PURIFICATION AND CELLULAR-LOCALIZATION OF BETA(2)-MICROGLOBULIN IN THE TESTIS

Using multiple high performance liquid chromatography (HPLC) steps a p rotein of 12 kDa was purified to apparent homogeneity from rat Sertoli cell-enriched culture medium (SCCM). Partial N-terminal amino acid se quence analysis revealed a sequence of NH2-IQKTPQIQVYS which is identi cal to beta(2)-microgrobulin (beta(2)MG) previously identified in the brain. Studies by sequential reverse transcription and polymerase chai n reaction (RT-PCR) indicated that beta(2)MG mRNA was expressed in Ser toli but not in gen cells suggesting that Sertoli cells are the source of this protein in the seminiferous epithelium behind the blood-testi s barrier. The steady-state beta(2)MG mRNA level in Sertoli cells cult ured in vine was not affected by either follicle stimulating hormone ( FSH), testosterone, estradiol, dexamethasone or several cytokines such as interleukin-1 beta (IL-1 beta), interleukin 6 (IL-6), and transfor ming growth factor beta(TGF-beta), with the exception of interferon-ga mma (INF gamma) which induced a dose-dependent stimulation of beta(2)M G mRNA. The possible physiological significance of this protein in the male reproductive tract is discussed.