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Karafoulidou E, Kesidou E, Theotokis P, Konstantinou C, Nella MK, Michailidou I, Touloumi O, Polyzoidou E, Salamotas I, Einstein O, Chatzisotiriou A, Boziki MK, Grigoriadis N. Systemic LPS Administration Stimulates the Activation of Non-Neuronal Cells in an Experimental Model of Spinal Muscular Atrophy. Cells 2024; 13:785. [PMID: 38727321 PMCID: PMC11083572 DOI: 10.3390/cells13090785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/27/2024] [Accepted: 05/02/2024] [Indexed: 05/13/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by deficiency of the survival motor neuron (SMN) protein. Although SMA is a genetic disease, environmental factors contribute to disease progression. Common pathogen components such as lipopolysaccharides (LPS) are considered significant contributors to inflammation and have been associated with muscle atrophy, which is considered a hallmark of SMA. In this study, we used the SMNΔ7 experimental mouse model of SMA to scrutinize the effect of systemic LPS administration, a strong pro-inflammatory stimulus, on disease outcome. Systemic LPS administration promoted a reduction in SMN expression levels in CNS, peripheral lymphoid organs, and skeletal muscles. Moreover, peripheral tissues were more vulnerable to LPS-induced damage compared to CNS tissues. Furthermore, systemic LPS administration resulted in a profound increase in microglia and astrocytes with reactive phenotypes in the CNS of SMNΔ7 mice. In conclusion, we hereby show for the first time that systemic LPS administration, although it may not precipitate alterations in terms of deficits of motor functions in a mouse model of SMA, it may, however, lead to a reduction in the SMN protein expression levels in the skeletal muscles and the CNS, thus promoting synapse damage and glial cells' reactive phenotype.
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Affiliation(s)
- Eleni Karafoulidou
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Evangelia Kesidou
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Paschalis Theotokis
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Chrystalla Konstantinou
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Maria-Konstantina Nella
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Iliana Michailidou
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Olga Touloumi
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Eleni Polyzoidou
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Ilias Salamotas
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Ofira Einstein
- Department of Physical Therapy, Faculty of Health Sciences, Ariel University, Ariel 40700, Israel;
| | - Athanasios Chatzisotiriou
- Department of Physiology, Medical School, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece;
| | - Marina-Kleopatra Boziki
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
| | - Nikolaos Grigoriadis
- Laboratory of Experimental Neurology and Neuroimmunology, 2nd Neurological University Department, AHEPA General Hospital of Thessaloniki, Faculty of Health Science, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (E.K.); (E.K.); (P.T.); (C.K.); (M.-K.N.); (I.M.); (O.T.); (E.P.); (I.S.)
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Riboldi GM, Faravelli I, Rinchetti P, Lotti F. SMN post-translational modifications in spinal muscular atrophy. Front Cell Neurosci 2023; 17:1092488. [PMID: 36874214 PMCID: PMC9981653 DOI: 10.3389/fncel.2023.1092488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/26/2023] [Indexed: 02/19/2023] Open
Abstract
Since its first identification as the gene responsible for spinal muscular atrophy (SMA), the range of survival motor neuron (SMN) protein functions has increasingly expanded. This multimeric complex plays a crucial role in a variety of RNA processing pathways. While its most characterized function is in the biogenesis of ribonucleoproteins, several studies have highlighted the SMN complex as an important contributor to mRNA trafficking and translation, axonal transport, endocytosis, and mitochondria metabolism. All these multiple functions need to be selectively and finely modulated to maintain cellular homeostasis. SMN has distinct functional domains that play a crucial role in complex stability, function, and subcellular distribution. Many different processes were reported as modulators of the SMN complex activities, although their contribution to SMN biology still needs to be elucidated. Recent evidence has identified post-translational modifications (PTMs) as a way to regulate the pleiotropic functions of the SMN complex. These modifications include phosphorylation, methylation, ubiquitination, acetylation, sumoylation, and many other types. PTMs can broaden the range of protein functions by binding chemical moieties to specific amino acids, thus modulating several cellular processes. Here, we provide an overview of the main PTMs involved in the regulation of the SMN complex with a major focus on the functions that have been linked to SMA pathogenesis.
