(CAG)/Q expansion disorders

Details (CAG)/Q expansion disorders (CAG)/Q expansion disorders

2001-03-13

2003-04-15

Gitomer, Ralph (Department: 1651)

Chemistry: molecular biology and microbiology

Measuring or testing process involving enzymes or...

C435S006120, C435S015000

Reexamination Certificate

active

06548243

ABSTRACT:

BACKGROUND OF THE INVENTION
Huntington disease (HD) was the first disorder shown to be due to an expansion of a (CAG)
n
tract within exon 1 of the affected gene and to a resultant increase in length of a Q
n
domain within the corresponding encoded protein, huntingtin (Huntington's Disease Collaborative Research Group, “A Novel Gene Containing a Trinucleotide Repeat that is Expanded and Unstable on Huntington's Disease Chromosome,”
Cell
72:971-983 (1993)). Subsequently, seven other neurodegenerative diseases, including dentatorubral pallidoluysian atrophy, spinobulbar muscular atrophy, and spinocerebellar ataxis 1, 2, 3, 6 and 7, have been shown to be caused by pathological (CAG)
n
/Q
n
-expansions (Lunkes et al., “Polyglutamines, Nuclear Inclusions and Degenerations,”
Nat. Med
. 3:1201-1202 (1997)).
Green was the first to suggest that transglutaminase(s) may play a role in trinucleotide-repeat diseases (Green, “Human Genetic Diseases Due to Codon Reiteration: Relationship to an Evolutionary Mechanism,”
Cell
74:955-956 (1993)). Others have also suggested that transglutaminase activity may be a factor in the etiology of (CAG)
n
/Q
n
-expansion diseases (Lorand, L., “Neurodegenerative Diseases and Transglutaminase,”
Proc. Natl. Acad. Sci. USA
93:14310-14313 (1996); Cooper et al., “Polyglutamine Domains are Substrates of Tissue Transglutaminase. Does Transglutaminase Play a Role in Expanded CAG/poly-Q Neurodegenerative Diseases?,”
J. Neurochem
. 69:431-434 (1997)) and in the formation of proteinaceous deposits in the brains of Alzheimer disease patients (Selkoe et al., “Alzheimer's Diseases: Insolubility of Partially Purified Helical Filaments in Sodium Dodecyl Sulfate and Urea,”
Science
215:1243-1245 (1982) and Johnston et al., “Transglutaminase Activity is Increased in Alzheimer's Disease Brain,”
Brain Res
. 751:323-329 (1997)). In support of the idea that transglutaminases may be involved in (CAG)
n
/Q
n
-expansion diseases, Q
n
domains, whether flanked by small numbers of amino acids (Kahlem et al., “Peptides Containing Glutamine Repeats are Substrates for Transglutaminase-catalyzed Cross-linking: Relevance to Diseases of the Nervous System,”
Proc. Natl. Acad. Sci. USA
93:14580-14585 (1996) and Kahlem et al., “Transglutaminase Action Imitates Huntington's Disease: Selective Polymerization of Huntington Containing Polyglutamine,”
Mol. Cell
1:595-601 (1998)), or embedded within full-length protein constructs (Cooper et al., “Polyglutamine Domains are Substrates of Tissue Transglutaminase. Does Transglutaminase Play a Role in Expanded CAG/poly-Q Neurodegenerative Diseases?,”
J. Neurochem
. 69:431-434 (1997) and Cooper et al., “Transglutaminase-catalyzed Inactivation of Glyceraldehyde 3-Phosphate Dehydrogenase Complex by Polyglutamine Domains of Pathological Length,”
Proc. Natl. Acad. Sci. USA
94:12604-12609 (1997)), are excellent substrates of tissue transglutaminase. It has been also shown that the ability of “naked” Q
n
domains to act as Q-donor substrates of tissue transglutaminase increases in the order Q
20
<Q
40
<Q
60
(Gentile et al., “Tissue Transglutaminase-catalyzed Formation of High-Molecular-Weight Aggregates In Vitro is Favored with Long Polyglutamine Domains: A Possible Mechanism Contributing to CAG-triplet Diseases,”
Arch. Biochem. Biophys
. 352:314-321 (1998)). Moreover, the substrate activity per individual Q residue is greater for Q
60
than for Q
20
(Gentile et al., “Tissue Transglutaminase-catalyzed Formation of High-Molecular-Weight Aggregates In Vitro is Favored with Long Polyglutamine Domains: A Possible Mechanism Contributing to CAG-triplet Diseases,”
Arch. Biochem. Biophys
. 352:314-321 (1998)). Importantly, Kahlem et al. showed that huntingtin containing a pathological-length Q
n
domain is a much better substrate of commercial guinea pig liver tissue transglutaminase and of crude brain tissue transglutaminase than is huntingtin containing a non-pathological-length Q
n
