Cloning and characterization of a human adenylyl cyclase

Details Cloning and characterization of a human adenylyl cyclase Cloning and characterization of a human adenylyl cyclase

1999-12-29

2002-04-16

Prouty, Rebecca E. (Department: 1652)

Chemistry: molecular biology and microbiology

Enzyme , proenzyme; compositions thereof; process for...

Lyase

C435S069100, C435S183000, C435S252300, C435S320100, C435S325000, C435S369000, C536S023200

Reexamination Certificate

active

06372475

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to DNA encoding a human adenylyl cyclase. This invention also relates to the adenylyl cyclase encoded by that DNA. Referred to herein as the human type IX adenylyl cyclase (hAC9) polypeptide, this enzyme can be used as a tool to screen for agonists and antagonists that can either stimulate or inhibit type IX adenylyl cyclase activity. Such compounds have therapeutic utility in treating (1) diseases that are caused by aberrant activity of this enzyme and (2) diseases whose symptoms can be ameliorated by stimulating or inhibiting the activity of type IX adenylyl cyclase. The present invention also relates to the isolated entire human gene encoding the human type IX adenylyl cyclase, methods for the recombinant production of purified human type IX adenylyl cyclase and the proteins made by these methods, antibodies against the whole human type IX adenylyl cyclase or regions thereof, vectors, nucleotide probes, and host cells transformed by genes encoding polypeptides having human type IX adenylyl cyclase activity, along with diagnostic and therapeutic uses for these various reagents.
BACKGROUND OF THE INVENTION
Adenylyl cyclases direct the intracellular synthesis of the primary second messenger, cyclic-3′,5′-adenosine monophosphate (cAMP), by converting ATP to cAMP, principally in response to a diverse family of membrane spanning, G-protein coupled receptors, each activated by its own extracellular hormone or protease. Signal transduction for G-protein coupled receptors occurs through a coupled heterotrimeric G protein complex composed of the alpha (G
&agr;
), and beta/gamma (G
&bgr;&ggr;
) subunits. Upon receptor stimulation, G
&agr;
exchanges GTP for GDP, dissociates from both G
&bgr;&ggr;
and the receptor, and proceeds to directly regulate various effectors, including adenylyl cyclase. Multiple families of G
&agr;
proteins have been identified, two of which are named for their effects on regulating adenylyl cyclase activity (G
&bgr;s
family stimulates all adenylyl cyclases, while G
&agr;i
family inhibits most but not all of the adenylyl cyclases). Each of these G
&agr;
proteins has its own tissue distribution, and subset of coupled receptors, which favors receptor specific regulation of adenylyl cyclase.
Additional studies have suggested other means by which adenylyl cyclase activity may be regulated within tissues. This concept is derived from findings that a number of adenylyl cyclase isoforms exist, each with their own gene locus, distinct set of responses to intracellular signals and unique tissue distribution. To date, nine separate isoforms (Types I-IX) have been characterized, principally from rodents, each with its own regulatory properties and tissue specific distribution.
The structure of adenylyl cyclases has been greatly studied and the putative domains given standard nomenclature. Topographically, the adenylyl cyclase isoforms are similar, having two six-transmembrane spanning regions associated with an intracellular N-terminus, a large cytoplasmic loop (ICD III, more commonly referred to as “C
1
”) and a large intracellular C-terminus (more commonly referred to as “C
2
”). The transmembrane region between the N-terminus and the C
1
loop is commonly referred to as “M1”. The M1 region has three extracellular domains (ECD I, II and III), two intracellular domains (ICD I and II) and six transmembrane domains (TM I, II, III, IV, V and VI). The region between the C
1
loop and the C-terminus is referred to as “M2”. The M2 region has three extracellular domains (ECD IV, V and VI), two intracellular domains (ICD IV and V) and six transmembrane domains (TM VII, VIII, IX, X, XI and XII). The N-terminus is commonly divided into two regions, designated “N
1
” and “N
2
”. The large C
1
