scholarly journals Role and Regulation of Nodal/Activin Receptor-Like Kinase 7 Signaling Pathway in the Control of Ovarian Follicular Atresia

2006 ◽  
Vol 20 (10) ◽  
pp. 2469-2482 ◽  
Author(s):  
Hongmei Wang ◽  
Jin-Yi Jiang ◽  
Cheng Zhu ◽  
Chun Peng ◽  
Benjamin K. Tsang

Abstract Although the role of the TGF β superfamily members in the regulation of ovarian folliculogenesis has been extensively studied, their involvement in follicular atresia is not well understood. In the present study, we have demonstrated for the first time that Nodal, a member of the TGF β superfamily, is involved in promoting follicular atresia as evidenced by the following: 1) colocalization of Nodal and its type I receptor Activin receptor-like kinase 7 (ALK7) proteins in the granulosa cells was only observed in atretic antral follicles, whereas they were present in theca cells and granulosa cells of healthy follicles, respectively; 2) addition of recombinant Nodal or overexpression of Nodal by adenoviral infection induced apoptosis of otherwise healthy granulosa cells; 3) constitutively active ALK7 (ALK7-ca) overexpression mimicked the function of Nodal in the induction of granulosa cell apoptosis. Furthermore, overexpression of Nodal or ALK7-ca increased phosphorylation and nuclear translocation of Smad2, decreased X-linked inhibitor of apoptotic proteins (Xiap) expression at both mRNA and protein level and phospho-Akt content, as well as triggered mitochondrial release of death proteins Smac/DIABLO, Omi/HtrA2, and cytochrome c in the granulosa cells. Dominant-negative Smad2 significantly attenuated ALK7-ca-induced down-regulation of Xiap and thus rescued granulosa cells from undergoing apoptosis. In addition, whereas up-regulation of Xiap significantly attenuated ALK7-ca-induced apoptosis, down-regulation of Xiap sensitized granulosa cells to ALK7-ca-induced apoptosis. Furthermore, ALK7-ca-induced apoptosis was significantly attenuated by forced expression of activated Akt, and Akt rescued granulosa cells from undergoing apoptosis via proteasome-mediated ALK7 degradation. Taken together, Nodal plays an atretogenic role in the ovary where it induces granulosa cell apoptosis through activation of Smad2, down-regulation of the key survival molecules Xiap and phospho-Akt, as well as the activation of mitochondrial death pathway.

Endocrinology ◽  
2015 ◽  
Vol 156 (12) ◽  
pp. 4684-4694 ◽  
Author(s):  
Lanlan Fang ◽  
Hsun-Ming Chang ◽  
Jung-Chien Cheng ◽  
Yiping Yu ◽  
Peter C. K. Leung ◽  
...  

Growth differentiation factor-8 (GDF-8) has been recently shown to be expressed in human granulosa cells, and the mature form of GDF-8 protein can be detected in the follicular fluid. However, the biological function and significance of this growth factor in the human ovary remains to be determined. Here, we investigated the effects of GDF-8 on steroidogenic enzyme expression and the potential mechanisms of action in luteinized human granulosa cells. We demonstrated that treatment with GDF-8 did not affect the mRNA levels of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase, whereas it significantly down-regulated steroidogenic acute regulatory protein (StAR) expression and decreased progesterone production. The suppressive effect of GDF-8 on StAR expression was abolished by the inhibition of the TGF-β type I receptor. In addition, treatment with GDF-8 activated both Smad2/3 and ERK1/2 signaling pathways. Furthermore, knockdown of activin receptor-like kinase 5 reversed the effects of GDF-8 on Smad2/3 phosphorylation and StAR expression. The inhibition of Smad3 or ERK1/2 signaling pathways attenuated the GDF-8-induced down-regulation of StAR and production of progesterone. Interestingly, the concentrations of GDF-8 were negatively correlated with those of progesterone in human follicular fluid. These results indicate a novel autocrine function of GDF-8 to down-regulate StAR expression and decrease progesterone production in luteinized human granulosa cells, most likely through activin receptor-like kinase 5-mediated Smad3 and ERK1/2 signaling pathways. Our findings suggest that granulosa cells might play a critical role in the regulation of progesterone production to prevent premature luteinization during the final stage of folliculogenesis.


2021 ◽  
Vol 169 ◽  
pp. 47-55
Author(s):  
Xinyan Zhang ◽  
Tong Yu ◽  
Xinyan Guo ◽  
Ruixue Zhang ◽  
Yanni Jia ◽  
...  

PLoS ONE ◽  
2012 ◽  
Vol 7 (6) ◽  
pp. e38640 ◽  
Author(s):  
Fei Lin ◽  
Ran Li ◽  
Zeng xiang Pan ◽  
Bo Zhou ◽  
De bing Yu ◽  
...  

2007 ◽  
Vol 195 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Nina Renlund ◽  
Francis H O’Neill ◽  
LiHua Zhang ◽  
Yisrael Sidis ◽  
Jose Teixeira

Activin receptor-like kinase-2 (Alk2) has been shown to be a promiscuous type I receptor for the transforming growth factor β (TGFβ) family of growth and differentiation factors, such as activin, bone morphogenetic proteins, and Müllerian inhibiting substance (MIS). We have studied the putative role of Alk2 in activin signaling using MA-10 cells, a mouse transformed Leydig cell line, in which endogenous expression of cytochrome P450 c17 hydroxylase/C17–20 lyase mRNA is inhibited by both MIS and activin A. Overexpression of Alk2 in MA-10 cells inhibited the activation of the activin-responsive CAGA-luciferase reporter and, conversely, transfection of siRNA for Alk2 increased the response. In contrast, overexpression of the MIS type II receptor in MA-10 cells increased the activin-mediated induction of CAGA-luciferase approximately fivefold, which we hypothesized occurs by MIS type II receptor sequestering endogenous Alk2. Binding experiments with 125I-labeled activin show that the underlying mechanism of Alk2-mediated inhibition of activin signaling involves Alk2 blocking the access of activin to its type II receptor, which we show can bind Alk2 in the absence of ligand. These results show that the complement of other type I receptors in addition to the ligand-specific type I receptor can provide an important mechanism for modulating cell-specific responses to members of the TGFβ family.


2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Kelley E Anderson ◽  
Thomas A Bellio ◽  
Emily Aniskovich ◽  
Stephanie L Adams ◽  
Jan Krzysztof Blusztajn ◽  
...  

Abstract Cerebral amyloid angiopathy (CAA) in Alzheimer’s disease (AD)—deposition of beta amyloid (Aβ) within the walls of cerebral blood vessels—typically accompanies Aβ buildup in brain parenchyma and causes abnormalities in vessel structure and function. We recently demonstrated that the immunoreactivity of activin receptor-like kinase 1 (ALK1), the type I receptor for circulating BMP9/BMP10 (bone morphogenetic protein) signaling proteins, is reduced in advanced, but not early stages of AD in CA3 pyramidal neurons. Here we characterize vascular expression of ALK1 in the context of progressive AD pathology accompanied by amyloid angiopathy in postmortem hippocampi using immunohistochemical methods. Hippocampal arteriolar wall ALK1 signal intensity was 35% lower in AD patients (Braak and Braak Stages IV and V [BBIV-V]; clinical dementia rating [CDR1-2]) as compared with subjects with early AD pathologic changes but either cognitively intact or with minimal cognitive impairment (BBIII; CDR0-0.5). The intensity of Aβ signal in arteriolar walls was similar in all analyzed cases. These data suggest that, as demonstrated previously for specific neuronal populations, ALK1 expression in blood vessels is also vulnerable to the AD pathophysiologic process, perhaps related to CAA. However, cortical arterioles may remain responsive to the ALK1 ligands, such as BMP9 and BMP10 in early and moderate AD.


2016 ◽  
Vol 44 (4) ◽  
pp. 1142-1149 ◽  
Author(s):  
Amaya García de Vinuesa ◽  
Matteo Bocci ◽  
Kristian Pietras ◽  
Peter ten Dijke

Angiogenesis is a hallmark of cancer and is now a validated therapeutic target in the clinical setting. Despite the initial success, anti-angiogenic compounds impinging on the vascular endothelial growth factor (VEGF) pathway display limited survival benefits in patients and resistance often develops due to activation of alternative pathways. Thus, finding and validating new targets is highly warranted. Activin receptor-like kinase (ALK)1 is a transforming growth factor beta (TGF-β) type I receptor predominantly expressed in actively proliferating endothelial cells (ECs). ALK1 has been shown to play a pivotal role in regulating angiogenesis by binding to bone morphogenetic protein (BMP)9 and 10. Two main pharmacological inhibitors, an ALK1-Fc fusion protein (Dalantercept/ACE-041) and a fully human antibody against the extracellular domain of ALK1 (PF-03446962) are currently under clinical development. Herein, we briefly recapitulate the role of ALK1 in blood vessel formation and the current status of the preclinical and clinical studies on inhibition of ALK1 signalling as an anti-angiogenic strategy. Future directions in terms of new combination regimens will also be presented.


