TAZ ameliorates the microglia-mediated inflammatory response via the Nrf2-ROS-NF-κB pathway.

Transcriptional co-activator with PDZ-binding motif (TAZ), one of core modules of the Hippo pathway, involves inflammatory cell infiltration in the liver, but little information is available regarding its physiological function in the microglia-mediated inflammatory response. Here we revealed that activation of TAZ prevented microglia production of proinflammatory cytokines, indicating TAZ's importance in anti-inflammation. After translocation into the nucleus, TAZ interacted with transcriptional enhanced associate domain (TEAD) and bound to the promoter of nuclear factor erythroid 2-related factor 2 (Nrf2), whose blockage caused inability of TAZ to improve inflammation, implying that Nrf2 is a direct target of TAZ. Further analysis showed that TAZ induced Nrf2 nuclear translocation to enhance antioxidant capacity with attenuation of oxidative stress and the inflammatory response. Under inflammatory conditions, TAZ impeded mitochondrial dysfunction, as indicated by amelioration of ATP levels, mtDNA copy numbers, and mitochondrial membrane potential with an obvious reduction in mitochondrial superoxide, but this impediment was neutralized by blockage of Nrf2. TAZ hindered opening of the mitochondrial permeability transition pore, restrained release of cytochrome c from mitochondria into the cytosol, and was sufficient to rescue microglia from apoptosis dependent on Nrf2. Nrf2 acted as a downstream target of TAZ to repress NF-κB activation by enhancing antioxidant capacity. Collectively, TAZ might ameliorate the microglia-mediated inflammatory response through the Nrf2-reactive oxygen species (ROS)-nuclear factor κB (NF-κB) pathway.

Yap is essential for uterine decidualization through Rrm2/GSH/ROS pathway in response to Bmp2.

Yap is required for ovarian follicle and early embryo development, but little information is available regarding its physiological significance in decidualization. Here we determine the effects of YAP on decidualization, mitochondrial function, cell apoptosis and DNA damage, and explore its interplay with Bmp2, Rrm2, GSH and ROS. The results exhibited that Yap was abundant in decidual cells and its inactivation impaired the proliferation and differentiation of stromal cells along with the deferral of G1/S phase transition, indicating Yap importance in decidualization. Bmp2 via Alk2 receptor promoted nuclear translocation of Yap where it might interact with Tead and then bind to the promoter of Rrm2 whose activation rescued the faultiness of differentiation program and attenuated oxidative DNA damage caused by Yap impediment. Meanwhile, Yap had an important part in the crosstalk between Bmp2 and Rrm2. Furthermore, inactivation of Yap resulted in an obvious accumulation of intracellular ROS followed by the abnormal GR activity and GSH content dependent on Rrm2. Replenishment of GSH counteracted the regulation of Yap inactivation on stromal differentiation and DNA damage with distinct reduction for intracellular ROS. Additionally, blockage of Yap caused the enhancement of stromal cell apoptosis and brought about mitochondrial dysfunction as indicated by the aberration for ATP level, mtDNA copy number and mitochondrial membrane potential concomitant with the opening of mitochondrial permeability transition pore, but these abnormalities were neutralized by GSH. Administration of mitochondrial antioxidant Mito-TEMPO rescued the fault of stromal differentiation conferred by Yap inactivation. Collectively, Yap was essential for uterine decidualization through Rrm2/GSH/ROS pathway in response to Bmp2.

TAZ as a novel regulator of oxidative damage in decidualization via Nrf2/ARE/Foxo1 pathway.

