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Moors TE, Morella ML, Bertran-Cobo C, Geut H, Udayar V, Timmermans-Huisman E, Ingrassia AMT, Brevé JJP, Bol JGJM, Bonifati V, Jagasia R, van de Berg WDJ. Altered TFEB subcellular localization in nigral neurons of subjects with incidental, sporadic and GBA-related Lewy body diseases. Acta Neuropathol 2024; 147:67. [PMID: 38581586 PMCID: PMC10998821 DOI: 10.1007/s00401-024-02707-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 02/14/2024] [Accepted: 02/14/2024] [Indexed: 04/08/2024]
Abstract
Transcription factor EB (TFEB) is a master regulator of genes involved in the maintenance of autophagic and lysosomal homeostasis, processes which have been implicated in the pathogenesis of GBA-related and sporadic Parkinson's disease (PD), and dementia with Lewy bodies (DLB). TFEB activation results in its translocation from the cytosol to the nucleus. Here, we investigated TFEB subcellular localization and its relation to intracellular alpha-synuclein (aSyn) accumulation in post-mortem human brain of individuals with either incidental Lewy body disease (iLBD), GBA-related PD/DLB (GBA-PD/DLB) or sporadic PD/DLB (sPD/DLB), compared to control subjects. We analyzed nigral dopaminergic neurons using high-resolution confocal and stimulated emission depletion (STED) microscopy and semi-quantitatively scored the TFEB subcellular localization patterns. We observed reduced nuclear TFEB immunoreactivity in PD/DLB patients compared to controls, both in sporadic and GBA-related cases, as well as in iLBD cases. Nuclear depletion of TFEB was more pronounced in neurons with Ser129-phosphorylated (pSer129) aSyn accumulation in all groups. Importantly, we observed previously-unidentified TFEB-immunopositive perinuclear clusters in human dopaminergic neurons, which localized at the Golgi apparatus. These TFEB clusters were more frequently observed and more severe in iLBD, sPD/DLB and GBA-PD/DLB compared to controls, particularly in pSer129 aSyn-positive neurons, but also in neurons lacking detectable aSyn accumulation. In aSyn-negative cells, cytoplasmic TFEB clusters were more frequently observed in GBA-PD/DLB and iLBD patients, and correlated with reduced GBA enzymatic activity as well as increased Braak LB stage. Altered TFEB distribution was accompanied by a reduction in overall mRNA expression levels of selected TFEB-regulated genes, indicating a possible early dysfunction of lysosomal regulation. Overall, we observed cytoplasmic TFEB retention and accumulation at the Golgi in cells without apparent pSer129 aSyn accumulation in iLBD and PD/DLB patients. This suggests potential TFEB impairment at the early stages of cellular disease and underscores TFEB as a promising therapeutic target for synucleinopathies.
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Affiliation(s)
- Tim E Moors
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Martino L Morella
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Cesc Bertran-Cobo
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Hanneke Geut
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Vinod Udayar
- Roche Pharma Research and Early Development; Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center, Basel, Switzerland
| | - Evelien Timmermans-Huisman
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Angela M T Ingrassia
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - John J P Brevé
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - John G J M Bol
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Vincenzo Bonifati
- Erasmus MC, Department of Clinical Genetics, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ravi Jagasia
- Roche Pharma Research and Early Development; Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center, Basel, Switzerland
| | - Wilma D J van de Berg
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands.
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands.
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2
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Erol ÖD, Şenocak Ş, Aerts-Kaya F. The Role of Rab GTPases in the development of genetic and malignant diseases. Mol Cell Biochem 2024; 479:255-281. [PMID: 37060515 DOI: 10.1007/s11010-023-04727-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 04/01/2023] [Indexed: 04/16/2023]
Abstract
Small GTPases have been shown to play an important role in several cellular functions, including cytoskeletal remodeling, cell polarity, intracellular trafficking, cell-cycle, progression and lipid transformation. The Ras-associated binding (Rab) family of GTPases constitutes the largest family of GTPases and consists of almost 70 known members of small GTPases in humans, which are known to play an important role in the regulation of intracellular membrane trafficking, membrane identity, vesicle budding, uncoating, motility and fusion of membranes. Mutations in Rab genes can cause a wide range of inherited genetic diseases, ranging from neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease (AD) to immune dysregulation/deficiency syndromes, like Griscelli Syndrome Type II (GS-II) and hemophagocytic lymphohistiocytosis (HLH), as well as a variety of cancers. Here, we provide an extended overview of human Rabs, discussing their function and diseases related to Rabs and Rab effectors, as well as focusing on effects of (aberrant) Rab expression. We aim to underline their importance in health and the development of genetic and malignant diseases by assessing their role in cellular structure, regulation, function and biology and discuss the possible use of stem cell gene therapy, as well as targeting of Rabs in order to treat malignancies, but also to monitor recurrence of cancer and metastasis through the use of Rabs as biomarkers. Future research should shed further light on the roles of Rabs in the development of multifactorial diseases, such as diabetes and assess Rabs as a possible treatment target.
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Affiliation(s)
- Özgür Doğuş Erol
- Department of Stem Cell Sciences, Hacettepe University Graduate School of Health Sciences, 06100, Ankara, Turkey
- Hacettepe University Center for Stem Cell Research and Development, 06100, Ankara, Turkey
| | - Şimal Şenocak
- Department of Stem Cell Sciences, Hacettepe University Graduate School of Health Sciences, 06100, Ankara, Turkey
- Hacettepe University Center for Stem Cell Research and Development, 06100, Ankara, Turkey
| | - Fatima Aerts-Kaya
- Department of Stem Cell Sciences, Hacettepe University Graduate School of Health Sciences, 06100, Ankara, Turkey.
- Hacettepe University Center for Stem Cell Research and Development, 06100, Ankara, Turkey.
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3
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Kumar R, Khan M, Francis V, Aguila A, Kulasekaran G, Banks E, McPherson PS. DENND6A links Arl8b to a Rab34/RILP/dynein complex, regulating lysosomal positioning and autophagy. Nat Commun 2024; 15:919. [PMID: 38296963 PMCID: PMC10830484 DOI: 10.1038/s41467-024-44957-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 01/08/2024] [Indexed: 02/02/2024] Open
Abstract
Lysosomes help maintain cellular proteostasis, and defects in lysosomal positioning and function can cause disease, including neurodegenerative disorders. The spatiotemporal distribution of lysosomes is regulated by small GTPases including Rabs, which are activated by guanine nucleotide exchange factors (GEFs). DENN domain proteins are the largest family of Rab GEFs. Using a cell-based assay, we screened DENND6A, a member of the DENN domain protein family against all known Rabs and identified it as a potential GEF for 20 Rabs, including Rab34. Here, we demonstrate that DENND6A activates Rab34, which recruits a RILP/dynein complex to lysosomes, promoting lysosome retrograde transport. Further, we identify DENND6A as an effector of Arl8b, a major regulatory GTPase on lysosomes. We demonstrate that Arl8b recruits DENND6A to peripheral lysosomes to activate Rab34 and initiate retrograde transport, regulating nutrient-dependent lysosomal juxtanuclear repositioning. Loss of DENND6A impairs autophagic flux. Our findings support a model whereby Arl8b/DENND6A/Rab34-dependent lysosomal retrograde trafficking controls autophagy.
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Affiliation(s)
- Rahul Kumar
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada.
| | - Maleeha Khan
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada
| | - Vincent Francis
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada
| | - Adriana Aguila
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada
| | - Gopinath Kulasekaran
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada
| | - Emily Banks
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute (the Neuro), McGill University, Montreal, QC, Canada.
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4
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Shen J, Liao J, Liu H, Liu C, Li C, Cheng H, Yang H, Chen H. A low-temperature digital microfluidic system used for protein-protein interaction detection. LAB ON A CHIP 2023; 23:4390-4399. [PMID: 37721054 DOI: 10.1039/d3lc00386h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
The occurrence, development and prediction of various biological processes and diseases are inseparable from the protein-protein interaction (PPI), so it is extremely meaningful to perfect PPI networks. However, shortcomings of traditional detection methods, such as protein degradation, long detection time, complex operation, poor automation and high cost, restrict the rapid development of PPI networks. Here, a low-temperature digital microfluidic (LTDMF) system-based PPI detection box (LTDMF-PPI-Box) was developed to achieve rapid, lossless and efficient PPI detection. It consists of a PMMA shell, LTDMF-PPI and an integrated temperature control system. LTDMF reduces the PPI detection time from tens of hours to 1.5 hours by programmatically controlling the movement of droplets. Moreover, an integrated thermoelectric cooler (TEC) ensures an operating temperature of 4 °C, resulting in a protein protection up to 90%. The interaction between RILP protein and Rab26 protein which has a close connection to insulin secretion was demonstrated as a prototype to illustrate the feasibility of the LTDMF-PPI-Box. LTDMF with automation characteristics is capable of meeting the requirement of high-throughput screening of interacting proteins; therefore, the LTDMF-PPI-Box is expected to accelerate the establishment of the PPI network in the future.
