Expression Of Activin Receptor-like Kinase Research Articles

Effects of Benzo(a)pyrene on the endometrial receptivity and embryo implantation in mice: An experimental study.

BackgroundBenzo(a)pyrene (BaP) as an environmental pollutant is ubiquitous in the environment and it has destructive effects on human health. So far, various studies have demonstrated that BaP can cause adverse effects on the female reproductive system, but the existing information is limited about the effects of BaP on the endometrial receptivity and embryo implantation. ObjectiveThe aim of this study was to investigate the effects of BaP on the endometrial receptivity and implantation in mice.Materials and MethodsIn this experimental study, 40 pregnant BALB/c mice were divided into 5 groups (n = 8/each) as follows: experimental groups received the doses of 100 µg/kg, 200 µg/kg, and 500 µg/kg BaP dissolved in corn oil, the control group received normal saline and sham group received corn oil. Pregnant mice administered these solutions from Day 1 to Day 5 of gestation by gavage. On Day 6, the mice were sacrificed. Then their embryos were counted and the hormonal, histomorphological and molecular analyses were performed on the mocusa of uterine tube.ResultsThe data revealed that BaP reduces estrogen and progesterone levels, decreases the number of implantation site, endometrium thickness, uterine lumen diameter, stromal cells and endometrial glands, and blood vessels in the endometrium. However, the expression of Activin receptor-like kinase 5 and E-cadherin genes was not changed by BaP with different doses.ConclusionThe finding of this study showed that BaP can change estrogen and progesterone levels, and endometrial morphology leads to impairing the endometrial receptivity and decreasing the number of implantation site.

MiR-338-3p inhibits the invasion of renal cell carcinoma by downregulation of ALK5.

BackgroundThe current study aims to elucidate the role of miRNA-338-3p (miR-338-3p) in the invasion of renal cell carcinoma (RCC).MethodsQuantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-338-3p in human RCC cell lines with high metastatic potential (Caki-1) and low metastatic potential (786-O), respectively. The Caki-1 and 786-O cells were transfected with miR-338-3p mimic or inhibitor. Wound healing assay, Transwell assay and western blotting were performed to analyze the invasive ability and expression of activin receptor-like kinase 5 (ALK5) in the RCC cell lines. During the 36-month follow-up, we detected the expressions of miR-338-3p and ALK5 in 22 RCC cases with metastasis and 60 cases achieving a remission.ResultsmiR-339-3p was significantly downregulated in the Caki-1 cells as compared with the 786-O cells. The transfection with miR-338-3p inhibitor caused an increased invasive ability of both two cell lines. However, the transfection with miR-338-3p mimic caused a reduction of the invasiveness. In RCC cells, the expression of ALK5 was negatively correlated to miR-338-3p. Upregulation of ALK5 partially counteracted the miR-338-3p-induced invasiveness of RCC cells. We subsequently found the negative correlations between miR-338-3p and metastasis/ALK5 expression could be also observed in human RCC tissues.ConclusionTaken together, these results indicate that miR-338-3p acts as a novel tumor suppressor to inhibit the invasion of RCC by regulating ALK5 expression.

ALK1 expression in oral lichen planus: a possible relation to microvessel density.

To assess the expression of activin receptor-like kinase 1 (ALK1) and investigate its possible relationship with microvessel density (MVD) in different forms of oral lichen planus (OLP) compared to controls' biopsies. Biopsies from 20 reticular/papular OLP (R/PLP), 20 atrophic/erosive OLP (A/ELP) patients, and 20 healthy subjects were immunohistochemically analyzed and statistically compared and correlated for ALK1 expression and MVD as assessed by CD34 expression. All OLP specimens revealed the presence of positive cytoplasmic CD34 immunostaining in endothelial cells, with statistically high significant MVD in each of R/PLP (Median; M = 4.40) and A/ELP (M = 7.69) compared to controls (M = 1.16) (P < 0.001). Statistically significant MVD was found in A/ELP compared to R/PLP (P < 0.001). All control specimens revealed negative ALK1 immunostaining of the few inflammatory cells found, while 85% of A/ELP cases and 70% of R/PLP cases showed positively immunostained sections for ALK-1, with statistically significant higher ALK1 expression In A/ELP (M = 1.95) compared to R/PLP (M = 0.86) (P = 0.005). No significant correlation between CD34 and ALK1 was detected in R/PLP (r = 0.081), while a barely moderate positive correlation was found in A/ELP (r = 0.396). ALK1 expression and MVD are increased in OLP, particularly in A/ELP type.

