Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving antigen-antibody binding – specific binding protein...
Reexamination Certificate
1998-05-12
2002-04-23
Ulm, John (Department: 1646)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving antigen-antibody binding, specific binding protein...
C435S069700, C536S023400
Reexamination Certificate
active
06376198
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to peptide hormone receptors.
Peptide hormone receptors are important targets for drug research because a considerable number of diseases and other adverse effects result from abnormal receptor activity. High affinity, high specificity, non-peptide antagonists for peptide hormone receptors have been developed. These antagonists are therapeutically useful for decreasing receptor activation by endogenous hormones. Developing non-peptide agonists proved to be far more difficult.
One peptide hormone of interest, cholecystokinin (CCK), is a neuropeptide with two distinct receptors: CCK-A and CCK-B/gastrin (Vanderhaeghen et al.,
Nature
, 257:604-605, 1975; Dockray,
Nature
, 264:568-570, 1976; Rehfeld,
J. Biol. Chem.,
253:4022-4030, 1978; Hill et al.,
Brain Res
., 526:276-283, 1990; Hill et al.,
J. Neurosci
., 10:1070-1081, 1990; Woodruff et al.,
Neuropeptides
, (Suppl.) 19:57-64, 1991). The peripheral type receptor CCK-A is located in discrete brain nuclei and, in certain species, the spinal cord, and is also involved in gallbladder contraction and pancreatic enzyme secretion. The CCK-B/gastrin receptor is most abundant in the cerebral cortex, cerebellum, basal ganglia, and amygdala of the brain, as well as in parietal cells of the gastrointestinal tract. CCK-B receptor antagonists have been postulated to modulate anxiety, panic attacks, analgesia, and satiety (Ravard et al.,
Trends Pharmacol. Sci
., 11:271-273, 1990; Singh et al.,
Proc. Natl. Acad. Sci. U.S.A
., 88:1130-1133, 1991; Faris et al.,
Science
, 219:310-312, 1983; Dourish et al.,
Eur.J.Pharmacol
., 176:35-44, 1990; Wiertelak et al.,
Science
, 256:830-833, 1992; Dourish et al.,
Science
, 245:1509-1511, 1989).
SUMMARY OF THE INVENTION
Applicants have developed a systematic screening assay for identifying non-peptide agonists specific to peptide hormone receptors. The assay is based on applicants' recognition that a peptide hormone receptor having the capability of amplifying the intrinsic activity of a ligand is useful as a screening vehicle to identify receptor-specific agonists. In addition, a receptor with a signaling activity higher than the corresponding human wild-type basal level of signaling activity is especially useful for detecting a reduction in activity induced by an inverse agonist. In both cases, the receptor amplifies the signal generated when the ligand interacts with its receptor, relative to the signal generated when the ligand interacts with a human wild-type receptor. Thus, forms of a receptor with the ability to amplify receptor signaling are useful for efficiently screening positive and inverse non-peptide agonists to the corresponding human wild-type form of the receptor.
Accordingly, the invention features a method for determining whether a candidate compound is a non-peptide agonist of a peptide hormone receptor. In this method, a candidate compound is exposed to a form of the peptide hormone receptor which has a greater, or an enhanced, ability to amplify the intrinsic activity of a non-peptide agonist (hereafter an ‘enhanced receptor’). The second messenger signaling activity of the enhanced receptor is measured in the presence of the candidate compound, and compared to the second messenger signaling activity of the enhanced receptor measured in the absence of the candidate compound. A change in second messenger signaling activity indicates that the candidate compound is an agonist. For example, an increase in second messenger signaling activity indicates that the compound is either a full or partial positive agonist; a decrease in second messenger signaling activity indicates that the compound is an inverse (also termed a ‘negative’) agonist.
