Using multiple high performance liquid chromatography (HPLC) steps, a protein of 12 kDa was purified to apparent homogeneity from rat Sertoli cell-enriched culture medium (SCCM). Partial N-terminal amino acid sequence analysis revealed a sequence of NH2-IQKTPQIQVYS which is identical to β2-microglobulin (β2MG) previously identified in the brain. Studies by sequential reverse transcription and polymerase chain reaction (RT-PCR) indicated that β2MG mRNA was expressed in Sertoli but not in germ cells suggesting that Sertoli cells are the source of this protein in the seminiferous epithelium behind the blood-testis barrier. The steady-state β2MG mRNA level in Sertoli cells cultured in vitro was not affected by either follicle stimulating hormone (FSH), testosterone, estradiol, dexamethasone or several cytokines such as interleukin-1β (IL-Iβ), interleukin 6 (IL-6), and transforming growth factor β (TGF-β), with the exception of interferon-γ (INFγ) which induced a dose-dependent stimulation of β2MG mRNA. The possible physiological significance of this protein in the male reproductive tract is discussed.
- Steroli cells