Novel Role of miR-33 in Regulating of Mitochondrial Function

The functions of immune system-derived miRNAs in cardiovascular diseases

Cardiovascular diseases (CVD) are the foremost cause of mortality worldwide, with recent advances in immunology underscoring the critical roles of immune cells in their onset and progression. MicroRNAs (miRNAs), particularly those derived from the immune system, have emerged as vital regulators of cellular functions within the cardiovascular landscape. This review focuses on "immuno-miRs," a class of miRNAs that are highly expressed in immune cells, including T cells, B cells, NK cells, neutrophils, and monocytes/macrophages, and their significant role in controlling immune signaling pathways. Highlighting recent studies in human and animal models, this review examines how miRNAs influence both innate and adaptive immune responses and explores their potential as therapeutic targets for CVD. Special emphasis is placed on miRNAs that regulate T cells, suggesting that targeted manipulation of these miRNA pathways could offer new strategies for CVD treatment. As research in cardiovascular immunology advances, this review aims to provide a thorough overview of the potential of immune system-derived miRNAs to revolutionize CVD management and therapy, addressing a major global health challenge.

MicroRNA-33 regulates the synaptic plasticity-related gene ARC in temporal lobe epilepsy

This study aimed to elucidate the expression patterns of miR-33 and ARC in both a rat model of temporal lobe epilepsy (TLE) and human TLE patients, to explore the role of miR-33 in epilepsy onset through its regulation of ARC expression in the hippocampus. Our findings, supported by a Dual-Luciferase reporter assay, suggest that miR-33 can bind to the 3' UTR region of ARC. We observed that miR-33 levels were reduced at 1 hour and 60 days post-seizure, while ARC expression notably increased at these time points. In the hippocampal CA1 and CA3 regions of post-seizure rats, ARC expression significantly exceeded that of control groups. Following the transfection of HEK cells with a miR-33 mimic, there was a decrease in both ARC mRNA and protein levels, whereas the group treated with a miR-33 inhibitor displayed the opposite effect. RNA sequencing in TLE patients revealed a similar miR-33 and ARC interaction. The regulation of Arc expression by miR-33 suggests that Arc may be a target gene of miR-33 in the context of epilepsy. Our findings indicate that miR-33 downregulation could contribute to the dysregulation of Arc expression observed in TLE, potentially influencing the disease process. Further studies are required to establish the exact role of miR-33-mediated Arc regulation in the development of epilepsy.

miR-33 deletion in hepatocytes attenuates MASLD-MASH-HCC progression

The complexity of the mechanisms underlying metabolic dysfunction-associated steatotic liver disease (MASLD) progression remains a significant challenge for the development of effective therapeutics. miRNAs have shown great promise as regulators of biological processes and as therapeutic targets for complex diseases. Here, we study the role of hepatic miR-33, an important regulator of lipid metabolism, during the progression of MASLD and the development of hepatocellular carcinoma (HCC). We report that miR-33 was elevated in the livers of humans and mice with MASLD and that its deletion in hepatocytes (miR-33 HKO) improved multiple aspects of the disease, including steatosis and inflammation, limiting the progression to metabolic dysfunction-associated steatotic hepatitis (MASH), fibrosis, and HCC. Mechanistically, hepatic miR-33 deletion reduced lipid synthesis and promoted mitochondrial fatty acid oxidation, reducing lipid burden. Additionally, absence of miR-33 altered the expression of several known miR-33 target genes involved in metabolism and resulted in improved mitochondrial function and reduced oxidative stress. The reduction in lipid accumulation and liver injury resulted in decreased YAP/TAZ pathway activation, which may be involved in the reduced HCC progression in HKO livers. Together, these results suggest suppressing hepatic miR-33 may be an effective therapeutic approach to temper the development of MASLD, MASH, and HCC in obesity.

Oestrogen receptor positive breast cancer and its embedded mechanism: breast cancer resistance to conventional drugs and related therapies, a review