Circulating Bmp10 acts through endothelial Alk1 to mediate flow-dependent arterial quiescence

Blood flow plays crucial roles in vascular development, remodeling and homeostasis, but the molecular pathways required for transducing flow signals are not well understood. In zebrafish embryos, arterial expression of activin receptor-like kinase 1 (alk1), which encodes a TGFβ family type I receptor, is dependent on blood flow, and loss of alk1 mimics lack of blood flow in terms of dysregulation of a subset of flow-responsive arterial genes and increased arterial endothelial cell number. These data suggest that blood flow activates Alk1 signaling to promote a flow-responsive gene expression program that limits nascent arterial caliber. Here, we demonstrate that restoration of endothelial alk1 expression to flow-deprived arteries fails to rescue Alk1 activity or normalize arterial endothelial cell gene expression or number, implying that blood flow may play an additional role in Alk1 signaling independent of alk1 induction. To this end, we define cardiac-derived Bmp10 as the crucial ligand for endothelial Alk1 in embryonic vascular development, and provide evidence that circulating Bmp10 acts through endothelial Alk1 to limit endothelial cell number in and thereby stabilize the caliber of nascent arteries. Thus, blood flow promotes Alk1 activity by concomitantly inducing alk1 expression and distributing Bmp10, thereby reinforcing this signaling pathway, which functions to limit arterial caliber at the onset of flow. Because mutations in ALK1 cause arteriovenous malformations (AVMs), our findings suggest that an impaired flow response initiates AVM development.

Inhibition of TGF-β1-receptor posttranslational core fucosylation attenuates rat renal interstitial fibrosis

The profibrotic cytokine transforming growth factor-β1 (TGF-β1) causes renal fibrosis by binding to receptors at the cell surface; however, it is not clear which of the TGF-β superfamily receptors correlates with renal fibrosis. To resolve this, we quantified TGF-β superfamily receptor expression in the kidneys of rats with unilateral ureteral obstruction using a real-time PCR gene array. Expression of activin receptor-like kinase (ALK)-5, ALK7, and TGF-β receptor II (TGF-βRII) mRNA increased significantly, while ALK6 mRNA expression was significantly decreased in the obstructed rat kidney. Core fucosylation is essential for the proper function of both TGF-βRII and ALK5 in cultured human renal proximal tubular epithelial cells in vitro. Therefore, we targeted posttranslational core fucosylation, regulated by α-1,6 fucosyltransferase (FUT8), by adenoviral-mediated knockdown of FUT8 mRNA in vivo and measured TGF-βRII and ALK5 expression and the progression of renal fibrosis. Despite long-term obstruction injury, inhibition of TGF-βRII and ALK5 of core fucosylation ameliorated the progression of renal fibrosis, an effect independent of TGF-βRII and ALK5 expression. Thus, the regulation of TGF-β1-receptor core fucosylation may provide a novel potential therapeutic strategy for treating renal fibrosis.

Reduced expression of activin receptor-like kinase 7 in breast cancer is associated with tumor progression

To explore the clinical implication of activin receptor-like kinase 7 (ALK7) expression in breast cancer, we evaluated its protein level in six kinds of human breast tissue samples, including adjacent normal tissues, adenosis, breast fibroadenoma, ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and lymph node metastases (LNM). Immunohistochemical analyses showed that ALK7 was more frequently and much more intensely expressed in adjacent normal tissues, adenosis, and fibroadenoma tissues than in malignant tissues (DCIS, IDC, and LNM). Furthermore, the ALK7 expression in primary tumors and the corresponding LNM was evaluated in parallel samples from 60 patients with IDC. Results showed that the ALK7 expression status in primary tumors and LNM was concordant in 53 patients (88%), suggesting that ALK7 expression was retained in LNM. Moreover, our results suggested that ALK7 expression inversely correlated with the tumor grade (P=0.009) and clinical stage (P=0.004) in IDC significantly. Finally, the effect of activin-ALK7 pathway on the breast cancer cell growth was elucidated, and results revealed that overexpression of ALK7 could restore the inhibitory effect of activin B on the growth of ALK7-negative breast cancer cell line, ZR-75-30. These findings provide the evidence that the reduction or lack of ALK7 expression may account for the loss of its ligand sensitivity of breast cancer cells, thereby leading to breast tumor progression.

An enhancer region of the ALK1 gene resides in its intron 2

Expression of activin receptor‐like kinase 1 (ALK1) gene is undetectable in most of the organs in adults; however, it is specifically induced in arteries feeding ischemic lesions. This gene, with its unique expression pattern, might be exploited to aid in the delivery of a therapeutic peptide to downstream ischemic tissues. Previously, we generated a shortened 4.8 kb Alk1PIB (Promoter‐Intron 2B) regulatory fragment that recapitulates the endogenous mouse ALK1 regulatory activity. In order to elucidate the regulatory mechanisms further, we utilized evolutionarily conserved region (ECR) analysis to identify highly conserved regulatory regions in this study. An alignment of ALK1 gene sequences revealed a 152 bp sequence conserved among 11 mammals within the intron 2B region. To test the regulatory function of this 152‐bp coreECR sequence, recombinant adenoviruses expressing fluorescent reporter were created. Compared to an Alk1PIB virus, the coreECR‐deleted Alk1PIB(d1) virus showed significantly reduced reporter gene expression in cultured arterial endothelial cells, indicating an enhancer function of this sequence. This approach should help us further engineer the ALK1 regulatory region to create short and strong fragment that may be utilized in future gene therapy of various disorders including malignant tumors and ischemic heart diseases. This work was supported by the American Heart Association.

