forms in human cells. Specifically, given that at the heart of HDAC5 regulation lie its dynamic localization, interactions, and PTMs, we present methods for assessing HDAC5 localization in fixed and live cells, for isolating HDAC5-containing protein complexes to identify its interactions and modifications, and for determining how these PTMs map to predicted HDAC5 structural motifs. Lastly, we provide examples of approaches for studying HDAC5 functions with a focus on its regulation during cell-cycle progression. These methods can readily be adapted for the study of other HDACs or non-HDAC-proteins of interest. Individually, these techniques capture temporal and spatial snapshots of HDAC5 functions; yet together, these approaches provide powerful tools for investigating both the regulation and regulatory roles of HDAC5 in different cell contexts relevant to health and disease.
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Affiliation(s)
- Amanda J Guise
- Department of Molecular Biology, Princeton University, 210 Lewis Thomas Laboratory, Princeton, NJ, 08544, USA
| | - Ileana M Cristea
- Department of Molecular Biology, Princeton University, 210 Lewis Thomas Laboratory, Princeton, NJ, 08544, USA.
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17
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Bai XL, Zhang Q, Ye LY, Liang F, Sun X, Chen Y, Hu QD, Fu QH, Su W, Chen Z, Zhuang ZP, Liang TB. Myocyte enhancer factor 2C regulation of hepatocellular carcinoma via vascular endothelial growth factor and Wnt/β-catenin signaling. Oncogene 2014; 34:4089-97. [PMID: 25328135 DOI: 10.1038/onc.2014.337] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 08/15/2014] [Accepted: 08/29/2014] [Indexed: 01/11/2023]
Abstract
Hepatocellular carcinoma (HCC) is one of the leading malignancies worldwide. Myocyte enhancer factor 2C (MEF2C) was traditionally regarded as a development-associated factor and was recently reported to be an oncogene candidate. We have previously reported overexpression of MEF2C in HCC; however, the roles of MEF2C in HCC remain to be clarified. In this study, HCC cell lines and a xenograft mouse model were used to determine the functions of MEF2C in vitro and in vivo, respectively. Specific plasmids and small interfering RNA were used to upregulate and downregulate MEF2C expression, respectively. Functional assays were performed to assess the influence of MEF2C on cell proliferation, and VEGF-induced vasculogenic mimicry, migration/invasion as well as angiogenesis. Co-immunoprecipitation was conducted to identify the interaction of MEF2C and β-catenin. Human HCC tissue microarrays were used to investigate correlations among MEF2C, β-catenin and involved biomarkers. MEF2C was found to mediate VEGF-induced vasculogenic mimicry, angiogenesis and migration/invasion, with involvement of the p38 MAPK and PKC signaling pathways. However, MEF2C itself inhibited tumor growth in vitro and in vivo. MEF2C was upregulated by and directly interacted with β-catenin. The nuclear translocation of β-catenin blocked by MEF2C was responsible for MEF2C-mediated growth inhibition. The nuclear translocation of MEF2C was associated with intracellular calcium signaling induced by β-catenin. HCC microarrays showed correlations of nuclear MEF2C with the angiogenesis-associated biomarker, CD31, and cytosolic MEF2C with the proliferation-associated biomarker, Ki-67. MEF2C showed double-edged activities in HCC, namely mediating VEGF-induced malignancy enhancement while inhibiting cancer proliferation via blockade of Wnt/β-catenin signaling. The overall effect of MEF2C in HCC progression regulation was dictated by its subcellular distribution. This should be determined prior to any MEF2C-associated intervention in HCC.
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Affiliation(s)
- X L Bai
- 1] Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China [2] Key Laboratory of Cancer Prevention and Intervention, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Q Zhang
- 1] Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China [2] Key Laboratory of Cancer Prevention and Intervention, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - L Y Ye
- 1] Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China [2] Key Laboratory of Cancer Prevention and Intervention, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - F Liang
- Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - X Sun
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Y Chen
- Department of General Surgery, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Q D Hu
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Q H Fu
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - W Su
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Z Chen
- Zhejiang Key Laboratory of Gastro-Intestinal Pathophysiology, Zhejiang Hospital of Traditional Chinese Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Z P Zhuang
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - T B Liang
- 1] Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China [2] Key Laboratory of Cancer Prevention and Intervention, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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18
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Ganassi M, Badodi S, Polacchini A, Baruffaldi F, Battini R, Hughes SM, Hinits Y, Molinari S. Distinct functions of alternatively spliced isoforms encoded by zebrafish mef2ca and mef2cb. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:559-70. [PMID: 24844180 PMCID: PMC4064114 DOI: 10.1016/j.bbagrm.2014.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 04/29/2014] [Accepted: 05/12/2014] [Indexed: 01/06/2023]
Abstract
In mammals, an array of MEF2C proteins is generated by alternative splicing (AS), yet specific functions have not been ascribed to each isoform. Teleost fish possess two MEF2C paralogues, mef2ca and mef2cb. In zebrafish, the Mef2cs function to promote cardiomyogenic differentiation and myofibrillogenesis in nascent skeletal myofibers. We found that zebrafish mef2ca and mef2cb are alternatively spliced in the coding exons 4–6 region and these splice variants differ in their biological activity. Of the two, mef2ca is more abundantly expressed in developing skeletal muscle, its activity is tuned through zebrafish development by AS. By 24 hpf, we found the prevalent expression of the highly active full length protein in differentiated muscle in the somites. The splicing isoform of mef2ca that lacks exon 5 (mef2ca 4–6), encodes a protein that has 50% lower transcriptional activity, and is found mainly earlier in development, before muscle differentiation. mef2ca transcripts including exon 5 (mef2ca 4–5–6) are present early in the embryo. Over-expression of this isoform alters the expression of genes involved in early dorso-ventral patterning of the embryo such as chordin, nodal related 1 and goosecoid, and induces severe developmental defects. AS of mef2cb generates a long splicing isoform in the exon 5 region (Mef2cbL) that predominates during somitogenesis. Mef2cbL contains an evolutionarily conserved domain derived from exonization of a fragment of intron 5, which confers the ability to induce ectopic muscle in mesoderm upon over-expression of the protein. Taken together, the data show that AS is a significant regulator of Mef2c activity. mef2ca and mef2cb gene products are alternatively spliced in zebrafish. Inclusion of exon 5 in mef2ca transcripts is regulated during zebrafish development. Exon 5 confers on Mef2ca the ability to activate early patterning genes. Mef2cb includes an extra octapeptide encoded by a region of intron 5. Inclusion of the extra-octapeptide confers on Mef2cb pro-myogenic activity.
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Affiliation(s)
- M Ganassi
- University of Modena and Reggio Emilia, Department of Life Sciences, Italy; Randall Division of Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, SE1 1UL, UK
| | - S Badodi
- University of Modena and Reggio Emilia, Department of Life Sciences, Italy
| | - A Polacchini
- University of Modena and Reggio Emilia, Department of Life Sciences, Italy
| | - F Baruffaldi
- University of Modena and Reggio Emilia, Department of Life Sciences, Italy
| | - R Battini
- University of Modena and Reggio Emilia, Department of Life Sciences, Italy
| | - S M Hughes
- Randall Division of Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, SE1 1UL, UK
| | - Y Hinits
- Randall Division of Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, SE1 1UL, UK.
| | - S Molinari
- University of Modena and Reggio Emilia, Department of Life Sciences, Italy.