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Affiliation(s)
- Jienan Shen
- Center for Bionic Sensing and Intelligence, Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, P. R. China.
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, Fujian, P. R. China.
- Institute of Pediatrics, Shenzhen Children's Hospital, Shenzhen 518038, Guangdong, P. R. China
| | - Jiaqi Liao
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, Fujian, P. R. China.
| | - Huiying Liu
- The Institute of Translational Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, 330000, Jiangxi, P. R. China
| | - Chunyan Liu
- Department of Dermatology, Longgang Central Hospital, Shenzhen 518172, Guangdong, P. R. China
| | - Chonghao Li
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, Fujian, P. R. China.
| | - Hao Cheng
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, Fujian, P. R. China.
| | - Hui Yang
- Center for Bionic Sensing and Intelligence, Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, P. R. China.
| | - Hong Chen
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, Fujian, P. R. China.
- Jiujiang Research Institute of Xiamen University, Jiujiang 332000, Jiangxi, P. R. China
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5
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Cui G, Jiang Z, Chen Y, Li Y, Ai S, Sun R, Yi X, Zhong G. Evolutional insights into the interaction between Rab7 and RILP in lysosome motility. iScience 2023; 26:107040. [PMID: 37534141 PMCID: PMC10391735 DOI: 10.1016/j.isci.2023.107040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 12/12/2022] [Accepted: 06/01/2023] [Indexed: 08/04/2023] Open
Abstract
Lysosome motility is critical for the cellular function. However, Rab7-related transport elements showed genetic differences between vertebrates and invertebrates, making the mechanism of lysosomal motility mysterious. We suggested that Rab7 interacted with RILP as a feature of highly evolved organisms since they could interact with each other in Spodoptera frugiperda but not in Drosophila melanogaster. The N-terminus of Sf-RILP was identified to be necessary for their interaction, and Glu61 was supposed to be the key point for the stability of the interaction. A GC-rich domain on the C-terminal parts of Sf-RILP hampered the expression of Sf-RILP and its interaction with Sf-Rab7. Although the corresponding vital amino acids in the mammalian model at the C-terminus of Sf-RILP turned to be neutral, the C-terminus would also help with the homologous interactions between RILP fragments in insects. The significantly different interactions in invertebrates shed light on the biodiversity and complexity of lysosomal motility.
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Affiliation(s)
- Gaofeng Cui
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Silviculture, Protection and Utilization, Guangdong Academy of Forestry, Guangzhou 510520, China
| | - Zhiyan Jiang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Yaoyao Chen
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Yun Li
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Shupei Ai
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Ranran Sun
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Xin Yi
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Guohua Zhong
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
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6
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Hanoudi SN, Talwar H, Draghici S, Samavati L. Autoantibodies against cytoskeletons and lysosomal trafficking discriminate sarcoidosis from healthy controls, tuberculosis and lung cancers. MOLECULAR BIOMEDICINE 2022; 3:3. [PMID: 35048206 PMCID: PMC8770712 DOI: 10.1186/s43556-021-00064-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022] Open
Abstract
Sarcoidosis is a systemic granulomatous disease of unknown etiology. Hypergammaglobulinemia and the presence of autoantibodies in sarcoidosis suggest active humoral immunity to unknown antigen(s). We developed a complex cDNA library derived from tissues of sarcoidosis patients. Using a high throughput method, we constructed a microarray platform from this cDNA library containing large numbers of sarcoidosis clones. After selective biopanning, 1070 sarcoidosis-specifc clones were arrayed and immunoscreend with 152 sera from patients with sarcoidosis and other pulmonary diseases. To identify the sarcoidosis classifiers two statistical approaches were conducted: First, we identified significant biomarkers between sarcoidosis and healthy controls, and second identified markers comparing sarcoidosis to all other groups. At the threshold of an False Discovery Rate (FDR) < 0.01, we identified 14 clones in the first approach and 12 clones in the second approach discriminating sarcoidosis from other groups. We used the classifiers to build a naïve Bayes model on the training-set and validated it on an independent test-set. The first approach yielded an AUC of 0.947 using 14 significant clones with a sensitivity of 0.93 and specificity of 0.88, whereas the AUC of the second option was 0.92 with a sensitivity of 0.96 and specificity of 0.83. These results suggest robust classifier performance. Furthermore, we characterized the informative phage clones by sequencing and homology searches. Large numbers of classifier-clones were peptides involved in cellular trafficking and cytoskeletons. These results show that sarcoidosis is associated with a specific pattern of immunoreactivity that can discriminate it from other diseases.
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Affiliation(s)
| | - Harvinder Talwar
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Wayne State University School of Medicine, 3990 John R, 3 Hudson, Detroit, MI 48201 USA
| | - Sorin Draghici
- Department of Computer Science, Wayne State University, Detroit, MI 48202 USA
| | - Lobelia Samavati
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Wayne State University School of Medicine, 3990 John R, 3 Hudson, Detroit, MI 48201 USA
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201 USA
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7
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Sun J, Wang X, Lin H, Wan L, Chen J, Yang X, Li D, Zhang Y, He X, Wang B, Dong M, Zhong H, Wei C. Shigella escapes lysosomal degradation through inactivation of Rab31 by IpaH4.5. J Med Microbiol 2021; 70. [PMID: 34296983 DOI: 10.1099/jmm.0.001382] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Introduction. Shigella flexneri is an intracellular bacterial pathogen that utilizes a type III secretion apparatus to inject effector proteins into host cells.Hypothesis/Gap Statement. The T3SS effector IpaH4.5 is important for the virulence of Shigella.Aim. This study aimed to elucidate the molecular mechanism and host target of the IpaH4.5 as well as its roles in S. flexneri infection.Methodology. The GAP assay was used to identify substrate Rab GTPases of IpaH4.5. A coimmunoprecipitation assay was applied to identify the interaction of Rab GTPases with IpaH4.5. A confocal microscopy analysis was used to assess the effects of IpaH4.5 on mannose 6-phosphate receptor (MPR) trafficking. To identify the effects of IpaH4.5 GAP activity on the activity of lysosomal cathepsin B, the Magic Red-RR assay was used. Finally, the intracellular persistence assay was used to identify IpaH4.5 GAP activity in S. flexneri intracellular growth.Results. We found that the effector IpaH4.5 disrupts MPR trafficking and lysosomal function, thereby counteracting host lysosomal degradation. IpaH4.5 harbours TBC-like dual-finger motifs and exhibits potent RabGAP activities towards Rab31. IpaH4.5 disrupts the transport of the cation-dependent mannose 6-phosphate receptor (CD-MPR) from the Golgi to the endosome by targeting Rab31, thereby attenuating lysosomal function. As a result, the intracellular persistence of S. flexneri requires IpaH4.5 TBC-like GAP activity to mediate bacterial escape from host lysosome-mediated elimination.Conclusion. We identified an unknown function of IpaH4.5 and its potential role in S. flexneri infection.
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Affiliation(s)
- Jin Sun
- Basic Medical College, Qingdao University, Qingdao, PR China.,Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Xiaolin Wang
- Basic Medical College, Qingdao University, Qingdao, PR China.,Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Haotian Lin
- Basic Medical College, Qingdao University, Qingdao, PR China.,Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Luming Wan
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Ji Chen
- Basic Medical College, Qingdao University, Qingdao, PR China
| | - Xiaopan Yang
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Dongyu Li
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Yanhong Zhang
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Xiang He
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Bin Wang
- Basic Medical College, Qingdao University, Qingdao, PR China
| | - Mingxin Dong
- Basic Medical College, Qingdao University, Qingdao, PR China
| | - Hui Zhong
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
| | - Congwen Wei
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, PR China
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8
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Lei Z, Wang J, Zhang L, Liu CH. Ubiquitination-Dependent Regulation of Small GTPases in Membrane Trafficking: From Cell Biology to Human Diseases. Front Cell Dev Biol 2021; 9:688352. [PMID: 34277632 PMCID: PMC8281112 DOI: 10.3389/fcell.2021.688352] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/09/2021] [Indexed: 01/04/2023] Open
Abstract
Membrane trafficking is critical for cellular homeostasis, which is mainly carried out by small GTPases, a class of proteins functioning in vesicle budding, transport, tethering and fusion processes. The accurate and organized membrane trafficking relies on the proper regulation of small GTPases, which involves the conversion between GTP- and GDP-bound small GTPases mediated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Emerging evidence indicates that post-translational modifications (PTMs) of small GTPases, especially ubiquitination, play an important role in the spatio-temporal regulation of small GTPases, and the dysregulation of small GTPase ubiquitination can result in multiple human diseases. In this review, we introduce small GTPases-mediated membrane trafficking pathways and the biological processes of ubiquitination-dependent regulation of small GTPases, including the regulation of small GTPase stability, activity and localization. We then discuss the dysregulation of small GTPase ubiquitination and the associated human membrane trafficking-related diseases, focusing on the neurological diseases and infections. An in-depth understanding of the molecular mechanisms by which ubiquitination regulates small GTPases can provide novel insights into the membrane trafficking process, which knowledge is valuable for the development of more effective and specific therapeutics for membrane trafficking-related human diseases.