ALK7 expression is specific for adipose tissue, reduced in obesity and correlates to factors implicated in metabolic disease

Human adipose tissue is a major site of expression of inhibin beta B (INHBB) which homodimerizes to form the novel adipokine activin B. Our aim was to determine if molecules needed for a local action of activin B are expressed in adipose tissue.Microarray analysis showed that adipose tissue expressed activin type I and II receptors and that the expression of activin receptor-like kinase 7 (ALK7) was adipose tissue specific. In obesity discordant siblings from the SOS Sib Pair study, adipose tissue ALK7 expression was higher in lean (n=90) compared to obese (n=90) subjects (p=4×10−31). Adipose tissue ALK7 expression correlated with several measures of body fat, carbohydrate metabolism and lipids. In addition, ALK7 and INHBB expression correlated but only in lean subjects and in subjects with normal glucose tolerance.We conclude that activin B may have local effects in adipose tissue and thereby influence obesity and its comorbidities.

Sonic hedgehog signaling promotes motility and invasiveness of gastric cancer cells through TGF- -mediated activation of the ALK5-Smad 3 pathway

It is known that the activation of hedgehog (Hh) signaling is involved in the progression and invasion of various tumors, including gastric carcinoma. In this study, we investigated the impact of transforming growth factor (TGF)-beta signaling on the sonic hedgehog (Shh)-mediated invasion of gastric cancer cells. We found that higher concentrations of N-Shh enhanced cell motility and invasiveness in gastric cancer cells, whereas no increase was observed in cells that were treated with KAAD-cyclopamine (a Shh signaling inhibitor) or anti-Shh blocking antibodies. In addition, the N-Shh-induced migration and invasiveness of gastric cancer cells were reduced by treatment with anti-TGF-beta blocking antibody or TGF-beta1 small interfering RNA (siRNA) in presence of N-Shh when compared with control groups. Furthermore, TGF-beta1 secretion, TGF-beta-mediated transcriptional response, expression of activin receptor-like kinase (ALK) 5 protein and phosphorylation of Smad 3 were also enhanced by treatment with N-Shh, but not KAAD-cyclopamine, anti-Shh or TGF-beta1 blocking antibodies. Blockade of the ALK5 kinase in the presence of N-Shh significantly inhibited phosphorylation of Smad 3, activity of matrix metalloproteinases and Shh-induced cell motility/invasiveness. Importantly, transient expression of ALK5 siRNA or Smad 3 siRNA reduced the ability of N-Shh to stimulate migration and invasion of those cells compared with the cells treated with non-specific control siRNA. In summary, these results indicate that Shh promotes motility and invasiveness of gastric cancer cells through TGF-beta-mediated activation of the ALK5-Smad 3 pathway. Additionally, our findings are the first to suggest a role and mechanism for Shh signaling as it relates to the metastatic potential of gastric cancer, thereby indicating potential therapeutic molecular targets to decrease metastasis.

Antitumor activity of ALK1 in pancreatic carcinoma cells

In this study, the authors investigated the expression of activin receptor-like kinase 1 (ALK1) in pancreatic carcinoma and evaluated its potential role as a tumor suppressor in vitro and in vivo. Endogenous ALK1 expression was demonstrated by immunohistochemistry in both pancreatic tumor tissue and peritumoral normal tissue from 6 patients and by RT-PCR in 8/12 established pancreatic cancer cell lines. Ectopic expression of a constitutively active (ca) ALK1 mutant in TGF-beta sensitive PANC-1 and COLO-357 cells augmented transcriptional activation of a Smad2/3 responsive reporter, and slowed down basal growth in vitro. Both effects were further enhanced by TGF-beta/ALK5 stimulation, suggesting largely independent nuclear Smad signaling by both type I receptors. Upon orthotopic transplantation of PANC-1-caALK1 into immunodeficient mice, tumor size was strongly reduced and was associated with a lower microvessel density in the PANC-1-caALK1-derived tumors. In vitro, this mutant efficiently blocked TGF-beta-induced epithelial-to-mesenchymal transdifferentiation and suppressed TGF-beta/ALK5-mediated activation of the p38 MAPK pathway. Mechanistically, caALK1 silenced MyD118, an immediate TGF-beta target gene whose protein product, GADD45beta, couples Smad signaling to p38 activation. These results show that ALK1 activation in pancreatic tumor cells is antioncogenic by inducing ALK5-independent growth inhibition and by blocking TGF-beta/ALK5-mediated epithelial-to-mesenchymal transdifferentiation and, possibly, invasion and metastatic progression.