Porcine growth hormone induces the nuclear localization of porcine growth hormone receptor in vivo

OBJECTIVE Recent studies have challenged the traditional paradigm that growth hormone receptor (GHR) displays physiological functions only in the cell membrane. It has been demonstrated that GHR localizes to the cell nucleus and still exhibits important physiological roles. The phenomenon of nuclear localization of growth hormone (GH)-induced GHR has previously been described in vitro. However, until recently, whether GH could induce nuclear localization of GHR in vivo was unclear. METHODS In the present study, we used pig as an animal model, and porcine growth hormone (pGH) or saline was injected into the inferior vena cava. We subsequently observed the localization of porcine growth hormone receptor (pGHR) using multiple techniques, including, immunoprecipitation and Western-blotting, indirect immunofluorescence assay and electronmicroscopy. RESULTS The results showed that pGH could induce nuclear localization of pGHR. Taken together, the results of the present study provided the first demonstration that pGHR was translocated to cell nuclei under pGH stimulation in vivo. CONCLUSION Nuclear localization of pGHR induced by the in vivo pGH treatment suggests new functions and/or novel roles of nuclear pGHR, which deserve further study.