2005 ◽  
Vol 280 (23) ◽  
pp. 21858-21866 ◽  
Author(s):  
Nichole Boyer Arnold ◽  
Murray Korc

Smad7 is overexpressed in 50% of human pancreatic cancers. COLO-357 pancreatic cancer cells engineered to overexpress Smad7 are resistant to the actions of transforming growth factor-β1 (TGF-β1) with respect to growth inhibition and cisplatin-induced apoptosis but not with respect to modulation of gene expression. To delineate the mechanisms underlying these divergent consequences of Smad7 overexpression, we studied the effects of Smad7 on TGF-β1-dependent signaling pathways and cell cycle regulating proteins. TGF-β1 induced the phosphorylation of MAPK, p38 MAPK, and AKT2 irrespective of the levels of Smad7, and inhibitors of these pathways did not alter TGF-β1 actions on cell growth. By contrast, Smad7 overexpression interfered with TGF-β1-mediated attenuation of cyclin A and B levels, inhibition of cdc2 dephosphorylation and CDK2 inactivation, up-regulation of p27, and the maintenance of the retinoblastoma protein (RB) in a hypophosphorylated state. Smad7 also suppressed TGF-β1-mediated inhibition of E2F activity but did not alter TGF-β1-mediated phosphorylation of Smad2, the nuclear translocation of Smad2/3/4, or DNA binding of the Smad2/3/4 complex. Although Smad7 did not associate with the type I TGF-β receptor (TβRI), SB-431542, an inhibitor of the kinase activity of this receptor, blocked TGF-β1-mediated effects on Smad-2 phosphorylation. These findings point toward a novel paradigm whereby Smad7 acts to functionally inactivate RB and de-repress E2F without blocking the activation of TβRI and the nuclear translocation of Smad2/3, thereby allowing for TGF-β1 to exert effects in a cancer cell that is resistant to TGF-β1-mediated growth inhibition.


2012 ◽  
Vol 303 (1) ◽  
pp. E132-E143 ◽  
Author(s):  
Fang Zhao ◽  
Fengjie Huang ◽  
Mengxiong Tang ◽  
Xiaoming Li ◽  
Nina Zhang ◽  
...  

We demonstrated previously that the activation of ALK7 (activin receptor-like kinase-7), a member of the type I receptor serine/threonine kinases of the TGF-β superfamily, resulted in increased apoptosis and reduced proliferation through suppression of Akt signaling and the activation of Smad2-dependent signaling pathway in pancreatic β-cells. Here, we show that Nodal activates ALK7 signaling and regulates β-cell apoptosis. We detected Nodal expression in the clonal β-cell lines and rodent islet β-cells. Induction of β-cell apoptosis by treatment with high glucose, palmitate, or cytokines significantly increased Nodal expression in clonal INS-1 β-cells and isolated rat islets. The stimuli induced upregulation of Nodal expression levels were associated with elevation of ALK7 protein and enhanced phosphorylated Smad3 protein. Nodal treatment or overexpression of Nodal dose- or time-dependently increased active caspase-3 levels in INS-1 cells. Nodal-induced apoptosis was associated with decreased Akt phosphorylation and reduced expression level of X-linked inhibitor of apoptosis (XIAP). Remarkably, overexpression of XIAP or constitutively active Akt, or ablation of Smad2/3 activity partially blocked Nodal-induced apoptosis. Furthermore, siRNA-mediated ALK7 knockdown significantly attenuated Nodal-induced apoptosis of INS-1 cells. We suggest that Nodal-induced apoptosis in β-cells is mediated through ALK7 signaling involving the activation of Smad2/3-caspase-3 and the suppression of Akt and XIAP pathways and that Nodal may exert its biological effects on the modulation of β-cell survival and β-cell mass in an autocrine fashion.


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