Differentially expressed nucleolar TGF-β1 target (DENTT) shows tissue-specific nuclear and cytoplasmic localization and increases TGF-β1-responsive transcription in primates

Abstract

Differentially Expressed Nucleolar TGF-β1 Target (DENTT) is a new member of the TSPY/TSPY-like/SET/NAP-1 (TTSN) superfamily whose mRNA is induced by TGF-β1 in TGF-β1-responsive human lung cancer cells. Monkey DENTT mRNA contains a 2085-bp open reading frame that encodes a predicted polypeptide of 695 amino acids with five nuclear localization signals, two coiled-coil regions, and a domain that shows significant identity to a region that defines the TTSN superfamily. RT-PCR amplification and Western blot analyses showed DENTT mRNA and protein in adult monkey tissues, including the adrenal gland, cerebral cortex, and ovary. Immunohistochemical staining showed that numerous neurons were intensely immunoreactive for DENTT, as were anterior pituitary secretory cells, thyroid follicular cells, and smooth muscle cells of arteries and lung bronchial walls. DENTT expression was also prominent in monkey bronchiolar-alveolar adenomas and cell lines. While the addition of TGF-β1 or retinoic acid to monkey normal lung bronchial 12MBr6 cells and human lung cancer NCI-H727 cells increased DENTT protein production, TGF-β1 together with retinoic acid resulted in a more sustained increase in DENTT production than with TGF-β1 or retinoic acid alone. Transient transfection studies showed that ectopic DENTT expression significantly increased TGF-β1-responsive 3TP-Lux and CAGA12-Lux reporter transcription in 12MBr6 and NCI-H727 cells with TGF-β1 addition, while ectopic DENTT expression had no significant effect on the transcription of a retinoic acid-responsive element reporter in the presence of retinoic acid or TGF-β1. These findings suggest new possibilities for DENTT as a TGF-β1-regulated, but not a retinoic acid-regulated member of the TTSN superfamily in primate physiology.