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Rim C, You MJ, Nahm M, Kwon MS. Emerging role of senescent microglia in brain aging-related neurodegenerative diseases. Transl Neurodegener 2024; 13:10. [PMID: 38378788 PMCID: PMC10877780 DOI: 10.1186/s40035-024-00402-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 01/31/2024] [Indexed: 02/22/2024] Open
Abstract
Brain aging is a recognized risk factor for neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), but the intricate interplay between brain aging and the pathogenesis of these conditions remains inadequately understood. Cellular senescence is considered to contribute to cellular dysfunction and inflammaging. According to the threshold theory of senescent cell accumulation, the vulnerability to neurodegenerative diseases is associated with the rates of senescent cell generation and clearance within the brain. Given the role of microglia in eliminating senescent cells, the accumulation of senescent microglia may lead to the acceleration of brain aging, contributing to inflammaging and increased vulnerability to neurodegenerative diseases. In this review, we propose the idea that the senescence of microglia, which is notably vulnerable to aging, could potentially serve as a central catalyst in the progression of neurodegenerative diseases. The senescent microglia are emerging as a promising target for mitigating neurodegenerative diseases.
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Affiliation(s)
- Chan Rim
- Department of Pharmacology, Research Institute for Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Republic of Korea
| | - Min-Jung You
- Department of Pharmacology, Research Institute for Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Republic of Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Min-Soo Kwon
- Department of Pharmacology, Research Institute for Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Republic of Korea.
- Brainimmunex Inc., 26 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 13522, Republic of Korea.
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Sung W, Noh MY, Nahm M, Kim YS, Ki CS, Kim YE, Kim HJ, Kim SH. Progranulin haploinsufficiency mediates cytoplasmic TDP-43 aggregation with lysosomal abnormalities in human microglia. J Neuroinflammation 2024; 21:47. [PMID: 38347588 PMCID: PMC10863104 DOI: 10.1186/s12974-024-03039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/07/2024] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND Progranulin (PGRN) haploinsufficiency due to progranulin gene (GRN) variants can cause frontotemporal dementia (FTD) with aberrant TAR DNA-binding protein 43 (TDP-43) accumulation. Despite microglial burden with TDP-43-related pathophysiology, direct microglial TDP-43 pathology has not been clarified yet, only emphasized in neuronal pathology. Thus, the objective of this study was to investigate TDP-43 pathology in microglia of patients with PGRN haploinsufficiency. METHODS To design a human microglial cell model with PGRN haploinsufficiency, monocyte-derived microglia (iMGs) were generated from FTD-GRN patients carrying pathogenic or likely pathogenic variants (p.M1? and p.W147*) and three healthy controls. RESULTS iMGs from FTD-GRN patients with PGRN deficiency exhibited severe neuroinflammation phenotype and failure to maintain their homeostatic molecular signatures, along with impaired phagocytosis. In FTD-GRN patients-derived iMGs, significant cytoplasmic TDP-43 aggregation and accumulation of lipid droplets with profound lysosomal abnormalities were observed. These pathomechanisms were mediated by complement C1q activation and upregulation of pro-inflammatory cytokines. CONCLUSIONS Our study provides considerable cellular and molecular evidence that loss-of-function variants of GRN in human microglia can cause microglial dysfunction with abnormal TDP-43 aggregation induced by inflammatory milieu as well as the impaired lysosome. Elucidating the role of microglial TDP-43 pathology in intensifying neuroinflammation in individuals with FTD due to PGRN deficiency and examining consequential effects on microglial dysfunction might yield novel insights into the mechanisms underlying FTD and neurodegenerative disorders.
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Affiliation(s)
- Wonjae Sung
- Department of Neurology, College of Medicine, Hanyang University, 222, Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea
| | - Min-Young Noh
- Department of Neurology, College of Medicine, Hanyang University, 222, Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Yong Sung Kim
- Department of Neurology, College of Medicine, Hanyang University, 222, Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea
| | | | - Young-Eun Kim
- Department of Laboratory Medicine, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Hee-Jin Kim
- Department of Neurology, College of Medicine, Hanyang University, 222, Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea
| | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, 222, Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea.
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Jeon H, Jang SY, Kwak G, Yi YW, You MH, Park NY, Jo JH, Yang JW, Jang HJ, Jeong SY, Moon SK, Doo HM, Nahm M, Kim D, Chang JW, Choi BO, Hong YB. TGFβ4 alleviates the phenotype of Charcot-Marie-Tooth disease type 1A. Brain 2023; 146:3608-3615. [PMID: 37143322 DOI: 10.1093/brain/awad147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 03/30/2023] [Accepted: 04/14/2023] [Indexed: 05/06/2023] Open
Abstract
The duplication of the peripheral myelin protein 22 (PMP22) gene causes a demyelinating type of neuropathy, commonly known as Charcot-Marie-Tooth disease type 1A (CMT1A). Development of effective drugs for CMT1A still remains as an unmet medical need. In the present study, we assessed the role of the transforming growth factor beta 4 (TGFβ4)/Nodal axis in the pathogenesis of CMT1A. First, we identified PMP22 overexpression-induced Nodal expression in Schwann cells, which might be one of the downstream effectors in CMT1A. Administration of Nodal protein at the developmental stage of peripheral nerves induced the demyelinating phenotype in vivo. Second, we further isolated TGFβ4 as an antagonist that could abolish Nodal-induced demyelination. Finally, we developed a recombinant TGFβ4-fragment crystallizable (Fc) fusion protein, CX201, and demonstrated that its application had promyelinating efficacy in Schwann cells. CX201 administration improved the demyelinating phenotypes of CMT1A mouse models at both pre-symptomatic and post-symptomatic stages. These results suggest that the TGFβ4/Nodal axis plays a crucial role in the pathogenesis of CMT1A and might be a potential therapeutic target for CMT1A.
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Affiliation(s)
- Hyeonjin Jeon
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
- Dementia Research Group, Korea Brain Research Institute, Daegu 41062, Korea
| | - So Young Jang
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
| | - Geon Kwak
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351, Korea
- BioMedicine Lab., CKD Research Institute, ChongKunDang Pharm., Yongin 16995, Korea
| | - Yong Weon Yi
- Department of Biochemistry, College of Medicine, Dankook University, Cheonan 31116, Korea
| | - Mi-Hyeon You
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea
| | - Na Young Park
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
| | - Ju Hee Jo
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
| | - Ji Won Yang
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
| | - Hye Ji Jang
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
| | - Sun-Young Jeong
- BioMedicine Lab., CKD Research Institute, ChongKunDang Pharm., Yongin 16995, Korea
| | - Seung Kee Moon
- BioMedicine Lab., CKD Research Institute, ChongKunDang Pharm., Yongin 16995, Korea
| | - Hyun Myung Doo
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351, Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu 41062, Korea
| | - Donghoon Kim
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
- Department of Pharmacology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Jong Wook Chang
- Stem Cell and Regenerative Medicine Institute, Samsung Medical Center, Seoul 06351, Korea
| | - Byung-Ok Choi
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351, Korea
- Stem Cell and Regenerative Medicine Institute, Samsung Medical Center, Seoul 06351, Korea
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Young Bin Hong
- Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan 49201, Korea
- Department of Biochemistry, College of Medicine, Dong-A University, Busan 49201, Korea
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Noh MY, Kwon MS, Oh KW, Nahm M, Park J, Kim YE, Ki CS, Jin HK, Bae JS, Kim SH. Role of NCKAP1 in the Defective Phagocytic Function of Microglia-Like Cells Derived from Rapidly Progressing Sporadic ALS. Mol Neurobiol 2023; 60:4761-4777. [PMID: 37154887 PMCID: PMC10293423 DOI: 10.1007/s12035-023-03339-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 04/04/2023] [Indexed: 05/10/2023]
Abstract
Microglia plays a key role in determining the progression of amyotrophic lateral sclerosis (ALS), yet their precise role in ALS has not been identified in humans. This study aimed to identify a key factor related to the functional characteristics of microglia in rapidly progressing sporadic ALS patients using the induced microglia model, although it is not identical to brain resident microglia. After confirming that microglia-like cells (iMGs) induced by human monocytes could recapitulate the main signatures of brain microglia, step-by-step comparative studies were conducted to delineate functional differences using iMGs from patients with slowly progressive ALS [ALS(S), n = 14] versus rapidly progressive ALS [ALS(R), n = 15]. Despite an absence of significant differences in the expression of microglial homeostatic genes, ALS(R)-iMGs preferentially showed defective phagocytosis and an exaggerated pro-inflammatory response to LPS stimuli compared to ALS(S)-iMGs. Transcriptome analysis revealed that the perturbed phagocytosis seen in ALS(R)-iMGs was closely associated with decreased NCKAP1 (NCK-associated protein 1)-mediated abnormal actin polymerization. NCKAP1 overexpression was sufficient to rescue impaired phagocytosis in ALS(R)-iMGs. Post-hoc analysis indicated that decreased NCKAP1 expression in iMGs was correlated with the progression of ALS. Our data suggest that microglial NCKAP1 may be an alternative therapeutic target in rapidly progressive sporadic ALS.
