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Partial Inhibition of Calcineurin Activity by Rcn2 as a Potential Remedy for Vps13 Deficiency
Patrycja Wardaszka1, Piotr Soczewka1, Marzena Sienko1
1Institute of Biochemistry and Biophysics Polish Academy of Science, 02-106 Warsaw, Poland.
Abstract:
Regulation of calcineurin, a Ca2+/calmodulin-regulated phosphatase, is important for the nervous system, and its abnormal activity is associated with various pathologies, including neurodegenerative disorders. In yeast cells lacking the VPS13 gene (vps13Δ), a model of VPS13-linked neurological diseases, we recently demonstrated that calcineurin is activated, and its downregulation reduces the negative effects associated with vps13Δ mutation. Here, we show that overexpression of the RCN2 gene, which encodes a negative regulator of calcineurin, is beneficial for vps13Δ cells. We studied the molecular mechanism underlying this effect through site-directed mutagenesis of RCN2. The interaction of the resulting Rcn2 variants with a MAPK kinase, Slt2, and subunits of calcineurin was tested. We show that Rcn2 binds preferentially to Cmp2, one of two alternative catalytic subunits of calcineurin, and partially inhibits calcineurin. Rcn2 ability to bind to and reduce the activity of calcineurin was important for the suppression. The binding of Rcn2 to Cmp2 requires two motifs in Rcn2: the previously characterized C-terminal motif and a new N-terminal motif that was discovered in this study. Altogether, our findings can help to better understand calcineurin regulation and to develop new therapeutic strategies against neurodegenerative diseases based on modulation of the activity of selected calcineurin isoforms.
Insights
Overexpressing RCN2 benefits yeast with VPS13 mutations by inhibiting calcineurin. This study identifies new RCN2 motifs essential for binding calcineurin subunit Cmp2, offering therapeutic insights for neurodegenerative diseases.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Calcineurin, a Ca2+/calmodulin-regulated phosphatase, is crucial for nervous system function.
- Dysregulated calcineurin activity is linked to neurodegenerative disorders.
- Yeast lacking VPS13 (vps13Δ) models VPS13-linked neurological diseases, exhibiting activated calcineurin.
Purpose of the Study:
- To investigate the beneficial effects of RCN2 gene overexpression in vps13Δ yeast cells.
- To elucidate the molecular mechanism by which RCN2 regulates calcineurin activity.
- To identify novel regulatory motifs within RCN2.
Main Methods:
- Site-directed mutagenesis of the RCN2 gene.
- Assays to test the interaction of Rcn2 variants with calcineurin subunits and MAPK kinase Slt2.
- Functional analysis of Rcn2's inhibitory effect on calcineurin activity.
Main Results:
- Overexpression of RCN2 is beneficial for vps13Δ yeast cells.
- Rcn2 preferentially binds to the Cmp2 subunit of calcineurin, partially inhibiting its activity.
- Rcn2 binding to Cmp2 requires both a known C-terminal motif and a newly discovered N-terminal motif.
Conclusions:
- Rcn2's ability to bind and inhibit calcineurin is critical for suppressing vps13Δ phenotypes.
- The identified RCN2 motifs are essential for its interaction with Cmp2.
- Findings advance understanding of calcineurin regulation and suggest therapeutic strategies for neurodegenerative diseases via calcineurin isoform modulation.
