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Ye Sun - One of the best experts on this subject based on the ideXlab platform.
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The Canonical Wnt Signal Restricts the Glycogen Synthase Kinase 3/Fbw7-Dependent Ubiquitination and Degradation of EYA1
2016Co-Authors: Ye SunAbstract:Haploinsufficiency of EYA1 causes the branchio-oto-renal (BOR) syndrome, and abnormally high levels of EYA1 are linked to breast cancer progression and poor prognosis. Therefore, regulation of EYA1 activity is key to its tissue-specific functions and oncogenic activities. Here, we show that EYA1 is posttranslationally modified by ubiquitin and that its ubiquitination level is self-limited to prevent premature degradation. EYA1 has an evolutionarily conserved CDC4 phosphodegron (CPD) signal, a target site of glycogen synthase kinase 3 (GSK3) kinase and Fbw7 ubiquitin ligase, which is required for EYA1 ubiquitination. Genetic deletion of Fbw7 and pharmacological inhibition of GSK3 significantly decrease EYA1 ubiquitination. Conversely, activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and the canonical Wnt signal suppresses EYA1 ubiquitination. Compound EYA1/;Wnt9b/mutants exhibit an increased penetrance of renal defect, indicating that they function in the same genetic pathway in vivo. Together, these findings reveal that the canonical Wnt and PI3K/Akt signal pathways restrain the GSK3/Fbw7-dependent EYA1 ubiquitination, and they further suggest that dysregulation of this novel axis contributes to tumorigenesis. The name of the eyes absent (eya) gene tells only a partial tale.Indeed, it is required for development of and is capable of inducing the ectopic Drosophila eye (1–3). The function of mam-malian Eya family proteins, however, expands beyond organogen-esis (4–6), from tumorigenesis (7–10) to tissue remodeling (11, 12) to innate immunity (13). The underlying mechanism of Eya
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the pi3k akt signal hyperactivates EYA1 via the sumoylation pathway
Oncogene, 2015Co-Authors: Ye Sun, Satoshi KanekoAbstract:Eyes absent 1 (EYA1) is a conserved critical regulator of organ-specific stem cells. Ectopic EYA1 activities, however, promote transformation of mammary epithelial cells. Signals that instigate EYA1 oncogenic activities remain to be determined. Here, we show that Akt1 kinase physically interacts with EYA1 and phosphorylates a conserved consensus site of the Akt kinase. PI3K/Akt signaling enhances EYA1 transcription activity, which largely attributes to the phosphorylation-induced reduction of EYA1 SUMOylation. Indeed, SUMOylation inhibits EYA1 transcription activity; and pharmacologic and genetic activation of PI3K/Akt robustly reduces EYA1 SUMOylation. Wild-type but not Akt phosphorylation site mutant EYA1 variant rescues the cell migratory phenotype of EYA1-silenced breast cancer cells, highlighting the importance of EYA1 phosphorylation. Furthermore, knockdown EYA1 sensitizes breast cancer cells to the PI3K/Akt1 inhibitor and irradiation treatments. Thus, the PI3K/Akt signal pathway activates EYA1. These findings further suggest that regulation of SUMOylation by PI3K/Akt signaling is likely an important aspect of tumorigenesis.
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The PI3K/Akt signal hyperactivates EYA1 via the SUMOylation pathway
Oncogene, 2014Co-Authors: Ye Sun, Satoshi KanekoAbstract:Eyes absent 1 (EYA1) is a conserved critical regulator of organ-specific stem cells. Ectopic EYA1 activities, however, promote transformation of mammary epithelial cells. Signals that instigate EYA1 oncogenic activities remain to be determined. Here, we show that Akt1 kinase physically interacts with EYA1 and phosphorylates a conserved consensus site of the Akt kinase. PI3K/Akt signaling enhances EYA1 transcription activity, which largely attributes to the phosphorylation-induced reduction of EYA1 SUMOylation. Indeed, SUMOylation inhibits EYA1 transcription activity; and pharmacologic and genetic activation of PI3K/Akt robustly reduces EYA1 SUMOylation. Wild-type but not Akt phosphorylation site mutant EYA1 variant rescues the cell migratory phenotype of EYA1-silenced breast cancer cells, highlighting the importance of EYA1 phosphorylation. Furthermore, knockdown EYA1 sensitizes breast cancer cells to the PI3K/Akt1 inhibitor and irradiation treatments. Thus, the PI3K/Akt signal pathway activates EYA1. These findings further suggest that regulation of SUMOylation by PI3K/Akt signaling is likely an important aspect of tumorigenesis.
