title: Identification of novel Kirrel3 gene splice variants in adult human skeletal muscle.
abstract: BACKGROUND
  Multiple cell types including trophoblasts, osteoclasts and myoblasts require somatic cell fusion events as part of their physiological functions. In Drosophila Melanogaster the paralogus type 1 transmembrane receptors and members of the immunoglobulin superfamily Kin of Irre (Kirre) and roughest (Rst) regulate myoblast fusion during embryonic development. Present within the human genome are three homologs to Kirre termed Kin of Irre like (Kirrel) 1, 2 and 3. Currently it is unknown if Kirrel3 is expressed in adult human skeletal muscle.
  
  
  RESULTS
  We investigated (using PCR and Western blot) Kirrel3 in adult human skeletal muscle samples taken at rest and after mild exercise induced muscle damage. Kirrel3 mRNA expression was verified by sequencing and protein presence via blotting with 2 different anti-Kirrel3 protein antibodies. Evidence for three alternatively spliced Kirrel3 mRNA transcripts in adult human skeletal muscle was obtained. Kirrel3 mRNA in adult human skeletal muscle was detected at low or moderate levels, or not at all. This sporadic expression suggests that Kirrel3 is expressed in a pulsatile manner. Several anti Kirrel3 immunoreactive proteins were detected in all adult human skeletal muscle samples analysed and results suggest the presence of different isoforms or posttranslational modification, or both.
  
  
  CONCLUSIONS
  The results presented here demonstrate for the first time that there are at least 3 splice variants of Kirrel3 expressed in adult human skeletal muscle, two of which have never previously been identified in human muscle. Importantly, mRNA of all splice variants was not always present, a finding with potential physiological relevance. These initial discoveries highlight the need for more molecular and functional studies to understand the role of Kirrel3 in human skeletal muscle.
authors.affiliation: Department of Physiological Science, Stellenbosch University, Private Bag X1 Matieland, 7602, Stellenbosch, South Africa. pdurcan@sun.ac.za.
authors.forename: Peter Joseph
authors.initials: PJ
authors.lastname: Durcan
authors.affiliation: Department of Physiological Science, Stellenbosch University, Private Bag X1 Matieland, 7602, Stellenbosch, South Africa. 15476324@sun.ac.za.
authors.forename: Johannes D
authors.initials: JD
authors.lastname: Conradie
authors.affiliation: Division of Endocrinology, Department of Medicine, Stellenbosch University, Tygerberg, South Africa. vandevyverm@sun.ac.za.
authors.forename: Mari
authors.initials: M
authors.lastname: Van deVyver
authors.affiliation: Department of Physiological Science, Stellenbosch University, Private Bag X1 Matieland, 7602, Stellenbosch, South Africa. khm@sun.ac.za.
authors.forename: Kathryn Helen
authors.initials: KH
authors.lastname: Myburgh
mesh_terms: D000293:Adolescent; D000328:Adult; D002352:Carrier Proteins / Q000378:metabolism*; D015444:Exercise; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D055815:Young Adult
chemical_list: D002352:Carrier Proteins; C470936:KIRREL3 protein, human; D008565:Membrane Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger