1. Identification of a novel leptin receptor duplicate in Atlantic salmon: Expression analyses in different life stages and in response to feeding status.
- Author
-
Angotzi, Anna R., Stefansson, Sigurd O., Nilsen, Tom O., Øvrebø, Jan.I., Andersson, Eva, Taranger, Geir L., and Rønnestad, Ivar
- Subjects
- *
ATLANTIC salmon , *FISH feeds , *LEPTIN receptors , *CHROMOSOME duplication , *BIOLOGICAL evolution , *REPRODUCTION - Abstract
In recent years rapidly growing research has led to identification of several fish leptin orthologs and numerous duplicated paralogs possibly arisen from the third and fourth round whole genome duplication (3R and 4R WGD) events. In this study we identify in Atlantic salmon a duplicated LepRA gene, named LepRA 2 , that further extend possible evolutionary scenarios of the leptin and leptin receptor system. The 1121 amino acid sequence of the novel LepRA 2 shares 80% sequence identity with the LepRA 1 paralog, and contains the protein motifs typical of the functional (long form) leptin receptor in vertebrates. In silico predictions showed similar electrostatic properties of LepRA 1 and LepRA 2 and high sequence conservation at the leptin interaction surfaces within the CHR/leptin-binding and FNIII domains, suggesting conserved functional specificity between the two duplicates. Analysis of temporal expression profiles during pre-hatching stages indicate that both transcripts are involved in modulating leptin developmental functions, although the LepRA 1 paralog may play a major role as the embryo complexity increases. There is ubiquitous distribution of LepRs underlying pleiotropism of leptin in all tissues investigated. LepRA 1 and LepRA 2 are differentially expressed with LepRA 1 more abundant than LepRA 2 in most of the tissues investigated, with the only exception of liver. Analysis of constitutive LepRA 1 and LepRA 2 expression in brain and liver at parr, post-smolt and adult stages reveal striking spatial divergence between the duplicates at all stages investigated. This suggests that, beside increased metabolic requirements, leptin sensitivity in the salmon brain might be linked to important variables such as habitat, ecology and life cycle. Furthermore, leptins and LepRs mRNAs in the brain showed gene-specific variability in response to long term fasting, suggesting that leptin’s roles as modulator of nutritional status in Atlantic salmon might be governed by distinct genetic evolutionary processes and distinct functions between the paralogs. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF