Thyroid transcription factor-1 (synonyms: Homeobox protein Nkx-2.1) is a 371 amino acid protein, 39 KDa, which belongs to the NKX homeobox transcription factor family. TTF-1 stimulates or represses transcription of particular genes by binding to their regulatory sequences. TTF-1 plays a role in regulating genes in the thyroid, lung and brain. Its molecular targets in the thyroid gland are thyroglobulin, thyroperoxidase and thyrotropin receptor. TTF-1 activates transcription of the genes encoding these proteins. In lung, TTF-1 promotes the transcription of the surfactant proteins A to D, and the Clara cell secretory protein. In brain, the molecular targets of TTF-1 are unknown. Besides being a tissue-specific transcription promoter in adult organs, TTF-1 has been suggested a role in morphogenesis and cytodifferentiation. Among thyroid neoplasms, TTF1 is seen in virtually all tumors of follicular derivation. In diagnostic pathology, TTF-1 is useful as marker for pulmonary adenocarcinoma and pulmonary neuroendocrine malignancy, including small cell lung carcinoma. It can be used to differentiate primary lung adenocarcinoma from metastasis of extrapulmonary origin.
Thyroid transcription factor-1 (synonyms: Homeobox protein Nkx-2.1) is a 371 amino acid protein, 39 KDa, which belongs to the NKX homeobox transcription factor family. TTF-1 stimulates or represses transcription of particular genes by binding to their regulatory sequences. TTF-1 plays a role in regulating genes in the thyroid, lung and brain. Its molecular targets in the thyroid gland are thyroglobulin, thyroperoxidase and thyrotropin receptor. TTF-1 activates transcription of the genes encoding these proteins. In lung, TTF-1 promotes the transcription of the surfactant proteins A to D, and the Clara cell secretory protein. In brain, the molecular targets of TTF-1 are unknown. Besides being a tissue-specific transcription promoter in adult organs, TTF-1 has been suggested a role in morphogenesis and cytodifferentiation. Among thyroid neoplasms, TTF1 is seen in virtually all tumors of follicular derivation. In diagnostic pathology, TTF-1 is useful as marker for pulmonary adenocarcinoma and pulmonary neuroendocrine malignancy, including small cell lung carcinoma. It can be used to differentiate primary lung adenocarcinoma from metastasis of extrapulmonary origin.