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Affiliation(s)
- Zehui Lei
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Jing Wang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Beijing, China
| | - Lingqiang Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing, China
| | - Cui Hua Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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9
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Oguchi ME, Homma Y, Fukuda M. The N-terminal Leu-Pro-Gln sequence of Rab34 is required for ciliogenesis in hTERT-RPE1 cells. Small GTPases 2021; 13:77-83. [PMID: 33860735 DOI: 10.1080/21541248.2021.1894910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We have previously shown that Rab34 is an important regulator of ciliogenesis and that its unique long N-terminal region (amino acids 1-49) is essential for ciliogenesis in certain cultured mammalian cells. In the present study, we performed an in-depth deletion analysis of the N-terminal region of Rab34 together with Ala-based site-directed mutagenesis to identify the essential amino acids that are required for serum-starvation-induced ciliogenesis in hTERT-RPE1 cells. The results showed that a Rab34 mutant lacking an N-terminal 18 amino acids and a Rab34 mutant carrying an LPQ-to-AAA mutation (amino acids 16-18) failed to rescue a Rab34-KO phenotype (i.e., defect in ciliogenesis). Our findings suggest that the LPQ sequence of Rab34 is crucial for ciliogenesis in hTERT-RPE1 cells.Abbreviations: AA, amino acid(s); ac-Tub, acetylated tubulin; bsr, blasticidin S-resistant gene; HRP, horseradish peroxidase; hTERT-RPE1, human telomerase reverse transcriptase retinal pigment epithelium 1; KO, knockout; NS, not significant; PBS, phosphate-buffered saline; puro, puromycin-resistant gene.
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Affiliation(s)
- Mai E Oguchi
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Yuta Homma
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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10
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Vallee RB, Yi J, Quintremil S, Khobrekar N. Roles of the multivalent dynein adaptors BicD2 and RILP in neurons. Neurosci Lett 2021; 752:135796. [PMID: 33667600 DOI: 10.1016/j.neulet.2021.135796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/18/2021] [Accepted: 02/20/2021] [Indexed: 01/18/2023]
Abstract
Cytoplasmic dynein is responsible for all forms of retrograde transport in neurons and other cells. Work over several years has led to the identification of a class of coiled-coil domain containing "adaptor" proteins that are responsible for expanding dynein's range of cargo interactions, as well as regulating dynein motor behavior. This brief review focuses first on the BicD family of adaptor proteins, which clearly serve to expand the number of dynein cargo interactions. RILP, another adaptor protein, also interacts with multiple proteins. Surprisingly, this is to mediate a series of steps within a common pathway, higher eukaryotic autophagy. These distinct features have important implications for understanding the full range of dynein adaptor functions.
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Affiliation(s)
- Richard B Vallee
- Columbia University, Department of Pathology and Cell Biology, United States
| | - Julie Yi
- Columbia University, Department of Pathology and Cell Biology, United States
| | | | - Noopur Khobrekar
- Columbia University, Department of Pathology and Cell Biology, United States.
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11
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Braun C, Hegemann JH, Mölleken K. Insights Into a Chlamydia pneumoniae-Specific Gene Cluster of Membrane Binding Proteins. Front Cell Infect Microbiol 2020; 10:565808. [PMID: 33194804 PMCID: PMC7609445 DOI: 10.3389/fcimb.2020.565808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/23/2020] [Indexed: 11/18/2022] Open
Abstract
Chlamydia pneumoniae is an obligate intracellular pathogen that causes diseases of the upper and lower respiratory tract and is linked to a number of severe and chronic conditions. Here, we describe a large, C. pneumoniae-specific cluster of 13 genes (termed mbp1-13) that encode highly homologous chlamydial proteins sharing the capacity to bind to membranes. The gene cluster is localized on the chromosome between the highly diverse adhesin-encoding pmp genes pmp15 and pmp14. Comparison of human clinical isolates to the predicted ancestral koala isolate indicates that the cluster was acquired in the ancestor and was adapted / modified during evolution. SNPs and IN/DELs within the cluster are specific to isolates taken from different human tissues and show an ongoing adaptation. Most of the cluster proteins harbor one or two domains of unknown function (DUF575 and DUF562). During ectopic expression in human cells these DUF domains are crucial for the association of cluster proteins to the endo-membrane system. Especially DUF575 which harbors a predicted transmembrane domain is important for binding to the membrane, while presence of the DUF562 seems to be of regulatory function. For Mbp1, founding member of the cluster that exhibits a very limited sequence identity to the human Rab36 protein, we found a specific binding to vesicles carrying the early endosomal marker PtdIns(3)P and the endosomal Rab GTPases Rab11 and Rab14. This binding is dependent on a predicted transmembrane domain with an α-helical / β-strand secondary structure, as the mutant version Mbp1mut, which lacks the β-strand secondary structure, shows a reduced association to PtdIns(3)P-positive membranes carrying Rab11 and Rab14. Furthermore, we could not only show that Mbp1 associates with Rab36, but found this specific Rab protein to be recruited to the early C. pneumoniae inclusion. Detection of endogenous Mbp1 and Mbp4 reveal a colocalization to the chlamydial outer membrane protein Momp on EBs. The same colocalization pattern with Momp was observed when we ectopically expressed Mbp4 in C. trachomatis. Thus, we identified a C. pneumoniae-specific cluster of 13 membrane binding proteins (Mbps) localizing to the bacterial outer membrane system.
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Affiliation(s)
- Corinna Braun
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Düsseldorf, Germany
| | - Johannes H Hegemann
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Düsseldorf, Germany
| | - Katja Mölleken
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Düsseldorf, Germany
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12
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Samarelli AV, Ziegler T, Meves A, Fässler R, Böttcher RT. Rabgap1 promotes recycling of active β1 integrins to support effective cell migration. J Cell Sci 2020; 133:jcs243683. [PMID: 32843574 PMCID: PMC7522031 DOI: 10.1242/jcs.243683] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 08/13/2020] [Indexed: 12/13/2022] Open
Abstract
Integrin function depends on the continuous internalization of integrins and their subsequent endosomal recycling to the plasma membrane to drive adhesion dynamics, cell migration and invasion. Here we assign a pivotal role for Rabgap1 (GAPCenA) in the recycling of endocytosed active β1 integrins to the plasma membrane. The phosphotyrosine-binding (PTB) domain of Rabgap1 binds to the membrane-proximal NPxY motif in the cytoplasmic domain of β1 integrin subunits on endosomes. Silencing Rabgap1 in mouse fibroblasts leads to the intracellular accumulation of active β1 integrins, alters focal adhesion formation, and decreases cell migration and cancer cell invasion. Functionally, Rabgap1 facilitates active β1 integrin recycling to the plasma membrane through attenuation of Rab11 activity. Taken together, our results identify Rabgap1 as an important factor for conformation-specific integrin trafficking and define the role of Rabgap1 in β1-integrin-mediated cell migration in mouse fibroblasts and breast cancer cells.
