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Apposite insulin-like growth factor (IGF) receptor glycosylation is critical to the maintenance of vascular smooth muscle phenotype in the presence of factors promoting osteogenic differentiation and mineralization.

Siddals, Kirk W; Allen, Justine; Sinha, Smeeta; Canfield, Ann E; Kalra, Philip A; Gibson, J Martin

The Journal of biological chemistry. 2011;286(19):16623-30.

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Abstract

Vascular calcification is strongly linked with increased morbidity and mortality from cardiovascular disease. Vascular calcification is an active cell-mediated process that involves the differentiation of vascular smooth muscle cells (VSMCs) to an osteoblast-like phenotype. Several inhibitors of this process have been identified, including insulin-like growth factor-I (IGF-I). In this study, we examined the role of the IGF receptor (IGFR) and the importance of IGFR glycosylation in the maintenance of the VSMC phenotype in the face of factors known to promote osteogenic conversion. IGF-I (25 ng/ml) significantly protected VSMCs from β-glycerophosphate-induced osteogenic differentiation (p < 0.005) and mineral deposition (p < 0.01). Mevalonic acid depletion (induced by 100 nm cerivastatin) significantly inhibited these IGF protective effects (p < 0.01). Mevalonic acid depletion impaired IGFR processing, decreased the expression of mature IGFRs at the cell surface, and inhibited the downstream activation of Akt and MAPK. Inhibitors of N-linked glycosylation (tunicamycin, deoxymannojirimycin, and deoxynojirimycin) also markedly attenuated the inhibitory effect of IGF-I on β-glycerophosphate-induced mineralization (p < 0.05) and activation of Akt and MAPK. These results demonstrate that alterations in the glycosylation of the IGFR disrupt the ability of IGF-I to protect against the osteogenic differentiation and mineralization of VSMCs by several interrelated mechanisms: decreased IGFR processing, reduced IGFR cell-surface expression, and reduced downstream signaling via the Akt and MAPK pathways. IGF-I thus occupies a critical position in the maintenance of normal VSMC phenotype and protection from factors known to stimulate vascular calcification.

Bibliographic metadata

Type of resource:
Content type:
Publication type:
Publication form:
Published date:
Abbreviated journal title:
Place of publication:
United States
Volume:
286
Issue:
19
Pagination:
16623-30
Digital Object Identifier:
10.1074/jbc.M110.202929
Pubmed Identifier:
21454560
Pii Identifier:
M110.202929
Access state:
Active

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Manchester eScholar ID:
uk-ac-man-scw:138835
Created by:
Hookway, Sue
Created:
7th December, 2011, 15:34:29
Last modified by:
Hookway, Sue
Last modified:
11th March, 2014, 22:11:06