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The Canonical Wnt Signal Restricts the Glycogen Synthase Kinase 3/Fbw7-Dependent Ubiquitination and Degradation of EYA1 Phosphatase
Molecular and cellular biology, 2014Co-Authors: Ye SunAbstract:Haploinsufficiency of EYA1 causes the branchio-oto-renal (BOR) syndrome, and abnormally high levels of EYA1 are linked to breast cancer progression and poor prognosis. Therefore, regulation of EYA1 activity is key to its tissue-specific functions and oncogenic activities. Here, we show that EYA1 is posttranslationally modified by ubiquitin and that its ubiquitination level is selflimited to prevent premature degradation. EYA1 has an evolutionarily conserved CDC4 phosphodegron (CPD) signal, a target site of glycogen synthase kinase 3 (GSK3) kinase and Fbw7 ubiquitin ligase, which is required for EYA1 ubiquitination. Genetic deletion ofFbw7and pharmacological inhibition of GSK3 significantly decrease EYA1 ubiquitination. Conversely, activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and the canonical Wnt signal suppresses EYA1 ubiquitination. Compound EYA1 / ;Wnt9b / mutants exhibit an increased penetrance of renal defect, indicating that they function in the same genetic pathway in vivo. Together, these findings reveal that the canonical Wnt and PI3K/Akt signal pathways restrain the GSK3/Fbw7dependent EYA1 ubiquitination, and they further suggest that dysregulation of this novel axis contributes to tumorigenesis.
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EYA1 Phosphatase Function Is Essential To Drive Breast Cancer Cell Proliferation Through Cyclin D1
Cancer research, 2013Co-Authors: Shaoxin Cai, Ye Sun, Lifeng Tian, Ke Chen, Jing Wang, Adam ErtelAbstract:The Drosophila Eyes Absent Homologue 1 (EYA1) is a component of the retinal determination gene network and serves as an H2AX phosphatase. The cyclin D1 gene encodes the regulatory subunits of a holoenzyme that phosphorylates and inactivates the pRb protein. Herein, comparison with normal breast showed that EYA1 is overexpressed with cyclin D1 in luminal B breast cancer subtype. EYA1 enhanced breast tumor growth in mice in vivo, requiring the phosphatase domain. EYA1 enhanced cellular proliferation, inhibited apoptosis, and induced contact-independent growth and cyclin D1 abundance. The induction of cellular proliferation and cyclin D1 abundance, but not apoptosis, was dependent upon the EYA1 phosphatase domain. The EYA1-mediated transcriptional induction of cyclin D1 occurred via the AP-1-binding site at -953 and required the EYA1 phosphatase function. The AP-1 mutation did not affect SIX1-dependent activation of cyclin D1. EYA1 was recruited in the context of local chromatin to the cyclin D1 AP-1 site. The EYA1 phosphatase function determined the recruitment of CBP, RNA polymerase II, and acetylation of H3K9 at the cyclin D1 gene AP-1 site regulatory region in the context of local chromatin. The EYA1 phosphatase regulates cell-cycle control via transcriptional complex formation at the cyclin D1 promoter.
Mohi Ahmed - One of the best experts on this subject based on the ideXlab platform.