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Affiliation(s)
- Anna V Samarelli
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
| | - Tilman Ziegler
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
| | - Alexander Meves
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
- Department of Dermatology, Mayo Clinic, Rochester, MN 55905, USA
| | - Reinhard Fässler
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
| | - Ralph T Böttcher
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
- DZHK - German Centre for Cardiovascular Research, partner site Munich Heart Alliance, 80802 Munich, Germany
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Sanyal A, Novis HS, Gasser E, Lin S, LaVoie MJ. LRRK2 Kinase Inhibition Rescues Deficits in Lysosome Function Due to Heterozygous GBA1 Expression in Human iPSC-Derived Neurons. Front Neurosci 2020; 14:442. [PMID: 32499675 PMCID: PMC7243441 DOI: 10.3389/fnins.2020.00442] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 04/09/2020] [Indexed: 12/22/2022] Open
Abstract
A growing number of genes associated with Parkinson’s disease are implicated in the regulation of lysosome function, including LRRK2, whose missense mutations are perhaps the most common monogenic cause of this neurodegenerative disease. These mutations are collectively thought to introduce a pathologic increase in LRRK2 kinase activity, which is currently a major target for therapeutic intervention. Heterozygous carriers of many missense mutations in the GBA1 gene have dramatically increased risk of Parkinson’s disease. A critical question has recently emerged regarding the potential interplay between the proteins encoded by these two disease-linked genes. Our group has recently demonstrated that knockin mutation of a Parkinson’s-linked GBA1 variant induces severe lysosomal and cytokine abnormalities in murine astrocytes and that these deficits were normalized via inhibition of wild-type LRRK2 kinase activity in these cells. Another group independently found that LRRK2 inhibition increases glucocerebrosidase activity in wild-type human iPSC-derived neurons, as well as those whose activity is disrupted by GBA1 or LRRK2 mutation. Fundamental questions remain in terms of the lysosomal abnormalities and the effects of LRRK2 kinase inhibition in human neurons deficient in glucocerebrosidase activity. Here, we further elucidate the physiological crosstalk between LRRK2 signaling and glucocerebrosidase activity in human iPSC-derived neurons. Our studies show that the allelic loss of GBA1 manifests broad defects in lysosomal morphology and function. Furthermore, our data show an increase in both the accumulation and secretion of oligomeric α-synuclein protein in these GBA1-heterozygous-null neurons, compared to isogenic controls. Consistent with recent findings in murine astrocytes, we observed that multiple indices of lysosomal dysfunction in GBA1-deficient human neurons were normalized by LRRK2 kinase inhibition, while some defects were preserved. Our findings demonstrate a selective but functional intersection between glucocerebrosidase dysfunction and LRRK2 signaling in the cell and may have implications in the pathogenesis and treatment of Parkinson’s disease.
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Affiliation(s)
- Anwesha Sanyal
- Ann Romney Center for Neurological Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Hailey S Novis
- Ann Romney Center for Neurological Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Emile Gasser
- Ann Romney Center for Neurological Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Steven Lin
- Ann Romney Center for Neurological Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Matthew J LaVoie
- Ann Romney Center for Neurological Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
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de Martín Garrido N, Aylett CHS. Nutrient Signaling and Lysosome Positioning Crosstalk Through a Multifunctional Protein, Folliculin. Front Cell Dev Biol 2020; 8:108. [PMID: 32195250 PMCID: PMC7063858 DOI: 10.3389/fcell.2020.00108] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 02/10/2020] [Indexed: 12/16/2022] Open
Abstract
FLCN was identified as the gene responsible for Birt-Hogg-Dubé (BHD) syndrome, a hereditary syndrome associated with the appearance of familiar renal oncocytomas. Most mutations affecting FLCN result in the truncation of the protein, and therefore loss of its associated functions, as typical for a tumor suppressor. FLCN encodes the protein folliculin (FLCN), which is involved in numerous biological processes; mutations affecting this protein thus lead to different phenotypes depending on the cellular context. FLCN forms complexes with two large interacting proteins, FNIP1 and FNIP2. Structural studies have shown that both FLCN and FNIPs contain longin and differentially expressed in normal versus neoplastic cells (DENN) domains, typically involved in the regulation of small GTPases. Accordingly, functional studies show that FLCN regulates both the Rag and the Rab GTPases depending on nutrient availability, which are respectively involved in the mTORC1 pathway and lysosomal positioning. Although recent structural studies shed light on the precise mechanism by which FLCN regulates the Rag GTPases, which in turn regulate mTORC1, how FLCN regulates membrane trafficking through the Rab GTPases or the significance of the intriguing FLCN-FNIP-AMPK complex formation are questions that still remain unanswered. We discuss the recent progress in our understanding of FLCN regulation of both growth signaling and lysosomal positioning, as well as future approaches to establish detailed mechanisms to explain the disparate phenotypes caused by the loss of FLCN function and the development of BHD-associated and other tumors.
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Affiliation(s)
| | - Christopher H. S. Aylett
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
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15
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Zhou Y, Liu Z, Zhang S, Zhuang R, Liu H, Liu X, Qiu X, Zhang M, Zheng Y, Li L, Hong W, Wang T. RILP Restricts Insulin Secretion Through Mediating Lysosomal Degradation of Proinsulin. Diabetes 2020; 69:67-82. [PMID: 31624142 DOI: 10.2337/db19-0086] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 10/06/2019] [Indexed: 11/13/2022]
Abstract
Insulin secretion is tightly regulated by membrane trafficking. RILP (Rab7 interacting lysosomal protein) regulates the endocytic trafficking, but its role in insulin secretion has not been investigated. In this study, we found that overexpression of RILP inhibited insulin secretion in both the β-cell lines and freshly isolated islets. Consequently, the expression of RILP in islets suppressed the ability to recover the glucose homeostasis in type 1 diabetes mice upon transplantation. Of physiological relevance is that RILP expression was upregulated in the diabetic mouse islets. Mechanistically, overexpression of RILP induced insulin granule clustering, decreased the number of proinsulin-containing granules in β-cells, and significantly promoted proinsulin degradation. Conversely, RILP depletion sustained proinsulin and increased insulin secretion. The proinsulin degradation induced by RILP expression was inhibited by lysosomal inhibitors and was Rab7-dependent. Finally, we showed that RILP interacts with insulin granule-associated Rab26 to restrict insulin secretion. This study presents a new pathway regulating insulin secretion and mechanically demonstrates a novel function of RILP in modulating insulin secretion through mediating the lysosomal degradation of proinsulin.
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Affiliation(s)
- Yuxia Zhou
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Zhiyu Liu
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Shengmei Zhang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Ruijuan Zhuang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Huiying Liu
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Xiaoqing Liu
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Xi Qiu
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Ming Zhang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Yanpan Zheng
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Liangcheng Li
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
| | - Wanjin Hong
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
- Institute of Molecular and Cell Biology, A STAR (Agency of Science, Technology and Research), Singapore, Singapore
| | - Tuanlao Wang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Fujian, China
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16
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Coppola U, Ristoratore F, Albalat R, D'Aniello S. The evolutionary landscape of the Rab family in chordates. Cell Mol Life Sci 2019; 76:4117-4130. [PMID: 31028425 PMCID: PMC11105323 DOI: 10.1007/s00018-019-03103-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/29/2019] [Accepted: 04/10/2019] [Indexed: 12/30/2022]
Abstract
Intracellular traffic amongst organelles represents a key feature for eukaryotes and is orchestrated principally by members of Rab family, the largest within Ras superfamily. Given that variations in Rab repertoire have been fundamental in animal diversification, we provided the most exhaustive survey regarding the Rab toolkit of chordates. Our findings reveal the existence of 42 metazoan conserved subfamilies exhibiting a univocal intron/exon structure preserved from cnidarians to vertebrates. Since the current view does not capture the Rab complexity, we propose a new Rab family classification in three distinct monophyletic clades. The Rab complement of chordates shows a dramatic diversification due to genome duplications and independent gene duplications and losses with sharp differences amongst cephalochordates, tunicates and gnathostome vertebrates. Strikingly, the analysis of the domain architecture of this family highlighted the existence of chimeric calcium-binding Rabs, which are animal novelties characterized by a complex evolutionary history in gnathostomes and whose role in cellular metabolism is obscure. This work provides novel insights in the knowledge of Rab family: our hypothesis is that chordates represent a hotspot of Rab variability, with many events of gene gains and losses impacting intracellular traffic capabilities. Our results help to elucidate the role of Rab members in the transport amongst endomembranes and shed light on intracellular traffic routes in vertebrates. Then, since the predominant role of Rabs in the molecular communication between different cellular districts, this study paves to way to comprehend inherited or acquired human disorders provoked by dysfunctions in Rab genes.
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Affiliation(s)
- Ugo Coppola
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Napoli, Villa Comunale 1, 80121, Naples, Italy
- Molecular Cardiovascular Biology Division, Cincinnati Children's Hospital Medical Center, Cincinnati, USA
| | - Filomena Ristoratore
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Napoli, Villa Comunale 1, 80121, Naples, Italy
| | - Ricard Albalat
- Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| | - Salvatore D'Aniello
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Napoli, Villa Comunale 1, 80121, Naples, Italy.
