Targeting Wnt-Frizzled signaling in cardiovascular diseases

XAV939 Inhibits Intima Formation by Decreasing Vascular Smooth Muscle Cell Proliferation and Migration Through Blocking Wnt Signaling

BACKGROUND

Excessive proliferation, migration, and oxidative stress of vascular smooth muscle cells (VSMCs) are key mechanisms involved in intima formation, which is the basic pathological process of in stent restenosis. This study aims at exploring the role of XAV939 in proliferation, migration, and reactive oxygen species (ROS) generation of VSMCs, and hence evaluating its effects on intima formation.

METHODS

Carotid artery ligation models for C57BL/6 mice were established and gave them different intervention: saline, XAV939, Axin2 overexpression adenovirus, and negative control adenovirus. The intima formation was assayed by intima area and intima/media ratio. To investigate the underlying mechanisms, primary rat VSMCs were cultured and treated with XAV939 and platelet-derived growth factor-BB. EdU, direct cell counting, cell wound-healing assay, and flow cytometry were used to measure proliferation, migration, cell cycle, apoptosis, and ROS generation of VSMCs, respectively. By Western blot, we examined proliferating cell nuclear antigen, Cyclin D1, Cyclin E, p21, β-actin, JNK, phosphorylated JNK, Axin2 and β-catenin expression. Immunofluorescence staining and confocal microscopy were conducted to detect translocation of β-catenin.

RESULTS

XAV939 inhibited intima formation, which was exhibited by the loss of intima area and I/M ratio and attenuated proliferation, migration, and ROS generation, as well as promoted cell cycle arrest of VSMCs. Specifically, XAV939 inhibited Wnt pathway.

CONCLUSIONS

XAV939 attenuates intima formation because of its inhibition of proliferation, migration, and apoptosis of VSMCs through suppression of Wnt signaling pathway.

Increment of HFABP Level in Coronary Artery In-Stent Restenosis Segments in Diabetic and Nondiabetic Minipigs: HFABP Overexpression Promotes Multiple Pathway-Related Inflammation, Growth and Migration in Human Vascular Smooth Muscle Cells

BACKGROUND

Our previous study suggested that heart-type fatty acid-binding protein (HFABP) levels were greatly elevated in the conditioned medium of explant culture of in-stent restenosis (ISR) tissue from diabetic minipigs compared with those of non-ISR tissue. We here verified this result in animal tissues and investigated the impact of HFABP overexpression in human aortic smooth muscle cells (hASMCs).

METHODS AND RESULTS

In Western blot and real-time RT-PCR, HFABP protein and mRNA levels were significantly higher in ISR than in non-ISR tissues from minipigs, and higher in the ISR tissue from diabetic minipigs than that from nondiabetic minipigs. The mRNA microarray and cellular effects of hASMC retroviral overexpression of HFABP and vector was analyzed. Compared with vector, HFABP transduction activates multiple signaling pathways (e.g. adipokine, TGF-β, Toll-like receptor, Wnt, Hedgehog, ErbB and Notch) and promotes inflammation, growth and migration in hASMCs whereas the knockdown of HFABP by small hairpin RNA attenuates these effects.

CONCLUSION

HFABP expression is significantly higher in ISR tissue than in non-ISR tissue from diabetic and nondiabetic minipigs. Overexpression of HFABP induces multiple pathway-related promotion of inflammation, growth and migration in vascular SMCs, suggesting a potential role in coronary artery ISR.

Hippocampal Wnt Signaling: Memory Regulation and Hormone Interactions

Wnt signaling has emerged in recent years as a major player in both nervous system development and adult synaptic plasticity. Of particular relevance to researchers studying learning and memory, Wnt signaling is critical for normal functioning of the hippocampus, a brain region that is essential for many types of memory formation and whose dysfunction is implicated in numerous neurodegenerative and psychiatric conditions. Impaired hippocampal Wnt signaling is implicated in several of these conditions, however, little is known about how Wnt signaling mediates hippocampal memory formation. This review will provide a general overview of Wnt signaling and discuss evidence demonstrating a key role for Wnt signaling in hippocampal memory formation in both normal and disease states. The regulation of Wnt signaling by ovarian sex steroid hormones will also be highlighted, given that the neuroprotection afforded by Wnt-hormone interactions may have significant implications for cognitive function in aging, neurodegenerative disease, and ischemic injury.