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Affiliation(s)
| | | | | | - Francesco Lotti
- Center for Motor Neuron Biology and Diseases, Departments of Pathology & Cell Biology, and Neurology, Columbia University Irving Medical Center, New York, NY, United States
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Detering NT, Schüning T, Hensel N, Claus P. The phospho-landscape of the survival of motoneuron protein (SMN) protein: relevance for spinal muscular atrophy (SMA). Cell Mol Life Sci 2022; 79:497. [PMID: 36006469 PMCID: PMC11071818 DOI: 10.1007/s00018-022-04522-9] [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: 03/21/2022] [Revised: 07/27/2022] [Accepted: 08/09/2022] [Indexed: 11/03/2022]
Abstract
Spinal muscular atrophy (SMA) is caused by low levels of the survival of motoneuron (SMN) Protein leading to preferential degeneration of lower motoneurons in the ventral horn of the spinal cord and brain stem. However, the SMN protein is ubiquitously expressed and there is growing evidence of a multisystem phenotype in SMA. Since a loss of SMN function is critical, it is important to decipher the regulatory mechanisms of SMN function starting on the level of the SMN protein itself. Posttranslational modifications (PTMs) of proteins regulate multiple functions and processes, including activity, cellular trafficking, and stability. Several PTM sites have been identified within the SMN sequence. Here, we map the identified SMN PTMs highlighting phosphorylation as a key regulator affecting localization, stability and functions of SMN. Furthermore, we propose SMN phosphorylation as a crucial factor for intracellular interaction and cellular distribution of SMN. We outline the relevance of phosphorylation of the spinal muscular atrophy (SMA) gene product SMN with regard to basic housekeeping functions of SMN impaired in this neurodegenerative disease. Finally, we compare SMA patient mutations with putative and verified phosphorylation sites. Thus, we emphasize the importance of phosphorylation as a cellular modulator in a clinical perspective as a potential additional target for combinatorial SMA treatment strategies.
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Affiliation(s)
- Nora Tula Detering
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Tobias Schüning
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Niko Hensel
- Ottawa Hospital Research Institute (OHRI), Ottawa, Canada
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Peter Claus
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany.
- Center for Systems Neuroscience (ZSN), Hannover, Germany.
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Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by mutations in SMN1 (encoding survival motor neuron protein (SMN)). Reduced expression of SMN leads to loss of α-motor neurons, severe muscle weakness and often early death. Standard-of-care recommendations for multidisciplinary supportive care of SMA were established in the past few decades. However, improved understanding of the pathogenetic mechanisms of SMA has led to the development of different therapeutic approaches. Three treatments that increase SMN expression by distinct molecular mechanisms, administration routes and tissue biodistributions have received regulatory approval with others in clinical development. The advent of the new therapies is redefining standards of care as in many countries most patients are treated with one of the new therapies, leading to the identification of emerging new phenotypes of SMA and a renewed characterization of demographics owing to improved patient survival.