Traditional medication and alternative therapies have long been used to treat breast cancer. One of the main problems with current treatments is that there is an increase in drug resistance in the cancer cells owing to genetic differences such as mutational changes, epigenetic changes and miRNA (microRNA) alterations such as miR-1246, miR-298, miR-27b and miR-33a, along with epigenetic modifications, such as Histone3 acetylation and CCCTC-Binding Factor (CTCF) hypermethylation for drug resistance in breast cancer cell lines. Certain forms of conventional drug resistance have been linked to genetic changes in genes such as ABCB1, AKT, S100A8/A9, TAGLN2 and NPM. This review aims to explore the current approaches to counter breast cancer, the action mechanism, along with novel therapeutic methods endowing potential drug resistance. The investigation of novel therapeutic approaches sheds light on the phenomenon of drug resistance including genetic variations that impact distinct forms of oestrogen receptor (ER) cancer, genetic changes, epigenetics-reported resistance and their identification in patients. Long-term effective therapy for breast cancer includes selective oestrogen receptor modulators, selective oestrogen receptor degraders and genetic variations, such as mutations in nuclear genes, epigenetic modifications and miRNA alterations in target proteins. Novel research addressing combinational therapies including maytansine, photodynamic therapy, guajadiol, talazoparib, COX2 inhibitors and miRNA 1246 inhibitors have been developed to improve patient survival rates.

microRNA-33 deficiency in macrophages enhances autophagy, improves mitochondrial homeostasis, and protects against lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal disease. Recent findings have shown a marked metabolic reprogramming associated with changes in mitochondrial homeostasis and autophagy during pulmonary fibrosis. The microRNA-33 (miR-33) family of microRNAs (miRNAs) encoded within the introns of sterol regulatory element binding protein (SREBP) genes are master regulators of sterol and fatty acid (FA) metabolism. miR-33 controls macrophage immunometabolic response and enhances mitochondrial biogenesis, FA oxidation, and cholesterol efflux. Here, we show that miR-33 levels are increased in bronchoalveolar lavage (BAL) cells isolated from patients with IPF compared with healthy controls. We demonstrate that specific genetic ablation of miR-33 in macrophages protects against bleomycin-induced pulmonary fibrosis. The absence of miR-33 in macrophages improves mitochondrial homeostasis and increases autophagy while decreasing inflammatory response after bleomycin injury. Notably, pharmacological inhibition of miR-33 in macrophages via administration of anti-miR-33 peptide nucleic acids (PNA-33) attenuates fibrosis in different in vivo and ex vivo mice and human models of pulmonary fibrosis. These studies elucidate a major role of miR-33 in macrophages in the regulation of pulmonary fibrosis and uncover a potentially novel therapeutic approach to treat this disease.

Hepatocyte-specific miR-33 deletion attenuates NAFLD-NASH-HCC progression

The complexity of the multiple mechanisms underlying non-alcoholic fatty liver disease (NAFLD) progression remains a significant challenge for the development of effective therapeutics. miRNAs have shown great promise as regulators of biological processes and as therapeutic targets for complex diseases. Here, we study the role of hepatic miR-33, an important regulator of lipid metabolism, during the progression of NAFLD. We report that miR-33 is overexpressed in hepatocytes isolated from mice with NAFLD and demonstrate that its specific suppression in hepatocytes (miR-33 HKO ) improves multiple aspects of the disease, including insulin resistance, steatosis, and inflammation and limits the progression to non-alcoholic steatohepatitis (NASH), fibrosis and hepatocellular carcinoma (HCC). Mechanistically, we find that hepatic miR-33 deficiency reduces lipid biosynthesis and promotes mitochondrial fatty acid oxidation to reduce lipid burden in hepatocytes. Additionally, miR-33 deficiency improves mitochondrial function, reducing oxidative stress. In miR-33 deficient hepatocytes, we found an increase in AMPKα activation, which regulates several pathways resulting in the attenuation of liver disease. The reduction in lipid accumulation and liver injury resulted in decreased transcriptional activity of the YAP/TAZ pathway, which may be involved in the reduced progression to HCC in the HKO livers. Together, these results suggest suppressing hepatic miR-33 may be an effective therapeutic approach at different stages of NAFLD/NASH/HCC disease progression.

In Vitro Investigations of miR-33a Expression in Estrogen Receptor-Targeting Therapies in Breast Cancer Cells

(1) Background: Increased fatty acid synthesis leads to the aggressive phenotype of breast cancer and renders efficiency of therapeutics. Regulatory microRNAs (miRNAs) on lipid biosynthesis pathways as miR-33a have potential to clarify the exact mechanism. (2) Methods: We determined miR-33a expression levels following exposure of MCF-7 and MDA-MB-231 breast cancer cells to estrogen receptor (ER) activator (estradiol-17β, E2) or anti-estrogens (ICI 182,780, Fulvestrant, FUL) at non-cytotoxic concentrations. We related miR-33a expression levels in the cells to cellular lipid biosynthesis-related pathways through immunoblotting. (3) Results: miR-33a mimic treatment led to significantly downregulation of fatty acid synthase (FASN) in MCF-7 cells but not in MDA-MB-231 cells in the presence of estradiol-17β (E2) or Fulvestrant (FUL). In contrast to the miR-33a inhibitor effect, miR-33a mimic co-transfection with E2 or FUL led to diminished AMP-activated protein kinase α (AMPKα) activity in MCF-7 cells. E2 increases FASN levels in MDA-MB-231 cells regardless of miR-33a cellular levels. miR-33a inhibitor co-treatment suppressed E2-mediated AMPKα activity in MDA-MB-231 cells. (4) Conclusions: The cellular expression levels of miR-33a are critical to understanding differential responses which include cellular energy sensors such as AMPKα activation status in breast cancer cells.