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the phosphatase transcription activator EYA1 is targeted by anaphase promoting complex cdh1 for degradation at m to g1 transition
Molecular and Cellular Biology, 2013Co-Authors: Jianbo Sun, Elaine Y.m. Wong, Zoi Karoulia, Mohi Ahmed, Keiji ItohAbstract:The phosphatase and transactivator EYA family proteins are overexpressed in many cancer cell lines and are abundantly distributed in undifferentiated cells during development. Loss-of-function studies have shown that EYA1 is required for cell proliferation and survival during mammalian organogenesis. However, how EYA1 is regulated during development is unknown. Here, we report that EYA1 is regulated throughout the cell cycle via ubiquitin-mediated proteolysis. The level of EYA1 protein fluctuates in the cell cycle, peaking during mitosis and dropping drastically as cells exit into G1. We found that EYA1 is efficiently degraded during mitotic exit in a Cdh1-dependent manner and that these two proteins physically interact. Overexpression of Cdh1 reduces the protein levels of ectopically expressed or endogenous EYA1, whereas depletion of Cdh1 by RNA interference stabilizes the EYA1 protein. Together, our results indicate that anaphase-promoting complex/cyclosome (APC/C)–Cdh1 specifically targets EYA1 for degradation during M-to-G1 transition, failure of which may compromise cell proliferation and survival.
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EYA1 six1 complex in neurosensory cell fate induction in the mammalian inner ear
Hearing Research, 2013Co-Authors: Elaine Y.m. Wong, Mohi AhmedAbstract:The phosphatase-transactivator EYA1 interacts with the homeodomain protein SIX1 to form transcriptional activation complexes, which play essential roles in regulating cell proliferation, survival and induction of sensory and neuronal differentiation programs during inner ear development. Mutations of the EYA1 and Six1 genes cause profound developmental auditory defects in mice and humans. The molecular mechanisms and developmental processes controlled by the EYA1 and SIX1 complex in inner ear development and neurosensory fate induction are the focus of this review.
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The phosphatase-transcription activator EYA1 is targeted by anaphase-promoting complex/Cdh1 for degradation at M-to-G1 transition.
Molecular and cellular biology, 2012Co-Authors: Jianbo Sun, Elaine Y.m. Wong, Zoi Karoulia, Mohi Ahmed, Keiji ItohAbstract:The phosphatase and transactivator EYA family proteins are overexpressed in many cancer cell lines and are abundantly distributed in undifferentiated cells during development. Loss-of-function studies have shown that EYA1 is required for cell proliferation and survival during mammalian organogenesis. However, how EYA1 is regulated during development is unknown. Here, we report that EYA1 is regulated throughout the cell cycle via ubiquitin-mediated proteolysis. The level of EYA1 protein fluctuates in the cell cycle, peaking during mitosis and dropping drastically as cells exit into G1. We found that EYA1 is efficiently degraded during mitotic exit in a Cdh1-dependent manner and that these two proteins physically interact. Overexpression of Cdh1 reduces the protein levels of ectopically expressed or endogenous EYA1, whereas depletion of Cdh1 by RNA interference stabilizes the EYA1 protein. Together, our results indicate that anaphase-promoting complex/cyclosome (APC/C)–Cdh1 specifically targets EYA1 for degradation during M-to-G1 transition, failure of which may compromise cell proliferation and survival.
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EYA1–SIX1 complex in neurosensory cell fate induction in the mammalian inner ear
Hearing research, 2012Co-Authors: Elaine Y.m. Wong, Mohi AhmedAbstract:The phosphatase-transactivator EYA1 interacts with the homeodomain protein SIX1 to form transcriptional activation complexes, which play essential roles in regulating cell proliferation, survival and induction of sensory and neuronal differentiation programs during inner ear development. Mutations of the EYA1 and Six1 genes cause profound developmental auditory defects in mice and humans. The molecular mechanisms and developmental processes controlled by the EYA1 and SIX1 complex in inner ear development and neurosensory fate induction are the focus of this review.
