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Baker RP, Liu AZ, Casadevall A. Cell wall melanin impedes growth of the Cryptococcus neoformans polysaccharide capsule by sequestering calcium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599928. [PMID: 38948764 PMCID: PMC11212976 DOI: 10.1101/2024.06.20.599928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Cryptococcus neoformans has emerged as a frontrunner among deadly fungal pathogens and is particularly life-threatening for many HIV-infected individuals with compromised immunity. Multiple virulence factors contribute to the growth and survival of C. neoformans within the human host, the two most prominent of which are the polysaccharide capsule and melanin. As both of these features are associated with the cell wall, we were interested to explore possible cooperative or competitive interactions between these two virulence factors. Whereas capsule thickness had no effect on the rate at which cells became melanized, build-up of the melanin pigment layer resulted in a concomitant loss of polysaccharide material, leaving melanized cells with significantly thinner capsules than their non-melanized counterparts. When melanin was provided exogenously to cells in a transwell culture system we observed a similar inhibition of capsule growth and maintenance. Our results show that melanin sequesters calcium thereby limiting its availability to form divalent bridges between polysaccharide subunits required for outer capsule assembly. The decreased ability of melanized cells to incorporate exported polysaccharide into the growing capsule correlated with the amount of shed polysaccharide, which could have profound negative impacts on the host immune response. Significance Statement Cryptococcus neoformans is an opportunistic fungal pathogen that presents a significant health risk for immunocompromised individuals. We report an interaction between the two major cryptococcal virulence factors, the polysaccharide capsule and melanin. Melanin impacted the growth and maintenance of the polysaccharide capsule, resulting in loss of capsular material during melanization. Our results suggest that melanin can act as a sink for calcium, thereby limiting its availability to form ionic bridges between polysaccharide chains on the growing surface of the outer capsule. As polysaccharide is continuously exported to support capsule growth, failure of melanized cells to incorporate this material results in a higher concentration of shed polysaccharide in the extracellular milieu, which is expected to interfere with host immunity.
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Xie Y, Wu N, Tang S, Zhou Z, Chen J, Li J, Wu F, Xu M, Xu X, Liu Y, Ma X. Endoplasmic Reticulum Dysfunction: An Emerging Mechanism of Vitiligo Pathogenesis. Clin Cosmet Investig Dermatol 2024; 17:1133-1144. [PMID: 38774812 PMCID: PMC11107934 DOI: 10.2147/ccid.s459070] [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: 01/24/2024] [Accepted: 04/25/2024] [Indexed: 05/24/2024]
Abstract
The endoplasmic reticulum (ER) is the main site of protein synthesis, transport, and modification. Its abnormal status has now emerged as an established cause of many pathological processes, such as tumors and autoimmune diseases. Recent studies also demonstrated that the defective functions of ER may lead to pigmentary diseases. Vitiligo is a depigmenting ailment skin disorder whose pathogenesis is now found to be associated with ER. However, the detailed mechanism is still unclear. In this review, we try to link the association between ER with its inter- and intra-organellar interactions in vitiligo pathogenesis and focus on the function, mechanism, and clinical potential of ER with vitiligo. Expand ER is found in melanocytes of vitiligo and ER stress (ERS) might be a bridge between oxidative stress and innate and adaptive immunity. Meanwhile, the tight association between ER and mitochondria or melanosomes in organelles levels, as well as genes and cytokines, is the new paradigm in the pathogenesis of vitiligo. This undoubtedly adds a new aspect to the understanding of vitiligo, facilitating the design of targeted therapies for vitiligo.
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Affiliation(s)
- Yongyi Xie
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Nanhui Wu
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Suwei Tang
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Zhiyu Zhou
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Jiashe Chen
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Jie Li
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Fei Wu
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Mingyuan Xu
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Xiaoxiang Xu
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Yeqiang Liu
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
| | - Xin Ma
- Shanghai Skin Disease Hospital, Institute of Dermatology, School of Medicine, Tongji University, Shanghai, People’s Republic of China
- Department of Dermatology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China
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Kaushik H, Kumar V, Parsad D. Mitochondria-Melanocyte cellular interactions: An emerging mechanism of vitiligo pathogenesis. J Eur Acad Dermatol Venereol 2023; 37:2196-2207. [PMID: 36897230 DOI: 10.1111/jdv.19019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 02/07/2023] [Indexed: 03/11/2023]
Abstract
Mitochondria has emerged as a potential modulator of melanocyte function other than just meeting its cellular ATP demands. Mitochondrial DNA defects are now an established cause of maternal inheritance diseases. Recent cellular studies have highlighted the mitochondrial interaction with other cellular organelles that lead to disease conditions such as in Duchenne muscular dystrophy, where defective mitochondria was found in melanocytes of these patients. Vitiligo, a depigmentory ailment of the skin, is another such disorder whose pathogenesis is now found to be associated with mitochondria. The complete absence of melanocytes at the lesioned site in vitiligo is a fact; however, the precise mechanism of this destruction is still undefined. In this review we have tried to discuss and link the emerging facts of mitochondrial function or its inter- and intra-organellar communications in vitiligo pathogenesis. Mitochondrial close association with melanosomes, molecular involvement in melanocyte-keratinocyte communication and melanocyte survival are new paradigm of melanogenesis that could ultimately account for vitiligo. This definitely adds the new dimensions to our understanding of vitiligo, its management and designing of future mitochondrial targeted therapy for vitiligo.
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Affiliation(s)
- Hitaishi Kaushik
- Department of Dermatology, Venereology & Leprology, PGIMER, Chandigarh, 160012, India
| | - Vinod Kumar
- Department of Dermatology, Venereology & Leprology, PGIMER, Chandigarh, 160012, India
| | - Davinder Parsad
- Department of Dermatology, Venereology & Leprology, PGIMER, Chandigarh, 160012, India
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Fernandes B, Cavaco-Paulo A, Matamá T. A Comprehensive Review of Mammalian Pigmentation: Paving the Way for Innovative Hair Colour-Changing Cosmetics. BIOLOGY 2023; 12:biology12020290. [PMID: 36829566 PMCID: PMC9953601 DOI: 10.3390/biology12020290] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/26/2023] [Accepted: 02/09/2023] [Indexed: 02/15/2023]
Abstract
The natural colour of hair shafts is formed at the bulb of hair follicles, and it is coupled to the hair growth cycle. Three critical processes must happen for efficient pigmentation: (1) melanosome biogenesis in neural crest-derived melanocytes, (2) the biochemical synthesis of melanins (melanogenesis) inside melanosomes, and (3) the transfer of melanin granules to surrounding pre-cortical keratinocytes for their incorporation into nascent hair fibres. All these steps are under complex genetic control. The array of natural hair colour shades are ascribed to polymorphisms in several pigmentary genes. A myriad of factors acting via autocrine, paracrine, and endocrine mechanisms also contributes for hair colour diversity. Given the enormous social and cosmetic importance attributed to hair colour, hair dyeing is today a common practice. Nonetheless, the adverse effects of the long-term usage of such cosmetic procedures demand the development of new methods for colour change. In this context, case reports of hair lightening, darkening and repigmentation as a side-effect of the therapeutic usage of many drugs substantiate the possibility to tune hair colour by interfering with the biology of follicular pigmentary units. By scrutinizing mammalian pigmentation, this review pinpoints key targetable processes for the development of innovative cosmetics that can safely change the hair colour from the inside out.
