Porcine SLITRK1: Molecular cloning and characterization

Abstract

The membrane protein SLITRK1 functions as a developmentally regulated stimulator of neurite outgrowth and variants in this gene have been implicated in Tourette syndrome. In the current study we have cloned and characterized the porcine SLITRK1 gene. The genomic organization of SLITRK1 lacks introns, as does its human and mouse counterparts. RT-PCR cloning revealed two SLITRK1 transcripts: a full-length mRNA and a transcript variant that results in a truncated protein. The encoded SLITRK1 protein, consisting of 695 amino acids, displays a very high homology to human SLITRK1 (99%). The porcine SLITRK1 gene is expressed exclusively in brain tissues.

Keywords: ADHD, attention deficit hyperactivity disorder; DNA methylation; LRR, leucine-rich repeats; OCD, obsessive–compulsive disorder; Pig; SLITRK1; TS, Tourette syndrome; Tourette.

Fig. 1

Schematic presentation of the SLITRK1 protein. In the extracellular domain, SLITRKs contains two leucine-rich repeat (LRR) domains, which are each composed of 13–17 LRRs, flanked by cysteine-rich domains. The characteristic domains of SLITRK1 are indicated by their respective names: SP, signal peptide; LRR, leucine-rich repeat; LRR-CT, LRR C-terminal domain; TMR, transmembrane region.

Fig. 2

Alignment of amino acid sequences of the porcine SLITRK1 protein (GenBank Access. No. KJ210858) with SLITRK1 sequences from human (NM_052910) and mouse (NM_199065). Sequence alignment was performed using the Clustal W program at Kyoto University Bioinformatics Center (http://www.genome.jp/tools/clustalw). The numbers represent the positions of the amino acids in the respective protein sequences. Identical amino acids in all three sequences are indicated by asterisks. The following abbreviations for species names are used: Ss, Sus scrofa; Hs, Homo sapiens; Mm, Mus musculus.

Fig. 3

Splice variant of porcine SLITRK1. Amino acid sequence alignment of porcine SLITRK1 (wt) and a splice variant, SLITRK1-Sp1, hereof. (A). The SLITRK1-Sp1 encodes a truncated version of the full length protein.

Fig. 4

Expression of porcine SLITRK1 mRNA determined by RNAseq. Relative abundance of SLITRK1 is reported in FPKM units. The tissues presented are: occipital cortex (OCC), frontal cortex (FCO), cerebellum (CBE), hypothalamus (HYP), heart (HEA), lung (LUN), musculus longissimus dorsi (LDO), liver (LIV), kidney (KID) and spleen (SPL). The error bars represent the biological variation between the two animals employed.