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EYA1 and six1 drive the neuronal developmental program in cooperation with the swi snf chromatin remodeling complex and sox2 in the mammalian inner ear
Development, 2012Co-Authors: Mohi AhmedAbstract:Inner ear neurogenesis depends upon the function of the proneural basic helix-loop-helix (bHLH) transcription factors NEUROG1 and NEUROD1. However, the transcriptional regulation of these factors is unknown. Here, using loss- and gain-of-function models, we show that EYA1 and SIX1 are crucial otic neuronal determination factors upstream of NEUROG1 and NEUROD1. Overexpression of both EYA1 and Six1 is sufficient to convert non-neuronal epithelial cells within the otocyst and cochlea as well as the 3T3 fibroblast cells into neurons. Strikingly, all the ectopic neurons express not only Neurog1 and Neurod1 but also mature neuronal markers such as neurofilament, indicating that EYA1 and Six1 function upstream of, and in the same pathway as, Neurog1 and Neurod1 to not only induce neuronal fate but also regulate their differentiation. We demonstrate that EYA1 and SIX1 interact directly with the SWI/SNF chromatin-remodeling subunits BRG1 and BAF170 to drive neurogenesis cooperatively in 3T3 cells and cochlear nonsensory epithelial cells, and that SOX2 cooperates with these factors to mediate neuronal differentiation. Importantly, we show that the ATPase BRG1 activity is required for not only EYA1- and SIX1-induced ectopic neurogenesis but also normal neurogenesis in the otocyst. These findings indicate that EYA1 and SIX1 are key transcription factors in initiating the neuronal developmental program, probably by recruiting and interacting with the SWI/SNF chromatin-remodeling complex to specifically mediate Neurog1 and Neurod1 transcription.
Satoshi Kaneko - One of the best experts on this subject based on the ideXlab platform.
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the pi3k akt signal hyperactivates EYA1 via the sumoylation pathway
Oncogene, 2015Co-Authors: Ye Sun, Satoshi KanekoAbstract:Eyes absent 1 (EYA1) is a conserved critical regulator of organ-specific stem cells. Ectopic EYA1 activities, however, promote transformation of mammary epithelial cells. Signals that instigate EYA1 oncogenic activities remain to be determined. Here, we show that Akt1 kinase physically interacts with EYA1 and phosphorylates a conserved consensus site of the Akt kinase. PI3K/Akt signaling enhances EYA1 transcription activity, which largely attributes to the phosphorylation-induced reduction of EYA1 SUMOylation. Indeed, SUMOylation inhibits EYA1 transcription activity; and pharmacologic and genetic activation of PI3K/Akt robustly reduces EYA1 SUMOylation. Wild-type but not Akt phosphorylation site mutant EYA1 variant rescues the cell migratory phenotype of EYA1-silenced breast cancer cells, highlighting the importance of EYA1 phosphorylation. Furthermore, knockdown EYA1 sensitizes breast cancer cells to the PI3K/Akt1 inhibitor and irradiation treatments. Thus, the PI3K/Akt signal pathway activates EYA1. These findings further suggest that regulation of SUMOylation by PI3K/Akt signaling is likely an important aspect of tumorigenesis.
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The PI3K/Akt signal hyperactivates EYA1 via the SUMOylation pathway
Oncogene, 2014Co-Authors: Ye Sun, Satoshi KanekoAbstract:Eyes absent 1 (EYA1) is a conserved critical regulator of organ-specific stem cells. Ectopic EYA1 activities, however, promote transformation of mammary epithelial cells. Signals that instigate EYA1 oncogenic activities remain to be determined. Here, we show that Akt1 kinase physically interacts with EYA1 and phosphorylates a conserved consensus site of the Akt kinase. PI3K/Akt signaling enhances EYA1 transcription activity, which largely attributes to the phosphorylation-induced reduction of EYA1 SUMOylation. Indeed, SUMOylation inhibits EYA1 transcription activity; and pharmacologic and genetic activation of PI3K/Akt robustly reduces EYA1 SUMOylation. Wild-type but not Akt phosphorylation site mutant EYA1 variant rescues the cell migratory phenotype of EYA1-silenced breast cancer cells, highlighting the importance of EYA1 phosphorylation. Furthermore, knockdown EYA1 sensitizes breast cancer cells to the PI3K/Akt1 inhibitor and irradiation treatments. Thus, the PI3K/Akt signal pathway activates EYA1. These findings further suggest that regulation of SUMOylation by PI3K/Akt signaling is likely an important aspect of tumorigenesis.
Pinxian Xu - One of the best experts on this subject based on the ideXlab platform.
