Overexpression of bone morphogenetic protein 4 in STO fibroblast feeder cells represses the proliferation of mouse embryonic stem cells in vitro

Embryonic stem cells (ESCs) can be propagated in vitro on feeder layers of mouse STO fibroblast cells. The STO cells secrete several cytokines that are essential for ESCs to maintain their undifferentiated state. In this study, we found significant growth inhibition of mouse ESCs (mESCs) cultured on STO cells infected with adenovirus containing a dominant-negative mutant form of IkappaB (rAd-dnIkappaB). This blockage of the NF-kappaB signal pathway in STO cells led to a significant decrease in [3H]thymidine incorporation and colony formation of mESCs. Expression profile of cytokines secreted from the STO cells revealed an increase in the bone morphogenetic protein4 (BMP4) transcript level in the STO cells infected with adenoviral vector encoding dominant negative IkappaB (rAd-dnIkappaB). These results suggested that the NF-kappaB signaling pathway represses expression of BMP4 in STO feeder cells. Conditioned medium from the rAd-dnIkappaB-infected STO cells also significantly reduced the colony size of mESCs. Addition of BMP4 prevented colony formation of mESCs cultured in the conditioned medium. Our finding suggested that an excess of BMP4 in the conditioned medium also inhibits proliferation of mESCs.

Capsaicin promotes the development of burst-forming nits-erythroid (BFU-E) from mouse bone marrow cells

Capsaicin, the pungent component of chilli peppers, is known to induce mediators of hematopoiesis. We investigated the effect of capsaicin on hematopoiesis in mouse progenitor cells. Treatment of mouse bone marrow cells with capsaicin induced the formation of colony of burst-forming units-erythroid (BFU-E). We also found that the number of erythropoietin receptor (EpoR)-positive cells was increased by capsaicin. To clarify the effect of capsaicin on erythroid lineage, BFU-E colonies were separated from non-BFU-E colonies by colony-picking after in vitro culture of mouse bone marrow cells. Quantitative RT-PCR analysis revealed that capsaicin stimulated the expression of the erythroid-specific genes encoding EpoR, glycophorin A (GPA), beta-globin (Hbb-b1), GATA-1, PU.1, nuclear factor erythroid-derived 2 (NF-E2), and Kruppel-like factor 1 (KLF1) in the BFU-E colonies. Furthermore, capsaicin could effectively stimulate the transfected GATA-1 promoter in K562 cells. GATA-1 is known as an essential transcription factor for the development of erythroid cells. Our results show that development of the erythroid lineage from bone marrow cells can be induced by treatment with capsaicin, and that GATA-1 seems to play a role in this induced erythroid maturation.