TAZ, as a crucial effector of Hippo pathway, is required for spermatogenesis and fertilization, but little is known regarding its physiological function in uterine decidualization. In this study, we showed that TAZ was localized in the decidua, where it promoted stromal cell proliferation followed by accelerated G1/S phase transition via Ccnd3 and Cdk4 and induced the expression or activity of stromal differentiation markers Prl8a2, Prl3c1 and ALP, indicating the importance of TAZ in decidualization. Knockdown of TAZ impeded HB-EGF induction of stromal cell proliferation and differentiation. Under oxidative stress, TAZ protected stromal differentiation against oxidative damage by reducing intracellular ROS and enhancing cellular antioxidant capacity dependent on the Nrf2/ARE/Foxo1 pathway. TAZ strengthened the transcriptional activity of Nrf2 which directly bound to the antioxidant response element (ARE) of Foxo1 promoter region. Additionally, silencing TAZ caused accumulation of intracellular ROS through heightening NOX activity whose blockade by APO reversed the disruption in stromal differentiation. Further analysis revealed that TAZ might restore mitochondrial function, as indicated by the increase in ATP level, mtDNA copy number and mitochondrial membrane potential with the reduction in mitochondrial superoxide. Additionally, TAZ modulated the activities of mitochondrial respiratory chain complexes I and III whose suppression by ROT and AA resulted in the inability of TAZ to defend against oxidative damage to stromal differentiation. Moreover, TAZ prevented stromal cell apoptosis by upregulating Bcl2 expression and inhibiting Casp3 activity and Bax expression. In summary, TAZ might mediate HB-EGF function in uterine decidualization through Ccnd3 and ameliorate oxidative damage to stromal cell differentiation via Nrf2/ARE/Foxo1 pathway.

Genistein exhibits therapeutic potential for PCOS mice via the ER-Nrf2-Foxo1-ROS pathway.

Polycystic ovarian syndrome (PCOS) is a complex endocrinopathy in women of reproductive age and the main cause of female infertility, but there is no universal drug for PCOS therapy. As a predominant dietary isoflavone present in soybeans, genistein (GEN) possesses estrogenic and antioxidative properties, but limited information is available regarding its therapeutic potential and underlying molecular mechanism in PCOS. In this study, we found that GEN might restore the estrous cycle of PCOS mice and ameliorate the elevation of circulating T, AMH and LH levels as well as LH/FSH ratios along with reduced cystic follicles, indicating the importance of GEN in PCOS therapy. Meanwhile, GEN improved the ovarian secretion function of PCOS mice and attenuated oxidative damage of the ovary through enhancing its antioxidant capability dependent on ER. Supplementation of GEN improved the defect of the ATP level and mitochondrial membrane potential, indicating the significance of GEN in preventing mitochondrial dysfunction. Further analysis demonstrated that GEN via ER heightened the expression of Nrf2 and Foxo1 whose blockage antagonized the defence of GEN on the secretory and mitochondrial functions of ovarian granulosa cells followed by the limited antioxidant capability and increased intracellular ROS level. Moreover, nuclear translocation and transcriptional activity of Nrf2 presented a notable enhancement after exposure to GEN. Addition of the Nrf2 inhibitor ML385 hampered the GEN induction of Foxo1. Nrf2 might directly bind to the antioxidant response element of the Foxo1 promoter region. Collectively, GEN might exhibit therapeutic potential for PCOS mice via the ER-Nrf2-Foxo1-ROS pathway.

Bmp2 regulates Serpinb6b expression via cAMP/PKA/Wnt4 pathway during uterine decidualization.

Serpinb6b is a novel member of Serpinb family and found in germ and somatic cells of mouse gonads, but its physiological function in uterine decidualization remains unclear. The present study revealed that abundant Serpinb6b was noted in decidual cells, and advanced the proliferation and differentiation of stromal cells, indicating a creative role of Serpinb6b in uterine decidualization. Further analysis found that Serpinb6b modulated the expression of Mmp2 and Mmp9. Meanwhile, Serpinb6b was identified as a target of Bmp2 regulation in stromal differentiation. Treatment with rBmp2 resulted in an accumulation of intracellular cAMP level whose function in this differentiation program was mediated by Serpinb6b. Addition of PKA inhibitor H89 impeded the Bmp2 induction of Serpinb6b, whereas 8-Br-cAMP rescued the defect of Serpinb6b expression elicited by Bmp2 knock-down. Attenuation of Serpinb6b greatly reduced the induction of constitutive Wnt4 activation on stromal cell differentiation. By contrast, overexpression of Serpinb6b prevented this inhibition of differentiation process by Wnt4 siRNA. Moreover, blockage of Wnt4 abrogated the up-regulation of cAMP on Serpinb6b. Collectively, Serpinb6b mediates uterine decidualization via Mmp2/9 in response to Bmp2/cAMP/PKA/Wnt4 pathway.

Malic enzyme 1 is important for uterine decidualization in response to progesterone/cAMP/PKA/HB-EGF pathway.

