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Kim B, Kim DS, Shin JG, Leem S, Cho M, Kim H, Gu KN, Seo JY, You SW, Martin AR, Park SG, Kim Y, Jeong C, Kang NG, Won HH. Mapping and annotating genomic loci to prioritize genes and implicate distinct polygenic adaptations for skin color. Nat Commun 2024; 15:4874. [PMID: 38849341 PMCID: PMC11161515 DOI: 10.1038/s41467-024-49031-4] [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: 07/04/2023] [Accepted: 05/21/2024] [Indexed: 06/09/2024] Open
Abstract
Evidence for adaptation of human skin color to regional ultraviolet radiation suggests shared and distinct genetic variants across populations. However, skin color evolution and genetics in East Asians are understudied. We quantified skin color in 48,433 East Asians using image analysis and identified associated genetic variants and potential causal genes for skin color as well as their polygenic interplay with sun exposure. This genome-wide association study (GWAS) identified 12 known and 11 previously unreported loci and SNP-based heritability was 23-24%. Potential causal genes were determined through the identification of nonsynonymous variants, colocalization with gene expression in skin tissues, and expression levels in melanocytes. Genomic loci associated with pigmentation in East Asians substantially diverged from European populations, and we detected signatures of polygenic adaptation. This large GWAS for objectively quantified skin color in an East Asian population improves understanding of the genetic architecture and polygenic adaptation of skin color and prioritizes potential causal genes.
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Affiliation(s)
- Beomsu Kim
- Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Samsung Medical Center, Seoul, 06351, Republic of Korea
| | - Dan Say Kim
- Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Samsung Medical Center, Seoul, 06351, Republic of Korea
| | - Joong-Gon Shin
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Sangseob Leem
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Minyoung Cho
- Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Samsung Medical Center, Seoul, 06351, Republic of Korea
| | - Hanji Kim
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Ki-Nam Gu
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Jung Yeon Seo
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Seung Won You
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Alicia R Martin
- Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, 02141, USA
| | - Sun Gyoo Park
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Yunkwan Kim
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea
| | - Choongwon Jeong
- School of Biological Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Nae Gyu Kang
- Research and Innovation Center, CTO, LG Household & Healthcare (LG H&H), Seoul, 07795, Republic of Korea.
| | - Hong-Hee Won
- Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Samsung Medical Center, Seoul, 06351, Republic of Korea.
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Brandt JN, Voss L, Rambo FM, Nicholson K, Thein JR, Fairchild L, Seabrook L, Lewis D, Guevara-Hernandez L, White ML, Sax L, Eichten V, Harper L, Hermann GJ. Asymmetric organelle positioning during epithelial polarization of C. elegans intestinal cells. Dev Biol 2022; 481:75-94. [PMID: 34597675 PMCID: PMC8665101 DOI: 10.1016/j.ydbio.2021.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/11/2021] [Accepted: 09/24/2021] [Indexed: 01/03/2023]
Abstract
While the epithelial cell cortex displays profound asymmetries in protein distribution and morphology along the apico-basal axis, the extent to which the cytoplasm is similarly polarized within epithelial cells remains relatively unexplored. We show that cytoplasmic organelles within C. elegans embryonic intestinal cells develop extensive apico-basal polarity at the time they establish cortical asymmetry. Nuclei and conventional endosomes, including early endosomes, late endosomes, and lysosomes, become polarized apically. Lysosome-related gut granules, yolk platelets, and lipid droplets become basally enriched. Removal of par-3 activity does not disrupt organelle positioning, indicating that cytoplasmic apico-basal asymmetry is independent of the PAR polarity pathway. Blocking the apical migration of nuclei leads to the apical positioning of gut granules and yolk platelets, whereas the asymmetric localization of conventional endosomes and lipid droplets is unaltered. This suggests that nuclear positioning organizes some, but not all, cytoplasmic asymmetries in this cell type. We show that gut granules become apically enriched when WHT-2 and WHT-7 function is disrupted, identifying a novel role for ABCG transporters in gut granule positioning during epithelial polarization. Analysis of WHT-2 and WHT-7 ATPase mutants is consistent with a WHT-2/WHT-7 heterodimer acting as a transporter in gut granule positioning. In wht-2(-) mutants, the polarized distribution of other organelles is not altered and gut granules do not take on characteristics of conventional endosomes that could have explained their apical mispositioning. During epithelial polarization wht-2(-) gut granules exhibit a loss of the Rab32/38 family member GLO-1 and ectopic expression of GLO-1 is sufficient to rescue the basal positioning of wht-2(-) and wht-7(-) gut granules. Furthermore, depletion of GLO-1 causes the mislocalization of the endolysosomal RAB-7 to gut granules and RAB-7 drives the apical mispositioning of gut granules when GLO-1, WHT-2, or WHT-7 function is disrupted. We suggest that ABC transporters residing on gut granules can regulate Rab dynamics to control organelle positioning during epithelial polarization.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Greg J. Hermann
- Corresponding author. Department of Biology, Lewis & Clark College, Portland, OR, USA, (G.J. Hermann)
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Ryniawec JM, Rogers GC. Centrosome instability: when good centrosomes go bad. Cell Mol Life Sci 2021; 78:6775-6795. [PMID: 34476544 PMCID: PMC8560572 DOI: 10.1007/s00018-021-03928-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/10/2021] [Accepted: 08/26/2021] [Indexed: 02/06/2023]
Abstract
The centrosome is a tiny cytoplasmic organelle that organizes and constructs massive molecular machines to coordinate diverse cellular processes. Due to its many roles during both interphase and mitosis, maintaining centrosome homeostasis is essential to normal health and development. Centrosome instability, divergence from normal centrosome number and structure, is a common pathognomonic cellular state tightly associated with cancers and other genetic diseases. As novel connections are investigated linking the centrosome to disease, it is critical to understand the breadth of centrosome functions to inspire discovery. In this review, we provide an introduction to normal centrosome function and highlight recent discoveries that link centrosome instability to specific disease states.
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Affiliation(s)
- John M Ryniawec
- University of Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Gregory C Rogers
- University of Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA.
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Fukuda M. Rab GTPases: Key players in melanosome biogenesis, transport, and transfer. Pigment Cell Melanoma Res 2020; 34:222-235. [PMID: 32997883 DOI: 10.1111/pcmr.12931] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
Abstract
Melanosomes are specialized intracellular organelles that produce and store melanin pigments in melanocytes, which are present in several mammalian tissues and organs, including the skin, hair, and eyes. Melanosomes form and mature stepwise (stages I-IV) in melanocytes and then are transported toward the plasma membrane along the cytoskeleton. They are subsequently transferred to neighboring keratinocytes by a largely unknown mechanism, and incorporated melanosomes are transported to the perinuclear region of the keratinocytes where they form melanin caps. Melanocytes also extend several dendrites that facilitate the efficient transfer of the melanosomes to the keratinocytes. Since the melanosome biogenesis, transport, and transfer steps require multiple membrane trafficking processes, Rab GTPases that are conserved key regulators of membrane traffic in all eukaryotes are crucial for skin and hair pigmentation. Dysfunctions of two Rab isoforms, Rab27A and Rab38, are known to cause a hypopigmentation phenotype in human type 2 Griscelli syndrome patients and in chocolate mice (related to Hermansky-Pudlak syndrome), respectively. In this review article, I review the literature on the functions of each Rab isoform and its upstream and downstream regulators in mammalian melanocytes and keratinocytes.