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the EYA1 phosphatase mediates shh driven symmetric cell division of cerebellar granule cell precursors
bioRxiv, 2019Co-Authors: Daniel Merk, Samuel M Cohen, Grace H Hwang, Kristina Rehm, Maria F Pazyramurphy, Pengcheng Zhou, Xuesong Zhao, Jose Alfaro, Eun Young Park, Pinxian XuAbstract:Abstract During neural development, stem and precursor cells can divide either symmetrically or asymmetrically. The transition between symmetric and asymmetric cell divisions is a major determinant of precursor cell expansion and neural differentiation, but the underlying mechanisms that regulate this transition are not well understood. Here, we identify the Sonic hedgehog (Shh) pathway as a critical determinant regulating the mode of division of cerebellar granule cell precursors (GCPs). Using partial gain and loss of function mutations within the Shh pathway, we show that pathway activation determines spindle orientation of GCPs, and that mitotic spindle orientation directly correlates with the mode of division. Mechanistically, we show that the phosphatase EYA1 is essential for implementing Shh-dependent GCP spindle orientation. We identify atypical protein kinase C (aPKC) as a direct target of EYA1 activity and show that EYA1 dephosphorylates Threonine (T410) in the activation loop of this polarity complex component. Thus, EYA1 inactivates the cell polarity complex, resulting in reduced phosphorylation of Numb and other components that regulate the mode of division. This EYA1-dependent cascade is critical in linking spindle orientation, cell cycle exit and terminal differentiation. Together these findings demonstrate that a Shh-EYA1 regulatory axis selectively promotes symmetric cell divisions during cerebellar development by coordinating spindle orientation and cell fate determinants. Summary statement Biological responses to Shh signaling are specified by the magnitude of pathway activation and the cellular context. This study shows that potent Shh signaling regulates mitotic orientation and symmetric division of cerebellar granule cell precursors in a process that requires the phosphatase EYA1 and unequal distribution of cell fate determinants to daughter cells.
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EYA1 regulates the growth of otic epithelium and interacts with pax2 during the development of all sensory areas in the inner ear
Developmental Biology, 2006Co-Authors: Derek Silvius, Sandra Rodrigoblomqvist, Sven Enerback, Pinxian XuAbstract:Members of the Eyes absent (Eya) gene family are important for auditory system development. While mutations in human EYA4 cause late-onset deafness at the DFNA10 locus, mutations in human EYA1 cause branchio–oto–renal (BOR) syndrome. Inactivation of EYA1 in mice causes an early arrest of the inner ear development at the otocyst stage. To better understand the role of EYA1 in inner ear development, we analyzed the cellular and molecular basis of the early defect observed in the EYA1 mutant embryos. We report here that EYA1−/− otic epithelium shows reduced cell proliferation from E8.5 and increased cell apoptosis from E9.0, thus providing insights into the cellular basis of inner ear defect which occurred in the absence of EYA1. Previous studies have suggested that Pax, Eya and Six genes function in a parallel or independent pathway during inner ear development. However, it remains unknown whether Pax genes interact with EYA1 or Six1 during inner ear morphogenesis. To further evaluate whether Pax genes function in the EYA1–Six1 pathway or whether they interact with EYA1 or Six1 during inner ear morphogenesis, we have analyzed the expression pattern of EYA1, Pax2 and Pax8 on adjacent sections of otic epithelium from E8.5 to 9.5 by in situ hybridization and the inner ear gross structures of Pax2, EYA1 and Six1 compound mutants at E17.5 by latex paintfilling. Our data strongly suggest that Pax2 interacts with EYA1 during inner ear morphogenesis, and this interaction is critical for the development of all sensory areas in the inner ear. Furthermore, otic marker analysis in both EYA1−/− and Pax2−/− embryos indicates that EYA1 but not Pax2 regulates the establishment of regional specification of the otic vesicle. Together, these results show that, while EYA1 exerts an early function essential for normal growth and patterning of the otic epithelium, it also functionally synergizes with Pax2 during the morphogenesis of all sensory areas of mammalian inner ear.
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EYA1 is required for the morphogenesis of mammalian thymus, parathyroid and thyroid.
