Disruption of C-terminal cytoplasmic domain of betaPS integrin subunit has dominant negative properties in developing Drosophila.
We have analyzed a set of new and existing strong mutations in the myospheroid gene, which encodes the betaPS integrin subunit of Drosophila. In addition to missense and other null mutations, three mutants behave as antimorphic alleles, indicative of dominant negative properties. Unlike null alleles, the three antimorphic mutants are synthetically lethal in double heterozygotes with an inflated (alphaPS2) null allele, and they fail to complement very weak, otherwise viable alleles of myospheroid. Two of the antimorphs result from identical splice site lesions, which create a frameshift in the C-terminal half of the cytoplasmic domain of betaPS. The third antimorphic mutation is caused by a stop codon just before the cytoplasmic splice site. These mutant betaPS proteins can support cell spreading in culture, especially under conditions that appear to promote integrin activation. Analyses of developing animals indicate that the dominant negative properties are not a result of inefficient surface expression, or simple competition between functional and nonfunctional proteins. These data indicate that mutations disrupting the C-terminal cytoplasmic domain of integrin beta subunits can have dominant negative effects in situ, at normal levels of expression, and that this property does not necessarily depend on a specific new protein sequence or structure. The results are discussed with respect to similar vertebrate beta subunit cytoplasmic mutations.
Jannuzi
Alison L
AL
Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA.
Bunch
Thomas A
TA
Brabant
Marc C
MC
Miller
Steven W
SW
Mukai
Leona
L
Zavortink
Michael
M
Brower
Danny L
DL
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins; D005799:Genes, Dominant; D005838:Genotype; D039001:Integrin alpha Chains; D016023:Integrins / Q000737:chemistry*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D020125:Mutation, Missense; D010641:Phenotype; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014921:Wings, Animal / Q000196:embryology
D029721:Drosophila Proteins; D039001:Integrin alpha Chains; D016023:Integrins; D012333:RNA, Messenger; C082188:if protein, Drosophila; D012313:RNA