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Identification of cyclic AMP-phosphodiesterase variants from the PDE4D gene expressed in human peripheral mononuclear
1Department of Gynecology and Obstetrics, Stanford University School of Medicine, CA 94305, USA.
Abstract:
To determine whether the expression of different PDE4D variants is unique to the rat or conserved through evolution, we have characterized the different PDE4D mRNAs expressed in human peripheral blood mononuclear cells. RT-PCR was performed using primers based on rat sequences and mRNAs from mononuclear cells. The specifically amplified fragments had a size identical to that predicted for rat PDE4D1, PDE4D2 and PDE4D3. Sequencing confirmed that these fragments are derived from the human PDE4D gene. Their sequence was highly homologous to that reported for the rat variants. cDNAs corresponding to the entire ORF of human PDE4D2 and PDE4D3 were expressed in mammalian cells, causing a large increase in PDE activity. Western blot analysis of human peripheral blood mononuclear cell extracts demonstrated the presence of proteins corresponding to the recombinant PDE4D1 and PDE4D2. The pattern of splicing and different promoter usage of the PDE4D gene is therefore conserved during evolution, which indicates an important physiological role.
Insights
The study found that phosphodiesterase 4D (PDE4D) gene expression patterns, including splicing and promoter usage, are conserved across species, suggesting a vital physiological role for PDE4D variants.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Phosphodiesterase 4D (PDE4D) is a crucial enzyme involved in various cellular processes.
- Understanding the evolutionary conservation of PDE4D variants can provide insights into its physiological significance.
Purpose of the Study:
- To investigate whether the expression of different PDE4D variants is unique to rats or conserved in humans.
- To characterize the PDE4D mRNA variants present in human peripheral blood mononuclear cells.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) using rat-derived sequences on human mononuclear cell mRNA.
- DNA sequencing to confirm the identity and homology of amplified human PDE4D fragments.
- Expression of human PDE4D2 and PDE4D3 in mammalian cells and Western blot analysis of human cell extracts.
Main Results:
- RT-PCR successfully amplified human PDE4D mRNA fragments homologous to rat PDE4D1, PDE4D2, and PDE4D3.
- Sequencing confirmed these fragments originate from the human PDE4D gene.
- Expressed human PDE4D2 and PDE4D3 increased phosphodiesterase activity, and PDE4D1 and PDE4D2 proteins were detected in human cells.
Conclusions:
- The splicing patterns and promoter usage of the PDE4D gene are conserved between rats and humans.
- This evolutionary conservation suggests a critical and conserved physiological role for PDE4D variants.