Malic enzyme 1 (Me1), a member of the malic enzymes involving in glycolytic pathway and citric acid cycle, is essential for the energy metabolism and maintenance of intracellular redox balance state, but its physiological role and regulatory mechanism in the uterine decidualization are still unknown. Current study showed that Me1 was strongly expressed in decidual cells, and could promote the proliferation and differentiation of stromal cells followed by an accelerated cell cycle transition, indicating an importance of Me1 in the uterine decidualization. Silencing of Me1 attenuated NADPH generation and reduced GR activity, while addition of NADPH improved the defect of GR activity elicited by Me1 depletion. Further analysis found that Me1 modulated intracellular GSH content via GR. Meanwhile, Me1 played a role in maintaining mitochondrial function as indicated by these observations that blockadge of Me1 led to the accumulation of mitochondrial O2- level and decreased ATP production and mtDNA copy numbers accompanied with defective mitochondrial membrane potential. In uterine stromal cells, progesterone induced Me1 expression through PR-cAMP-PKA pathway. Knockdown of HB-EGF might impede the regulation of progesterone and cAMP on Me1. Collectively, Me1 is essential for uterine decidualization in response to progesterone/cAMP/PKA/HB-EGF pathway and plays an important role in preventing mitochondrial dysfunction.

Novel insights into Dhh signaling in antler chondrocyte proliferation and differentiation: Involvement of Foxa.

The desert hedgehog (Dhh) is crucial for spermatogenesis and Leydig cell differentiation, but little is known regarding its physiological function in cartilage. In this study, Dhh mRNA was abundant in antler chondrocytes, where it advanced cell proliferation concomitant with accelerated transition from the G1 to the S phase and induced elevation of the hypertrophic chondrocyte markers, Col X and Runx2. Silencing of Ptch1 resulted in appreciable Smo accumulation and enhanced rDhh stimulation of Smo, whose impediment by cyclopamine obscured the proliferative function of Dhh and alleviated its guidance of chondrocyte differentiation. Further analysis evidenced the noteworthy positive action of Smo in the bridging between Dhh and Gli transcription factors. Obstruction of Gli1 by GANT58 caused the failed stimulation of Col X and Runx2 by rDhh. Analogously, siRNA against Gli1-3 hindered chondrocyte differentiation in the context of rDhh. Simultaneously, Gli transcription factors mediated the regulation of Dhh on Foxa1, Foxa2, and Foxa3, whose knockdown impaired chondrocyte differentiation. Attenuation of Foxa antagonized the augmentation of Col X and Runx2 generated by rDhh. Collectively, Dhh signaling through its target Foxa appears to induce antler chondrocyte proliferation and differentiation.

Genistein protects ovarian granulosa cells from oxidative stress via cAMP-PKA signaling.

Genistein is an isoflavone that has estrogen (E2 )-like activity and is beneficial for follicular development, but little is known regarding its function in oxidative stress (OS)-mediated granulosa cell (GC) injury. Here, we found that after exposure to H2 O2 , Genistein weakened the elevated levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA), which were regarded as the biomarkers for OS, and rescued glutathione (GSH) content and GSH/GSSG ratio accompanying with a simultaneous increase in cyclic adenosine monophosphate (cAMP) level, whereas addition of protein kinase A (PKA) inhibitor H89 impeded the effects of Genistein on the levels of ROS and MDA. Further analysis evidenced that Genistein enhanced the activities of antioxidant enzymes superoxide dismutase (SOD), GSH-peroxidase (GSH-Px), and catalase (CAT) in H2 O2 -treated GCs, but this enhancement was attenuated by H89. Under OS, Genistein improved cell viability and lessened the apoptotic rate of GCs along with a reduction in the activity of Casp3 and levels of Bax and Bad messenger RNA (mRNA), while H89 reversed the above effects. Moreover, Genistein treatment caused an obvious elevation in mitochondrial membrane potential (MMP) followed by a decline in the levels of intracellular mitochondrial superoxide, but H89 inhibited the regulation of Genistein on MMP and mitochondrial superoxide. Supplementation of Genistein promoted the secretion of E2 and increased the expression of Star and Cyp19a1 mRNA, whereas suppressed the level of progesterone (P4 ) accompanied with a decline in the level of Hsd3b1 mRNA expression. H89 blocked the regulation of Genistein on the secretion of E2 and P4 , and alleviated the ascending of Star and Cyp19a1 elicited by Genistein. Collectively, Genistein protects GCs from OS via cAMP-PKA signaling.