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Affiliation(s)
- Bruno Fernandes
- CEB—Centre of Biological Engineering, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
| | - Artur Cavaco-Paulo
- CEB—Centre of Biological Engineering, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
- LABBELS—Associate Laboratory, 4710-057 Braga, Portugal
- Correspondence: (A.C.-P.); (T.M.); Tel.: +351-253-604-409 (A.C.-P.); +351-253-601-599 (T.M.)
| | - Teresa Matamá
- CEB—Centre of Biological Engineering, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
- LABBELS—Associate Laboratory, 4710-057 Braga, Portugal
- Correspondence: (A.C.-P.); (T.M.); Tel.: +351-253-604-409 (A.C.-P.); +351-253-601-599 (T.M.)
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Synchronized Cardiac Impulses Emerge From Heterogeneous Local Calcium Signals Within and Among Cells of Pacemaker Tissue. JACC Clin Electrophysiol 2021; 6:907-931. [PMID: 32819526 DOI: 10.1016/j.jacep.2020.06.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/19/2020] [Accepted: 06/24/2020] [Indexed: 12/11/2022]
Abstract
OBJECTIVES This study sought to identify subcellular Ca2+ signals within and among cells comprising the sinoatrial node (SAN) tissue. BACKGROUND The current paradigm of SAN impulse generation: 1) is that full-scale action potentials (APs) of a common frequency are initiated at 1 site and are conducted within the SAN along smooth isochrones; and 2) does not feature fine details of Ca2+ signaling present in isolated SAN cells, in which small subcellular, subthreshold local Ca2+ releases (LCRs) self-organize to generate cell-wide APs. METHODS Immunolabeling was combined with a novel technique to detect the occurrence of LCRs and AP-induced Ca2+ transients (APCTs) in individual pixels (chronopix) across the entire mouse SAN images. RESULTS At high magnification, Ca2+ signals appeared markedly heterogeneous in space, amplitude, frequency, and phase among cells comprising an HCN4+/CX43- cell meshwork. The signaling exhibited several distinguishable patterns of LCR/APCT interactions within and among cells. Rhythmic APCTs that were apparently conducted within the meshwork were transferred to a truly conducting HCN4-/CX43+ network of striated cells via narrow functional interfaces where different cell types intertwine, that is, the SAN anatomic/functional unit. At low magnification, the earliest APCT of each cycle occurred within a small area of the HCN4 meshwork, and subsequent APCT appearance throughout SAN pixels was discontinuous and asynchronous. CONCLUSIONS The study has discovered a novel, microscopic Ca2+ signaling paradigm of SAN operation that has escaped detection using low-resolution, macroscopic tissue isochrones employed in prior studies: synchronized APs emerge from heterogeneous subcellular subthreshold Ca2+ signals, resembling multiscale complex processes of impulse generation within clusters of neurons in neuronal networks.
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Gamma-Aminobutyric Acid (GABA) Inhibits α-Melanocyte-Stimulating Hormone-Induced Melanogenesis through GABA A and GABA B Receptors. Int J Mol Sci 2021; 22:ijms22158257. [PMID: 34361022 PMCID: PMC8347673 DOI: 10.3390/ijms22158257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 11/25/2022] Open
Abstract
Gamma-aminobutyric acid (GABA) is considered the primary inhibitory neurotransmitter in the human cortex. However, whether GABA regulates melanogenesis has not been comprehensively elucidated. In this study, we reveal that GABA (20 mM) significantly inhibited α-melanocyte-stimulating hormone (α-MSH)-induced extracellular (from 354.9% ± 28.4% to 126.5% ± 16.0%) and intracellular melanin contents (from 236.7% ± 11.1% to 102.7% ± 23.1%) in B16F10 melanoma cells, without inducing cytotoxicity. In addition, α-MSH-induced hyperpigmentation in zebrafish larvae was inhibited from 246.3% ± 5.4% to 116.3% ± 3.1% at 40 mM GABA, displaying no apparent cardiotoxicity. We also clarify that the GABA-mediated antimelanogenic properties were related to the direct inhibition of microphthalmia-associated transcription factor (MITF) and tyrosinase expression by inhibiting cyclic adenosine monophosphate (cAMP) and cAMP response element-binding protein (CREB). Furthermore, under α-MSH stimulation, GABA-related antimelanogenic effects were mediated through the GABAA and GABAB receptors, with subsequent inhibition of Ca2+ accumulation. In B16F10 melanoma cells and zebrafish larvae, pretreatment with bicuculline, a GABAA receptor antagonist, and CGP 46381, a GABAB receptor antagonist, reversed the antimelanogenic effect of GABA following α-MSH treatment by upregulating Ca2+ accumulation. In conclusion, our results indicate that GABA inhibits α-MSH-induced melanogenesis. Hence, in addition to the health benefits of GABA in the central nervous system, it could ameliorate hyperpigmentation disorders.
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Wiriyasermkul P, Moriyama S, Nagamori S. Membrane transport proteins in melanosomes: Regulation of ions for pigmentation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183318. [PMID: 32333855 PMCID: PMC7175901 DOI: 10.1016/j.bbamem.2020.183318] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/17/2020] [Accepted: 04/18/2020] [Indexed: 12/12/2022]
Abstract
Melanosomes are unique organelles in melanocytes that produce melanin, the pigment for skin, hair, and eye color. Tyrosinase is the essential and rate-limiting enzyme for melanin production, that strictly requires neutral pH for activity. pH maintenance is a result of the combinational function of multiple ion transport proteins. Thus, ion homeostasis in melanosomes is crucial for melanin synthesis. Defect of the ion transport system causes various pigmentation phenotypes, from mild effect to severe disorders such as albinism. In this review, we summarize the up-to-date knowledge of the ion transport system, such as transport function, structure, and the physiological roles and mechanisms of the ion transport proteins in melanosomes. In addition, we propose a model of melanosomal ion transport system-how the functional coupling of multiple transport proteins modulates and maintains ion homeostasis. We discuss melanin synthesis in terms of the ion transport system.
