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Osteocalcin is incompletely spliced in non-osseous tissues
1Molecular Urology and Therapeutics Program, Department of Urology, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA.
Gene
|June 22, 2001
Summary
Osteocalcin (OC) expression is regulated by RNA splicing, not just promoters. Incompletely spliced OC mRNA variants are found in non-osseous tissues, unlike bone marrow which shows complete splicing.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Osteocalcin (OC) is recognized as a bone-specific protein.
- Its expression is traditionally attributed to promoter control.
Purpose of the Study:
- To investigate the role of RNA splicing in tissue-specific Osteocalcin (OC) expression.
- To identify and characterize incompletely spliced OC mRNA variants in various human tissues.
Main Methods:
- Northern blot analysis to detect OC RNA transcripts.
- RT-PCR and sequence analysis to identify OC mRNA variants.
- In situ hybridization and immunohistochemistry to localize OC RNA and protein.
Main Results:
- Two main OC RNA transcripts were identified, with varying expression levels across tissues.
- Non-osseous tissues predominantly expressed higher molecular weight transcripts, indicating incomplete splicing.
- Up to six OC transcripts, including intron-retaining variants, were found in most tissues except bone marrow.
- Prostate tumor cells showed dominant incompletely spliced OC RNA with low protein levels.
Conclusions:
- Osteocalcin (OC) expression is regulated at the RNA splicing level, in addition to promoter control.
- Bone marrow exhibits preferential complete splicing of all three OC introns.
- The functions of various incompletely spliced OC mRNA variants in non-osseous tissues require further investigation.