Hydroxysafflor yellow A exerts beneficial effects by restoring hormone secretion and alleviating oxidative stress in polycystic ovary syndrome mice.

NEW FINDINGS: What is the central question of this study? What are the potential therapeutic roles of ginsenoside Rb1 and hydroxysafflor yellow A (HSYA) in polycystic ovary syndrome (PCOS). What is the main finding and its importance? HSYA restored the oestrous cycles of PCOS mice, reduced follicular cysts in ovaries and rescued abnormal hormone secretion; ginsenoside Rb1 did not ameliorate the main symptoms of PCOS mice. HSYA alleviated oxidative stress along with an enhancement of antioxidant enzyme activity. This highlights a potential role of HSYA in PCOS therapy. ABSTRACT: Polycystic ovary syndrome (PCOS) is the most common endocrine disease resulting in female infertility. Hydroxysafflor yellow A (HSYA) and ginsenoside Rb1 have been shown to have antioxidant properties, but little is known about their impact in PCOS. Here dehydroepiandrosterone was used to induce PCOS in a mouse model that was characterized by an irregular oestrous cycle, cystic follicles and an elevated serum testosterone level. Supplementation of HSYA restored the oestrous cycle of PCOS mice, reduced follicular cysts in PCOS mouse ovaries and brought about a decline in serum testosterone level, while ginsenoside Rb1 did not ameliorate the above symptoms of PCOS mice. After HSYA treatment, there was elevation of serum oestradiol, progesterone, luteinizing hormone and anti-Müllerian hormone levels and a reduction of follicle-stimulating hormone level, but ginsenoside Rb1 only rescued the levels of follicle-stimulating hormone and anti-Müllerian hormone. Further analysis evidenced that HSYA reversed the expression of steroid hormone secretion-related genes Star, Hsd3b1, Cyp11a1 and Cyp19a1. In PCOS mice HSYA weakened the elevation of ovarian malondialdehyde, which is regarded as a biomarker for oxidative stress. Moreover, HSYA improved reduced glutathione content accompanied by a simultaneous increase in reduced to oxidized glutathione ratio, and enhanced the activities of the antioxidant enzymes superoxide dismutase, glutathione peroxidase and catalase. Collectively, HSYA exerted beneficial effects on PCOS mice by restoring hormone secretion and alleviating oxidative stress.

HB-EGF Ameliorates Oxidative Stress-Mediated Uterine Decidualization Damage.

HB-EGF is essential for uterine decidualization, but its antioxidant function remains largely unclear. Here, we found that HB-EGF promoted the proliferation of stromal cells followed by the accelerated transition of the cell cycle from G1 to S phase and enhanced the expression or activity of Prl8a2, Prl3c1, and ALP which were well-established markers for uterine stromal cell differentiation during decidualization. Under oxidative stress, stromal cell differentiation was impaired, but this impairment was abrogated by rHB-EGF accompanied with the reduced levels of ROS and MDA which were regarded as the biomarkers for oxidative stress, indicating an antioxidant role of HB-EGF. Further analysis revealed that HB-EGF enhanced the activities of antioxidant enzymes SOD, CAT, and GPX, where addition of GPX inhibitor MS attenuated the induction of rHB-EGF on Prl8a2, Prl3c1, and ALP. Meanwhile, HB-EGF rescued the content of GSH and restored the ratio of GSH/GSSG after exposure to H2O2 but did not alter NOX activity. Along with a decline for mitochondrial superoxide, exogenous rHB-EGF improved the damage of oxidative stress on mtDNA copy number, ATP level, mitochondrial membrane potential, and activities of mitochondrial respiratory chain complex I and III whose blockage by ROT and AA led to a failure of rHB-EGF in protecting stromal cell differentiation against injury. Moreover, HB-EGF prevented stromal cell apoptosis by inhibiting Caspase-3 activity and Bax expression and recovering the level of Bcl-2 mRNA. Collectively, HB-EGF might ameliorate oxidative stress-mediated uterine decidualization damage.