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Affiliation(s)
- Pattama Wiriyasermkul
- Department of Collaborative Research for Bio-Molecular Dynamics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan
| | - Satomi Moriyama
- Department of Collaborative Research for Bio-Molecular Dynamics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan
| | - Shushi Nagamori
- Department of Collaborative Research for Bio-Molecular Dynamics, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan.
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8
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Zhang Z, Gong J, Sviderskaya EV, Wei A, Li W. Mitochondrial NCKX5 regulates melanosomal biogenesis and pigment production. J Cell Sci 2019; 132:jcs232009. [PMID: 31201282 PMCID: PMC6679581 DOI: 10.1242/jcs.232009] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/03/2019] [Indexed: 01/02/2023] Open
Abstract
Oculocutaneous albinism (OCA) is a heterogeneous and autosomal recessive hypopigmentation disorder, which is caused by mutations of genes involved in pigment biosynthesis or melanosome biogenesis. We have previously identified NCKX5 (also known as SLC24A5) as a causative gene for OCA type 6 (OCA6). However, the pathogenesis of OCA6 is unknown. We found that NCKX5 is localized to mitochondria, not to melanosomes. Pharmacological inhibition of mitochondrial function or NCKX exchanger activity reduced pigment production. Loss of NCKX5 attenuated Ca2+ enrichment in melanosomes, which compromised PMEL fibril formation, melanosome maturation and pigment production. Thus, we have defined a new class of hypopigmentation attributable to dysfunctional mitochondria and an impairment of mitochondrial Ca2+ transfer into melanosomes. Thus, it is possible that mitochondrial function could have a role in the graying of hair in older people and formation of hypopigmented lesions in vitiligo patients.
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Affiliation(s)
- Zhao Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control Center, National Center for Children's Health; Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
- University of Chinese Academy of Sciences, Beijing 100039, China
| | - Juanjuan Gong
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control Center, National Center for Children's Health; Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
| | - Elena V Sviderskaya
- Cell Signalling Research Centre, St. George's, University of London, London SW17 0RE, UK
| | - Aihua Wei
- Department of Dermatology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China
| | - Wei Li
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control Center, National Center for Children's Health; Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
- Shunyi Women and Children's Hospital of Beijing Children's Hospital, Beijing 101300, China
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9
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Hasse S, Müller MC, Schallreuter KU, von Woedtke T. Stimulation of melanin synthesis in melanoma cells by cold plasma. Biol Chem 2018; 400:101-109. [DOI: 10.1515/hsz-2018-0223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 10/30/2018] [Indexed: 11/15/2022]
Abstract
Abstract
Skin color is derived from epidermal melanocytes that contain specialized organelles in which melanin is formed. The formation of melanin is a well-orchestrated process, and reactive oxygen species (ROS) play a role in numerous enzymatic conversions, such as the reactions catalyzed by tyrosinase and tyrosine hydroxylase. Currently, there is ample evidence that cold plasma exerts biological effects on cells through the impact of ROS and reactive nitrogen species (RNS). Modulation of melanin biosynthesis by cold plasma has not yet been investigated. This study investigated melanin biosynthesis of human melanoma cell lines with different endogenous melanin contents (SK-Mel 28, G-361, FM-55-P and MNT-1) in response to cold plasma-derived reactive species. Initially, the distribution of melanosomes, via immunofluorescence, and the influence of microphthalmia-associated transcription factor (MiTF), as a key transcription factor, was investigated. In our experimental setup, all of the tested cell lines had an elevated melanin content after exposure to cold plasma. These promising results suggest a novel potential application of cold plasma for the regulation of melanogenesis and may be a useful tool for influencing skin color in the future.
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Affiliation(s)
- Sybille Hasse
- Department Plasma Life Science , Leibniz-Institute for Plasma Science and Technology (INP) , Felix-Hausdorff-Str. 2 , D-17489 Greifswald , Germany
| | - Marie-Christine Müller
- Department Plasma Life Science , Leibniz-Institute for Plasma Science and Technology (INP) , Felix-Hausdorff-Str. 2 , D-17489 Greifswald , Germany
| | - Karin Uta Schallreuter
- Institute for Pigmentary Disorders e.V. , Walther-Rathenau-Str. 49a , D-17489 Greifswald , Germany
| | - Thomas von Woedtke
- Department Plasma Life Science , Leibniz-Institute for Plasma Science and Technology (INP) , Felix-Hausdorff-Str. 2 , D-17489 Greifswald , Germany
- Institute for Hygiene and Environmental Medicine, University Medicine Greifswald , Ferdinand-Sauerbruch-Str. , D-17475 Greifswald , Germany
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10
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Kyrmizi I, Ferreira H, Carvalho A, Figueroa JAL, Zarmpas P, Cunha C, Akoumianaki T, Stylianou K, Deepe GS, Samonis G, Lacerda JF, Campos A, Kontoyiannis DP, Mihalopoulos N, Kwon-Chung KJ, El-Benna J, Valsecchi I, Beauvais A, Brakhage AA, Neves NM, Latge JP, Chamilos G. Calcium sequestration by fungal melanin inhibits calcium-calmodulin signalling to prevent LC3-associated phagocytosis. Nat Microbiol 2018; 3:791-803. [PMID: 29849062 DOI: 10.1038/s41564-018-0167-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 04/23/2018] [Indexed: 11/09/2022]
Abstract
LC3-associated phagocytosis (LAP) is a non-canonical autophagy pathway regulated by Rubicon, with an emerging role in immune homeostasis and antifungal host defence. Aspergillus cell wall melanin protects conidia (spores) from killing by phagocytes and promotes pathogenicity through blocking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent activation of LAP. However, the signalling regulating LAP upstream of Rubicon and the mechanism of melanin-induced inhibition of this pathway remain incompletely understood. Herein, we identify a Ca2+ signalling pathway that depends on intracellular Ca2+ sources from endoplasmic reticulum, endoplasmic reticulum-phagosome communication, Ca2+ release from phagosome lumen and calmodulin (CaM) recruitment, as a master regulator of Rubicon, the phagocyte NADPH oxidase NOX2 and other molecular components of LAP. Furthermore, we provide genetic evidence for the physiological importance of Ca2+-CaM signalling in aspergillosis. Finally, we demonstrate that Ca2+ sequestration by Aspergillus melanin inside the phagosome abrogates activation of Ca2+-CaM signalling to inhibit LAP. These findings reveal the important role of Ca2+-CaM signalling in antifungal immunity and identify an immunological function of Ca2+ binding by melanin pigments with broad physiological implications beyond fungal disease pathogenesis.
