51
|
Miura GI, Roignant JY, Wassef M, Treisman JE. Myopic acts in the endocytic pathway to enhance signaling by the Drosophila EGF receptor. Development 2008; 135:1913-22. [PMID: 18434417 DOI: 10.1242/dev.017202] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Endocytosis of activated receptors can control signaling levels by exposing the receptors to novel downstream molecules or by instigating their degradation. Epidermal growth factor receptor (EGFR) signaling has crucial roles in development and is misregulated in many cancers. We report here that Myopic, the Drosophila homolog of the Bro1-domain tyrosine phosphatase HD-PTP, promotes EGFR signaling in vivo and in cultured cells. myopic is not required in the presence of activated Ras or in the absence of the ubiquitin ligase Cbl, indicating that it acts on internalized EGFR, and its overexpression enhances the activity of an activated form of EGFR. Myopic is localized to intracellular vesicles adjacent to Rab5-containing early endosomes, and its absence results in the enlargement of endosomal compartments. Loss of Myopic prevents cleavage of the EGFR cytoplasmic domain, a process controlled by the endocytic regulators Cbl and Sprouty. We suggest that Myopic promotes EGFR signaling by mediating its progression through the endocytic pathway.
Collapse
Affiliation(s)
- Grant I Miura
- Kimmel Center for Biology and Medicine of the Skirball Institute, NYU School of Medicine, Department of Cell Biology, 540 First Avenue, New York, NY 10016, USA
| | | | | | | |
Collapse
|
52
|
Newman SA, Bhat R. Dynamical patterning modules: physico-genetic determinants of morphological development and evolution. Phys Biol 2008; 5:015008. [PMID: 18403826 DOI: 10.1088/1478-3975/5/1/015008] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The shapes and forms of multicellular organisms arise by the generation of new cell states and types and changes in the numbers and rearrangements of the various kinds of cells. While morphogenesis and pattern formation in all animal species are widely recognized to be mediated by the gene products of an evolutionarily conserved 'developmental-genetic toolkit', the link between these molecular players and the physics underlying these processes has been generally ignored. This paper introduces the concept of 'dynamical patterning modules' (DPMs), units consisting of one or more products of the 'toolkit' genes that mobilize physical processes characteristic of chemically and mechanically excitable meso- to macroscopic systems such as cell aggregates: cohesion, viscoelasticity, diffusion, spatiotemporal heterogeneity based on lateral inhibition and multistable and oscillatory dynamics. We suggest that ancient toolkit gene products, most predating the emergence of multicellularity, assumed novel morphogenetic functions due to change in the scale and context inherent to multicellularity. We show that DPMs, acting individually and in concert with each other, constitute a 'pattern language' capable of generating all metazoan body plans and organ forms. The physical dimension of developmental causation implies that multicellular forms during the explosive radiation of animal body plans in the middle Cambrian, approximately 530 million years ago, could have explored an extensive morphospace without concomitant genotypic change or selection for adaptation. The morphologically plastic body plans and organ forms generated by DPMs, and their ontogenetic trajectories, would subsequently have been stabilized and consolidated by natural selection and genetic drift. This perspective also solves the apparent 'molecular homology-analogy paradox', whereby widely divergent modern animal types utilize the same molecular toolkit during development by proposing, in contrast to the Neo-Darwinian principle, that phenotypic disparity early in evolution occurred in advance of, rather than closely tracked, genotypic change.
Collapse
Affiliation(s)
- Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA.
| | | |
Collapse
|
53
|
Huang X, Litingtung Y, Chiang C. Region-specific requirement for cholesterol modification of sonic hedgehog in patterning the telencephalon and spinal cord. Development 2008; 134:2095-105. [PMID: 17507410 DOI: 10.1242/dev.000729] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sonic hedgehog (Shh) secreted from the axial signaling centers of the notochord and prechordal plate functions as a morphogen in dorsoventral patterning of the neural tube. Active Shh is uniquely cholesterol-modified and the hydrophobic nature of cholesterol suggests that it might regulate Shh spreading in the neural tube. Here, we examined the capacity of Shh lacking the cholesterol moiety (ShhN) to pattern different cell types in the telencephalon and spinal cord. In mice expressing ShhN, we detected low-level ShhN in the prechordal plate and notochord, consistent with the notion that ShhN can rapidly spread from its site of synthesis. Surprisingly, we found that low-level ShhN can elicit the generation of a full spectrum of ventral cell types in the spinal cord, whereas ventral neuronal specification and ganglionic eminence development in the Shh(N/-) telencephalon were severely impaired, suggesting that telencephalic patterning is more sensitive to alterations in local Shh concentration and spreading. In agreement, we observed induction of Shh pathway activity and expression of ventral markers at ectopic sites in the dorsal telencephalon indicative of long-range ShhN activity. Our findings indicate an essential role for the cholesterol moiety in restricting Shh dilution and deregulated spread for patterning the telencephalon. We propose that the differential effect of ShhN in patterning the spinal cord versus telencephalon may be attributed to regional differences in the maintenance of Shh expression in the ventral neuroepithelium and differences in dorsal tissue responsiveness to deregulated Shh spreading behavior.