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19
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Fitzsimons HL, Schwartz S, Given FM, Scott MJ. The histone deacetylase HDAC4 regulates long-term memory in Drosophila. PLoS One 2013; 8:e83903. [PMID: 24349558 PMCID: PMC3857321 DOI: 10.1371/journal.pone.0083903] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 11/09/2013] [Indexed: 12/22/2022] Open
Abstract
A growing body of research indicates that pharmacological inhibition of histone deacetylases (HDACs) correlates with enhancement of long-term memory and current research is concentrated on determining the roles that individual HDACs play in cognitive function. Here, we investigate the role of HDAC4 in long-term memory formation in Drosophila. We show that overexpression of HDAC4 in the adult mushroom body, an important structure for memory formation, resulted in a specific impairment in long-term courtship memory, but had no affect on short-term memory. Overexpression of an HDAC4 catalytic mutant also abolished LTM, suggesting a mode of action independent of catalytic activity. We found that overexpression of HDAC4 resulted in a redistribution of the transcription factor MEF2 from a relatively uniform distribution through the nucleus into punctate nuclear bodies, where it colocalized with HDAC4. As MEF2 has also been implicated in regulation of long-term memory, these data suggest that the repressive effects of HDAC4 on long-term memory may be through interaction with MEF2. In the same genetic background, we also found that RNAi-mediated knockdown of HDAC4 impairs long-term memory, therefore we demonstrate that HDAC4 is not only a repressor of long-term memory, but also modulates normal memory formation.
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Affiliation(s)
- Helen L. Fitzsimons
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
- * E-mail:
| | - Silvia Schwartz
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Fiona M. Given
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Maxwell J. Scott
- Department of Entomology, North Carolina State University, Raleigh, North Carolina, United States of America
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20
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Walkinshaw DR, Weist R, Xiao L, Yan K, Kim GW, Yang XJ. Dephosphorylation at a conserved SP motif governs cAMP sensitivity and nuclear localization of class IIa histone deacetylases. J Biol Chem 2013; 288:5591-605. [PMID: 23297420 DOI: 10.1074/jbc.m112.445668] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Histone deacetylase 4 (HDAC4) and its paralogs, HDAC5, -7, and -9 (all members of class IIa), possess multiple phosphorylation sites crucial for 14-3-3 binding and subsequent nuclear export. cAMP signaling stimulates nuclear import of HDAC4 and HDAC5, but the underlying mechanisms remain to be elucidated. Here we show that cAMP potentiates nuclear localization of HDAC9. Mutation of an SP motif conserved in HDAC4, -5, and -9 prevents cAMP-stimulated nuclear localization. Unexpectedly, this treatment inhibits phosphorylation at the SP motif, indicating an inverse relationship between the phosphorylation event and nuclear import. Consistent with this, leptomycin B-induced nuclear import and adrenocorticotropic hormone (ACTH) treatment result in the dephosphorylation at the motif. Moreover, the modification synergizes with phosphorylation at a nearby site, and similar kinetics was observed for both phosphorylation events during myoblast and adipocyte differentiation. These results thus unravel a previously unrecognized mechanism whereby cAMP promotes dephosphorylation and differentially regulates multisite phosphorylation and the nuclear localization of class IIa HDACs.
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Affiliation(s)
- Donald R Walkinshaw
- Rosalind and Morris Goodman Cancer Research Center, McGill University, Montréal, Québec H3A 1A3, Canada
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21
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Clocchiatti A, Florean C, Brancolini C. Class IIa HDACs: from important roles in differentiation to possible implications in tumourigenesis. J Cell Mol Med 2012; 15:1833-46. [PMID: 21435179 PMCID: PMC3918040 DOI: 10.1111/j.1582-4934.2011.01321.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Histone deacetylases (HDACs) are important regulators of gene expression. Specific structural features and distinct regulative mechanisms rationalize the separation of the 18 different human HDACs into four classes. The class II comprises a heterogeneous group of nuclear and cytosolic HDACs involved in the regulation of several cellular functions, not just limited to transcriptional repression. In particular, HDAC4, 5, 7 and 9 belong to the subclass IIa and share many transcriptional partners, including members of the MEF2 family. Genetic studies in mice have disclosed the fundamental contribution of class IIa HDACs to specific developmental/differentiation pathways. In this review, we discuss about the recent literature, which hints a role of class IIa HDACs in the development, growth and aggressiveness of cancer cells.
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Affiliation(s)
- Andrea Clocchiatti
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence Università degli Studi di Udine, Udine, Italy
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22
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Beyond histone and deacetylase: an overview of cytoplasmic histone deacetylases and their nonhistone substrates. J Biomed Biotechnol 2010; 2011:146493. [PMID: 21234400 PMCID: PMC3014693 DOI: 10.1155/2011/146493] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 10/22/2010] [Accepted: 11/16/2010] [Indexed: 01/03/2023] Open
Abstract
Acetylation of lysines is a prominent form of modification in mammalian proteins. Deacetylation of proteins is catalyzed by histone deacetylases, traditionally named after their role in histone deacetylation, transcriptional modulation, and epigenetic regulation. Despite the link between histone deacetylases and chromatin structure, some of the histone deacetylases reside in various compartments in the cytoplasm. Here, we review how these cytoplasmic histone deacetylases are regulated, the identification of nonhistone substrates, and the functional implications of their nondeacetylase enzymatic activities.
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23
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Magli A, Angelelli C, Ganassi M, Baruffaldi F, Matafora V, Battini R, Bachi A, Messina G, Rustighi A, Del Sal G, Ferrari S, Molinari S. Proline isomerase Pin1 represses terminal differentiation and myocyte enhancer factor 2C function in skeletal muscle cells. J Biol Chem 2010; 285:34518-27. [PMID: 20801874 PMCID: PMC2966067 DOI: 10.1074/jbc.m110.104133] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Reversible proline-directed phosphorylation at Ser/Thr-Pro motifs has an essential role in myogenesis, a multistep process strictly regulated by several signaling pathways that impinge on two families of myogenic effectors, the basic helix-loop-helix myogenic transcription factors and the MEF2 (myocyte enhancer factor 2) proteins. The question of how these signals are deciphered by the myogenic effectors remains largely unaddressed. In this study, we show that the peptidyl-prolyl isomerase Pin1, which catalyzes the isomerization of phosphorylated Ser/Thr-Pro peptide bonds to induce conformational changes of its target proteins, acts as an inhibitor of muscle differentiation because its knockdown in myoblasts promotes myotube formation. With the aim of clarifying the mechanism of Pin1 function in skeletal myogenesis, we investigated whether MEF2C, a critical regulator of the myogenic program that is the end point of several signaling pathways, might serve as a/the target for the inhibitory effects of Pin1 on muscle differentiation. We show that Pin1 interacts selectively with phosphorylated MEF2C in skeletal muscle cells, both in vitro and in vivo. The interaction with Pin1 requires two novel critical phospho-Ser/Thr-Pro motifs in MEF2C, Ser98 and Ser110, which are phosphorylated in vivo. Overexpression of Pin1 decreases MEF2C stability and activity and its ability to cooperate with MyoD to activate myogenic conversion. Collectively, these findings reveal a novel role for Pin1 as a regulator of muscle terminal differentiation and suggest that Pin1-mediated repression of MEF2C function could contribute to this function.
