Bone mineralization proteins, DNA, vectors, expression systems

Details Bone mineralization proteins, DNA, vectors, expression systems Bone mineralization proteins, DNA, vectors, expression systems

1998-07-29

2001-10-09

Clark, Deborah J. R. (Department: 1633)

Chemistry: molecular biology and microbiology

Animal cell, per se ; composition thereof; process of...

C435S320100, C435S455000, C536S023100, C536S023500

Reexamination Certificate

active

06300127

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention relates generally to osteogenic cells and the formation of bone and boney tissue in mammalian species. Specifically, the invention concerns a novel family of proteins, and nucleic acids encoding those proteins, that enhances the efficacy of bone mineralization in vitro and in vivo. The invention provides methods for treating a variety of pathological conditions associated bone and boney tissue, such as, for example, spine fusion, fracture repair and osteoporosis.
2. Description of the Related Art
Osteoblasts are thought to differentiate from pluripotent mesenchymal stem cells. The maturation of an osteoblast results in the secretion of an extracellular matrix which can mineralize and form bone. The regulation of this complex process is not well understood but is thought to involve a group of signaling glycoproteins known as bone morphogenetic proteins (BMPs). These proteins have been shown to be involved with embryonic dorsal-ventral patterning, limb bud development, and fracture repair in adult animals. B. L. Hogan,
Genes
&
Develop
., 10:1580 (1996). This group of transforming growth factor-beta superfamily secreted proteins has a spectrum of activities in a variety of cell types at different stages of differentiation; differences in physiological activity between these closely related molecules have not been clarified. D. M. Kingsley,
Trends Genet
., 10:16 (1994).
To better discern the unique physiological role of different BMP signaling proteins, we recently compared the potency of BMP-6 with that of BMP-2 and BMP-4, for inducing rat calvarial osteoblast differentiation. Boden et al.,
Endocrinology
, 137:3401 (1996). We studied this process in first passage (secondary) cultures of fetal rat calvaria that require BMP or glucocorticoid for initiation of differentiation. In this model of membranous bone formation, glucocorticoid (GC) or a BMP will initiate differentiation to mineralized bone nodules capable of secreting osteocalcin, the osteoblast-specific protein. This secondary culture system is distinct from primary rat osteoblast cultures which undergo spontaneous differentiation. In this secondary system, glucocorticoid resulted in a ten-fold induction of BMP-6 mRNA and protein expression which was responsible for the enhancement of osteoblast differentiation. Boden et al.,
Endocrinology
, 138:2920 (1997).
In addition to extracellular signals, such as the BMPs, intracellular signals or regulatory molecules may also play a role in the cascade of events leading to formation of new bone. One broad class of intracellular regulatory molecules are the LIM proteins, which are so named because they possess a characteristic structural motif known as the LIM domain. The LIM domain is a cysteine-rich structural motif composed of two special zinc fingers that are joined by a 2-amino acid spacer. Some proteins have only LIM domains, while others contain a variety of additional functional domains. LIM proteins form a diverse group, which includes transcription factors and cytoskeletal proteins. The primary role of LIM domains appears to be in mediating protein-protein interactions, through the formation of dimers with identical or different LIM domains, or by binding distinct proteins.
In LIM homeodomain proteins, that is, proteins having both LIM domains and a homeodomain sequence, the LIM domains function as negative regulatory elements. LIM homeodomain proteins are involved in the control of cell lineage determination and the regulation of differentiation, although LIM-only proteins may have similar roles. LIM-only proteins are also implicated in the control of cell proliferation since several genes encoding such proteins are associated with oncogenic chromosome translocations.
Humans and other mammalian species are prone to diseases or injuries that require the processes of bone repair and/or regeneration. For example, treatment of fractures would be improved by new treatment regimens that could stimulate the natural bone repair mechanisms, thereby reducing the time required for the fractured bone to heal. In another example, individuals afflicted with systemic bone disorders, such as osteoporosis, would benefit from treatment regimens that would results in systemic formation of new bone. Such treatment regimens would reduce the incidence of fractures arising from the loss of bone mass that is a characteristic of this disease.
For at least these reasons, extracellular factors, such as the BMPs, have been investigated for the purpose of using them to stimulate formation of new bone in vivo. Despite the early successes achieved with BMPs and other extracellular signalling molecules, their use entails a number of disadvantages. For example, relatively large doses of purified BMPs are required to enhance the production of new bone, thereby increasing the expense of such treatment methods. Furthermore, extracellular proteins are susceptible to degradation following their introduction into a host animal. In addition, because they are typically immunogenic, the possibility of stimulating an immune response to the administered proteins is ever present.
Due to such concerns, it would be desirable to have available treatment regimens that use an intracellular signalling molecule to induce new bone formation. Advances in the field of gene therapy now make it possible to introduce into osteogenic precursor cells, that is, cells involved in bone formation, nucleotide fragments encoding intracellular signals that form part of the bone formation process. Gene therapy for bone formation offers a number of potential advantages: (1) lower production costs; (2) greater efficacy, compared to extracellular treatment regiments, due to the ability to achieve prolonged expression of the intracellular signal; (3) it would by-pass the possibility that treatment with extracellular signals might be hampered due to the presence of limiting numbers of receptors for those signals; (4) it permits the delivery of transfected potential osteoprogenitor cells directly to the site where localized bone formation is required; and (5) it would permit systemic bone formation, thereby providing a treatment regimen for osteoporosis and other metabolic bone diseases.
SUMMARY OF THE INVENTION
The present invention seeks to overcome the drawbacks in the prior art by providing novels compositions and methods for inducing bone formation using an intracellular signalling molecule that participates early in the cascade of events that leads to bone formation. Applicants have discovered 10-4/RLMP (SEQ ID NO: 1, SEQ ID NO: 2), a novel LIM gene with a sequence originally isolated from stimulated rat calvarial osteoblast cultures. The gene has been cloned, sequenced and assayed for its ability to enhance the efficacy of bone mineralization in vitro. The protein RLMP affects mineralization of bone matrix as well as differentiation of cells into the osteoblast lineage. Unlike other known cytokines, for example, BMPs, RLMP is not a secreted protein, but is instead an intracellular signaling molecule. This feature has the advantage of providing intracellular signaling amplification as well as easier assessment of transfected cells. It is also suitable for more efficient and specific in vivo applications. Suitable clinical applications include enhancement of bone repair in fractures, bone defects, bone grafting, and normal homeostasis in patients presenting with osteoporosis.
Applicants have also cloned, sequenced and deduced the amino acid sequence of a corresponding human protein, named human LMP-1. The human protein demonstrates enhanced efficacy of bone mineralization in vitro and in vivo.
In addition, the applicants have characterized a truncated (short) version of LMP-1, termed HLMP-1s. This short version resulted from a point mutation in one source of a cDNA clone, providing a stop codon which truncated the protein. The short version (LMP-1s) is fully functional when expressed in cell culture and in vivo.
Additional features and advantages of the

Affiliated with

Also associated with

Rating

Bone mineralization proteins, DNA, vectors, expression systems does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Bone mineralization proteins, DNA, vectors, expression systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bone mineralization proteins, DNA, vectors, expression systems will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2571354