Experimental Study on the Compatibility and Characteristics of a Dual-Target Microbubble Loaded with Anti-miR-33

Objective

To prepare a new type of dual-target microbubble loaded with anti-miR-33 (ANM33).

Methods

Carrier core nanobubbles (NBs) were prepared by thin film hydration, and microbubbles loaded with PM1 (PCNBs) were prepared by grafting DSPE-PEG2000-maleimide-PM1 onto the NB surface. ANM33 was connected via electrostatic adsorption and covalent bonding, and hyaluronic acid (HA) was covalently connected. PM1 and HA were the targets, and ANM33 was the intervention drug. To evaluate the general physical and chemical properties of the prepared dual-target microbubbles loaded with ANM33 (HA-PANBs), we observed their morphology, particle size and surface potential while monitoring their stability and in vitro imaging ability, evaluated their toxic effect on cells and verified their ability to target cells.

Results

HA-PANBs had a regular morphology and good stability. The average particle size measured by a Malvern potentiometer was 1421.75±163.23 nm, and the average surface potential was −5.51±1.87 mV. PM1 and ANM33 were effectively connected to the NBs. The PM1, ANM33, and HA binding reached 89.0±1.1%, 65.02±5.0%, and 61.4±3.5%, respectively, and the maximum binding reached 2 µg, 5 µg, and 7 µg/10⁸ microbubbles, respectively. HA-PANBs had no obvious toxic effects on cells, and their ability to continuously enhance imaging in vitro persisted for more than 15 minutes, obviously targeting foam cells in the early stage of AS.

Conclusion

HA-PANBs are ideal ultrasound contrast agents. The successful, firm connection of PM1 and HA to the NBs significantly increased the amount of carried ANM33. When microbubbles prepared with 2:4:7 PM1:ANM33:HA were used as a contrast agent, they had a high ANM33 carrying capacity, stable physical properties, and significantly enhanced imaging and targeting of foam cells in the early stage of AS.

miR-33-3p Regulates PC12 Cell Proliferation and Differentiation In Vitro by Targeting Slc29a1

MicroRNA-33-3p (miR-33-3p) has been widely investigated for its roles in lipid metabolism and mitochondrial function; however, there are few studies on miR-33-3p in the context of neurological diseases. In this study, we investigated the functional role of miR-33-3p in rat pheochromocytoma PC12 cells. A miR-33-3p mimic was transduced into PC12 cells, and its effects on proliferation, apoptosis, and differentiation were studied using the MTS assay, EdU labeling, flow cytometry, qRT-PCR, western blot, ELISA, and immunofluorescence. We found that miR-33-3p significantly suppressed PC12 cell proliferation, but had no effect on apoptosis. Furthermore, miR-33-3p promoted the differentiation of PC12 cells into Tuj1-positive and choline acetyltransferase-positive neuron-like cells. Mechanistically, miR-33-3p repressed the expression of Slc29a1 in PC12 cells. Importantly, knocking down Slc29a1 in PC12 cells inhibited proliferation and induced differentiation into neuron-like cells. In conclusion, this study showed that miR-33-3p regulated Slc29a1, which in turn controlled the proliferation and differentiation of PC12 cells. Thus, we hypothesize that the miR-33-3p/Slc29a1 axis could be a promising therapeutic target for recovering neurons and the cholinergic nervous system.

