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Identification of a proline-rich sequence in the CD2 cytoplasmic domain critical for regulation of integrin-mediated adhesion and activation of phosphoinositide 3-kinase.
Identification of a proline-rich sequence in the CD2 cytoplasmic domain critical for regulation of integrin-mediated adhesion and activation of phosphoinositide 3-kinase.
- Source :
-
Molecular and cellular biology [Mol Cell Biol] 1998 Sep; Vol. 18 (9), pp. 5291-307. - Publication Year :
- 1998
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Abstract
- The CD2 molecule is one of several lymphocyte receptors that rapidly initiates signaling events regulating integrin-mediated cell adhesion. CD2 stimulation of resting human T cells results within minutes in an increase in beta1-integrin-mediated adhesion to fibronectin. We have utilized the HL60 cell line to map critical residues within the CD2 cytoplasmic domain involved in CD2 regulation of integrin function. A panel of CD2 cytoplasmic domain mutants was constructed and analyzed for their ability to upregulate integrin-mediated adhesion to fibronectin. Mutations in the CD2 cytoplasmic domain implicated in CD2-mediated interleukin-2 production or CD2 avidity do not affect CD2 regulation of integrin activity. A proline-rich sequence, K-G-P-P-L-P (amino acids 299 to 305), is essential for CD2-mediated regulation of beta1 integrin activity. CD2-induced increases in beta1 integrin activity could be blocked by two phosphoinositide 3-kinase (PI 3-K) inhibitors or by overexpression of a dominant negative form of the p85 subunit of PI 3-K. In addition, CD2 cytoplasmic domain mutations that abrogate CD2-induced increases in integrin-mediated adhesion also ablate CD2-induced increases in PI 3-K enzymatic activity. Surprisingly, CD2 cytoplasmic domain mutations that inhibit CD2 regulation of adhesion do not affect the constitutive association of the p85 subunit of PI 3-K association with CD2. Mutation of the proline residues in the K-G-P-P-L-P motif to alanines prevented CD2-mediated activation of integrin function and PI 3-K activity but not mitogen-activated protein (MAP) kinase activity. Furthermore, the MEK inhibitor PD 098059 blocked CD2-mediated activation of MAP kinase but had no effect on CD2-induced adhesion. These studies identify a proline-rich sequence in CD2 critical for PI 3-K-dependent regulation of beta1 integrin adhesion by CD2. In addition, these studies suggest that CD2-mediated activation of MAP kinase is not involved in CD2 regulation of integrin adhesion.
- Subjects :
- Amino Acid Sequence
Antigens, CD biosynthesis
Antigens, CD chemistry
Antigens, CD physiology
CD2 Antigens biosynthesis
Calcium-Calmodulin-Dependent Protein Kinases metabolism
Cytoplasm
Enzyme Activation
Fibronectins physiology
Glutathione Transferase metabolism
HL-60 Cells
Humans
Kinetics
Molecular Sequence Data
Mutagenesis, Site-Directed
Recombinant Fusion Proteins biosynthesis
Recombinant Fusion Proteins chemistry
T-Lymphocytes immunology
Transfection
CD2 Antigens chemistry
CD2 Antigens physiology
Integrin beta1 physiology
Phosphatidylinositol 3-Kinases metabolism
Proline
T-Lymphocytes physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0270-7306
- Volume :
- 18
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Molecular and cellular biology
- Publication Type :
- Academic Journal
- Accession number :
- 9710614
- Full Text :
- https://doi.org/10.1128/MCB.18.9.5291