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Affiliation(s)
- Irene Kyrmizi
- Department of Medicine, University of Crete, Heraklion, Crete, Greece.,Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece
| | - Helena Ferreira
- 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Guimarães, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Agostinho Carvalho
- ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.,Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus de Gualtar, Braga, Portugal
| | - Julio Alberto Landero Figueroa
- Department of Chemistry, University of Cincinnati/Agilent Technologies Metallomics Center of the Americas, University of Cincinnati, Cincinnati, OH, USA
| | - Pavlos Zarmpas
- Department of Chemistry, University of Crete, Heraklion, Crete, Greece
| | - Cristina Cunha
- ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.,Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus de Gualtar, Braga, Portugal
| | - Tonia Akoumianaki
- Department of Medicine, University of Crete, Heraklion, Crete, Greece
| | - Kostas Stylianou
- Department of Medicine, University of Crete, Heraklion, Crete, Greece
| | - George S Deepe
- Division of Infectious Diseases, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - George Samonis
- Department of Medicine, University of Crete, Heraklion, Crete, Greece
| | - João F Lacerda
- Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisbon, Portugal.,Serviço de Hematologia e Transplantação de Medula, Hospital de Santa Maria, Lisbon, Portugal
| | - António Campos
- Serviço de Transplantação de Medula Óssea (STMO), Instituto Português de Oncologia do Porto, Porto, Portugal
| | - Dimitrios P Kontoyiannis
- Department of Infectious Diseases, The University of Texas, MD Anderson Cancer Center, Austin, TX, USA
| | | | - Kyung J Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Jamel El-Benna
- INSERM-U1149, CNRS-ERL8252, Centre de Recherche sur l'Inflammation, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Laboratoire d'Excellence Inflamex, DHU FIRE, Faculté de Médecine, Site Xavier Bichat, Paris, France
| | | | - Anne Beauvais
- Unité des Aspergillus, Institut Pasteur, Paris, France
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz-Institute for Natural Product Research and Infection Biology (HKI) and Friedrich Schiller University, Jena, Germany
| | - Nuno M Neves
- 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Guimarães, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | | | - Georgios Chamilos
- Department of Medicine, University of Crete, Heraklion, Crete, Greece. .,Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece.
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11
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Knörle R. Neuromelanin in Parkinson's Disease: from Fenton Reaction to Calcium Signaling. Neurotox Res 2017; 33:515-522. [PMID: 28879408 DOI: 10.1007/s12640-017-9804-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/14/2017] [Accepted: 08/23/2017] [Indexed: 12/13/2022]
Abstract
Neuromelanin is supposed to play a key role in the pathogenesis of Parkinson's disease. A common theory is the formation of reactive oxygen species through the Fenton reaction catalyzed by neuromelanin-bound iron ions and subsequent death of the dopaminergic cells in the substantia nigra. From a physicochemical point of view, this pathway is rather implausible: a highly reactive radical built within a powerful radical scavenger would more promptly be inactivated before it might diffuse within the cell to reach a target to exert its deleterious potential. This review of the literature provides evidence for an interaction of neuromelanin with the calcium signaling pathway in Parkinson's disease and expands the view of the pathophysiological contribution of neuromelanin towards a cytoprotective involvement of this macromolecule in the calcium signaling system. More probably than being directly involved in the production of reactive oxygen species, neuromelanin may act as a calcium reservoir and thus protect dopaminergic cells from cell death. A loss of neuromelanin, as observed in the substantia nigra of Parkinson patients, would lead to enhanced calcium messaging through the loss of an important calcium reservoir and thus finally via the formation of reactive oxygen species to cell death within the substantia nigra.
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Affiliation(s)
- Rainer Knörle
- IBAM GbR Dr. Rainer Knörle Dr. Peter Schnierle, Ferdinand-Porsche-Str. 5, 79211, Denzlingen, Germany.
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12
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da Silva LP, Oliveira S, Pirraco RP, Santos TC, Reis RL, Marques AP, Correlo VM. Eumelanin-releasing spongy-like hydrogels for skin re-epithelialization purposes. ACTA ACUST UNITED AC 2017; 12:025010. [PMID: 28181477 DOI: 10.1088/1748-605x/aa5f79] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Melanin function in the skin has been associated with pigmentation but other properties such as electrical conductance, photoprotection, and antioxidant and antimicrobial activity have also been recognized. Nonetheless, the use of melanin in a skin wound healing context has never been considered. In this sense, eumelanin particles with a typical round and nano-sized morphology and electrical conductivity of 2.09 × 10-8 S cm-1 were extracted from the ink of Sepia officinalis. The ability of primary human keratinocytes (hKCs) to phagocyte eumelanin, which was then accumulated in cytosolic vesicles and nuclei surroundings, was demonstrated. Keratinocyte viability and maturation was not affected by eumelanin contact, but at eumelanin amounts higher than 0.1 mg l-1 cell morphology was altered and cell proliferation was inhibited. A time and eumelanin amount-dependent reduction of reactive oxygen species (ROS) released by eumelanin-containing ultraviolet (UV)-irradiated keratinocytes was observed. Eumelanin-containing gellan gum (GG) spongy-like hydrogels allowed a sustained release of eumelanin in the range of 0.1 to 5 mg l-1, which was shown in vitro to not be harmful to hKCs, and the absence of a strong host reaction after subcutaneous implantation in mice. Herein, we propose spongy-like hydrogels as sustained release matrices of S. officinalis eumelanin for predicting a beneficial role in skin wound healing through a direct effect over keratinocytes.
