Creation of estrogen resistance in vivo by transgenic overexpression of the heterogeneous nuclear ribonucleoprotein-related estrogen response element binding protein.
Estrogen unresponsiveness among primate species can result from overexpression of a heterogeneous nuclear ribonucleoprotein (hnRNP) that competes with estrogen receptor (ER) for binding to the estrogen-response element (ERE). This hnRNP has been coined the "ERE-binding protein" (ERE-BP). The ERE-BP is a member of the hnRNP C-like subfamily of hnRNPs, traditionally considered to be single-strand RNA binding proteins designed for the stabilization and handling of pre-mRNA. To verify in vivo the dominant-negative actions of the ERE-BP to inhibit ER-ERE-directed transactivation and to avoid the potential for lethality from global overexpression of an hnRNP, we generated transgenic mice that overexpressed ERE-BP in breast tissue under the control of a whey acidic protein gene promoter. Graded overexpression of ERE-BP in transgenic mice was established. Founders were viable and fertile. Female transgenics in all lines gave birth to pups, but their ability to nurse was dependent on the level of ERE-BP expression in breast; high-ERE-BP expressors were unable to lactate. A gradient of impaired breast pheno(histo)type, from near normal to failed ductal development and lactational capacity, correlated with the relative level of transgene expression. ERE-BP, expressed either endogenously as a transgene or after transfection, colocalized with ERalpha in the nucleus of target cells. This work confirms that tissue-targeted overexpression of the ERE-BP can effectively block estrogen-ERalpha-ERE-directed action in vivo.
Burns and Allen Research Institute and Division of Endocrinology, Diabetes, and Metabolism, Cedars-Sinai Medical Center, David Geffen School of Medicine at the University of California, Los Angeles, California 90048, USA. chenh@cshs.org
Hong
H
Chen
William
W
Stuart
Bing
B
Hu
Lisa
L
Nguyen
Ganghua
G
Huang
Thomas L
TL
Clemens
John S
JS
Adams
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D004351:Drug Resistance; D047628:Estrogen Receptor alpha / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D017930:Genes, Reporter; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000235:genetics*; D007438:Introns; D008156:Luciferases / Q000235:genetics; D008321:Mammary Glands, Animal / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D008894:Milk Proteins / Q000235:genetics; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002352:Carrier Proteins; D047628:Estrogen Receptor alpha; D004967:Estrogens; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D008894:Milk Proteins; C024471:whey acidic proteins; D008156:Luciferases