Expression of differentially expressed nucleolar transforming growth factor-beta1 target (DENTT) in adult mouse tissues.

Abstract

Differentially expressed nucleolar TGF-beta1 target (DENTT) is a novel member of the TSPY/TSPY-L/SET/NAP-1 (TTSN) superfamily that we have previously identified in human lung cancer cells. Here, we have investigated the expression of this protein in the adult mouse. By Western analysis, DENTT is highly expressed in the pituitary gland and moderately in the adrenals, brain, testis, and ovary. Immunohistochemical staining analysis for DENTT showed differential cytoplasmic and nuclear staining patterns in several cell types. The pituitary gland showed the highest level of immunostaining for DENTT, with strong cytoplasmic immunoreactivity in the anterior lobe, moderate levels in the posterior lobe, and a few cells showing nuclear staining in the intermediate lobe. In contrast, the intermediate lobe of the pituitary showed intense cytoplasmic staining for TGF-beta1. Nuclear and cytoplasmic staining for DENTT was present in the islets of Langerhans in the pancreas. Cytoplasmic staining for DENTT was particularly intense in the cortex of the adrenal gland, whereas the medulla showed weak nuclear staining. In the nervous system, the choroid plexus showed the highest immunoreactivity, with cortical motoneurons and Purkinje cells having relatively high levels of staining for DENTT as well. DENTT immunoreactivity was found in Leydig interstitial cells, Sertoli cells, and primary spermatocytes in the testis. In the female reproductive system, DENTT immunoreactivity was present in oocytes, thecal cells, and corpora lutea. The bronchial epithelium of the lung showed moderate levels of staining for DENTT localized to the cell nucleus. Additionally, three rodent pituitary cell lines (AtT20, GH3, and alphaT3-1, representing corticotropes, lactotropes, and gonadotropes, respectively) showed expression of DENTT. Addition of TGF-beta1 or serum to AtT20 cells increased DENTT protein production by 4 hr and, after reaching maximal levels at 2.4-fold above basal level by 8 hr, decreased, whereas no more than a 1.5-fold increase in DENTT protein occurred in GH3 or alphaT3-1 cells. Transient transfection studies showed that ectopic DENTT expression significantly increased the level of p3TP-Lux reporter transcription in AtT20 cells, but not in GH3 or alphaT3-1 cells. Interestingly, addition of TGF-beta1 had no significant effect on the ability of DENTT expression to influence p3TP-Lux reporter transcription in AtT20 cells. This report is the first detailed immunohistochemical examination of a member of the TTSN superfamily in the adult mouse. Expression of DENTT in endocrine tissues, nervous system, lung, oocytes, and thecal cells, in addition to the testis, suggests new roles for the TTSN superfamily. The differential patterns of expression of DENTT and TGF-beta1 in some tissues, including the pituitary, suggest that other factors are likely to be regulators of DENTT besides TGF-beta1.