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Affiliation(s)
- Alessandro Magli
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41100 Modena, Italy
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Feng L, Song YF, Guan QB, Liu HJ, Ban B, Dong HX, Hou XL, Lee KO, Gao L, Zhao JJ. Long-term ethanol exposure inhibits glucose transporter 4 expression via an AMPK-dependent pathway in adipocytes. Acta Pharmacol Sin 2010; 31:329-40. [PMID: 20173759 DOI: 10.1038/aps.2010.11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
AIM The roles of AMP-activated protein kinase (AMPK) and myocyte enhancer factor 2 isoforms (MEF2A, D) as mediators of the effects of ethanol on glucose transporter 4 (GLUT4) expression are unclear. We studied the effects of ethanol in adipocytes in vivo and in vitro. METHODS Thirty-six male Wistar rats were divided into three groups and given ethanol in a single daily dose of 0, 0.5, or 5 g/kg for 22 weeks. The expression of AMPK, MEF2 isoforms A and D, and GLUT4 was measured and compared in the three groups. The existence of the AMPK/MEF2/GLUT4 pathway in adipocytes and the effects of ethanol on this pathway were studied in (a) epididymal adipose tissue from six male Wistar rats subcutaneously injected with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR, an AMPK activator) or with 0.9% NaCl (control); and (b) isolated rat and human adipocytes treated with or without ethanol, AICAR, and compound C (a selective AMPK inhibitor). Expression of AMPK, MEF2, and GLUT4 was measured by RT-PCR and Western blotting. RESULTS (1) Long-term ethanol exposure decreased activated AMPK, MEF2A, MEF2D, and GLUT4 expression in rat adipose tissue. (2) In rat and human adipocytes, AICAR-induced AMPK activation, with subsequent elevation of MEF2 and GLUT4 expression, was inhibited by compound C. (3) In vitro ethanol-treatment suppressed the AMPK/MEF2/GLUT4 pathway. CONCLUSION The AMPK/MEF2/GLUT4 pathway exists in both rat and human adipocytes, and activated AMPK may positively regulate MEF2 and GLUT4 expression. Ethanol inhibition of this pathway leads to decreased GLUT4 expression, thus reducing insulin sensitivity and glucose tolerance.
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Guella I, Rimoldi V, Asselta R, Ardissino D, Francolini M, Martinelli N, Girelli D, Peyvandi F, Tubaro M, Merlini PA, Mannucci PM, Duga S. Association and functional analyses of MEF2A as a susceptibility gene for premature myocardial infarction and coronary artery disease. ACTA ACUST UNITED AC 2009; 2:165-72. [PMID: 20031581 DOI: 10.1161/circgenetics.108.819326] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Mutations in the MEF2A gene, coding for a member of the myocyte enhancer factor 2 family of transcription factors, have been reported in patients with coronary artery disease and myocardial infarction (MI). In particular, a 21-bp deletion and 3 missense mutations were demonstrated either to reduce MEF2A transcriptional activity or to impair its nuclear translocation. However, the association of MEF2A with coronary artery disease/MI was not confirmed in other studies. We analyzed the role of MEF2A in the pathogenesis of MI in 2008 Italian patients with premature MI and in 2008 controls. METHODS AND RESULTS Mutational screening of exon 8 (containing all so-far reported point mutations) disclosed 5 novel and 2 previously described missense mutations. Microsatellite genotyping and sequencing revealed the presence of the 21-bp deletion (located in exon 12) in 5 cases and in none of the controls. Functional studies on mutant proteins showed no alteration, neither in the transactivating properties (all mutants) nor in the nuclear localization (21-bp deletion). Furthermore, an association analysis performed using 3 microsatellites at the MEF2A locus showed no significant association with MI. These results were confirmed in a replication study performed on an independent Italian population with coronary artery disease. CONCLUSIONS All together, our data do not support MEF2A as a susceptibility gene for coronary artery disease/MI in the Italian population.
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Affiliation(s)
- Ilaria Guella
- Department of Biology and Genetics for Medical Sciences, University of Milan, Via Viotti 3/5, Milan, Italy
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Paroni G, Cernotta N, Dello Russo C, Gallinari P, Pallaoro M, Foti C, Talamo F, Orsatti L, Steinkühler C, Brancolini C. PP2A regulates HDAC4 nuclear import. Mol Biol Cell 2008; 19:655-67. [PMID: 18045992 PMCID: PMC2230598 DOI: 10.1091/mbc.e07-06-0623] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 11/12/2007] [Accepted: 11/20/2007] [Indexed: 11/11/2022] Open
Abstract
Different signal-regulated serine/threonine kinases phosphorylate class II histone deacetylases (HDACs) to promote nuclear export, cytosolic accumulation, and activation of gene transcription. However, little is known about mechanisms operating in the opposite direction, which, possibly through phosphatases, should promote class II HDACs nuclear entry and subsequent gene repression. Here we show that HDAC4 forms a complex with the PP2A holoenzyme C alpha, A alpha, B/PR55 alpha. In vitro and in vivo binding studies demonstrate that the N-terminus of HDAC4 interacts with the catalytic subunit of PP2A. HDAC4 is dephosphorylated by PP2A and experiments using okadaic acid or RNA interference have revealed that PP2A controls HDAC4 nuclear import. Moreover, we identified serine 298 as a putative phosphorylation site important for HDAC4 nuclear import. The HDAC4 mutant mimicking phosphorylation of serine 298 is defective in nuclear import. Mutation of serine 298 to alanine partially rescues the defect in HDAC4 nuclear import observed in cells with down-regulated PP2A. These observations suggest that PP2A, via the dephosphorylation of multiple serines including the 14-3-3 binding sites and serine 298, controls HDAC4 nuclear import.
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Affiliation(s)
- Gabriela Paroni
- *Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Biologia and MATI Center of Excellence, Universita' di Udine, 33100 Udine, Italy; and
| | - Nadia Cernotta
- *Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Biologia and MATI Center of Excellence, Universita' di Udine, 33100 Udine, Italy; and
| | | | | | | | - Carmela Foti
- *Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Biologia and MATI Center of Excellence, Universita' di Udine, 33100 Udine, Italy; and
| | - Fabio Talamo
- IRBM/Merck Research Laboratories Rome, 00040 Pomezia, Italy
| | - Laura Orsatti
- IRBM/Merck Research Laboratories Rome, 00040 Pomezia, Italy
| | | | - Claudio Brancolini
- *Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Biologia and MATI Center of Excellence, Universita' di Udine, 33100 Udine, Italy; and
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Gulec S, Ruchan Akar A, Akar N. MEF2A sequence variants in Turkish population. Clin Appl Thromb Hemost 2007; 14:465-7. [PMID: 18160598 DOI: 10.1177/1076029607306403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Myocyte enhancer factor 2 (MEF2) is present in skeletal, cardiac, and smooth muscles and in neurons. MEF2A gene encodes a transcription factor which was on 15q26. The objective was to study the MEF2A gene in patients with premature MI. The control group consisted of 87 subjects who were older than 45 years with no history of cardiovascular disease or MI and no family history of CAD. The premature MI group consisted of 69 patients with documented MI younger than 45 years. No abnormal bands with single strand conformation polymorphism were detected after screening exon 1 through exon 8. This is the first study that detected 145408: T>C polymorphism in intron 10. In both study groups, the rare polymorphism P279L in exon 7, T>C polymorphism in intron 10, and 21-bp deletion in exon 11 of the gene were not found. The data supported the previous studies indicating no association between MEF2A gene and premature MI.
