Differential RNA expression profiles and competing endogenous RNA-associated regulatory networks during the progression of atherosclerosis

HMOX1-LDHB interaction promotes ferroptosis by inducing mitochondrial dysfunction in foamy macrophages during advanced atherosclerosis

Advanced atherosclerosis is the pathological basis for acute cardiovascular events, with significant residual risk of recurrent clinical events despite contemporary treatment. The death of foamy macrophages is a main contributor to plaque progression, but the underlying mechanisms remain unclear. Bulk and single-cell RNA sequencing demonstrated that massive iron accumulation in advanced atherosclerosis promoted foamy macrophage ferroptosis, particularly in low expression of triggering receptor expressed on myeloid cells 2 (TREM2low) foamy macrophages. This cluster exhibits metabolic characteristics with low oxidative phosphorylation (OXPHOS), increasing ferroptosis sensitivity. Mechanically, upregulated heme oxygenase 1 (HMOX1)-lactate dehydrogenase B (LDHB) interaction enables Lon peptidase 1 (LONP1) to degrade mitochondrial transcription factor A (TFAM), leading to mitochondrial dysfunction and ferroptosis. Administration of the mitochondria-targeted reactive oxygen species (ROS) scavenger MitoTEMPO (mitochondrial-targeted TEMPO) or LONP1 inhibitor bortezomib restored mitochondrial homeostasis in foamy macrophages and alleviated atherosclerosis. Collectively, our study elucidates the cellular and molecular mechanism of foamy macrophage ferroptosis, offering potential therapeutic strategies for advanced atherosclerosis.

Role of long non-coding RNA TCONS_02443383 in regulating cell adhesion and peroxisome proliferator-activated receptor (PPAR) signaling genes in atherosclerosis: A New Zealand white rabbit model study

OBJECTIVE

In this study, we performed RNA sequencing (RNA-seq) on the abdominal aorta tissue of New Zealand rabbits and investigated the potential association of lncRNA TCONS_02443383 with the development of AS through bioinformatics analysis of the sequencing data. The obtained results were further validated using quantitative real-time polymerase chain reaction (qRT-PCR).

METHOD

We induced an AS model in New Zealand rabbits by causing balloon injury to the abdominal aorta vascular wall and administering a high-fat diet. We then upregulated the expression level of the lncRNA TCONS_02443383 by injecting lentiviral plasmids through the ear vein. RNA sequencing (RNA-seq) was performed on the abdominal aorta tissues. We conducted Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway and Gene Ontology (GO) analyses.

RESULT

The overexpression of the lncRNA TCONS_02443383 led to an upregulation of peroxisome proliferator-activated receptor (PPAR) signaling pathways as well as genes related to cell adhesion.

CONCLUSION

The overexpression of the lncRNA TCONS_02443383 can inhibit the occurrence and development of AS by upregulating peroxisome proliferator-activated receptor (PPAR) signaling pathways and genes related to cell adhesion.

Caspase-11 deficiency attenuates neutrophil recruitment into the atherosclerotic lesion in apolipoprotein E-deficient mice

Caspase-11 is an inflammatory caspase that triggers an inflammatory response by regulating non-canonical NLRP3 inflammasome activation. Although the deficiency of both caspase-11 and caspase-1, another inflammatory caspase that functions as an executor of the inflammasome, prevents the development of atherosclerosis, the effect of caspase-11 deficiency alone on the development of atherosclerosis has not been fully evaluated. In the present study, we found that caspase-11 deficiency prevented the formation of the necrotic core, whereas it did not affect the development of atherosclerosis in Apoe-deficient mice. Notably, the infiltration of neutrophils into atherosclerotic lesions was attenuated by caspase-11 deficiency. RNA-seq analysis of stage-dependent expression of atherosclerotic lesions revealed that both upregulations of caspase-11 and neutrophil migration are common features of advanced atherosclerotic lesions. Furthermore, similar expression profiles were observed in unstable human plaque. These data suggest that caspase-11 regulates neutrophil recruitment and plaque destabilization in advanced atherosclerotic lesions.

