Identification of a novel MTOR activator and discovery of a competing endogenous RNA regulating autophagy in vascular endothelial cells

A current pharmacologic agent versus the promise of next generation therapeutics to ameliorate protein misfolding and/or aggregation diseases

The list of protein aggregation-associated degenerative diseases is long and growing, while the portfolio of disease-modifying strategies is very small. In this review and perspective, we assess what has worked to slow the progression of an aggregation-associated degenerative disease, covering the underlying mechanism of pharmacologic action and what we have learned about the etiology of the transthyretin amyloid diseases and likely amyloidoses in general. Next, we introduce emerging therapies that should apply more generally to protein misfolding and/or aggregation diseases, approaches that rely on adapting the protein homeostasis or proteostasis network for disease amelioration.

A synthesized butyrolactone derivative in combination with chloroquine can inhibit cancer cell growth and lysosome vacuolation induced by chloroquine in A549 lung cancer cells

3BDO in combination with chloroquine could elevate the Na⁺,K⁺-ATPase activity and decrease the expression of competing endogenous non-coding RNA TGFB2-OT1. Therefore, ​ the combination inhibited the cells growth and lysosomal vacuolation induced by CQ.

Potential roles of annexin A7 GTPase in autophagy, senescence and apoptosis

This review covers the roles of ANXA7 GTPase in orchestrating autophagy, senescence and apoptosis interactive networks in various cell types.

Microarray expression profiling and gene ontology analysis of long non-coding RNAs in spontaneously hypertensive rats and their potential roles in the pathogenesis of hypertension

Long non-coding RNAs (lncRNAs) have been demonstrated to be significant in numerous biological processes. Hypertension is a form of cardiovascular disease with at least one billion cases worldwide. The present study sought to compare the differential expression profiles of lncRNAs in the renal cortex of spontaneously hypertensive rats (SHRs) and normotensive Wistar‑Kyoto (WKY) rats. The ipsilateral renal cortex was obtained from 15‑week‑old SHRs and WKY rats whose blood pressures had been monitored. Total RNA was extracted using TRIzol, and lncRNAs and messenger RNAs were profiled by microarray and validated using fluorescent quantitative reverse transcription‑polymerase chain reaction. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the function of differentially expressed genes. Microarray analysis demonstrated that 145 lncRNAs were differentially expressed between SHRs and WKY rats. GO and KEGG pathway analysis indicated that these lncRNAs are involved in numerous biological processes. Thus, lncRNAs may contribute to the pathogenesis of hypertension.

Integrative proteomic and microRNA analysis of the priming phase during rat liver regeneration

The partial hepatectomy (PH) model provides an effective medium for study of liver regeneration (LR). Considering that LR is regulated by microRNAs (miRNAs), investigation of the regulatory role of miRNAs is critical for revealing how regenerative processes are initiated and controlled. Using high-throughput sequencing technology, we examined miRNA expression profiles of the regenerating rat liver after PH, and found that 23 miRNAs were related to rat LR. Among them, several miRNAs were significantly altered at 2h and 6h after PH, corresponding to the priming phase of LR. Furthermore, we examined the protein profiles in the regenerating rat liver at 2h and 6h after PH by iTRAQ coupled with LC-MS/MS, and found that 278 proteins were significantly changed. Subsequently, an integrative proteomic and microRNA analysis by Ingenuity Pathway Analysis 9.0 (IPA) software showed that miR-125a, miR-143, miR-150, miR-181c, miR-182, miR-183, miR-199a, miR-429 regulated the priming phase of rat LR by modulating the expression of proteins involved in networks critical for cell apoptosis, cell survival, cell cycle, inflammatory response, metabolism, etc. Thus, our studies provide novel evidence for a functional molecular network populated by the down-regulated targets of the up-regulated miRNAs in the priming phase of rat LR.

Long noncoding RNA FER1L4 suppresses cancer cell growth by acting as a competing endogenous RNA and regulating PTEN expression

Aberrantly expressed long noncoding RNAs (lncRNAs) are associated with various cancers. However, the roles of lncRNAs in the pathogenesis of most cancers are unclear. Here, we report that the lncRNA FER1L4 (fer-1-like family member 4, pseudogene) acts as a competing endogenous RNA (ceRNA) to regulate the expression of PTEN (a well-known tumor suppressor gene) by taking up miR-106a-5p in gastric cancer. We observed that FER1L4 was downregulated in gastric cancer and that its level corresponded with that of PTEN mRNA. Both FER1L4 and PTEN mRNA were targets of miR-106a-5p. Further experiments demonstrated that FER1L4 downregulation liberates miR-106a-5p and decreases the abundances of PTEN mRNA and protein. More importantly, FER1L4 downregulation accelerated cell proliferation by promoting the G₀/G₁ to S phase transition. We conclude that one mechanism by which lncRNAs function in in tumorigenesis is as ceRNAs for tumor suppressor mRNAs.