cytoplasmic loop is also divided into two regions, a long “C
1a
” region and a shorter “C
1b
” region. Lastly, the C-terminus is divided into a long “C
2a
” region and a shorter “C
2b
” region. An extensive discussion of these regions can be found in Broach, et al., WO 95/30012, which is incorporated herein by reference. The amino acid sequence of the C
1a
and C
2a
regions are conserved among the different isoforms. On the other hand, the N-terminus, C
1b
and C
2b
regions show the most diversity among the various isoforms.
Based on sequence and functional similarities, these isoforms fall into six distinct classes of adenylyl cyclases. Types IV and VI have a wide tissue distribution. However, Type IX is in a class of its own, being the most divergent of the isoforms and having a ubiquitous tissue distribution.
Diversity in activities, and differences in distribution and prevalence of adenylyl cyclase isoforms, may contribute to tissue specific regulation of cAMP levels. It is expected that by taking advantage of distinct structural and biochemnical differences between different adenylyl cyclases, isoform specific or selective modulators can be discovered. This, in conjunction with knowledge of the proportion and distribution of each isoform in select tissues provides a means by which one can develop either tissue specific, or selective pharmacological agents since it is expected that isoform specific modulators would have tissue specificity related to the distribution of that isoform.
Key to the development of selective pharmacological agents is information pertaining to the tissue specific distribution and prevalence of each isoform. To date most of this information is available for isoform mRNA levels in a handful of non-human mammals, although some select mRNA (e.g. Type V) have been measured for many human tissues. Acquiring information on protein isoform distribution in human tissues is considered an important aspect of pharmaceutical research in this area, since this could either strengthen existing target information or point to different isoforms, when compared with mRNA data.
To date, only three full length human adenylyl cyclase isoforms have been cloned: Type II adenylyl cyclase (Stengel, et al., Hum. Genet. 90:126-130 (1992)), Type VII adenylyl cyclase (Nomura, et al., DNA Research 1:27-35 (1994)) and Type VIII adenylyl cyclase (Defer, et al., FEBS Letters 351:109-113 (1994)).
Type IX, first cloned from mouse brain, is in a unique isoform class, being the most divergent of the isoforms and having a wide tissue distribution. Premont, et al. Jour. Biol. Chem. 271(23):13900-13907 (1996). The human isoform has not been cloned until now.
SUMMARY OF THE INVENTION
One aspect of the invention is an isolated and purified human type IX adenylyl cyclase (hAC9) polypeptide comprising the amino acid sequence of
FIG. 2
(SEQ ID NO:2).
Another aspect of the invention is an isolated and purified nucleic acid encoding for the hAC9 polypeptide.
Yet another aspect of the invention is an isolated and purified nucleic acid comprising the nucleotide sequence of
FIG. 2
(SEQ ID NO:1), which encodes a biologically active hAC9 polypeptide, or fragment thereof.
Still another aspect of the invention is an isolated and purified nucleic acid comprising the nucleotide sequence of
FIG. 2
(SEQ ID NO:1), which encodes a biologically active soluble hAC9 peptide fragment.
Another aspect of the present invention also relates to the human gene encoding human type IX adenylyl cyclase, which has both diagnostic and therapeutic uses as are described below. Included within this invention are proteins or peptides having substantial homology with proteins or peptides comprising the amino acid sequence of
FIG. 2
or encoded by a gene having substantial homology with the nucleotide sequence of
FIG. 2
, and which exhibit the same characteristics of human type IX adenylyl cyclase.
Yet another aspect of the invention is a method of producing hAC9 which comprises incorporating a nucleic acid having the nucleotide sequence of
FIG. 2
(SEQ ID NO:1) into an expression vector, transforming a host cell with the vector and culturing the transformed host cell under conditions which result in expression of the gene.


REFERENCES:
patent: WO95/30012 (1995-09-01),

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