Genome-Wide Identification, Characterization and Expression Analysis of the Solute Carrier 6 Gene Family in Silkworm (Bombyx mori).

Xin Tang,Quanmei Chen,Ping Zhao,Huawei Liu,Xin Wang,Ying Xiong

doi:10.3390/ijms17101675

Xin Tang, Quanmei Chen + Show 4 more

Open Access

https://doi.org/10.3390/ijms17101675

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Abstract

The solute carrier 6 (SLC6) gene family, initially known as the neurotransmitter transporters, plays vital roles in the regulation of neurotransmitter signaling, nutrient absorption and motor behavior. In this study, a total of 16 candidate genes were identified as SLC6 family gene homologs in the silkworm (Bombyx mori) genome. Spatio-temporal expression patterns of silkworm SLC6 gene transcripts indicated that these genes were highly and specifically expressed in midgut, brain and gonads; moreover, these genes were expressed primarily at the feeding stage or adult stage. Levels of expression for most midgut-specific and midgut-enriched gene transcripts were down-regulated after starvation but up-regulated after re-feeding. In addition, we observed that expression levels of these genes except for BmSLC6-15 and BmGT1 were markedly up-regulated by a juvenile hormone analog. Moreover, brain-enriched genes showed differential expression patterns during wandering and mating processes, suggesting that these genes may be involved in modulating wandering and mating behaviors. Our results improve our understanding of the expression patterns and potential physiological functions of the SLC6 gene family, and provide valuable information for the comprehensive functional analysis of the SLC6 gene family.

Highlights

The solute carrier 6 (SLC6) gene family of membrane transporters shuttle extracellular neurotransmitters, amino acids and osmolytes across the plasma membrane into the cytoplasm through co-transport of Na+ and Cl−
To identify all SLC6 transporter homologs in the silkworm genome, we performed a BLASTP search against the NCBI GenBank and the Silkworm Genome Database (SilkDB) using known SLC6 protein sequences from other species
A total of 16 transporters were identified in the silkworm genome, including two previously identified SLC6 genes, namely BmDAT and BmSERT (Table 1)

Summary

Introduction

The solute carrier 6 (SLC6) gene family of membrane transporters shuttle extracellular neurotransmitters, amino acids and osmolytes across the plasma membrane into the cytoplasm through co-transport of Na+ and Cl−. The amino acid transporters (II) subfamily, which accepts a broad spectrum of substrates, differs from the other aforementioned transporters in physiological function. This particular subfamily is involved in the neutral amino acid absorption and play important roles in various metabolic processes [11,12,13]. A GABA transporter controls GABA homeostasis and plays an important role in anxiety disorders [17] These results suggested that NTTs are involved in various physiological processes, such as locomotor activity, anxiety behaviors, and stress behaviors [18,19,20,21]. Our results will further enhance studies of the evolution and function of SLC6 genes in insects

Results

Phylogenetic Analysis of the Insect SLC6 Family Members

Insect Rearing and Sample Collection

Phylogenetic Tree Construction