Limits...
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

Rac1 regulates vesicular exocytosis in decidual cells by controlling Rab27b.(A & B) Expression of Rab27b mRNA and protein is downregulated in Rac1- stromal cells. (A) qPCR was performed to monitor the expression of Rab27a and Rab27b in the uteri of Rac1f/f and Rac1d/d mice on day 8 of pregnancy. Data represent mean ± SEM from four separate samples and were analyzed by t-test. Asterisks indicate statistically significant differences (***P < 0.001). (B) IF of RAB27B in Rac1f/f and Rac1d/d uteri on day 8 of pregnancy. AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (C & D) Secretions by decidual cells are reduced in the conditioned media of Rac1- stromal cells. Stromal cells isolated from Rac1f/f and Rac1d/d uteri on day 4 of pregnancy were cultured for 96 hours, fixed and subjected to IF using VEGFA (C, Left) and IGFBP4 (D, Left) antibodies. Conditioned media from cultured stromal cells isolated from Rac1f/f and Rac1d/d uteri were analyzed for VEGFA (C, Right) and IGFBP4 (D, Right) by ELISA. Data represent mean ± SEM from three separate samples and were analyzed by two-way ANOVA with Bonferroni post-test. Asterisks indicate statistically significant differences (*P < 0.05, **P < 0.01, and ***P < 0.001).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4549291&req=5

pgen.1005458.g007: Rac1 regulates vesicular exocytosis in decidual cells by controlling Rab27b.(A & B) Expression of Rab27b mRNA and protein is downregulated in Rac1- stromal cells. (A) qPCR was performed to monitor the expression of Rab27a and Rab27b in the uteri of Rac1f/f and Rac1d/d mice on day 8 of pregnancy. Data represent mean ± SEM from four separate samples and were analyzed by t-test. Asterisks indicate statistically significant differences (***P < 0.001). (B) IF of RAB27B in Rac1f/f and Rac1d/d uteri on day 8 of pregnancy. AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (C & D) Secretions by decidual cells are reduced in the conditioned media of Rac1- stromal cells. Stromal cells isolated from Rac1f/f and Rac1d/d uteri on day 4 of pregnancy were cultured for 96 hours, fixed and subjected to IF using VEGFA (C, Left) and IGFBP4 (D, Left) antibodies. Conditioned media from cultured stromal cells isolated from Rac1f/f and Rac1d/d uteri were analyzed for VEGFA (C, Right) and IGFBP4 (D, Right) by ELISA. Data represent mean ± SEM from three separate samples and were analyzed by two-way ANOVA with Bonferroni post-test. Asterisks indicate statistically significant differences (*P < 0.05, **P < 0.01, and ***P < 0.001).

Mentions: We next investigated whether Rac1 signaling in the decidual cells exerts paracrine effects on the trophoblast cells during the early stages of placenta formation. Interestingly, our microarray analysis revealed that factors involved in vesicular trafficking are altered in Rac1- decidual cells (S2 Table). In particular, we observed a marked down-regulation of mRNAs corresponding to Rab27b, a member of the Rab27 subfamily of GTPases, which participate in membrane trafficking and thereby control protein secretion [17, 18, 36, 37]. This subfamily consists of two closely related homologs, Rab27a and Rab27b [17]. Rab27a is expressed in a wide variety of secretory cells and participates in the exocytosis of various secretory vesicles [17]. In contrast, Rab27b expression is much more restricted and presumably tightly regulated to allow the controlled release of vesicle contents in response to appropriate physiological signals [17, 18, 36]. As shown in Fig 7A, we observed downregulation of Rab27b mRNA, but not Rab27a mRNA, in uterine decidual cells of Rac1d/d mice on day 8 of gestation. Consistent with this finding, we noted a marked decline in the levels of Rab27B protein in the uterine sections of Rac1d/d mice (Fig 7B). Since the Rab27 proteins are known to control several steps in vesicular trafficking, including vesicle movement on tubulin cytoskeletal tracks, we considered the possibility that down-regulation of Rab27b expression in Rac1- uteri might affect secretory activity of the decidual cells.