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Affiliation(s)
- Sukru Gulec
- Ankara University Biotechnology Institute, Ankara University School of Medicine, Ankara, Turkey
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28
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Nagel S, Meyer C, Quentmeier H, Kaufmann M, Drexler HG, MacLeod RAF. MEF2C is activated by multiple mechanisms in a subset of T-acute lymphoblastic leukemia cell lines. Leukemia 2007; 22:600-7. [PMID: 18079734 DOI: 10.1038/sj.leu.2405067] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In T-cell acute lymphoblastic leukemia (T-ALL) the cardiac homeobox gene NKX2-5 (at 5q35) is variously deregulated by regulatory elements coordinating with BCL11B (at 14q32.2), or the T-cell receptor gene TRD (at 14q11.2), respectively. NKX2-5 is normally expressed in developing spleen and heart, regulating fundamental processes, including differentiation and survival. In this study we investigated whether NKX2-5 expression in T-ALL cell lines reactivates these embryonal pathways contributing to leukemogenesis. Among 18 known targets analyzed, we identified three genes regulated by NKX2-5 in T-ALL cells, including myocyte enhancer factor 2C (MEF2C). Knockdown and overexpression assays confirmed MEF2C activation by NKX2-5 at both the RNA and protein levels. Direct interactions between NKX2-5 and GATA3 as indicated by co-immunoprecipitation data may contribute to MEF2C regulation. In T-ALL cell lines LOUCY and RPMI-8402 MEF2C expression was correlated with a 5q14 deletion, encompassing noncoding proximal gene regions. Fusion constructs with green fluorescent protein permitted subcellular detection of MEF2C protein in nuclear speckles interpretable as repression complexes. MEF2C consistently inhibits expression of NR4A1/NUR77, which regulates apoptosis via BCL2 transformation. Taken together, our data identify distinct mechanisms underlying ectopic MEF2C expression in T-ALL, either as a downstream target of NKX2-5, or via chromosomal aberrations deleting proximal gene regions.
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Affiliation(s)
- S Nagel
- Human and Animal Cell Cultures, DSMZ, Braunschweig, Germany.
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29
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Abstract
In the last decade, the identification of enzymes that regulate acetylation of histones and nonhistone proteins has revealed the key role of dynamic acetylation and deacetylation in various cellular processes. Mammalian histone deacetylases (HDACs), which catalyse the removal of acetyl groups from lysine residues, are grouped into three classes, on the basis of similarity to yeast counterparts. An abundance of experimental evidence has established class IIa HDACs as crucial transcriptional regulators of various developmental and differentiation processes. In the past 5 years, a tremendous effort has been dedicated to characterizing the regulation of these enzymes. In this review, we summarize the latest discoveries in the field and discuss the molecular and structural determinants of class IIa HDACs regulation. Finally, we emphasize that comprehension of the mechanisms underlying class IIa HDAC functions is essential for potential therapeutic applications.
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Affiliation(s)
- M Martin
- Cellular and Molecular Biology Unit, FUSAGx, Gembloux, Belgium
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30
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Paroni G, Fontanini A, Cernotta N, Foti C, Gupta MP, Yang XJ, Fasino D, Brancolini C. Dephosphorylation and caspase processing generate distinct nuclear pools of histone deacetylase 4. Mol Cell Biol 2007; 27:6718-32. [PMID: 17636017 PMCID: PMC2099224 DOI: 10.1128/mcb.00853-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
From the nucleus, histone deacetylase 4 (HDAC4) regulates a variety of cellular processes, including growth, differentiation, and survival, by orchestrating transcriptional changes. Extracellular signals control its repressive influence mostly through regulating its nuclear-cytoplasmic shuttling. In particular, specific posttranslational modifications such as phosphorylation and caspase-mediated proteolytic processing operate on HDAC4 to promote its nuclear accumulation or export. To understand the signaling properties of this deacetylase, we investigated its cell death-promoting activity and the transcriptional repression potential of different mutants that accumulate in the nucleus. Here we show that, compared to that of other nuclear forms of HDAC4, a caspase-generated nuclear fragment exhibits a stronger cell death-promoting activity coupled with increased repressive effect on Runx2- or SRF-dependent transcription. However, this mutant displays reduced repressive action on MEF2C-driven transcription. Photobleaching experiments and quantitative analysis of the raw data, based on a two-binding-state compartmental model, demonstrate the existence of two nuclear pools of HDAC4 with different chromatin-binding properties. The caspase-generated fragment is weakly bound to chromatin, whereas an HDAC4 mutant defective in 14-3-3 binding or the wild-type HDAC5 protein forms a more stable complex. The tightly bound species show an impaired ability to induce cell death and repress Runx2- or SRF-dependent transcription less efficiently. We propose that, through specific posttranslation modifications, extracellular signals control two distinct nuclear pools of HDAC4 to differentially dictate cell death and differentiation. These two nuclear pools of HDAC4 are characterized by different repression potentials and divergent dynamics of chromatin interaction.
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Affiliation(s)
- Gabriela Paroni
- Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Biologia, and MATI Center of Excellence, Università di Udine, Udine, Italy
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Bai X, Wu L, Liang T, Liu Z, Li J, Li D, Xie H, Yin S, Yu J, Lin Q, Zheng S. Overexpression of myocyte enhancer factor 2 and histone hyperacetylation in hepatocellular carcinoma. J Cancer Res Clin Oncol 2007; 134:83-91. [PMID: 17611778 DOI: 10.1007/s00432-007-0252-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 05/08/2007] [Indexed: 12/23/2022]
Abstract
PURPOSE It has been indicated that activated hepatic stellate cells (HSCs) play key roles on the pathogenesis of hepatocellular carcinoma (HCC). The purpose of the study was to investigate the potential mechanism in it. METHODS Activation of HSCs, the expression of myocyte enhancer factor 2 (MEF2), class II histone deacetylases (II HDACs) and histone acetylation were analyzed in specimens of primary HCCs, cirrhotic and normal livers. Activated HSCs were identified using anti-a-smooth muscle actin (a-SMA) by Immunohistochemistry (IHC). The levels of expression of MEF2A, MEF2C and II HDACs mRNA and protein were measured by real time quantitative PCR and western blot (WB). Histone acetylation was assessed using anti-acetyl-histone H3, -H4 by WB and IHC. A P value < 0.05 was considered statistically significant. RESULTS A-SMA positive activated HSCs were more prominent in HCCs and cirrhotic livers than in normal livers, accompanied by marked expression of MEF2A and MEF2C. The expression of MEF2A, MEF2C and II HDACs, both mRNA and protein, were much more enhanced in HCCs than those in cirrhotic and normal livers (P < 0.05). Histone H3 and H4 were hyperacetylated in HCCs compared with those in cirrhotic and normal livers (P < 0.05). The correlation coefficients between the expression of MEF2 and II HDACs, acetyl-histones were all beyond 0.5. CONCLUSIONS These data showed a potential molecular mechanism that activated HSCs participate in the pathogenesis of HCCs by overexpression of MEF2 and its consequent impact on histone hyperacetylation. Further investigations aimed at interfering MEF2 expression are needed.
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Affiliation(s)
- Xueli Bai
- Key Laboratory of Multi-organ Transplantation of Ministry of Public Health, The First Affiliated Hospital, School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou 310003, People's Republic of China
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32
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Seibel NM, Eljouni J, Nalaskowski MM, Hampe W. Nuclear localization of enhanced green fluorescent protein homomultimers. Anal Biochem 2007; 368:95-9. [PMID: 17586454 DOI: 10.1016/j.ab.2007.05.025] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 04/24/2007] [Accepted: 05/22/2007] [Indexed: 11/30/2022]
Abstract
The green fluorescent protein (GFP) and its variants are used in many studies to determine the subcellular localization of other proteins by analyzing fusion proteins. The main problem for nuclear localization studies is the fact that, to some extent, GFP translocates to the nucleus on its own. Because the nuclear import could be due to unspecific diffusion of the relatively small GFP through the nuclear pores, we analyzed the localization of multimers of a GFP variant, the enhanced GFP (EGFP). By detecting the fluorescence of the expressed proteins in gels after nonreducing SDS-PAGE, we demonstrate the integrity of the expressed proteins. Nevertheless, even EGFP homotetramers and homohexamers are found in the nuclei of the five analyzed mammalian cell lines. The use of fusion constructs of small proteins with multimeric EGFP alone, therefore, is not adequate to prove nuclear import processes. Fusion to tetrameric EGFP in combination with a careful quantification of the fluorescence intensities in the nucleus and cytoplasm might be sufficient in many cases to identify a significant difference between the fusion protein and tetrameric EGFP alone to deduce a nuclear localization signal.