MicroRNA-33/33* inhibit the activation of MAVS through AMPK in antiviral innate immunity

Innate immunity plays a prominent role in the host defense against pathogens and must be precisely regulated. As vital orchestrators in cholesterol homeostasis, microRNA-33/33* have been widely investigated in cellular metabolism. However, their role in antiviral innate immunity is largely unknown. Here, we report that VSV stimulation decreased the expression of miR-33/33* through an IFNAR-dependent manner in macrophages. Overexpression of miR-33/33* resulted in impaired RIG-I signaling, enhancing viral load and lethality whereas attenuating type I interferon production both in vitro and in vivo. In addition, miR-33/33* specifically prevented the mitochondrial adaptor mitochondrial antiviral-signaling protein (MAVS) from forming activated aggregates by targeting adenosine monophosphate activated protein kinase (AMPK), subsequently impeding the mitophagy-mediated elimination of damaged mitochondria and disturbing mitochondrial homeostasis which is indispensable for efficient MAVS activation. Our findings establish miR-33/33* as negative modulators of the RNA virus-triggered innate immune response and identify a previously unknown regulatory mechanism linking mitochondrial homeostasis with antiviral signaling pathways.

MiR-33a Controls hMSCS Osteoblast Commitment Modulating the Yap/Taz Expression Through EGFR Signaling Regulation

Mesenchymal stromal cells (hMSCs) display a pleiotropic function in bone regeneration. The signaling involved in osteoblast commitment is still not completely understood, and that determines the failure of current therapies being used. In our recent studies, we identified two miRNAs as regulators of hMSCs osteoblast differentiation driving hypoxia signaling and cytoskeletal reorganization. Other signalings involved in this process are epithelial to mesenchymal transition (EMT) and epidermal growth factor receptor (EGFR) signalings through the regulation of Yes-associated protein (YAP)/PDZ-binding motif (TAZ) expression. In the current study, we investigated the role of miR-33a family as a (i) modulator of YAP/TAZ expression and (ii) a regulator of EGFR signaling during osteoblast commitments. Starting from the observation on hMSCs and primary osteoblast cell lines (Nh-Ost) in which EMT genes and miR-33a displayed a specific expression, we performed a gain and loss of function study with miR-33a-5p and 3p on hMSCs cells and Nh-Ost. After 24 h of transfections, we evaluated the modulation of EMT and osteoblast genes expression by qRT-PCR, Western blot, and Osteoimage assays. Through bioinformatic analysis, we identified YAP as the putative target of miR-33a-3p. Its role was investigated by gain and loss of function studies with miR-33a-3p on hMSCs; qRT-PCR and Western blot analyses were also carried out. Finally, the possible role of EGFR signaling in YAP/TAZ modulation by miR-33a-3p expression was evaluated. Human MSCs were treated with EGF-2 and EGFR inhibitor for different time points, and qRT-PCR and Western blot analyses were performed. The above-mentioned methods revealed a balance between miR-33a-5p and miR-33a-3p expression during hMSCs osteoblast differentiation. The human MSCs phenotype was maintained by miR-33a-5p, while the maintenance of the osteoblast phenotype in the Nh-Ost cell model was permitted by miR-33a-3p expression, which regulated YAP/TAZ through the modulation of EGFR signaling. The inhibition of EGFR blocked the effects of miR-33a-3p on YAP/TAZ modulation, favoring the maintenance of hMSCs in a committed phenotype. A new possible personalized therapeutic approach to bone regeneration was discussed, which might be mediated by customizing delivery of miR-33a in simultaneously targeting EGFR and YAP signaling with combined use of drugs.

Tanshinone IIA reduces oxidized low-density lipoprotein-induced inflammatory responses by downregulating microRNA-33 in THP-1 macrophages

Atherosclerosis is a leading cause of cardiovascular diseases. Oxidized low-density lipoprotein (ox-LDL) is commonly used to construct atherosclerosis cell models. Macrophages-secreted pro-inflammatory factors play vital roles in the development of atherosclerosis. Tanshinone IIA (Tan) is an effective therapeutic agent for atherosclerotic cardiovascular diseases. However, the molecular mechanisms by which Tan protects against atherogenesis have not been thoroughly elucidated. In the present study, we aimed to search for microRNA targets of Tan in ox-LDL-stimulated macrophages. Interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) levels were determined by matching ELISA commercial kits. RT-qPCR assay was conducted to measure microRNA-33 (miR-33) expression. We found that ox-LDL induced the secretion of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and the expression of microRNA-33 (miR-33) in THP-1 macrophages. Tan inhibited pro-inflammatory cytokine secretion and miR-33 expression in ox-LDL-stimulated THP-1 macrophages. Also, the depletion of miR-33 suppressed pro-inflammatory cytokine secretion in ox-LDL-stimulated THP-1 macrophages. Moreover, miR-33 upregulation abrogated the inhibitory effect of Tan on pro-inflammatory cytokine secretion in ox-LDL-stimulated THP-1 macrophages. In conclusion, Tan inhibited ox-LDL-induced pro-inflammatory cytokine secretion by downregulating miR-33 in THP-1 macrophages, hinting that Tan might exert its atheroprotective effects by targeting miR-33 and reducing pro-inflammatory responses.