Collapse
Affiliation(s)
- Xi Huang
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | | | | |
Collapse
|
54
|
TGFbeta-SMAD signal transduction: molecular specificity and functional flexibility. Nat Rev Mol Cell Biol 2007; 8:970-82. [PMID: 18000526 DOI: 10.1038/nrm2297] [Citation(s) in RCA: 954] [Impact Index Per Article: 56.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ligands of the transforming growth factor-beta (TGFbeta) superfamily of growth factors initiate signal transduction through a bewildering complexity of ligand-receptor interactions. Signalling then converges to nuclear accumulation of transcriptionally active SMAD complexes and gives rise to a plethora of specific functional responses in both embryos and adult organisms. Current research is focused on the mechanisms that regulate SMAD activity to evoke cell-type-specific and context-dependent transcriptional programmes. An equally important challenge is understanding the functional role of signal strength and duration. How are these quantitative aspects of the extracellular signal regulated? How are they then sensed and interpreted, and how do they affect responses?
Collapse
|
55
|
Page KM, Monk NAM, Maini PK. Speed of reaction diffusion in embryogenesis. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:011902. [PMID: 17677489 DOI: 10.1103/physreve.76.011902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Indexed: 05/16/2023]
Abstract
Reaction diffusion systems have been proposed as mechanisms for patterning during many stages of embryonic development. While much attention has been focused on the study of the steady state patterns formed and the robustness of pattern selection, much less is known about the time scales required for pattern formation. Studies of gradient formation by the diffusion of a single morphogen from a localized source have shown that patterning can occur on realistic time scales over distances of a millimeter or less. Reaction diffusion has the potential to give rise to patterns on a faster time scale, since all points in the domain can act as sources of morphogen. However, the speed at which patterning can occur has hitherto not been explored in depth. In this paper, we investigate this issue in specific reaction diffusion models and address the question of whether patterning via reaction diffusion is fast enough to be applicable to morphogenesis.
Collapse
Affiliation(s)
- Karen M Page
- Department of Mathematics, University College London, Gower Street, London WC1E 6BT, United Kingdom.
| | | | | |
Collapse
|
56
|
Simeoni I, Gurdon JB. Interpretation of BMP signaling in early Xenopus development. Dev Biol 2007; 308:82-92. [PMID: 17560972 DOI: 10.1016/j.ydbio.2007.05.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Revised: 05/04/2007] [Accepted: 05/09/2007] [Indexed: 11/18/2022]
Abstract
Very little is known about how the extracellular binding of a morphogen is transduced to the nucleus of a cell in a concentration-related way, enabling cells to interpret their position in a concentration gradient. Here, we have analyzed when and how Xenopus embryo cells perceive and interpret a BMP signal. Dissociated embryo cells are exposed for short times to different concentrations of BMP4. We find that cells are already competent to receive a BMP4 signal at the blastula stage. They phosphorylate Smad1 very rapidly and express downstream genes less than half an hour after exposure to BMP. However, Smad1 is present in the nucleus even in the absence of BMP. To quantitate intracellular signaling after BMP exposure, we have constructed a chimeric type I receptor that registers BMP signaling as the intranuclear migration of Smad2, and as the transcription of Smad2 downstream genes. The combination of the chimeric receptor and GFP-Smad2 makes it possible to follow the transduction of BMP signaling to the nucleus. From our results, we conclude that an extracellular BMP concentration is interpreted by the steady state nuclear concentration of phosphorylated Smad1.