Stem cell guidance through the mechanistic target of rapamycin

Stem cells offer great promise for the treatment of multiple disorders throughout the body. Critical to this premise is the ability to govern stem cell pluripotency, proliferation, and differentiation. The mechanistic target of rapamycin (mTOR), 289-kDa serine/threonine protein kinase, that is a vital component of mTOR Complex 1 and mTOR Complex 2 represents a critical pathway for the oversight of stem cell maintenance. mTOR can control the programmed cell death pathways of autophagy and apoptosis that can yield variable outcomes in stem cell survival and be reliant upon proliferative pathways that include Wnt signaling, Wnt1 inducible signaling pathway protein 1 (WISP1), silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), and trophic factors. mTOR also is a necessary component for the early development and establishment of stem cells as well as having a significant impact in the regulation of the maturation of specific cell phenotypes. Yet, as a proliferative agent, mTOR can not only foster cancer stem cell development and tumorigenesis, but also mediate cell senescence under certain conditions to limit invasive cancer growth. mTOR offers an exciting target for the oversight of stem cell therapies but requires careful consideration of the diverse clinical outcomes that can be fueled by mTOR signaling pathways.

FoxO proteins in the nervous system

Acute as well as chronic disorders of the nervous system lead to significant morbidity and mortality for millions of individuals globally. Given the ability to govern stem cell proliferation and differentiated cell survival, mammalian forkhead transcription factors of the forkhead box class O (FoxO) are increasingly being identified as potential targets for disorders of the nervous system, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and auditory neuronal disease. FoxO proteins are present throughout the body, but they are selectively expressed in the nervous system and have diverse biological functions. The forkhead O class transcription factors interface with an array of signal transduction pathways that include protein kinase B (Akt), serum- and glucocorticoid-inducible protein kinase (SgK), IκB kinase (IKK), silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), growth factors, and Wnt signaling that can determine the activity and integrity of FoxO proteins. Ultimately, there exists a complex interplay between FoxO proteins and their signal transduction pathways that can significantly impact programmed cell death pathways of apoptosis and autophagy as well as the development of clinical strategies for the treatment of neurodegenerative disorders.

Wnt signaling cascade in restenosis: a potential therapeutic target of public health relevance in a North American cohort of Nebraska State

Cardiovascular disease is a leading cause of morbidity and mortality in United States, including Nebraska. Neointimal hyperplasia leading to restenosis is a major public health problem. Identification of key signaling molecules in biochemical pathways is an attractive strategy for development of predictive biomarkers in occlusive vascular diseases (OVD). Our pilot study aimed to identify the role of Wnt-frizzled signaling in restenosis in a North American cohort. North American patients (n = 9) undergoing coronary artery bypass graft surgery at Nebraska Heart Institute, Lincoln, were enrolled. Human saphenous veins (SV) (n = 9) and left internal mammary arteries (LIMA) (n = 9) received post-surgery at Creighton University, Omaha, were harvested using Collagenase-IV digestion method. Isolated primary VSMCs were cultured for 3-4 weeks, and passages P3-P7, were used for molecular biology experiments. The study was approved by the Institutional Review Board. RNA was extracted using trizol method and mRNA transcripts were identified using reverse transcriptase-polymerase chain reaction followed by 2% agarose gel electrophoresis. Mean age of surgery patients (n = 9) was 60.3 years (SD ± 6.5 years). Wnt2 and Wnt5a mRNA transcripts were expressed in human VSMCs; however, Wnt1, Wnt4 and Wnt11 mRNA were not expressed; beta-actin was used as an internal control. Receptor studies demonstrated the expression of Fzd1, Fzd2 and Fzd5 mRNA in hVSMCs. Our preliminary data implicates the public health significance of Wnt signaling in bypass graft patients in Nebraska. Future molecular biology approach-based community health studies targeting Wnt pathway may aid in the development of cost-effective predictive biomarkers for OVD susceptible populations.