Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or...
Reexamination Certificate
2000-09-25
2003-11-25
Yucel, Remy (Department: 1636)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
C435S006120, C435S007100, C435S455000, C435S320100, C435S377000, C536S023100, C536S023200, C536S024100
Reexamination Certificate
active
06653064
ABSTRACT:
The present invention relates to the therapy of bone disorders associated with reduced bone mass.
Bone formation, the synthesis and deposition of extracellular matrix, is essential for skeletal growth, modeling, remodeling and repair. Osteoblasts, the bone-forming cell type of the skeleton, originate from pluripotent mesenchymal stem cells. The differentiation and proliferation of osteoblasts can be modulated by numerous extracellular factors such as hormones, growth factors and cytokines. Recently, the transcription factor Cbfa-1 was found to be essential for osteoblast differentiation (Banerjee, et al., 1997; Ducy, et al., 1997; Otto, et al., 1997; Komori, et al., 1997). However, the molecular mechanisms which control bone formation in vivo are poorly understood.
Activator protein-1 (AP-1) is a dimeric transcription factor composed of Jun, Fos or ATF (activating transcription factor) family members. AP-1 binds to a common DNA site, the AP-1 binding site, and converts extracellular signals into changes in the transcription of many cellular and viral genes (reviewed in Angel and Karin, 1991). AP-1 activity is modulated by various signals including growth factors, cytokines, tumor promoters, carcinogens and specific oncogenes. AP-1 has been implicated in a number of biological processes such as cell proliferation, cell differentiation and apoptosis. However, analysis of AP-1 functions in vivo and in tissue culture cells have shown that different AP-1 members regulate different target genes and thus execute distinct biological functions in a cell-type specific fashion.
Several lines of evidence suggest that AP-1 participates in the control of osteoblast functions. Consensus AP-1 DNA binding sites are present in the promoter regions of genes involved in the regulation of osteoblast growth, differentiation, and extracellular matrix formation and degradation, such as alkaline phosphatase, type I collagen, osteocalcin, osteopontin, and matrix metalloproteases-1 and -13 (Owen, et al., 1990; Schule, et al., 1990; Guo, et al., 1995; Angel, et al., 1987; Pendas, et al., 1997). A number of regulators of osteoblast proliferation and differentiation, including transforming growth factor-&bgr; (TGF-&bgr;), parathyroid hormone, growth hormone and 1,25-dihydroxyvitamin D, induce the expression of AP-1 components in vitro and in vivo in osteoblastic cells (Candeliere, et al., 1991; Slootweg, et al., 1991; Clohisy, et al., 1992; Machwate, et al., 1995; Koe, et al., 1997). Moreover, the various components of the AP-1 complex are differentially expressed during osteoblast differentiation in vitro and can be detected at sites of active bone formation in vivo (Dony and Gruss, 1987; Sandberg, et al., 1988; Smeyne, et al., 1992; McCabe, et al., 1995; McCabe, et al., 1996).
Fra-1 is an immediate early gene encoding one member of the AP-1 family of transcription factors which shows extensive amino acid homology to c-Fos (Cohen and Curran, 1988). Fra-1 forms heterodimeric complexes with all Jun proteins (c-Jun, junB, junD) and interacts with AP-1 binding sites to regulate gene transcription (Cohen, et al., 1989; Ryseck and Bravo, 1991; Suzuki, et al., 1991). Unlike c-Fos, Fra-1 lacks a C-terminal transactivation domain (Wisdom and Verma, 1993). In addition to induction by serum and mitogens, Fra-1 expression is regulated upon lymphocyte activation and during the differentiation of keratinocytes, spermatocytes and osteoblasts (McCabe, et al., 1995; McCabe, et al., 1996; Cohen and Curran, 1988; Cohen, et al., 1993; Welter and Eckert, 1995; Gandarillas and Watt, 1995; Huo and Rothstein, 1996; Rutberg, et al., 1996). Moreover, ectopic expression of Fra-1 in osteoclast progenitor cell lines potentiates osteoclast development (Owens, et al., 1999).