Collapse
Affiliation(s)
- I Simeoni
- Wellcome Trust/Cancer Research UK, Gurdon Institute of Cancer and Development Biology, CB2 1QN Cambridge, UK
| | | |
Collapse
|
57
|
Saka Y, Smith JC. A mechanism for the sharp transition of morphogen gradient interpretation in Xenopus. BMC DEVELOPMENTAL BIOLOGY 2007; 7:47. [PMID: 17506890 PMCID: PMC1885807 DOI: 10.1186/1471-213x-7-47] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 05/16/2007] [Indexed: 12/13/2022]
Abstract
Background One way in which positional information is established during embryonic development is through the graded distribution of diffusible morphogens. Unfortunately, little is known about how cells interpret different concentrations of morphogen to activate different genes or how thresholds are generated in a morphogen gradient. Results Here we show that the concentration-dependent induction of the T-box transcription factor Brachyury (Xbra) and the homeobox-containing gene Goosecoid (Gsc) by activin in Xenopus can be explained by the dynamics of a simple network consisting of three elements with a mutual negative feedback motif that can function to convert a graded signal (activin) into a binary output (Xbra on and Gsc off, or vice versa). Importantly, such a system can display sharp thresholds. Consistent with the predictions of our model, Xenopus ectodermal cells display a binary response at the single cell level after treatment with activin. Conclusion This kind of simple network with mutual negative feedback might provide a general mechanism for selective gene activation in response to different levels of a single external signal. It provides a mechanism by which a sharp boundary might be created between domains of different cell types in response to a morphogen gradient.
Collapse
Affiliation(s)
- Yasushi Saka
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
- Interdisciplinary Research Institute, Institut de Biologie de Lille, 1 rue du Professeur Calmette, BP447, 59021 Lille Cedex, France
| | - James C Smith
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| |
Collapse
|
58
|
Kinoshita T, Jullien J, Gurdon JB. Two-dimensional morphogen gradient in Xenopus: boundary formation and real-time transduction response. Dev Dyn 2007; 235:3189-98. [PMID: 17029288 DOI: 10.1002/dvdy.20963] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Morphogen gradients play an important role in pattern formation in embryo. However, the interpretation of position in a morphogen gradient is not well understood. Because it is hard to analyze morphogen gradients especially in opaque embryos such as those of Xenopus, it is necessary to fix and section the embryo, thereby eliminating the possibility of real-time observation, and making more difficult the interpretation of events that take place in three dimensions. We describe here a two-dimensional preparation of cells from a Xenopus blastula animal cap, in which an activin concentration gradient appears to be formed and interpreted at the same rate and in the same way as in normal embryos. We use two-dimensional preparations of this kind to contribute the following new information about gradient formation and interpretation in embryo. We determine the dynamics of formation of an activin activity gradient in real time. We demonstrate that this gradient is established by diffusion of activin through intercellular space and does not require internalization of receptor or ligand. We also show that the generation of a boundary of gene expression depends on the interpretation, rather than a change of composition, of the concentration gradient.
Collapse
Affiliation(s)
- T Kinoshita
- Developmental Biology, Faculty of Science and Technology, Kwansei Gakuin University, Sanda, Japan.
| | | | | |
Collapse
|
59
|
Itoh S, ten Dijke P. Negative regulation of TGF-beta receptor/Smad signal transduction. Curr Opin Cell Biol 2007; 19:176-84. [PMID: 17317136 DOI: 10.1016/j.ceb.2007.02.015] [Citation(s) in RCA: 296] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 02/09/2007] [Indexed: 12/27/2022]
Abstract
Members of the transforming growth factor-beta (TGF-beta) family are highly conserved multifunctional cell-cell signaling proteins that are of key importance for controlling embryogenesis and tissue homeostasis. At first glance, signaling through TGF-beta family members appears to be a simple process: ligands bind to specific serine/threonine kinase transmembrane receptors, which activate intracellular Smad effector proteins, which in turn relay the signal to the nucleus to control gene transcription. However, recent research has revealed that additional layers of complexity exist at each step in the TGF-beta/Smad pathway. The expression, activation and inactivation, subcellular localization, and stability of TGF-beta signaling components are tightly regulated and subject to input from other signaling pathways. A broad array of Smad interacting partners and diverse post-translational modifications of Smads have been identified. Recently, important advances have been made in our understanding of how TGF-beta family signals are attenuated and terminated to maintain control over this versatile pathway.
