Published Online
on July 21, 2003

A more recent version of this article appeared on August 5, 2003

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Submitted on July 29, 2002
Revised on April 29, 2003
Accepted on May 2, 2003

Cloning of a Novel Prolyl 4-Hydroxylase Subunit Expressed in the Fibrous Cap of Human Atherosclerotic Plaque

Caroline Van Den Diepstraten MSc, Karen Papay MSc, Zuzana Bolender MSc, Arthur Brown PhD, and J. Geoffrey Pickering MD, PhD^*

From the Robarts Research Institute (Vascular Biology Group), London Health Sciences Centre, Departments of Medicine (Cardiology), Biochemistry, Medical Biophysics, University of Western Ontario, London, Canada.

^* To whom correspondence should be addressed. E-mail: gpickering{at}robarts.ca.

Background--The production of collagen is fundamental to atherosclerosis and critically dependent on posttranslational modification by prolyl 4-hydroxylase.

Methods and Results--We report the cloning of a novel prolyl 4-hydroxylase catalytic () subunit from human vascular smooth muscle cells. The peptide displayed conservation of critical residues for interacting with Fe²⁺ and 2-oxoglutarate, essential cosubstrates for prolyl 4-hydroxylase activity. Furthermore, when the recombinant protein was expressed in cells, it associated with the -subunit of prolyl 4-hydroxylase and could catalyze prolyl 4-hydroxylation of a collagen-like peptide. The tissue distribution was dissimilar from that of the 2 previously cloned -subunits, suggesting a role beyond redundancy. Importantly, the novel gene was expressed in the fibrous cap of human carotid atherosclerotic lesions.

Conclusions--The discovery of a novel prolyl 4-hydroxylase -subunit, here termed the (III)-subunit, suggests a new participant in collagen synthesis that, in view of the expression findings, may be relevant to atherosclerotic disease.

Key words: atherosclerosis • muscle, smooth • collagen • genes

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