title: B-Myc, a proximal caput epididymal protein, is dependent on androgens and testicular factors for expression.
abstract: The myc family of transcriptional regulators carries out critical roles in the control of cellular proliferation, differentiation, apoptosis, and tumorigenesis. The B-myc gene is a recently identified myc family member that has not been well characterized. Previously, we have shown that B-Myc inhibits the ability of c-Myc to transform cells and can inhibit cellular proliferation. Because B-myc is primarily expressed in hormonally regulated tissues with predominant expression in the epididymis, we examined in greater detail B-myc expression in the epididymis to ultimately understand potential roles B-myc may play in this and other hormonally regulated tissues. Herein we demonstrate that, in contrast to c-myc, B-myc mRNA and protein expression are highly regionalized with expression predominantly in the proximal caput epididymal region. Furthermore, in situ and immunohistochemical analyses show that within the epididymis B-myc mRNA and protein are specifically expressed by the epithelial cells and that B-Myc protein is localized to both the nuclear and cytosolic compartments. Castration and hormone replacement studies further show that expression of the B-myc mRNA is highly dependent on the presence of androgens and testicular factors. Finally, mRNA turnover studies demonstrate that the B-myc mRNA is relatively unstable with a half-life of 3.5 h. Taken together, the highly restricted and regulated expression of the B-myc gene suggests it may play important regulatory roles in the epididymis and perhaps other hormonally regulated tissues.
authors.affiliation: Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA. gail.cornwall@ttmc.ttuhsc.edu
authors.forename: G A
authors.initials: GA
authors.lastname: Cornwall
authors.forename: R
authors.initials: R
authors.lastname: Collis
authors.forename: Q
authors.initials: Q
authors.lastname: Xiao
authors.forename: N
authors.initials: N
authors.lastname: Hsia
authors.forename: S R
authors.initials: SR
authors.lastname: Hann
mesh_terms: D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D003609:Dactinomycin / Q000494:pharmacology; D004355:Drug Stability; D004822:Epididymis / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D013737:Testis / Q000378:metabolism*
chemical_list: D000728:Androgens; C431443:Bmyc protein, mouse; D019384:Nucleic Acid Synthesis Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D003609:Dactinomycin