Signal transducers and activators of transcription (Stat) are detectable in mouse trigeminal ganglion neurons

We studied signal transducers and activators of transcription (Stat) expres sion in mouse trigeminal ganglia (TG) to gain an understanding of herpes si mplex virus (HSV) infection and reactivation, Mouse TG were harvested and w ere either frozen for Western blot analysis or preserved in 4% paraformalde hyde for subsequent immunohistochemistry study. The thawed specimens were h omogenized, and nuclear/cytoplasmic extractions were performed for Western blots and immunoprecipitation. Immunohistochemistry showed that Stat1, Stat 3. Stat4, Stat5b, and phosphotyrosine Stat3 localized to TG neurons, not su rrounding satellite cells. Western blot of TG nuclear and cytoplasmic extra cts confirmed the presence of these Stat at the appropriate molecular weigh ts. Stat2 was undetectable in TG by these methods, Immunoprecipitation of T G nuclear extracts did not confirm the presence of Stat-Stat dimers in thes e specimens. These studies show that several Stat, including phosphotyrosin e Stat3, are present in TG neurons, the site of HSV latency, where they cou ld act upon latent viral DNA to effect reactivation.