The short and long of noncoding sequences in the control of vascular cell phenotypes

The two principal cell types of importance for normal vessel wall physiology are smooth muscle cells and endothelial cells. Much progress has been made over the past 20 years in the discovery and function of transcription factors that coordinate proper differentiation of these cells and the maintenance of vascular homeostasis. More recently, the converging fields of bioinformatics, genomics, and next generation sequencing have accelerated discoveries in a number of classes of noncoding sequences, including transcription factor binding sites (TFBS), microRNA genes, and long noncoding RNA genes, each of which mediates vascular cell differentiation through a variety of mechanisms. Alterations in the nucleotide sequence of key TFBS or deviations in transcription of noncoding RNA genes likely have adverse effects on normal vascular cell phenotype and function. Here, the subject of noncoding sequences that influence smooth muscle cell or endothelial cell phenotype will be summarized as will future directions to further advance our understanding of the increasingly complex molecular circuitry governing normal vascular cell differentiation and how such information might be harnessed to combat vascular diseases.

Long noncoding RNAs in cardiovascular diseases

In recent year, increasing evidence suggests that noncoding RNAs play important roles in the regulation of tissue homeostasis and pathophysiological conditions. Besides small noncoding RNAs (eg, microRNAs), >200-nucleotide long transcripts, namely long noncoding RNAs (lncRNAs), can interfere with gene expressions and signaling pathways at various stages. In the cardiovascular system, studies have detected and characterized the expression of lncRNAs under normal physiological condition and in disease states. Several lncRNAs are regulated during acute myocardial infarction (eg, Novlnc6) and heart failure (eg, Mhrt), whereas others control hypertrophy, mitochondrial function and apoptosis of cardiomyocytes. In the vascular system, the endothelial-expressed lncRNAs (eg, MALAT1 and Tie-1-AS) can regulate vessel growth and function, whereas the smooth-muscle-expressed lncRNA smooth muscle and endothelial cell-enriched migration/differentiation-associated long noncoding RNA was recently shown to control the contractile phenotype of smooth muscle cells. This review article summarizes the data on lncRNA expressions in mouse and human and highlights identified cardiovascular lncRNAs that might play a role in cardiovascular diseases. Although our understanding of lncRNAs is still in its infancy, these examples may provide helpful insights how lncRNAs interfere with cardiovascular diseases.

Heterogeneous nuclear ribonucleoprotein E1 regulates protein disulphide isomerase translation in oxidized low-density lipoprotein-activated endothelial cells

AIMS

Endothelium-derived protein disulphide isomerase (PDI) is required for thrombus formation in vivo. But, how to control PDI overproduction in oxidized low-density lipoprotein (oxLDL)-activated vascular endothelial cells (VECs) is not well understood. In this study, we try to answer this question using our newly identified activator of mTOC1 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2 (3H)-one (3BDO) that has been shown to protect VECs.

METHODS

First, we performed a proteomics analysis on the oxLDL-activated vascular VECs in the presence or absence of 3BDO. Next, we constructed the heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1) mutants at Ser43 and used the RNA-ChIP technique to investigate the relationship between hnRNP E1 and PDI production. Furthermore, we examined the effect of 3BDO on oxLDL-altered phosphorylation of Akt1 and Akt2. Finally, we studied the effect of 3BDO on oxLDL-altered PDI protein level in apolipoprotein E(-/-) mice with advanced atherosclerosis.

RESULTS

In VECs, oxLDL-increased PDI protein level, induced hnRNP E1 phosphorylation at Ser43, suppressed the binding of hnRNP E1 to PDI 5'UTR and induced the phosphorylation of Akt2 but not Akt1. All of these processes were blocked by 3BDO. Importantly, Ser43 mutant of hnRNP E1 inhibited the increase of PDI protein level and the decrease of the binding of hnRNP E1 and PDI 5'UTR induced by oxLDL. Furthermore, 3BDO suppressed oxLDL-induced PDI protein increase in the serum and plaque endothelium of apolipoprotein E(-/-) mice.

CONCLUSION

hnRNP E1 is a new regulator of PDI translation in oxLDL-activated VECs, and 3BDO is a powerful agent for controlling PDI overproduction.

A 3'UTR-associated RNA, FLJ11812 maintains stemness of human embryonic stem cells by targeting miR-4459

The 3' untranslated region (UTR)-associated RNAs (uaRNAs) have important roles in various biological processes, especially in development. However, since they overlap with protein-coding mRNAs, uaRNAs are difficult to study by RNA interference techniques. We recently identified a chemical molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO), that could efficiently induce human embryonic stem cells (hESCs) differentiation, and meanwhile selectively and efficiently downregulate the uaRNA FLJ11812. By acting as a competing endogenous RNA, downregulated FLJ11812 by 3BDO further increased miR-4459 level in hESCs. miR-4459 could decrease the expression of its targets, CDC20B and ATG13, and thus altered stemness via cell cycle and autophagy. Our results revealed that FLJ11812 played a key role in maintenance of stemness of hESCs for the first time. The findings provide new clues and a powerful tool for investigating the action mechanism of FLJ11812 in early development.