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)

Rac1 regulates vesicular exocytosis in decidual cells by controlling Rab27b.(A & B) Expression of Rab27b mRNA and protein is downregulated in Rac1- stromal cells. (A) qPCR was performed to monitor the expression of Rab27a and Rab27b in the uteri of Rac1f/f and Rac1d/d mice on day 8 of pregnancy. Data represent mean ± SEM from four separate samples and were analyzed by t-test. Asterisks indicate statistically significant differences (***P < 0.001). (B) IF of RAB27B in Rac1f/f and Rac1d/d uteri on day 8 of pregnancy. AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (C & D) Secretions by decidual cells are reduced in the conditioned media of Rac1- stromal cells. Stromal cells isolated from Rac1f/f and Rac1d/d uteri on day 4 of pregnancy were cultured for 96 hours, fixed and subjected to IF using VEGFA (C, Left) and IGFBP4 (D, Left) antibodies. Conditioned media from cultured stromal cells isolated from Rac1f/f and Rac1d/d uteri were analyzed for VEGFA (C, Right) and IGFBP4 (D, Right) by ELISA. Data represent mean ± SEM from three separate samples and were analyzed by two-way ANOVA with Bonferroni post-test. Asterisks indicate statistically significant differences (*P < 0.05, **P < 0.01, and ***P < 0.001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4549291&req=5

pgen.1005458.g007: Rac1 regulates vesicular exocytosis in decidual cells by controlling Rab27b.(A & B) Expression of Rab27b mRNA and protein is downregulated in Rac1- stromal cells. (A) qPCR was performed to monitor the expression of Rab27a and Rab27b in the uteri of Rac1f/f and Rac1d/d mice on day 8 of pregnancy. Data represent mean ± SEM from four separate samples and were analyzed by t-test. Asterisks indicate statistically significant differences (***P < 0.001). (B) IF of RAB27B in Rac1f/f and Rac1d/d uteri on day 8 of pregnancy. AMD, MD, and E denote antimesometrial decidua, mesometrial decidua, and embryo respectively. (C & D) Secretions by decidual cells are reduced in the conditioned media of Rac1- stromal cells. Stromal cells isolated from Rac1f/f and Rac1d/d uteri on day 4 of pregnancy were cultured for 96 hours, fixed and subjected to IF using VEGFA (C, Left) and IGFBP4 (D, Left) antibodies. Conditioned media from cultured stromal cells isolated from Rac1f/f and Rac1d/d uteri were analyzed for VEGFA (C, Right) and IGFBP4 (D, Right) by ELISA. Data represent mean ± SEM from three separate samples and were analyzed by two-way ANOVA with Bonferroni post-test. Asterisks indicate statistically significant differences (*P < 0.05, **P < 0.01, and ***P < 0.001).
Mentions: We next investigated whether Rac1 signaling in the decidual cells exerts paracrine effects on the trophoblast cells during the early stages of placenta formation. Interestingly, our microarray analysis revealed that factors involved in vesicular trafficking are altered in Rac1- decidual cells (S2 Table). In particular, we observed a marked down-regulation of mRNAs corresponding to Rab27b, a member of the Rab27 subfamily of GTPases, which participate in membrane trafficking and thereby control protein secretion [17, 18, 36, 37]. This subfamily consists of two closely related homologs, Rab27a and Rab27b [17]. Rab27a is expressed in a wide variety of secretory cells and participates in the exocytosis of various secretory vesicles [17]. In contrast, Rab27b expression is much more restricted and presumably tightly regulated to allow the controlled release of vesicle contents in response to appropriate physiological signals [17, 18, 36]. As shown in Fig 7A, we observed downregulation of Rab27b mRNA, but not Rab27a mRNA, in uterine decidual cells of Rac1d/d mice on day 8 of gestation. Consistent with this finding, we noted a marked decline in the levels of Rab27B protein in the uterine sections of Rac1d/d mice (Fig 7B). Since the Rab27 proteins are known to control several steps in vesicular trafficking, including vesicle movement on tubulin cytoskeletal tracks, we considered the possibility that down-regulation of Rab27b expression in Rac1- uteri might affect secretory activity of the decidual cells.

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