Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues
Reexamination Certificate
1998-12-09
2001-05-22
Ulm, John (Department: 1646)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
C514S002600
Reexamination Certificate
active
06235880
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to nucleic acid and amino acid sequences of a novel human sulfonylurea receptor and to the use of these sequences in the diagnosis, study, prevention and treatment of disease.
BACKGROUND OF THE INVENTION
ATP-dependent potassium (K
ATP
) channels serve to couple metabolic state to electrical activity in many types of cells. By hyperpolarizing the cell, K
ATP
channels limit electrical activity and hence reduce Ca
2+
entry into muscle and nerve cells. In the pancreas, they are a critical link between blood glucose concentration and insulin secretion.
Sulfonylureas (SUs) are oral hypoglycemics widely used in the treatment of non-insulin dependent diabetes mellitus (NIDDM). SUs stimulate insulin release from pancreatic islet &agr; cells. The mechanism for insulin release involves 1) inhibition of a K
ATP
channel which sets the &bgr; cell resting membrane potential, 2) reduction of K
+
outflow which causes &bgr; cell depolarization and 3) the activation of one or more voltage-dependent L-type calcium channels which results in Ca
2+
influx, exocytosis, and insulin release. SUs such as tolbutamide or glyburide decrease K
ATP
channel activity, thereby depolarizing the cell and triggering insulin release.
Until recently the K
ATP
channel and the sulfonylurea receptor (SUR) were thought to be the same molecule (Aguilar-Bryan et al (1995) Science 268:423-426); however, SUR does not possess intrinsic K
+
channel activity (Ammala C et al (1996) Nature 379:545-548). Instead SUR interacts with inward-rectifier K
+
channels, conferring SU and ATP sensitivity to and modulating the activity of these channels (Inagaki N et al (1995) Science 270: 1166-1170).
A second isoform of SUR, denoted SUR2, has recently been discovered in rat. This isoform has different tissue distribution and different SU and ATP binding properties from rat SUR (Inagaki N et al (1996) Neuron 16:1011-1017). The channel kinetics of Kir6.2, an inward-rectifier K
+
channel, co-expressed with SUR2 are different than the channel kinetics of Kir6.2 co-expressed with SUR. Based on these observations, it is suggested that a family of structurally related but functionally distinct SURs determine the ATP sensitivity and pharmacological responses of KAT, channels in various tissues (Inagaki N et al (1996), supra).
SURs from rat and hamster consist of 1581 and 1582 amino acids, respectively, with 12 potential membrane-spanning helices (Aguilar-Bryan et al, supra). In addition, the proteins contain two domains having strong similarity to the nucleotide binding folds (NBFs) of the ATP-binding cassette (ABC) superfamily of proteins. The proposed topology of the rat, hamster, and a recently reported human SUR (GenBank GI 1369844; unpublished) consists of an external amino terminus, nine predicted transmembrane helices, the first cytosolic NBF (NBF-1), four more transmembrane helices, the second cytosolic NBF (NBF-2) and a cytosolic C-terminus. The topology of the SURs are similar to other members of the ABC superfamily including multidrug resistance (MDR) proteins and cystic fibrosis transmembrane regulators (CFTR; Philipson LH and Steiner DF (1995) Science 268:372-373).
Ad The NBFs of ABC superfamily proteins control activity through their interaction with cytosolic nucleotides. In cystic fibrosis, the more frequent and severe disease mutations are located in the nucleotides encoding the two NBFs of the CFTR protein (Tsui L-C (1992) Trends Genet 8:392). Familial persistent hyperinsulinemic hypoglycemia of infancy (PHHI) may be caused by mutations affecting NBF-2 of SUR (Thomas PM et al (1995) Science 268:426-429).
SU-sensitive K
ATP
channels are present in brain cells and play a role in neurosecretion at nerve terminals. K
ATP
channels in the substantia nigra, a brain region that shows high SU binding, are inhibited by high glucose concentrations and antidiabetic SUs, and are activated by ATP depletion and anoxia. Furthermore, inhibition of the KAT, channel activates gamma-aminobutyric acid (GABA) release, whereas K
ATP
channel activation inhibits GABA release (Amoroso S et al (1990) Science 247:852-854; Schmidt-Antomarchi et al (1990) Proc Natl Acad Sci USA 87: 3489-3492).