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Affiliation(s)
- Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan
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Combined deficiency of RAB32 and RAB38 in the mouse mimics Hermansky-Pudlak syndrome and critically impairs thrombosis. Blood Adv 2020; 3:2368-2380. [PMID: 31399401 DOI: 10.1182/bloodadvances.2019031286] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 07/01/2019] [Indexed: 12/11/2022] Open
Abstract
The biogenesis of lysosome related organelles is defective in Hermansky-Pudlak syndrome (HPS), a disorder characterized by oculocutaneous albinism and platelet dense granule (DG) defects. The first animal model of HPS was the fawn-hooded rat, harboring a spontaneous mutation inactivating the small guanosine triphosphatase Rab38 This leads to coat color dilution associated with the absence of DGs and lung morphological defects. Another RAB38 mutant, the cht mouse, has normal DGs, which has raised controversy about the role of RAB38 in DG biogenesis. We show here that murine and human, but not rat, platelets also express the closely related RAB32. To elucidate the parts played by RAB32 and RAB38 in the biogenesis of DGs in vivo and their effects on platelet functions, we generated mice inactivated for Rab32, Rab38, and both genes. Single Rab38 inactivation mimicked cht mice, whereas single Rab32 inactivation had no effect in DGs, coat color, or lung morphology. By contrast, Rab32/38 double inactivation mimicked severe HPS, with strong coat and eye pigment dilution, some enlarged lung multilamellar bodies associated with a decrease in the number of DGs. These organelles were morphologically abnormal, decreased in number, and devoid of 5-hydroxytryptamine content. In line with the storage pool defect, platelet activation was affected, resulting in severely impaired thrombus growth and prolongation of the bleeding time. Overall, our study demonstrates the absence of impact of RAB38 or RAB32 single deficiency in platelet biogenesis and function resulting from full redundancy, and characterized a new mouse model mimicking HPS devoid of DG content.
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Yang YY, Huang M, Wang Y. Targeted Proteomic Analysis of Small GTPases in Murine Adipogenesis. Anal Chem 2020; 92:6756-6763. [PMID: 32237738 DOI: 10.1021/acs.analchem.0c00974] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small GTPases are essential signaling molecules for regulating glucose uptake in adipose tissues upon insulin stimulation, and this regulation maintains an appropriate range of glycemia. The involvement of small GTPases in adipogenesis, however, has not been systemically investigated. In this study, we applied a high-throughput scheduled multiple-reaction monitoring (MRM) method, along with the use of synthetic stable isotope-labeled peptides, to identify differentially expressed small GTPase proteins during adipogenesis of cultured murine cells. We were able to quantify the relative levels of expression of 55 and 49 small GTPases accompanied by adipogenic differentiation in 3T3-L1 and C3H10T1/2 cells, respectively. When compared with analysis conducted in the data-dependent acquisition (DDA) mode, the MRM-based proteomic platform substantially increased the coverage of the small GTPase proteome. Western blot analysis further corroborated the MRM quantification results for selected small GTPases. Interestingly, overall a significant number of small GTPases were down-regulated during adipogenesis. Among them, the expression levels of Rab32 protein were consistently lower in differentiated adipocytes than the corresponding undifferentiated precursors in both cell lines. Overexpression of Rab32 in 3T3-L1 and C3H10T1/2 cells prior to adipogenesis induction suppressed their differentiation. Together, this is the first comprehensive analysis of the alterations in small GTPase proteome during adipogenesis, and we reveal a previously unrecognized role of Rab32 in adipogenic differentiation.
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Racioppi C, Coppola U, Christiaen L, Ristoratore F. Transcriptional regulation of Rab32/38, a specific marker of pigment cell formation in Ciona robusta. Dev Biol 2019; 448:111-118. [DOI: 10.1016/j.ydbio.2018.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 01/22/2023]
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Elgner F, Hildt E, Bender D. Relevance of Rab Proteins for the Life Cycle of Hepatitis C Virus. Front Cell Dev Biol 2018; 6:166. [PMID: 30564577 PMCID: PMC6288913 DOI: 10.3389/fcell.2018.00166] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/20/2018] [Indexed: 12/18/2022] Open
Abstract
Although potent direct-acting antiviral drugs for the treatment of chronic hepatitis C virus (HCV) infection are licensed, there are more than 70 million individuals suffering from chronic HCV infection. In light of the limited access to these drugs, high costs, and a lot of undiagnosed cases, it is expected that the number of HCV cases will not decrease worldwide in the next years. Therefore, and due to the paradigmatic character of HCV for deciphering the crosstalk between viral pathogens and the host cell, characterization of HCV life cycle remains a challenge. HCV belongs to the family of Flaviviridae. As an enveloped virus HCV life cycle depends in many steps on intracellular trafficking. Rab GTPases, a large family of small GTPases, play a central role in intracellular trafficking processes controlling fusion, uncoating, vesicle budding, motility by recruiting specific effector proteins. This review describes the relevance of various Rab proteins for the different steps of the HCV life cycle.
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Affiliation(s)
- Fabian Elgner
- Department of Virology, Paul-Ehrlich-Institut, Langen, Germany
| | - Eberhard Hildt
- Department of Virology, Paul-Ehrlich-Institut, Langen, Germany
| | - Daniela Bender
- Department of Virology, Paul-Ehrlich-Institut, Langen, Germany
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Myosin Va's adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro. Proc Natl Acad Sci U S A 2017; 114:E4714-E4723. [PMID: 28559319 DOI: 10.1073/pnas.1619473114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pigment organelles, or melanosomes, are transported by kinesin, dynein, and myosin motors. As such, melanosome transport is an excellent model system to study the functional relationship between the microtubule- and actin-based transport systems. In mammalian melanocytes, it is well known that the Rab27a/melanophilin/myosin Va complex mediates actin-based transport in vivo. However, pathways that regulate the overall directionality of melanosomes on the actin/microtubule networks have not yet been delineated. Here, we investigated the role of PKA-dependent phosphorylation on the activity of the actin-based Rab27a/melanophilin/myosin Va transport complex in vitro. We found that melanophilin, specifically its C-terminal actin-binding domain (ABD), is a target of PKA. Notably, in vitro phosphorylation of the ABD closely recapitulated the previously described in vivo phosphorylation pattern. Unexpectedly, we found that phosphorylation of the ABD affected neither the interaction of the complex with actin nor its movement along actin tracks. Surprisingly, the phosphorylation state of melanophilin was instead important for reversible association with microtubules in vitro. Dephosphorylated melanophilin preferred binding to microtubules even in the presence of actin, whereas phosphorylated melanophilin associated with actin. Indeed, when actin and microtubules were present simultaneously, melanophilin's phosphorylation state enforced track selection of the Rab27a/melanophilin/myosin Va transport complex. Collectively, our results unmasked the regulatory dominance of the melanophilin adaptor protein over its associated motor and offer an unexpected mechanism by which filaments of the cytoskeletal network compete for the moving organelles to accomplish directional transport on the cytoskeleton in vivo.
