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Modulation of WNT-5A expression by actinonin: linkage of APN to the WNT-pathway?
U Lendeckel1, M Arndt, K Frank
1Institute of Experimental Internal Medicine, Otto-von-Guericke University Magdeburg, Germany.
Abstract:
Inhibition of alanyl-aminopeptidase gene expression or enzymatic activity compromises T cell proliferation and function. Molecular mechanisms mediating these effects are not known as yet. Applying the cDNA array technique we identified the proto-oncogen Wnt-5a strongly affected by APN-inhibition. Wnt-5a and other members of the Wnt family of secreted factors are implicated in cell growth and differentiation. Wnt-5a was moderately expressed in resting T cells, but strongly down-regulated in response to activation by OKT3/IL-4/IL-9. Actinonin increased Wnt-5a-mRNA contents as confirmed by RT-PCR. In addition, expression of GSK-3 beta, an inherent component of the Wnt-pathway, was found to be increased in response to activation, but suppressed by actinonin at both the mRNA and protein level. These findings may provide a rationale for the strong growth inhibitory effects resulting from an inhibition of alanyl aminopeptidase expression or activity.
Insights
Inhibiting alanyl aminopeptidase (APN) disrupts T cell function. This study reveals APN inhibition upregulates Wnt-5a and downregulates GSK-3 beta, explaining T cell growth inhibition.
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- Alanyl aminopeptidase (APN) is crucial for T cell proliferation and function.
- The molecular mechanisms underlying APN's role in T cells remain unclear.
- Understanding these mechanisms is vital for T cell-mediated immunity research.
Purpose of the Study:
- To elucidate the molecular mechanisms by which alanyl aminopeptidase (APN) inhibition affects T cell function.
- To identify key molecular players involved in APN-mediated T cell regulation.
- To investigate the impact of APN inhibition on Wnt signaling pathways in T cells.
Main Methods:
- Utilized cDNA array technique to identify genes affected by APN inhibition.
- Employed Reverse Transcription Polymerase Chain Reaction (RT-PCR) to validate gene expression changes.
- Analyzed protein and mRNA levels of Wnt-5a and GSK-3 beta.
Main Results:
- APN inhibition strongly affected the proto-oncogene Wnt-5a expression.
- Wnt-5a mRNA levels were increased by actinonin, an APN inhibitor.
- GSK-3 beta, a Wnt-pathway component, showed increased expression upon activation but was suppressed by actinonin at both mRNA and protein levels.
- Wnt-5a was down-regulated upon T cell activation but upregulated by APN inhibition.
Conclusions:
- APN inhibition leads to significant alterations in Wnt-5a and GSK-3 beta expression in T cells.
- These molecular changes provide a potential explanation for the observed T cell growth inhibition.
- Findings highlight a novel role for APN in regulating T cell function via Wnt signaling.