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Affiliation(s)
- Min-Young Noh
- Department of Neurology, College of Medicine, Hanyang University, Wangsimniro 222-1, Seoul, 04763 Republic of Korea
| | - Min-Soo Kwon
- Department of Pharmacology, Research Institute of Basic Medical Science, School of Medicine, CHA University, CHA Bio Complex, 335 Pangyo, Gyeonggi-Do 13488 Republic of Korea
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Wangsimniro 222-1, Seoul, 04763 Republic of Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Jinseok Park
- Department of Neurology, College of Medicine, Hanyang University, Wangsimniro 222-1, Seoul, 04763 Republic of Korea
| | - Young-Eun Kim
- Department of Laboratory Medicine, College of Medicine, Hanyang University, Wangsimniro 222-1, Seoul, 04763 Republic of Korea
| | - Chang-Seok Ki
- GC Genome Corporation, Yongin, 16924 Republic of Korea
| | - Hee Kyung Jin
- KNU Alzheimer’s Disease Research Institute, Kyungpook National University, Daegu, 41566 Republic of Korea
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Kyungpook National University, Daegu, 41566 Republic of Korea
| | - Jae-sung Bae
- KNU Alzheimer’s Disease Research Institute, Kyungpook National University, Daegu, 41566 Republic of Korea
- Department of Physiology, Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu, 41944 Republic of Korea
- Department of Biomedical Science, BK21 Plus KNU Biomedical Convergence Program, Kyungpook National University, Wangsimniro 222-1, Daegu, 41944 Republic of Korea
| | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Wangsimniro 222-1, Seoul, 04763 Republic of Korea
- Cell Therapy Center, Hanyang University Hospital, Wangsimniro 222-1, Seoul, 04763 Republic of Korea
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Lim SM, Nahm M, Kim SH. Proteostasis and Ribostasis Impairment as Common Cell Death Mechanisms in Neurodegenerative Diseases. J Clin Neurol 2023; 19:101-114. [PMID: 36854331 PMCID: PMC9982182 DOI: 10.3988/jcn.2022.0379] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 12/07/2022] [Accepted: 12/07/2022] [Indexed: 03/02/2023] Open
Abstract
The cellular homeostasis of proteins (proteostasis) and RNA metabolism (ribostasis) are essential for maintaining both the structure and function of the brain. However, aging, cellular stress conditions, and genetic contributions cause disturbances in proteostasis and ribostasis that lead to protein misfolding, insoluble aggregate deposition, and abnormal ribonucleoprotein granule dynamics. In addition to neurons being primarily postmitotic, nondividing cells, they are more susceptible to the persistent accumulation of abnormal aggregates. Indeed, defects associated with the failure to maintain proteostasis and ribostasis are common pathogenic components of age-related neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Furthermore, the neuronal deposition of misfolded and aggregated proteins can cause both increased toxicity and impaired physiological function, which lead to neuronal dysfunction and cell death. There is recent evidence that irreversible liquid-liquid phase separation (LLPS) is responsible for the pathogenic aggregate formation of disease-related proteins, including tau, α-synuclein, and RNA-binding proteins, including transactive response DNA-binding protein 43, fused in sarcoma, and heterogeneous nuclear ribonucleoprotein A1. Investigations of LLPS and its control therefore suggest that chaperone/disaggregase, which reverse protein aggregation, are valuable therapeutic targets for effective treatments for neurological diseases. Here we review and discuss recent studies to highlight the importance of understanding the common cell death mechanisms of proteostasis and ribostasis in neurodegenerative diseases.
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Affiliation(s)
- Su Min Lim
- Cell Therapy Center and Department of Neurology, College of Medicine, Hanyang University, Seoul, Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu, Korea
| | - Seung Hyun Kim
- Cell Therapy Center and Department of Neurology, College of Medicine, Hanyang University, Seoul, Korea.
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6
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Sung W, Nahm M, Lim SM, Noh MY, Lee S, Hwang SM, Kim YH, Park J, Oh KW, Ki CS, Kim YE, Kim SH. Clinical and genetic characteristics of amyotrophic lateral sclerosis patients with ANXA11 variants. Brain Commun 2022; 4:fcac299. [PMID: 36458208 PMCID: PMC9707645 DOI: 10.1093/braincomms/fcac299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/26/2022] [Accepted: 11/16/2022] [Indexed: 08/12/2023] Open
Abstract
Increasing genetic evidence supports the hypothesis that variants in the annexin A11 gene (ANXA11 ) contribute to amyotrophic lateral sclerosis pathogenesis. Therefore, we studied the clinical aspects of sporadic amyotrophic lateral sclerosis patients carrying ANXA11 variants. We also implemented functional experiments to verify the pathogenicity of the hotspot variants associated with amyotrophic lateral sclerosis-frontotemporal dementia. Korean patients diagnosed with amyotrophic lateral sclerosis (n = 882) underwent genetic evaluations through next-generation sequencing, which identified 16 ANXA11 variants in 26 patients. We analysed their clinical features, such as the age of onset, progression rate, initial symptoms and cognitive status. To evaluate the functional significance of the ANXA11 variants in amyotrophic lateral sclerosis-frontotemporal dementia pathology, we additionally utilized patient fibroblasts carrying frontotemporal dementia-linked ANXA11 variants (p.P36R and p.D40G ) to perform a series of in vitro studies, including calcium imaging, stress granule dynamics and protein translation. The frequency of the pathogenic or likely pathogenic variants of ANXA11 was 0.3% and the frequency of variants classified as variants of unknown significance was 2.6%. The patients with variants in the low-complexity domain presented unique clinical features, including late-onset, a high prevalence of amyotrophic lateral sclerosis-frontotemporal dementia, a fast initial progression rate and a high tendency for bulbar-onset compared with patients carrying variants in the C-terminal repeated annexin homology domains. In addition, functional studies using amyotrophic lateral sclerosis-frontotemporal dementia patient fibroblasts revealed that the ANXA11 variants p.P36R and p.D40G impaired intracellular calcium homeostasis, stress granule disassembly and protein translation. This study suggests that the clinical manifestations of amyotrophic lateral sclerosis and amyotrophic lateral sclerosis-frontotemporal dementia spectrum patients with ANXA11 variants could be distinctively characterized depending upon the location of the variant.
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Affiliation(s)
- Wonjae Sung
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Su Min Lim
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Min-Young Noh
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Sanggon Lee
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Sung-Min Hwang
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon, Republic of Korea
| | - Yong Ho Kim
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon, Republic of Korea
| | - Jinseok Park
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | | | - Young-Eun Kim
- Department of Laboratory Medicine, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
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7
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Park J, Kim Y, Oh K, Nahm M, Kim YJ, Kim MJ, Kim SH. Gelsolin variant amyloidosis mimicking progressive bulbar palsy. Muscle Nerve 2022; 66:E28-E30. [PMID: 36047766 PMCID: PMC9826199 DOI: 10.1002/mus.27714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 01/11/2023]
Affiliation(s)
- Jinseok Park
- Department of NeurologyCollege of Medicine, Hanyang UniversitySeoulSouth Korea,Cell Therapy CenterHanyang University HospitalSeoulSouth Korea
| | - Young‐Eun Kim
- Department of Laboratory MedicineCollege of Medicine, Hanyang UniversitySeoulSouth Korea
| | - Ki‐Wook Oh
- Department of NeurologyCollege of Medicine, Hanyang UniversitySeoulSouth Korea,Cell Therapy CenterHanyang University HospitalSeoulSouth Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research InstituteDaeguSouth Korea
| | - Yu Jeong Kim
- Department of OphthalmologyHanyang University College of MedicineSeoulSouth Korea
| | - Mi Jung Kim
- Department of Rehabilitation MedicineHanyang University College of MedicineSeoulSouth Korea
| | - Seung Hyun Kim
- Department of NeurologyCollege of Medicine, Hanyang UniversitySeoulSouth Korea,Cell Therapy CenterHanyang University HospitalSeoulSouth Korea
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8
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Cha SJ, Lee S, Choi HJ, Han YJ, Jeon YM, Jo M, Lee S, Nahm M, Lim SM, Kim SH, Kim HJ, Kim K. Therapeutic modulation of GSTO activity rescues FUS-associated neurotoxicity via deglutathionylation in ALS disease models. Dev Cell 2022; 57:783-798.e8. [PMID: 35320731 DOI: 10.1016/j.devcel.2022.02.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/25/2021] [Accepted: 02/23/2022] [Indexed: 11/28/2022]
Abstract
Fused in sarcoma (FUS) is a DNA/RNA-binding protein that is involved in DNA repair and RNA processing. FUS is associated with neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the molecular mechanisms underlying FUS-mediated neurodegeneration are largely unknown. Here, using a Drosophila model, we showed that the overexpression of glutathione transferase omega 2 (GstO2) reduces cytoplasmic FUS aggregates and prevents neurodegenerative phenotypes, including neurotoxicity and mitochondrial dysfunction. We found a FUS glutathionylation site at the 447th cysteine residue in the RanBP2-type ZnF domain. The glutathionylation of FUS induces FUS aggregation by promoting phase separation. GstO2 reduced cytoplasmic FUS aggregation by deglutathionylation in Drosophila brains. Moreover, we demonstrated that the overexpression of human GSTO1, the homolog of Drosophila GstO2, attenuates FUS-induced neurotoxicity and cytoplasmic FUS accumulation in mouse neuronal cells. Thus, the modulation of FUS glutathionylation might be a promising therapeutic strategy for FUS-associated neurodegenerative diseases.
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Affiliation(s)
- Sun Joo Cha
- Department of Medical Science, Soonchunhyang University, Asan 31538, Korea
| | - Seongsoo Lee
- Gwangju Center, Korea Basic Science Institute (KBSI), Gwangju 61186, Korea
| | - Hyun-Jun Choi
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan 31151, Korea
| | - Yeo Jeong Han
- Department of Medical Science, Soonchunhyang University, Asan 31538, Korea
| | - Yu-Mi Jeon
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu 41068, Korea
| | - Myungjin Jo
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu 41068, Korea
| | - Shinrye Lee
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu 41068, Korea
| | - Minyeop Nahm
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu 41068, Korea
| | - Su Min Lim
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea; Medical Research Institute, Hanyang University, Seoul 04763, Korea
| | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea; Medical Research Institute, Hanyang University, Seoul 04763, Korea
| | - Hyung-Jun Kim
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu 41068, Korea.
| | - Kiyoung Kim
- Department of Medical Science, Soonchunhyang University, Asan 31538, Korea.
