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Signaling in chemotaxis and development.

Zhang, Ning.

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Signaling in chemotaxis and development.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Signaling in chemotaxis and development./
Author:	Zhang, Ning.
Description:	123 p.
Notes:	Director: Peter N. Devreotes.
Contained By:	Dissertation Abstracts International62-10B.
Subject:	Biology, Cell. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3028354
ISBN:	0493405232

Signaling in chemotaxis and development.
Zhang, Ning.

Signaling in chemotaxis and development. - 123 p.

Director: Peter N. Devreotes.

Thesis (Ph.D.)--The Johns Hopkins University, 2002.

G protein-mediated signal transduction pathways control the developmental program of <italic>D. discoideum</italic>. In the conditions of starvation, free-living amoebae cells start to express early aggregative genes and synthesize signaling molecule, cAMP. Coordinated by secreted cAMP, 10<super>5</super> cells carry out chemotaxis to form an aggregate that differentiates into a spore on a stalk within 30 h. During this process, heterotrimeric G proteins mediate a repertoire of signaling pathways, including cAMP signal relay, induction of guanylyl cyclase and actin polymerization, and activation of transcriptional factors. These pathways play an essential role in development by regulating gene expression, chemotaxis, morphogenesis and pattern formation. Most of these signaling events are conserved in higher organism.

ISBN: 0493405232Subjects--Topical Terms:

1017686
Biology, Cell.

Signaling in chemotaxis and development.
LDR:03485nam 2200313 a 45 001 927203
005 20110425
008 110425s2002 eng d
020 $a 0493405232
035 $a (UnM)AAI3028354
035 $a AAI3028354
040 $a UnM $c UnM
100 1 $a Zhang, Ning. $3 1035476
245 1 0 $a Signaling in chemotaxis and development.
300 $a 123 p.
500 $a Director: Peter N. Devreotes.
500 $a Source: Dissertation Abstracts International, Volume: 62-10, Section: B, page: 4327.
502 $a Thesis (Ph.D.)--The Johns Hopkins University, 2002.
520 $a G protein-mediated signal transduction pathways control the developmental program of <italic>D. discoideum</italic>. In the conditions of starvation, free-living amoebae cells start to express early aggregative genes and synthesize signaling molecule, cAMP. Coordinated by secreted cAMP, 10<super>5</super> cells carry out chemotaxis to form an aggregate that differentiates into a spore on a stalk within 30 h. During this process, heterotrimeric G proteins mediate a repertoire of signaling pathways, including cAMP signal relay, induction of guanylyl cyclase and actin polymerization, and activation of transcriptional factors. These pathways play an essential role in development by regulating gene expression, chemotaxis, morphogenesis and pattern formation. Most of these signaling events are conserved in higher organism.
520 $a There has been 11 Gαs and one Gβ identified in <italic>Dictyostelium </italic> while the expected Gγ has long been missing. I report here the purification of a unique Gγ and isolation of its cDNA. Species wide sequence comparisons of Gγ subunits reveal a conserved secondary structure and a common CXXL motif that targets Gβγ subunits to plasma membrane. Overexpression of a CSVL-deleted Gγ (GγΔ) shifts endogenous Gβγ from the membrane to the cytosol and impairs development. The GγΔ cells fail to carry out chemotaxis in cAMP gradients. Surprisingly, an increment of cAMP can still induce G protein-mediated activation of adenylyl cyclase and guanylyl cyclase in GγΔ cells. Thus, a full complement of membrane-associated G proteins is required for gradient sensing, but is not necessary for responses to increments.
520 $a G proteins control the development program by regulating gene expression. A chemoattractant-activated signaling pathway, containing cAR1, G protein, and YAkA, is required for the expression of early aggregative genes. Using a restriction enzyme mediated insertional mutagenesis screen, I isolated an aggregation-defective mutant, <italic>ege A</italic><super>−</super>, and obtained its cDNA. Ege A, along with Ege B, belongs to a novel gene family that encodes cytosolic proteins containing a C2 domain. Its mRNA is expressed during the first 2 h of development while Ege B is expressed at later stage. Functional analysis data of <italic>null</italic> mutant indicate that Ege A is required for GPCR-mediated expression of aggregative genes. Its act is specific and other G protein-linked signaling pathways do not require Ege A.
590 $a School code: 0098.
650 4 $a Biology, Cell. $3 1017686
650 4 $a Biology, Genetics. $3 1017730
650 4 $a Biology, Molecular. $3 1017719
690 $a 0307
690 $a 0369
690 $a 0379
710 2 0 $a The Johns Hopkins University. $3 1017431
773 0 $t Dissertation Abstracts International $g 62-10B.
790 $a 0098
790 1 0 $a Devreotes, Peter N., $e advisor
791 $a Ph.D.
792 $a 2002
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3028354