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Affiliation(s)
- Nicole Maria Seibel
- Department of Biochemistry, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
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33
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Perez-Terzic C, Faustino RS, Boorsma BJ, Arrell DK, Niederländer NJ, Behfar A, Terzic A. Stem cells transform into a cardiac phenotype with remodeling of the nuclear transport machinery. ACTA ACUST UNITED AC 2007; 4 Suppl 1:S68-76. [PMID: 17230218 DOI: 10.1038/ncpcardio0763] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Accepted: 11/03/2006] [Indexed: 01/08/2023]
Abstract
Nuclear transport of transcription factors is a critical step in stem cell commitment to a tissue-specific lineage. While it is recognized that nuclear pores are gatekeepers of nucleocytoplasmic exchange, it is unknown how the nuclear transport machinery becomes competent to support genetic reprogramming and cell differentiation. Here, we report the dynamics of nuclear transport factor expression and nuclear pore microanatomy during cardiac differentiation of embryonic stem cells. Cardiac progeny derived from pluripotent stem cells displayed a distinct proteomic profile characterized by the emergence of cardiac-specific proteins. This profile correlated with the nuclear translocation of cardiac transcription factors. The nuclear transport genes, including nucleoporins, importins, exportins, transportins, and Ran-related factors, were globally downregulated at the genomic level, streamlining the differentiation program underlying stem cell-derived cardiogenesis. Establishment of the cardiac molecular phenotype was associated with an increased density of nuclear pores spanning the nuclear envelope. At nanoscale resolution, individual nuclear pores exhibited conformational changes resulting in the expansion of the pore diameter and an augmented probability of conduit occupancy. Thus, embryonic stem cells undergo adaptive remodeling of the nuclear transport infrastructure associated with nuclear translocation of cardiac transcription factors and execution of the cardiogenic program, underscoring the plasticity of the nucleocytoplasmic trafficking machinery in accommodating differentiation requirements.
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Affiliation(s)
- Carmen Perez-Terzic
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Karvonen U, Jänne OA, Palvimo JJ. Androgen receptor regulates nuclear trafficking and nuclear domain residency of corepressor HDAC7 in a ligand-dependent fashion. Exp Cell Res 2006; 312:3165-83. [PMID: 16860317 DOI: 10.1016/j.yexcr.2006.06.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 06/13/2006] [Accepted: 06/14/2006] [Indexed: 10/24/2022]
Abstract
In addition to chromosomal proteins, histone deacetylases (HDACs) target transcription factors in transcriptional repression. Here, we show that the class II HDAC family member HDAC7 is an efficient corepressor of the androgen receptor (AR). HDAC7 resided in the cytoplasm in the absence of AR or a cognate ligand, but hormone-occupancy of AR induced nuclear transfer of HDAC7. Nuclear colocalization pattern of AR and HDAC7 was dependent on the nature of the ligand. In the presence of testosterone, a portion of HDAC7 localized to pearl-like nuclear domains, whereas AR occupied with antagonistic ligands cyproterone acetate- or casodex (bicalutamide) recruited HDAC7 from these domains to colocalize with the receptor in speckles and nucleoplasm in a more complete fashion. Ectopic expression of PML-3 relieved the repressive effect of HDAC7 on AR function by sequestering HDAC7 to PML-3 domains. AR acetylation at Lys630/632/633 was not the target of HDAC7 repression, since repression of AR function was independent of these acetylation sites. Moreover, the deacetylase activity of HDAC7 was in part dispensable in the repression of AR function. In sum, our results identify HDAC7 as a novel AR corepressor whose subcellular and subnuclear compartmentalization can be regulated in an androgen-selective manner.
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Affiliation(s)
- Ulla Karvonen
- Biomedicum Helsinki, Institute of Biomedicine, University of Helsinki, PO Box 63, FI-00014 Helsinki, Finland
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35
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Verger A, Quinlan KGR, Crofts LA, Spanò S, Corda D, Kable EPW, Braet F, Crossley M. Mechanisms directing the nuclear localization of the CtBP family proteins. Mol Cell Biol 2006; 26:4882-94. [PMID: 16782877 PMCID: PMC1489157 DOI: 10.1128/mcb.02402-05] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The C-terminal binding protein (CtBP) family includes four proteins (CtBP1 [CtBP1-L], CtBP3/BARS [CtBP1-S], CtBP2, and RIBEYE) which are implicated both in transcriptional repression and in intracellular trafficking. However, the precise mechanisms by which different CtBP proteins are targeted to different subcellular regions remains unknown. Here, we report that the nuclear import of the various CtBP proteins and splice isoforms is differentially regulated. We show that CtBP2 contains a unique nuclear localization signal (NLS) located within its N-terminal region, which contributes to its nuclear accumulation. Using heterokaryon assays, we show that CtBP2 is capable of shuttling between the nucleus and cytoplasm of the cell. Moreover, CtBP2 can heterodimerize with CtBP1-L and CtBP1-S and direct them to the nucleus. This effect strongly depends on the CtBP2 NLS. PXDLS motif-containing transcription factors, such as BKLF, that bind CtBP proteins can also direct them to the nucleus. We also report the identification of a splice isoform of CtBP2, CtBP2-S, that lacks the N-terminal NLS and localizes to the cytoplasm. Finally, we show that mutation of the CtBP NADH binding site impairs the ability of the proteins to dimerize and to associate with BKLF. This reduces the nuclear accumulation of CtBP1. Our results suggest a model in which the nuclear localization of CtBP proteins is influenced by the CtBP2 NLS, by binding to PXDLS motif partner proteins, and through the effect of NADH on CtBP dimerization.
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Affiliation(s)
- Alexis Verger
- School of Molecular and Microbial Biosciences, Biochemistry Building G08, University of Sydney, Sydney, New South Wales 2006, Australia
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Holmes BF, Sparling DP, Olson AL, Winder WW, Dohm GL. Regulation of muscle GLUT4 enhancer factor and myocyte enhancer factor 2 by AMP-activated protein kinase. Am J Physiol Endocrinol Metab 2005; 289:E1071-6. [PMID: 16105857 DOI: 10.1152/ajpendo.00606.2004] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As the primary glucose transporter in skeletal muscle, GLUT4 is an important factor in the regulation of blood glucose. We previously reported that stimulation of AMP-activated protein kinase (AMPK) with 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) increased GLUT4 expression in muscle. GLUT4 enhancer factor (GEF) and myocyte enhancer factor 2 (MEF2) have been shown to be important for normal GLUT4 expression because deletion or truncation of the consensus sequences on the promoter causes depressed GLUT4 mRNA expression. This led to the current study to investigate possible roles for GEF and MEF2 in mediating the activation of GLUT4 gene transcription in response to AMPK. Here we show that, although AMPK does not appear to phosphorylate MEF2A, AMPK directly phosphorylates the GEF protein in vitro. MEF2 and GEF are activated in response to AMPK as we observed translocation of both to the nucleus after AICAR treatment. Nuclear MEF2 protein content was increased after 2 h, and GEF protein was increased in the nucleus 1 and 2 h post-AICAR treatment. Last, GEF and MEF2 increase in binding to the GLUT4 promoter within 2 h after AICAR treatment. Thus we conclude that GEF and MEF2 mediate the AMPK-induced increase in transcription of skeletal muscle GLUT4. AMPK can phosphorylate GEF and in response to AICAR, GEF, and MEF2 translocate to the nucleus and have increased binding to the GLUT4 promoter.
