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Rac1 Regulates Endometrial Secretory Function to Control Placental Development.

Davila J, Laws MJ, Kannan A, Li Q, Taylor RN, Bagchi MK, Bagchi IC - PLoS Genet. (2015)

Bottom Line: Ablation of Rac1 did not affect the formation of the decidua but led to fetal loss in mid gestation accompanied by extensive hemorrhage.Consequently, the Rac1- decidual cells failed to secrete vascular endothelial growth factor A, which is a critical regulator of decidual angiogenesis, and insulin-like growth factor binding protein 4, which regulates the bioavailability of insulin-like growth factors that promote proliferation and differentiation of trophoblast cell lineages in the ectoplacental cone.The lack of secretion of these key factors by Rac1- decidua gave rise to impaired angiogenesis and dysregulated proliferation of trophoblast cells, which in turn results in overexpansion of the trophoblast giant cell lineage and disorganized placenta development.

View Article: PubMed Central - PubMed

Affiliation: Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.

ABSTRACT
During placenta development, a succession of complex molecular and cellular interactions between the maternal endometrium and the developing embryo ensures reproductive success. The precise mechanisms regulating this maternal-fetal crosstalk remain unknown. Our study revealed that the expression of Rac1, a member of the Rho family of GTPases, is markedly elevated in mouse decidua on days 7 and 8 of gestation. To investigate its function in the uterus, we created mice bearing a conditional deletion of the Rac1 gene in uterine stromal cells. Ablation of Rac1 did not affect the formation of the decidua but led to fetal loss in mid gestation accompanied by extensive hemorrhage. To gain insights into the molecular pathways affected by the loss of Rac1, we performed gene expression profiling which revealed that Rac1 signaling regulates the expression of Rab27b, another GTPase that plays a key role in targeting vesicular trafficking. Consequently, the Rac1- decidual cells failed to secrete vascular endothelial growth factor A, which is a critical regulator of decidual angiogenesis, and insulin-like growth factor binding protein 4, which regulates the bioavailability of insulin-like growth factors that promote proliferation and differentiation of trophoblast cell lineages in the ectoplacental cone. The lack of secretion of these key factors by Rac1- decidua gave rise to impaired angiogenesis and dysregulated proliferation of trophoblast cells, which in turn results in overexpansion of the trophoblast giant cell lineage and disorganized placenta development. Further experiments revealed that RAC1, the human ortholog of Rac1, regulates the secretory activity of human endometrial stromal cells during decidualization, supporting the concept that this signaling G protein plays a central and conserved role in controlling endometrial secretory function. This study provides unique insights into the molecular mechanisms regulating endometrial secretions that mediate stromal-endothelial and stromal-trophoblast crosstalk critical for placenta development and establishment of pregnancy.

No MeSH data available.


Related in: MedlinePlus

Early implantation is unaffected in Rac1 conditional knockout mouse.(A) Gross morphology of Rac1f/f and Rac1d/d uteri at days 6 and 8 of gestation. (B)Rac1f/f and Rac1d/d mice were subjected to artificial decidual stimulation for 96 hours as described in the Materials and methods. For each mouse, one uterine horn was stimulated, while the other horn was left undisturbed. Gross morphology of Rac1f/f and Rac1d/d uteri following the application of the decidual stimulus is shown. (C) Comparative wet weight gains in uteri of Rac1f/f and Rac1d/d mice. Following artificial decidualization, stimulated and unstimulated horns were assessed for wet weight gain. The histogram shows the ratios of average weights of stimulated over unstimulated horns from Rac1f/f and Rac1d/d mice. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05). (D) Uterine sections from Rac1f/f and Rac1d/d mice on day 8 of pregnancy were subjected to alkaline phosphatase activity (ALPL, upper) and IF staining using an antibody specific for the prolactin-related protein (PRL82A, lower). AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (E) Comparable expressions of various markers of decidualization in Rac1f/f and Rac1d/d uteri. Total RNA was isolated from uteri on day 8 of pregnancy and qPCR analysis was performed using primers specific for Pgr, Bmp2, and Gja1. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05).
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pgen.1005458.g003: Early implantation is unaffected in Rac1 conditional knockout mouse.(A) Gross morphology of Rac1f/f and Rac1d/d uteri at days 6 and 8 of gestation. (B)Rac1f/f and Rac1d/d mice were subjected to artificial decidual stimulation for 96 hours as described in the Materials and methods. For each mouse, one uterine horn was stimulated, while the other horn was left undisturbed. Gross morphology of Rac1f/f and Rac1d/d uteri following the application of the decidual stimulus is shown. (C) Comparative wet weight gains in uteri of Rac1f/f and Rac1d/d mice. Following artificial decidualization, stimulated and unstimulated horns were assessed for wet weight gain. The histogram shows the ratios of average weights of stimulated over unstimulated horns from Rac1f/f and Rac1d/d mice. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05). (D) Uterine sections from Rac1f/f and Rac1d/d mice on day 8 of pregnancy were subjected to alkaline phosphatase activity (ALPL, upper) and IF staining using an antibody specific for the prolactin-related protein (PRL82A, lower). AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (E) Comparable expressions of various markers of decidualization in Rac1f/f and Rac1d/d uteri. Total RNA was isolated from uteri on day 8 of pregnancy and qPCR analysis was performed using primers specific for Pgr, Bmp2, and Gja1. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05).

