Thesis (M.S.)--University of Michigan, 2003. / Includes bibliographical references.

The transforming growth factor (TGF)-β superfamily mediates a wide range of differentiation and developmental processes across many genera. GDF9 and BMP15 are expressed exclusively in the mammalian ovary and are the only TGF-β ligands that lack the conserved cysteine residue used for dimerisation. As a platform for studying the interactions between GDF9 and BMP15 and their receptors, BMPRII and BMPRIb, a variety of strategies were attempted to produce soluble and active proteins from recombinant systems. Both ligands and receptors showed a tendency to form insoluble aggregates when expressed in prokaryotic systems; however after extensive screening, quantities of biologically active GDF9 were produced using in vitro refolding. When expressed alone, either containing a histidine tag or as an untagged protein, the BMPRII ectodomain was deposited as insoluble inclusion bodies. This protein, subjected to in vitro refolding procedures, exhibited multiple species following anion exchange chromatography and size exclusion chromatography, as visualised on native PAGE. Separation of these species could be achieved using a MonoP matrix. One of these separated fractions, representing about 5% of the starting material, was amenable to crystallisation, and furthermore exhibited activity in a rat granulosa cell thymidine incorporation assay. Two different crystals forms of the extracellular domain of BMPRII were grown from the same protein batch under similar crystallisation conditions. Notably, the tetragonal form that grew more slowly possessed several disordered finger regions, while electron density for the entire molecule was clear in the orthorhombic form. The hydrophobic core of the ligand binding surface of BMPRII , as seen in both structures, resembles that of ActRII bound to BMP2. The A-loop of BMPRII, which is involved in ligand binding, lies in two different conformations in the two structures of BMPRII, mediated by a rearrangement in disulfide Cys94-Cys117. It is proposed here that the tetragonal form represents the ligand-bound receptor structure. Although the majority of the hydrophobic binding surface is shared with ActRII(b), it is likely that His87 and Tyr40 are unique residues that confer specificity in BMPRII ligand binding.

Thesis (M. Med. Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 71-84).

During development of the nervous system, signals from specialized organizing centers generate distinct cell types. The signaling molecule, Sonic Hedgehog (SHH) is expressed by the floor plate (FP) and is sufficient to specify the ventral midbrain pattern. In the spinal cord, Bone Morphogenetic Proteins (BMPs) expressed in the roof plate (RP) specify dorsal cell-fates. The attenuation of BMP signaling is required for SHHmediated patterning of the ventral hindbrain and spinal cord, while BMP signaling is required in conjunction with SHH for ventral forebrain patterning. This thesis will focus on the function of SHH and BMPs in the midbrain by examining the molecules ability to pattern and regulate development. Midbrains of Shh[superscript -/-] mice were examined. Some ventral cell fates are specified in the Shh[superscript -/-] mouse in a Ptc1 and Gli1 independent manner. Ventral midbrain induction was observed to be Hh-independent by the existence of a Pax7-negative ventral midbrain territory before embryonic day 9. Interestingly, dorsal markers are not uniformly altered and increased cell death was seen in Shh[superscript -/-] dorsal midbrains. These results suggest specific regulation of dorsal patterning by Shh, rather than a simple deregulation. Several BMPs and their antagonists are expressed in a spatial and temporal manner in the midbrain. Expression of BMPs is seen in the RP, and rostral FP (rFP), which also expresses SHH. BMP signaling was manipulated using in vivo electroporation. NOGGIN misexpression resulted in a loss of RP and a reduction of dorsal cell-fates that was preceded by cell-shape changes, delamination of cells into the lumen and their elimination. This was accompanied by a reduction and alteration of midbrain size and shape. BMP blockade changed N-Cadherin distribution and perturbed pseudostratified morphology of the neurepithelium. Ventrally, BMP blockade resulted in a decrease of proliferation, while increasing differentiation, Notch signaling molecules at the rFP and medial FP markers. However ventral midbrain cell-fates were correctly specified. Notch-Delta signaling was examined in the Mib[superscript -/-] mouse. Different regulation of cell-fates was observed in the midbrain and spinal cord. Mib[superscript -/-] midbrains lacked a mature lateral FP, however ventral cell-fates are specified. Mib[superscript -/-] spinal cords lose Shh expression and several ventral cell-fates. / text

M. Tech. Pharmaceutical Sciences. / Xenogeneic collagen has previously been reported to be a poor delivery system for bone morphogenetic proteins, because of its immunogenic effects in the host. In the laboratory the researcher uses, the problems associated with the xenogeneic bone matrix has been overcome by chemical swelling employing acetic acid followed by pepsin digestion to reduce telopeptides. This has improved host biocompatibility. The central focus of the current study was to improve the performance of the previously developed delivery system by employing a combination of BMP-2 and TGF-ß1 in a rat heterotopic assay.

No description available.

Recombinant human bone morphogenetic proteins (rhBMPs) are increasingly used for reconstructing bony defects, fracture non-unions, and augmenting existing bone volumes. For the numerous patients taking bisphosphonates, the impact of prior bisphosphonate treatment on rhBMP bone induction is not well understood. Objective: to evaluate the effect of the prior treatment with zoledronate on rhBMP induced bone formation in mice. Methods: 42 mice were pre-treated with 0, 2, and 20 µg of zoledronate/mouse. The osteoinductive activity of a bioimplant, containing rhBMP-2, was assessed using the mouse muscle pouch assay, and analyzed with micro CT and histology. Results: micro CT demonstrated that BMP bioimplants placed in mice pretreated with 20 µg of zoledronate, formed bony ossicles of greater volume but reduced bone density compared to controls. Histologically, the heterotopic ossicles from the 20 µg group consisted of more immature bone than those from the other groups. Conclusion: bone induced by rhBMP-2 in mice pre-treated with a high concentration of zoledronate was immature as evidenced by radiographic and histologic appearance.

Recombinant human bone morphogenetic proteins (rhBMPs) are increasingly used for reconstructing bony defects, fracture non-unions, and augmenting existing bone volumes. For the numerous patients taking bisphosphonates, the impact of prior bisphosphonate treatment on rhBMP bone induction is not well understood. Objective: to evaluate the effect of the prior treatment with zoledronate on rhBMP induced bone formation in mice. Methods: 42 mice were pre-treated with 0, 2, and 20 µg of zoledronate/mouse. The osteoinductive activity of a bioimplant, containing rhBMP-2, was assessed using the mouse muscle pouch assay, and analyzed with micro CT and histology. Results: micro CT demonstrated that BMP bioimplants placed in mice pretreated with 20 µg of zoledronate, formed bony ossicles of greater volume but reduced bone density compared to controls. Histologically, the heterotopic ossicles from the 20 µg group consisted of more immature bone than those from the other groups. Conclusion: bone induced by rhBMP-2 in mice pre-treated with a high concentration of zoledronate was immature as evidenced by radiographic and histologic appearance.

No description available.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 4 uppsatser.