Evolutionary analyses reveal independent origins of gene repertoires and structural motifs associated to fast inactivation in calcium-selective TRPV channels

Lisandra Flores-Aldama,Sebastian E Brauchi,Juan C Opazo,Michael W Vandewege,Wendy Gonzalez,Charlotte K Colenso,Kattina Zavala

doi:10.1038/s41598-020-65679-6

Abstract

Essential for calcium homeostasis, TRPV5 and TRPV6 are calcium-selective channels belonging to the transient receptor potential (TRP) gene family. In this study, we investigated the evolutionary history of these channels to add an evolutionary context to the already available physiological information. Phylogenetic analyses revealed that paralogs found in mammals, sauropsids, amphibians, and chondrichthyes, are the product of independent duplication events in the ancestor of each group. Within amniotes, we identified a traceable signature of three amino acids located at the amino-terminal intracellular region. The signature correlates with both the duplication events and the phenotype of fast inactivation observed in mammalian TRPV6 channels. Electrophysiological recordings and mutagenesis revealed that the signature sequence modulates the phenotype of fast inactivation in all clades of vertebrates but reptiles. A transcriptome analysis showed a change in tissue expression from gills, in marine vertebrates, to kidneys in terrestrial vertebrates. Our results highlight a cytoplasmatic structural triad composed by the Helix-Loop-Helix domain, the S2-S3 linker, and the TRP domain helix that is important on modulating the activity of calcium-selective TRPV channels.

Highlights

Essential for calcium homeostasis, TRPV5 and TRPV6 are calcium-selective channels belonging to the transient receptor potential (TRP) gene family
The differences between the TRPV1–4 and TRPV5–6 clades can be traced to specific regions, including the ankyrin repeat domain (ARD), the Helix-loop-Helix domain (HLH), the intracellular linker between transmembrane segments 2 and 3 (S2–S3), and the pore domain (PD) (Supplementary Figure 1)
Genes encoding TRPV5 and TRPV6 channels are located in a conserved genomic region, flanked by EPHB6 and KEL, suggesting that this genomic location was present early in vertebrate evolution and has remained relatively well conserved (Fig. 1; Supplementary Figure 2)

Summary

Introduction

Essential for calcium homeostasis, TRPV5 and TRPV6 are calcium-selective channels belonging to the transient receptor potential (TRP) gene family. TRPV5 and TRPV6 are calcium-selective ion channel members of the Transient Receptor Potential (TRP) gene family[3] These proteins, expressed at the apical membrane of Ca2+ transporting epithelia, serve as entry channels in transepithelial Ca2+ transport[3]. It has been suggested that mammalian TRPV5 and TRPV6 channels originated from a duplication event in the last common ancestor of the group, between 312 and 177 million years ago[9,10]. This would suggest that these genes belong to the mammalian clade exclusively and are not orthologs to TRPV5 and TRPV6 channels of other vertebrate groups Besides these observations, not much else is known about the evolutionary history of these channels in vertebrates. Thorough phylogenetic analyses in combination with functional assays allowed us to explore their evolutionary history and the evolution of functional features

Methods

Results

Conclusion