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Zhang Y, Chen X, Wang Q, Du C, Lu W, Yuan H, Zhang Z, Li D, Ling X, Ren X, Zhao Y, Su Q, Xing Z, Qin Y, Yang X, Shen Y, Wu H, Qi Y. Hyper-SUMOylation of SMN induced by SENP2 deficiency decreases its stability and leads to spinal muscular atrophy-like pathology. J Mol Med (Berl) 2021; 99:1797-1813. [PMID: 34628513 DOI: 10.1007/s00109-021-02130-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/05/2021] [Accepted: 08/09/2021] [Indexed: 11/28/2022]
Abstract
Spinal muscular atrophy (SMA), a degenerative motor neuron disease and a leading cause of infant mortality, is caused by loss of functional survival motor neuron (SMN) protein due to SMN1 gene mutation. Here, using mouse and cell models for behavioral and histological studies, we found that SENP2 (SUMO/sentrin-specific protease 2)-deficient mice developed a notable SMA-like pathology phenotype with significantly decreased muscle fibers and motor neurons. At the molecular level, SENP2 deficiency in mice did not affect transcription but decreased SMN protein levels by promoting the SUMOylation of SMN. SMN was modified by SUMO2 with the E3 PIAS2α and deconjugated by SENP2. SUMOylation of SMN accelerated its degradation by the ubiquitin-proteasome degradation pathway with the ubiquitin E1 UBA1 (ubiquitin-like modifier activating enzyme 1) and E3 ITCH. SUMOylation of SMN increased its acetylation to inhibit the formation of Cajal bodies (CBs). These results showed that SENP2 deficiency induced hyper-SUMOylation of the SMN protein, which further affected the stability and functions of the SMN protein, eventually leading to the SMA-like phenotype. Thus, we uncovered the important roles for hyper-SUMOylation of SMN induced by SENP2 deficiency in motor neurons and provided a novel targeted therapeutic strategy for SMA. KEY MESSAGES: SENP2 deficiency enhanced the hyper-SUMOylation of SMN and promoted the degradation of SMN by the ubiquitin-proteasome pathway. SUMOylation increased the acetylation of SMN to inhibit CB formation. SENP2 deficiency caused hyper-SUMOylation of SMN protein, which further affected the stability and functions of SMN protein and eventually led to the occurrence of SMA-like pathology.
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Affiliation(s)
- Yuhong Zhang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Xu Chen
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Qiqi Wang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Congcong Du
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Wenbin Lu
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Hong Yuan
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Zhenzhen Zhang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Danqing Li
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Xing Ling
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Xiang Ren
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Yang Zhao
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Qi Su
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Zhengcao Xing
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Yuanyuan Qin
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Xinyi Yang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Yajie Shen
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China
| | - Hongmei Wu
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China.
| | - Yitao Qi
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, Shaanxi, China.
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Protein expression reveals a molecular sexual identity of avian primordial germ cells at pre-gonadal stages. Sci Rep 2021; 11:19236. [PMID: 34584135 PMCID: PMC8478952 DOI: 10.1038/s41598-021-98454-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 09/06/2021] [Indexed: 11/11/2022] Open
Abstract
In poultry, in vitro propagated primordial germ cells (PGCs) represent an important tool for the cryopreservation of avian genetic resources. However, several studies have highlighted sexual differences exhibited by PGCs during in vitro propagation, which may compromise their reproductive capacities. To understand this phenomenon, we compared the proteome of pregonadal migratory male (ZZ) and female (ZW) chicken PGCs propagated in vitro by quantitative proteomic analysis using a GeLC-MS/MS strategy. Many proteins were found to be differentially abundant in chicken male and female PGCs indicating their early sexual identity. Many of the proteins more highly expressed in male PGCs were encoded by genes localised to the Z sex chromosome. This suggests that the known lack of dosage compensation of the transcription of Z-linked genes between sexes persists at the protein level in PGCs, and that this may be a key factor of their autonomous sex differentiation. We also found that globally, protein differences do not closely correlate with transcript differences indicating a selective translational mechanism in PGCs. Male and female PGC expressed protein sets were associated with differential biological processes and contained proteins known to be biologically relevant for male and female germ cell development, respectively. We also discovered that female PGCs have a higher capacity to uptake proteins from the cell culture medium than male PGCs. This study presents the first evidence of an early predetermined sex specific cell fate of chicken PGCs and their sexual molecular specificities which will enable the development of more precise sex-specific in vitro culture conditions for the preservation of avian genetic resources.
