Utilization of DR1 as true RARE in regulating the Ssm, a novel retinoic acid-target gene in the mouse testis

• Published in: Journal of endocrinology Vol. 192; no. 3; pp. 539 - 551
• Main Authors: Han, Kyuyong, Song, Haengseok, Moon, Irene, Augustin, Robert, Moley, Kelle, Rogers, Melissa, Lim, Hyunjung
• Format: Journal Article
• Language: English
• Published: Colchester BioScientifica 01.03.2007; Portland Press
• Subjects: Animals; Base Sequence; Biological and medical sciences; Cell Line; Cell Line, Tumor; Dimerization; DNA - analysis; Female; Fundamental and applied biological sciences. Psychology; Gene Library; Hormone metabolism and regulation; Immunoprecipitation; In Situ Hybridization; Male; Mammalian male genital system; Mice; Mice, Inbred Strains; Microscopy, Fluorescence; Molecular Sequence Data; Phosphoproteins - physiology; Receptors, Retinoic Acid - metabolism; Regular papers; Response Elements; Retinoid X Receptors - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Spermatocytes - metabolism; Testis - chemistry; Testis - metabolism; Transcription Factors - physiology; Transfection; Tretinoin - metabolism; Uterus - chemistry; Vertebrates: reproduction; Rodentia; Retinoid; Gene expression; Testicle; Male genital system; Vertebrata; Mammalia; Mouse; Animal; Adult animal; RXR retinoid receptor; Localization; Retinoic acid; Peroxisome proliferator activated receptor; Quantitative analysis
• ISSN: 0022-0795; 1479-6805
• DOI: 10.1677/JOE-06-0115

Various nuclear receptors form dimers to activate target genes via specific response elements located within promoters or enhancers. Retinoid X receptor (RXR) serves as a dimerization partner for many nuclear receptors including retinoic acid receptor (RAR) and peroxisome proliferator-activated receptor (PPAR). Dimers show differential preference towards directly repeated response elements with 1–5 nucleotide spacing, and direct repeat 1 (DR1) is a promiscuous element which recruits RAR/RXR, RXR/RXR, and PPAR/RXR in vitro. In the present investigation, we report identification of a novel RAR/RXR target gene which is regulated by DR1s in the promoter region. This gene, namely spermatocyte-specific marker (Ssm), recruits all the three combinations of nuclear receptors in vitro, but in vivo regulation is observed by trans-retinoic acid-activated RAR/RXR dimer. Indeed, chromatin immunoprecipitation experiment demonstrates binding of RARβ and RXRα in the promoter region of the Ssm. Interestingly, expression of Ssm is almost exclusively observed in spermatocytes in the adult mouse testis, where RA signaling is known to regulate developmental program of male germ cells. The results show that Ssm is a RAR/RXR target gene uniquely using DR1 and exhibits stage-specific expression in the mouse testis with potential function in later stages of spermatogenesis. This finding exemplifies usage of DR1s as retinoic acid response element (RARE) under a specific in vivo context.