Function and regulation of transforming growth factor ß1 signalling in antler chondrocyte proliferation and differentiation.

OBJECTIVES: Chondrocyte proliferation and differentiation are crucial for endochondral ossification, but their regulatory mechanism remains unclear. The present study aimed to determine the physiological function of TGFß1 signalling in the proliferation and differentiation of antler chondrocytes and explore its relationship with Notch, Shh signalling and Foxa. MATERIALS AND METHODS: Immunofluorescence, Western blot, MTS assay, flow cytometry, RNA interference and real-time PCR were used to analyse the function and regulatory mechanisms of TGFß1 signalling in antler chondrocyte proliferation and differentiation. RESULTS: TGFß1, TGFBR1 and TGFBR2 were highly expressed in antler cartilage. TGFß1 promoted chondrocyte proliferation, increased the proportion of S-phase cells and induced the expression of hypertrophic chondrocyte markers Col X, Runx2 and Alpl. However, this induction was weakened by TGFß receptor inhibitor SB431542 and Smad3 inhibitor SIS3. Simultaneously, TGFß1 activated Notch and Shh signalling whose blockage attenuated the above effects of rTGFß1, whereas addition of rShh rescued the defects in chondrocyte proliferation and differentiation elicited by SB431542 and SIS3. Further analysis revealed that inhibition of Notch signalling impeded TGFß1 activation of the Shh pathway. Knockdown of Foxa1, Foxa2 and Foxa3 abrogated the effects of TGFß1 on chondrocyte differentiation. Notch and Shh signalling mediated the regulation of Foxa transcription factors by TGFß1. CONCLUSIONS: TGFß1 signalling could induce the proliferation and differentiation of antler chondrocytes through Notch-Shh-Foxa pathway.

Crosstalk between Activin A and Shh signaling contributes to the proliferation and differentiation of antler chondrocytes.

Chondrocyte proliferation and differentiation are crucial for endochondral ossification and strictly regulated by numerous signaling molecules and transcription factors, but the hierarchical regulatory network remains to be deciphered. The present study emphasized the interplay of Activin A, Foxa, Notch and Shh signaling in the proliferation and differentiation of antler chondrocytes. We found that Activin A promoted chondrocyte proliferation and differentiation, and accelerated the transition of cell cycle from G1 into S phase along with the activation of Notch and Shh signaling whose blockage attenuated above function of Activin A. Inhibition of Notch pathway by DAPT led to a significant reduction in the expression of Shh signaling molecules, whereas addition of exogenous rShh rescued the delayed onset of chondrocyte proliferation and differentiation elicited by DAPT, indicating that Notch pathway is upstream of Shh signaling. Further analysis evidenced that DAPT attenuated the activation of Activin A on Shh signaling. Simultaneously, Foxa transcription factors were downstream targets of Shh signaling in chondrocyte differentiation. Moreover, Shh pathway played an important role in the crosstalk between Activin A-Notch signaling and Foxa. Collectively, Shh signaling may act downstream of Notch pathway to mediate the effects of Activin A on the proliferation and differentiation of antler chondrocytes through targeting Foxa.

Hmgb3 Induces the Differentiation of Uterine Stromal Cells Through Targeting Ptn.

Uterine decidualization is crucial for placenta formation and pregnancy maintenance. Although previous studies have reported that high mobility group box 3 (Hmgb3) is involved in the regulation of cellular proliferation and differentiation, little is known regarding its physiological role in uterine decidualization. Here, in situ hybridization result exhibited a dynamic expression pattern of Hmgb3 messenger RNA (mRNA) during early gestation, and it was mainly localized to the decidua on days 6 to 8 of gestation. Consistently, elevated Hmgb3 expression was noted in the decidualizing stromal cells after intraluminal oil infusion. In uterine luminal epithelium of ovariectomized mice, estrogen induced the accumulation of Hmgb3 mRNA, which was dependent on the existence of implanting blastocyst. Simultaneously, Hmgb3 could stimulate the proliferation of uterine stromal cells and promote the expression of Prl8a2, a reliable marker for stromal cell differentiation. Further analysis evidenced that Hmgb3 might modulate the expression of pleiotropin (Ptn) in uterine stromal cells. Moreover, silencing of Ptn could impede the upregulation of Prl8a2 elicited by Hmgb3 overexpression, while overexpression of Ptn reversed the repressive effects of Hmgb3 siRNA on Prl8a2 expression. Collectively, Hmgb3 may direct uterine decidualization through targeting Ptn.