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9
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Nahm M, Lim SM, Kim YE, Park J, Noh MY, Lee S, Roh JE, Hwang SM, Park CK, Kim YH, Lim G, Lee J, Oh KW, Ki CS, Kim SH. ANXA11 mutations in ALS cause dysregulation of calcium homeostasis and stress granule dynamics. Sci Transl Med 2021; 12:12/566/eaax3993. [PMID: 33087501 DOI: 10.1126/scitranslmed.aax3993] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 12/15/2019] [Accepted: 07/04/2020] [Indexed: 12/14/2022]
Abstract
Dysregulation of calcium ion homeostasis and abnormal protein aggregation have been proposed as major pathogenic hallmarks underpinning selective degeneration of motor neurons in amyotrophic lateral sclerosis (ALS). Recently, mutations in annexin A11 (ANXA11), a gene encoding a Ca2+-dependent phospholipid-binding protein, have been identified in familial and sporadic ALS. However, the physiological and pathophysiological roles of ANXA11 remain unknown. Here, we report functions of ANXA11 related to intracellular Ca2+ homeostasis and stress granule dynamics. We analyzed the exome sequences of 500 Korean patients with sALS and identified nine ANXA11 variants in 13 patients. The amino-terminal variants p.G38R and p.D40G within the low-complexity domain of ANXA11 enhanced aggregation propensity, whereas the carboxyl-terminal ANX domain variants p.H390P and p.R456H altered Ca2+ responses. Furthermore, all four variants in ANXA11 underwent abnormal phase separation to form droplets with aggregates and led to the alteration of the biophysical properties of ANXA11. These functional defects caused by ALS-linked variants induced alterations in both intracellular Ca2+ homeostasis and stress granule disassembly. We also revealed that p.G228Lfs*29 reduced ANXA11 expression and impaired Ca2+ homeostasis, as caused by missense variants. Ca2+-dependent interaction and coaggregation between ANXA11 and ALS-causative RNA-binding proteins, FUS and hnRNPA1, were observed in motor neuron cells and brain from a patient with ALS-FUS. The expression of ALS-linked ANXA11 variants in motor neuron cells caused cytoplasmic sequestration of endogenous FUS and triggered neuronal apoptosis. Together, our findings suggest that disease-associated ANXA11 mutations can contribute to ALS pathogenesis through toxic gain-of-function mechanisms involving abnormal protein aggregation.
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Affiliation(s)
- Minyeop Nahm
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea.,Biomedical Research Institute, Hanyang University, Seoul 04763, Korea
| | - Su Min Lim
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea.,Biomedical Research Institute, Hanyang University, Seoul 04763, Korea
| | - Young-Eun Kim
- Department of Laboratory Medicine, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Jinseok Park
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Min-Young Noh
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea.,Biomedical Research Institute, Hanyang University, Seoul 04763, Korea
| | - Sanggon Lee
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Ju Eun Roh
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 21999, Korea
| | - Sung-Min Hwang
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 21999, Korea
| | - Chul-Kyu Park
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 21999, Korea
| | - Yong Ho Kim
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 21999, Korea
| | - GyuTae Lim
- Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea.,Department of Bioinformatics, KRIBB School of Bioscience, University of Science and Technology (UST), Daejeon 34113, Korea
| | - Jinhyuk Lee
- Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea.,Department of Bioinformatics, KRIBB School of Bioscience, University of Science and Technology (UST), Daejeon 34113, Korea
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | | | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea. .,Biomedical Research Institute, Hanyang University, Seoul 04763, Korea
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10
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Kim J, Kim S, Nahm M, Li TN, Lin HC, Kim YD, Lee J, Yao CK, Lee S. ALS2 regulates endosomal trafficking, postsynaptic development, and neuronal survival. J Cell Biol 2021; 220:e202007112. [PMID: 33683284 PMCID: PMC7944400 DOI: 10.1083/jcb.202007112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 01/07/2021] [Accepted: 02/11/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in the human ALS2 gene cause recessive juvenile-onset amyotrophic lateral sclerosis and related motor neuron diseases. Although the ALS2 protein has been identified as a guanine-nucleotide exchange factor for the small GTPase Rab5, its physiological roles remain largely unknown. Here, we demonstrate that the Drosophila homologue of ALS2 (dALS2) promotes postsynaptic development by activating the Frizzled nuclear import (FNI) pathway. dALS2 loss causes structural defects in the postsynaptic subsynaptic reticulum (SSR), recapitulating the phenotypes observed in FNI pathway mutants. Consistently, these developmental phenotypes are rescued by postsynaptic expression of the signaling-competent C-terminal fragment of Drosophila Frizzled-2 (dFz2). We further demonstrate that dALS2 directs early to late endosome trafficking and that the dFz2 C terminus is cleaved in late endosomes. Finally, dALS2 loss causes age-dependent progressive defects resembling ALS, including locomotor impairment and brain neurodegeneration, independently of the FNI pathway. These findings establish novel regulatory roles for dALS2 in endosomal trafficking, synaptic development, and neuronal survival.
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Affiliation(s)
- Joohyung Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Sungdae Kim
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Minyeop Nahm
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Tsai-Ning Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsin-Chieh Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yeongjin David Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
| | - Jihye Lee
- Department of Oral Pathology, Department of Life Science in Dentistry, Dental and Life Science Institute, School of Dentistry, Pusan National University, Yangsan, Korea
| | - Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
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11
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Lim SM, Kim YE, Park J, Nahm M, Park HC, Ki CS, Oh KW, Kim SH. A novel de novo ATP1A3 mutation in motor neuron disease mimicking rapid onset dystonia parkinsonism. IBRO Rep 2019. [DOI: 10.1016/j.ibror.2019.07.1118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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12
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Nahm M, Lim SM, Noh MY, Oh KW, Ki CS, Kim SH. ANXA11 mutations in ALS cause dysregulation of calcium homeostasis and stress granule dynamics. IBRO Rep 2019. [DOI: 10.1016/j.ibror.2019.07.1124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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13
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Heo K, Lim SM, Nahm M, Kim YE, Oh KW, Park HT, Ki CS, Kim SH, Lee S. A De Novo RAPGEF2 Variant Identified in a Sporadic Amyotrophic Lateral Sclerosis Patient Impairs Microtubule Stability and Axonal Mitochondria Distribution. Exp Neurobiol 2018; 27:550-563. [PMID: 30636905 PMCID: PMC6318558 DOI: 10.5607/en.2018.27.6.550] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 11/24/2018] [Accepted: 11/26/2018] [Indexed: 12/23/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that is frequently linked to microtubule abnormalities and mitochondrial trafficking defects. Whole exome sequencing (WES) of patient-parent trios has proven to be an efficient strategy for identifying rare de novo genetic variants responsible for sporadic ALS (sALS). Using a trio-WES approach, we identified a de novo RAPGEF2 variant (c.4069G>A, p.E1357K) in a patient with early-onset sALS. To assess the pathogenic effects of this variant, we have used patient-derived skin fibroblasts and motor neuron-specific overexpression of the RAPGEF2-E1357K mutant protein in Drosophila. Patient fibroblasts display reduced microtubule stability and defective microtubule network morphology. The intracellular distribution, ultrastructure, and function of mitochondria are also impaired in patient cells. Overexpression of the RAPGEF2 mutant in Drosophila motor neurons reduces the stability of axonal microtubules and disrupts the distribution of mitochondria to distal axons and neuromuscular junction (NMJ) synapses. We also show that the recruitment of the pro-apoptotic protein BCL2-associated X (BAX) to mitochondria is significantly increased in patient fibroblasts compared with control cells. Finally, increasing microtubule stability through pharmacological inhibition of histone deacetylase 6 (HDAC6) rescues defects in the intracellular distribution of mitochondria and BAX. Overall, our data suggest that the RAPGEF2 variant identified in this study can drive ALS-related pathogenic effects through microtubule dysregulation.
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Affiliation(s)
- Keunjung Heo
- Department of Brain and Cognitive Sciences and Dental Research Institute, Seoul National University, Seoul 08826, Korea
| | - Su Min Lim
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Minyeop Nahm
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Young-Eun Kim
- Department of Laboratory Medicine, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Hwan Tae Park
- Department of Molecular Neuroscience, College of Medicine, Dong-A University, Busan 49201, Korea
| | | | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences and Dental Research Institute, Seoul National University, Seoul 08826, Korea
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14
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Lim SM, Choi BO, Oh SI, Choi WJ, Oh KW, Nahm M, Xue Y, Choi JH, Choi JY, Kim YE, Chung KW, Fu XD, Ki CS, Kim SH. Patient fibroblasts-derived induced neurons demonstrate autonomous neuronal defects in adult-onset Krabbe disease. Oncotarget 2018; 7:74496-74509. [PMID: 27780934 PMCID: PMC5342682 DOI: 10.18632/oncotarget.12812] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 10/14/2016] [Indexed: 01/29/2023] Open
Abstract
Krabbe disease (KD) is an autosomal recessive neurodegenerative disorder caused by defective β-galactosylceramidase (GALC), a lysosomal enzyme responsible for cleavage of several key substrates including psychosine. Accumulation of psychosine to the cytotoxic levels in KD patients is thought to cause dysfunctions in myelinating glial cells based on a comprehensive study of demyelination in KD. However, recent evidence suggests myelin-independent neuronal death in the murine model of KD, thus indicating defective GALC in neurons as an autonomous mechanism for neuronal cell death in KD. These observations prompted us to generate induced neurons (iNeurons) from two adult-onset KD patients carrying compound heterozygous mutations (p.[K563*];[L634S]) and (p.[N228_S232delinsTP];[G286D]) to determine the direct contribution of autonomous neuronal toxicity to KD. Here we report that directly converted KD iNeurons showed not only diminished GALC activity and increased psychosine levels, as expected, but also neurite fragmentation and abnormal neuritic branching. The lysosomal-associated membrane proteins 1 (LAMP1) was expressed at higher levels than controls, LAMP1-positive vesicles were significantly enlarged and fragmented, and mitochondrial morphology and its function were altered in KD iNeurons. Strikingly, we demonstrated that psychosine was sufficient to induce neurite defects, mitochondrial fragmentation, and lysosomal alterations in iNeurons derived in healthy individuals, thus establishing the causal effect of the cytotoxic GALC substrate in KD and the autonomous neuronal toxicity in KD pathology.