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Affiliation(s)
- Burton F Holmes
- Department of Exercise and Sport Science, Human Performance Laboratory, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
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Basile V, Mantovani R, Imbriano C. DNA damage promotes histone deacetylase 4 nuclear localization and repression of G2/M promoters, via p53 C-terminal lysines. J Biol Chem 2005; 281:2347-57. [PMID: 16293626 DOI: 10.1074/jbc.m507712200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Repression of G(2)/M promoters after DNA damage is an active mechanism that requires the p53 tumor suppressor. We have recently found that histone deacetylase 4 (HDAC4) is recruited on NF-Y-dependent repressed promoters. In this report, we describe the relationship between p53 and HDAC4 recruitment following DNA damage using immunofluorescence, chromatin immunoprecipitation, and transfection experiments. HDAC4 shuttles from the cytoplasm into the nucleus, following DNA damage, independently of the activation of p53 and becomes associated with promoters through a p53-dependent mechanism. The C-terminal lysines of p53, which are acetylated and methylated, are required for HDAC4 recruitment and transcriptional repression. Trichostatin treatment, but not HDAC4 functional inactivation, relieves the adriamycin-mediated repression of G(2)/M promoters. Our results indicate that HDAC4 is a component of the DNA damage response and that post-translational modifications of p53 are important for repression of G(2)/M genes.
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Affiliation(s)
- Valentina Basile
- Dipartimento di Biologia Animale, Università di Modena e Reggio, Via Campi 213/d, 41100 Modena, Italy
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Lynch J, Guo L, Gelebart P, Chilibeck K, Xu J, Molkentin JD, Agellon LB, Michalak M. Calreticulin signals upstream of calcineurin and MEF2C in a critical Ca(2+)-dependent signaling cascade. ACTA ACUST UNITED AC 2005; 170:37-47. [PMID: 15998798 PMCID: PMC2171392 DOI: 10.1083/jcb.200412156] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We uncovered a new pathway of interplay between calreticulin and myocyte-enhancer factor (MEF) 2C, a cardiac-specific transcription factor. We establish that calreticulin works upstream of calcineurin and MEF2C in a Ca2+-dependent signal transduction cascade that links the endoplasmic reticulum and the nucleus during cardiac development. In the absence of calreticulin, translocation of MEF2C to the nucleus is compromised. This defect is reversed by calreticulin itself or by a constitutively active form of calcineurin. Furthermore, we show that expression of the calreticulin gene itself is regulated by MEF2C in vitro and in vivo and that, in turn, increased expression of calreticulin affects MEF2C transcriptional activity. The present findings provide a clear molecular explanation for the embryonic lethality observed in calreticulin-deficient mice and emphasize the importance of calreticulin in the early stages of cardiac development. Our study illustrates the existence of a positive feedback mechanism that ensures an adequate supply of releasable Ca2+ is maintained within the cell for activation of calcineurin and, subsequently, for proper functioning of MEF2C.
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Affiliation(s)
- Jeffrey Lynch
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Yang XJ, Grégoire S. Class II histone deacetylases: from sequence to function, regulation, and clinical implication. Mol Cell Biol 2005; 25:2873-84. [PMID: 15798178 PMCID: PMC1069616 DOI: 10.1128/mcb.25.8.2873-2884.2005] [Citation(s) in RCA: 320] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Xiang-Jiao Yang
- Molecular Oncology Group, Royal Victoria Hospital, Room H5.41, McGill University Health Center, 687 Pine Ave. West, Montréal, Quebec H3A 1A1, Canada.
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40
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Deng X, Ewton DZ, Mercer SE, Friedman E. Mirk/dyrk1B decreases the nuclear accumulation of class II histone deacetylases during skeletal muscle differentiation. J Biol Chem 2005; 280:4894-905. [PMID: 15546868 DOI: 10.1074/jbc.m411894200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mirk/dyrk1B is a member of the dyrk/minibrain family of serine/threonine kinases that mediate the transition from growth to differentiation in lower eukaryotes and mammals. Depletion of endogenous Mirk from C2C12 myoblasts by RNA interference blocks skeletal muscle differentiation (Deng, X., Ewton, D., Pawlikowski, B., Maimone, M., and Friedman, E. (2003) J. Biol. Chem. 278, 41347-41354). We now demonstrate that knockdown of Mirk blocks transcription of the muscle regulatory factor myogenin. Co-expression of Mirk with MEF2C, but not MyoD or Myf5, enhanced activation of the myogenin promoter in a Mirk kinase-dependent manner. Mirk activated MEF2 not through direct phosphorylation of MEF2 but by phosphorylation of its inhibitors, the class II histone deacetylases (HDACs). MEF2 is sequestered by class II HDACs such as HDAC5 and MEF2-interacting transcriptional repressor (MITR). Mirk antagonized the inhibition of MEF2C by MITR, whereas kinase-inactive Mirk was ineffective. Mirk phosphorylates class II HDACs at a conserved site within the nuclear localization region, reducing their nuclear accumulation in a dose-dependent and kinase-dependent manner. Moreover, less mutant MITR phosphomimetic at the Mirk phosphorylation site localized in the nucleus than wild-type MITR. Regulation of class II HDACs occurs by multiple mechanisms. Others have shown that calcium signaling leads to phosphorylation of HDACs at 14-3-3-binding sites, blocking their association with MEF2 within the nucleus. Mirk provides another level of regulation. Mirk is induced within the initial 24 h of myogenic differentiation and enables MEF2 to transcribe the myogenin gene by decreasing the nuclear accumulation of class II HDACs.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Blotting, Northern
- Butyrates/pharmacology
- Cell Differentiation
- Cell Line
- Cell Nucleus/metabolism
- DNA/chemistry
- DNA-Binding Proteins/metabolism
- Dose-Response Relationship, Drug
- Down-Regulation
- Electrophoresis, Polyacrylamide Gel
- Gene Expression Regulation, Enzymologic
- Glutathione Transferase/metabolism
- Histone Deacetylases/metabolism
- Luciferases/metabolism
- MEF2 Transcription Factors
- Mice
- Mitogen-Activated Protein Kinases/biosynthesis
- Molecular Sequence Data
- Muscle Proteins/metabolism
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- MyoD Protein/metabolism
- Myogenic Regulatory Factor 5
- Myogenic Regulatory Factors/metabolism
- Myogenin/genetics
- Myogenin/metabolism
- NIH 3T3 Cells
- Oligonucleotide Array Sequence Analysis
- Phosphorylation
- Plasmids/metabolism
- Promoter Regions, Genetic
- Protein Serine-Threonine Kinases/biosynthesis
- Protein-Tyrosine Kinases/biosynthesis
- RNA Interference
- RNA, Messenger/metabolism
- RNA, Small Interfering/metabolism
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Subcellular Fractions
- Trans-Activators/metabolism
- Transcription Factors
- Transcription, Genetic
- Transfection
- Up-Regulation
- Dyrk Kinases
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Affiliation(s)
- Xiaobing Deng
- Department of Pathology, Upstate Medical University, State University of New York, Syracuse, New York 13210, USA
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41
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Abstract
The myocyte enhancer factor 2 (MEF2) transcription factors were originally identified, as their family name implies, on the basis of their role in muscle differentiation. Expression of the four MEF2 proteins, however, is not restricted to contractile tissue. While it has been known for more than a decade that MEF2s are abundantly expressed in neurons, their contributions to the development and function of the nervous system are only now being elucidated. Interestingly, the emerging mechanisms regulating MEF2 in neurons have significant parallels with the regulatory mechanisms in muscle, despite the quite distinct identities of these two electrically excitable tissues. The goal of this chapter is to provide an introduction to those regulatory mechanisms and their consequences for brain development. As such, we first provide an overview of MEF2 itself and its expression within the central nervous system. The second part of this chapter describes the signaling molecules that regulate MEF2 transcriptional activity and their contributions to MEF2 function. The third part of this chapter discusses the role of MEF2 proteins in the developing nervous system and compares the analogous functions of this protein family in muscle and brain.