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Ohbayashi N, Fukuda M, Kanaho Y. Rab32 subfamily small GTPases: pleiotropic Rabs in endosomal trafficking. J Biochem 2017; 162:65-71. [DOI: 10.1093/jb/mvx027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 03/21/2017] [Indexed: 11/13/2022] Open
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Hepatitis C Virus-Induced Rab32 Aggregation and Its Implications for Virion Assembly. J Virol 2017; 91:JVI.01662-16. [PMID: 27852857 DOI: 10.1128/jvi.01662-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 11/09/2016] [Indexed: 01/09/2023] Open
Abstract
Hepatitis C virus (HCV) is highly dependent on cellular factors for viral propagation. Using high-throughput next-generation sequencing, we analyzed the host transcriptomic changes and identified 30 candidate genes which were upregulated in cell culture-grown HCV (HCVcc)-infected cells. Of these candidates, we selected Rab32 for further investigation. Rab32 is a small GTPase that regulates a variety of intracellular membrane-trafficking events in various cell types. In this study, we demonstrated that both mRNA and protein levels of Rab32 were increased in HCV-infected cells. Furthermore, we showed that HCV infection converted the predominantly expressed GTP-bound Rab32 to GDP-bound Rab32, contributing to the aggregation of Rab32 and thus making it less sensitive to cellular degradation machinery. In addition, GDP-bound Rab32 selectively interacted with HCV core protein and deposited core protein into the endoplasmic reticulum (ER)-associated Rab32-derived aggregated structures in the perinuclear region, which were likely to be viral assembly sites. Using RNA interference technology, we demonstrated that Rab32 was required for the assembly step but not for other stages of the HCV life cycle. Taken together, these data suggest that HCV may modulate Rab32 activity to facilitate virion assembly. IMPORTANCE Rab32, a member of the Ras superfamily of small GTPases, regulates various intracellular membrane-trafficking events in many cell types. In this study, we showed that HCV infection concomitantly increased Rab32 expression at the transcriptional level and altered the balance between GDP- and GTP-bound Rab32 toward production of Rab32-GDP. GDP-bound Rab32 selectively interacted with HCV core protein and enriched core in the ER-associated Rab32-derived aggregated structures that were probably necessary for viral assembly. Indeed, we showed that Rab32 was specifically required for the assembly of HCV. Collectively, our study identifies that Rab32 is a novel host factor essential for HCV particle assembly.
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Abstract
Our immune system is engaged in a continuous battle against invading pathogens, many of which have evolved to survive in intracellular niches of mammalian hosts. A variety of cellular processes are involved in preventing bacterial invasion or in killing bacteria that successfully invade host cells. Recently, the Rab GTPase Rab32 emerged as critical regulator of a host defense pathway that can eliminate bacterial pathogens. Salmonella enterica is an intracellular bacterium and a major cause of infections and deaths in humans. Rab32 and its guanine nucleotide exchange factor BLOC-3 are essential to prevent the growth of the human-restricted Salmonella enterica serovar Typhi (S. Typhi) in mice, a non-susceptible host. The importance of the Rab32/BLOC-3 pathway has been recently confirmed by the finding that broad-host Salmonella enterica serovars deliver 2 bacterial effectors to neutralize this pathway and infect mice. Rab32 has also been shown to control infection by Listeria monocytogenes, another medically relevant intracellular pathogen. In addition, genetic evidence indicate a possible role of Rab32 in controlling leprosy, a disease caused by Mycobacterium leprae in humans, suggesting that a Rab32-dependent pathway can also act as a host defense pathway in humans. The Rab32 role in bacterial pathogen restriction is discussed here and compared to the function of this GTPase in other cellular processes.
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Affiliation(s)
- Virtu Solano-Collado
- a Institute of Medical Sciences, University of Aberdeen , Foresterhill , Aberdeen , UK
| | - Adam Rofe
- a Institute of Medical Sciences, University of Aberdeen , Foresterhill , Aberdeen , UK
| | - Stefania Spanò
- a Institute of Medical Sciences, University of Aberdeen , Foresterhill , Aberdeen , UK
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Li C, Yu SSB. Rab proteins as regulators of lipid droplet formation and lipolysis. Cell Biol Int 2016; 40:1026-32. [PMID: 27453349 DOI: 10.1002/cbin.10650] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 07/22/2016] [Indexed: 12/11/2022]
Abstract
Lipid droplets (LDs) are highly dynamic organelles that not only store neutral lipids but also are involved in multiple cellular processes. Dysregulation of lipogenesis or lipolysis greatly contributes to the pathogenesis of several human diseases, including obesity, diabetes, and fatty liver disease. Rab proteins have been found to be associated with LDs in proteomic studies and are also known to extensively regulate intracellular membrane traffic, suggesting that LDs actively communicate with other membrane compartments to maintain energy homeostasis. This review discusses recent studies that provide mechanistic insights into the regulation of LD formation and catabolism by Rab proteins in mammalian cells.
