title: Transcriptome profiling of mice testes following low dose irradiation.
abstract: BACKGROUND
  Radiotherapy is used routinely to treat testicular cancer. Testicular cells vary in radio-sensitivity and the aim of this study was to investigate cellular and molecular changes caused by low dose irradiation of mice testis and to identify transcripts from different cell types in the adult testis.
  
  
  METHODS
  Transcriptome profiling was performed on total RNA from testes sampled at various time points (n = 17) after 1 Gy of irradiation. Transcripts displaying large overall expression changes during the time series, but small expression changes between neighbouring time points were selected for further analysis. These transcripts were separated into clusters and their cellular origin was determined. Immunohistochemistry and in silico quantification was further used to study cellular changes post-irradiation (pi).
  
  
  RESULTS
  We identified a subset of transcripts (n = 988) where changes in expression pi can be explained by changes in cellularity. We separated the transcripts into five unique clusters that we associated with spermatogonia, spermatocytes, early spermatids, late spermatids and somatic cells, respectively. Transcripts in the somatic cell cluster showed large changes in expression pi, mainly caused by changes in cellularity. Further investigations revealed that the low dose irradiation seemed to cause Leydig cell hyperplasia, which contributed to the detected expression changes in the somatic cell cluster.
  
  
  CONCLUSIONS
  The five clusters represent gene expression in distinct cell types of the adult testis. We observed large expression changes in the somatic cell profile, which mainly could be attributed to changes in cellularity, but hyperplasia of Leydig cells may also play a role. We speculate that the possible hyperplasia may be caused by lower testosterone production and inadequate inhibin signalling due to missing germ cells.
authors.forename: Kirstine C
authors.initials: KC
authors.lastname: Belling
authors.forename: Masami
authors.initials: M
authors.lastname: Tanaka
authors.forename: Marlene Danner
authors.initials: MD
authors.lastname: Dalgaard
authors.forename: John Erik
authors.initials: JE
authors.lastname: Nielsen
authors.forename: Henrik Bjørn
authors.initials: HB
authors.lastname: Nielsen
authors.forename: Søren
authors.initials: S
authors.lastname: Brunak
authors.forename: Kristian
authors.initials: K
authors.lastname: Almstrup
authors.forename: Henrik
authors.initials: H
authors.lastname: Leffers
mesh_terms: D000465:Algorithms; D000818:Animals; D020869:Gene Expression Profiling; D007985:Leydig Cells / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D046228:Microarray Analysis; D012708:Sertoli Cells / Q000378:metabolism / Q000528:radiation effects; D013087:Spermatids / Q000378:metabolism / Q000528:radiation effects; D013090:Spermatocytes / Q000378:metabolism / Q000528:radiation effects; D013093:Spermatogonia / Q000378:metabolism / Q000528:radiation effects; D013737:Testis / Q000378:metabolism* / Q000528:radiation effects*; D059467:Transcriptome / Q000235:genetics*; D014965:X-Rays