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Sewduth RN, Baietti MF, Sablina AA. Cracking the Monoubiquitin Code of Genetic Diseases. Int J Mol Sci 2020; 21:ijms21093036. [PMID: 32344852 PMCID: PMC7246618 DOI: 10.3390/ijms21093036] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/20/2020] [Accepted: 04/23/2020] [Indexed: 12/26/2022] Open
Abstract
Ubiquitination is a versatile and dynamic post-translational modification in which single ubiquitin molecules or polyubiquitin chains are attached to target proteins, giving rise to mono- or poly-ubiquitination, respectively. The majority of research in the ubiquitin field focused on degradative polyubiquitination, whereas more recent studies uncovered the role of single ubiquitin modification in important physiological processes. Monoubiquitination can modulate the stability, subcellular localization, binding properties, and activity of the target proteins. Understanding the function of monoubiquitination in normal physiology and pathology has important therapeutic implications, as alterations in the monoubiquitin pathway are found in a broad range of genetic diseases. This review highlights a link between monoubiquitin signaling and the pathogenesis of genetic disorders.
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Affiliation(s)
- Raj Nayan Sewduth
- VIB-KU Leuven Center for Cancer Biology, VIB, Herestraat 49, 3000 Leuven, Belgium; (R.N.S.); (M.F.B.)
- Department of Oncology, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Maria Francesca Baietti
- VIB-KU Leuven Center for Cancer Biology, VIB, Herestraat 49, 3000 Leuven, Belgium; (R.N.S.); (M.F.B.)
- Department of Oncology, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Anna A. Sablina
- VIB-KU Leuven Center for Cancer Biology, VIB, Herestraat 49, 3000 Leuven, Belgium; (R.N.S.); (M.F.B.)
- Department of Oncology, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
- Correspondence:
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Martín-Doncel E, Rojas AM, Cantarero L, Lazo PA. VRK1 functional insufficiency due to alterations in protein stability or kinase activity of human VRK1 pathogenic variants implicated in neuromotor syndromes. Sci Rep 2019; 9:13381. [PMID: 31527692 PMCID: PMC6746721 DOI: 10.1038/s41598-019-49821-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 08/30/2019] [Indexed: 12/12/2022] Open
Abstract
Very rare polymorphisms in the human VRK1 (vaccinia-related kinase 1) gene have been identified in complex neuromotor phenotypes associated to spinal muscular atrophy (SMA), pontocerebellar hypoplasia (PCH), microcephaly, amyotrophic lateral sclerosis (ALS) and distal motor neuron dysfunctions. The mechanisms by which these VRK1 variant proteins contribute to the pathogenesis of these neurological syndromes are unknown. The syndromes are manifested when both of these rare VRK1 polymorphic alleles are implicated, either in homozygosis or compound heterozygosis. In this report, to identify the common underlying pathogenic mechanism of VRK1 polymorphisms, we have studied all human VRK1 variants identified in these neurological phenotypes from a biochemical point of view by molecular modeling, protein stability and kinase activity assays. Molecular modelling predicted that VRK1 variant proteins are either unstable or have an altered kinase activity. The stability and kinase activity of VRK1 pathogenic variants detected two groups. One composed by variants with a reduced protein stability: R133C, R358X, L195V, G135R and R321C. The other group includes VRK1variants with a reduced kinase activity tested on several substrates: histones H3 and H2AX, p53, c-Jun, coilin and 53BP1, a DNA repair protein. VRK1 variants with reduced kinase activity are H119R, R133C, G135R, V236M, R321C and R358X. The common underlying effect of VRK1 pathogenic variants with reduced protein stability or kinase activity is a functional insufficiency of VRK1 in patients with neuromotor developmental syndromes. The G135 variant cause a defective formation of 53BP1 foci in response to DNA damage, and loss Cajal bodies assembled on coilin.
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Affiliation(s)
- Elena Martín-Doncel
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, Salamanca, Spain
| | - Ana M Rojas
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- Instituto de Biomedicina de Sevilla (IBIS), CSIC-Universidad de Sevilla, Hospital Universitario Virgen del Rocío, Sevilla, Spain
| | - Lara Cantarero
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, Salamanca, Spain
- Laboratorio de Neurogenética y Medicina Molecular, Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain
| | - Pedro A Lazo
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, Salamanca, Spain.
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, Salamanca, Spain.
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Gundogdu M, Walden H. Structural basis of generic versus specific E2-RING E3 interactions in protein ubiquitination. Protein Sci 2019; 28:1758-1770. [PMID: 31340062 DOI: 10.1002/pro.3690] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/11/2019] [Accepted: 07/11/2019] [Indexed: 12/21/2022]
Abstract
Protein ubiquitination is a fundamental regulatory component in eukaryotic cell biology, where a cascade of ubiquitin activating (E1), conjugating (E2), and ligating (E3) enzymes assemble distinct ubiquitin signals on target proteins. E2s specify the type of ubiquitin signal generated, while E3s associate with the E2~Ub conjugate and select the substrate for ubiquitination. Thus, producing the right ubiquitin signal on the right target requires the right E2-E3 pair. The question of how over 600 E3s evolved to discriminate between 38 structurally related E2s has therefore been an area of intensive research, and with over 50 E2-E3 complex structures generated to date, the answer is beginning to emerge. The following review discusses the structural basis of generic E2-RING E3 interactions, contrasted with emerging themes that reveal how specificity can be achieved.
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Affiliation(s)
- Mehmet Gundogdu
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Helen Walden
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Han KJ, Wu Z, Pearson CG, Peng J, Song K, Liu CW. Deubiquitylase USP9X maintains centriolar satellite integrity by stabilizing pericentriolar material 1 protein. J Cell Sci 2019; 132:jcs.221663. [PMID: 30584065 DOI: 10.1242/jcs.221663] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 12/19/2018] [Indexed: 12/12/2022] Open
Abstract
Centriolar satellites are small cytoplasmic granules that play important roles in regulating the formation of centrosomes and primary cilia. Ubiquitylation of satellite proteins, including the core satellite scaffold protein pericentriolar material 1 (PCM1), regulates centriolar satellite integrity. Currently, deubiquitylases that control centriolar satellite integrity have not been identified. In this study, we find that the deubiquitylase USP9X binds PCM1, and antagonizes PCM1 ubiquitylation to protect it from proteasomal degradation. Knockdown of USP9X in human cell lines reduces PCM1 protein levels, disrupts centriolar satellite particles and causes localization of satellite proteins, such as CEP290, to centrosomes. Interestingly, knockdown of mindbomb 1 (MIB1), a ubiquitin ligase that promotes PCM1 ubiquitylation and degradation, in USP9X-depleted cells largely restores PCM1 protein levels and corrects defects caused by the loss of USP9X. Overall, our study reveals that USP9X is a constituent of centriolar satellites and functions to maintain centriolar satellite integrity by stabilizing PCM1.
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Affiliation(s)
- Ke-Jun Han
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Zhiping Wu
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Chad G Pearson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Junmin Peng
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Kunhua Song
- Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Chang-Wei Liu
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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11
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Custer SK, Foster JN, Astroski JW, Androphy EJ. Abnormal Golgi morphology and decreased COPI function in cells with low levels of SMN. Brain Res 2018; 1706:135-146. [PMID: 30408476 DOI: 10.1016/j.brainres.2018.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 11/02/2018] [Accepted: 11/03/2018] [Indexed: 12/13/2022]
Abstract
We report here the finding of abnormal Golgi apparatus morphology in motor neuron like cells depleted of SMN as well as Golgi apparatus morphology in SMA patient fibroblasts. Rescue experiments demonstrate that this abnormality is dependent on SMN, but can also be rescued by expression of the COPI coatomer subunit alpha-COP. A motor neuron-like cell line containing an inducible alpha-COP shRNA was created to generate a parallel system to study knockdown of SMN or alpha-COP. Multiple assays of COPI-dependent intracellular trafficking in cells depleted of SMN demonstrate that alpha-COP function is suboptimal, including failed sequestration of plasma membrane proteins, altered binding of mRNA, and defective targeting and transport of Golgi-resident proteins.
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Affiliation(s)
- S K Custer
- Walther Hall, R3 C636, 980 West Walnut Street, Indianapolis, IN 46202, United States.
| | - J N Foster
- Walther Hall, R3 C636, 980 West Walnut Street, Indianapolis, IN 46202, United States.
| | - J W Astroski
- Walther Hall, R3 C636, 980 West Walnut Street, Indianapolis, IN 46202, United States.
| | - E J Androphy
- Walther Hall, R3 C636, 980 West Walnut Street, Indianapolis, IN 46202, United States.