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Affiliation(s)
- Chunman Li
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Sidney S B Yu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China. .,Epithelial Cell Biology Research Centre, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
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Tang BL. Rab32/38 and the xenophagic restriction of intracellular bacteria replication. Microbes Infect 2016; 18:595-603. [PMID: 27256464 DOI: 10.1016/j.micinf.2016.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/20/2016] [Accepted: 05/20/2016] [Indexed: 12/18/2022]
Abstract
Rab GTPases' subversion by intracellular pathogens during infection has been extensively documented. Recent findings have implicated a key intracellular bacterial restriction/containment function for Rab32/38 in Salmonella species in macrophages and Listeria monocytogenes in dendritic cells. Rab32/38 aids the phagolysosome maturation, and mediates a parallel xenophagy mechanism by engaging prohibitins.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry and NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
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15
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Rab32 and Rab38 genes in chordate pigmentation: an evolutionary perspective. BMC Evol Biol 2016; 16:26. [PMID: 26818140 PMCID: PMC4728774 DOI: 10.1186/s12862-016-0596-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 01/18/2016] [Indexed: 11/25/2022] Open
Abstract
Background The regulation of cellular membrane trafficking in all eukaryotes is a very complex mechanism, mostly regulated by the Rab family proteins. Among all membrane-enclosed organelles, melanosomes are the cellular site for synthesis, storage and transport of melanin granules, making them an excellent model for studies on organelle biogenesis and motility. Specific Rab proteins, as Rab32 and Rab38, have been shown to play a key role in melanosome biogenesis. We analysed the Rab32 and Rab38 genes in the teleost zebrafish and in the cephalochordate amphioxus, gaining insight on their evolutionary history following gene and genome duplications. Results We studied the molecular evolution of Rab supergroup III in deuterostomes by phylogenetic reconstruction, intron and synteny conservation. We discovered a novel amino acid stretch, named FALK, shared by three related classes belonging to Rab supergroup III: Rab7L1, Rab32LO and Rab32/Rab38. Among these, we demonstrated that the Rab32LO class, already present in the last common eukaryotic ancestor, was lost in urochordates and vertebrates. Synteny shows that one zebrafish gene, Rab38a, which is expressed in pigmented cells, retained the linkage with tyrosinase, a protein essential for pigmentation. Moreover, the chromosomal linkage of Rab32 or Rab38 with a member of the glutamate receptor metabotropic (Grm) family has been retained in all analysed gnathostomes, suggesting a conserved microsynteny in the vertebrate ancestor. Expression patterns of Rab32 and Rab38 genes in zebrafish, and Rab32/38 in amphioxus, indicate their involvement in development of pigmented cells and notochord. Conclusions Phylogenetic, intron conservation and synteny analyses point towards an evolutionary scenario based on a duplication of a single invertebrate Rab32/38 gene giving rise to vertebrate Rab32 and Rab38. The expression patterns of Rab38 paralogues highlight sub-functionalization event. Finally, the discovery of a chromosomal linkage between the Rab32 or Rab38 gene with a Grm opens new perspectives on possible conserved bystander gene regulation across the vertebrate evolution. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0596-1) contains supplementary material, which is available to authorized users.
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Pei Y, Yue L, Zhang W, Wang Y, Wen B, Zhong L, Xiang J, Li J, Zhang S, Wang H, Mu H, Wei Q, Han J. Improvement in Mouse iPSC Induction by Rab32 Reveals the Importance of Lipid Metabolism during Reprogramming. Sci Rep 2015; 5:16539. [PMID: 26559473 PMCID: PMC4642270 DOI: 10.1038/srep16539] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 10/15/2015] [Indexed: 11/30/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) have variable expression levels of a series of genes that affect their pluripotent potential, but the regulatory mechanisms controlling reprogramming remain unclear. By testing the efficiency of iPSC generation using Oct4, Sox2, Klf4 (termed OSK) plus one additional gene, we found that Rab32 improved reprogramming efficiency. We established a system for detecting the number and the size of lipid droplets and autophagosomes per cell for tracking their morphological changes during reprogramming. Our results showed that Rab32 increased lipid storage during the early and middle stages, and also increased autophagy during the middle stage of reprogramming. These findings were further confirmed by the up-regulation of lipid biosynthesis and autophagosome formation related genes, of which their expression could improve iPSC induction. The inhibition of lipid biosynthesis and autophagosome formation significantly reduced reprogramming efficiency, and the inhibition of lipid synthesis phenotype could be rescued by the overexpression of Rab32. In addition, the expression of pluripotency genes such as Klf2, Nr5a2 and Tbx3, was up-regulated by Rab32. These results demonstrated that Rab32 could improve the induction of iPSCs through the enhancement of lipid biosynthesis, highlighting the importance of lipid metabolism during reprogramming.
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Affiliation(s)
- Yangli Pei
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Liang Yue
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Wei Zhang
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yanliang Wang
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Bingqiang Wen
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Liang Zhong
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Jinzhu Xiang
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Junhong Li
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Shaopeng Zhang
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Hanning Wang
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Haiyuan Mu
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Qingqing Wei
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Jianyong Han
- State Key Laboratories for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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17
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Niyogi S, Jimenez V, Girard-Dias W, de Souza W, Miranda K, Docampo R. Rab32 is essential for maintaining functional acidocalcisomes, and for growth and infectivity of Trypanosoma cruzi. J Cell Sci 2015; 128:2363-73. [PMID: 25964650 DOI: 10.1242/jcs.169466] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/30/2015] [Indexed: 02/01/2023] Open
Abstract
The contractile vacuole complex (CVC) of Trypanosoma cruzi, the etiologic agent of Chagas disease, collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress; it also has a role in cell shrinking after hyperosmotic stress. Here, we report that, in addition to its role in osmoregulation, the CVC of T. cruzi has a role in the biogenesis of acidocalcisomes. Expression of dominant-negative mutants of the CVC-located small GTPase Rab32 (TcCLB.506289.80) results in lower numbers of less-electron-dense acidocalcisomes, lower content of polyphosphate, lower capacity for acidocalcisome acidification and Ca(2+) uptake that is driven by the vacuolar proton pyrophosphatase and the Ca(2+)-ATPase, respectively, as well as less-infective parasites, revealing the role of this organelle in parasite infectivity. By using fluorescence, electron microscopy and electron tomography analyses, we provide further evidence of the active contact of acidocalcisomes with the CVC, indicating an active exchange of proteins between the two organelles.
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Affiliation(s)
- Sayantanee Niyogi
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Veronica Jimenez
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Wendell Girard-Dias
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens - Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Wanderley de Souza
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens - Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Diretoria de Metrologia Aplicada a Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Xerém, Rio de Janeiro 25250-020, Brazil
| | - Kildare Miranda
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens - Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Diretoria de Metrologia Aplicada a Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Xerém, Rio de Janeiro 25250-020, Brazil
| | - Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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18
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Waschbüsch D, Michels H, Strassheim S, Ossendorf E, Kessler D, Gloeckner CJ, Barnekow A. LRRK2 transport is regulated by its novel interacting partner Rab32. PLoS One 2014; 9:e111632. [PMID: 25360523 PMCID: PMC4216093 DOI: 10.1371/journal.pone.0111632] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 09/29/2014] [Indexed: 11/18/2022] Open
Abstract
Leucine-rich repeat kinase 2 (LRRK2) is a multi-domain 280 kDa protein that is linked to Parkinson's disease (PD). Mutations especially in the GTPase and kinase domains of LRRK2 are the most common causes of heritable PD and are also found in sporadic forms of PD. Although the cellular function of LRRK2 is largely unknown there is increasing evidence that these mutations cause cell death due to autophagic dysfunction and mitochondrial damage. Here, we demonstrate a novel mechanism of LRRK2 binding and transport, which involves the small GTPases Rab32 and Rab38. Rab32 and its closest homologue Rab38 are known to organize the trans-Golgi network and transport of key enzymes in melanogenesis, whereas their function in non-melanogenic cells is still not well understood. Cellular processes such as autophagy, mitochondrial dynamics, phagocytosis or inflammatory processes in the brain have previously been linked to Rab32. Here, we demonstrate that Rab32 and Rab38, but no other GTPase tested, directly interact with LRRK2. GFP-Trap analyses confirmed the interaction of Rab32 with the endogenous LRRK2. In yeast two-hybrid experiments we identified a predicted coiled-coil motif containing region within the aminoterminus of LRRK2 as the possible interacting domain. Fluorescence microscopy demonstrated a co-localization of Rab32 and LRRK2 at recycling endosomes and transport vesicles, while overexpression of a constitutively active mutant of Rab32 led to an increased co-localization with Rab7/9 positive perinuclear late endosomes/MVBs. Subcellular fractionation experiments supported the novel role of Rab32 in LRRK2 late endosomal transport and sorting in the cell. Thus, Rab32 may regulate the physiological functions of LRRK2.
