LH Induces Orphan Nuclear Receptor Nur77 Gene Expression in Testicular Leydig Cells

Abstract

The orphan nuclear receptor Nur77 (NR4A1) is a member of the nuclear receptor superfamily and plays an important role in the regulation of genes involved in steroidogenesis and cell death. Northern blot analysis revealed that the expression of Nur77 mRNA was increased after puberty in mouse testis, and hCG treatment of peripubertal animals induced this gene expression in the testis. Moreover, LH treatment induced a transient increase in Nur77 mRNA, and this induction was LH dose dependent in mouse Leydig tumor cell line, K28. Western blot analysis showed that LH transiently induced Nur77 protein. The protein kinase inhibitor H-89, bisindolymaleimide I, and wortmannin strongly inhibited this inductive effect of LH on Nur77 gene expression. Transient transfection assay demonstrated that LH significantly increased the Nur77 promoter-driven luciferase reporter activity in a dose-dependent manner, and LH also increased the activity of a luciferase reporter gene driven by a promoter containing multi copies of a Nur77-responsive element. Moreover, EMSA showed that Nur77 DNA-binding activity was increased in response to LH. Finally, overexpression of dominant negative Nur77 reduced LH-mediated progesterone biosynthesis. Taken together, these results demonstrate that LH induces Nur77 gene expression, and Nur77 may play an important role in the LH-mediated steroidogenesis in Leydig cells.

Calcium-dependent Nr4a1 expression in mouse Leydig cells requires distinct AP1/CRE and MEF2 elements

“…A similar kinetic was observed in MA-10 Leydig cells treated with forskolin (Fsk) (Martin et al 2008). LH/ Fsk-induced Nr4a1 expression is blunted in the presence of inhibitors of RyRs and CaM (Abdou et al 2013), protein kinase A (PKA) (Song et al 2001), phosphoinositide-3 kinase (PI3K) (Song et al 2001), and CAMK ).…”

“…In steroidogenic Leydig cells, NR4A1 protein and Nr4a1 mRNA levels are induced as early as 30 min post LH/hCG stimulation and peak at 2 h before rapidly decreasing to undetectable levels by 3 h (Song et al 2001). A similar kinetic was observed in MA-10 Leydig cells treated with forskolin (Fsk) (Martin et al 2008).…”

Angiotensin II Triggers Expression of the Adrenal Gland Zona Glomerulosa-Specific 3β-Hydroxysteroid Dehydrogenase Isoenzyme through De Novo Protein Synthesis of the Orphan Nuclear Receptors NGFIB and NURR1

“…This protein is defective in transactivation function but shares the same DNA sequence binding specificity with the NGFIB family. Thus, the DN-NGFIB protein acts as an inhibitor for all three subfamily members: NGFIB, NURR1, and NOR1 (29,30). For coexpression of DN-NGFIB with a cell surface marker protein, H-2K k (Miltenyi Biotec), we used the pMACS K k .II expression vector (Miltenyi Biotec), which allows the simultaneous expression of H-2K k and the gene of interest from a single vector.…”

“…For this analysis, we used two different experimental tools, small interfering RNAs (siRNAs) targeting NGFIB and NURR1 (Fig. 7) and a dominant negative NGFIB (DN-NGFIB) that is known to competitively inhibit all members of the NGFIB family (29,30) (Fig. 8).…”

Stimulation of orphan nuclear receptor HR38 gene expression by PTTH in prothoracic glands of the silkworm, Bombyx mori

“…It is well documented that NR4A gene expression is differentially regulated in a stimulus-and cell type-specific manner. Luteinizing hormone induces NGF-I B expression via protein kinase A (PKA), calmodulin kinase II, and MAPK pathways (Song et al, 2001). Parathyroid hormone induces NR4A receptors through PKA and protein kinase C (PKC) pathways (Pirih et al, 2003).…”