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12
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Chaytow H, Huang YT, Gillingwater TH, Faller KME. The role of survival motor neuron protein (SMN) in protein homeostasis. Cell Mol Life Sci 2018; 75:3877-3894. [PMID: 29872871 PMCID: PMC6182345 DOI: 10.1007/s00018-018-2849-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 12/11/2022]
Abstract
Ever since loss of survival motor neuron (SMN) protein was identified as the direct cause of the childhood inherited neurodegenerative disorder spinal muscular atrophy, significant efforts have been made to reveal the molecular functions of this ubiquitously expressed protein. Resulting research demonstrated that SMN plays important roles in multiple fundamental cellular homeostatic pathways, including a well-characterised role in the assembly of the spliceosome and biogenesis of ribonucleoproteins. More recent studies have shown that SMN is also involved in other housekeeping processes, including mRNA trafficking and local translation, cytoskeletal dynamics, endocytosis and autophagy. Moreover, SMN has been shown to influence mitochondria and bioenergetic pathways as well as regulate function of the ubiquitin-proteasome system. In this review, we summarise these diverse functions of SMN, confirming its key role in maintenance of the homeostatic environment of the cell.
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Affiliation(s)
- Helena Chaytow
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Yu-Ting Huang
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
| | - Kiterie M E Faller
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
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13
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Lafarga V, Tapia O, Sharma S, Bengoechea R, Stoecklin G, Lafarga M, Berciano MT. CBP-mediated SMN acetylation modulates Cajal body biogenesis and the cytoplasmic targeting of SMN. Cell Mol Life Sci 2018; 75:527-546. [PMID: 28879433 PMCID: PMC11105684 DOI: 10.1007/s00018-017-2638-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/09/2017] [Accepted: 08/29/2017] [Indexed: 01/12/2023]
Abstract
The survival of motor neuron (SMN) protein plays an essential role in the biogenesis of spliceosomal snRNPs and the molecular assembly of Cajal bodies (CBs). Deletion of or mutations in the SMN1 gene cause spinal muscular atrophy (SMA) with degeneration and loss of motor neurons. Reduced SMN levels in SMA lead to deficient snRNP biogenesis with consequent splicing pathology. Here, we demonstrate that SMN is a novel and specific target of the acetyltransferase CBP (CREB-binding protein). Furthermore, we identify lysine (K) 119 as the main acetylation site in SMN. Importantly, SMN acetylation enhances its cytoplasmic localization, causes depletion of CBs, and reduces the accumulation of snRNPs in nuclear speckles. In contrast, the acetylation-deficient SMNK119R mutant promotes formation of CBs and a novel category of promyelocytic leukemia (PML) bodies enriched in this protein. Acetylation increases the half-life of SMN protein, reduces its cytoplasmic diffusion rate and modifies its interactome. Hence, SMN acetylation leads to its dysfunction, which explains the ineffectiveness of HDAC (histone deacetylases) inhibitors in SMA therapy despite their potential to increase SMN levels.
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Affiliation(s)
- Vanesa Lafarga
- Laboratory of Genomic Instability, "Centro Nacional de Investigaciones Oncológicas" (CNIO), 28024, Madrid, Spain
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120, Heidelberg, Germany
| | - Olga Tapia
- Department of Anatomy and Cell Biology, "Centro de Investigación en Red de Enfermedades Neurodegenerativas" (CIBERNED), University of Cantabria-IDIVAL, 39011, Santander, Spain
| | - Sahil Sharma
- Department of Biochemistry, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, 68167, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), 68167, Mannheim, Germany
- German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 68167, Mannheim, Germany
| | - Rocio Bengoechea
- Department of Neurology, The Hope Center for Neurological Diseases, School of Medicine of Washington University, St. Louis, 63110, USA
| | - Georg Stoecklin
- Department of Biochemistry, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, 68167, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), 68167, Mannheim, Germany
- German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 68167, Mannheim, Germany
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology, "Centro de Investigación en Red de Enfermedades Neurodegenerativas" (CIBERNED), University of Cantabria-IDIVAL, 39011, Santander, Spain
| | - Maria T Berciano
- Department of Anatomy and Cell Biology, "Centro de Investigación en Red de Enfermedades Neurodegenerativas" (CIBERNED), University of Cantabria-IDIVAL, 39011, Santander, Spain.