High Mobility Group Box 1 Regulates Uterine Decidualization through Bone Morphogenetic Protein 2 and Plays a Role in Kruppel-Like Factor 5-Induced Stromal Differentiation.

BACKGROUND/AIMS: High mobility group box 1 (Hmgb1) is associated with a variety of physiological processes including embryonic development, cell proliferation and differentiation, but little information is available regarding its biological role in decidualization. METHODS: In situ hybridization, real-time PCR, RNA interference, gene overexpression and MTS assay were used to analyze the spatiotemporal expression of Hmgb1 in mouse uterus during the pre-implantation period, and explore its function and regulatory mechanisms during uterine decidualization. RESULTS: Hmgb1 mRNA was obviously observed in uterine epithelium on day 2 and 3 of pregnancy, but its expression was scarcely detected on day 4 of pregnancy. With the onset of embryo implantation, abundant Hmgb1 expression was noted in the subluminal stromal cells around the implanting blastocyst at implantation sites. Meanwhile, the accumulation of Hmgb1 mRNA was visualized in the decidual cells. Hmgb1 advanced the proliferation of uterine stromal cells and induced the expression of prolactin family 8, subfamily a, member 2 (Prl8a2), a reliable differentiation marker for decidualization. In uterine stromal cells, cAMP analogue 8-Br-cAMP up-regulated the expression of Hmgb1, but the up-regulation was abrogated by protein kinase A (PKA) inhibitor H89. Silencing of Hmgb1 by specific siRNA impeded the induction of 8-Br-cAMP on Prl8a2. Further analysis evidenced that Hmgb1 was a critical mediator of Kruppel-like factor 5 (Klf5) function in stromal differentiation. Knockdown of bone morphogenetic protein 2 (Bmp2) prevented the up-regulation of Prl8a2 elicited by Hmgb1 overexpression, whereas addition of exogenous recombinant Bmp2 protein (rBmp2) reversed the repression of Hmgb1 siRNA on Prl8a2 expression. CONCLUSION: Hmgb1 may play an important role during mouse uterine decidualization.

Egr2 mediates the differentiation of mouse uterine stromal cells responsiveness to HB-EGF during decidualization.

Although Egr2 is involved in regulating the folliculogenesis and ovulation, there is almost no data describing its physiological function in embryo implantation and decidualization. Here, we showed that Egr2 mRNA was distinctly accumulated in subluminal stromal cells around implanting blastocyst on day 5 of pregnancy as well as in estrogen-activated implantation uterus. Estrogen induced the expression of Egr2 in uterine epithelia. Elevated expression of Egr2 mRNA was also observed in the decidual cells. Silencing of Egr2 by specific siRNA weakened the proliferation of uterine stromal cells and reduced the expression of Ccnd1, Ccnd3, Cdk4, and Cdk6. Furthermore, Egr2 advanced the expression of Prl8a2, Prl3c1, and Pgr, the well-established differentiation markers for decidualization. Administration of exogenous recombinant heparin-binding EGF-like growth factor (rHB-EGF) to uterine stromal cells resulted in an increase in the level of Egr2 mRNA. Moreover, siRNA-mediated attenuation of Egr2 impeded the stimulation of HB-EGF on stromal cell differentiation. Knockdown of Egr2 led to a reduction in the expression of Cox-2, mPGES-1, Vegf, Trp53, and Mmp2. Further analysis found that Egr2 may serve as an intermediate to mediate the regulation of HB-EGF on Cox-2, mPGES-1, Vegf, Trp53, Mmp2, and Ccnd3. Collectively, Egr2 may play an important role during embryo implantation and decidualization.

WNT4 acts downstream of BMP2 to mediate the regulation of ATRA signaling on RUNX1 expression: Implications for terminal differentiation of antler chondrocytes.