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Affiliation(s)
- Lucília P da Silva
- 3B's Research Group-Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque da Ciência e Tecnologia, 4805-017 Barco, Taipas, Guimarães, Portugal. ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
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Tsai WC, Chan YH, Hsueh CH, Everett TH, Chang PC, Choi EK, Olaopa MA, Lin SF, Shen C, Kudela MA, Rubart-von der Lohe M, Chen Z, Jadiya P, Tomar D, Luvison E, Anzalone N, Patel VV, Chen PS. Small conductance calcium-activated potassium current and the mechanism of atrial arrhythmia in mice with dysfunctional melanocyte-like cells. Heart Rhythm 2016; 13:1527-35. [PMID: 26961301 DOI: 10.1016/j.hrthm.2016.03.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Indexed: 01/02/2023]
Abstract
BACKGROUND The melanin synthesis enzyme dopachrome tautomerase (Dct) regulates intracellular Ca(2+) in melanocytes. Homozygous Dct knockout (Dct(-/-)) adult mice are vulnerable to atrial arrhythmias (AA). OBJECTIVE The purpose of this study was to determine whether apamin-sensitive small conductance Ca(2+)-activated K(+) (SK) currents are upregulated in Dct(-/-) mice and contribute to AA. METHODS Optical mapping was used to study the membrane potential of the right atrium in Langendorff perfused Dct(-/-) (n = 9) and Dct(+/-) (n = 9) mice. RESULTS Apamin prolonged action potential duration (APD) by 18.8 ms (95% confidence interval [CI] 13.4-24.1 ms) in Dct(-/-) mice and by 11.5 ms (95% CI 5.4-17.6 ms) in Dct(+/-) mice at a pacing cycle length of 150 ms (P = .047). The pacing cycle length threshold to induce APD alternans was 48 ms (95% CI 34-62 ms) for Dct(-/-) mice and 21 ms (95% CI 12-29 ms) for Dct(+/-) mice (P = .002) at baseline, and it was 35 ms (95% CI 21-49 ms) for Dct(-/-) mice and 22 ms (95% CI 11-32 ms) for Dct(+/-) mice (P = .025) after apamin administration. Apamin prolonged post-burst pacing APD by 8.9 ms (95% CI 3.9-14.0 ms) in Dct(-/-) mice and by 1.5 ms (95% CI 0.7-2.3 ms) in Dct(+/-) mice (P = .005). Immunoblot and quantitative polymerase chain reaction analyses showed that protein and transcripts levels of SK1 and SK3 were increased in the right atrium of Dct(-/-) mice. AA inducibility (89% vs 11%; P = .003) and duration (281 seconds vs 66 seconds; P = .008) were greater in Dct(-/-) mice than in Dct(+/-) mice at baseline, but not different (22% vs 11%; P = 1.00) after apamin administration. Five of 8 (63%) induced atrial fibrillation episodes in Dct(-/-) mice had focal drivers. CONCLUSION Apamin-sensitive SK current upregulation in Dct(-/-) mice plays an important role in the mechanism of AA.
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Affiliation(s)
- Wei-Chung Tsai
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yi-Hsin Chan
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Chia-Hsiang Hsueh
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California
| | - Thomas H Everett
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Po-Cheng Chang
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Eue-Keun Choi
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Michael A Olaopa
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Shien-Fong Lin
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Institute of Biomedical Engineering, National Chiao-Tung University, Hsin-Chu, Taiwan
| | - Changyu Shen
- Department of Biostatistics, Indiana University School of Medicine and the Fairbanks School of Public Health, Indianapolis, Indiana
| | - Maria Aleksandra Kudela
- Department of Biostatistics, Indiana University School of Medicine and the Fairbanks School of Public Health, Indianapolis, Indiana
| | | | - Zhenhui Chen
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Pooja Jadiya
- Cardiovascular Research Center, Department of Physiology, Section of Clinical Cardiac Electrophysiology, Philadelphia, Pennsylvania
| | - Dhanendra Tomar
- Center for Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Emily Luvison
- Cardiovascular Research Center, Department of Physiology, Section of Clinical Cardiac Electrophysiology, Philadelphia, Pennsylvania
| | - Nicholas Anzalone
- Cardiovascular Research Center, Department of Physiology, Section of Clinical Cardiac Electrophysiology, Philadelphia, Pennsylvania
| | - Vickas V Patel
- Cardiovascular Research Center, Department of Physiology, Section of Clinical Cardiac Electrophysiology, Philadelphia, Pennsylvania,; Center for Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Peng-Sheng Chen
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.
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Lipid transfer and metabolism across the endolysosomal-mitochondrial boundary. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:880-894. [PMID: 26852832 DOI: 10.1016/j.bbalip.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/30/2016] [Accepted: 02/03/2016] [Indexed: 01/10/2023]
Abstract
Lysosomes and mitochondria occupy a central stage in the maintenance of cellular homeostasis, by playing complementary roles in nutrient sensing and energy metabolism. Specifically, these organelles function as signaling hubs that integrate environmental and endogenous stimuli with specific metabolic responses. In particular, they control various lipid biosynthetic and degradative pipelines, either directly or indirectly, by regulating major cellular metabolic pathways, and by physical and functional connections established with each other and with other organelles. Membrane contact sites allow the exchange of ions and molecules between organelles, even without membrane fusion, and are privileged routes for lipid transfer among different membrane compartments. These inter-organellar connections typically involve the endoplasmic reticulum. Direct membrane contacts have now been described also between lysosomes, autophagosomes, lipid droplets, and mitochondria. This review focuses on these recently identified membrane contact sites, and on their role in lipid biosynthesis, exchange, turnover and catabolism. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Riley PA, Stratford MR. Oxidative calcium release from catechol. Bioorg Med Chem Lett 2015; 25:1453-4. [DOI: 10.1016/j.bmcl.2015.02.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 02/15/2015] [Accepted: 02/16/2015] [Indexed: 11/30/2022]
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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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17
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Daniele T, Hurbain I, Vago R, Casari G, Raposo G, Tacchetti C, Schiaffino MV. Mitochondria and melanosomes establish physical contacts modulated by Mfn2 and involved in organelle biogenesis. Curr Biol 2014; 24:393-403. [PMID: 24485836 DOI: 10.1016/j.cub.2014.01.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 11/15/2013] [Accepted: 01/03/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND To efficiently supply ATP to sites of high-energy demand and finely regulate calcium signaling, mitochondria adapt their metabolism, shape, and distribution within the cells, including relative positioning with respect to other organelles. However, physical contacts between mitochondria and the secretory/endocytic pathway have been demonstrated so far only with the ER, through structural and functional interorganellar connections. RESULTS Here we show by electron tomography that mitochondria physically contact melanosomes, specialized lysosome-related organelles of pigment cells, through fibrillar bridges resembling the protein tethers linking mitochondria and the ER. Mitofusin (Mfn) 2, which bridges ER to mitochondria, specifically localizes also to melanosome-mitochondrion contacts, and its knockdown significantly reduces the interorganellar connections. Contacts are associated to the melanogenesis process, as indicated by the fact that they are reduced in a model of aberrant melanogenesis whereas they are enhanced both where melanosome biogenesis takes place in the perinuclear area and when it is actively stimulated by OA1, a G protein-coupled receptor implicated in ocular albinism and organellogenesis. Consistently, Mfn2 knockdown prevents melanogenesis activation by OA1, and the pharmacological inhibition of mitochondrial ATP synthesis severely reduces contact formation and impairs melanosome biogenesis, by affecting in particular the developing organelles showing the highest frequency of contacts. CONCLUSIONS Altogether, our findings reveal the presence of an unprecedented physical and functional connection between mitochondria and the secretory/endocytic pathway that goes beyond the ER-mitochondria linkage and is spatially and timely associated to secretory organelle biogenesis.
