Sex Differences in Androgen Receptor Enhancer Activity and Expression during Mus musculus Embryonic Development
Location
Philadelphia, PA
Start Date
8-5-2019 1:00 PM
End Date
8-5-2019 4:00 PM
Description
Study objective: The objective of this study is to compare the sex-specific enhancer function of a cis-regulatory element during mammary gland development to the expression of the androgen receptor (AR) in mammary tissues.
Introduction: Conserved noncoding elements regulate gene expression during mammalian development with remarkable precision. AR is critical for the development of male specific phenotypes in many tissues, yet little is known regarding the tissue-specific regulation of AR gene expression. We have previously identified a 7.7kb sequence near the AR gene that activates lacZ reporter gene expression in prenatal and postnatal mice. Embryologically, the enhancer drives consistent lacZ expression in developing hair follicles and the genital tubercle. However, expression in the mammary ridge/glands occurs in only half of the transgenic embryos produced. Each of these structures are known sites of expression of AR or are affected by androgens during growth and development. We hypothesize that the variability in this enhancer function during mammary gland development may be sex dependent.
Methods: We utilized a previously established transgenic mouse line containing the 7.7kb AR enhancer mouse sequence linked to a basal promoter driving lacZ. Mice were collected and stained during different stages of embryonic development to visualize localization of AR enhancer activity. The sex of the embryos were identified by PCR amplification of the Sry gene. We compared enhancer driven lacZ expression to endogenous AR expression determined by in situ hybridization (ISH) in mouse embryos.
Results: We have surveyed lacZ expression at embryonic day (E) 13.5 through E16.5. Despite consistent expression in other tissues, mammary gland expression of lacZ differs between male and female embryos. These expression results are consistent with AR gene expression as detected by ISH.
Conclusion: We show that there are sex differences in enhancer activity of AR during mouse development. AR is crucial for inhibiting the development of female-specific traits as well as promoting the male phenotype. The relative lack of lacZ expression in male embryos suggests the inhibitory effects of androgens have been sufficient to either eliminate the mammary associated cell types that normally express AR or the expression of an upstream trans-acting factor that activates this AR enhancer. This mouse line will be useful for tracing developmental progression of AR expressing tissues and signaling during mammalian integumentary development as well as the development of sexually dimorphic characteristics.
Embargo Period
5-24-2019
Sex Differences in Androgen Receptor Enhancer Activity and Expression during Mus musculus Embryonic Development
Philadelphia, PA
Study objective: The objective of this study is to compare the sex-specific enhancer function of a cis-regulatory element during mammary gland development to the expression of the androgen receptor (AR) in mammary tissues.
Introduction: Conserved noncoding elements regulate gene expression during mammalian development with remarkable precision. AR is critical for the development of male specific phenotypes in many tissues, yet little is known regarding the tissue-specific regulation of AR gene expression. We have previously identified a 7.7kb sequence near the AR gene that activates lacZ reporter gene expression in prenatal and postnatal mice. Embryologically, the enhancer drives consistent lacZ expression in developing hair follicles and the genital tubercle. However, expression in the mammary ridge/glands occurs in only half of the transgenic embryos produced. Each of these structures are known sites of expression of AR or are affected by androgens during growth and development. We hypothesize that the variability in this enhancer function during mammary gland development may be sex dependent.
Methods: We utilized a previously established transgenic mouse line containing the 7.7kb AR enhancer mouse sequence linked to a basal promoter driving lacZ. Mice were collected and stained during different stages of embryonic development to visualize localization of AR enhancer activity. The sex of the embryos were identified by PCR amplification of the Sry gene. We compared enhancer driven lacZ expression to endogenous AR expression determined by in situ hybridization (ISH) in mouse embryos.
Results: We have surveyed lacZ expression at embryonic day (E) 13.5 through E16.5. Despite consistent expression in other tissues, mammary gland expression of lacZ differs between male and female embryos. These expression results are consistent with AR gene expression as detected by ISH.
Conclusion: We show that there are sex differences in enhancer activity of AR during mouse development. AR is crucial for inhibiting the development of female-specific traits as well as promoting the male phenotype. The relative lack of lacZ expression in male embryos suggests the inhibitory effects of androgens have been sufficient to either eliminate the mammary associated cell types that normally express AR or the expression of an upstream trans-acting factor that activates this AR enhancer. This mouse line will be useful for tracing developmental progression of AR expressing tissues and signaling during mammalian integumentary development as well as the development of sexually dimorphic characteristics.
Comments
Presented at Experimental Biology 2019.