Noncoding RNAs regulate NF-κB signaling to modulate blood vessel inflammation

Cardiovascular diseases such as atherosclerosis are one of the leading causes of morbidity and mortality worldwide. The clinical manifestations of atherosclerosis, which include heart attack and stroke, occur several decades after initiation of the disease and become more severe with age. Inflammation of blood vessels plays a prominent role in atherogenesis. Activation of the endothelium by inflammatory mediators leads to the recruitment of circulating inflammatory cells, which drives atherosclerotic plaque formation and progression. Inflammatory signaling within the endothelium is driven predominantly by the pro-inflammatory transcription factor, NF-κB. Interestingly, activation of NF-κB is enhanced during the normal aging process and this may contribute to the development of cardiovascular disease. Importantly, studies utilizing mouse models of vascular inflammation and atherosclerosis are uncovering a network of noncoding RNAs, particularly microRNAs, which impinge on the NF-κB signaling pathway. Here we summarize the literature regarding the control of vascular inflammation by microRNAs, and provide insight into how these microRNA-based pathways might be harnessed for therapeutic treatment of disease. We also discuss emerging areas of endothelial cell biology, including the involvement of long noncoding RNAs and circulating microRNAs in the control of vascular inflammation.

TIA1 interacts with annexin A7 in regulating vascular endothelial cell autophagy

T-cell intracellular antigen-1 (TIA1) is a DNA/RNA binding protein broadly expressed in eukaryotic cells, participating in multiple aspects of cellular metabolism. TIA1 phosphorylation was related with cell apoptosis and its RNA binding activity, however, the regulator and other functions of TIA1 phosphorylation were very little known. To find the modulator of TIA1 phosphorylation, we performed yeast two-hybrid screening and identified annexin A7 (ANXA7) as an interaction protein of TIA1. Recent study showed that a small molecule ABO could directly target ANXA7 and inhibit ANXA7 activity and its targets' phosphorylation. As a GTPase, ANXA7 was speculated to modulate TIA1 phosphorylation. Our results showed that ABO treatment promoted the interaction between TIA1 and ANXA7, and then greatly inhibited phosphorylation of TIA1 in HUVECs. Further results showed that ABO-increased interaction between ANXA7 and TIA1 significantly promoted the processing of a pro-autophagic factor FLJ11812 and the expression of ATG13. Moreover, we found that ABO increased TIA1 protein level, co-localization of ANXA7 and TIA1, and ATG13 expression in the aortic endothelium of apoE(-/-) mice. These data highlighted the new role of TIA1 phosphorylation in autophagy.

Autophagy in Huntington disease and huntingtin in autophagy

Autophagy is an important biological process that is essential for the removal of damaged organelles and toxic or aggregated proteins by delivering them to the lysosome for degradation. Consequently, autophagy has become a primary target for the treatment of neurodegenerative diseases that involve aggregating proteins. In Huntington disease (HD), an expansion of the polyglutamine (polyQ) tract in the N-terminus of the huntingtin (HTT) protein leads to protein aggregation. However, HD is unique among the neurodegenerative proteinopathies in that autophagy is not only dysfunctional but wild type (wt) HTT also appears to play several roles in regulating the dynamics of autophagy. Herein, we attempt to integrate the recently described novel roles of wtHTT and altered autophagy in HD.

An activator of mTOR inhibits oxLDL-induced autophagy and apoptosis in vascular endothelial cells and restricts atherosclerosis in apolipoprotein E⁻/⁻ mice

Oxidized low-density lipoprotein (oxLDL) inhibits mammalian target of rapamycin (mTOR) and induces autophagy and apoptosis in vascular endothelial cells (VECs) that play very critical roles for the cardiovascular homostasis. We recently defined 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) as a new activator of mTOR. Therefore, we hypothesized that 3BDO had a protective role in VECs and thus stabilized atherosclerotic lesions in apolipoprotein E^-/- (apoE^-/-) mice. Our results showed that oxLDL inhibited the activity of mTOR and increased the protein level of autophagy-related 13 (ATG13) and its dephosphorylation, thus inducing autophagy in human umbilical vein endothelial cells (HUVECs). All of these effects were strongly inhibited by 3BDO. In vivo experiments confirmed that 3BDO activated mTOR and decreased the protein level of ATG13 in the plaque endothelium of apoE^-/- mice. Importantly, 3BDO did not affect the activity of mTOR and autophagy in macrophage cell line RAW246.7 and vascular smooth muscle cells of apoE^-/- mice, but suppressed plaque endothelial cell death and restricted atherosclerosis development in the mice. 3BDO protected VECs by activating mTOR and thus stabilized atherosclerotic lesions in apoE^-/- mice.