domain (Kahlem et al., “Transglutaminase Action Imitates Huntington's Disease: Selective Polymerization of Huntington Containing Polyglutamine,”
Mol. Cell
1:595-601 (1998)). Thus, pathological-length Q
n
domains may be synergistically better substrates of tissue transglutaminase than are non-pathological-length Q
n
domains.
Transglutaminase activity is known to be present in both the cytosolic and nuclear fractions of a variety of cells, including brain cells (Singh et al., “Identification and Characterization of an 80 Kilodalton GTP-binding Protein/Transglutaminase from Adult Rabbit Liver Nuclei,”
Biochemistry
34:15863-15871 (1995); and Lesort et al., “Distinct Nuclear Localization and Activity of Transglutaminase,”
J. Biol. Chem
. 273:11991-11994 (1998)). These are the same compartments in which aggregates are formed in affected brain cells.
A method for diagnosing HD or a predisposition to develop HD involves determining the number of (CAG)
n
repeats present in the huntingtin gene of a patient. This method is performed by using a fragment of a nucleic acid encoding hungtingtin in a gene amplification assay or other nucleic hybridization assays. This methodology is disclosed, for example, in U.S. Pat. Nos. 5,693,757 and 5,686,288 to MacDonald et al.
However, as noted above, there are a number of (CAG)
n
/Q
n
-expansion diseases, all of which involve different genes and proteins. Diagnostic procedures using nucleic acids for one (CAG)
n
/Q
n
-expansion disease would not necessarily identify all diseases. Rather than rely on a battery of nucleic acid-based procedures to diagnose a (CAG)
n
/Q
n
-expansion disease, a single diagnostic analysis would be beneficial. In particular, it would be beneficial to obtain a quick and reliable method of diagnosing (CAG)
n
/Q
n
expansion disorders, including disease stages, and assessing the efficacy of therapeutic treatments of the (CAG)
n
/Q
n
expansion disorders. The present invention overcomes these and other deficiencies in the prior art.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to a method of diagnosing a (CAG)
n
/Q
n
-expansion disorder in an individual. This method is performed by obtaining a sample from an individual and determining whether the sample contains a concentration of N
&egr;
-(L-&ggr;-glutamyl)-L-lysine which is elevated in comparison to a normal concentration of N
&egr;
-(L-&ggr;-glutamyl)-L-lysine.
Another aspect of the present invention relates to a method of measuring progression of a (CAG)
n
/Q
n
-expansion disorder (i.e., for individuals previously diagnosed with a (CAG)
n
/Q
n
-expansion disorder). This method is performed by obtaining a first sample from an individual, determining a first concentration, of N
&egr;
-(L-&ggr;-glutamyl)-L-lysine in the first sample, obtaining a second sample from the individual at a time after the first sample is obtained, and determining a second concentration of N
&egr;
-(L-&ggr;-glutamyl)-L-lysine in the second sample. Progression of the (CAG)
n
/Q
n
-expansion disorder is indicated by the second concentration being higher than the first concentration.
Still another aspect of the present invention relates to a method of measuring therapeutic efficacy of a treatment for a (CAG)
n
/Q
n
-expansion disorder. This method is performed by obtaining a first sample from an individual, determining a first concentration of N
&egr;
-(L-&ggr;-glutamyl)-L-lysine in the first sample, providing the individual with a treatment for a (CAG)
n
/Q
n
-expansion disorder, obtaining a second sample from the individual after providing the individual with the treatment, determining a second concentration of N
&egr;
-(L-&ggr;-glutamyl)-L-lysine in the second sample, and comparing the second concentration to the first concentration to measure the therapeutic efficacy of the treatment for a (CAG)
n
/Q
n
-expansion disorder.
As indicated previously, there are currently a number of diseases or disorders that have been classified as (CAG)
n
/Q
n
-expansion disorders, particularly neurodegenerative diseases. Each

Affiliated with

Also associated with

Rating

(CAG)/Q expansion disorders does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with (CAG)/Q expansion disorders, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and (CAG)/Q expansion disorders will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3059125