Long Noncoding RNA Gpr137b-ps Promotes Advanced Atherosclerosis via the Regulation of Autophagy in Macrophages

BACKGROUND

Current therapies cannot completely reverse advanced atherosclerosis. High levels of amino acids, induced by Western diet, stimulate mTORC1 (mammalian target of rapamycin complex 1)-autophagy defects in macrophages, accelerating atherosclerotic plaque progression. In addition, autophagy-lysosomal dysfunction contributes to plaque necrotic core enlargement and lipid accumulation. Therefore, it is essential to investigate the novel mechanism and molecules to reverse amino acid-mTORC1-autophagy signaling dysfunction in macrophages of patients with advanced atherosclerosis.

METHODS

We observed that Gpr137b-ps (G-protein-coupled receptor 137B, pseudogene) was upregulated in advanced atherosclerotic plaques. The effect of Gpr137b-ps on the progression of atherosclerosis was studied by generating advanced plaques in ApoE-/- mice with cardiac-specific knockout of Gpr137b-ps. Bone marrow-derived macrophages and mouse mononuclear macrophage cell line RAW264.7 cells were subjected to starvation or amino acid stimulation to study amino acid-mTORC1-autophagy signaling. Using both gain- and loss-of-function approaches, we explored the mechanism of Gpr137b-ps-regulated autophagy.

RESULTS

Our results demonstrated that Gpr137b-ps deficiency led to enhanced autophagy in macrophages and reduced atherosclerotic lesions, characterized by fewer necrotic cores and less lipid accumulation. Knockdown of Gpr137b-ps increased autophagy and prevented amino acid-induced mTORC1 signaling activation. As the downstream binding protein of Gpr137b-ps, HSC70 (heat shock cognate 70) rescued the impaired autophagy induced by Gpr137b-ps. Furthermore, Gpr137b-ps interfered with the HSC70 binding to G3BP (Ras GTPase-activating protein-binding protein), which tethers the TSC (tuberous sclerosis complex) complex to lysosomes and suppresses mTORC1 signaling. In addition to verifying that the NTF2 (nuclear transport factor 2) domain of G3BP binds to HSC70 by in vitro protein synthesis, we further demonstrated that HSC70 binds to the NTF2 domain of G3BP through its W90-F92 motif by using computational modeling.

CONCLUSIONS

These findings reveal that Gpr137b-ps plays an essential role in the regulation of macrophage autophagy, which is crucial for the progression of advanced atherosclerosis. Gpr137b-ps impairs the interaction of HSC70 with G3BP to regulate amino acid-mTORC1-autophagy signaling, and these results provide a new potential therapeutic direction for the treatment of advanced atherosclerosis.

RNA Sequencing Reveals the Differentially Expressed circRNAs between Stable and Unstable Carotid Atherosclerotic Plaques

Objective. This study aimed to identify circular RNA profiles (circRNAs) via high-throughput RNA sequencing and distinguish the differentially expressed (DE) circRNAs between stable and unstable plaques. Methods. RNA sequencing was performed on unstable and stable carotid plaque samples obtained from patients with carotid artery stenosis. DE circRNAs were screened, and six DE circRNAs were verified using quantitative real-time PCR (qRT-PCR). Functional evaluation of the DE circRNAs was conducted via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Results. We screened 344 DE circRNAs in unstable plaques, consisting of 342 upregulated and 2 downregulated circRNAs. GO analysis showed that the host genes of the upregulated circRNAs were related to ER to Golgi transport vesicle membrane, endocytic vesicle membrane, and Ran GTPase binding. KEGG analysis revealed that the host genes of the upregulated circRNAs were primarily associated with protein processing in endoplasmic reticulum, lysine degradation, homologous recombination, epithelial cell signaling in Helicobacter pylori infection, and yersinia infection. The results of qRT-PCR verified three upregulated DE circRNAs and two downregulated DE circRNAs in unstable plaques. Conclusion. Hsa-circ-0001523, hsa-circ-0008950, hsa-circ-0000571, hsa-circ-0001946, and hsa-circ-0000745 may be involved in regulating the stability of atherosclerotic plaques and serves as a therapeutic target for unstable plaques.