Mentions: Gross examination of uterine morphology revealed apparently normal embryonic implantation sites in Rac1f/f and Rac1d/d uteri on days 6 and 8 of pregnancy (Fig 3A). There was no apparent defect in uterine receptivity, embryo attachment and formation of decidual mass in pregnant Rac1d/d uteri. To further analyze the decidual response in Rac1d/d females, we performed experimentally induced decidualization. As shown in Fig 3B, both Rac1f/f and Rac1d/d uteri exhibited robust decidual responses upon stimulation. When the decidual responses were assessed by measurement of uterine wet weight gain, there was no significant difference between Rac1f/f and Rac1d/d uteri (Fig 3C). Consistent with these observations, the expression of prolactin-related protein (PRL8A2/dPRP) and alkaline phosphatase (ALPL), known biomarkers of decidualization [28–31] was comparable in the uterine sections of Rac1f/f and Rac1d/d mice on day 8 of pregnancy (Fig 3D). We additionally examined the expression of a panel of factors, Pgr, Bmp2 and Gja1 (Cx43), which are known regulators of decidualization in mice [20, 25, 31, 32]. Our studies showed that the expression of Pgr, Bmp2, and Gja1 mRNAs remained unaffected by the loss of uterine Rac1, indicating that at least certain aspects of the decidualization process progresses normally in Rac1d/d uteri (Fig 3E).


Rac1 Regulates Endometrial Secretory Function to Control Placental Development.

Davila J, Laws MJ, Kannan A, Li Q, Taylor RN, Bagchi MK, Bagchi IC - PLoS Genet. (2015)

Early implantation is unaffected in Rac1 conditional knockout mouse.(A) Gross morphology of Rac1f/f and Rac1d/d uteri at days 6 and 8 of gestation. (B)Rac1f/f and Rac1d/d mice were subjected to artificial decidual stimulation for 96 hours as described in the Materials and methods. For each mouse, one uterine horn was stimulated, while the other horn was left undisturbed. Gross morphology of Rac1f/f and Rac1d/d uteri following the application of the decidual stimulus is shown. (C) Comparative wet weight gains in uteri of Rac1f/f and Rac1d/d mice. Following artificial decidualization, stimulated and unstimulated horns were assessed for wet weight gain. The histogram shows the ratios of average weights of stimulated over unstimulated horns from Rac1f/f and Rac1d/d mice. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05). (D) Uterine sections from Rac1f/f and Rac1d/d mice on day 8 of pregnancy were subjected to alkaline phosphatase activity (ALPL, upper) and IF staining using an antibody specific for the prolactin-related protein (PRL82A, lower). AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (E) Comparable expressions of various markers of decidualization in Rac1f/f and Rac1d/d uteri. Total RNA was isolated from uteri on day 8 of pregnancy and qPCR analysis was performed using primers specific for Pgr, Bmp2, and Gja1. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05).
© Copyright Policy
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Show All Figures
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pgen.1005458.g003: Early implantation is unaffected in Rac1 conditional knockout mouse.(A) Gross morphology of Rac1f/f and Rac1d/d uteri at days 6 and 8 of gestation. (B)Rac1f/f and Rac1d/d mice were subjected to artificial decidual stimulation for 96 hours as described in the Materials and methods. For each mouse, one uterine horn was stimulated, while the other horn was left undisturbed. Gross morphology of Rac1f/f and Rac1d/d uteri following the application of the decidual stimulus is shown. (C) Comparative wet weight gains in uteri of Rac1f/f and Rac1d/d mice. Following artificial decidualization, stimulated and unstimulated horns were assessed for wet weight gain. The histogram shows the ratios of average weights of stimulated over unstimulated horns from Rac1f/f and Rac1d/d mice. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05). (D) Uterine sections from Rac1f/f and Rac1d/d mice on day 8 of pregnancy were subjected to alkaline phosphatase activity (ALPL, upper) and IF staining using an antibody specific for the prolactin-related protein (PRL82A, lower). AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (E) Comparable expressions of various markers of decidualization in Rac1f/f and Rac1d/d uteri. Total RNA was isolated from uteri on day 8 of pregnancy and qPCR analysis was performed using primers specific for Pgr, Bmp2, and Gja1. Data represent mean ± SEM from four separate samples and were analyzed by t-test, P > 0.05).
Mentions: Gross examination of uterine morphology revealed apparently normal embryonic implantation sites in Rac1f/f and Rac1d/d uteri on days 6 and 8 of pregnancy (Fig 3A). There was no apparent defect in uterine receptivity, embryo attachment and formation of decidual mass in pregnant Rac1d/d uteri. To further analyze the decidual response in Rac1d/d females, we performed experimentally induced decidualization. As shown in Fig 3B, both Rac1f/f and Rac1d/d uteri exhibited robust decidual responses upon stimulation. When the decidual responses were assessed by measurement of uterine wet weight gain, there was no significant difference between Rac1f/f and Rac1d/d uteri (Fig 3C). Consistent with these observations, the expression of prolactin-related protein (PRL8A2/dPRP) and alkaline phosphatase (ALPL), known biomarkers of decidualization [28–31] was comparable in the uterine sections of Rac1f/f and Rac1d/d mice on day 8 of pregnancy (Fig 3D). We additionally examined the expression of a panel of factors, Pgr, Bmp2 and Gja1 (Cx43), which are known regulators of decidualization in mice [20, 25, 31, 32]. Our studies showed that the expression of Pgr, Bmp2, and Gja1 mRNAs remained unaffected by the loss of uterine Rac1, indicating that at least certain aspects of the decidualization process progresses normally in Rac1d/d uteri (Fig 3E).

