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Purification and molecular cloning of a novel group of BMPs and localization of BMP mRNA in developing bone
V Rosen1, J M Wozney, E A Wang
1Genetics Institute, Inc., Cambridge, MA 02140.
Abstract:
Using a novel purification scheme, we have characterized BMP as a 30kD fraction. After reduction, which destroys biological activity, this fraction was shown to be comprised of individual polypeptides with molecular weights of 30kD, 18kD and 16kD. Molecular cloning of these polypeptides resulted in the identification of 4 previously undescribed genes (BMP-1, BMP-2A, BMP-2B, and BMP-3) each of which is capable of directing de novo cartilage formation in vivo. While BMP-1 appears to be unrelated to other known growth factors, the derived amino acid sequence of BMP-2A, 2B, and 3 indicate that they are new members of the TGFb gene family. BMP-1, 2A and 2B are expressed in rat embryos during morphogenesis and can be localized by in situ hybridization to developing limb buds. BMP-3 localizes to neural ectoderm and later on in development to newly forming periosteum. Comparisons to other members of the TGFb family suggest that these newly identified BMPs are involved in pattern formation during early skeletal development.
Insights
Researchers identified four new bone morphogenetic protein (BMP) genes. These genes direct new cartilage formation and are crucial for skeletal development in rat embryos.
Area of Science:
- Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Bone morphogenetic proteins (BMPs) are critical signaling molecules in skeletal development.
- Previous characterization of BMPs was limited, necessitating further investigation into their composition and genetic basis.
Purpose of the Study:
- To purify and characterize the active components of BMP.
- To identify the genes encoding these components and determine their relationship to known growth factors.
- To investigate the expression patterns and developmental roles of newly identified BMPs.
Main Methods:
- Novel purification techniques to isolate BMP fractions.
- Protein reduction and molecular weight analysis (SDS-PAGE).
- Molecular cloning and sequencing of identified polypeptides.
- In situ hybridization for gene expression localization in embryonic tissues.
Main Results:
- A 30kD BMP fraction was purified, dissociating into 30kD, 18kD, and 16kD polypeptides after reduction.
- Four novel genes (BMP-1, BMP-2A, BMP-2B, BMP-3) were identified.
- BMP-2A, BMP-2B, and BMP-3 are new members of the TGF-beta gene family.
- BMP-1, 2A, and 2B are expressed in developing limb buds during rat embryogenesis.
- BMP-3 is localized to neural ectoderm and developing periosteum.
Conclusions:
- The identified BMPs are capable of inducing de novo cartilage formation.
- BMP-1, 2A, 2B, and 3 play significant roles in early skeletal pattern formation.
- These findings expand the known BMP family and highlight their importance in embryonic development.