Project Title

Design, Molecular Cloning and Expression of Integrin αD Mutants for the Functional Analysis of Integrin Ligand Binding Properties

Authors' Affiliations

Diego Razura, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN. Valentin Yakubenko, Department of Biomedical Sciences, Center of Excellence for Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN. Jared Casteel, Department of Biomedical Sciences, Center of Excellence for Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, TN. Kasey Keever, Department of Biomedical Sciences, Center of Excellence for Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, TN.

Location

Culp Ballroom

Start Date

4-7-2022 9:00 AM

End Date

4-7-2022 12:00 PM

Poster Number

1

Faculty Sponsor’s Department

Biomedical Sciences

Name of Project's Faculty Sponsor

Valentin Yakubenko

Classification of First Author

Medical Student

Competition Type

Competitive

Type

Poster Presentation

Project's Category

Inflammation, Cardiovascular Disease, Chronic Illnesses, Diabetes

Abstract or Artist's Statement

The accumulation of pro-inflammatory macrophages in the inflamed vascular wall is a critical step in atherogenesis. The mechanism of macrophage retention within the site of inflammation is not understood yet. High adhesion that prevents macrophage migration is one of the potential mechanisms. Previous research in our laboratory showed that integrin αDβ2 is upregulated on pro-inflammatory macrophages, promotes macrophage retention, and contributes to atherogenesis. However, a key ligand for αDβ2 within the tissue is yet to be identified, since αDβ2 does not interact with major ECM proteins, collagens, and laminins. We recently found that during acute inflammation, the oxidation of docosahexaenoic acid (DHA) leads to the generation of end product carboxyethylpyrrole (CEP), which forms an adduct with fibrinogen and albumin via ε-amino group of lysines. There is evidence that macrophages adhere to CEP-modified albumin in αDβ2-dependent manner.

We continued the advancement of the proposed hypothesis that non-conserved, basic amino acids of integrin αDβ2 located near the MIDAS site of the I-domain are responsible for binding to CEP. αD I-domain and generated I-domain mutants: H272(D), K297(Q) and K309(N) were used to map the ligand binding site between integrin and CEP. Using site-directed mutagenesis, mutant αD I-domains were generated with minimal amino acid substitutions. Protein-protein binding reveals that the generated mutation of K297(Q) on the I-domain demonstrates the strong reduction of binding, while H272(D) and K309(N) did not have a significant effect on integrin binding properties. Therefore, lysine 297 located in I-domain of integrin αD, is a critical amino acid for αDβ2 binding to CEP-modified proteins.

The identification of a binding site for CEP-modified proteins within αDβ2 will help to develop a blocking reagent for the treatment of the inflammatory component of atherosclerosis.

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Apr 7th, 9:00 AM Apr 7th, 12:00 PM

Design, Molecular Cloning and Expression of Integrin αD Mutants for the Functional Analysis of Integrin Ligand Binding Properties

Culp Ballroom

The accumulation of pro-inflammatory macrophages in the inflamed vascular wall is a critical step in atherogenesis. The mechanism of macrophage retention within the site of inflammation is not understood yet. High adhesion that prevents macrophage migration is one of the potential mechanisms. Previous research in our laboratory showed that integrin αDβ2 is upregulated on pro-inflammatory macrophages, promotes macrophage retention, and contributes to atherogenesis. However, a key ligand for αDβ2 within the tissue is yet to be identified, since αDβ2 does not interact with major ECM proteins, collagens, and laminins. We recently found that during acute inflammation, the oxidation of docosahexaenoic acid (DHA) leads to the generation of end product carboxyethylpyrrole (CEP), which forms an adduct with fibrinogen and albumin via ε-amino group of lysines. There is evidence that macrophages adhere to CEP-modified albumin in αDβ2-dependent manner.

We continued the advancement of the proposed hypothesis that non-conserved, basic amino acids of integrin αDβ2 located near the MIDAS site of the I-domain are responsible for binding to CEP. αD I-domain and generated I-domain mutants: H272(D), K297(Q) and K309(N) were used to map the ligand binding site between integrin and CEP. Using site-directed mutagenesis, mutant αD I-domains were generated with minimal amino acid substitutions. Protein-protein binding reveals that the generated mutation of K297(Q) on the I-domain demonstrates the strong reduction of binding, while H272(D) and K309(N) did not have a significant effect on integrin binding properties. Therefore, lysine 297 located in I-domain of integrin αD, is a critical amino acid for αDβ2 binding to CEP-modified proteins.

The identification of a binding site for CEP-modified proteins within αDβ2 will help to develop a blocking reagent for the treatment of the inflammatory component of atherosclerosis.