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Affiliation(s)
- Dieter Waschbüsch
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
- * E-mail:
| | - Helen Michels
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
| | - Swantje Strassheim
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
| | - Edith Ossendorf
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
| | - Daniel Kessler
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
| | - Christian Johannes Gloeckner
- Research Unit Protein Science, Helmholtz Zentrum München, Neuherberg, Germany
- Medical Proteome Center, Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Angelika Barnekow
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
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19
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Daniele T, Schiaffino MV. Organelle biogenesis and interorganellar connections: Better in contact than in isolation. Commun Integr Biol 2014; 7:e29587. [PMID: 25346798 PMCID: PMC4203768 DOI: 10.4161/cib.29587] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 06/15/2014] [Indexed: 12/22/2022] Open
Abstract
Membrane contact sites (MCSs) allow the exchange of molecules and information between organelles, even when their membranes cannot fuse directly. In recent years, a number of functions have been attributed to these contacts, highlighting their critical role in cell homeostasis. Although inter-organellar connections typically involve the endoplasmic reticulum (ER), we recently reported the presence of a novel MCSs between melanosomes and mitochondria. Melanosome-mitochondrion contacts appear mediated by fibrillar bridges resembling the protein tethers linking mitochondria and the ER, both for their ultrastructural features and the involvement of Mitofusin 2. The frequency of these connections correlates spatially and timely with melanosome biogenesis, suggesting a functional link between the 2 processes and in general that organelle biogenesis in the secretory pathway requires interorganellar crosstalks at multiple steps. Here, we summarize the different functions attributed to MCSs, and discuss their possible relevance for the newly identified melanosome-mitochondrion liaison.
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Affiliation(s)
- Tiziana Daniele
- San Raffaele Scientific Institute; Experimental Imaging Center; Milan, Italy ; University of Genoa; Department of Experimental Medicine; Genoa, Italy
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20
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Hesketh GG, Pérez-Dorado I, Jackson LP, Wartosch L, Schäfer IB, Gray SR, McCoy AJ, Zeldin OB, Garman EF, Harbour ME, Evans PR, Seaman MNJ, Luzio JP, Owen DJ. VARP is recruited on to endosomes by direct interaction with retromer, where together they function in export to the cell surface. Dev Cell 2014; 29:591-606. [PMID: 24856514 PMCID: PMC4059916 DOI: 10.1016/j.devcel.2014.04.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 02/03/2014] [Accepted: 04/09/2014] [Indexed: 11/18/2022]
Abstract
VARP is a Rab32/38 effector that also binds to the endosomal/lysosomal R-SNARE VAMP7. VARP binding regulates VAMP7 participation in SNARE complex formation and can therefore influence VAMP7-mediated membrane fusion events. Mutant versions of VARP that cannot bind Rab32:GTP, designed on the basis of the VARP ankyrin repeat/Rab32:GTP complex structure described here, unexpectedly retain endosomal localization, showing that VARP recruitment is not dependent on Rab32 binding. We show that recruitment of VARP to the endosomal membrane is mediated by its direct interaction with VPS29, a subunit of the retromer complex, which is involved in trafficking from endosomes to the TGN and the cell surface. Transport of GLUT1 from endosomes to the cell surface requires VARP, VPS29, and VAMP7 and depends on the direct interaction between VPS29 and VARP. Finally, we propose that endocytic cycling of VAMP7 depends on its interaction with VARP and, consequently, also on retromer.
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Affiliation(s)
- Geoffrey G Hesketh
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Inmaculada Pérez-Dorado
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Lauren P Jackson
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Lena Wartosch
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Ingmar B Schäfer
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Sally R Gray
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Airlie J McCoy
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Oliver B Zeldin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Elspeth F Garman
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Michael E Harbour
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Philip R Evans
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Matthew N J Seaman
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
| | - J Paul Luzio
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
| | - David J Owen
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
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21
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Scholey JM. Kinesin-2: a family of heterotrimeric and homodimeric motors with diverse intracellular transport functions. Annu Rev Cell Dev Biol 2013; 29:443-69. [PMID: 23750925 DOI: 10.1146/annurev-cellbio-101512-122335] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Kinesin-2 was first purified as a heterotrimeric, anterograde, microtubule-based motor consisting of two distinct kinesin-related subunits and a novel associated protein (KAP) that is currently best known for its role in intraflagellar transport and ciliogenesis. Subsequent work, however, has revealed diversity in the oligomeric state of different kinesin-2 motors owing to the combinatorial heterodimerization of its subunits and the coexistence of both heterotrimeric and homodimeric kinesin-2 motors in some cells. Although the functional significance of the homo- versus heteromeric organization of kinesin-2 motor subunits and the role of KAP remain uncertain, functional studies suggest that cooperation between different types of kinesin-2 motors or between kinesin-2 and a member of a different motor family can generate diverse patterns of anterograde intracellular transport. Moreover, despite being restricted to ciliated eukaryotes, kinesin-2 motors are now known to drive diverse transport events outside cilia. Here, I review the organization, assembly, phylogeny, biological functions, and motility mechanism of this diverse family of intracellular transport motors.
