title: Expression of MSX1 in human normal pituitaries and pituitary adenomas.
abstract: Transcription factors play specific roles in the development and differentiation of normal pituitary tissues and pituitary adenoma. The transcription factor, muscle segment homeobox 1 (MSX1), which belongs to the homeobox gene family, binds the promoter region of the glycoprotein hormone alpha-subunit (SU) in TSH-producing cells in the mouse pituitary and regulates alpha-SU expression. The present study investigated MSX1 expression in the normal human pituitary. In addition, 50 pituitary adenomas were examined using immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) to clarify the role of MSX1 in the development and functional differentiation of pituitary adenoma cells. In the normal pituitary, MSX1 was predominantly expressed in the cytoplasm of GH-producing cells. Furthermore, MSX1 immunoreactivity was observed in the cytoplasm of some alpha-SU-producing cells. It is interesting to note that, in the pituitary adenoma, MSX1 was expressed in the nucleus of GH- and TSH-producing adenomas. RT-PCR using RNA extracted and purified from formalin-fixed paraffin-embedded pituitary adenoma specimens revealed MSX1 mRNA expressed in GH- and TSH-producing adenomas. Immunoelectron microscopy demonstrated MSX1 localized at intranuclear heterochromatin and euchromatin, which suggests transcriptional activity. These results suggest that MSX1 plays a specific role in human pituitary adenoma.
authors: Department of Neurosurgery, School of Medicine, Tokai University, Isehara, Kanagawa, Japan.
authors: Yoshihito
authors: Y
authors: Mizokami
authors: Noboru
authors: N
authors: Egashira
authors: Susumu
authors: S
authors: Takekoshi
authors: Johbu
authors: J
authors: Itoh
authors: Yoshiko
authors: Y
authors: Itoh
authors: Robert Yoshiyuki
authors: RY
authors: Osamura
authors: Mitsunori
authors: M
authors: Matsumae
mesh_terms: D000236:Adenoma / Q000235:genetics* / Q000473:pathology / Q000648:ultrastructure; D000818:Animals; D001344:Autopsy; D015153:Blotting, Western; D002454:Cell Differentiation; D017931:DNA Primers; D006801:Humans; D007150:Immunohistochemistry; D051957:MSX1 Transcription Factor / Q000235:genetics*; D051379:Mice; D016253:Microscopy, Immunoelectron; D010902:Pituitary Gland / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D010911:Pituitary Neoplasms / Q000235:genetics* / Q000473:pathology / Q000648:ultrastructure; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D051957:MSX1 Transcription Factor; C484083:MSX1 protein, human; C484084:Msx1 protein, mouse; D012333:RNA, Messenger; D012334:RNA, Neoplasm