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14
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Gray KM, Kaifer KA, Baillat D, Wen Y, Bonacci TR, Ebert AD, Raimer AC, Spring AM, Have ST, Glascock JJ, Gupta K, Van Duyne GD, Emanuele MJ, Lamond AI, Wagner EJ, Lorson CL, Matera AG. Self-oligomerization regulates stability of survival motor neuron protein isoforms by sequestering an SCF Slmb degron. Mol Biol Cell 2018; 29:96-110. [PMID: 29167380 PMCID: PMC5909936 DOI: 10.1091/mbc.e17-11-0627] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 11/14/2017] [Indexed: 12/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by homozygous mutations in human SMN1 Expression of a duplicate gene (SMN2) primarily results in skipping of exon 7 and production of an unstable protein isoform, SMNΔ7. Although SMN2 exon skipping is the principal contributor to SMA severity, mechanisms governing stability of survival motor neuron (SMN) isoforms are poorly understood. We used a Drosophila model system and label-free proteomics to identify the SCFSlmb ubiquitin E3 ligase complex as a novel SMN binding partner. SCFSlmb interacts with a phosphor degron embedded within the human and fruitfly SMN YG-box oligomerization domains. Substitution of a conserved serine (S270A) interferes with SCFSlmb binding and stabilizes SMNΔ7. SMA-causing missense mutations that block multimerization of full-length SMN are also stabilized in the degron mutant background. Overexpression of SMNΔ7S270A, but not wild-type (WT) SMNΔ7, provides a protective effect in SMA model mice and human motor neuron cell culture systems. Our findings support a model wherein the degron is exposed when SMN is monomeric and sequestered when SMN forms higher-order multimers.
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Affiliation(s)
- Kelsey M Gray
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Kevin A Kaifer
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - David Baillat
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550
| | - Ying Wen
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Thomas R Bonacci
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Amanda C Raimer
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Ashlyn M Spring
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Sara Ten Have
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD15EH, UK
| | - Jacqueline J Glascock
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Gregory D Van Duyne
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Michael J Emanuele
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Angus I Lamond
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD15EH, UK
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550
| | - Christian L Lorson
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
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15
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Lysine-Less Variants of Spinal Muscular Atrophy SMN and SMNΔ7 Proteins Are Degraded by the Proteasome Pathway. Int J Mol Sci 2017; 18:ijms18122667. [PMID: 29292768 PMCID: PMC5751269 DOI: 10.3390/ijms18122667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 11/30/2017] [Accepted: 12/04/2017] [Indexed: 11/17/2022] Open
Abstract
Spinal muscular atrophy is due to mutations affecting the SMN1 gene coding for the full-length protein (survival motor neuron; SMN) and the SMN2 gene that preferentially generates an exon 7-deleted protein (SMNΔ7) by alternative splicing. To study SMN and SMNΔ7 degradation in the cell, we have used tagged versions at the N- (Flag) or C-terminus (V5) of both proteins. Transfection of those constructs into HeLa cells and treatment with cycloheximide showed that those protein constructs were degraded. Proteasomal degradation usually requires prior lysine ubiquitylation. Surprisingly, lysine-less variants of both proteins tagged either at N- (Flag) or C-terminus (V5) were also degraded. The degradation of the endogenous SMN protein, and the protein constructs mentioned above, was mediated by the proteasome, as it was blocked by lactacystin, a specific and irreversible proteasomal inhibitor. The results obtained allowed us to conclude that SMN and SMNΔ7 proteasomal degradation did not absolutely require internal ubiquitylation nor N-terminal ubiquitylation (prevented by N-terminal tagging). While the above conclusions are firmly supported by the experimental data presented, we discuss and justify the need of deep proteomic techniques for the study of SMN complex components (orphan and bound) turn-over to understand the physiological relevant mechanisms of degradation of SMN and SMNΔ7 in the cell.