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Affiliation(s)
- Tiziana Daniele
- Organelle Biogenesis and Motility Unit, Center for Translational Genomics and Bioinformatics, San Raffaele Scientific Institute, 20132 Milan, Italy; Experimental Imaging Center, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Ilse Hurbain
- Institut Curie, Centre de Recherche, Paris 75248, France; Structure and Membrane Compartments CNRS UMR144, Paris 75248, France; Cell and Tissue Imaging Facility (PICT-IBiSA) CNRS UMR144, Paris 75248, France
| | - Riccardo Vago
- Vita-Salute San Raffaele University, 20132 Milan, Italy; Neurogenomics Unit, Center for Translational Genomics and Bioinformatics, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Giorgio Casari
- Vita-Salute San Raffaele University, 20132 Milan, Italy; Neurogenomics Unit, Center for Translational Genomics and Bioinformatics, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Graça Raposo
- Institut Curie, Centre de Recherche, Paris 75248, France; Structure and Membrane Compartments CNRS UMR144, Paris 75248, France; Cell and Tissue Imaging Facility (PICT-IBiSA) CNRS UMR144, Paris 75248, France
| | - Carlo Tacchetti
- Experimental Imaging Center, San Raffaele Scientific Institute, 20132 Milan, Italy; Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy
| | - Maria Vittoria Schiaffino
- Organelle Biogenesis and Motility Unit, Center for Translational Genomics and Bioinformatics, San Raffaele Scientific Institute, 20132 Milan, Italy.
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Orai-STIM-mediated Ca2+ release from secretory granules revealed by a targeted Ca2+ and pH probe. Proc Natl Acad Sci U S A 2012. [PMID: 23184982 DOI: 10.1073/pnas.1218247109] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Secretory granules (SGs) sequester significant calcium. Understanding roles for this calcium and potential mechanisms of release is hampered by the difficulty of measuring SG calcium directly in living cells. We adapted the Förster resonance energy transfer-based D1-endoplasmic reticulum (ER) probe to develop a unique probe (D1-SG) to measure calcium and pH in secretory granules. It significantly localizes to SGs and reports resting free Ca(2+) of 69 ± 15 μM and a pH of 5.8. Application of extracellular ATP to activate P2Y receptors resulted in a slow monotonic decrease in SG Ca(2+) temporally correlated with the occurrence of store-operated calcium entry (SOCE). Further investigation revealed a unique receptor-mediated mechanism of calcium release from SGs that involves SG store-operated Orai channels activated by their regulator stromal interaction molecule 1 (STIM1) on the ER. SG Ca(2+) release is completely antagonized by a SOCE antagonist, by switching to Ca(2+)-free medium, and by overexpression of a dominant-negative Orai1(E106A). Overexpression of the CRAC activation domain (CAD) of STIM1 resulted in a decrease of resting SG Ca(2+) by ∼75% and completely abolished the ATP-mediated release of Ca(2+) from SGs. Overexpression of a dominant-negative CAD construct(CAD-A376K) induced no significant changes in SG Ca(2+). Colocalization analysis suggests that, like the plasma membrane, SG membranes also possess Orai1 channels and that during SG Ca(2+) release, colocalization between SGs and STIM1 increases. We propose Orai channel opening on SG membranes as a potential mode of calcium release from SGs that may serve to raise local cytoplasmic calcium concentrations and aid in refilling intracellular calcium stores of the ER and exocytosis.
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Melanin-based coatings as lead-binding agents. Bioinorg Chem Appl 2012; 2012:361803. [PMID: 22611345 PMCID: PMC3350951 DOI: 10.1155/2012/361803] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Revised: 01/23/2012] [Accepted: 02/07/2012] [Indexed: 11/26/2022] Open
Abstract
Interactions between metal ions and different forms of melanin play significant roles in melanin biochemistry. The binding properties of natural melanin and related synthetic materials can be exploited for nonbiological applications, potentially including water purification. A method for investigating metal ion-melanin interactions on solid support is described, with lead as the initial target. 2.5 cm discs of the hydrophobic polymer PVDF were coated with synthetic eumelanin from the tyrosinase-catalyzed polymerization of L-dopa, and with melanin extracted from human hair. Lead (Pb2+) binding was quantified by atomic absorption spectroscopy (flame mode), and the data was well fit by the Langmuir model. Langmuir affinities ranged from 3.4 · 103 to 2.2 · 104 M−1. At the maximum capacity observed, the synthetic eumelanin coating bound ~9% of its mass in lead. Binding of copper (Cu2+), zinc (Zn2+), and cadmium (Cd2+) to the synthetic-eumelanin-coated discs was also investigated. Under the conditions tested, the Langmuir affinities for Zn2+, Cd2+, and Cu2+ were 35%, 53%, and 77%, respectively, of the Langmuir affinity for Pb2+. The synthetic-eumelanin-coated discs have a slightly higher capacity for Cu2+ on a per mole basis than for Pb2+, and lower capacities for Cd2+ and Zn2+. The system described can be used to address biological questions and potentially be applied toward melanin-based water purification.
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20
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Photodynamic therapy-induced killing is enhanced in depigmented metastatic melanoma cells. Cell Biol Int 2012; 35:939-44. [PMID: 21542806 DOI: 10.1042/cbi20110103] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The resistance of pigmented human melanomas over their unpigmented counterparts to a number of therapies has suggested that the presence of intracellular melanin plays a role in rendering these cells less susceptible to cell death, probably through the ability of this pigment to act as an intracellular antioxidant, thus neutralizing chemotherapeutic-induced ROS (reactive oxygen species). PDT (photodynamic therapy) was recently suggested as an attractive, adjunctive therapy owing to its cellular specificity and limited side effects. In the present study, we propose that first depigmenting melanomas with a reversible TYR (tyrosinase) inhibitor such as PTU (phenylthiourea) increases their susceptibility to HYP-PDT (hypericin-mediated PDT). Pigmented [UCT Mel-1 (University of Cape Town melanoma cell line 1)] and unpigmented (A375) melanomas were first characterized with respect to their TYR activities and melanin quantities and then treated with a TYR inhibitor for 48 h. Cell viability assays after treatment with 3 μM HYP-PDT showed a significant increase in cell death in depigmented melanomas compared with untreated melanomas that returned to the level of untreated melanoma cells on removing the TYR inhibitor. The present study supports the hypothesis that combining the inhibition of melanogenesis with PDT should be explored as a valid therapeutic target for the management of advanced melanoma.
