Mechanisms of Has2 Regulation and Hyaluronan Signaling During Embryonic Development

Persistent Link:
http://hdl.handle.net/10150/195566
Title:
Mechanisms of Has2 Regulation and Hyaluronan Signaling During Embryonic Development
Author:
Craig, Evisabel Arauz
Issue Date:
2010
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The cardiovasculature is the first functional system in the developing embryo and as such, it plays a crucial role in the proper nourishment and formation of all other body regions and organs. A detailed understanding the mechanisms that regulate cardiac morphogenesis is necessary to develop possible strategies for diagnostics and treatment of cardiovascular diseases.One molecule identified as important for the proper formation of the heart is Hyaluronan synthase 2 (Has2), a membrane protein in charge of assembling the glycosaminoglycan hyaluronan (HA). Mouse embryos lacking Has2 do not produce HA, display severe cardiovascular abnormalities and die during early embryogenesis. Thus, Has2 and HA are necessary for the early stages of heart formation, but many questions remain to be answered in regards to their mechanism of action and their role in later events such as the formation of the coronary vessels. Our current study addresses these questions employing two cell lines: NIH-3T3s, as a model of mesenchymal endocardial cushion cells; and epicardial cells, which have an epithelial phenotype.Here we show that HA induces biological activity in embryonic cells in a manner that is dependent on its molecular size. High molecular weight HA (HMW-HA), but not low molecular weight HA (LMW-HA), induces invasion of NIH-3T3 cells while it promotes differentiation and invasion of epicardial cells. We also demonstrate that stimulation of cells with HMW-HA promotes the association of MEKK1 with the HA receptor CD44. This leads to the activation of two distinct pathways, one ERK-dependent and another NFκB-dependent, which are crucial for the induction of cellular responsesFinally, we have demonstrated that the growth factors TGFβ2 and EGF induce Has2 expression and/or phosphorylation. TGFβ2 governs Has2 via MEKK3-dependent mechanisms, while EGF does not require MEKK3. Increased Has2 activity as a result of TGFβ2 and EGF stimulation leads to enhanced HA synthesis. These increased levels of HA are coincident with enhanced cellular differentiation and invasion. Taken together, these findings underscore how EGF, TGFβ2 and HA signals are integrated to form highly complex networks that are crucial for the proper formation of organs and tissues during development.
Type:
text; Electronic Dissertation
Keywords:
development; EMT; Has2; heart; hyaluronan
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Pharmacology & Toxicology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Camenisch, Todd D
Committee Chair:
Camenisch, Todd D

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleMechanisms of Has2 Regulation and Hyaluronan Signaling During Embryonic Developmenten_US
dc.creatorCraig, Evisabel Arauzen_US
dc.contributor.authorCraig, Evisabel Arauzen_US
dc.date.issued2010en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe cardiovasculature is the first functional system in the developing embryo and as such, it plays a crucial role in the proper nourishment and formation of all other body regions and organs. A detailed understanding the mechanisms that regulate cardiac morphogenesis is necessary to develop possible strategies for diagnostics and treatment of cardiovascular diseases.One molecule identified as important for the proper formation of the heart is Hyaluronan synthase 2 (Has2), a membrane protein in charge of assembling the glycosaminoglycan hyaluronan (HA). Mouse embryos lacking Has2 do not produce HA, display severe cardiovascular abnormalities and die during early embryogenesis. Thus, Has2 and HA are necessary for the early stages of heart formation, but many questions remain to be answered in regards to their mechanism of action and their role in later events such as the formation of the coronary vessels. Our current study addresses these questions employing two cell lines: NIH-3T3s, as a model of mesenchymal endocardial cushion cells; and epicardial cells, which have an epithelial phenotype.Here we show that HA induces biological activity in embryonic cells in a manner that is dependent on its molecular size. High molecular weight HA (HMW-HA), but not low molecular weight HA (LMW-HA), induces invasion of NIH-3T3 cells while it promotes differentiation and invasion of epicardial cells. We also demonstrate that stimulation of cells with HMW-HA promotes the association of MEKK1 with the HA receptor CD44. This leads to the activation of two distinct pathways, one ERK-dependent and another NFκB-dependent, which are crucial for the induction of cellular responsesFinally, we have demonstrated that the growth factors TGFβ2 and EGF induce Has2 expression and/or phosphorylation. TGFβ2 governs Has2 via MEKK3-dependent mechanisms, while EGF does not require MEKK3. Increased Has2 activity as a result of TGFβ2 and EGF stimulation leads to enhanced HA synthesis. These increased levels of HA are coincident with enhanced cellular differentiation and invasion. Taken together, these findings underscore how EGF, TGFβ2 and HA signals are integrated to form highly complex networks that are crucial for the proper formation of organs and tissues during development.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectdevelopmenten_US
dc.subjectEMTen_US
dc.subjectHas2en_US
dc.subjecthearten_US
dc.subjecthyaluronanen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePharmacology & Toxicologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorCamenisch, Todd Den_US
dc.contributor.chairCamenisch, Todd Den_US
dc.contributor.committeememberRegan, Johnen_US
dc.contributor.committeememberVaillancourt, Richarden_US
dc.contributor.committeememberStamer, William Den_US
dc.contributor.committeememberKlimecki, Walteren_US
dc.identifier.proquest11247en_US
dc.identifier.oclc752261091en_US
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