Reduced bone mass, either circumscribed or systemic, results in impaired bone strength and predisposes to pathological fractures.
Common causes of localized osteolytic lesions are metastatic bone disease, multiple myeloma and lymphoma. In addition, circumscribed bone defects can be caused by numerous benign bone disorders including, among others, bone cysts, fibrous dyslasia, infections, benign bone tumors and impaired fracture healing. Current treatment of these lesions comprises surgical removal or radiotherapeutic destruction of the pathological tissue, fracture fixation, implant stabilization and the reconstruction of the skeletal defect. However, current surgical methods utilizing autograft or allograft bone to close the skeletal defects have limitations. Autograft procedures can result in donor site fracture and donor-site pain, and are limited by the amount of autogenous bone available. Allograft is biologically inactive in the host and has immunological and infectious disease risks.
In contrast, osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration in the entire skeleton with a consequent increase in bone fragility and susceptibility to fracture, especially of bones subjected to major mechanical forces.
Bone is remodeled throughout life, involving the coordinate occurence of bone resorption and bone formation. Osteoporosis develops if the rate of bone resorption exceeds the rate of bone formation resulting in a progressive loss of bone mass. A large number of risk factors for osteoporosis have been identified including aging and loss of gonadal function. In addition, osteoporosis is associated with various endocrine, haematologic, gastrointestinal and rheumatologic diseases, and can be the consequence of therapy with glucocorticoids, heparin, and antiepileptic drugs. The major clinical manifestation of osteoporosis are vertebral body fractures, leading to pain in the back and deformity of the spine. The diagnosis of osteoporosis is based on reduced bone mass, usually assessed by measuring bone mineral density. Most of the drugs used to treat osteoporosis act by decreasing bone resorption, including estrogens, bisphosphonates, and calcitonin. Therapeutic regimens which effectively stimulate bone formation are not available. Although sodium fluoride therapy results in large increases in bone mineral density, its effect on fracture rates is small, since it stimulates the formation of a bone matrix with low mechanical strength.
It was the object of the present invention to provide an improved therapy to restore the mechanical properties of affected bone(s) by enhancing bone formation, either locally or in the entire skeleton, in individuals suffering from bone disorders that are associated with a circumscribed or systemic reduction of bone tissue.
In order to provide a therapeutic approach based on the administration of drugs that are capable of stimulating bone formation, the cellular and molecular mechanisms underlying bone formation were studied.
In order to study the consequences of ectopic Fra-1 expression in vivo, transgenic mice were generated which express high levels of Fra-1 in a broad range of tissues, including bone. It was shown that ectopic Fra-1 expression stimulates bone formation by osteoblasts leading to the development of increased bone mass in the entire skeleton. Furthermore, the data obtained in the experiments of the present invention indicate that constitutive Fra-1 expression promotes osteoblast proliferation and differentiation, since transgenic bones contain increased numbers of mature osteoblasts. Moreover, osteoblastic cells derived from transgenic mice were shown to undergo an accelerated course of differentiation in vitro indicating that Fra-1 can positively regulate bone formation in vivo and in vitro.
Maintenance of bone mass depends on the balance between bone formation by osteoblasts and bone resorption by osteoclasts. In the majority of mouse models of increased bone mass reported on to date, impairment of bone resorption is causal, due to defects either in osteoclast differentiation or function, resulting in osteopetrosis (Johnson, et al., 1992; Wang, et al., 1992; Grigoriadis, et al., 1994; Iotsova, et al., 1997; Simonet, et al., 1997; Tondravi, et al., 1997; Saftig, et al.,
David Jean-Pierre
Jochum Wolfram
Matsuo Koichi
Wagner Erwin F.
Boehringer Ingelheim International GmbH
Nguyen Quang
Sterne Kessler Goldstein & Fox PLLC
Yucel Remy
LandOfFree
Method for identifying compounds useful in the therapy of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for identifying compounds useful in the therapy of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for identifying compounds useful in the therapy of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3171538