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Affiliation(s)
- Aryaman K Shalizi
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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42
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Przyborski JM, Lanzer M. Protein transport and trafficking inPlasmodium falciparum-infected erythrocytes. Parasitology 2004; 130:373-88. [PMID: 15830811 DOI: 10.1017/s0031182004006729] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The human malarial parasitePlasmodium falciparumextensively modifies its host erythrocyte, and to this end, is faced with an interesting challenge. It must not only sort proteins to common organelles such as endoplasmic reticulum, Golgi and mitochondria, but also target proteins across the ‘extracellular’ cytosol of its host cell. Furthermore, as a member of the phylum Apicomplexa, the parasite has to sort proteins to novel organelles such as the apicoplast, micronemes and rhoptries. In order to overcome these difficulties, the parasite has created a novel secretory system, which has been characterized in ever-increasing detail in the past decade. Along with the ‘hardware’ for a secretory system, the parasite also needs to ‘program’ proteins to enable high fidelity sorting to their correct subcellular location. The nature of these sorting signals has remained until relatively recently, enigmatic. Experimental work has now begun to dissect the sorting signals responsible for correct subcellular targeting of parasite-encoded proteins. In this review we summarize the current understanding of such signals, and comment on their role in protein sorting in this organism, which may become a model for the study of novel protein trafficking mechanisms.
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Affiliation(s)
- J M Przyborski
- Hygiene Institute, Department of Parasitology, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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43
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Abstract
Glucose transport into muscle is important for the maintenance of normoglycemia. Thus, understanding mechanisms that regulate expression of GLUT4, the main glucose transporter in skeletal muscle, is important to identify targets for the treatment of diabetes. Exercise increases the expression of GLUT4 mRNA and protein, and we have been investigating the mechanisms involved. Transcription of the GLUT4 gene is transiently activated after an acute bout of exercise and GLUT4 protein can be increased as much as two- to threefold after a few days of repeated exercise bouts. Studies of the GLUT4 promoter have identified two sets of DNA sequences that are important for metabolic regulation and also for increased transcription of the gene in response to exercise. These DNA elements have been shown to bind the transcription factors myocyte enhancer factor 2 (MEF2) and GLUT4 enhancer factor (GEF). The mechanisms that activate these proteins remain one of the important areas of research in this field. Signals that link muscle contraction to the activation of transcription factors (MEF2, GEF) involved in increased expression of GLUT4 during exercise is another area needing further research. Two signals that show promise are changes in the energy charge (acting through AMP activated kinase [AMPK]) and changes in intracellular calcium (acting through calcineurin [a calcium-calmodulin activated phosphatase] and calcium-calmodulin activated kinase [CAMK]). There is good evidence that both increased AMPK activity and increased CAMK activity cause increased transcription of the GLUT4 gene. It remains to be demonstrated that exercise is acting through one or both of these mechanisms.
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Affiliation(s)
- Burton Holmes
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
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44
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Chauchereau A, Mathieu M, de Saintignon J, Ferreira R, Pritchard LL, Mishal Z, Dejean A, Harel-Bellan A. HDAC4 mediates transcriptional repression by the acute promyelocytic leukaemia-associated protein PLZF. Oncogene 2004; 23:8777-84. [PMID: 15467736 DOI: 10.1038/sj.onc.1208128] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PLZF, the promyelocytic leukaemia zinc-finger protein, is a transcriptional repressor essential to development. In some acute leukaemias, a chromosomal translocation fusing the PLZF gene to that encoding the retinoic acid receptor RARalpha gives rise to a fusion protein, PLZF-RARalpha, thought to be responsible for constitutive repression of differentiation-associated genes in these cells. Repression by both PLZF and PLZF-RARalpha is sensitive to the histone deacetylase inhibitor TSA, and PLZF was previously shown to interact physically with HDAC1, a class I histone deacetylase. We here asked whether class II histone deacetylases, known to be generally involved in differentiation processes, participate in the repression mediated by PLZF and PLZF-RARalpha, and found that PLZF interacts with HDAC4 in both GST-pull-down and co-immunoprecipitation assays. Furthermore, HDAC4 is indeed involved in PLZF and PLZF-RARalpha-mediated repression, since an enzymatically dead mutant of HDAC4 released the repression, as did an siRNA that blocks HDAC4 expression. Taken together, our data indicate that recruitment of HDAC4 is necessary for PLZF-mediated repression in both normal and leukaemic cells.
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Affiliation(s)
- Anne Chauchereau
- UPR 9079 CNRS-Ligue Nationale Contre le Cancer, Institut André Lwoff, 7 rue Guy Môquet, 94800 Villejuif, France
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45
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Liu F, Dowling M, Yang XJ, Kao GD. Caspase-mediated specific cleavage of human histone deacetylase 4. J Biol Chem 2004; 279:34537-46. [PMID: 15205465 DOI: 10.1074/jbc.m402475200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Histone deacetylase 4 (HDAC4) is a class II HDAC implicated in controlling gene expression important for diverse cellular functions, but little is known about how its expression and stability are regulated. We report here that this deacetylase is unusually unstable, with a half-life of less than 8 h. Consistent with the instability of HDAC4 protein, its mRNA was also highly unstable (with a half-life of less than 4 h). The degradation of HDAC4 could be accelerated by exposure of cells to ultraviolet irradiation. HDAC4 degradation was not dependent on proteasome or CRM1-mediated export activity but instead was caspase-dependent and was detectable in diverse human cancer lines. Of two potential caspase consensus motifs in HDAC4, both lying within a region containing proline-, glutamic acid-, serine-, and threonine-rich (PEST) sequences, we identified, by site-directed mutagenesis, Asp-289 as the prime cleavage site. Notably, this residue is not conserved among other class IIa members, HDAC5, -7, and -9. Finally, the induced expression of caspase-cleavable HDAC4 led to markedly increased apoptosis. These results therefore unexpectedly link the regulation of HDAC4 protein stability to caspases, enzymes that are important for controlling cell death and differentiation.