Mmu_circ_0000271 regulated the growth of ox-LDL-stimulated mouse vascular smooth muscle cells via sponging miR-5123

BACKGROUND

Atherosclerosis (AS) is a complex inflammatory disease of the arterial wall. Mmu_circ_0000271 was found to be aberrantly expressed in AS, but its function and mechanism in AS have not been reported.

OBJECTIVE

This study investigated the role of mmu_circ_0000271 in AS.

METHODS

Mmu_circ_0000271 were identified using UCSC website, RNase R treatment, and nuclear‑cytoplasmic extraction. And mouse vascular smooth muscle cells (VSMCs) were used to establish the AS cell model by treating oxidized low-density lipoprotein (ox-LDL, 50 μg/ml). Next, the expression of circ_0000271 in VSMCs was determined by quantitative real-time PCR. The effect of overexpressed or silenced circ_0000271 on ox-LDL-treated VSMCs viability, angiogenesis and invasion were detected by MTT, tube formation and transwell assays. The proteins expressions of proliferative and migratory markers were measured by western blot. After the target relationship predication between circ_0000271 and miR-5123, these experiments were performed again to evaluate the effect of miR-5123 inhibitor on AS model cells.

RESULTS

Mmu_circ_0000271 was stably and highly expressed in ox-LDL-treated VSMCs, and its expression was enriched in the cell cytoplasm. Circ_0000271 overexpression further promoted the ox-LDL-induced viability, angiogenesis and invasion, as well as the proliferation- and migration-related proteins in VSMCs, whereas circ_0000271 knockdown had the opposite effect. Moreover, circ_0000271 was found to target miR-5123 and circ_0000271 overexpression suppressed its expression. And miR-5123 inhibitor was capable of reversing the effect of shcirc_0000271 on AS model cells.

CONCLUSION

Mmu_circ_0000271 regulated ox-LDL-induced VSMC proliferation and migration through bind to miR-5123, and it could serve as a potential biomarker for AS.

Profile and Functional Prediction of Plasma Exosome-Derived CircRNAs From Acute Ischemic Stroke Patients

Stroke is one of the major causes of death and long-term disability, of which acute ischemic stroke (AIS) is the most common type. Although circular RNA (circRNA) expression profiles of AIS patients have been reported to be significantly altered in blood and peripheral blood mononuclear cells, the role of exosome-containing circRNAs after AIS is still unknown. Plasma exosomes from 10 AIS patients and 10 controls were isolated, and through microarray and bioinformatics analysis, the profile and putative function of circRNAs in the plasma exosomes were studied. A total of 198 circRNAs were differentially quantified (|log2 fold change| ≥ 1.00, p < 0.05) between AIS patients and controls. The levels of 12 candidate circRNAs were verified by qRT-PCR, and the quantities of 10 of these circRNAs were consistent with the data of microarray. The functions of host genes of differentially quantified circRNAs, including RNA and protein process, focal adhesion, and leukocyte transendothelial migration, were associated with the development of AIS. As a miRNA sponge, differentially quantified circRNAs had the potential to regulate pathways related to AIS, like PI3K-Akt, AMPK, and chemokine pathways. Of 198 differentially quantified circRNAs, 96 circRNAs possessing a strong translational ability could affect cellular structure and activity, like focal adhesion, tight junction, and endocytosis. Most differentially quantified circRNAs were predicted to bind to EIF4A3 and AGO2—two RNA-binding proteins (RBPs)—and to play a role in AIS. Moreover, four of ten circRNAs with verified levels by qRT-PCR (hsa_circ_0112036, hsa_circ_0066867, hsa_circ_0093708, and hsa_circ_0041685) were predicted to participate in processes of AIS, including PI3K-Akt, AMPK, and chemokine pathways as well as endocytosis, and to be potentially useful as diagnostic biomarkers for AIS. In conclusion, plasma exosome-derived circRNAs were significantly differentially quantified between AIS patients and controls and participated in the occurrence and progression of AIS by sponging miRNA/RBPs or translating into proteins, indicating that circRNAs from plasma exosomes could be crucial molecules in the pathogenesis of AIS and promising candidates as diagnostic biomarkers and therapeutic targets for the condition.