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16
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Raimer AC, Gray KM, Matera AG. SMN - A chaperone for nuclear RNP social occasions? RNA Biol 2017; 14:701-711. [PMID: 27648855 PMCID: PMC5519234 DOI: 10.1080/15476286.2016.1236168] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 12/24/2022] Open
Abstract
Survival Motor Neuron (SMN) protein localizes to both the nucleus and the cytoplasm. Cytoplasmic SMN is diffusely localized in large oligomeric complexes with core member proteins, called Gemins. Biochemical and cell biological studies have demonstrated that the SMN complex is required for the cytoplasmic assembly and nuclear transport of Sm-class ribonucleoproteins (RNPs). Nuclear SMN accumulates with spliceosomal small nuclear (sn)RNPs in Cajal bodies, sub-domains involved in multiple facets of snRNP maturation. Thus, the SMN complex forms stable associations with both nuclear and cytoplasmic snRNPs, and plays a critical role in their biogenesis. In this review, we focus on potential functions of the nuclear SMN complex, with particular emphasis on its role within the Cajal body.
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Affiliation(s)
- Amanda C. Raimer
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kelsey M. Gray
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - A. Gregory Matera
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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17
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Sawyer IA, Hager GL, Dundr M. Specific genomic cues regulate Cajal body assembly. RNA Biol 2017; 14:791-803. [PMID: 27715441 PMCID: PMC5519236 DOI: 10.1080/15476286.2016.1243648] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/06/2016] [Accepted: 09/27/2016] [Indexed: 02/07/2023] Open
Abstract
The assembly of specialized sub-nuclear microenvironments known as nuclear bodies (NBs) is important for promoting efficient nuclear function. In particular, the Cajal body (CB), a prominent NB that facilitates spliceosomal snRNP biogenesis, assembles in response to genomic cues. Here, we detail the factors that regulate CB assembly and structural maintenance. These include the importance of transcription at nucleating gene loci, the grouping of these genes on human chromosomes 1, 6 and 17, as well as cell cycle and biochemical regulation of CB protein function. We also speculate on the correlation between CB formation and RNA splicing levels in neurons and cancer. The timing and location of these specific molecular events is critical to CB assembly and its contribution to genome function. However, further work is required to explore the emerging biophysical characteristics of CB assembly and the impact upon subsequent genome reorganization.
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Affiliation(s)
- Iain A. Sawyer
- Department of Cell Biology, Rosalind Franklin University of Medicine & Science, Chicago Medical School, North Chicago, IL, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Miroslav Dundr
- Department of Cell Biology, Rosalind Franklin University of Medicine & Science, Chicago Medical School, North Chicago, IL, USA
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18
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Hebert MD, Poole AR. Towards an understanding of regulating Cajal body activity by protein modification. RNA Biol 2016; 14:761-778. [PMID: 27819531 DOI: 10.1080/15476286.2016.1243649] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The biogenesis of small nuclear ribonucleoproteins (snRNPs), small Cajal body-specific RNPs (scaRNPs), small nucleolar RNPs (snoRNPs) and the telomerase RNP involves Cajal bodies (CBs). Although many components enriched in the CB contain post-translational modifications (PTMs), little is known about how these modifications impact individual protein function within the CB and, in concert with other modified factors, collectively regulate CB activity. Since all components of the CB also reside in other cellular locations, it is also important that we understand how PTMs affect the subcellular localization of CB components. In this review, we explore the current knowledge of PTMs on the activity of proteins known to enrich in CBs in an effort to highlight current progress as well as illuminate paths for future investigation.
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Affiliation(s)
- Michael D Hebert
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Aaron R Poole
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
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