Development, 2002Co-Authors: Pinxian Xu, Heiko Peters, Weiming Zheng, Christine Laclef, Richard L. Maas, Pascal Maire, Xin XuAbstract:Eyes absent ( Eya ) genes regulate organogenesis in both vertebrates and invertebrates. Mutations in human EYA1 cause congenital Branchio-Oto-Renal (BOR) syndrome, while targeted inactivation of murine EYA1 impairs early developmental processes in multiple organs, including ear, kidney and skeletal system. We have now examined the role of EYA1 during the morphogenesis of organs derived from the pharyngeal region, including thymus, parathyroid and thyroid. The thymus and parathyroid are derived from 3rd pharyngeal pouches and their development is initiated via inductive interactions between neural crest-derived arch mesenchyme, pouch endoderm, and possibly the surface ectoderm of 3rd pharyngeal clefts. EYA1 is expressed in all three cell types during thymus and parathyroid development from E9.5 and the organ primordia for both of these structures failed to form in EYA1 –/– embryos. These results indicate that EYA1 is required for the initiation of thymus and parathyroid gland formation. EYA1 is also expressed in the 4th pharyngeal region and ultimobranchial bodies. EYA1 –/– mice show thyroid hypoplasia, with severe reduction in the number of parafollicular cells and the size of the thyroid lobes and lack of fusion between the ultimobranchial bodies and the thyroid lobe. These data indicate that EYA1 also regulates mature thyroid gland formation. Furthermore, we show that Six1 expression is markedly reduced in the arch mesenchyme, pouch endoderm and surface ectoderm in the pharyngeal region of EYA1 –/– embryos, indicating that Six1 expression in those structures is EYA1 dependent. In addition, we show that in EYA1 –/– embryos, the expression of Gcm2 in the 3rd pouch endoderm is undetectable at E10.5, however, the expression of Hox and Pax genes in the pouch endoderm is preserved at E9.5-10.5. Finally, we found that the surface ectoderm of the 3rd and 4th pharyngeal region show increased cell death at E10.5 in EYA1 –/– embryos. Our results indicate that EYA1 controls critical early inductive events involved in the morphogenesis of thymus, parathyroid and thyroid.
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mouse eya genes are expressed during limb tendon development and encode a transcriptional activation function
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Pinxian Xu, Jane Cheng, Jonathan A Epstein, Richard L. MaasAbstract:Vertebrate limb tendons are derived from connective cells of the lateral plate mesoderm. Some of the developmental steps leading to the formation of vertebrate limb tendons have been previously identified; however, the molecular mechanisms responsible for tendinous patterning and maintenance during embryogenesis are largely unknown. The eyes absent (eya) gene of Drosophila encodes a novel nuclear protein of unknown molecular function. Here we show that EYA1 and Eya2, two mouse homologues of Drosophila eya, are expressed initially during limb development in connective tissue precursor cells. Later in limb development, EYA1 and Eya2 expression is associated with cell condensations that form different sets of limb tendons. EYA1 expression is largely restricted to flexor tendons, while Eya2 is expressed in the extensor tendons and ligaments of the phalangeal elements of the limb. These data suggest that Eya genes participate in the patterning of the distal tendons of the limb. To investigate the molecular functions of the Eya gene products, we have analyzed whether the highly divergent PST (proline-serine-threonine)-rich N-terminal regions of EYA1–3 function as transactivation domains. Our results demonstrate that Eya gene products can act as transcriptional activators, and they support a role for this molecular function in connective tissue patterning.
David Warburton - One of the best experts on this subject based on the ideXlab platform.