Bottom Line: Ablation of Rac1 did not affect the formation of the decidua but led to fetal loss in mid gestation accompanied by extensive hemorrhage.Consequently, the Rac1- decidual cells failed to secrete vascular endothelial growth factor A, which is a critical regulator of decidual angiogenesis, and insulin-like growth factor binding protein 4, which regulates the bioavailability of insulin-like growth factors that promote proliferation and differentiation of trophoblast cell lineages in the ectoplacental cone.The lack of secretion of these key factors by Rac1- decidua gave rise to impaired angiogenesis and dysregulated proliferation of trophoblast cells, which in turn results in overexpansion of the trophoblast giant cell lineage and disorganized placenta development.

View Article: PubMed Central - PubMed

Affiliation: Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.

ABSTRACT
During placenta development, a succession of complex molecular and cellular interactions between the maternal endometrium and the developing embryo ensures reproductive success. The precise mechanisms regulating this maternal-fetal crosstalk remain unknown. Our study revealed that the expression of Rac1, a member of the Rho family of GTPases, is markedly elevated in mouse decidua on days 7 and 8 of gestation. To investigate its function in the uterus, we created mice bearing a conditional deletion of the Rac1 gene in uterine stromal cells. Ablation of Rac1 did not affect the formation of the decidua but led to fetal loss in mid gestation accompanied by extensive hemorrhage. To gain insights into the molecular pathways affected by the loss of Rac1, we performed gene expression profiling which revealed that Rac1 signaling regulates the expression of Rab27b, another GTPase that plays a key role in targeting vesicular trafficking. Consequently, the Rac1- decidual cells failed to secrete vascular endothelial growth factor A, which is a critical regulator of decidual angiogenesis, and insulin-like growth factor binding protein 4, which regulates the bioavailability of insulin-like growth factors that promote proliferation and differentiation of trophoblast cell lineages in the ectoplacental cone. The lack of secretion of these key factors by Rac1- decidua gave rise to impaired angiogenesis and dysregulated proliferation of trophoblast cells, which in turn results in overexpansion of the trophoblast giant cell lineage and disorganized placenta development. Further experiments revealed that RAC1, the human ortholog of Rac1, regulates the secretory activity of human endometrial stromal cells during decidualization, supporting the concept that this signaling G protein plays a central and conserved role in controlling endometrial secretory function. This study provides unique insights into the molecular mechanisms regulating endometrial secretions that mediate stromal-endothelial and stromal-trophoblast crosstalk critical for placenta development and establishment of pregnancy.

No MeSH data available.


Related in: MedlinePlus