title: BMP4-induced differentiation of a rat spermatogonial stem cell line causes changes in its cell adhesion properties.
abstract: Spermatogonial stem cells (SSCs) are at the basis of the spermatogenic process and are essential for the continuous lifelong production of spermatozoa. Although several factors that govern SSC self-renewal and differentiation have been investigated, the direct effect of such factors on SSCs has not yet been studied, mainly because of the absence of markers to identify SSCs and the lack of effective methods to obtain and culture a pure population of SSCs. We now have used a previously established rat SSC cell line (GC-6spg) to elucidate the role of BMP4 in SSC differentiation. We found that GC-6spg cells cultured in the presence of BMP4 upregulate KIT expression, which is an early marker for differentiating spermatogonia. GC-6spg cells were found to express three BMP4 receptors and the downstream SMAD1/5/8 proteins were phosphorylated during BMP4-induced differentiation. A time-course DNA micro-array analysis revealed a total of 529 differentially regulated transcripts (≥2-fold), including several known downstream targets of BMP4 such as Id2 and Gata2. Pathway analysis revealed that the most affected pathways were those involved in adherens junctions, focal junctions, gap junctions, cell adhesion molecules, and regulation of actin cytoskeleton. Interestingly, among the genes belonging to the most strongly affected adhesion pathways was Cdh1 (known as E-cadherin), an adhesion molecule known to be expressed by a subpopulation of spermatogonia including SSCs. Overall, our results suggest that BMP4 induces early differentiation of SSCs in a direct manner by affecting cell adhesion pathways.
authors.affiliation: Center for Reproductive Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Carlomagno
authors.forename: Maaike P A
authors.initials: MP
authors.lastname: van Bragt
authors.forename: Cindy M
authors.initials: CM
authors.lastname: Korver
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Repping
authors.forename: Dirk G
authors.initials: DG
authors.lastname: de Rooij
authors.forename: Ans M M
authors.initials: AM
authors.lastname: van Pelt
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000502:physiology*; D052004:Bone Morphogenetic Protein Receptors / Q000378:metabolism; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D013091:Spermatogenesis; D013093:Spermatogonia / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism
chemical_list: D000943:Antigens, Differentiation; C525811:Bmp4 protein, rat; D055415:Bone Morphogenetic Protein 4; D015820:Cadherins; D015815:Cell Adhesion Molecules; D012333:RNA, Messenger; D019009:Proto-Oncogene Proteins c-kit; D052004:Bone Morphogenetic Protein Receptors