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Affiliation(s)
- Jonathan M Scholey
- Department of Molecular and Cell Biology, University of California, Davis, California 95616;
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22
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Ellis K, Bagwell J, Bagnat M. Notochord vacuoles are lysosome-related organelles that function in axis and spine morphogenesis. ACTA ACUST UNITED AC 2013; 200:667-79. [PMID: 23460678 PMCID: PMC3587825 DOI: 10.1083/jcb.201212095] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The zebrafish notochord vacuole, which has long been known to be important for vertebrate development but poorly classified at a cell biological level, is identified as a specialized lysosome-related organelle that is necessary both early, for embryonic axis elongation, and late, for spine morphogenesis. The notochord plays critical structural and signaling roles during vertebrate development. At the center of the vertebrate notochord is a large fluid-filled organelle, the notochord vacuole. Although these highly conserved intracellular structures have been described for decades, little is known about the molecular mechanisms involved in their biogenesis and maintenance. Here we show that zebrafish notochord vacuoles are specialized lysosome-related organelles whose formation and maintenance requires late endosomal trafficking regulated by the vacuole-specific Rab32a and H+-ATPase–dependent acidification. We establish that notochord vacuoles are required for body axis elongation during embryonic development and identify a novel role in spine morphogenesis. Thus, the vertebrate notochord plays important structural roles beyond early development.
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Affiliation(s)
- Kathryn Ellis
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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23
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Nottingham RM, Ganley IG, Barr FA, Lambright DG, Pfeffer SR. RUTBC1 protein, a Rab9A effector that activates GTP hydrolysis by Rab32 and Rab33B proteins. J Biol Chem 2011; 286:33213-22. [PMID: 21808068 DOI: 10.1074/jbc.m111.261115] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rab GTPases regulate all steps of membrane trafficking. Their interconversion between active, GTP-bound states and inactive, GDP-bound states is regulated by guanine nucleotide exchange factors and GTPase-activating proteins. The substrates for most Rab GTPase-activating proteins (GAPs) are unknown. Rab9A and its effectors regulate transport of mannose 6-phosphate receptors from late endosomes to the trans-Golgi network. We show here that RUTBC1 is a Tre2/Bub2/Cdc16 domain-containing protein that binds to Rab9A-GTP both in vitro and in cultured cells, but is not a GTPase-activating protein for Rab9A. Biochemical screening of RUTBC1 Rab protein substrates revealed highest in vitro GTP hydrolysis-activating activity with Rab32 and Rab33B. Catalysis required Arg-803 of RUTBC1, and RUTBC1 could activate a catalytically inhibited Rab33B mutant (Q92A), in support of a dual finger mechanism for RUTBC1 action. Rab9A binding did not influence GAP activity of bead-bound RUTBC1 protein. In cells and cell extracts, RUTBC1 influenced the ability of Rab32 to bind its effector protein, Varp, consistent with a physiological role for RUTBC1 in regulating Rab32. In contrast, binding of Rab33B to its effector protein, Atg16L1, was not influenced by RUTBC1 in cells or extracts. The identification of a protein that binds Rab9A and inactivates Rab32 supports a model in which Rab9A and Rab32 act in adjacent pathways at the boundary between late endosomes and the biogenesis of lysosome-related organelles.
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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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24
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Ulrich PN, Jimenez V, Park M, Martins VP, Atwood J, Moles K, Collins D, Rohloff P, Tarleton R, Moreno SNJ, Orlando R, Docampo R. Identification of contractile vacuole proteins in Trypanosoma cruzi. PLoS One 2011; 6:e18013. [PMID: 21437209 PMCID: PMC3060929 DOI: 10.1371/journal.pone.0018013] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 02/22/2011] [Indexed: 11/19/2022] Open
Abstract
Contractile vacuole complexes are critical components of cell volume regulation
and have been shown to have other functional roles in several free-living
protists. However, very little is known about the functions of the contractile
vacuole complex of the parasite Trypanosoma cruzi, the
etiologic agent of Chagas disease, other than a role in osmoregulation.
Identification of the protein composition of these organelles is important for
understanding their physiological roles. We applied a combined proteomic and
bioinfomatic approach to identify proteins localized to the contractile vacuole.
Proteomic analysis of a T. cruzi fraction enriched for
contractile vacuoles and analyzed by one-dimensional gel electrophoresis and
LC-MS/MS resulted in the addition of 109 newly detected proteins to the group of
expressed proteins of epimastigotes. We also identified different peptides that
map to at least 39 members of the dispersed gene family 1 (DGF-1) providing
evidence that many members of this family are simultaneously expressed in
epimastigotes. Of the proteins present in the fraction we selected several
homologues with known localizations in contractile vacuoles of other organisms
and others that we expected to be present in these vacuoles on the basis of
their potential roles. We determined the localization of each by expression as
GFP-fusion proteins or with specific antibodies. Six of these putative proteins
(Rab11, Rab32, AP180, ATPase subunit B, VAMP1, and phosphate transporter)
predominantly localized to the vacuole bladder. TcSNARE2.1, TcSNARE2.2, and
calmodulin localized to the spongiome. Calmodulin was also cytosolic. Our
results demonstrate the utility of combining subcellular fractionation,
proteomic analysis, and bioinformatic approaches for localization of organellar
proteins that are difficult to detect with whole cell methodologies. The CV
localization of the proteins investigated revealed potential novel roles of
these organelles in phosphate metabolism and provided information on the
potential participation of adaptor protein complexes in their biogenesis.
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Affiliation(s)
- Paul N. Ulrich
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Veronica Jimenez
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Miyoung Park
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Vicente P. Martins
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - James Atwood
- Complex Carbohydrate Research Center,
University of Georgia, Athens, Georgia, United States of America
| | - Kristen Moles
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Dalis Collins
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Peter Rohloff
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Rick Tarleton
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Ron Orlando
- Complex Carbohydrate Research Center,
University of Georgia, Athens, Georgia, United States of America
| | - Roberto Docampo
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
- * E-mail:
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25
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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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26
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Tamura K, Ohbayashi N, Ishibashi K, Fukuda M. Structure-function analysis of VPS9-ankyrin-repeat protein (Varp) in the trafficking of tyrosinase-related protein 1 in melanocytes. J Biol Chem 2010; 286:7507-21. [PMID: 21187289 DOI: 10.1074/jbc.m110.191205] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Because Varp (VPS9-ankyrin-repeat protein)/Ankrd27 specifically binds two small GTPases, Rab32 and Rab38, which redundantly regulate the trafficking of melanogenic enzymes in mammalian epidermal melanocytes, it has recently been implicated in the regulation of trafficking of a melanogenic enzyme tyrosinase-related protein 1 (Tyrp1) to melanosomes. However, the functional interaction between Rab32/38 and Varp and the involvement of the VPS9 domain (i.e. Rab21-GEF domain) in Tyrp1 trafficking have never been elucidated. In this study, we succeeded in identifying critical residues of Rab32/38 and Varp that are critical for the formation of the Rab32/38·Varp complex by performing Ala-based site-directed mutagenesis, and we discovered that a conserved Val residue in the switch II region of Rab32(Val-92) and Rab38(Val-78) is required for Varp binding activity and that its point mutant, Rab38(V78A), does not support Tyrp1 trafficking in Rab32/38-deficient melanocytes. We also identified two critical residues for Rab32/38 binding in the Varp ANKR1 domain and demonstrated that their point mutants, Varp(Q509A) and Varp(Y550A), do not support peripheral melanosomal distribution of Tyrp1 in Varp-deficient cells. Interestingly, the VPS9 domain point mutants, Varp(D310A) and Varp(Y350A), did support Tyrp1 trafficking in Varp-deficient cells, and knockdown of Rab21 had no effect on Tyrp1 distribution. We also found evidence for the functional interaction between a vesicle SNARE VAMP7/TI-VAMP and Varp in Tyrp1 trafficking. These results collectively indicated that both the Rab32/38 binding activity and VAMP7 binding activity of Varp are essential for trafficking of Tyrp1 in melanocytes but that activation of Rab21 by the VPS9 domain is not necessary for Tyrp1 trafficking.