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21
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Molecular mechanisms of endolysosomal Ca2+ signalling in health and disease. Biochem J 2011; 439:349-74. [PMID: 21992097 DOI: 10.1042/bj20110949] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endosomes, lysosomes and lysosome-related organelles are emerging as important Ca2+ storage cellular compartments with a central role in intracellular Ca2+ signalling. Endocytosis at the plasma membrane forms endosomal vesicles which mature to late endosomes and culminate in lysosomal biogenesis. During this process, acquisition of different ion channels and transporters progressively changes the endolysosomal luminal ionic environment (e.g. pH and Ca2+) to regulate enzyme activities, membrane fusion/fission and organellar ion fluxes, and defects in these can result in disease. In the present review we focus on the physiology of the inter-related transport mechanisms of Ca2+ and H+ across endolysosomal membranes. In particular, we discuss the role of the Ca2+-mobilizing messenger NAADP (nicotinic acid adenine dinucleotide phosphate) as a major regulator of Ca2+ release from endolysosomes, and the recent discovery of an endolysosomal channel family, the TPCs (two-pore channels), as its principal intracellular targets. Recent molecular studies of endolysosomal Ca2+ physiology and its regulation by NAADP-gated TPCs are providing exciting new insights into the mechanisms of Ca2+-signal initiation that control a wide range of cellular processes and play a role in disease. These developments underscore a new central role for the endolysosomal system in cellular Ca2+ regulation and signalling.
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Masoodi M, Nicolaou A, Gledhill K, Rhodes LE, Tobin DJ, Thody AJ. Prostaglandin D production in FM55 melanoma cells is regulated by alpha-melanocyte-stimulating hormone and is not related to melanin production. Exp Dermatol 2011; 19:751-3. [PMID: 20482620 PMCID: PMC3068286 DOI: 10.1111/j.1600-0625.2010.01098.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study shows that prostaglandins in human FM55 melanoma cells and epidermal melanocytes are produced by COX-1. Prostaglandin production in FM55 melanoma cells was unrelated to that of melanin suggesting that the two processes can occur independently. Alpha-melanocyte-stimulating hormone, which had no effect on melanin production in FM55 cells, stimulated PGD(2) production in these cells without affecting PGE(2). While cAMP pathways may be involved in regulating PGD(2) production, our results suggest that alpha-MSH acts independently of cAMP, possibly by regulating the activity of lipocalin-type PGD synthase. This alpha-MSH-mediated effect may be associated with its role as an immune modulator.
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Acidic calcium stores open for business: expanding the potential for intracellular Ca2+ signaling. Trends Cell Biol 2010; 20:277-86. [PMID: 20303271 DOI: 10.1016/j.tcb.2010.02.003] [Citation(s) in RCA: 209] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 02/08/2010] [Accepted: 02/11/2010] [Indexed: 12/18/2022]
Abstract
Changes in cytosolic calcium concentration are crucial for a variety of cellular processes in all cells. It has long been appreciated that calcium is stored and released from intracellular calcium stores such as the endoplasmic reticulum. However, emerging evidence indicates that calcium is also dynamically regulated by a seemingly disparate collection of acidic organelles. In this paper, we review the defining features of these 'acidic calcium stores' and highlight recent progress in understanding the mechanisms of uptake and release of calcium from these stores. We also examine the nature of calcium buffering within the stores, and summarize the physiological and pathophysiological significance of these ubiquitous organelles in calcium signaling.
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Simon JD, Hong L, Peles DN. Insights into melanosomes and melanin from some interesting spatial and temporal properties. J Phys Chem B 2008; 112:13201-17. [PMID: 18817437 DOI: 10.1021/jp804248h] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Melanosomes are organelles found in a wide variety of tissues throughout the animal kingdom and exhibit a range of different shapes: spheres of up to approximately 1 mum diameters and ellipsoids with lengths of up to approximately 2 mum and varying aspect ratios. The functions of melanosomes include photoprotection, mitigation of the effects of reactive oxygen species, and metal chelation. The melanosome contains a variety of biological molecules, e.g., proteins and lipids, but the dominant constituent is the pigment melanin, and the functions ascribed to melanosomes are uniquely enabled by the chemical properties of the melanins they contain. In the past decade, there has been significant progress in understanding melanins and their impact on human health. While the molecular details of melanin production and how the pigment is organized within the melanosome determine its properties and biological functions, the physical and chemical properties of the surface of the melanosome are central to their range of ascribed functions. Surprisingly, few studies designed to probe this biological surface have been reported. In this article, we discuss recent work using surface-sensitive analytic, spectroscopic, and imaging techniques to examine the structural and chemical properties of many types of natural pigments: sepia melanin granules, human and bovine ocular melanosomes, human hair melanosomes, and neuromelanin. N 2 adsorption/desorption measurements and atomic force microscopy provide novel insights into surface morphology. The chemical properties of the melanins present on the surface are revealed by X-ray photoelectron spectroscopy and photoemission electron microscopy. These technologies are also applied to elucidate changes in surface properties that occur with aging. Specifically, studies of the surface properties of human retinal pigment epithelium melanosomes as a function of age are stimulating the development of models for their age-dependent behaviors. The article concludes with a brief discussion of important unanswered research questions in this field.
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Affiliation(s)
- John D Simon
- Department of Chemistry, Duke UNiversity, Durham, NC, USA
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Analysis of cultured human melanocytes based on polymorphisms within the SLC45A2/MATP, SLC24A5/NCKX5, and OCA2/P loci. J Invest Dermatol 2008; 129:392-405. [PMID: 18650849 DOI: 10.1038/jid.2008.211] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Single nucleotide polymorphisms (SNPs) within the SLC45A2/MATP, SLC24A5/NCKX5, and OCA2/P genes have been associated with natural variation of pigmentation traits in human populations. Here, we describe the characterization of human primary melanocytic cells genotyped for polymorphisms within the MATP, NCKX5, or OCA2 loci. On the basis of genotype, these cultured cells reflect the phenotypes observed by others in terms of both melanin content and tyrosinase (TYR) activity when comparing skin designated as either "White" or "Black". We found a statistically significant association of MATP-374L (darker skin) with higher TYR protein abundance that was not observed for any NCKX5-111 or OCA2 rs12913832 allele. MATP-374L/L homozygous strains displayed significantly lower MATP transcript levels compared to MATP-374F/F homozygous cells, but this did not reach statistical significance based on NCKX5 or OCA2 genotype. Similarly, we observed significantly increased levels of OCA2 mRNA in rs12913832-T (brown eye) homozygotes compared to rs12913832-C (blue eye) homozygous strains, which was not observed for MATP or NCKX5 gene transcripts. In genotype-phenotype associations performed on a collection of 226 southern European individuals using these same SNPs, we were able to show strong correlations in MATP-L374F, OCA2, and melanocortin-1 receptor with skin, eye, and hair color variation, respectively.
