Platelet receptor alpha-IIb-beta3 belongs to a class of cell adhesion receptors, the integrins. alpha-IIb-beta3 mediates platelet aggregation, which is essential for hemostasis but also can result in the formation of acute occlusive thrombi, leading to heart attacks and strokes. Central to the function of alpha-IIb-beta3 is its capacity to undergo activation, a transition from a low to a high affinity/avidity state for ligand recognition. The small cytoplasmic face of alpha-IIb-beta3 regulates such transition through a distinct process called """"""""inside-out"""""""" signaling, i.e., upon platelet stimulation by agonists, such as thrombin or ADP, the cytoplasmic face of alpha-IIb-beta3 undergoes a conformational change that propagates to the extracellutar domain allowing it to bind soluble fibrinogen or von Willebrand Factor with high affinity. The exact signal(s) or protein(s) that directly initiates this conformational change has been under intensive investigation over the past decade. Talin provides a model for one such activating signal. Talin is a cytoskeletal protein that binds directly to the alpha-IIb-beta3 cytoplasmic face and activates the receptor. Deletion and biochemical analyses revealed that the N-terminal head domain of talin (talin-H) or its smaller fragment (talin-HS) specifically recognizes the beta3 cytoplasmic tail and is responsible for inducing the alpha-IIb-beta3 activation. Interestingly, intact talin has significantly lower affinity for the beta3 tail than the isolated talin-H, suggesting a conformation-based regulatory process for the talin-beta3 interaction. A molecular level understanding of the talin-beta3 interaction in regulating the alpha-IIb-beta3 activation remains unclear. We propose to address this issue by using highly integrated and systematic structural/biochemical approaches. We will determine NMR structure of the talin-HS domain (27 kDa) in complex with the beta3 cytoplasmic tail (5 kDa) and perform structure-based mutagenesis to evaluate the significance of the interaction in mediating the integrin activation. We will also examine other factors in regulating the integrin activation such as tyrosine-phosphorylation and integrin-skelemin interaction. Finally we will investigate how the talin-H/beta3 interaction undergoes the transition from a lower affinity state to a higher affinity state. These studies will significantly impact on understanding the mechanisms of alpha-IIb-beta3 activation, which will ultimately provide insight into a fundamental process in thrombosis.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Program Projects (P01)
Project #
Application #
Study Section
Heart, Lung, and Blood Initial Review Group (HLBP)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Cleveland Clinic Lerner
United States
Zip Code
Szpak, Dorota; Izem, Lahoucine; Verbovetskiy, Dmitriy et al. (2018) ?M?2 Is Antiatherogenic in Female but Not Male Mice. J Immunol 200:2426-2438
Plow, Edward F; Wang, Yunmei; Simon, Daniel I (2018) The search for new antithrombotic mechanisms and therapies that may spare hemostasis. Blood 131:1899-1902
Sossey-Alaoui, Khalid; Pluskota, Elzbieta; Szpak, Dorota et al. (2018) The Kindlin-2 regulation of epithelial-to-mesenchymal transition in breast cancer metastasis is mediated through miR-200b. Sci Rep 8:7360
Gao, Detao; Podrez, Eugene A (2018) Characterization of covalent modifications of HDL apoproteins by endogenous oxidized phospholipids. Free Radic Biol Med 115:57-67
Bledzka, Kamila; Schiemann, Barbara; Schiemann, William P et al. (2017) The WAVE3-YB1 interaction regulates cancer stem cells activity in breast cancer. Oncotarget 8:104072-104089
Sossey-Alaoui, Khalid; Pluskota, Elzbieta; Bialkowska, Katarzyna et al. (2017) Kindlin-2 Regulates the Growth of Breast Cancer Tumors by Activating CSF-1-Mediated Macrophage Infiltration. Cancer Res 77:5129-5141
Ding, Liang; Zhang, Lifang; Kim, Michael et al. (2017) Akt3 kinase suppresses pinocytosis of low-density lipoprotein by macrophages via a novel WNK/SGK1/Cdc42 protein pathway. J Biol Chem 292:9283-9293
Biswas, Sudipta; Zimman, Alejandro; Gao, Detao et al. (2017) TLR2 Plays a Key Role in Platelet Hyperreactivity and Accelerated Thrombosis Associated With Hyperlipidemia. Circ Res 121:951-962
Wang, Yunmei; Gao, Huiyun; Shi, Can et al. (2017) Leukocyte integrin Mac-1 regulates thrombosis via interaction with platelet GPIb?. Nat Commun 8:15559
Meller, Julia; Chen, Zhihong; Dudiki, Tejasvi et al. (2017) Integrin-Kindlin3 requirements for microglial motility in vivo are distinct from those for macrophages. JCI Insight 2:

Showing the most recent 10 out of 105 publications