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Affiliation(s)
- Fang Liu
- Department of Radiation Oncology, University of Pennsylvania School of Medicine, John Morgan 180H, Philadelphia, PA 19104, USA
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46
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Halkidou K, Cook S, Leung HY, Neal DE, Robson CN. Nuclear accumulation of histone deacetylase 4 (HDAC4) coincides with the loss of androgen sensitivity in hormone refractory cancer of the prostate. Eur Urol 2004; 45:382-9; author reply 389. [PMID: 15036687 DOI: 10.1016/j.eururo.2003.10.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVES To examine the effect of androgen treatment upon histone deacetylase 4 (HDAC4) localisation and, thus, enzymatic function in androgen sensitive prostate cancer (CaP) models. To study HDAC4 expression in benign prostatic hyperplasia, primary and hormone refractory (HR) CaP and to investigate the involvement of histone deacetylase activity in the development of the androgen insensitive phenotype. METHODS Immunohistochemical staining of prostate sections of both benign tissue and primary and hormone relapsed prostate cancer, as well as of the CWR22 mouse xenograft model, and indirect quantitative immunofluorescence staining of endogenous HDAC4 in LNCaP cells. RESULTS HDAC4 is recruited to the nuclei of HR cancer cells, where it may exert an inhibitory effect on differentiation and contribute to the development of the aggressive phenotype of late stage CaP. The above may result from the loss of androgen responsiveness characterising HR CaP, since HDAC4 nuclear localisation is regulated by androgens in androgen responsive systems (i.e. LNCaP, CWR22) reflecting earlier phase disease. CONCLUSIONS HDAC4 may contribute to the development of HR CaP and, therefore, constitute a potential therapeutic target, particularly in the most lethal phase of androgen independence.
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Affiliation(s)
- K Halkidou
- School of Surgical and Reproductive Sciences, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, UK
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47
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Paroni G, Mizzau M, Henderson C, Del Sal G, Schneider C, Brancolini C. Caspase-dependent regulation of histone deacetylase 4 nuclear-cytoplasmic shuttling promotes apoptosis. Mol Biol Cell 2004; 15:2804-18. [PMID: 15075374 PMCID: PMC420104 DOI: 10.1091/mbc.e03-08-0624] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Histone deacetylases (HDACs) are important regulators of gene expression as part of transcriptional corepressor complexes. Here, we demonstrate that caspases can repress the activity of the myocyte enhancer factor (MEF)2C transcription factor by regulating HDAC4 processing. Cleavage of HDAC4 occurs at Asp 289 and disjoins the carboxy-terminal fragment, localized into the cytoplasm, from the amino-terminal fragment, which accumulates into the nucleus. In the nucleus, the caspase-generated fragment of HDAC4 is able to trigger cytochrome c release from mitochondria and cell death in a caspase-9-dependent manner. The caspase-cleaved amino-terminal fragment of HDAC4 acts as a strong repressor of the transcription factor MEF2C, independently from the HDAC domain. Removal of amino acids 166-289 from the caspase-cleaved fragment of HDAC4 abrogates its ability to repress MEF2 transcription and to induce cell death. Caspase-2 and caspase-3 cleave HDAC4 in vitro and caspase-3 is critical for HDAC4 cleavage in vivo during UV-induced apoptosis. After UV irradiation, GFP-HDAC4 translocates into the nucleus coincidentally/immediately before the retraction response, but clearly before nuclear fragmentation. Together, our data indicate that caspases could specifically modulate gene repression and apoptosis through the proteolyic processing of HDAC4.
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Affiliation(s)
- Gabriela Paroni
- Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Biologia-Università di Udine, 33100 Udine, Italy
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48
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Wang L, Fan C, Topol SE, Topol EJ, Wang Q. Mutation of MEF2A in an inherited disorder with features of coronary artery disease. Science 2003; 302:1578-81. [PMID: 14645853 PMCID: PMC1618876 DOI: 10.1126/science.1088477] [Citation(s) in RCA: 278] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The early genetic pathway(s) triggering the pathogenesis of coronary artery disease (CAD) and myocardial infarction (MI) remain largely unknown. Here, we describe an autosomal dominant form of CAD/MI (adCAD1) that is caused by the deletion of seven amino acids in transcription factor MEF2A. The deletion disrupts nuclear localization of MEF2A, reduces MEF2A-mediated transcription activation, and abolishes synergistic activation by MEF2A and by the transcription factor GATA-1 through a dominant-negative mechanism. The MEF2A protein demonstrates strong expression in the endothelium of coronary arteries. These results identify a pathogenic gene for a familial vascular disease with features of CAD and implicate the MEF2A signaling pathway in the pathogenesis of CAD/MI.
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Affiliation(s)
- Lejin Wang
- Center for Cardiovascular Genetics, Department of Cardiovascular Medicine, and Center for Molecular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation
- Department of Molecular Medicine
| | - Chun Fan
- Center for Cardiovascular Genetics, Department of Cardiovascular Medicine, and Center for Molecular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation
- Department of Molecular Medicine
| | - Sarah E. Topol
- Center for Cardiovascular Genetics, Department of Cardiovascular Medicine, and Center for Molecular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation
| | - Eric J. Topol
- Center for Cardiovascular Genetics, Department of Cardiovascular Medicine, and Center for Molecular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation
- Department of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
- *To whom correspondence should be addressed. E-mail: (Q.W.) and (E.J.T.)
| | - Qing Wang
- Center for Cardiovascular Genetics, Department of Cardiovascular Medicine, and Center for Molecular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation
- Department of Molecular Medicine
- *To whom correspondence should be addressed. E-mail: (Q.W.) and (E.J.T.)
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49
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Abstract
Coronary artery disease (CAD) that results from lesions of the vascular wall is a major cause of myocardial infarction (MI) and stroke. A human pedigree with a predisposition to CAD and MI has been shown to harbor a mutation in the MEF2A transcription factor. These findings reveal a new function for this regulator of cardiovascular development and raise intriguing questions about the underlying mechanisms of CAD.
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Affiliation(s)
- Eric N Olson
- Department of Molecular Biology, University of Texas, Southwestern Medical Center, Dallas, TX 75390, USA.
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50
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Davis FJ, Gupta M, Camoretti-Mercado B, Schwartz RJ, Gupta MP. Calcium/calmodulin-dependent protein kinase activates serum response factor transcription activity by its dissociation from histone deacetylase, HDAC4. Implications in cardiac muscle gene regulation during hypertrophy. J Biol Chem 2003; 278:20047-58. [PMID: 12663674 DOI: 10.1074/jbc.m209998200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serum response factor (SRF) plays a pivotal role in cardiac myocyte development, muscle gene transcription, and hypertrophy. Previously, elevation of intracellular levels of Ca2+ was shown to activate SRF function without involving the Ets family of tertiary complex factors through an unknown regulatory mechanism. Here, we tested the hypothesis that the chromatin remodeling enzymes of class II histone deacetylases (HDAC4) regulate SRF activity in a Ca2+-sensitive manner. Expression of HDAC4 profoundly repressed SRF-mediated transcription in both muscle and nonmuscle cells. Protein interaction studies demonstrated physical association of HDAC4 with SRF in living cells. The SRF/HDAC4 co-association was disrupted by treatment of cells with hypertrophic agonists such as angiotensin-II and a Ca2+ ionophore, ionomycin. Furthermore, activation of Ca2+/calmodulin-dependent protein kinase (CaMK)-IV prevented SRF/HDAC4 interaction and derepressed SRF-dependent transcription activity. The SRF.HDAC4 complex was localized to the cell nucleus, and the activated CaMK-IV disrupted HDAC4/SRF association, leading to export of HDAC4 from the nucleus and stimulation of SRF transcription activity. Thus, these results identify SRF as a functional interacting target of HDAC4 and define a novel tertiary complex factor-independent mechanism for SRF activation by Ca2+/CaMK-mediated signaling.
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