Lysine residues of IGF-I are substrates for transglutaminases and modulate downstream IGF-I signalling

Sivaramakrishnan, Manaswini, Croll, Tristan I., Gupta, Rajesh, Stupar, Dario, Van Lonkhuyzen, Derek, Upton, Zee, & Shooter, Gary K. (2013) Lysine residues of IGF-I are substrates for transglutaminases and modulate downstream IGF-I signalling. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1833(12), pp. 3176-3185.

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Numerous studies have reported associations between IGF-I and other extra cellular matrix (ECM) proteins, including fibronectin (FN), integrins, IGF-binding proteins (IGFBPs) and through IGFBPs, with vitronectin (VN). Nevertheless, the precise nature and mechanisms of these interactions are still being characterised. In this paper, we discuss transglutaminases (TGases) as a constituent of the ECM and provide evidence for the first time that IGF-I is a lysine (K)-donor substrate to TGases. When IGF-I was incubated with an alpha-2 plasmin inhibitor-derived Q peptide in the presence of tissue transglutaminase (TG2), an IGF-I:Q peptide cross-linked species was detected using Western immunoblotting and confirmed by mass spectrometry. Similar findings were observed in the presence of Factor XIIIa (FXIIIa) TGase. To identify the precise location of this K-donor TGase site/s on IGF-I, all the three IGF-I K-sites, individually and collectively (K27, K65 and K68), were substituted to arginine (R) using site-directed mutagenesis. Incubation of these K→R IGF-I analogues with Q peptide in the presence of TG2 or FXIIIa resulted in the absence of cross-linking in IGF-I analogues bearing arginine substitution at site 68. This established that K68 within the IGF-I D-domain was the principal K-donor site to TGases. We further annotated the functional significance of these K→R IGF-I analogues on IGF-I mediated actions. IGF-I analogues with K→R substitution within the D-domain at K65 and K68 hindered migration of MCF-7 breast carcinoma cells and correspondingly reduced PI3-K/AKT activation. Therefore, this study also provides first insights into a possible functional role of the previously uncharacterised IGF-I D-domain.

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ID Code: 62629
Item Type: Journal Article
Refereed: Yes
Keywords: Insulin-like growth factor, IGF, D-domain of IGF-I, transglutaminases, migration, viability, TG2
DOI: 10.1016/j.bbamcr.2013.09.002
ISSN: 0006-3002
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > BIOCHEMISTRY AND CELL BIOLOGY (060100)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2013 Elsevier
Copyright Statement: This is the author’s version of a work that was accepted for publication in Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, [Vol 1833, Issue 12, (2013)] DOI: 10.1016/j.bbamcr.2013.09.002
Deposited On: 18 Sep 2013 22:36
Last Modified: 16 Jul 2017 16:39

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