Poster abstracts
Poster number 160 submitted by Emily Slobodenyuk
Three genes, one protein: Investigating 3'UTR-driven mRNA localization and protein function of the calmodulin gene family
Emily Slobodenyuk (Cellular and Molecular Biology, University of Michigan), Brittany Bowman (Biological Chemistry, University of Michigan), Chase Weidmann (Biological Chemistry, University of Michigan)
Abstract:
Calmodulin (CaM) is an essential, highly conserved, ubiquitously expressed calcium-binding protein, and interacts with many proteins to regulate a myriad of cellular functions, including the cell cycle, cell motility, neurotransmitter release, and the cardiac action potential. Interestingly, in mammals, three divergent CaM genes at separate genomic loci encode an identical calmodulin protein. Notably, the protein-coding regions of Calm1, Calm2, Calm3 mRNA within species are as minimally similar as possible while encoding the same protein. This suggests that while enough time has passed for their sequences to diverge, natural selection has retained three separate CaM genes that encode the same protein sequence.
The individual Calm genes behave as though they are functionally distinct. For example, the Calm mRNAs are expressed at different levels in different tissues and exhibit unique subcellular localization patterns in neurons and cardiomyocytes. Identical mutations to the protein-coding sequence in each gene induce different disease phenotypes. Further, Calm mRNA 3′UTRs (untranslated regions) are extremely different between the three genes yet are among the most highly conserved UTR sequences between the species. Since 3'UTRs are critical for regulating mRNA stability and localization, we expect that 3′UTR cis-regulatory elements drive the differential localization of the Calm transcripts and determine the distinct functions of each gene’s expressed CaM protein.
Through a combination of RNA FISH reporter assays, endogenous epitope tagging, and affinity selection mass spectrometry, we aim to understand how 3′UTR elements control the behavior of Calm mRNAs and the different encoded CaM protein interaction networks and functions. I have begun by identifying Calm mRNA isoform distributions within rat neuronal cells using short and long-read sequencing. Neuronal cells provide a model for tracking differential localization of Calm mRNA and encoded protein in distinct cellular locales.
References:
Villalobo, et al. Int J Mol Sci, 2020
Wu et al., Int J Mol Sci, 2021
Munk et al., Cell Calcium, 2022
Innan et al., Nat Rev Genet, 2010
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Toutenhoofd, et al., Cell Calcium, 2000
Fischer et al., J Biol Chem, 1988
Mayr, Cold Spring Harb Perspect Biol, 2019
Keywords: mRNA localization, mRNA regulation, sequencing