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Affiliation(s)
- Su Min Lim
- Biomedical Research Institute, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Byung-Ok Choi
- Department of Neurology and Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Seong-Il Oh
- Department of Neurology, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Won Jun Choi
- Department of Neurology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates
| | - Ki-Wook Oh
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea.,Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Minyeop Nahm
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Yuanchao Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jae Hyeok Choi
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Ji Young Choi
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | | | - Ki Wha Chung
- Department of Biological Sciences, Gongju National University, Gongju, Republic of Korea
| | - Xiang-Dong Fu
- Department of Cellular Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea.,Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea
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15
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Lim SM, Kim YE, Choi WJ, Oh KW, Noh MY, Kwon MS, Nahm M, Kim N, Ki CS, Kim SH. CLEC4C p.K210del variant causes impaired cell surface transport in plasmacytoid dendritic cells of amyotrophic lateral sclerosis. Oncotarget 2018; 7:24942-9. [PMID: 26943047 PMCID: PMC5041881 DOI: 10.18632/oncotarget.7886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/29/2016] [Indexed: 01/06/2023] Open
Abstract
The type II C-type lectin CLEC4C is a transmembrane protein selectively expressed on plasmacytoid dendritic cells (PDCs). Although its mechanism of action remains unclear, triggering of the extracellular C-terminal C-type carbohydrate recognition region of CLEC4C regulates the secretion of proinflammatory cytokines and type I IFNs in PDCs. Applying whole-exome sequencing in a patient with juvenile amyotrophic lateral sclerosis (ALS) and both healthy parents, we identified a de novo CLEC4C variant (c.629_631delAGA; p.Lys210del). In this study, we report that the deletion of a lysine residue at the extracellular region of CLEC4C yields a C-terminal dilysine motif that results in endoplasmic reticulum (ER) retention of the protein in transfected HeLa and Jurkat T lymphoma cell models. As a consequence, a decrease in the surface expression of CLEC4C and the ER localization of the mutant construct were observed. Furthermore, depletion of the cell surface CLEC4C level was also observed in the patient PDCs, further suggesting that the variant p.Lys210del CLEC4C may contribute to juvenile ALS susceptibility.
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Affiliation(s)
- Su Min Lim
- Department of Translational Medicine, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | | | - Won Jun Choi
- Department of Neurology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Min-Young Noh
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Min-Soo Kwon
- Department of Pharmacology, School of Medicine, CHA University, CHA Bio Complex, Seongnam, Republic of Korea
| | - Minyeop Nahm
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Namshin Kim
- Epigenomics Research Center Genome Institute, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Department of Translational Medicine, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.,Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
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16
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Heo K, Nahm M, Lee MJ, Kim YE, Ki CS, Kim SH, Lee S. The Rap activator Gef26 regulates synaptic growth and neuronal survival via inhibition of BMP signaling. Mol Brain 2017; 10:62. [PMID: 29282074 PMCID: PMC5745669 DOI: 10.1186/s13041-017-0342-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 12/12/2017] [Indexed: 12/24/2022] Open
Abstract
In Drosophila, precise regulation of BMP signaling is essential for normal synaptic growth at the larval neuromuscular junction (NMJ) and neuronal survival in the adult brain. However, the molecular mechanisms underlying fine-tuning of BMP signaling in neurons remain poorly understood. We show that loss of the Drosophila PDZ guanine nucleotide exchange factor Gef26 significantly increases synaptic growth at the NMJ and enhances BMP signaling in motor neurons. We further show that Gef26 functions upstream of Rap1 in motor neurons to restrain synaptic growth. Synaptic overgrowth in gef26 or rap1 mutants requires BMP signaling, indicating that Gef26 and Rap1 regulate synaptic growth via inhibition of BMP signaling. We also show that Gef26 is involved in the endocytic downregulation of surface expression of the BMP receptors thickveins (Tkv) and wishful thinking (Wit). Finally, we demonstrate that loss of Gef26 also induces progressive brain neurodegeneration through Rap1- and BMP signaling-dependent mechanisms. Taken together, these results suggest that the Gef26-Rap1 signaling pathway regulates both synaptic growth and neuronal survival by controlling BMP signaling.
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Affiliation(s)
- Keunjung Heo
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 08826, South Korea.,Department of Cell & Developmental Biology, Dental Research Institute, Seoul National University, Seoul, 03080, South Korea
| | - Minyeop Nahm
- Department of Neurology, Hanyang University College of Medicine, Seoul, 04763, South Korea
| | - Min-Jung Lee
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 08826, South Korea.,Department of Cell & Developmental Biology, Dental Research Institute, Seoul National University, Seoul, 03080, South Korea
| | - Young-Eun Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, South Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, South Korea
| | - Seung Hyun Kim
- Department of Neurology, Hanyang University College of Medicine, Seoul, 04763, South Korea
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 08826, South Korea.
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17
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Kim S, Nahm M, Kim N, Kwon Y, Kim J, Choi S, Choi EY, Shim J, Lee C, Lee S. Graf regulates hematopoiesis through GEEC endocytosis of EGFR. Development 2017; 144:4159-4172. [PMID: 28993397 DOI: 10.1242/dev.153288] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 10/02/2017] [Indexed: 12/24/2022]
Abstract
GTPase regulator associated with focal adhesion kinase 1 (GRAF1) is an essential component of the GPI-enriched endocytic compartment (GEEC) endocytosis pathway. Mutations in the human GRAF1 gene are associated with acute myeloid leukemia, but its normal role in myeloid cell development remains unclear. We show that Graf, the Drosophila ortholog of GRAF1, is expressed and specifically localizes to GEEC endocytic membranes in macrophage-like plasmatocytes. We also find that loss of Graf impairs GEEC endocytosis, enhances EGFR signaling and induces a plasmatocyte overproliferation phenotype that requires the EGFR signaling cascade. Mechanistically, Graf-dependent GEEC endocytosis serves as a major route for EGFR internalization at high, but not low, doses of the predominant Drosophila EGFR ligand Spitz (Spi), and is indispensable for efficient EGFR degradation and signal attenuation. Finally, Graf interacts directly with EGFR in a receptor ubiquitylation-dependent manner, suggesting a mechanism by which Graf promotes GEEC endocytosis of EGFR at high Spi. Based on our findings, we propose a model in which Graf functions to downregulate EGFR signaling by facilitating Spi-induced receptor internalization through GEEC endocytosis, thereby restraining plasmatocyte proliferation.
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Affiliation(s)
- Sungdae Kim
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul 08826, Korea
| | - Minyeop Nahm
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul 08826, Korea
| | - Najin Kim
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul 08826, Korea
| | - Yumi Kwon
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Joohyung Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul 08826, Korea
| | - Sukwoo Choi
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Eun Young Choi
- Department of Biomedical Sciences, Seoul National University, Seoul 08826, Korea
| | - Jiwon Shim
- Department of Life Science, Hanyang University, Seoul 04763, Korea
| | - Cheolju Lee
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Seungbok Lee
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul 08826, Korea .,Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul 08826, Korea.,Department of Brain and Cognitive Sciences, Seoul National University, Seoul 08826, Korea
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18
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Kim YE, Oh KW, Noh MY, Nahm M, Park J, Lim SM, Jang JH, Cho EH, Ki CS, Lee S, Kim SH. Genetic and functional analysis of TBK1 variants in Korean patients with sporadic amyotrophic lateral sclerosis. Neurobiol Aging 2016; 50:170.e1-170.e6. [PMID: 27939697 DOI: 10.1016/j.neurobiolaging.2016.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/11/2016] [Accepted: 11/11/2016] [Indexed: 11/29/2022]
Abstract
The TANK-binding kinase 1 (TBK1) gene has recently been identified as a novel causative gene of amyotrophic lateral sclerosis (ALS). This study aims to determine the frequency and spectrum of TBK1 variants and their functional implications in Korean patients with sporadic ALS (sALS). TBK1 sequences were analyzed in 129 consecutive patients with sALS using either multigene panel or exome sequencing. One frameshift (c.1414delA) and 3 missense variants of uncertain significance in TBK1 were found in 4 patients each. In vitro functional studies revealed that the c.1414delA (p.Ile472Serfs*8) variant was associated with reduced mRNA expression of TBK1. Moreover, protein expression of this variant in patient-derived fibroblasts disrupted binding to autophagy adapter proteins and inhibited the function of TBK1 in HEK293T cells. In contrast, the 3 other missense variants of uncertain significance showed normal mRNA expression and no abnormalities in protein function. Based on these findings, the frequency of pathogenic TBK1 variants in Korean sALS patients was estimated to be 0.8% (1/129). In conclusion, pathogenic variants in TBK1 are rare but could be responsible for sALS in a small number of Korean patients.
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Affiliation(s)
| | - Ki-Wook Oh
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea; Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Min-Young Noh
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea; Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Minyeop Nahm
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Jinseok Park
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea; Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Su Min Lim
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | | | - Eun-Hae Cho
- Green Cross Genome, Yongin, Republic of Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea; Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea.
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19
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Nahm M, Park S, Lee J, Lee S. MICAL-like Regulates Fasciclin II Membrane Cycling and Synaptic Development. Mol Cells 2016; 39:762-767. [PMID: 27770767 PMCID: PMC5104885 DOI: 10.14348/molcells.2016.0203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 11/27/2022] Open
Abstract
Fasciclin II (FasII), the Drosophila ortholog of neural cell adhesion molecule (NCAM), plays a critical role in synaptic stabilization and plasticity. Although this molecule undergoes constitutive cycling at the synaptic membrane, how its membrane trafficking is regulated to ensure proper synaptic development remains poorly understood. In a genetic screen, we recovered a mutation in Drosophila mical-like that displays an increase in bouton numbers and a decrease in FasII levels at the neuromuscular junction (NMJ). Similar phenotypes were induced by presynaptic, but not postsynaptic, knockdown of mical-like expression. FasII trafficking assays revealed that the recycling of internalized FasII molecules to the cell surface was significantly impaired in mical-like-knockdown cells. Importantly, this defect correlated with an enhancement of endosomal sorting of FasII to the lysosomal degradation pathway. Similarly, synaptic vesicle exocytosis was also impaired in mical-like mutants. Together, our results identify Mical-like as a novel regulator of synaptic growth and FasII endocytic recycling.
