Integrin Alpha Subunit Expression and Cytoplasmic Domain Function

The β\sb1 integrins are a family of αβ heterodimeric cell surface receptors which mediate cell adhesion to molecules of the extracellular matrix (ECM), and also span the membrane and associate with the cytoskeleton via their cytoplasmic domains. By mediating the interaction of the cellular cytoskeleton with the ECM, the β\sb1 integrins are central to issues of cell migration, proliferation, differentiation, cytoskeletal organization, cell morphology, and the maintenance of tissue architecture and integrity. The focus of this work has been to investigate the expression and function of individual chicken β\sb1 integrin family members. First, the integrins were affinity purified from various adult chicken tissues to reveal the diversity and differential expression of the chicken β\sb1 integrins. The purified receptors were then used to immunize mice and generate monoclonal antibodies (mAbs) against the α subunits which distinguish each receptor. Antibodies were generated against two α subunits (i.e. two receptors), and were used to identify these α subunits as homologs of the human α\sb5 subunit (a fibronectin receptor) and human α\sb6 subunit (a laminin receptor). Also, the cross-reaction with chicken α subunits of antisera specific for the human α subunit cytoplasmic domains revealed conserved sequences, and presumably a conserved function, within each α subunit cytoplasmic domain. Immuno-cytochemistry studies using the anti-α\sb5 and anti-α\sb6 mAbs revealed: (1) the cell-specific expression of the receptors; (2) the changes in receptor expression during embryonic development; and (3) the localization of the receptors in specific membrane-cytoskeletal junctions. The observed junctional specificity of the receptors suggested a unique recognition between cytoskeletal molecules at each membrane-cytoskeleton junction and the integrin α subunit cytoplasmic domains. We have initiated mutagenesis studies to dissect the function(s) within the α subunit cytoplasmic domains. In addition, we have generated antibodies against an apparently novel integrin-associated cytoskeletal protein complex. These antibodies have permitted investigations of the composition and molecular associations at specific integrin-cytoskeleton junctions, and lead to the identification and characterization of several novel cytoskeletal molecules which are components of these junctions.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Muschler, John Leonard

Contributors dc:contributor

• Horwitz, A.,

• Biology, Cell
• Chemistry, Biochemistry

Identifier

(UMI)AAI9329116

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/72357