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abrogation of EYA1 six1 disrupts the saccular phase of lung morphogenesis and causes remodeling
Developmental Biology, 2013Co-Authors: Raghava Reddy, David Warburton, Ahmed H K Elhashash, Mohamed BerikaAbstract:The EYA1 gene encodes a transcriptional co-activator that acts with Six1 to control the development of different organs. However, Six1-EYA1 interactions and functional roles in mesenchymal cell proliferation and differentiation as well as alveolarization during the saccular stage of lung development are still unknown. Herein, we provide the first evidence that Six1 and EYA1 act together to regulate mesenchymal development as well as alveolarization during the saccular phase of lung morphogenesis. Deletion of either or both Six1 and EYA1 genes results in a severe saccular phenotype, including defects of mesenchymal cell development and remodeling of the distal lung septae and arteries. Mutant lung histology at the saccular phase shows mesenchymal and saccular wall thickening, and abnormal proliferation of α-smooth muscle actin-positive cells, as well as increased mesenchymal/fibroblast cell differentiation, which become more sever when deleting both genes. Our study indicates that SHH but not TGF-β signaling pathway is a central mediator for the histologic alterations described in the saccular phenotype of EYA1(-/-) or Six1(-/-) lungs. Indeed, genetic reduction of SHH activity in vivo or inhibition of its activity in vitro substantially rescues lung mesenchymal and alveolar phenotype of mutant mice at the saccular phase. These findings uncover novel functions for Six1-EYA1-SHH pathway during the saccular phase of lung morphogenesis, providing a conceptual framework for future mechanistic and translational studies in this area.
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Abrogation of EYA1/Six1 disrupts the saccular phase of lung morphogenesis and causes remodeling.
Developmental biology, 2013Co-Authors: Raghava Reddy, Mohamed Berika, David Warburton, Ahmed H.k. El-hashashAbstract:The EYA1 gene encodes a transcriptional co-activator that acts with Six1 to control the development of different organs. However, Six1-EYA1 interactions and functional roles in mesenchymal cell proliferation and differentiation as well as alveolarization during the saccular stage of lung development are still unknown. Herein, we provide the first evidence that Six1 and EYA1 act together to regulate mesenchymal development as well as alveolarization during the saccular phase of lung morphogenesis. Deletion of either or both Six1 and EYA1 genes results in a severe saccular phenotype, including defects of mesenchymal cell development and remodeling of the distal lung septae and arteries. Mutant lung histology at the saccular phase shows mesenchymal and saccular wall thickening, and abnormal proliferation of α-smooth muscle actin-positive cells, as well as increased mesenchymal/fibroblast cell differentiation, which become more sever when deleting both genes. Our study indicates that SHH but not TGF-β signaling pathway is a central mediator for the histologic alterations described in the saccular phenotype of EYA1(-/-) or Six1(-/-) lungs. Indeed, genetic reduction of SHH activity in vivo or inhibition of its activity in vitro substantially rescues lung mesenchymal and alveolar phenotype of mutant mice at the saccular phase. These findings uncover novel functions for Six1-EYA1-SHH pathway during the saccular phase of lung morphogenesis, providing a conceptual framework for future mechanistic and translational studies in this area.
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EYA1 protein phosphatase regulates tight junction formation in lung distal epithelium
Journal of Cell Science, 2012Co-Authors: Gianluca Turcatel, Denise Al Alam, David Warburton, Ahmed H K Elhashash, Saaket Varma, Mohamed BerikaAbstract:Little is known about the regulatory mechanisms underlying lung epithelial tight junction (TJ) assembly, which is inextricably linked to the preservation of epithelial polarity, and is highly coordinated by proteins that regulate epithelial cell polarity, such as aPKCζ. We recently reported that EYA1 phosphatase functions through aPKCζ–Notch1 signaling to control cell polarity in the lung epithelium. Here, we have extended these observations to TJ formation to demonstrate that EYA1 is crucial for the maintenance of TJ protein assembly in the lung epithelium, probably by controlling aPKCζ phosphorylation levels, aPKCζ-mediated TJ protein phosphorylation and Notch1–Cdc42 activity. Thus, TJs are disassembled after interfering with EYA1 function in vivo or during calcium-induced TJ assembly in vitro. These effects are reversed by reintroduction of wild-type EYA1 or partially inhibiting aPKCζ in EYA1siRNA cells. Moreover, genetic activation of Notch1 rescues EYA1−/− lung epithelial TJ defects. These findings uncover novel functions for the EYA1–aPKCζ–Notch1–Cdc42 pathway as a crucial regulatory mechanism of TJ assembly and polarity of the lung epithelium, providing a conceptual framework for future mechanistic and translational studies in this area.