By “intrinsic activity” is meant the ability of a ligand to activate a receptor, i.e., to act as an agonist. By ‘amplify’ is meant that the signal generated when the ligand interacts with the enhanced receptor is either higher for a positive agonist, or lower for an inverse agonist, than the signal produced when the same ligand interacts with a corresponding non-enhanced receptor, e.g., a wild-type human receptor. A ‘non-enhanced receptor’, for the purposes of this invention, is a wild-type human receptor for the peptide hormone of interest. By “corresponding” is meant the same type of peptide hormone receptor albeit in another form, e.g., a constitutively active mutant receptor. By way of example, the corresponding wild-type form of a constitutively active mutant CCK-B/gastrin receptor would be a wild-type CCK-B/gastrin receptor; the human CCK-B/gastrin receptor is the corresponding human form of the rat CCK-B/gastrin receptor.
Examples of enhanced receptors include synthetic mutant receptors, e.g., constitutively active mutant receptors; other mutant receptors with normal basal activity which amplify the intrinsic activity of a compound; naturally-occurring mutant receptors, e.g., those which cause a disease phenotype by virtue of their enhanced receptor activity, e.g., a naturally-occurring constitutively active receptor; and either constitutively active or wild-type non-human receptors, e.g., rat, mouse, mastomys, Xenopus, or canine receptors or hybrid variants thereof, which amplify an agonist signal to a greater extent than does the corresponding wild-type human receptor. An enhanced receptor may, but does not always, have a higher basal activity than the basal activity of a corresponding human wild-type receptor. Methods for measuring the activity of an enhanced receptor relative to the activity of a corresponding wild-type receptor are described and demonstrated below.
Examples of peptide hormone receptors within the scope of the invention include, but are not limited to, receptors specific for the following peptide hormones: amylin, angiotensin, bombesin, bradykinin, C5a anaphylatoxin, calcitonin, calcitonin-gene related peptide (CGRP), chemokines, cholecystokinin (CCK), endothelin, follicle stimulating hormone (FSH), formyl-methionyl peptides, galanin, gastrin, gastrin releasing peptide, glucagon, glucagon-like peptide 1, glycoprotein hormones, gonadotrophin-releasing hormone, leptin, luteinizing hormone (LH), melanocortins, neuropeptide Y, neurotensin, opioid, oxytocin, parathyroid hormone, secretin, somatostatin, tachykinins, thrombin, thyrotrophin, thyrotrophin releasing hormone, vasoactive intestinal polypeptide (VIP), and vasopressin. An enhanced receptor can further embrace a single transmembrane domain peptide hormone receptor, e.g., an insulin receptor.
An “agonist”, as used herein, includes a positive agonist, e.g., a full or a partial positive agonist, or a negative agonist, i.e., an inverse agonist. An agonist is a chemical substance that combines with a receptor so as to initiate an activity of the receptor; for peptide hormone receptors, the agonist preferably alters a second messenger signaling activity. A positive agonist is a compound that enhances or increases the activity or second messenger signaling of a receptor. A “full agonist” refers to an agonist capable of activating the receptor to the maximum level of activity, e.g., a level of activity which is induced by a natural, i.e., an endogenous, peptide hormone. A “partial agonist” refers to a positive agonist with reduced intrinsic activity relative to a full agonist. As used herein, a “peptoid” is a peptide-derived partial agonist. An “inverse agonist”, as used herein, has a negative intrinsic activity, and reduces the receptor's signaling activity relative to the signaling activity measured in the absence of the inverse agonist. A diagram explaining the difference between full and partial agonists, inverse agonists, and antagonists is shown in
FIG. 1
(see also Milligan et al.,
TIPS
, 16:10-13, 1995).
Examples of peptide hormone receptor specific peptide agonists and non-peptide antagonists useful in the screening assay of the invention are described below. Non-peptide ligands include, but are not limited to, the benzodiazepines, e.g., azabicyclo[3.2.2]nonane benzodiazepine (L-740,093; Cas
Beinborn Martin
Kopin Alan S.
Clark & Elbing LLP
New England Medical Center Hospitals Inc.
Ulm John
LandOfFree
Assay for non-peptide agonists to peptide hormone receptors does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Assay for non-peptide agonists to peptide hormone receptors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Assay for non-peptide agonists to peptide hormone receptors will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2917056