Inhibition of farnesyl pyrophosphate synthase attenuates angiotensin II-induced fibrotic responses in vascular smooth muscle cells

Modulation of the RAC1/MAPK/ERK signalling pathway by farnesyl diphosphate synthase regulates granulosa cells proliferation in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex gynaecological endocrine disease that occurs in women of childbearing age. The pathogenesis of PCOS is still unclear and further exploration is needed. Here, proteomic analysis indicated that the expression of farnesyl diphosphate synthase (FDPS) protein in ovarian tissue of PCOS mice was significantly decreased. The purpose of this study is to investigate the relationship between potential biomarkers of PCOS and granulosa cells (GCs) function. The mechanisms by which FDPS affected the proliferation of granulosa cells were also explored both in vitro and in vivo. We found that knockdown of FDPS inhibited the proliferation of KGN (human ovarian granulosa cell line), while overexpression of FDPS had the opposite effect. FDPS activated Rac1 (Rac Family Small GTPase 1) activity and regulated MAPK/ERK signalling pathway, which affecting the proliferation of KGN cells significantly. In addition, treatment with the adeno-associated virus (AAV)-FDPS reverses the dehydroepiandrosterone (DHEA)-induced PCOS-phenotype in mice. Our data indicated that FDPS could regulate the proliferation of ovarian GCs by modulating MAPK/ERK (mitogen-activated protein kinase/extracellular regulated protein kinases) pathway via activating Rac1 activity. These findings suggest that FDPS could be of great value for the regulation of ovarian granulosa cell function and the treatment of PCOS.

The role of angiotensin II activation of yes-associated protein/PDZ-binding motif signaling in hypertensive cardiac and vascular remodeling

Vascular remodeling is the pathogenic basis of hypertension and end organ injury, and the proliferation of vascular smooth muscle cells (VSMCs) is central to vascular remodeling. Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are key effectors of the Hippo pathway and crucial for controlling cell proliferation, apoptosis and differentiation. The present study investigated the role of YAP/TAZ in cardiac and vascular remodeling of angiotensin II-induced hypertension. Ang II induced YAP/TAZ activation in the heart and aorta, which was prevented by YAP/TAZ inhibitor verteporfin. Treatment with verteporfin significantly reduced Ang II-induced cardiac and vascular hypertrophy with a mild reduction in systolic blood pressure (SBP), verteporfin attenuated Ang II-induced cardiac and aortic fibrosis with the inhibition of transform growth factor (TGF)β/Smad2/3 fibrotic signaling and extracellular matrix collagen I deposition. Ang II induced Rho A, extracellular signal-regulated kinase 1/2 (ERK1/2) and YAP/TAZ activation in VSMCs, either Rho kinase inhibitor fasudil or ERK inhibitor PD98059 suppressed Ang II-induced YAP/TAZ activation, cell proliferation and fibrosis of VSMCs. Verteporfin also inhibited Ang II-induced VSMC proliferation and fibrotic TGFβ1/Smad2/3 pathway. These results demonstrate that Ang II activates YAP/TAZ via Rho kinase/ERK1/2 pathway in VSMCs, which may contribute to cardiac and vascular remodeling in hypertension. Our results suggest that YAP/TAZ plays a critical role in the pathogenesis of hypertension and end organ damage, and targeting the YAP/TAZ pathway may be a new strategy for the prevention and treatment of hypertension and cardiovascular diseases.

Key Enzymes for the Mevalonate Pathway in the Cardiovascular System

ABSTRACT

Isoprenylation is an important post-transcriptional modification of small GTPases required for their activation and function. Isoprenoids, including farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate, are indispensable for isoprenylation by serving as donors of a prenyl moiety to small G proteins. In the human body, isoprenoids are mainly generated by the mevalonate pathway (also known as the cholesterol-synthesis pathway). The hydroxymethylglutaryl coenzyme A reductase catalyzes the first rate-limiting steps of the mevalonate pathway, and its inhibitor (statins) are widely used as lipid-lowering agents. In addition, the FPP synthase is also of critical importance for the regulation of the isoprenoids production, for which the inhibitor is mainly used in the treatment of osteoporosis. Synthetic FPP can be further used to generate geranylgeranyl pyrophosphate and cholesterol. Recent studies suggest a role for isoprenoids in the genesis and development of cardiovascular disorders, such as pathological cardiac hypertrophy, fibrosis, endothelial dysfunction, and fibrotic responses of smooth-muscle cells. Furthermore, statins and FPP synthase inhibitors have also been applied for the management of heart failure and other cardiovascular diseases rather than their clinical use for hyperlipidemia or bone diseases. In this review, we focus on the function of several critical enzymes, including hydroxymethylglutaryl coenzyme A reductase, FPP synthase, farnesyltransferase, and geranylgeranyltransferase in the mevalonate pathway which are involved in regulating the generation of isoprenoids and isoprenylation of small GTPases, and their pathophysiological role in the cardiovascular system. Moreover, we summarize recent research into applications of statins and the FPP synthase inhibitors to treat cardiovascular diseases, rather than for their traditional indications respectively.

Farnesyl Pyrophosphate Synthase Blocker Ibandronate Reduces Thoracic Aortic Fibrosis in Diabetic Rats

BACKGROUND

This study assessed the effect of ibandronate (IBN), a farnesyl pyrophosphate synthase (FPPS) inhibitor, on vascular remodeling in diabetic rats.

METHODS

A rat model of diabetes was induced by a high-fat and high-sugar diet combined with a small dose of streptozotocin. The diabetic rats received 5 µg/kg of ibandronate solution or normal saline subcutaneously every morning for 16 weeks. The morphology of the thoracic aorta was assessed by hematoxylin and eosin and Masson's trichrome staining techniques. Gene expression levels of connective tissue growth factor (CTGF) and FPPS were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) analysis. CTGF and FPPS protein levels were determined by Western blotting analysis.