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EYA1 controls cell polarity, spindle orientation, cell fate and Notch signaling in distal embryonic lung epithelium
Development (Cambridge England), 2011Co-Authors: Ahmed H.k. El-hashash, Gianluca Turcatel, Denise Al Alam, Sue Buckley, Hiroshi Tokumitsu, Saverio Bellusci, David WarburtonAbstract:Cell polarity, mitotic spindle orientation and asymmetric division play a crucial role in the self-renewal/differentiation of epithelial cells, yet little is known about these processes and the molecular programs that control them in embryonic lung distal epithelium. Herein, we provide the first evidence that embryonic lung distal epithelium is polarized with characteristic perpendicular cell divisions. Consistent with these findings, spindle orientation-regulatory proteins Insc, LGN (Gpsm2) and NuMA, and the cell fate determinant Numb are asymmetrically localized in embryonic lung distal epithelium. Interfering with the function of these proteins in vitro randomizes spindle orientation and changes cell fate. We further show that EYA1 protein regulates cell polarity, spindle orientation and the localization of Numb, which inhibits Notch signaling. Hence, EYA1 promotes both perpendicular division as well as Numb asymmetric segregation to one daughter in mitotic distal lung epithelium, probably by controlling aPKCζ phosphorylation. Thus, epithelial cell polarity and mitotic spindle orientation are defective after interfering with EYA1 function in vivo or in vitro. In addition, in EYA1−/− lungs, perpendicular division is not maintained and Numb is segregated to both daughter cells in mitotic epithelial cells, leading to inactivation of Notch signaling. As Notch signaling promotes progenitor cell identity at the expense of differentiated cell phenotypes, we test whether genetic activation of Notch could rescue the EYA1−/− lung phenotype, which is characterized by loss of epithelial progenitors, increased epithelial differentiation but reduced branching. Indeed, genetic activation of Notch partially rescues EYA1−/− lung epithelial defects. These findings uncover novel functions for EYA1 as a crucial regulator of the complex behavior of distal embryonic lung epithelium.
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Eyes absent 1 (EYA1) is a critical coordinator of epithelial, mesenchymal and vascular morphogenesis in the mammalian lung
Developmental biology, 2010Co-Authors: Ahmed H.k. El-hashash, Gianluca Turcatel, Denise Al Alam, Saverio Bellusci, David WarburtonAbstract:The proper level of proliferation and differentiation along the proximodistal axis is crucial for lung organogenesis. Elucidation of the factors that control these processes will therefore provide important insights into embryonic lung development and regeneration. EYA1 is a transcription factor/protein phosphatase that regulates cell lineage specification and proliferation. Yet its functions during lung development are unknown. In this paper we show that EYA1-/- lungs are severely hypoplastic with reduced epithelial branching and increased mesenchymal cellularity. EYA1 is expressed at the distal epithelial tips of branching tubules as well as in the surrounding distal mesenchyme. EYA1-/- lung epithelial cells show loss of progenitor cell markers with increased expression of differentiation markers and cell cycle exit. In addition, EYA1–/– embryos and newborn mice exhibit severe defects in the smooth muscle component of the bronchi and major pulmonary vessels with decreased Fgf10 expression. These defects lead to rupture of the major vessels and hemorrhage into the lungs after birth. Treatment of EYA1-/- epithelial explants in culture with recombinant Fgf10 stimulates epithelial branching. Since Shh expression and activity are abnormally increased in EYA1-/- lungs, we tested whether genetically lowering Shh activity could rescue the EYA1-/- lung phenotype. Indeed, genetic reduction of Shh partially rescues EYA1-/- lung defects while restoring Fgf10 expression. This study provides the first evidence that EYA1 regulates Shh signaling in embryonic lung, thus ensuring the proper level of proliferation and differentiation along the proximodistal axis of epithelial, mesenchymal and endothelial cells. These findings uncover novel functions for EYA1 as a critical upstream coordinator of Shh-Fgf10 signaling during embryonic lung development. We conclude, therefore, that EYA1 function is critical for proper coordination of lung epithelial, mesenchymal and vascular development.