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Affiliation(s)
- Minyeop Nahm
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul 08826,
Korea
- School of Dentistry and Dental Research Institute, Seoul National University, Seoul 08826,
Korea
| | - Sunyoung Park
- Interdisciplinary Graduate Program in Brain Science, College of Natural Sciences, Seoul National University, Seoul 08826,
Korea
| | - Jihye Lee
- Department of Oral Pathology and BK21 PLUS Project, School of Dentistry and Institute of Translational Dental Sciences, Pusan National University, Yangsan 50612,
Korea
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul 08826,
Korea
- School of Dentistry and Dental Research Institute, Seoul National University, Seoul 08826,
Korea
- Interdisciplinary Graduate Program in Brain Science, College of Natural Sciences, Seoul National University, Seoul 08826,
Korea
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20
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Lim SM, Choi WJ, Oh KW, Xue Y, Choi JY, Kim SH, Nahm M, Kim YE, Lee J, Noh MY, Lee S, Hwang S, Ki CS, Fu XD, Kim SH. Directly converted patient-specific induced neurons mirror the neuropathology of FUS with disrupted nuclear localization in amyotrophic lateral sclerosis. Mol Neurodegener 2016; 11:8. [PMID: 26795035 PMCID: PMC4722778 DOI: 10.1186/s13024-016-0075-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 01/18/2016] [Indexed: 12/14/2022] Open
Abstract
Background Mutations in the fused in sarcoma (FUS) gene have been linked to amyotrophic lateral sclerosis (ALS). ALS patients with FUS mutations exhibit neuronal cytoplasmic mislocalization of the mutant FUS protein. ALS patients’ fibroblasts or induced pluripotent stem cell (iPSC)-derived neurons have been developed as models for understanding ALS-associated FUS (ALS-FUS) pathology; however, pathological neuronal signatures are not sufficiently present in the fibroblasts of patients, whereas the generation of iPSC-derived neurons from ALS patients requires relatively intricate procedures. Results Here, we report the generation of disease-specific induced neurons (iNeurons) from the fibroblasts of patients who carry three different FUS mutations that were recently identified by direct sequencing and multi-gene panel analysis. The mutations are located at the C-terminal nuclear localization signal (NLS) region of the protein (p.G504Wfs*12, p.R495*, p.Q519E): two de novo mutations in sporadic ALS and one in familial ALS case. Aberrant cytoplasmic mislocalization with nuclear clearance was detected in all patient-derived iNeurons, and oxidative stress further induced the accumulation of cytoplasmic FUS in cytoplasmic granules, thereby recapitulating neuronal pathological features identified in mutant FUS (p.G504Wfs*12)-autopsied ALS patient. Importantly, such FUS pathological hallmarks of the patient with the p.Q519E mutation were only detected in patient-derived iNeurons, which contrasts to predominant FUS (p.Q519E) in the nucleus of both the transfected cells and patient-derived fibroblasts. Conclusions Thus, iNeurons may provide a more reliable model for investigating FUS mutations with disrupted NLS for understanding FUS-associated proteinopathies in ALS. Electronic supplementary material The online version of this article (doi:10.1186/s13024-016-0075-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Su Min Lim
- Department of Translational Medicine, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, 133-792, Republic of Korea. .,Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea.
| | - Won Jun Choi
- Department of Neurology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates.
| | - Ki-Wook Oh
- Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea. .,Department of Neurology, College of Medicine, Hanyang University, Seoul, 133-792, Republic of Korea.
| | - Yuanchao Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Ji Young Choi
- Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea.
| | - Sung Hoon Kim
- Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea.
| | - Minyeop Nahm
- Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea.
| | - Young-Eun Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
| | - Jinhyuk Lee
- Korean Bioinformation Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-806, Republic of Korea. .,Department of Bioinformatics, University of Sciences and Technology, Daejeon, 305-806, Republic of Korea.
| | - Min-Young Noh
- Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea.
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 110-744, Republic of Korea.
| | - Sejin Hwang
- Department of Anatomy and Cell Biology, College of Medicine, Hanyang University, Seoul, 133-792, Republic of Korea.
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
| | - Xiang-Dong Fu
- Department of Cellular Molecular Medicine, University of California, La Jolla, San Diego, CA, 92093, USA.
| | - Seung Hyun Kim
- Department of Translational Medicine, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, 133-792, Republic of Korea. .,Cell Therapy Center, Hanyang University Hospital, Seoul, 133-792, Republic of Korea. .,Department of Neurology, College of Medicine, Hanyang University, Seoul, 133-792, Republic of Korea.
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Lee MJ, Jang S, Nahm M, Yoon JH, Lee S. Tbc1d15-17 regulates synaptic development at the Drosophila neuromuscular junction. Mol Cells 2013; 36:163-8. [PMID: 23812537 PMCID: PMC3887947 DOI: 10.1007/s10059-013-0147-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/23/2013] [Indexed: 11/25/2022] Open
Abstract
Members of the Tre-2/Bub2/Cdc16 (TBC) family of proteins are believed to function as GTPase-activating proteins (GAPs) for Rab GTPases, which play pivotal roles in intracellular membrane trafficking. Although membrane trafficking is fundamental to neuronal morphogenesis and function, the roles of TBC-family Rab GAPs have been poorly characterized in the nervous system. In this paper, we provide genetic evidence that Tbc1d15-17, the Drosophila homolog of mammalian Rab7-GAP TBC1d15, is required for normal presynaptic growth and postsynaptic organization at the neuromuscular junction (NMJ). A loss-of-function mutation in Tbc1d15-17 or its presynaptic knockdown leads to an increase in synaptic bouton number and NMJ length. Tbc1d15-17 mutants are also defective in the distribution of the postsynaptic scaffold Discs-large (Dlg) and in the level of the postsynaptic glutamate subunit GluRIIA. These postsynaptic phenotypes are recapitulated by postsynaptic knockdown of Tbc1d15-17. We also show that presynaptic overexpression of a constitutively active Rab7 mutant in a wild-type background causes a synaptic overgrowth phenotype resembling that of Tbc1d15-17 mutants, while a dominant-negative form of Rab7 has the opposite effect. Together, our findings establish a novel role for Tbc1d15-17 and its potential substrate Rab7 in regulating synaptic development.
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Affiliation(s)
- Min-Jung Lee
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749,
Korea
| | | | - Minyeop Nahm
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749,
Korea
| | | | - Seungbok Lee
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749,
Korea
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Nahm M, Lee MJ, Parkinson W, Lee M, Kim H, Kim YJ, Kim S, Cho YS, Min BM, Bae YC, Broadie K, Lee S. Spartin regulates synaptic growth and neuronal survival by inhibiting BMP-mediated microtubule stabilization. Neuron 2013; 77:680-95. [PMID: 23439121 DOI: 10.1016/j.neuron.2012.12.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2012] [Indexed: 01/06/2023]
Abstract
Troyer syndrome is a hereditary spastic paraplegia caused by human spartin (SPG20) gene mutations. We have generated a Drosophila disease model showing that Spartin functions presynaptically with endocytic adaptor Eps15 to regulate synaptic growth and function. Spartin inhibits bone morphogenetic protein (BMP) signaling by promoting endocytic degradation of BMP receptor wishful thinking (Wit). Drosophila fragile X mental retardation protein (dFMRP) and Futsch/MAP1B are downstream effectors of Spartin and BMP signaling in regulating microtubule stability and synaptic growth. Loss of Spartin or elevation of BMP signaling induces age-dependent progressive defects resembling hereditary spastic paraplegias, including motor dysfunction and brain neurodegeneration. Null spartin phenotypes are prevented by administration of the microtubule-destabilizing drug vinblastine. Together, these results demonstrate that Spartin regulates both synaptic development and neuronal survival by controlling microtubule stability via the BMP-dFMRP-Futsch pathway, suggesting that impaired regulation of microtubule stability is a core pathogenic component in Troyer syndrome.
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Affiliation(s)
- Minyeop Nahm
- Department of Cell and Developmental Biology, Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea
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Dani N, Nahm M, Lee S, Broadie K. A targeted glycan-related gene screen reveals heparan sulfate proteoglycan sulfation regulates WNT and BMP trans-synaptic signaling. PLoS Genet 2012; 8:e1003031. [PMID: 23144627 PMCID: PMC3493450 DOI: 10.1371/journal.pgen.1003031] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 08/26/2012] [Indexed: 12/14/2022] Open
Abstract
A Drosophila transgenic RNAi screen targeting the glycan genome, including all N/O/GAG-glycan biosynthesis/modification enzymes and glycan-binding lectins, was conducted to discover novel glycan functions in synaptogenesis. As proof-of-product, we characterized functionally paired heparan sulfate (HS) 6-O-sulfotransferase (hs6st) and sulfatase (sulf1), which bidirectionally control HS proteoglycan (HSPG) sulfation. RNAi knockdown of hs6st and sulf1 causes opposite effects on functional synapse development, with decreased (hs6st) and increased (sulf1) neurotransmission strength confirmed in null mutants. HSPG co-receptors for WNT and BMP intercellular signaling, Dally-like Protein and Syndecan, are differentially misregulated in the synaptomatrix of these mutants. Consistently, hs6st and sulf1 nulls differentially elevate both WNT (Wingless; Wg) and BMP (Glass Bottom Boat; Gbb) ligand abundance in the synaptomatrix. Anterograde Wg signaling via Wg receptor dFrizzled2 C-terminus nuclear import and retrograde Gbb signaling via synaptic MAD phosphorylation and nuclear import are differentially activated in hs6st and sulf1 mutants. Consequently, transcriptional control of presynaptic glutamate release machinery and postsynaptic glutamate receptors is bidirectionally altered in hs6st and sulf1 mutants, explaining the bidirectional change in synaptic functional strength. Genetic correction of the altered WNT/BMP signaling restores normal synaptic development in both mutant conditions, proving that altered trans-synaptic signaling causes functional differentiation defects.
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Affiliation(s)
- Neil Dani
- Department of Biological Sciences and Department of Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Minyeop Nahm
- Department of Cell and Developmental Biology, Seoul National University, Seoul, Republic of Korea
| | - Seungbok Lee
- Department of Cell and Developmental Biology, Seoul National University, Seoul, Republic of Korea
| | - Kendal Broadie
- Department of Biological Sciences and Department of Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee, United States of America
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24
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Lee S, Kim S, Nahm M, Kim E, Kim TI, Yoon JH, Lee S. The phosphoinositide phosphatase Sac1 is required for midline axon guidance. Mol Cells 2011; 32:477-82. [PMID: 22042447 PMCID: PMC3887689 DOI: 10.1007/s10059-011-0168-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 08/29/2011] [Indexed: 12/23/2022] Open
Abstract
Sac1 phosphoinositide (PI) phosphatases are important regulators of PtdIns(4)P turnover at the ER, Golgi, and plasma membrane (PM) and are involved in diverse cellular processes including cytoskeletal organization and vesicular trafficking. Here, we present evidence that Sac1 regulates axon guidance in the embryonic CNS of Drosophila. Sac1 is expressed on three longitudinal axon tracts that are defined by the cell adhesion molecule Fasciclin II (Fas II). Mutations in the sac1 gene cause ectopic midline crossing of Fas II-positive axon tracts. This phenotype is rescued by neuronal expression of wild-type Sac1 but not by a catalytically-inactive mutant. Finally, sac1 displays dosage-sensitive genetic interactions with mutations in the genes that encode the midline repellent Slit and its axonal receptor Robo. Taken together, our results suggest that Sac1-mediated regulation of PIs is critical for Slit/Robo-dependent axon repulsion at the CNS midline.
