CREBZF expression and hormonal regulation in the mouse uterus

Abstract

BackgroundCREBZF is a member of the mammalian ATF/CREB family of the basic region-leucine zipper (bZIP) transcription factors. Two isoforms of CREBZF have been identified from the alternative usage of initiation codons, SMILE (long isoform of CREBZF) and Zhangfei (short isoform of CREBZF). Until recently, the physiological function of CREBZF in mammalian reproductions has not been reported.MethodsMultiple techniques were performed to investigate the spatiotemporal expression and hormonal regulation of the CREBZF gene in the mouse uterus and its role in embryo implantation.ResultsZhangfei was not detected in the mouse uterus. SMILE immunostaining was mainly expressed in the uterine luminal and glandular epithelium, and the expression levels of both SMILE mRNA and protein gradually decreased from days 1–3 of pregnancy, peaked on day 4, and then declined again on day 6. On day 5 of pregnancy, SMILE protein expression was detected only in the luminal epithelium at implantation sites compared with the expression at inter-implantation sites. SMILE protein was not detected in decidual cells from days 6–8 of pregnancy or artificial decidualisation. Furthermore, SMILE protein was not detected in the mouse uterus on days 3–6 of pseudopregnancy, and SMILE expression was also induced in the delayed-implantation uterus, indicating that the presence of an active blastocyst was required for SMILE expression at the implantation site. Oestrogen significantly stimulated SMILE expression in the ovariectomised mouse uterus. In addition, in cycling mice, high levels of SMILE protein and mRNA expression were also observed in proestrus and oestrus uteri.ConclusionsTaken together, these results suggested that SMILE expression was closely related to mouse implantation and up-regulated by oestrogen.

Hormone regulates endometrial function via cooperation of endoplasmic reticulum stress and mTOR‐autophagy

“…Our previous studies have reported that 78‐kDa glucose‐regulated protein (GRP78), which is the main regulator of UPR, is significantly increased in implantation site on day 5 in mice (Lin et al, ). ERS‐response‐regulated protein, CREBZF, CREB3 (Luman), and CREBRF (LRF), are also up‐regulated in implantation site in mice (Lan et al, ; Li et al, ; Lin et al, ; Yang, Jin, Lin, et al, ; Yang, Jin, Martyn, et al, ). Therefore, our limited knowledge leads us to speculate that ER stress is involved in regulating embryo implantation in mice.…”

Regulation of Cyclic AMP-Response Element Binding Protein Zhangfei (CREBZF) Expression by Estrogen in Mouse Uterus

“…Recently, CREBZF regulates bone formation and adipocyte differentiation by interacting transcription factors ( Jang et al, 2014 ; Jang et al, 2015 ). Also, recent study indicated that CREBZF is induced by estrogen and closely related to implantation ( Lin et al, 2013 ). However, this study is unclear and lacks the correlation between estrogen and CREBZF expression in endometrium of uterus.…”

Expression and regulation of ATF6α in the mouse uterus during embryo implantation

“…Immunohistochemistry was performed as previously described [ 29 ]. Uterine tissue was immersed in a 4 % formaldehyde solution for 24 h. Then, the tissue was dehydrated gradually in serial concentrations of alcohol and was completely immersed in liquid paraffin.…”

“…Finally, the sections were treated with 3, 3′-diaminobenzidine (DAB) (Sigma-Aldrich Corp., St. Louis, MO, USA) and hematoxylin. For the sections from the negative control group, the ATF6α antibody was replaced with normal rabbit IgG (SC-2763, 1:100, Santa Cruz Biotechnology, Inc., Dallas, Texas, USA) according to our previous report [ 29 ].…”

“…Following the manufacturer’s instructions, total RNA was extracted from the mouse uterine tissue by treatment with TRIzol and deoxyribonuclease (Takara Biotechnology, Co., Ltd., Dalian, China). The total RNA concentration was measured as previously described [ 29 ]. cDNA was synthesized using a reverse transcription kit (Takara Biotechnology, Co., Ltd., Dalian, China).…”