Members of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway are present and active in human sperm

Objective: To investigate whether components of the Janus kinase/signal tra nsducers and activators of transcription (JAK/STAT) pathway are present and active in human sperm. Design: Comparative study. Setting: Reproductive biology department. Patient(s): Nine sperm donors. Intervention(s): Sperm were exposed to interferon-alpha (IFN-alpha), IFN-ga mma, interleukin-12 (IL-12), Ca2+ ionophore (A23187), or progesterone under capacitating conditions. Main Outcome Measure(s): Cell lysates prepared from sperm and Jurkat T-cell line were resolved by sodium dodecyl sulfate-polyacrylamide gel electropho resis and the expression of JAKs (1-3 and TYK 2) and STATs (1-6) was examin ed by Western blot analysis. Effect of IFN-alpha, IFN-gamma, IL-12, A23187, or progesterone on sperm STAT I or STAT 4 phosphorylation was determined b y phospho-STAT 1 antibody or antiphosphotyrosine (APT) Western blot analysi s. Indirect immunofluorescence and confocal laser scanning microscopy was u sed to confirm the specific staining of anti-TYK 2, anti-STAT 1, and anti-S TAT 4 antibodies. Result(s): By Western blot analysis, only antibodies to TYK 2 of the JAK fa mily, and antibodies to STAT I and STAT 4 members of the STAT family specif ically recognized protein bands corresponding to TYK 2, STAT 1, and STAT 4 described in other cell types. By confocal microscopy, antibodies to TYK 2 reacted with the sperm tail as well as the apical region of sperm head, whe reas antibodies to STAT I and STAT 4 reacted with the apical region of the sperm head. Tyrosine phosphorylation of STAT I in capacitated sperm was enh anced by IFN-alpha and IFN-gamma, and that of STAT 4 was enhanced by IL-12. Both A23187 and progesterone markedly inhibited tyrosine, phosphorylation of sperm STAT 4. Conclusion(s): Members of the JAK/STAT proteins, TYK 2, STAT 1, and STAT 4 are present and active in human sperm. The localization of STAT I and STAT 4 proteins to the apical region of the sperm head and their activation by I FN-alpha, IFN-gamma, or IL-12 implicate a role for sperm STAT proteins in f ertilization. We hypothesize that sperm-derived phosphorylated. STAT I and STAT 4 could contribute to the pool of transcription factors during sperm-o ocyte, fusion as well as transmit signal to the oocyte nucleus. Therefore, defects in sperm TYK 2 and STAT 1- or STAT 4-mediated signaling pathway may have relevance to male factor infertility. (C) 2001 by American Society fo r Reproductive Medicine.