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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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Hong L, Simon JD. Current understanding of the binding sites, capacity, affinity, and biological significance of metals in melanin. J Phys Chem B 2007; 111:7938-47. [PMID: 17580858 PMCID: PMC2533804 DOI: 10.1021/jp071439h] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Metal chelation is often invoked as one of the main biological functions of melanin. In order to understand the interaction between metals and melanin, extensive studies have been carried out to determine the nature of the metal binding sites, binding capacity, and affinity. These data are central to efforts aimed at elucidating the role metal binding plays in determining the physical, structural, biological, and photochemical properties of melanin. This article examines the current state of understanding of this field.
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Affiliation(s)
- Lian Hong
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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Bush WD, Simon JD. Quantification of Ca(2+) binding to melanin supports the hypothesis that melanosomes serve a functional role in regulating calcium homeostasis. ACTA ACUST UNITED AC 2007; 20:134-9. [PMID: 17371440 DOI: 10.1111/j.1600-0749.2007.00362.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Calcium regulation in melanocytes affects numerous biological pathways including protecting the redox balance in the cell and regulating the supply of substrate, l-tyrosine, for melanogenesis. The pigment contained in the melanocytes, melanin, has been implicated in maintaining calcium homeostasis in the cell and is known to be involved with calcium ion regulation in the inner ear. Herein, the association constant for Ca(2+) binding to Sepia melanin is determined by isothermal titration calorimetry to be 3.3 (+/-0.2) x 10(3)/M. This value is comparable with other well-established intracellular calcium-binding proteins that serve to buffer calcium concentrations, lending further support to the hypothesis that melanosomes serve as intracellular mediators of calcium homeostasis in melanocytes. Using this binding constant and the data from a fluorescent Ca(2+) displacement assay, the pK(a) of the carboxyl group coordinated to Ca(2+) is determined to be 3.1 +/- 0.1.
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Affiliation(s)
- William D Bush
- Department of Chemistry, Duke University, Durham, NC, USA
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Liu Y, Hong L, Kempf VR, Wakamatsu K, Ito S, Simon JD. Ion-exchange and adsorption of Fe(III) by Sepia melanin. ACTA ACUST UNITED AC 2004; 17:262-9. [PMID: 15140071 DOI: 10.1111/j.1600-0749.2004.00140.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Sepia eumelanin is associated with many metal ions, yet little is known about its metal binding capacity and the chemical nature of the binding site(s). Herein, the natural concentrations of metal ions are presented and the ability to remove metals by exposure of the melanin granules to EDTA is quantified. The results reveal that the binding constants of melanin at pH 5.8 for Mg(II), Ca(II), Sr(II) and Cu(II) are, respectively, 5, 4, 14 and 34 times greater than the corresponding binding constants of these ions with EDTA. By exposing Sepia eumelanin to aqueous solutions of FeCl(3), the content of bound Fe(III) can be increased from a natural concentration of approximately 180 ppm to a saturation limit of approximately 80 000 ppm or 1.43 mmol/g of melanin. Similar saturation limits are found for Mg(II) and Ca(II). Exposure of Sepia melanin granules to aqueous solutions containing Ca(II) results in the stoichiometric replacement of the initially bound Mg(II), arguing that these two ions occupy the same binding site(s) in the pigment. The pH-dependent binding of Mg(II) and Ca(II) suggests coordination of these ions to carboxylic acid groups in the pigment. Mg(II) and Ca(II) can be added to a Fe(III)-saturated melanin sample without affecting the amount of Fe(III) pre-adsorbed, clearly establishing Fe(III) and Mg(II)/Ca(II) occupy different binding sites. Taking recent Raman spectroscopic data into account, the binding of Fe(III) is concluded to involve coordination to o-dihydroxyl groups. The effects of metal ion content on the surface morphology were analyzed. No significant changes were found over the full range of Fe(III) concentration studied, which is supported by the Brunauer-Emmett-Teller surface area analysis. These observations imply the existence of channels within the melanin granules that can serve to transport metal ions.
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Affiliation(s)
- Yan Liu
- Department of Chemistry, Duke University, Durham, NC, USA
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Hoogduijn MJ, Cemeli E, Ross K, Anderson D, Thody AJ, Wood JM. Melanin protects melanocytes and keratinocytes against H2O2-induced DNA strand breaks through its ability to bind Ca2+. Exp Cell Res 2004; 294:60-7. [PMID: 14980501 DOI: 10.1016/j.yexcr.2003.11.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 11/10/2003] [Indexed: 10/26/2022]
Abstract
Reactive oxygen species (ROS) such as hydrogen peroxide (H(2)O(2)) are produced in the skin under the influence of UV radiation. These compounds are highly reactive and can induce DNA lesions in epidermal cells. Melanin is considered to protect human skin against DNA damage by absorbing UV radiation. We have investigated whether melanin can, in addition, offer protection against the effects of H(2)O(2) in human melanocytes and HaCaT keratinocytes. In the present study, it was shown that 40 and 100 microM H(2)O(2) increased the number of DNA strand breaks as measured using the comet assay, in melanocytes of Caucasian origin. In melanocytes of the same origin in which melanin levels were increased by culturing in presence of 10 mM NH(4)Cl and elevated l-tyrosine, H(2)O(2)-induced DNA damage was reduced compared to that in control melanocytes. Similarly, HaCaT cells that were loaded with melanin were better protected against H(2)O(2)-induced DNA strand breaks than control HaCaT cells. These protective effects of melanin were mimicked by the intracellular Ca(2+)-chelator BAPTA. Thus, BAPTA reduced the level of H(2)O(2)-induced DNA strand breaks in melanocytes. Like BAPTA, melanin is known to be a potent chelator of Ca(2+) and this was confirmed in the present study. It was shown that melanin levels in melanocytic cells correlated directly with intracellular Ca(2+) binding capacity and, in addition, correlated inversely with H(2)O(2)-induced increases in intracellular Ca(2+). Our results show that melanin may have an important role in regulating intracellular Ca(2+) homeostasis and it is suggested that melanin protects against H(2)O(2)-induced DNA strand breaks in both melanocytes and keratinocytes and through its ability to bind Ca(2+).
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Affiliation(s)
- M J Hoogduijn
- Department of Biomedical Sciences, University of Bradford, Bradford, UK.
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Affiliation(s)
- Jodie M. Jawor
- Department of Biology, University of Dayton, Dayton, Ohio 45469-2320, USA
| | - Randall Breitwisch
- Department of Biology, University of Dayton, Dayton, Ohio 45469-2320, USA
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