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General Comment |
Tohlh1 is essential for spermatogonial differentiation. Ballow D et al. Spermatogonia are adult germline stem cells that can both self-renew and differentiate into spermatocytes. Little is known about factors necessary for spermatogonial differentiation. We identified a novel germ-cell-specific transcription factor that we named Tohlh1 (testis and ovary expressed basic helix-loop-helix (bHLH) transcription factor). In males, Tohlh1 is preferentially expressed in prespermatogonia and Type A spermatogonia. Loss of Tohlh1 causes infertility by disrupting spermatogonial differentiation into spermatocytes. Seven-day-old testes without Tohlh1 still express the testis-specific transcription factors Etv5, Taf4b, Zfp148, and Plzf, overexpress a novel Tohlh2 bHLH transcription factor, but lack LIM homeobox gene Lhx8 and show reduced expression of Ngn3. Tohlh1 represents the first testis-specific bHLH transcription factor that is essential for spermatogonial differentiation.
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