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Affiliation(s)
- Kanako Tamura
- 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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27
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Bui M, Gilady SY, Fitzsimmons REB, Benson MD, Lynes EM, Gesson K, Alto NM, Strack S, Scott JD, Simmen T. Rab32 modulates apoptosis onset and mitochondria-associated membrane (MAM) properties. J Biol Chem 2010; 285:31590-602. [PMID: 20670942 DOI: 10.1074/jbc.m110.101584] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitochondria-associated membrane (MAM) has emerged as an endoplasmic reticulum (ER) signaling hub that accommodates ER chaperones, including the lectin calnexin. At the MAM, these chaperones control ER homeostasis but also play a role in the onset of ER stress-mediated apoptosis, likely through the modulation of ER calcium signaling. These opposing roles of MAM-localized chaperones suggest the existence of mechanisms that regulate the composition and the properties of ER membrane domains. Our results now show that the GTPase Rab32 localizes to the ER and mitochondria, and we identify this protein as a regulator of MAM properties. Consistent with such a role, Rab32 modulates ER calcium handling and disrupts the specific enrichment of calnexin on the MAM, while not affecting the ER distribution of protein-disulfide isomerase and mitofusin-2. Furthermore, Rab32 determines the targeting of PKA to mitochondrial and ER membranes and through its overexpression or inactivation increases the phosphorylation of Bad and of Drp1. Through a combination of its functions as a PKA-anchoring protein and a regulator of MAM properties, the activity and expression level of Rab32 determine the speed of apoptosis onset.
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Affiliation(s)
- Michael Bui
- Department of Cell Biology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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28
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Schiaffino MV. Signaling pathways in melanosome biogenesis and pathology. Int J Biochem Cell Biol 2010; 42:1094-104. [PMID: 20381640 DOI: 10.1016/j.biocel.2010.03.023] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 03/28/2010] [Accepted: 03/30/2010] [Indexed: 12/24/2022]
Abstract
Melanosomes are the specialized intracellular organelles of pigment cells devoted to the synthesis, storage and transport of melanin pigments, which are responsible for most visible pigmentation in mammals and other vertebrates. As a direct consequence, any genetic mutation resulting in alteration of melanosomal function, either because affecting pigment cell survival, migration and differentiation, or because interfering with melanosome biogenesis, transport and transfer to keratinocytes, is immediately translated into color variations of skin, fur, hair or eyes. Thus, over 100 genes and proteins have been identified as pigmentary determinants in mammals, providing us with a deep understanding of this biological system, which functions by using mechanisms and processes that have parallels in other tissues and organs. In particular, many genes implicated in melanosome biogenesis have been characterized, so that melanosomes represent an incredible source of information and a model for organelles belonging to the secretory pathway. Furthermore, the function of melanosomes can be associated with common physiological phenotypes, such as variation of pigmentation among individuals, and with rare pathological conditions, such as albinism, characterized by severe visual defects. Among the most relevant mechanisms operating in melanosome biogenesis are the signal transduction pathways mediated by two peculiar G protein-coupled receptors: the melanocortin-1 receptor (MC1R), involved in the fair skin/red hair phenotype and skin cancer; and OA1 (GPR143), whose loss-of-function results in X-linked ocular albinism. This review will focus on the most recent novelties regarding the functioning of these two receptors, by highlighting emerging signaling mechanisms and general implications for cell biology and pathology.
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Mechanisms of protein kinase A anchoring. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:235-330. [PMID: 20801421 DOI: 10.1016/s1937-6448(10)83005-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The second messenger cyclic adenosine monophosphate (cAMP), which is produced by adenylyl cyclases following stimulation of G-protein-coupled receptors, exerts its effect mainly through the cAMP-dependent serine/threonine protein kinase A (PKA). Due to the ubiquitous nature of the cAMP/PKA system, PKA signaling pathways underlie strict spatial and temporal control to achieve specificity. A-kinase anchoring proteins (AKAPs) bind to the regulatory subunit dimer of the tetrameric PKA holoenzyme and thereby target PKA to defined cellular compartments in the vicinity of its substrates. AKAPs promote the termination of cAMP signals by recruiting phosphodiesterases and protein phosphatases, and the integration of signaling pathways by binding additional signaling proteins. AKAPs are a heterogeneous family of proteins that only display similarity within their PKA-binding domains, amphipathic helixes docking into a hydrophobic groove formed by the PKA regulatory subunit dimer. This review summarizes the current state of information on compartmentalized cAMP/PKA signaling with a major focus on structural aspects, evolution, diversity, and (patho)physiological functions of AKAPs and intends to outline newly emerging directions of the field, such as the elucidation of AKAP mutations and alterations of AKAP expression in human diseases, and the validation of AKAP-dependent protein-protein interactions as new drug targets. In addition, alternative PKA anchoring mechanisms employed by noncanonical AKAPs and PKA catalytic subunit-interacting proteins are illustrated.
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Hirota Y, Tanaka Y. A small GTPase, human Rab32, is required for the formation of autophagic vacuoles under basal conditions. Cell Mol Life Sci 2009; 66:2913-32. [PMID: 19593531 PMCID: PMC11115675 DOI: 10.1007/s00018-009-0080-9] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 06/16/2009] [Accepted: 06/18/2009] [Indexed: 12/26/2022]
Abstract
Here we show that a small GTPase, Rab32, is a novel protein required for the formation of autophagic vacuoles. We found that the wild-type or GTP-bound form of human Rab32 expressed in HeLa and COS cells is predominantly localized to the endoplasmic reticulum (ER), and overexpression induces the formation of autophagic vacuoles containing an autophagosome marker protein LC3, the ER-resident protein calnexin and endosomal/lysosomal membrane protein LAMP-2, even under nutrient-rich conditions. The recruitment of Rab32 to the ER membrane was necessary for autophagic vacuole formation, suggesting involvement of the ER as a source of autophagosome membranes. In contrast, the expression of the inactive form of, or siRNA-specific for, Rab32 caused the formation of p62/SQSTM1 and ubiquitinated protein-accumulating aggresome-like structures and significantly prevented constitutive autophagy. We postulate that Rab32 facilitates the formation of autophagic vacuoles whose membranes are derived from the ER and regulates the clearance of aggregated proteins by autophagy.
