Identification of Inhibitors of Integrin Cytoplasmic Domain Interactions With Syk

Abstract

Leukocyte inflammatory responses require integrin cell-adhesion molecule signaling through spleen tyrosine kinase (Syk), a non-receptor kinase that binds directly to integrin β-chain cytoplasmic domains. Here, we developed a high-throughput screen to identify small molecule inhibitors of the Syk-integrin cytoplasmic domain interactions. Screening small molecule compound libraries identified the β-lactam antibiotics cefsulodin and ceftazidime, which inhibited integrin β-subunit cytoplasmic domain binding to the tandem SH2 domains of Syk (IC50 range, 1.02–4.9 µM). Modeling suggested antagonist binding to Syk outside the pITAM binding site. Ceftazidime inhibited integrin signaling via Syk, including inhibition of adhesion-dependent upregulation of interleukin-1β and monocyte chemoattractant protein-1, but did not inhibit ITAM-dependent phosphorylation of Syk mediated by FcγRI signaling. Our results demonstrate a novel means to target Syk independent of its kinase and pITAM binding sites such that integrin signaling via this kinase is abrogated but ITAM-dependent signaling remains intact. As integrin signaling through Syk is essential for leukocyte activation, this may represent a novel approach to target inflammation.

A Small Molecule That In Vitro Neutralizes Infection of SARS-CoV-2 and Its Most Infectious Variants, Delta, and Omicron

“…Since the SARS-CoV-2 virus enters host cells via an interaction between its spike protein and the host cell receptor angiotensin-converting enzyme 2 (ACE2) [ 10 ], our goal was therefore to disrupt this interaction with a small molecule. To disrupt this protein-protein interaction, we performed in silico screening following our Cloud workflow implementation using Microsoft Azure and the University of Houston’s Hewlett Packard Enterprise (HPE) Data Science Institute to execute our drug discovery workflow [ 7 , 8 ] by using AutoDock Vina version 1.2.0, GROMACS 2021.5, and PySpark 3.3.2. Candidate in silico binding poses of compounds to the SARS-CoV-2 spike protein were generated from over a million compounds from the Maybridge and ZINC libraries.…”

“…Following well-established protocols, structures from the protein data bank (PDB files 6M0J, 6VXX, and 6VYB) were used to prepare the structural models of the SARS-CoV-2 spike protein receptor binding site and the ACE2 receptor [ 5 , 6 ]. CD04872SC was initially expanded into its 3D minimized structure using BALLOON 3-1.6.6 and then processed with PRODRG4 to build topology files [ 7 , 8 ]. Both the spike protein and the ligand were prepared for docking analysis using AUTODOCK-TOOLS version 4 and AUTODOCK_VINA 1.1.2.…”

Inhibitory Effects of Grewia tomentosa Juss. on IgE-Mediated Allergic Reaction and DNCB-Induced Atopic Dermatitis

“…FcεRI aggregation results in phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs), which are located in the cytoplasm of FcεRI. Phosphorylated ITAMs provide a docking site for the signal-propagating kinase Syk, which is activated and autophosphorylated by binding to ITAMs [ 12 ]. Syk phosphorylation leads to activation of numerous signaling molecules, including phospholipase Cγ (PLCγ) and phosphatidylinositol 3-kinase (PI3K) [ 13 ].…”