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Affiliation(s)
- Seongsoo Lee
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Korea
- These authors contributed equally to this work
| | - Sungdae Kim
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul 151-742, Korea
- These authors contributed equally to this work
| | - Minyeop Nahm
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Korea
| | - Euijae Kim
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Korea
| | - Tai-Il Kim
- Department of Periodontology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Korea
| | - Jin Ho Yoon
- Basic Science Research Institute, School of Biological Science and Chemistry, Sungshin Women’s University, Seoul 142-732, Korea
| | - Seungbok Lee
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Korea
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul 151-742, Korea
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Abstract
Rho small GTPases control multiple aspects of neuronal morphogenesis by regulating the assembly and organization of the actin cytoskeleton. Although they are negatively regulated by GTPase activating proteins (GAPs), the roles of RhoGAPs in the nervous system have not been fully investigated. Here we describe a characterization of Drosophila RhoGAP68F that is mainly expressed in the embryonic central nervous system. RNA in situ hybridization analysis showed that expression of RhoGAP68F is highly restricted to the embryonic brain and ventral nerve cord. Database search revealed that RhoGAP68F contains an N-terminal Sec14 domain and a C-terminal RhoGAP domain. Rho-GTP pull-down assay demonstrated that the RhoGAP domain of RhoGAP68F inactivates RhoA but not Rac1 or Cdc42 in HEK293 cells. In addition, expression of RhoGAP68F in NIH3T3 cells suppressed LPA-induced stress fiber formation, which is mediated by RhoA. Finally, neuronal overexpression of RhoGAP68F causes synaptic overgrowth at the larval neuromuscular junction (NMJ). Taken together, these results suggest that RhoGAP68F may play a role in synaptic growth regulation by inactivating RhoA.
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Affiliation(s)
- Minyeop Nahm
- Department of Cell and Developmental Biology, Dental Research Institute, Seoul National University, Seoul 110-749, Korea
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26
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Nahm M, Long AA, Paik SK, Kim S, Bae YC, Broadie K, Lee S. The Cdc42-selective GAP rich regulates postsynaptic development and retrograde BMP transsynaptic signaling. ACTA ACUST UNITED AC 2010; 191:661-75. [PMID: 21041451 PMCID: PMC3003324 DOI: 10.1083/jcb.201007086] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inhibition of Cdc42 by dRich induces postsynaptic release of the BMP ligand Glass bottom boat. Retrograde bone morphogenetic protein signaling mediated by the Glass bottom boat (Gbb) ligand modulates structural and functional synaptogenesis at the Drosophila melanogaster neuromuscular junction. However, the molecular mechanisms regulating postsynaptic Gbb release are poorly understood. In this study, we show that Drosophila Rich (dRich), a conserved Cdc42-selective guanosine triphosphatase–activating protein (GAP), inhibits the Cdc42–Wsp pathway to stimulate postsynaptic Gbb release. Loss of dRich causes synaptic undergrowth and strongly impairs neurotransmitter release. These presynaptic defects are rescued by targeted postsynaptic expression of wild-type dRich but not a GAP-deficient mutant. dRich inhibits the postsynaptic localization of the Cdc42 effector Wsp (Drosophila orthologue of mammalian Wiskott-Aldrich syndrome protein, WASp), and manifestation of synaptogenesis defects in drich mutants requires Wsp signaling. In addition, dRich regulates postsynaptic organization independently of Cdc42. Importantly, dRich increases Gbb release and elevates presynaptic phosphorylated Mad levels. We propose that dRich coordinates the Gbb-dependent modulation of synaptic growth and function with postsynaptic development.
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Affiliation(s)
- Minyeop Nahm
- Interdisplinary Program in Brain Science, Seoul National University, Seoul, Republic of Korea
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27
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28
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Lee S, Nahm M, Lee M, Kwon M, Kim E, Zadeh AD, Cao H, Kim HJ, Lee ZH, Oh SB, Yim J, Kolodziej PA, Lee S. The F-actin-microtubule crosslinker Shot is a platform for Krasavietz-mediated translational regulation of midline axon repulsion. Development 2007; 134:1767-77. [PMID: 17409115 DOI: 10.1242/dev.02842] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Axon extension and guidance require a coordinated assembly of F-actin and microtubules as well as regulated translation. The molecular basis of how the translation of mRNAs encoding guidance proteins could be closely tied to the pace of cytoskeletal assembly is poorly understood. Previous studies have shown that the F-actin-microtubule crosslinker Short stop (Shot) is required for motor and sensory axon extension in the Drosophila embryo. Here, we provide biochemical and genetic evidence that Shot functions with a novel translation inhibitor, Krasavietz (Kra, Exba), to steer longitudinally directed CNS axons away from the midline. Kra binds directly to the C-terminus of Shot, and this interaction is required for the activity of Shot to support midline axon repulsion. shot and kra mutations lead to weak robo-like phenotypes, and synergistically affect midline avoidance of CNS axons. We also show that shot and kra dominantly enhance the frequency of midline crossovers in embryos heterozygous for slit or robo, and that in kra mutant embryos, some Robo-positive axons ectopically cross the midline that normally expresses the repellent Slit. Finally, we demonstrate that Kra also interacts with the translation initiation factor eIF2beta and inhibits translation in vitro. Together, these data suggest that Kra-mediated translational regulation plays important roles in midline axon repulsion and that Shot functions as a direct physical link between translational regulation and cytoskeleton reorganization.
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Affiliation(s)
- Seongsoo Lee
- Department of Cell and Developmental Biology, School of Dentistry, Seoul National University, Seoul, Republic of Korea
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29
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Nahm M, Lee M, Baek SH, Yoon JH, Kim HH, Lee ZH, Lee S. Drosophila RhoGEF4 encodes a novel RhoA-specific guanine exchange factor that is highly expressed in the embryonic central nervous system. Gene 2006; 384:139-44. [PMID: 17011730 DOI: 10.1016/j.gene.2006.07.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2006] [Revised: 07/17/2006] [Accepted: 07/21/2006] [Indexed: 11/28/2022]
Abstract
Rho family small GTPases act as molecular switches that regulate neuronal morphogenesis, including axon growth and guidance, dendritic spine formation, and synapse formation. These proteins are positively regulated by guanine nucleotide exchange factors (GEFs) of the Dbl family. This study describes the identification and characterization of Drosophila RhoGEF4 (DRhoGEF4), a novel Dbl family protein that is specifically expressed in the central nervous system during Drosophila embryogenesis. The predicted amino acid sequence of DRhoGEF4 contains a Dbl homology (DH) domain and an adjacent C-terminal pleckstrin homology (PH) domain, which are most closely related to those of mammalian frabins. In this study, the DH-PH motif is shown to enhance the dissociation of GDP from either RhoA or Rac1 but not from Cdc42 in vitro. In addition, p21-binding domain pull-down assays demonstrate that DRhoGEF4 activates RhoA, but neither Rac1 nor Cdc42 in HEK293 cells. Finally, overexpression of DRhoGEF4 is able to induce assembly of stress fibers in cultured NIH3T3 cells. Taken together, these findings suggest that DRhoGEF4 may participate in cytoskeleton-related cellular events by specifically activating RhoA in neuronal morphogenesis.
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Affiliation(s)
- Minyeop Nahm
- Interdisciplinary Program in Brain Science, School of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
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30
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Nahm M, Radoglou K, Halyvopoulos G, Gessler A, Rennenberg H, Fotelli MN. Physiological performance of beech (Fagus sylvatica L.) at its southeastern distribution limit in Europe: seasonal changes in nitrogen, carbon and water balance. Plant Biol (Stuttg) 2006; 8:52-63. [PMID: 16435269 DOI: 10.1055/s-2005-872988] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
To assess the physiological performance of drought-sensitive European beech ( Fagus sylvatica L.) under the dry Mediterranean climate prevailing at its southeastern distribution limit in Europe, we analyzed seasonal changes in carbon, nitrogen and water balance of naturally grown adult trees. We determined the foliar C and N contents, delta13C and delta18O signatures, total soluble non-protein nitrogen compounds (TSNN) in xylem, leaves, and phloem, as well as leaf water potential and photosynthetic quantum yield in northern Greece during 2003. Tissue sampling was performed in May, July, and September, while field measurements were conducted regularly. Climatic conditions for the 2003 growing season fall within the typical range of the studied area. The N- and C-related parameters displayed distinct seasonal courses. TSNN was highest in May in all tissues, and asparagine (Asn) was then the most abundant compound. Thereafter, TSNN decreased significantly in all tissues and both its concentration and composition remained constant in July and September. In both months, glutamate (Glu) prevailed in leaves, gamma-aminobutyric acid (GABA) in phloem exudates from twigs and trunks, and arginine (Arg) in the xylem sap, where loading with amino acids was rather low during that period, amounting to only 0.8 micromol N ml-1 in September. Highest total foliar N and C contents were detected in May, and the elevated abundance of nutrients as well as an increased foliar delta13C signature at the beginning of the growing season is attributed to remobilization processes. The signatures of delta18O, quantum yield and leaf water potentials varied only slightly throughout the growing season. Although summer precipitation at the study site was considerably lower compared to what is usual for typical central European beech forests, no intensive drought responses of the physiological apparatus were detected in the studied beech trees. This suggests efficient internal regulation mechanisms, constantly ensuring a favourable physiological status under the relatively dry Mediterranean climate.
