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Distinct spatial and temporal expression patterns of two type I receptors for bone morphogenetic proteins during
N Dewulf1, K Verschueren, O Lonnoy
1Laboratory of Molecular Biology (CELGEN), University of Leuven, Belgium.
Endocrinology
|June 1, 1995
Summary
Bone morphogenetic proteins (BMPs) signal through type I receptors like ALK-3 and ALK-6. These receptors are crucial for bone and cartilage development, with broader roles in embryonic development.
Area of Science:
- Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Bone morphogenetic proteins (BMPs) are key regulators of cartilage and bone growth.
- BMPs signal through heteromeric serine/threonine kinase receptor complexes (Type I and Type II).
- Six type I receptors, activin receptor-like kinases (ALKs) 1-6, have been identified, with specific roles in TGF-beta superfamily signaling.
Purpose of the Study:
- To clone the mouse homolog of ALK-3 and investigate the expression patterns of ALK-3 and ALK-6 during mouse embryonic development.
- To elucidate the roles of ALK-3 and ALK-6 in embryonic development and their potential as BMP receptors.
Main Methods:
- Complementary DNA (cDNA) cloning of the mouse ALK-3 homolog.
- Analysis of ALK-3 and ALK-6 messenger RNA (mRNA) distribution in adult mouse tissues using Northern blot or similar techniques.
- In situ hybridization to determine the spatial and temporal expression of ALK-3 and ALK-6 mRNA in postimplantation mouse embryos (6.5-15.5 days postcoitum).
Main Results:
- The mouse ALK-3 homolog was cloned and found to be highly conserved between mouse and human.
- ALK-3 mRNA was ubiquitously expressed in adult mouse tissues, except for the liver.
- ALK-6 mRNA was restricted to brain and lung in adults.
- During embryonic development, ALK-3 mRNA was widely expressed, with notable absence in the liver.
- ALK-6 mRNA expression began at 9.5 days postcoitum and persisted until 15.5 days postcoitum, with transcripts found in developing cartilage, muscle, blood vessels, central nervous system, sensory organs, and epithelium.
Conclusions:
- The expression patterns of ALK-3 and ALK-6 in developing cartilage and bone support their roles as in vivo receptors for BMPs.
- The widespread expression of ALK-3 and ALK-6 in various embryonic soft tissues suggests broader functions for BMPs beyond skeletal development.
- These findings highlight the importance of ALK-3 and ALK-6 in both skeletal and soft tissue embryogenesis.