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D'Souza Z, Blackburn JB, Kudlyk T, Pokrovskaya ID, Lupashin VV. Defects in COG-Mediated Golgi Trafficking Alter Endo-Lysosomal System in Human Cells. Front Cell Dev Biol 2019; 7:118. [PMID: 31334232 PMCID: PMC6616090 DOI: 10.3389/fcell.2019.00118] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 06/11/2019] [Indexed: 12/27/2022] Open
Abstract
The conserved oligomeric complex (COG) is a multi-subunit vesicle tethering complex that functions in retrograde trafficking at the Golgi. We have previously demonstrated that the formation of enlarged endo-lysosomal structures (EELSs) is one of the major glycosylation-independent phenotypes of cells depleted for individual COG complex subunits. Here, we characterize the EELSs in HEK293T cells using microscopy and biochemical approaches. Our analysis revealed that the EELSs are highly acidic and that vATPase-dependent acidification is essential for the maintenance of this enlarged compartment. The EELSs are accessible to both trans-Golgi enzymes and endocytic cargo. Moreover, the EELSs specifically accumulate endolysosomal proteins Lamp2, CD63, Rab7, Rab9, Rab39, Vamp7, and STX8 on their surface. The EELSs are distinct from lysosomes and do not accumulate active Cathepsin B. Retention using selective hooks (RUSH) experiments revealed that biosynthetic cargo mCherry-Lamp1 reaches the EELSs much faster as compared to both receptor-mediated and soluble endocytic cargo, indicating TGN origin of the EELSs. In support to this hypothesis, EELSs are enriched with TGN specific lipid PI4P. Additionally, analysis of COG4/VPS54 double KO cells revealed that the activity of the GARP tethering complex is necessary for EELSs’ accumulation, indicating that protein mistargeting and the imbalance of Golgi-endosome membrane flow leads to the formation of EELSs in COG-deficient cells. The EELSs are likely to serve as a degradative storage hybrid organelle for mistargeted Golgi enzymes and underglycosylated glycoconjugates. To our knowledge this is the first report of the formation of an enlarged hybrid endosomal compartment in a response to malfunction of the intra-Golgi trafficking machinery.
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Affiliation(s)
- Zinia D'Souza
- Department of Physiology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Jessica Bailey Blackburn
- Department of Physiology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Tetyana Kudlyk
- Department of Physiology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Irina D Pokrovskaya
- Department of Physiology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Vladimir V Lupashin
- Department of Physiology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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18
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Cao QJ, Zhang N, Zhou R, Yao LL, Li XD. The cargo adaptor proteins RILPL2 and melanophilin co-regulate myosin-5a motor activity. J Biol Chem 2019; 294:11333-11341. [PMID: 31175157 DOI: 10.1074/jbc.ra119.007384] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 06/03/2019] [Indexed: 11/06/2022] Open
Abstract
Vertebrate myosin-5a is an ATP-utilizing processive motor associated with the actin network and responsible for the transport and localization of several vesicle cargoes. To transport cargo efficiently and prevent futile ATP hydrolysis, myosin-5a motor function must be tightly regulated. The globular tail domain (GTD) of myosin-5a not only functions as the inhibitory domain but also serves as the binding site for a number of cargo adaptor proteins, including melanophilin (Mlph) and Rab-interacting lysosomal protein-like 2 (RILPL2). In this study, using various biochemical approaches, including ATPase, single-molecule motility, GST pulldown assays, and analytical ultracentrifugation, we demonstrate that the binding of both Mlph and RILPL2 to the GTD of myosin-5a is required for the activation of myosin-5a motor function under physiological ionic conditions. We also found that this activation is regulated by the small GTPase Rab36, a binding partner of RILPL2. In summary, our results indicate that RILPL2 is required for Mlph-mediated activation of Myo5a motor activity under physiological conditions and that Rab36 promotes this activation. We propose that Rab36 stimulates RILPL2 to interact with the myosin-5a GTD; this interaction then induces exposure of the Mlph-binding site in the GTD, enabling Mlph to interact with the GTD and activate myosin-5a motor activity.
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Affiliation(s)
- Qing-Juan Cao
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ning Zhang
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Rui Zhou
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lin-Lin Yao
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiang-Dong Li
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China .,University of Chinese Academy of Sciences, Beijing 100049, China
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19
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Zhang X, Huang TY, Yancey J, Luo H, Zhang YW. Role of Rab GTPases in Alzheimer's Disease. ACS Chem Neurosci 2019; 10:828-838. [PMID: 30261139 DOI: 10.1021/acschemneuro.8b00387] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) comprises two major pathological hallmarks: extraneuronal deposition of β-amyloid (Aβ) peptides ("senile plaques") and intraneuronal aggregation of the microtubule-associated protein tau ("neurofibrillary tangles"). Aβ is derived from sequential cleavage of the β-amyloid precursor protein by β- and γ-secretases, while aggregated tau is hyperphosphorylated in AD. Mounting evidence suggests that dysregulated trafficking of these AD-related proteins contributes to AD pathogenesis. Rab proteins are small GTPases that function as master regulators of vesicular transport and membrane trafficking. Multiple Rab GTPases have been implicated in AD-related protein trafficking, and their expression has been observed to be altered in postmortem AD brain. Here we review current implicated roles of Rab GTPase dysregulation in AD pathogenesis. Further elucidation of the pathophysiological role of Rab GTPases will likely reveal novel targets for AD therapeutics.
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Affiliation(s)
- Xian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College of Xiamen University, Xiamen, Fujian 361102, China
| | - Timothy Y. Huang
- Neuroscience Initiative, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Joel Yancey
- Neuroscience Initiative, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Hong Luo
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College of Xiamen University, Xiamen, Fujian 361102, China
| | - Yun-wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College of Xiamen University, Xiamen, Fujian 361102, China
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Abstract
The Golgi apparatus is a central sorting station in the cell. It receives newly synthesized molecules from the endoplasmic reticulum and directs them to different subcellular destinations, such as the plasma membrane or the endocytic pathway. Importantly, in the last few years, it has emerged that the maintenance of Golgi structure is connected to the proper regulation of membrane trafficking. Rab proteins are small GTPases that are considered to be the master regulators of the intracellular membrane trafficking. Several of the over 60 human Rabs are involved in the regulation of transport pathways at the Golgi as well as in the maintenance of its architecture. This chapter will summarize the different roles of Rab GTPases at the Golgi, both as regulators of membrane transport, scaffold, and tethering proteins and in preserving the structure and function of this organelle.
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21
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Inhibition of miR-1247 on cell proliferation and invasion in bladder cancer through its downstream target of RAB36. J Biosci 2018. [DOI: 10.1007/s12038-018-9755-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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22
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2018. [PMID: 29239692 DOI: 10.1080/215412481397833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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23
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2017; 9:158-181. [PMID: 29239692 DOI: 10.1080/21541248.2017.1397833] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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24
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Willett R, Martina JA, Zewe JP, Wills R, Hammond GRV, Puertollano R. TFEB regulates lysosomal positioning by modulating TMEM55B expression and JIP4 recruitment to lysosomes. Nat Commun 2017; 8:1580. [PMID: 29146937 PMCID: PMC5691037 DOI: 10.1038/s41467-017-01871-z] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/20/2017] [Indexed: 12/27/2022] Open
Abstract
Lysosomal distribution is linked to the role of lysosomes in many cellular functions, including autophagosome degradation, cholesterol homeostasis, antigen presentation, and cell invasion. Alterations in lysosomal positioning contribute to different human pathologies, such as cancer, neurodegeneration, and lysosomal storage diseases. Here we report the identification of a novel mechanism of lysosomal trafficking regulation. We found that the lysosomal transmembrane protein TMEM55B recruits JIP4 to the lysosomal surface, inducing dynein-dependent transport of lysosomes toward the microtubules minus-end. TMEM55B overexpression causes lysosomes to collapse into the cell center, whereas depletion of either TMEM55B or JIP4 results in dispersion toward the cell periphery. TMEM55B levels are transcriptionally upregulated following TFEB and TFE3 activation by starvation or cholesterol-induced lysosomal stress. TMEM55B or JIP4 depletion abolishes starvation-induced retrograde lysosomal transport and prevents autophagosome-lysosome fusion. Overall our data suggest that the TFEB/TMEM55B/JIP4 pathway coordinates lysosome movement in response to a variety of stress conditions.
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Affiliation(s)
- Rose Willett
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD, 20892, USA
| | - José A Martina
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD, 20892, USA
| | - James P Zewe
- Department of Cell Biology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Room S332 Biomedical Sciences Tower, Pittsburgh, PA, 15213, USA
| | - Rachel Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Room S332 Biomedical Sciences Tower, Pittsburgh, PA, 15213, USA
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Room S332 Biomedical Sciences Tower, Pittsburgh, PA, 15213, USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD, 20892, USA.