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Affiliation(s)
- Yuko Hirota
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Fukuoka, 812-8582 Japan
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Fukuoka, 812-8582 Japan
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Carnegie GK, Means CK, Scott JD. A-kinase anchoring proteins: from protein complexes to physiology and disease. IUBMB Life 2009; 61:394-406. [PMID: 19319965 DOI: 10.1002/iub.168] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Protein scaffold complexes are a key mechanism by which a common signaling pathway can serve many different functions. Sequestering a signaling enzyme to a specific subcellular environment not only ensures that the enzyme is near its relevant targets, but also segregates this activity to prevent indiscriminate phosphorylation of other substrates. One family of diverse, well-studied scaffolding proteins are the A-kinase anchoring proteins (AKAPs). These anchoring proteins form multi-protein complexes that integrate cAMP signaling with other pathways and signaling events. In this review, we focus on recent advances in the elucidation of AKAP function.
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Affiliation(s)
- Graeme K Carnegie
- Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, School of Medicine, Seattle, Washington 98195, USA.
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Tamura K, Ohbayashi N, Maruta Y, Kanno E, Itoh T, Fukuda M. Varp is a novel Rab32/38-binding protein that regulates Tyrp1 trafficking in melanocytes. Mol Biol Cell 2009; 20:2900-8. [PMID: 19403694 DOI: 10.1091/mbc.e08-12-1161] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Two small GTPase Rabs, Rab32 and Rab38, have recently been proposed to regulate trafficking of melanogenic enzymes to melanosomes in mammalian epidermal melanocytes; however, the exact molecular mechanism of Rab32/38-mediated transport of melanogenic enzymes has never been clarified, because no Rab32/38-specific effector has ever been identified. In this study, we screened for a Rab32/38-specific effector by a yeast two-hybrid assay using a guanosine triphosphate (GTP)-locked Rab32/38 as bait and found that VPS9-ankyrin-repeat protein (Varp)/Ankrd27, characterized previously as a guanine nucleotide exchange factor (GEF) for Rab21, functions as a specific Rab32/38-binding protein in mouse melanocyte cell line melan-a. Deletion analysis showed that the first ankyrin-repeat (ANKR1) domain functions as a GTP-dependent Rab32/38-binding domain, but that the N-terminal VPS9 domain (i.e., Rab21-GEF domain) does not. Small interfering RNA-mediated knockdown of endogenous Varp in melan-a cells caused a dramatic reduction in Tyrp1 (tyrosinase-related protein 1) signals from melanosomes but did not cause any reduction in Pmel17 signals. Furthermore, expression of the ANKR1 domain in melan-a cells also caused a dramatic reduction of Tyrp1 signals, whereas the VPS9 domain had no effect. Based on these findings, we propose that Varp functions as the Rab32/38 effector that controls trafficking of Tyrp1 in melanocytes.
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Affiliation(s)
- Kanako Tamura
- 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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Affiliation(s)
- Christina Wasmeier
- Molecular Medicine, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Alistair N. Hume
- Molecular Medicine, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Giulia Bolasco
- Molecular Medicine, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Miguel C. Seabra
- Molecular Medicine, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
- Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal
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Semenova I, Ikeda K, Ivanov P, Rodionov V. The protein kinase A-anchoring protein moesin is bound to pigment granules in melanophores. Traffic 2008; 10:153-60. [PMID: 18980611 DOI: 10.1111/j.1600-0854.2008.00852.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Major signaling cascades have been shown to play a role in the regulation of intracellular transport of organelles. In Xenopus melanophores, aggregation and dispersion of pigment granules are regulated by the second messenger cyclic AMP through the protein kinase A (PKA) signaling pathway. PKA is bound to pigment granules where it forms complexes with molecular motors involved in pigment transport. Association of PKA with pigment granules occurs through binding to A-kinase-anchoring proteins (AKAPs), whose identity remains largely unknown. In this study, we used mass spectrometry to examine an 80 kDa AKAP detected in preparations of purified pigment granules. We found that tryptic digests of granule protein fractions enriched in the 80 kDa AKAP contained peptides that corresponded to the actin-binding protein moesin, which has been shown to function as an AKAP in mammalian cells. We also found that recombinant Xenopus moesin interacted with PKA in vitro, copurified with pigment granules and bound to pigment granules in cells. Overexpression in melanophores of a mutant moesin lacking conserved PKA-binding domain did not affect aggregation of pigment granules but partially inhibited their dispersion. We conclude that Xenopus moesin is an AKAP whose PKA-scaffolding activity plays a role in the regulation of pigment dispersion in Xenopus melanophores.
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Affiliation(s)
- Irina Semenova
- Department of Cell Biology and Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06032-1507, USA
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Carlucci A, Lignitto L, Feliciello A. Control of mitochondria dynamics and oxidative metabolism by cAMP, AKAPs and the proteasome. Trends Cell Biol 2008; 18:604-13. [PMID: 18951795 DOI: 10.1016/j.tcb.2008.09.006] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 09/27/2008] [Accepted: 09/29/2008] [Indexed: 12/29/2022]
Abstract
Mitochondria are highly specialized organelles and major players in fundamental aspects of cell physiology. In yeast, energy metabolism and coupling of mitochondrial activity to growth and survival is controlled by the protein kinase A pathway. In higher eukaryotes, modulation of the so-called A-kinase anchor protein (AKAP) complex regulates mitochondrial dynamics and activity, adapting the oxidative machinery and the metabolic pathway to changes in physiological demand. Protein kinases and phosphatases are assembled by AKAPs within transduction units, providing a mechanism to control signaling events at mitochondria and other target organelles. Ubiquitin-mediated proteolysis of signal transducers and effectors provides an additional layer of complexity in the regulation of mitochondria homeostasis. Genetic evidence indicates that alteration of one or more components of these biochemical pathways leads to mitochondrial dysfunction and human diseases. In this review, we focus on the emerging role of AKAP scaffolds and the proteasome pathway in the control of oxidative metabolism, organelle dynamics and the mitochondrial signaling network. These aspects are crucial elements for maintaining a proper energy balance and cellular lifespan.
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Affiliation(s)
- Annalisa Carlucci
- Dipartimento di Biologia e Patologia Molecolare e Cellulare, Università Federico II, Naples, Italy
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Chapter 6 New Insights into Melanosome Transport in Vertebrate Pigment Cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 272:245-302. [DOI: 10.1016/s1937-6448(08)01606-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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