The AF-1 activation-function of ERalpha may be dispensable to mediate the effect of estradiol on endothelial NO production in mice.
Two isoforms of estrogen receptor (ER) have been described: ERalpha and ERbeta. The initial gene targeting of ERalpha, consisting in the introduction of a Neo cassette in exon 1 [alphaERKO, hereafter called ERalpha-Neo KO (knockout)], was reported in 1993. More recently, another mouse deficient in ERalpha because of the deletion of exon 2 (ERalphaKO, hereafter called ERalpha-delta2 KO) was generated. In ovariectomized ERalpha-wild-type mice, estradiol (E(2)) increases uterine weight and basal production of endothelial nitric oxide (NO). Both of these effects are abolished in ERalpha-delta2 KO mice. In contrast, we show here that both of these effects of E(2) are partially (uterine weight) or totally (endothelial NO production) preserved in ERalpha-Neo KO. We also confirm the presence of two ERalpha mRNA splice variants in uterus and aorta from ERalpha-Neo KO mice. One of them encodes a chimeric ERalpha protein (ERalpha55), partially deleted in the A/B domain, that was detected in both uterus and aorta by Western blot analysis. The other ERalpha mRNA splice variant codes for an isoform deleted for the A/B domain (ERalpha46), which was detected in uterus of ERalpha-Neo KO, and wild-type mice. This protein isoform was not detected in aorta. The identification of these two N-terminal modified isoforms in uterus, and at least one of them in aorta, probably explains the persistence of the E(2) effects in ERalpha-Neo KO mice. Furthermore, ERalpha-Neo KO mice may help in the elucidation of the specific functions of full-length ERalpha (ERalpha66) and ERalpha46, both shown to be physiologically generated in vivo.
Pendaries
C
C
Institut National de la Santé et de la Recherche Médicale U397 et Laboratoire de Physiologie, Institut Louis Bugnard, Centre Hospitalier Universitaire Rangueil, 31054 Toulouse, France.
Darblade
B
B
Rochaix
P
P
Krust
A
A
Chambon
P
P
Korach
K S
KS
Bayard
F
F
Arnal
J F
JF
D017398:Alternative Splicing; D000818:Animals; D001011:Aorta / Q000378:metabolism; D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D005091:Exons; D005260:Female; D006984:Hypertrophy; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D008957:Models, Genetic; D016254:Mutagenesis, Insertional; D009569:Nitric Oxide / Q000096:biosynthesis*; D009929:Organ Size; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics* / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D047628:Estrogen Receptor alpha; D020033:Protein Isoforms; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D009569:Nitric Oxide; D004958:Estradiol