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Affiliation(s)
- M Nahm
- Tree Physiology, Institute of Forest Botany and Tree Physiology, Albert Ludwig University of Freiburg, Georges Köhler Allee, Geb. 053/054, 79110 Freiburg i. Br., Germany
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31
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Gessler A, Keitel C, Nahm M, Rennenberg H. Water shortage affects the water and nitrogen balance in Central European beech forests. Plant Biol (Stuttg) 2004; 6:289-298. [PMID: 15143437 DOI: 10.1055/s-2004-820878] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Whilst forest policy promotes cultivation and regeneration of beech dominated forest ecosystems, beech itself is a highly drought sensitive tree species likely to suffer from the climatic conditions prognosticated for the current century. Taking advantage of model ecosystems with cool-moist and warm-dry local climate, the latter assumed to be representative for future climatic conditions, the effects of climate and silvicultural treatment (different thinning regimes) on water status, nitrogen balance and growth parameters of adult beech trees and beech regeneration in the understorey were assessed. In addition, validation experiments with beech seedlings were carried out under controlled conditions, mainly in order to assess the effect of drought on the competitive abilities of beech. As measures of water availability xylem flow, shoot water potential, stomatal conductance as well as delta (13)C and delta (18)O in different tissues (leaves, phloem, wood) were analysed. For the assessment of nitrogen balance we determined the uptake of inorganic nitrogen by the roots as well as total N content and soluble N compounds in different tissues of adult and young trees. Retrospective and current analysis of delta (13)C, growth and meteorological parameters revealed that beech growing under warm-dry climatic conditions were impaired in growth and water balance during periods with low rain-fall. Thinning affected water, N balance and growth mostly of young beech, but in a different way under different local climatic conditions. Under cool, moist conditions, representative for the current climatic and edaphic conditions in beech forests of Central Europe, thinning improves nutrient and water status consistent to published literature and long-term experience of forest practitioners. However, beech regeneration was impaired as a result of thinning at higher temperatures and under reduced water availability, as expected in future climate.
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Affiliation(s)
- A Gessler
- Institute of Forest Botany and Tree Physiology, Albert Ludwigs University of Freiburg, Freiburg, Germany.
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32
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Kim H, Nahm M, Lim C, Yun D, Cho M, Bahk J. A rac-like small G-protein from Brassica campestris activates a PKC-dependent phospholipase D. Phytochemistry 2004; 65:71-80. [PMID: 14697272 DOI: 10.1016/j.phytochem.2003.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A cDNA clone encoding a rac-like small GTP binding protein was isolated from a cDNA library of Chinese cabbage (Brassica campestris L. ssp. pekinensis) flower buds and named Brac1. The Brac1 cDNA contains an open reading frame encoding 198 amino acid residues with an estimated molecular mass of 21,690 Da and this coding region has conserved residues and motifs unique to the Rho subfamily of proteins. The deduced amino acid sequence of the Brac1 protein is closely related to that of Arabidopsis thaliana Arac3 (91%), but it shares relatively little homology with other members of the Ras superfamily (about 30% identity). To further characterize Brac1, a pGBrac1 expression vector consisting of PCR-amplified Brac1 cDNA plus glutathione S-transferase (GST) and pBKS(+)II was used to purify the protein. Using a PEI-cellulose/TLC plate, GTPase activity of this protein was confirmed and competition binding studies, using the guanine nucleotides, ATP, UTP and CTP, revealed that the di- and triphosphate forms of guanine nucleotides strongly bind Brac1. Membrane-bound PLD activity was synergistically enhanced by Brac1 in the presence of protein kinase C, but not in the presence of ARF (ADP-ribosylation factor). Genomic analysis indicated that Brac1 belongs to a multigene family. Brac1 transcripts were expressed in all the organs of Brassica, but were especially prevalent in flower buds.
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Affiliation(s)
- Hoyeon Kim
- Division of Applied Life Sciences, Graduate School of Gyeongsang National University, 660-701, Jinju, South Korea
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33
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Rapoport AP, Simons-Evelyn M, Chen T, Sidell R, Luhowskyj S, Rosell K, Obrig T, Hicks D, Hinkle PM, Nahm M, Insel RA, Abboud CN. Flavopiridol induces apoptosis and caspase-3 activation of a newly characterized Burkitt's lymphoma cell line containing mutant p53 genes. Blood Cells Mol Dis 2001; 27:610-24. [PMID: 11482875 DOI: 10.1006/bcmd.2001.0428] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Burkitt's lymphoma cell lines have been important in vitro models for studying the pathogenesis of Burkitt's lymphoma (BL) and for exploring new treatment strategies. A new EBV(-) Burkitt's lymphoma cell line (GA-10) was established from a patient with a clinically aggressive, chemorefractory BL and characterized. Although functional p-glycoprotein could not be demonstrated by dye-efflux assays, both p53 genes were mutated in the GA-10 cells, perhaps contributing to the resistant phenotype of the original neoplasm. Two properties of BL cells which may be useful targets for novel cytotoxic therapeutics are their surface expression of CD77, the receptor for Shiga toxin (Stx), and their high rate of proliferation. Expression of CD77 on the GA-10 cells was heterogeneous in that certain subclones expressed high levels of CD77 and correspondingly exhibited strong growth inhibition by Stx while others showed low levels of CD77 expression and weak Stx-induced growth inhibition. Flavopiridol, a potent inhibitor of cell cycle progression through G1 and G2, induced cytotoxicity of the GA-10 cells with an LC(50) of approximately 40 nM vs 70 nM for HL-60 cells (P < 0.05). The concentrations of flavopiridol at which only 10% of the cells were viable (LC(10)) were approximately 280 nM for the GA-10 cells and 520 nM for the HL-60 cells (P < 0.05). Dose-related induction of apoptosis in response to flavopiridol was demonstrated in the GA-10 cells by morphology, TUNEL assay, and activation of caspase-3. Flavopiridol was also cytotoxic to seven other BL cell lines tested. These data suggest that flavopiridol may have therapeutic value in the treatment of Burkitt's lymphoma.
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Affiliation(s)
- A P Rapoport
- University of Maryland Greenebaum Cancer Center, 22 South Greene Street, Baltimore, MD 21201, USA.
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34
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Jansen WT, Väkeväinen-Anttila M, Käyhty H, Nahm M, Bakker N, Verhoef J, Snippe H, Verheul AF. Comparison of a classical phagocytosis assay and a flow cytometry assay for assessment of the phagocytic capacity of sera from adults vaccinated with a pneumococcal conjugate vaccine. Clin Diagn Lab Immunol 2001; 8:245-50. [PMID: 11238203 PMCID: PMC96044 DOI: 10.1128/cdli.8.2.245-250.2001] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Antibody- and complement-mediated phagocytosis is the main defense mechanism against Streptococcus pneumoniae. A standardized, easy to perform phagocytosis assay for pneumococci would be a great asset for the evaluation of the potential efficacy of (experimental) pneumococcal vaccines. Such an assay could replace the laborious phagocytosis assay of viable pneumococci (classical killing assay). Therefore, a newly developed phagocytosis assay based on flow cytometry (flow assay) was compared with the conventional killing assay and enzyme-linked immunosorbent assay (ELISA), using sera obtained from adults pre- and postvaccination with either a bivalent conjugate, a tetravalent conjugate, or the 23-valent polysaccharide vaccine. Highly significant correlations were observed between flow assay phagocytosis titers, killing assay phagocytosis titers, and ELISA antibody titers for serotype 6B and 23F as well. For serotype 19F, strong correlations were only observed between killing assay and ELISA titers. A potential drawback of the flow assay might be the low sensitivity compared with that of the killing assay. The choice of what assay to use, however, will depend on the objectives of the assay. When speed, easy performance, sample throughput, improved worker safety, absence of influence of antibiotics, and absence of false positives are the major criteria, the flow assay is the method of choice. When higher sensitivity is the major requirement, the classical killing assay should be used.
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Affiliation(s)
- W T Jansen
- Eijkman-Winkler Institute for Microbiology, Infectious Diseases, and Inflammation, Vaccines Section, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
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Hockenbery DM, Zutter M, Hickey W, Nahm M, Korsmeyer SJ. BCL2 protein is topographically restricted in tissues characterized by apoptotic cell death. Proc Natl Acad Sci U S A 1991; 88:6961-5. [PMID: 1871110 PMCID: PMC52213 DOI: 10.1073/pnas.88.16.6961] [Citation(s) in RCA: 853] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The BCL2 protooncogene encodes an inner mitochondrial membrane protein that blocks programmed cell death. BCL2 was isolated from the chromosomal breakpoint of follicular B-cell lymphoma. Transgenic mice that overexpress BCL2 display extended survival of resting B cells. In this study we use a monospecific anti-human BCL2 antibody to define the distribution of BCL2 protein within organized tissues. BCL2 is restricted within germinal centers to the follicular mantle and to portions of the light zone implicated in the selection and maintenance of plasma cells and memory B cells. BCL2 is present in the surviving T cells in the thymic medulla. All hematopoietic lineages that derive from a renewing stem cell also display BCL2. A limited number of nonlymphoid tissues demonstrate BCL2 and can be grouped as (i) glandular epithelium in which hormones or growth factors regulate hyperplasia and involution, (ii) complex differentiating epithelium such as skin and intestine characterized by long-lived stem cells, and (iii) long-lived postmitotic cells such as neurons. Within these tissues that demonstrate apoptotic cell turnover, BCL2 is often topographically restricted to long-lived or proliferating cell zones. BCL2's function as an antidote to apoptosis may confer longevity to progenitor and effector cells in these tissues.