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25
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Mudigoudar B, Nune S, Fulton S, Dayyat E, Wheless JW. Epilepsy in 22q11.2 Deletion Syndrome: A Case Series and Literature Review. Pediatr Neurol 2017; 76:86-90. [PMID: 28969878 DOI: 10.1016/j.pediatrneurol.2017.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 08/10/2017] [Accepted: 08/19/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND The 22q11.2 deletion syndrome affects multiple organ systems, and the neurological manifestations are an important aspect of this disorder. Many are aware of cardiac anomalies associated with this uncommon genetic disorder. However, the different types of seizures, electroencephalography (EEG), and brain magnetic resonance imaging (MRI) findings seen in this condition are not appreciated. METHODS Medical records of four patients with epilepsy due to 22q11.2 deletion syndrome were retrospectively reviewed for documentation of seizure types, EEG, and brain MRI findings. In addition, we also did a literature review of previously reported individuals with unprovoked seizures in this condition. RESULTS A review of all published cases including our patients reveals that focal epilepsy (39 of 88, 44%) is the most common type followed by genetic generalized epilepsy (24 of 88, 27%). Diffuse cerebral atrophy and polymicrogyria were the most frequent MRI findings. CONCLUSIONS Patients with structural brain abnormalities, especially polymicrogyria and associated epilepsy should have a chromosomal microarray (CMA) performed to screen for the 22q11.2 deletion syndrome. Focal epilepsy and genetic generalized epilepsy are the most frequent epilepsy types reported in this condition.
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Affiliation(s)
- Basanagoud Mudigoudar
- Department of Pediatrics, Division of Pediatric Neurology, University of Tennessee Health Science Center, Memphis, Tennessee; Neuroscience Institute & Le Bonheur Comprehensive Epilepsy Program, Le Bonheur Children's Hospital, Memphis, Tennessee.
| | - Sunitha Nune
- Department of Neurology, University of Michigan, Ann Arbor, Michigan
| | - Stephen Fulton
- Department of Pediatrics, Division of Pediatric Neurology, University of Tennessee Health Science Center, Memphis, Tennessee; Neuroscience Institute & Le Bonheur Comprehensive Epilepsy Program, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - Ehab Dayyat
- Department of Pediatrics, Division of Pediatric Neurology, University of Tennessee Health Science Center, Memphis, Tennessee; Neuroscience Institute & Le Bonheur Comprehensive Epilepsy Program, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - James W Wheless
- Department of Pediatrics, Division of Pediatric Neurology, University of Tennessee Health Science Center, Memphis, Tennessee; Neuroscience Institute & Le Bonheur Comprehensive Epilepsy Program, Le Bonheur Children's Hospital, Memphis, Tennessee
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26
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Golgi trafficking defects in postnatal microcephaly: The evidence for “Golgipathies”. Prog Neurobiol 2017; 153:46-63. [DOI: 10.1016/j.pneurobio.2017.03.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/22/2017] [Accepted: 03/29/2017] [Indexed: 12/17/2022]
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27
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Dodding MP. Folliculin - A tumor suppressor at the intersection of metabolic signaling and membrane traffic. Small GTPases 2016; 8:100-105. [PMID: 27355777 DOI: 10.1080/21541248.2016.1204808] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The Birt-Hoge-Dubé syndrome tumor suppressor Folliculin is a regulator of metabolism and has as a wide range of cellular and organismal phenotypes associated with its disruption. However, the molecular mechanisms which underlie its functions are poorly understood. Folliculin has been described to associate with lysosomes in response to nutrient depletion and form a key part of the signaling network that controls the activity of mTORC1. We recently reported that Folliculin can control the nutrient dependent cytoplasmic distribution of lysosomes by promoting the formation of a complex with the Golgi-associated small GTPase Rab34 and its effector RILP. We thus define a mechanistic connection between the lysosomal nutrient signaling network and the transport machinery that controls the distribution and dynamics of this organelle. Here we summarise the main conclusions from that study, attempt to integrate our findings with other recent studies on lysosome distribution/dynamics, and discuss the potential consequences of the dysregulation of this processes caused by Folliculin loss for Birt-Hoge-Dubé syndrome and normal cell function.
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Affiliation(s)
- Mark P Dodding
- a Randall Division of Cell and Molecular Biophysics , King's College London , London , UK
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28
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Starling GP, Yip YY, Sanger A, Morton PE, Eden ER, Dodding MP. Folliculin directs the formation of a Rab34-RILP complex to control the nutrient-dependent dynamic distribution of lysosomes. EMBO Rep 2016; 17:823-41. [PMID: 27113757 PMCID: PMC4893818 DOI: 10.15252/embr.201541382] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 03/14/2016] [Indexed: 11/09/2022] Open
Abstract
The spatial distribution of lysosomes is important for their function and is, in part, controlled by cellular nutrient status. Here, we show that the lysosome associated Birt-Hoge-Dubé (BHD) syndrome renal tumour suppressor folliculin (FLCN) regulates this process. FLCN promotes the peri-nuclear clustering of lysosomes following serum and amino acid withdrawal and is supported by the predominantly Golgi-associated small GTPase Rab34. Rab34-positive peri-nuclear membranes contact lysosomes and cause a reduction in lysosome motility and knockdown of FLCN inhibits Rab34-induced peri-nuclear lysosome clustering. FLCN interacts directly via its C-terminal DENN domain with the Rab34 effector RILP Using purified recombinant proteins, we show that the FLCN-DENN domain does not act as a GEF for Rab34, but rather, loads active Rab34 onto RILP We propose a model whereby starvation-induced FLCN association with lysosomes drives the formation of contact sites between lysosomes and Rab34-positive peri-nuclear membranes that restrict lysosome motility and thus promote their retention in this region of the cell.
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Affiliation(s)
- Georgina P Starling
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Yan Y Yip
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Anneri Sanger
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Penny E Morton
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Emily R Eden
- Institute of Ophthalmology, University College London, London, UK
| | - Mark P Dodding
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
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29
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Hämälistö S, Jäättelä M. Lysosomes in cancer-living on the edge (of the cell). Curr Opin Cell Biol 2016; 39:69-76. [PMID: 26921697 DOI: 10.1016/j.ceb.2016.02.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 12/25/2022]
Abstract
The lysosomes have definitely polished their status inside the cell. Being discovered as the last resort of discarded cellular biomass, the steady rising of this versatile signaling organelle is currently ongoing. This review discusses the recent data on the unconventional functions of lysosomes, focusing mainly on the less studied lysosomes residing in the cellular periphery. We emphasize our discussion on the emerging paths the lysosomes have taken in promoting cancer progression to metastatic disease. Finally, we address how the altered cancerous lysosomes in metastatic cancers may be specifically targeted and what are the pending questions awaiting for elucidation.
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Affiliation(s)
- Saara Hämälistö
- Cell Death and Metabolism Unit, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Marja Jäättelä
- Cell Death and Metabolism Unit, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, Copenhagen, Denmark.
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30
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Efergan A, Azouz NP, Klein O, Noguchi K, Rothenberg ME, Fukuda M, Sagi-Eisenberg R. Rab12 Regulates Retrograde Transport of Mast Cell Secretory Granules by Interacting with the RILP-Dynein Complex. THE JOURNAL OF IMMUNOLOGY 2016; 196:1091-101. [PMID: 26740112 DOI: 10.4049/jimmunol.1500731] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 11/20/2015] [Indexed: 12/19/2022]
Abstract
Secretory granule (SG) transport is a critical step in regulated exocytosis including degranulation of activated mast cells. The latter process results in the release of multiple inflammatory mediators that play key roles in innate immunity, as well as in allergic responses. In this study, we identified the small GTPase Rab12 as a novel regulator of mast cell SG transport, and we provide mechanistic insights into its mode of action. We show that Rab12 is activated in a stimulus-dependent fashion and promotes microtubule-dependent retrograde transport of the SGs in the activated cells. We also show that this minus end transport of the SGs is mediated by the RILP-dynein complex and identify RILP as a novel effector of Rab12. Finally, we show that Rab12 negatively regulates mast cell degranulation. Taken together, our results identify Rab12 as a novel regulator of mast cell responses and disclose for the first time, to our knowledge, the mechanism of retrograde transport of the mast cell SGs.
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Affiliation(s)
- Adi Efergan
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nurit P Azouz
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ofir Klein
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Kenta Noguchi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan; and
| | - Marc E Rothenberg
- Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan; and
| | - Ronit Sagi-Eisenberg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel;
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31
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RILP interacts with HOPS complex via VPS41 subunit to regulate endocytic trafficking. Sci Rep 2014; 4:7282. [PMID: 25445562 PMCID: PMC4250914 DOI: 10.1038/srep07282] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 11/13/2014] [Indexed: 11/30/2022] Open
Abstract
The HOPS complex serves as a tethering complex with GEF activity for Ypt7p in yeast to regulate late endosomal membrane maturation. While the role of HOPS complex is well established in yeast cells, its functional and mechanistic aspects in mammalian cells are less well defined. In this study, we report that RILP, a downstream effector of Rab7, interacts with HOPS complex and recruits HOPS subunits to the late endosomal compartment. Structurally, the amino-terminal portion of RILP interacts with HOPS complex. Unexpectedly, this interaction is independent of Rab7. VPS41 subunit of HOPS complex was defined to be the major partner for interacting with RILP. The carboxyl-terminal region of VPS41 was mapped to be responsible for the interaction. Functionally, either depletion of VPS41 by shRNA or overexpression of VPS41 C-terminal half retarded EGF-induced degradation of EGFR. These results suggest that interaction of RILP with HOPS complex via VPS41 plays a role in endocytic trafficking of EGFR.