Collapse
Affiliation(s)
- Susumu Itoh
- Department of Experimental Pathology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | | |
Collapse
|
60
|
Geldner N, Jürgens G. Endocytosis in signalling and development. CURRENT OPINION IN PLANT BIOLOGY 2006; 9:589-94. [PMID: 17011816 DOI: 10.1016/j.pbi.2006.09.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Accepted: 09/19/2006] [Indexed: 05/08/2023]
Abstract
After a long period of neglect, endocytosis in plants is finally coming of age. The constitutive recycling of plasma membrane proteins has been well established in the past few years, and recent studies report the ligand-induced endocytosis of receptors and other plasma membrane proteins. Signalling by ligand-bound receptors from endosomes has not, however, been demonstrated in plants. Although novel markers have been used to map endocytic pathways, the functional compartmentalisation of endosomes is still controversial. It is thus not clear where and how cargo proteins such as receptors are sorted towards either recycling to the plasma membrane or targeting to the vacuole for degradation.
Collapse
Affiliation(s)
- Niko Geldner
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA.
| | | |
Collapse
|
61
|
Bökel C, Schwabedissen A, Entchev E, Renaud O, González-Gaitán M. Sara endosomes and the maintenance of Dpp signaling levels across mitosis. Science 2006; 314:1135-9. [PMID: 17110576 DOI: 10.1126/science.1132524] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During development, cells acquire positional information by reading the concentration of morphogens. In the developing fly wing, a gradient of the transforming growth factor-beta (TGF-beta)-type morphogen decapentaplegic (Dpp) is transduced into a gradient of concentration of the phosphorylated form of the R-Smad transcription factor Mad. The endosomal protein Sara (Smad anchor for receptor activation) recruits R-Smads for phosphorylation by the type I TGF-beta receptor. We found that Sara, Dpp, and its type I receptor Thickveins were targeted to a subpopulation of apical endosomes in the developing wing epithelial cells. During mitosis, the Sara endosomes and the receptors therein associated with the spindle machinery to segregate into the two daughter cells. Daughter cells thereby inherited equal amounts of signaling molecules and thus retained the Dpp signaling levels of the mother cell.
Collapse
Affiliation(s)
- Christian Bökel
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | | | | | | | | |
Collapse
|
62
|
Abstract
This is a personal historical account of events leading from the earliest success in vertebrate nuclear transfer to the current hope that nuclear reprogramming may facilitate cell replacement therapy. Early morphological evidence in Amphibia for the toti- or multipotentiality of some nuclei from differentiated cells first established the principle of the conservation of the genome during cell differentiation. Molecular markers show that many somatic cell nuclei are reprogrammed to an embryonic pattern of gene expression soon after nuclear transplantation to eggs. The germinal vesicles of oocytes in first meiotic prophase have a direct reprogramming activity on mammalian as well as amphibian nuclei and offer a route to identify nuclear reprogramming molecules. Amphibian eggs and oocytes have a truly remarkable ability to transcribe genes as DNA or nuclei, to translate mRNA, and to modify or localize proteins injected into them. The development of nuclear transplant embryos depends on the ability of cells to interpret small concentration changes of signal factors in the community effect and in morphogen gradients. Many difficulties in a career can be overcome by analyzing in increasing depth the same fundamentally interesting and important problem.
Collapse
Affiliation(s)
- J B Gurdon
- Wellcome Trust/Cancer Research UK Institute, Cambridge CB2 1QN, United Kingdom.
| |
Collapse
|
63
|
Ben-Haim N, Lu C, Guzman-Ayala M, Pescatore L, Mesnard D, Bischofberger M, Naef F, Robertson EJ, Constam DB. The nodal precursor acting via activin receptors induces mesoderm by maintaining a source of its convertases and BMP4. Dev Cell 2006; 11:313-23. [PMID: 16950123 DOI: 10.1016/j.devcel.2006.07.005] [Citation(s) in RCA: 239] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 06/29/2006] [Accepted: 07/14/2006] [Indexed: 11/17/2022]
Abstract
During early mouse development, the subtilisin-like proprotein convertases (SPC) Furin and PACE4 pattern the primitive ectoderm and visceral endoderm, presumably by activating the TGFss-related Nodal precursor. Here, mutation of the SPC motif provides direct evidence that Nodal processing is essential to specify anterior visceral endoderm and mesendoderm. Surprisingly, however, the Nodal precursor binds and activates activin receptors to maintain expression of Furin, PACE4, and Bmp4 in extraembryonic ectoderm at a distance from the Nodal source. In return, Bmp4 induces Wnt3, which amplifies Nodal expression in the epiblast and mediates induction of mesoderm. We conclude that uncleaved Nodal sustains the extraembryonic source of proprotein convertases and Bmp4 to amplify Nodal signaling in two nonredundant feedback loops with dual timescales and to localize primitive streak formation at the posterior pole. Based on mathematical modeling, we discuss how these sequential loops control cell fate.