Although ATRA is involved in regulating the proliferation and differentiation of chondrocytes, its underlying mechanism remains unknown. Here we showed that ATRA could stimulate the proliferation of antler chondrocytes and expression of COL X and MMP13 which were two well-known markers for hypertrophic chondrocytes. Silencing of CRABP2 prevented the induction of ATRA on chondrocyte terminal differentiation, while overexpression of CRABP2 exhibited the opposite effects. CYP26A1 and CYP26B1 weakened the sensitivity of antler chondrocytes to ATRA. Further analysis evidenced that ATRA might induce chondrocyte terminal differentiation and modulate the expression of BMP2, WNT4, and RUNX1 through RARα/RXRα. Knockdown of BMP2 enhanced the induction of ATRA on the expression of COL X and MMP13, whereas overexpression of BMP2 abrogated this effectiveness. WNT4 might mediate the effects of ATRA and BMP2 on chondrocyte terminal differentiation. Dysregulation of BMP2 impaired the regulation of ATRA on WNT4 expression. Administration of ATRA to antler chondrocytes transfected with RUNX1 siRNA failed to induce the differentiation. Conversely, rRUNX1 strengthened the stimulation of ATRA on the expression of COL X and MMP13. Simultaneously, RUNX1 was a downstream effector of BMP2 and WNT4 in chondrocyte terminal differentiation. Moreover, WNT4 might play an important role in the crosstalk between BMP2 and RUNX1. Attenuation of BMP2 or WNT4 enhanced the interaction between ATRA and RUNX1, while constitutive expression of BMP2 or WNT4 reversed the regulation of ATRA on RUNX1. Collectively, WNT4 may act downstream of BMP2 to mediate the effects of ATRA on the terminal differentiation of antler chondrocytes through targeting RUNX1.

Ptn functions downstream of C/EBPß to mediate the effects of cAMP on uterine stromal cell differentiation through targeting Hand2 in response to progesterone.

Ptn is a pleiotropic growth factor involving in the regulation of cellular proliferation and differentiation, but its biological function in uterine decidualization remains unknown. Here, we showed that Ptn was highly expressed in the decidual cells, and could induce the proliferation of uterine stromal cells and expression of Prl8a2 and Prl3c1 which were two well-established differentiation markers for decidualization, suggesting an important role of Ptn in decidualization. In the uterine stromal cells, progesterone stimulated the expression of Ptn accompanied with an accumulation of intracellular cAMP level. Silencing of Ptn impeded the induction of progesterone and cAMP on the differentiation of uterine stromal cells. Administration of PKA inhibitor H89 resulted in a blockage of progesterone on Ptn expression. Further analysis evidenced that regulation of progesterone and cAMP on Ptn was mediated by C/EBPß. During in vitro decidualization, knockdown of Ptn could weaken the up-regulation of Prl8a2 and Prl3c1 elicited by C/EBPß overexpression, while constitutive activation of Ptn reversed the repressive effects of C/EBPß siRNA on the expression of Prl8a2 and Prl3c1. Meanwhile, Ptn might mediate the regulation of C/EBPß on Hand2 which was a downstream target of Ptn in the differentiation of uterine stromal cells. Attenuation of Ptn or C/EBPß by specific siRNA blocked the stimulation of Hand2 by progesterone and cAMP. Collectively, Ptn may play a vital role in the progesterone-induced decidualization pathway.

Evidence For Hmgn2 Involvement in Mouse Embryo Implantation and Decidualization.