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32
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Wang S, Ma Z, Xu X, Wang Z, Sun L, Zhou Y, Lin X, Hong W, Wang T. A role of Rab29 in the integrity of the trans-Golgi network and retrograde trafficking of mannose-6-phosphate receptor. PLoS One 2014; 9:e96242. [PMID: 24788816 PMCID: PMC4008501 DOI: 10.1371/journal.pone.0096242] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 04/07/2014] [Indexed: 11/18/2022] Open
Abstract
Rab29 (also referred as Rab7L1) is a novel Rab protein, and is recently demonstrated to regulate phagocytosis and traffic from the Golgi to the lysosome. However, its roles in membrane trafficking have not been investigated extensively. Our results in this study revealed that Rab29 is associated with the trans-Golgi network (TGN), and is essential for maintaining the integrity of the TGN, because inhibition of the activity of Rab29 or depletion of Rab29 resulted in fragmentation of the TGN marked by TGN46. Expression of the dominant negative form Rab29T21N or shRNA-Rab29 also altered the distribution of mannose-6-phosphate receptor (M6PR), and interrupted the retrograde trafficking of M6PR through monitoring the endocytosis of CD8-tagged calcium dependent M6PR (cdM6PR) or calcium independent M6PR (ciM6PR), but without significant effects on the anterograde trafficking of vesicular stomatitis virus G protein (VSV-G). Our results suggest that Rab29 is essential for the integrity of the TGN and participates in the retrograde trafficking of M6PRs.
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Affiliation(s)
- Shicong Wang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Zexu Ma
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Xiaohui Xu
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Zhen Wang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Lixiang Sun
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Yunhe Zhou
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Xiaosi Lin
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
| | - Wanjin Hong
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Tuanlao Wang
- School of Pharmaceutical Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, Fujian, China
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33
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Jin RU, Mills JC. RAB26 coordinates lysosome traffic and mitochondrial localization. J Cell Sci 2014; 127:1018-32. [PMID: 24413166 PMCID: PMC3937772 DOI: 10.1242/jcs.138776] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 12/04/2013] [Indexed: 12/29/2022] Open
Abstract
As they mature, professional secretory cells like pancreatic acinar and gastric chief cells induce the transcription factor MIST1 (also known as BHLHA15) to substantially scale up production of large secretory granules in a process that involves expansion of apical cytoplasm and redistribution of lysosomes and mitochondria. How a scaling factor like MIST1 rearranges cellular architecture simply by regulating expression levels of its transcriptional targets is unknown. RAB26 is a MIST1 target whose role in MIST1-mediated secretory cell maturation is also unknown. Here, we confirm that RAB26 expression, unlike most Rabs which are ubiquitously expressed, is tissue specific and largely confined to MIST1-expressing secretory tissues. Surprisingly, functional studies showed that RAB26 predominantly associated with LAMP1/cathepsin D lysosomes and not directly with secretory granules. Moreover, increasing RAB26 expression - by inducing differentiation of zymogen-secreting cells or by direct transfection - caused lysosomes to coalesce in a central, perinuclear region. Lysosome clustering in turn caused redistribution of mitochondria into distinct subcellular neighborhoods. The data elucidate a novel function for RAB26 and suggest a mechanism for how cells could increase transcription of key effectors to reorganize subcellular compartments during differentiation.
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Affiliation(s)
- Ramon U. Jin
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jason C. Mills
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
- Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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34
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Neefjes J, van der Kant R. Stuck in traffic: an emerging theme in diseases of the nervous system. Trends Neurosci 2014; 37:66-76. [PMID: 24411104 DOI: 10.1016/j.tins.2013.11.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/25/2013] [Accepted: 11/27/2013] [Indexed: 12/11/2022]
Abstract
The past decade has seen an explosion of DNA sequencing activities and many mutations and genetic variances underlying neurological and neurodegenerative diseases have been determined. This wealth of genetic data is now placed in molecular pathways revealing the nodes that underlie the disrupted processes. Many mutations in neurological diseases affect proteins controlling endosomal/lysosomal transport. Although the age of onset of these diseases range from juvenile [i.e., Niemann-Pick type C (NPC) and Charcot-Marie-Tooth (CMT) disease] to late onset (Parkinson's and Alzheimer's disease), deregulation of endosomal transport is a common theme. This review summarizes how elucidating the genetic basis for the various neurological diseases has advanced our understanding of the endo-lysosomal system and why the various mutations all translate into similar disease phenotypes.
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Affiliation(s)
- Jacques Neefjes
- Division of Cell Biology, Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands.
| | - Rik van der Kant
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA.
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35
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Piccione M, Vecchio D, Salzano E, Corsello G. Delineating a new critical region for juvenile myoclonic epilepsy at the 22q11.2 chromosome. Epilepsy Behav 2013; 29:587-8. [PMID: 24012507 DOI: 10.1016/j.yebeh.2013.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 08/09/2013] [Indexed: 01/01/2023]
Affiliation(s)
- Maria Piccione
- Department of Sciences for Health Promotion and Mother and Child Care, University of Palermo, Palermo, Italy.
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36
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Kasmapour B, Cai L, Gutierrez MG. Spatial distribution of phagolysosomes is independent of the regulation of lysosome position by Rab34. Int J Biochem Cell Biol 2013; 45:2057-65. [PMID: 23871933 DOI: 10.1016/j.biocel.2013.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 07/05/2013] [Accepted: 07/09/2013] [Indexed: 11/20/2022]
Abstract
Within a cell, the regulation of organelle positioning is considered to be critical in spatio-temporal responses. The position of late endocytic organelles (named here lysosomes for simplicity) is tightly controlled and has a functional impact on processes like endocytosis, phagocytosis and autophagocytosis. The cytoplasmic distribution profile of lysosomes can be easily determined in cells where the cytoplasm/nuclear ratio in a cross-section area is high. However, determining lysosomal position in cells with lower cytoplasm/nuclear ratio, such as macrophages is more challenging. Here, we describe a method that can be efficiently and accurately used to determine the position of organelles in macrophages using confocal microscopy in two-dimensional (2D) images. Using this approach in macrophages, we confirmed previous observations in epithelial cells that both changes in cytoplasmic pH and the levels of active Rab34 induced a re-distribution of lysosomes to the cell centre or periphery. Noteworthy is that this Rab34-dependent re-distribution of lysosomes did not significantly affect the spatial distribution profile of phagolysosomes in the cytoplasm. We conclude that although Rab34 regulates both lysosomal positioning and lysosome to phagosome fusion, the latter effect is not due to the regulation of the cytoplasmic accessibility of lysosomes to phagosomes by Rab34.
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Affiliation(s)
- Bahram Kasmapour
- Research Group Phagosome Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
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37
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Schaub JR, Stearns T. The Rilp-like proteins Rilpl1 and Rilpl2 regulate ciliary membrane content. Mol Biol Cell 2012; 24:453-64. [PMID: 23264467 PMCID: PMC3571868 DOI: 10.1091/mbc.e12-08-0598] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The Rilp-like proteins Rilpl1 and Rilpl2 are novel centrosomal and ciliary proteins. Depletion of Rilp-like proteins leads to the accumulation of signaling proteins in the cilium and disruption of epithelial cell organization, suggesting that Rilpl1 and Rilpl2 regulate ciliary membrane content by promoting protein removal. The primary cilium is a microtubule-based structure found in most cell types in mammals. Disruption of cilium function causes a diverse set of human diseases collectively known as ciliopathies. We report that Rab effector–related proteins Rab-interacting lysosomal protein-like 1 (Rilpl1) and Rilpl2 regulate protein localization in the primary cilium. Rilpl2 was initially identified as up-regulated in ciliating mouse tracheal epithelial cells. Rilpl1 and Rilpl2 both localize to the primary cilium and centrosome, Rilpl1 specifically to the distal end of the mother centriole. Live-cell microscopy reveals that Rilpl2 primary cilium localization is dynamic and that it is associated with tubulovesicular structures at the base of the cilium. Depletion of Rilpl1 and Rilpl2 results in accumulation of signaling proteins in the ciliary membrane and prevents proper epithelial cell organization in three-dimensional culture. These data suggest that Rilp-like proteins function in regulation of ciliary membrane protein concentration by promoting protein removal from the primary cilium.
