Multipotent adult germline stem cells and embryonic stem cells have similar microRNA profiles

Spermatogonial stem cells (SSCs) isolated from the adult mouse testis and cultured have been shown to respond to culture conditions and become pluripotent, so called multipotent adult germline stem cells (maGSCs). microRNAs (miRNAs) belonging to the 290 and 302 miRNA clusters have been previously classified as embryonic stem cell (ESC) specific. Here, we show that these miRNAs generally characterize pluripotent cells. They are expressed not only in ESCs but also in maGSCs as well as in the F9 embryonic carcinoma cell (ECC) line. In addition, we tested the time-dependent influence of different factors that promote loss of pluripotency on levels of these miRNAs in all three pluripotent cell types. Despite the differences regarding time and extent of differentiation observed between ESCs and maGSCs, expression profiles of both miRNA families showed similarities between these two cell types, suggesting similar underlying mechanisms in maintenance of pluripotency and differentiation. Our results indicate that the 290-miRNA family is connected with Oct-4 and maintenance of the pluripotent state. In contrast, members of the 302-miRNA family are induced during first stages of in vitro differentiation in all cell types tested. Therefore, detection of miRNAs of miR-302 family in pluripotent cells can be attributed to the proportion of spontaneously differentiating cells in cultures of pluripotent cells. These results are consistent with ESC-like nature of maGSCs and their potential as an alternative source of pluripotent cells from non-embryonic tissues.