Action potentials in cardiac cells are modulated by SU compounds binding to SURs. The duration of the action potential of guinea pig cardiac cells was drastically reduced by decreasing intracellular ATP concentrations ([ATP]
in
) by perfusion or by blockade of oxidative phosphorylation. Glibenclamide, an SU compound, was found to restore normal or nearly normal action potentials in these [ATP]
in
-depleted cardiac cells. (Fosset M et al (1988) J Biol Chem 263:7933-7936). Restoration was attributed to inhibition of cardiac K
ATP
channels by sulfonylurea compounds acting via the SURs.
SURs confer ATP and SU sensitivity to inwardly-rectifying potassium channels, thereby coupling metabolic state to electrical activity in tissues such as brain, pancreas, and heart. SURs are useful in the diagnosis and treatment of diseases related to abnormal K
ATP
channel function, such as NIDDM and PHHI. The selective modulation of the expression or activities of SURs may allow the successful management of such diseases.
SUMMARY OF THE INVENTION
The present invention discloses a human sulfonylurea receptor protein, hereinafter referred to as SURH, having chemical and structural homology to the SUR protein from rat and hamster. Accordingly, the invention features a substantially purified SURH, having the amino acid sequence of SEQ ID NO:1 and the structural characteristics of SURs.
One aspect of the invention features isolated and substantially purified polynucleotides which encode SURH. In a particular aspect, the polynucleotide is the nucleotide sequence of SEQ ID NO:2. In another aspect, the polynucleotide is the nucleotide sequence extending from T
2780
to A
2923
of SEQ ID NO:2.
The invention also relates to a polynucleotide sequence comprising the complement of SEQ ID NO:2 or variants thereof. In addition, the invention features nucleotide sequences which hybridize under stringent conditions to SEQ ID NO:2.
The present invention also relates to an expression vector which contains polynucleotides encoding SURH, and the use of said vector to transform or transfect host cells or organisms. The invention also features methods for producing SURH. The present invention also relates to antibodies which bind specifically to SURH polypeptides, and to agonists and antagonists of SURH. The present invention also relates to pharmaceutical compositions comprising SURH, fragments thereof, agonists of SURH, or antagonists of SURH, in conjunction with a suitable pharmaceutical carrier.
REFERENCES:
patent: WO 95/28411 (1995-10-01), None
Aguilar-Bryan et al. Cloning of the beta Cell High-Affinity Sulfonylurea Receptor: A Regulator of Insulin Secretion. Science 268:423-426, Apr. 1995.*
Atassi. Preparation of Monoclonal Antibodies to Preselected Protein Regions. Methods in Enzymology 121:69-95, 1986.*
Aguilar-Bryan, et al., “Cloning of the &bgr; Cell High-Affinity Sulfonylurea Receptor: A Regulator of Insulin Secretion, ”Science, 268:423-426 (1995).
Inagaki, N., et al., “Recognition of Ikatp: An Inward Rectifier Subunit Plus the Sulfonylurea Receptor”Science, 270:1166-1170 (1995).
Inagaki, N., et al., “A Family of Sulfonylurea Receptors Determines the Pharmacological Properties of ATP-Sensitive K+ Channels”Neuron, 16:1011-1017 (1996).
Gonzalez, G., et al., (GI 1369844), GenBank Sequence Database (Accession 1369844), National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894 1998).
Philipson, L.H., et al., “Pas de Deux or More: The Sulfonylurea Receptor and K+Channels”Science, 268:372-373 (1995).
Tsui, L.C., “The spectrum of cystic fibrosis mutations”Trends Genet., 8:392 (1992).
Thomas, P.M., et al., “Mutations in the Sulfonylurea Receptor Gene in Familial Persistent Hyperinsulinemic Hypoglycemia of Infancy”Science, 268:426-429 (1995
Au-Young Janice
Bandman Olga
Coleman Roger
Incyte Genomics, Inc.
Incyte Pharmaceuticals Inc.
Murry Lynn E.
Ulm John
LandOfFree
Human sulfonylurea receptor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Human sulfonylurea receptor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Human sulfonylurea receptor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2543475