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Affiliation(s)
- D M Hockenbery
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
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MacDermott RP, Jendrisak GA, Nash GS, Schreiber S, Bertovich MJ, Nahm M, Nonaka M, Fitzgerald P, Katz DH, Marcelletti JF. Human rib bone marrow mononuclear cells spontaneously synthesize and secrete IgE in vitro. Clin Exp Immunol 1991; 83:163-8. [PMID: 1988224 PMCID: PMC1535479 DOI: 10.1111/j.1365-2249.1991.tb05608.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have examined spontaneous secretion of IgE by human rib bone marrow mononuclear cells (MNC). Bone marrow MNC from nine out of 12 rib specimens synthesized and secreted substantial amounts of IgE during 14 days of in vitro culture. The 14-day supernatants from these bone marrow MNC contained a mean of 2589 pg/ml of IgE (n = 12) with a maximum production of 15,408 pg/ml of IgE compared with small amounts of IgE (80-200 pg/ml) produced by similarly cultured normal and inflammatory bowel disease intestinal lamina propria MNC. Using two rib specimens, time-course studies revealed spontaneous secretion of IgE to be minimal during the first 2 days of culture (152 pg/ml), followed by a steady increase between days 4 (517 pg/ml) and 14 (3588 pg/ml). The addition of pokeweed mitogen resulted in 72% suppression of spontaneous IgE production by bone marrow MNC. The bone marrow MNC isolated from the ribs consisted of 22% Leu12+ (B) cells of which 3.2% were surface IgE positive. Staining for cytoplasmic immunoglobulin revealed 1% of the bone marrow MNC to be cytoplasmic IgE+. The presence of IgE-bearing and IgE-secreting MNC in human bone marrow is consistent with the observation that allergen-specific IgE-mediated hypersensitivity is adoptively transferred by human bone marrow transplantation and demonstrates the usefulness of human bone marrow MNC for examination of IgE secretory and regulatory events.
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Affiliation(s)
- R P MacDermott
- Gastroenterology Section, University of Pennsylvania School of Medicine, Philadelphia 19104-6144
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Briles DE, Scott G, Gray B, Crain MJ, Blaese M, Nahm M, Scott V, Haber P. Naturally occurring antibodies to phosphocholine as a potential index of antibody responsiveness to polysaccharides. J Infect Dis 1987; 155:1307-14. [PMID: 3572041 DOI: 10.1093/infdis/155.6.1307] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Naturally occurring antibodies reactive with the phosphocholine (PC) determinant of pneumococcal teichoic acids may be useful for evaluating the potential of patients to make antibodies to polysaccharides. Antibodies to PC are present in most adults under the age of 60 years, are absent in very young children, and are present at low levels in Wiscott-Aldrich patients and in IgG2-deficient adults. These last three groups respond very poorly to polysaccharide antigens. Antibodies to PC are also found at low levels in the elderly, a group that has previously been shown to have low levels of antibody to blood groups A and B carbohydrates. The levels of antibody to PC over time were constant in most individuals and, in adults, seemed to show slightly less variation than did titers of antibody to blood group B. Our findings suggest that titers of antibody to PC may be superior to titers of antibody to blood group A or B for monitoring responsiveness to carbohydrate antigens.
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Abstract
To facilitate assays for human IgG subclasses, we have adapted a novel assay method (particle concentration fluorescence immunoassay) (Jolley et al., 1984; MacCrindle et al., 1985) using one polyclonal and several monoclonal antibodies for human IgG subclasses. The advantages of this new assay over previously described methods are sensitivity (0.3-3 micrograms/ml), and automated measurement of multiple samples in a short time (2 h). We found that a monkey antibody for IgG2 and monoclonal antibodies for IgG1, IgG4b epitope, and IgG3 can be adapted to this method. We evaluated 7 different antibodies to IgG4 without finding a suitable monoclonal antibody for this assay method. Several of these IgG4 hybridoma antibodies, however, could be used in a competitive radioimmunoassay using polyvinyl microtiter plates. The usefulness of a monoclonal antibody to the IgG4b epitope was evaluated because no suitable monoclonal antibodies for IgG2 are available. Because IgG4 levels are usually much smaller than IgG2 levels, and the IgG4b epitope is expressed on all IgG2 alleles and only some IgG4 alleles (Kunkel et al., 1970), the antibody for IgG4b is potentially useful to screen a large number of samples for IgG2 deficiency. However, when the monoclonal antibody for IgG4b was compared with an IgG2 specific antibody produced in a monkey, the IgG4b antibody could identify only about half of the patients with known IgG2 deficiency.
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Hauptfeld V, Nahm M, Hauptfeld M, Shreffler DC. Monoclonal antibodies to mouse MHC antigens. I. Serologic characterization of ten anti-H-2 and anti-Ia reagents. Immunogenetics 1984; 19:169-73. [PMID: 6583159 DOI: 10.1007/bf00387861] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Abstract
Most mouse strains are able to mount a diverse antibody response against group A streptococcal carbohydrate (GAC). We have previously reported that murine anti-GAC antibodies are for the most part restricted to IgM and IgG3 subclasses. In addition, despite extensive heterogeneity in their isoelectric focusing patterns, greater than 50% of A/J anti-GAC antibodies share a common light chain defined by spectrotypic and idiotypic (VK1GAC) criteria. We have used protein and DNA sequencing strategies to examine the genetic basis of diversity in murine anti-GAC antibodies. In particular, we report that, (a) multiple, closely homologous VH gene segments contribute to the generation of anti-GAC antibodies, (b) a common framework sequence, related to the VK27 subgroup, probably defines VK1GAC, and (c) the A/J anti-GAC VH regions and BALB/c anti-inulin VH sequences are 95% homologous at the protein level and are likely encoded by overlapping VH gene families. Lastly, we discuss the genetic mechanisms that might permit the evolution of multiple, closely homologous germline VH gene segments in the context of highly divergent flanking region sequences.
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Briles DE, Nahm M, Marion TN, Perlmutter RM, Davie JM. Streptococcal group A carbohydrate has properties of both a thymus-independent (TI-2) and a thymus-dependent antigen. J Immunol 1982; 128:2032-5. [PMID: 7037958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Streptococcal group A carbohydrate, which elicits mouse antibody of primarily the IgM and IgG3 isotypes, is relatively nonimmunogenic in nu/nu or xid mice, and thus appears to be a type of TD-2 antigen. The TD-2 antigens described previously have been proteins that elicit IgG antibody primarily of the IgG1 and IgG2 isotypes. Our findings indicate that TD-2 properties may also be a characteristic of at least some carbohydrate antigens that can elicit IgG antibody predominantly of the IgG3 class.
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Briles DE, Nahm M, Marion TN, Perlmutter RM, Davie JM. Streptococcal group A carbohydrate has properties of both a thymus-independent (TI-2) and a thymus-dependent antigen. The Journal of Immunology 1982. [DOI: 10.4049/jimmunol.128.5.2032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Streptococcal group A carbohydrate, which elicits mouse antibody of primarily the IgM and IgG3 isotypes, is relatively nonimmunogenic in nu/nu or xid mice, and thus appears to be a type of TD-2 antigen. The TD-2 antigens described previously have been proteins that elicit IgG antibody primarily of the IgG1 and IgG2 isotypes. Our findings indicate that TD-2 properties may also be a characteristic of at least some carbohydrate antigens that can elicit IgG antibody predominantly of the IgG3 class.
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Briles DE, Nahm M, Schroer K, Davie J, Baker P, Kearney J, Barletta R. Antiphosphocholine antibodies found in normal mouse serum are protective against intravenous infection with type 3 streptococcus pneumoniae. J Exp Med 1981; 153:694-705. [PMID: 7252411 PMCID: PMC2186108 DOI: 10.1084/jem.153.3.694] [Citation(s) in RCA: 392] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The antiphosphocholine (PC) antibody in normal mouse sera (NMS) provides protection against intravenous infection with encapsulated strain WU2 of type 3 Streptococcus pneumoniae. Mice unable to make anti-PC antibody, as a result of suppression with anti-T-15 idiotype or inheritance of the xid gene of CAB/N mice, are highly susceptible to infection with strain WU2. Mice inheriting the xid gene can be protected with NMS from immunologically normal mice or with IgM hybridoma anti-PC antibody. The protective effect of NMS can be removed with PC-containing immunoabsorbents.
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Nahm M, Der-Balian GP, Venturini D, Bazin H, Davie JM. Antigenic similarities of rat and mouse IgG subclasses associated with anti-carbohydrate specificities. Immunogenetics 1980; 11:199-203. [PMID: 6157646 DOI: 10.1007/bf01567785] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Slack J, Der-Balian GP, Nahm M, Davie JM. Subclass restriction of murine antibodies. II. The IgG plaque-forming cell response to thymus-independent type 1 and type 2 antigens in normal mice and mice expressing an X-linked immunodeficiency. J Exp Med 1980; 151:853-62. [PMID: 6966310 PMCID: PMC2185832 DOI: 10.1084/jem.151.4.853] [Citation(s) in RCA: 215] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Antigens have been classified previously into three categories, thymus-dependent (TD), thymus-independent type (TI) 1, and TI-2, based upon thymic dependence and ability to stimulate an immunodeficient strain of mouse, CBA/N. Here we demonstrate that the different antigen classes elicit IgG antibodies of different subclasses. TD antigens stimulate predominantly IgG1 antibodies, with smaller amounts of IgG2 and IgG3 being expressed. TI-1 antigens stimulate almost no IgG1 antibodies and equal amounts of IgG2 and IgG3. TI-2 antigens elicit predominantly IgG3 antibodies. Mice expressing the CBA/N phenotype are known to be nonresponsive to TI-2 antigens. This was confirmed in this study. In addition, we demonstrate that the IgG3 component of the response to TI-1 antigens is virtually absent in mice expressing the CBA/N phenotype, which supports our previous finding that the CBA/N defect may be restricted to a B-lymphocyte subpopulation containing most of the precursors of IgG3-secreting cells.
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Perlmutter RM, Nahm M, Stein KE, Slack J, Zitron I, Paul WE, Davie JM. Immunoglobulin subclass-specific immunodeficiency in mice with an X-linked B-lymphocyte defect. J Exp Med 1979; 149:993-8. [PMID: 311819 PMCID: PMC2184855 DOI: 10.1084/jem.149.4.993] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
CBA/N mice express an X-linked deficiency in their antibody response to many bacterial carbohydrates; we have shown recently that these antigens normally elicit antibody responses predominantly of the IgM and IgG3 isotypes. Here we demonstrate that mice, with the CBA/N phenotype have perferential deficiencies of IgM and IgG3 immunoglobulin expression, both when measured in serum and in cells secreting these isotypes, and that this deficiency is only partially corrected by polyclonal activation of B cells. This suggests that CBA/N mice may lack a subpopulation of B cells that contain most of the IgG3 precursors.
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