Collapse
Affiliation(s)
- Nadav Ben-Haim
- Ecole Polytechnique Fédérale de Lausanne EPFL-ISREC, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
64
|
Abstract
The transforming growth factorbeta (TGFbeta) superfamily regulates a broad spectrum of biological responses throughout embryonic development and adult life, including cell proliferation and differentiation, epithelial-to-mesenchymal transition, apoptosis, and angiogenesis. TGFbeta members initiate signaling by bringing together a complex of serine/threonine kinase receptors that transmit signals through intracellular Smad proteins. Genetic alterations in numerous components of the TGFbeta signaling pathway have been associated with several human cancers. In addition, tight regulation of TGFbeta signaling is pivotal to the maintenance of homeostasis and the prevention of carcinogenesis. The ubiquitin/proteosome system is one mechanism by which cells regulate the expression and activity of effectors of the TGFbeta signaling cascade. Mounting evidence also suggests that disruption of the ubiquitin-dependent degradation of components of the TGFbeta pathway leads to the development and progression of cancer. Therefore, understanding how these two pathways intertwine will contribute to the advancement of our knowledge of cancer development.
Collapse
Affiliation(s)
- Luisa Izzi
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Liliana Attisano
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
65
|
Melnick M, Mocarski ES, Abichaker G, Huang J, Jaskoll T. Cytomegalovirus-induced embryopathology: mouse submandibular salivary gland epithelial-mesenchymal ontogeny as a model. BMC DEVELOPMENTAL BIOLOGY 2006; 6:42. [PMID: 16959038 PMCID: PMC1601957 DOI: 10.1186/1471-213x-6-42] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Accepted: 09/07/2006] [Indexed: 01/21/2023]
Abstract
BACKGROUND Human studies suggest, and mouse models clearly demonstrate, that cytomegalovirus (CMV) is dysmorphic to early organ and tissue development. CMV has a particular tropism for embryonic salivary gland and other head mesenchyme. CMV has evolved to co-opt cell signaling networks so to optimize replication and survival, to the detriment of infected tissues. It has been postulated that mesenchymal infection is the critical step in disrupting organogenesis. If so, organogenesis dependent on epithelial-mesenchymal interactions would be particularly vulnerable. In this study, we chose to model the vulnerability by investigating the cell and molecular pathogenesis of CMV infected mouse embryonic submandibular salivary glands (SMGs). RESULTS We infected E15 SMG explants with mouse CMV (mCMV). Active infection for up to 12 days in vitro results in a remarkable cell and molecular pathology characterized by atypical ductal epithelial hyperplasia, apparent epitheliomesenchymal transformation, oncocytic-like stromal metaplasia, beta-catenin nuclear localization, and upregulation of Nfkb2, Relb, Il6, Stat3, and Cox2. Rescue with an antiviral nucleoside analogue indicates that mCMV replication is necessary to initiate and maintain SMG dysmorphogenesis. CONCLUSION mCMV infection of embryonic mouse explants results in dysplasia, metaplasia, and, possibly, anaplasia. The molecular pathogenesis appears to center around the activation of canonical and, perhaps more importantly, noncanonical NFkappaB. Further, COX-2 and IL-6 are important downstream effectors of embryopathology. At the cellular level, there appears to be a consequential interplay between the transformed SMG cells and the surrounding extracellular matrix, resulting in the nuclear translocation of beta-catenin. From these studies, a tentative framework has emerged within which additional studies may be planned and performed.
Collapse
Affiliation(s)
- Michael Melnick
- Laboratory for Developmental Genetics, University of Southern California, Los Angeles, CA 90089-0641, USA
| | - Edward S Mocarski
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
| | - George Abichaker
- Laboratory for Developmental Genetics, University of Southern California, Los Angeles, CA 90089-0641, USA
| | - Jing Huang
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
| | - Tina Jaskoll
- Laboratory for Developmental Genetics, University of Southern California, Los Angeles, CA 90089-0641, USA
| |
Collapse
|