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Affiliation(s)
- Johanna R Schaub
- Department of Biology, Stanford University, Department of Genetics, Stanford School of Medicine, Stanford, CA 94305, USA
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38
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Matsui T, Ohbayashi N, Fukuda M. The Rab interacting lysosomal protein (RILP) homology domain functions as a novel effector domain for small GTPase Rab36: Rab36 regulates retrograde melanosome transport in melanocytes. J Biol Chem 2012; 287:28619-31. [PMID: 22740695 DOI: 10.1074/jbc.m112.370544] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Small GTPase Rab functions as a molecular switch that drives membrane trafficking through specific interaction with its effector molecule. Thus, identification of its specific effector domain is crucial to revealing the molecular mechanism that underlies Rab-mediated membrane trafficking. Because of the large numbers of Rab isoforms in higher eukaryotes, however, the effector domains of most of the vertebrate- or mammalian-specific Rabs have yet to be determined. In this study we screened for effector molecules of Rab36, a previously uncharacterized Rab isoform that is largely conserved in vertebrates, and we succeeded in identifying nine Rab36-binding proteins, including RILP (Rab interacting lysosomal protein) family members. Sequence comparison revealed that five of nine Rab36-binding proteins, i.e. RILP, RILP-L1, RILP-L2, and JIP3/4, contain a conserved coiled-coil domain. We identified the coiled-coil domain as a RILP homology domain (RHD) and characterized it as a common Rab36-binding site. Site-directed mutagenesis of the RHD of RILP revealed the different contributions by amino acids in the RHD to binding activity toward Rab7 and Rab36. Expression of RILP in melanocytes, but not expression of its Rab36 binding-deficient mutants, induced perinuclear aggregation of melanosomes, and this effect was clearly attenuated by knockdown of endogenous Rab36 protein. Moreover, knockdown of Rab36 in Rab27A-deficient melanocytes, which normally exhibit perinuclear melanosome aggregation because of increased retrograde melanosome transport activity, caused dispersion of melanosomes from the perinucleus to the cell periphery, but knockdown of Rab7 did not. Our findings indicated that Rab36 mediates retrograde melanosome transport in melanocytes through interaction with RILP.
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Affiliation(s)
- Takahide Matsui
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
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39
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Nottingham RM, Pusapati GV, Ganley IG, Barr FA, Lambright DG, Pfeffer SR. RUTBC2 protein, a Rab9A effector and GTPase-activating protein for Rab36. J Biol Chem 2012; 287:22740-8. [PMID: 22637480 DOI: 10.1074/jbc.m112.362558] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rab GTPases regulate vesicle budding, motility, docking, and fusion. In cells, their cycling between active, GTP-bound states and inactive, GDP-bound states is regulated by the action of opposing enzymes called guanine nucleotide exchange factors and GTPase-activating proteins (GAPs). The substrates for most RabGAPs are unknown, and the potential for cross-talk between different membrane trafficking pathways remains uncharted territory. Rab9A and its effectors regulate recycling of mannose 6-phosphate receptors from late endosomes to the trans Golgi network. We show here that RUTBC2 is a TBC domain-containing protein that binds to Rab9A specifically both in vitro and in cultured cells but is not a GAP for Rab9A. Biochemical screening of Rab protein substrates for RUTBC2 revealed highest GAP activity toward Rab34 and Rab36. In cells, membrane-associated RUTBC2 co-localizes with Rab36, and expression of wild type RUTBC2, but not the catalytically inactive, RUTBC2 R829A mutant, decreases the amount of membrane-associated Rab36 protein. These data show that RUTBC2 can act as a Rab36 GAP in cells and suggest that RUTBC2 links Rab9A function to Rab36 function in the endosomal system.
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Affiliation(s)
- Ryan M Nottingham
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
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Liu S, Storrie B. Are Rab proteins the link between Golgi organization and membrane trafficking? Cell Mol Life Sci 2012; 69:4093-106. [PMID: 22581368 DOI: 10.1007/s00018-012-1021-6] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/18/2012] [Accepted: 04/24/2012] [Indexed: 11/25/2022]
Abstract
The fundamental separation of Golgi function between subcompartments termed cisternae is conserved across all eukaryotes. Likewise, Rab proteins, small GTPases of the Ras superfamily, are putative common coordinators of Golgi organization and protein transport. However, despite sequence conservation, e.g., Rab6 and Ypt6 are conserved proteins between humans and yeast, the fundamental organization of the organelle can vary profoundly. In the yeast Saccharomyces cerevisiae, the Golgi cisternae are physically separated from one another, while in mammalian cells, the cisternae are stacked one upon the other. Moreover, in mammalian cells, many Golgi stacks are typically linked together to generate a ribbon structure. Do evolutionarily conserved Rab proteins regulate secretory membrane trafficking and diverse Golgi organization in a common manner? In mammalian cells, some Golgi-associated Rab proteins function in coordination of protein transport and maintenance of Golgi organization. These include Rab6, Rab33B, Rab1, Rab2, Rab18, and Rab43. In yeast, these include Ypt1, Ypt32, and Ypt6. Here, based on evidence from both yeast and mammalian cells, we speculate on the essential role of Rab proteins in Golgi organization and protein transport.
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Affiliation(s)
- Shijie Liu
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Seo YN, Lee YJ, Lee MY. Differential gene expression by chrysotile in human bronchial epithelial cells. Anim Cells Syst (Seoul) 2012. [DOI: 10.1080/19768354.2011.628696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
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Piccione M, Vecchio D, Cavani S, Malacarne M, Pierluigi M, Corsello G. The first case of myoclonic epilepsy in a child with a de novo 22q11.2 microduplication. Am J Med Genet A 2011; 155A:3054-9. [DOI: 10.1002/ajmg.a.34275] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 08/01/2011] [Indexed: 12/20/2022]
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Abstract
Intracellular membrane traffic defines a complex network of pathways that connects many of the membrane-bound organelles of eukaryotic cells. Although each pathway is governed by its own set of factors, they all contain Rab GTPases that serve as master regulators. In this review, we discuss how Rabs can regulate virtually all steps of membrane traffic from the formation of the transport vesicle at the donor membrane to its fusion at the target membrane. Some of the many regulatory functions performed by Rabs include interacting with diverse effector proteins that select cargo, promoting vesicle movement, and verifying the correct site of fusion. We describe cascade mechanisms that may define directionality in traffic and ensure that different Rabs do not overlap in the pathways that they regulate. Throughout this review we highlight how Rab dysfunction leads to a variety of disease states ranging from infectious diseases to cancer.
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Affiliation(s)
- Alex H Hutagalung
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA
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Rahajeng J, Giridharan SSP, Cai B, Naslavsky N, Caplan S. Important relationships between Rab and MICAL proteins in endocytic trafficking. World J Biol Chem 2010; 1:254-64. [PMID: 21537482 PMCID: PMC3083971 DOI: 10.4331/wjbc.v1.i8.254] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 07/28/2010] [Accepted: 08/04/2010] [Indexed: 02/05/2023] Open
Abstract
The internalization of essential nutrients, lipids and receptors is a crucial process for all eukaryotic cells. Accordingly, endocytosis is highly conserved across cell types and species. Once internalized, small cargo-containing vesicles fuse with early endosomes (also known as sorting endosomes), where they undergo segregation to distinct membrane regions and are sorted and transported on through the endocytic pathway. Although the mechanisms that regulate this sorting are still poorly understood, some receptors are directed to late endosomes and lysosomes for degradation, whereas other receptors are recycled back to the plasma membrane; either directly or through recycling endosomes. The Rab family of small GTP-binding proteins plays crucial roles in regulating these trafficking pathways. Rabs cycle from inactive GDP-bound cytoplasmic proteins to active GTP-bound membrane-associated proteins, as a consequence of the activity of multiple specific GTPase-activating proteins (GAPs) and GTP exchange factors (GEFs). Once bound to GTP, Rabs interact with a multitude of effector proteins that carry out Rab-specific functions. Recent studies have shown that some of these effectors are also interaction partners for the C-terminal Eps15 homology (EHD) proteins, which are also intimately involved in endocytic regulation. A particularly interesting example of common Rab-EHD interaction partners is the MICAL-like protein, MICAL-L1. MICAL-L1 and its homolog, MICAL-L2, belong to the larger MICAL family of proteins, and both have been directly implicated in regulating endocytic recycling of cell surface receptors and junctional proteins, as well as controlling cytoskeletal rearrangement and neurite outgrowth. In this review, we summarize the functional roles of MICAL and Rab proteins, and focus on the significance of their interactions and the implications for endocytic transport.
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Affiliation(s)
- Juliati Rahajeng
- Juliati Rahajeng, Sai Srinivas Panapakkam Giridharan, Bishuang Cai, Naava Naslavsky, Steve Caplan, Department of Biochemistry and Molecular Biology, and Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-5870, United States
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