RESULTS

Rats with diabetes mellitus showed moderate hyperglycemia, insulin resistance, hyperlipidemia and thoracic aortic fibrosis. FPPS was significantly upregulated in the thoracic aorta from diabetic animals. Interestingly, IBN treatment for 16 weeks alleviated the diabetes-induced histopathologic changes in the thoracic aortic wall and reduced CTGF protein and mRNA levels.

CONCLUSIONS

These findings provided evidence that FPPS is involved in thoracic aortic fibrosis in diabetic rats. Meanwhile, IBN could alleviate vascular remodeling in diabetic animals.

FPPS mediates TGF-β1-induced non-small cell lung cancer cell invasion and the EMT process via the RhoA/Rock1 pathway

Farnesyl pyrophosphate synthase (FPPS), a key enzyme in the mevalonate pathway, was recently shown to play a role in cancer progression. However, its role in non-small cell lung cancer (NSCLC) metastasis and the underlying mechanism remain unclear. In this study, FPPS expression was significantly correlated with TNM stage, and metastasis. Inhibition or knockdown of FPPS blocked TGF-β1-induced cell invasion and epithelial-to-mesenchymal transition (EMT) process. FPPS expression of FPPS was induced by TGF-β1 and FPPS promoted cell invasion and EMT via the RhoA/Rock1 pathway. In conclusion, FPPS mediates TGF-β1-induced lung cancer cell invasion and EMT via the RhoA/Rock1 pathway. These findings suggest new treatment strategies to reduce mortality associated with metastasis in patients with NSCLC.

LncRNA BANCR facilitates vascular smooth muscle cell proliferation and migration through JNK pathway

Deregulated migration and proliferation of vascular smooth muscle cells (VSMCs) acts a crucial role in the pathogenesis of many cardiovascular diseases such as atherosclerosis, coronary heart disease and hypertension. Long noncoding RNAs (lncRNAs) play crucial functional roles in a lot of biological processes such as cell development, cell proliferation, differentiation and invasion. In our study, we demonstrated that the BANCR expression level was upregulated in the atherosclerotic plaques tissues compared to in the normal vessels tissues. TNF-α could emhance the VSMCs proliferation. The expression level of BANCR and p-JNK were upregulated and activated in the proliferating VSMCs. Overexpression of BANCR enhanced VSMCs proliferation and migration. Elevated expression of BANCR induced JNK activation, which can be decreased by the specific JNK inhibitor SP600125. We demonstrated that ectopic expression of BANCR increased the VSMCs proliferation and migration through activating JNK pathway. These data suggested that lncRNA BANCR acts a crucial role in the regulating VSMCs proliferation and migration partly by activating the JNK pathway.

Gene expression profiles and signaling mechanisms in α2B-adrenoceptor-evoked proliferation of vascular smooth muscle cells

BACKGROUND

α2-adrenoceptors are important regulators of vascular tone and blood pressure. Regulation of cell proliferation is a less well investigated consequence of α2-adrenoceptor activation. We have previously shown that α2B-adrenoceptor activation stimulates proliferation of vascular smooth muscle cells (VSMCs). This may be important for blood vessel development and plasticity and for the pathology and therapeutics of cardiovascular disorders. The underlying cellular mechanisms have remained mostly unknown. This study explored pathways of regulation of gene expression and intracellular signaling related to α2B-adrenoceptor-evoked VSMC proliferation.

RESULTS

The cellular mechanisms and signaling pathways of α2B-adrenoceptor-evoked proliferation of VSMCs are complex and include redundancy. Functional enrichment analysis and pathway analysis identified differentially expressed genes associated with α2B-adrenoceptor-regulated VSMC proliferation. They included the upregulated genes Egr1, F3, Ptgs2 and Serpine1 and the downregulated genes Cx3cl1, Cav1, Rhoa, Nppb and Prrx1. The most highly upregulated gene, Lypd8, represents a novel finding in the VSMC context. Inhibitor library screening and kinase activity profiling were applied to identify kinases in the involved signaling pathways. Putative upstream kinases identified by two different screens included PKC, Raf-1, Src, the MAP kinases p38 and JNK and the receptor tyrosine kinases EGFR and HGF/HGFR. As a novel finding, the Src family kinase Lyn was also identified as a putative upstream kinase.

CONCLUSIONS

α2B-adrenoceptors may mediate their pro-proliferative effects in VSMCs by promoting the activity of bFGF and PDGF and the growth factor receptors EGFR, HGFR and VEGFR-1/2. The Src family kinase Lyn was also identified as a putative upstream kinase. Lyn is known to be expressed in VSMCs and has been identified as an important regulator of GPCR trafficking and GPCR effects on cell proliferation. Identified Ser/Thr kinases included several PKC isoforms and the β-adrenoceptor kinases 1 and 2. Cross-talk between the signaling mechanisms involved in α2B-adrenoceptor-evoked VSMC proliferation thus appears to involve PKC activation, subsequent changes in gene expression, transactivation of EGFR, and modulation of kinase activities and growth factor-mediated signaling. While many of the identified individual signals were relatively small in terms of effect size, many of them were validated by combining pathway analysis and our integrated screening approach.

Chemical approaches to inhibitors of isoprenoid biosynthesis: targeting farnesyl and geranylgeranyl pyrophosphate synthases

The chemical synthesis of farnesyl and geranylgeranyl pyrophosphate synthase inhibitors are surveyed.