TGFβ-Induced Proteins in Non-Endocrine Mouse Pituitary Cell Line TtT/GF

TtT/GF is a mouse pituitary cell line derived from radiothyroidectomy-induced thyrotropic pituitary tumor and has been recognized as a model of folliculostellate cells. Our previous studies suggested that TtT/GF cells have cellular plasticity, rather than representing a model only for folliculostellate cells. We found that transforming growth factor beta (TGFβ) reinforces pericyte properties (Tsukada et al. Cell and Tissue Research, 371: 339-350, 2018). In order to extensively identify TGFβ-induced proteins in TtT/GF cells, the present study performed mass spectrometry analysis combined with the stable isotope labeling of amino acids in cell culture (SILAC) system. TtT/GF cells were cultured in either light medium (containing normal Arg/Lys) or heavy medium (containing 13C6-labelled Arg/Lys) in the presence of vehicle (light), TGFβ (heavy), or selective TGFβ receptor I inhibitor (SB431542, heavy). Collected proteins were then analyzed by mass spectrometry. We successfully found 51 up-regulated and 112 down-regulated proteins, which are related to actin cytoskeleton, cell adhesion, extracellular matrix, and DNA replication. The result also showed up-regulation of many pericyte markers/pointers, supporting our previous hypothesis. Intriguingly, we found down-regulation of several pituitary adenoma markers. Mass spectrometry data using SILAC will provide valuable information about pathological processes in pituitary adenomas, as well as pericyte differentiation.