BACKGROUND: The highly conserved integrin alpha-subunit membrane-proximal motif KVGFFKR plays a decisive role in modulating the activation of integrin alphaIIbbeta3. Previously, we have shown that a platelet permeable palmityl (pal)-peptide with this seven amino acid sequence can directly activate alphaIIbbeta3 leading to platelet aggregation. OBJECTIVES: To investigate further the role of the KVGFFKR motif in integrin alphaIIbbeta3 function. METHODS: We used two sequence-specific complementary model systems, palmityl pal-peptides in platelets, and mutant alphaIIbbeta3-expressing Chinese Hamster Ovary (CHO) cell lines. RESULTS: In platelets we show that the two phenylalanine amino acids in pal-KVGFFKR (pal-FF) peptide are critical for stimulating platelet aggregation. Pal-FF peptide treatment of platelets also gives rise to a tyrosine phosphorylation signal despite the presence of inhibitors of fibrinogen binding. In CHO cells, a double alanine substitution, alphaIIb(F992A, F993A)beta3, induces constitutive integrin activation but prevents actin stress fiber formation upon adhesion to fibrinogen, suggesting that alphaIIbbeta3-mediated cytoskeletal reorganization is also dependent on F992 and F993. This further highlights a critical role for the two phenylalanine residues in both of these alphaIIbbeta3-mediated processes. CONCLUSION: In addition to regulating integrin alphaIIbbeta3 activation state, the KVGFFKR motif also influences cytoskeletal reorganization. This activity is critically determined by F992 and F993 within the seven amino acid sequence.
BACKGROUND: The highly conserved integrin alpha-subunit membrane-proximal motif KVGFFKR plays a decisive role in modulating the activation of integrin alphaIIbbeta3. Previously, we have shown that a platelet permeable palmityl (pal)-peptide with this seven amino acid sequence can directly activate alphaIIbbeta3 leading to platelet aggregation. OBJECTIVES: To investigate further the role of the KVGFFKR motif in integrin alphaIIbbeta3 function. METHODS: We used two sequence-specific complementary model systems, palmityl pal-peptides in platelets, and mutant alphaIIbbeta3-expressing Chinese Hamster Ovary (CHO) cell lines. RESULTS: In platelets we show that the two phenylalanine amino acids in pal-KVGFFKR (pal-FF) peptide are critical for stimulating platelet aggregation. Pal-FF peptide treatment of platelets also gives rise to a tyrosine phosphorylation signal despite the presence of inhibitors of fibrinogen binding. In CHO cells, a double alanine substitution, alphaIIb(F992A, F993A)beta3, induces constitutive integrin activation but prevents actin stress fiber formation upon adhesion to fibrinogen, suggesting that alphaIIbbeta3-mediated cytoskeletal reorganization is also dependent on F992 and F993. This further highlights a critical role for the two phenylalanine residues in both of these alphaIIbbeta3-mediated processes. CONCLUSION: In addition to regulating integrin alphaIIbbeta3 activation state, the KVGFFKR motif also influences cytoskeletal reorganization. This activity is critically determined by F992 and F993 within the seven amino acid sequence.
Authors: Daniel K Shanley; Patrick A Kiely; Kalyan Golla; Seamus Allen; Kenneth Martin; Ronan T O'Riordan; Melanie Ball; John D Aplin; Bernhard B Singer; Noel Caplice; Niamh Moran; Tom Moore Journal: PLoS One Date: 2013-02-28 Impact factor: 3.240
Authors: Kevin T O'Brien; Kalyan Golla; Tilen Kranjc; Darragh O'Donovan; Seamus Allen; Patricia Maguire; Jeremy C Simpson; David O'Connell; Niamh Moran; Denis C Shields Journal: PLoS One Date: 2019-01-28 Impact factor: 3.240