Transcriptional profiling validates involvement of extracellular matrix and proteinases genes in mouse gonad development

Extracellular matrix (ECM) plays an important scaffolding role in the establishment of organs structure during development. A great number of ECM components and enzymes (proteinases) regulating formation/degradation of ECM during organ remodeling have been identified. In order to study the role of ECM in the mouse gonad development, especially during sexual differentiation of the gonads when the structure of the testis and ovary becomes established, we performed a global analysis of transcriptome in three main cell types of developing gonad (supporting, interstitial/stromal and germ cells) using transgenic mice, cell sorting and microarray. The genes coding for ECM components were mostly expressed in two gonadal cell lines: supporting and interstitial/stromal cells. These two cell lines differed in the expression pattern of ECM components, which suggests that ECM components might be crucial for differentiation of gonad compartments (for example testis cords vs. interstitium in XY gonads). Collagens and proteoglycans coding genes were mainly expressed in the interstitium/stromal cells, while non-collagen glycoproteins and matricellular coding genes were expressed in both cell lines. We also analyzed the expression of genes encoding ECM enzymes that are secreted to the ECM where they remodel the scaffolding of developing organs. We found that the ECM enzyme genes were also mostly expressed in supporting and interstitial/stromal cells. In contrast to the somatic cells, the germ cells expressed only limited number of ECM components and enzymes. This suggests that the germ line cells do not participate, or play only a minor role, in the sculpting of the gonad structure via ECM synthesis and remodeling. Importantly, the supporting cells showed the sex-specific pattern of expression of ECM components. However, the pattern of expression of most ECM enzymes in the somatic and germ cells is independent on the sex of the gonad. Further studies are required to elucidate the exact roles of identified genes in sexual differentiation of the gonads.