BACKGROUND/AIMS: Hmgn2 is involved in regulating embryonic development, but its physiological function during embryo implantation and decidualization remains unknown. METHODS: In situ hybridization, real-time PCR, RNA interference, gene overexpression and MTS assay were used to examine the expression of Hmgn2 in mouse uterus during the pre-implantation period and explore its function and regulatory mechanisms in epithelial adhesion junction and stromal cell proliferation and differentiation. RESULTS: Hmgn2 was primarily accumulated in uterine luminal epithelia on day 4 of pregnancy and subluminal stromal cells around the implanting blastocyst at implantation sites on day 5. Similar results were observed during delayed implantation and activation. Meanwhile, Hmgn2 expression was visualized in the decidua. In uterine epithelial cells, silencing of Hmgn2 by specific siRNA reduced the expression of adhesion molecules Cdh1, Cdh2 and Ctnnb1 and enhanced the expression of Muc1, whereas constitutive activation of Hmgn2 exhibited the opposite effects, suggesting a role for Hmgn2 in attachment reaction during embryo implantation. Estrogen stimulated the expression of Hmgn2 in uterine epithelia, but the stimulation was abrogated by ER antagonist ICI 182,780. Further analysis evidenced that attenuation of Hmgn2 might eliminate the regulation of estrogen on the expression of Cdh1, Cdh2 and Ctnnb1. In uterine stromal cells, progesterone induced the accumulation of Hmgn2 which advanced the expression of Prl8a2 and Prl3c1, two well-known differentiation markers for decidualization, but did not affect the proliferation of stromal cells. Knockdown of Hmgn2 blocked the progesterone-induced differentiation of uterine stromal cells. Moreover, Hmgn2 might serve as an intermediate to mediate the regulation of progesterone on Hand2. CONCLUSION: Hmgn2 may play an important role during embryo implantation and decidualization.

ATRA Signaling Regulates the Expression of COL9A1 through BMP2-WNT4-RUNX1 Pathway in Antler Chondrocytes.

Although all-trans retinoic acid (ATRA) is involved in the regulation of cartilage growth and development, its regulatory mechanisms remain unknown. Here, we showed that ATRA could induce the expression of COL9A1 in antler chondrocytes. Silencing of cellular retinoic acid binding protein 2 (CRABP2) could impede the ATRA-induced upregulation of COL9A1, whereas overexpression of CRABP2 presented the opposite effect. RARα agonist Am80 induced the expression of COL9A1, whereas treatment with RARα antagonist Ro 41-5253 or RXRα small-interfering RNA (siRNA) caused an obvious blockage of ATRA on COL9A1. In antler chondrocytes, CYP26A1 and CYP26B1 weakened the sensitivity of ATRA to COL9A1. Simultaneously, Bone morphogenetic protein 2 (BMP2) and WNT4 mediated the regulation of ATRA on COL9A1 expression. Knockdown of WNT4 could abrogate the inhibitory effect of BMP2 overexpression on COL9A1. Conversely, constitutive expression of WNT4 reversed the upregulation of COL9A1 elicited by BMP2 siRNA. Together these data indicated that WNT4 might act downstream of BMP2 to mediate the effect of ATRA on COL9A1 expression. Further analysis evidenced that attenuation of runt-related transcription factor 1 (RUNX1) could prevent the stimulation of ATRA on COL9A1 expression, while exogenous rRUNX1 further enhanced this effectiveness. Moreover, RUNX1 might serve as an intermediate to mediate the regulation of BMP2 and WNT4 on COL9A1 expression. Collectively, ATRA signaling might regulate the expression of COL9A1 through BMP2-WNT4-RUNX1 pathway.

Gja1 acts downstream of Acvr1 to regulate uterine decidualization via Hand2 in mice.

Although Gja1 has been proved to play an important role in uterine decidualization, its regulatory mechanism remains largely unknown. Here, we showed that Gja1 was highly expressed in the decidual cells and promoted the proliferation of uterine stromal cells and expression of Prl8a2 and Prl3c1, which were two well-known differentiation markers for decidualization. Further analysis revealed that Gja1 might act downstream of Acvr1 and cAMP to regulate the differentiation of uterine stromal cells. Administration of cAMP analog 8-Br-cAMP to Acvr1 siRNA-transfected stromal cells resulted in an obvious increase of Gja1 expression, whereas PKA inhibitor H89 impeded the induction of Gja1 elicited by Acvr1 overexpression, indicating that cAMP-PKA signal mediates the regulation of Acvr1 on Gja1 expression. In uterine stromal cells, knockdown of Gja1 blocked the cAMP induction of Hand2 Moreover, siRNA-mediated downregulation of Hand2 impaired the stimulatory effects of Gja1 overexpression on the expression of Prl8a2 and Prl3c1, whereas constitutive expression of Hand2 reversed the inhibitory effects of Gja1 siRNA on stromal differentiation. Meanwhile, Gja1 might play a vital role in the crosstalk between Acvr1 and Hand2 Collectively, Gja1 may act downstream of cAMP-PKA signal to mediate the effects of Acvr1 on the differentiation of uterine stromal cells through targeting Hand2.