Overexpression of STRA8, BOULE, and DAZL Genes Promotes Goat Bone Marrow-Derived Mesenchymal Stem Cells In Vitro Transdifferentiation Toward Putative Male Germ Cells

Bone marrow mesenchymal stem cells (BMSCs), which are well characterized and widely utilized adult stem cells, encompass the capacity to commit to a variety of cell types. This study was conducted to develop an effective way to induce goat BMSCs (gBMSCs) to transdifferentiate toward putative male germ cells by overexpressing STRA8 (stimulated by RA-8), BOULE (also called BOLL), and DAZL (deleted in azoospermia-like). First, we found that the expression levels of these 3 genes gradually increased during development of the goat testis from 10 days postnatal to 8 months old. Therefore, we hypothesized that overexpressing these genes might contribute to the transdifferentiation of gBMSCs toward germ cells. We then overexpressed, separately and in combination, STRA8, BOULE, and DAZL in gBMSCs. Our results showed that a small population of transfected gBMSCs transdifferentiated into early goat germ cell-like cells and that these cells expressed primordial germ cell specification genes STELLA (also known as DPPA3, developmental pluripotency associated 3) and C-KIT (tyrosine kinase receptor) as well as premeiotic genes MVH (mouse vasa homolog), DAZL, BOULE, STRA8, PIWIL2 (piwi-like RNA-mediated gene silencing 2), and RNF17 (ring finger protein 17). Importantly, results from quantitative reverse transcription polymerase chain reaction, immunofluorescence, and Western blot analysis showed that the meiotic marker synaptonemal complex protein 3 (SCP3) significantly increased in transfected cells compared to untransfected control cells ( P < .05). Additionally, the co-overexpression group cells had the highest SCP3 messenger RNA and protein expression levels, which indicated that 3-gene co-overexpression had the highest potential to transdifferentiate gBMSCs to germ cells. Taken together, these results demonstrate that the overexpression of STRA8, BOULE, and DAZL was able to promote the transdifferentiation of gBMSCs to early goat germ cell-like cells in vitro, which probably enhanced maturation and progression through meiosis. This approach would be important to generating gametes for future basic science as well as for potential clinical applications.