APPLICATIONS:

• Single dose drug therapy for preventing restenosis and reducing the effects of acute phase response

ADVANTAGES:

• Promises to help prevent restenosis and thereby reduce the frequency of repeated invasive procedures to clear arterial blockages
  
• Potentially inhibits the harmful oxidative effects of acute phase response
  
• Increases paraoxonase activity by up to 30%

	Cysteine (cys) mutations in the N-terminal third of apoA-1 (R10C, R27C, and R61C) (green) elevated arylesterase activity by approximately 30% over wild type apoA-1 (black). Arylesterase is one of the two enzymatic activities of PON. Cys substitutions in the C-terminal portion of apoA-1 (gold) show no increase in PON arylesterase activity. (See background section for more explanation.)

ABSTRACT:

Trudy Forte and Michael Oda have developed functional apolipoprotein A-1 (apoA-1) mutant proteins and their encoding polynucleotides that increase the anti-oxidating activity of paraoxonase (PON) by as much as 30% compared to the effect of naturally occurring apoA-1. A single post-operative dose of a drug based on the Berkeley Lab apoA-1 variants could reduce the probability of restenosis and alleviate the harmful oxidative effects of acute phase response, thereby reducing the frequency of repeated invasive procedures.

According to the American Heart Association, in 10-20% of the patients who undergo balloon angioplasty, the affected portion of the artery reverts to its occluded state within six months. This condition, restenosis, is usually initiated during the acute phase response, which occurs immediately following the angioplasty or stent procedure.

Patients who exhibit restenosis are generally treated with a second balloon angioplasty and/or stent implementation procedure. Sometimes the only option is coronary bypass surgery. The Berkeley Lab apoA-1 protein variants make feasible the preparation and administration, either orally or intravenously, of therapies that could reduce the risk of restenosis and the effects of acute phase response.

The Berkeley Lab researchers modified the natural form of the DNA encoding human apoA-1 to introduce a series of restriction sites. These restriction sites facilitated the creation of three unique mutation forms of apoA-I which contain a cysteine substitution at amino acid positions 10, 27 and 61, respectively. These cysteine substitutions are correlated with a significant increase in PON’s anti-oxidating activity. Indications are that the cysteine on apoA-1 serves to enhance the efficiency of PON’s enzymatic activity but does not increase the amount of the enzyme. HDL bearing multiple apoA-1 mutant proteins may possess further elevated PON activity.

Background:

ApoA-1 is the major structural protein on high density lipoprotein (HDL). It is largely responsible for mediating HDL assembly and helps determine HDL structure and composition. The enzyme PON is exclusively transported on plasma HDL. HDL with PON protects low density lipoprotein (LDL) from oxidation. Since oxidized LDL plays a significant role in developing atherosclerotic lesions, PON’s anti-oxidative influence helps protect the arteries from atherogenesis, restenosis, and other oxidative incidents. Since PON is a highly potent inhibitor of oxidative events, even a modest increase in PON activity could lead to large downstream effects on physiological markers such as atherosclerosis.

STATUS:

• Issued Patent # 7,223,726. Available for licensing or collaborative research.

PUBLICATION:

Oda M.N., Bielicki J.K., Berger T., Forte T.M., “Cysteine Substitutions in Apolipoprotein A-1 Primary Structure Modulate Paraoxonase Activity,” Biochemistry, 2001, 40, 1710-18.

REFERENCE NUMBER: IB-1713