Effects of protein transduction with intact myogenic transcription factors tagged with HIV-1 Tat-PTD (T-PTD) on myogenic differentiation of mouse primary cells.

HIV-1 Tat PTD (T-PTD) has been shown to be a useful carrier for delivering transcription factors into living cells. Tissue specific transcription factors tagged with T-PTD sequences could penetrate into cells and induce tissue-specific differentiation. Meanwhile, many eukaryotic transcription factors containing basic helix-loop-helix (bHLH) motifs have been reported to facilitate protein transduction. In the present work, we developed a method to achieve efficient differentiation of primary cells using transcription factors tagged with T-PTD. MyoD and myogenin are myogenic transcription factors having bHLH domains, and we examined the effects of MyoD, T-PTD-fused MyoD (T-PTD-MyoD) and T-PTD-fused myogenin (T-PTD-MyoG) proteins on the differentiation of mouse primary cells. Although mouse primary cells were differentiated to be multi-nucleated cells (myogenic differentiation) by the addition of unmodified MyoD protein, about four times more differentiated cells were observed when we used modified MyoD, whose N-terminal region was tagged with T-PTD. These results indicated that MyoD protein combined with T-PTD could induce effective cell differentiation.