Novel Insights in the Metabolic Syndrome-induced Oxidative Stress and Inflammation-mediated Atherosclerosis

Context:

Atherosclerosis is a progressive pathological process and a leading cause of mor-tality worldwide. Clinical research and epidemiological studies state that atherosclerosis is caused by an amalgamation of metabolic and inflammatory deregulation involving three important pathological events including Endothelial Dysfunction (ED), Foam Cell Formation (FCF), and Vascular Smooth Muscle Cells (VSMCs) proliferation and migration.

Objectives:

Research in recent years has identified Metabolic Syndrome (MS), which involves factors such as obesity, insulin resistance, dyslipidemia and diabetes, to be responsible for the pathophysiol-ogy of atherosclerosis. These factors elevate oxidative stress and inflammation-induced key signalling molecules and various microRNAs (miRs). In present study, we have reviewed recently identified molecular targets in the pathophysiology of atherosclerosis.

Methods:

Scientific literature obtained from databases such as university library, PubMed and Google along with evidences from published experimental work in relevant journals has been sum-marized in this review article.

Results:

The molecular events and cell signalling implicated in atherogenic processes of ED, FCF and VSMCs hyperplasia are sequential and progressive, and involve cross talks at many levels. Specific molecules such as transcription factors, inflammatory cytokines and chemokines and miRs have been identified playing crucial role in most of the events leading to atherosclerosis.

Conclusion:

Studies associated with MS induced oxidative stress- and inflammation- mediated sig-nalling pathways along with critical miRs help in better understanding of the pathophysiology of ath-erosclerosis. Several key molecules discussed in this review could be potent target for the prevention and treatment of atherosclerosis.

Osteoblast-targeted delivery of miR-33-5p attenuates osteopenia development induced by mechanical unloading in mice

A growing body of evidence has revealed that microRNAs (miRNAs) play crucial roles in regulating osteoblasts and bone metabolism. However, the effects of miRNAs in osteoblast mechanotransduction remain to be defined. In this study, we investigated the regulatory effect of miR-33-5p in osteoblasts and tested its anti-osteopenia effect when delivered by an osteoblast-targeting delivery system in vivo. First, we demonstrated that miR-33-5p could promote the activity and mineralization of osteoblasts without influencing their proliferation in vitro. Then our data showed that supplementing miR-33-5p in osteoblasts by a targeted delivery system partially recovered the osteopenia induced by mechanical unloading at the biochemical, microstructural, and biomechanical levels. In summary, our findings demonstrate that miR-33-5p is a key factor in the occurrence and development of the osteopenia induced by mechanical unloading. In addition, targeted delivery of the mimics of miR-33-5p is a promising new strategy for the treatment of pathological osteopenia.

Ogg1-Dependent DNA Repair Regulates NLRP3 Inflammasome and Prevents Atherosclerosis

RATIONALE

Activation of NLRP3 (nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3) inflammasome-mediating interleukin (IL)-1β secretion has emerged as an important component of inflammatory processes in atherosclerosis. Mitochondrial DNA (mtDNA) damage is detrimental in atherosclerosis, and mitochondria are central regulators of the nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 inflammasome. Human atherosclerotic plaques express increased mtDNA damage. The major DNA glycosylase, 8-oxoguanine glycosylase (OGG1), is responsible for removing the most abundant form of oxidative DNA damage.

OBJECTIVE

To test the role of OGG1 in the development of atherosclerosis in mouse.

METHODS AND RESULTS

We observed that Ogg1 expression decreases over time in atherosclerotic lesion macrophages of low-density lipoprotein receptor (Ldlr) knockout mice fed a Western diet. Ogg1(-/-)Ldlr(-/-) mice fed a Western diet resulted in an increase in plaque size and lipid content. We found increased oxidized mtDNA, inflammasome activation, and apoptosis in atherosclerotic lesions and also higher serum IL-1β and IL-18 in Ogg1(-/-)Ldlr(-/-) mice than in Ldlr(-/-). Transplantation with Ogg1(-/-) bone marrow into Ldlr(-/-) mice led to larger atherosclerotic lesions and increased IL-1β production. However, transplantation of Ogg1(-/-)Nlrp3(-/-) bone marrow reversed the Ogg1(-/-) phenotype of increased plaque size. Ogg1(-/-) macrophages showed increased oxidized mtDNA and had greater amounts of cytosolic mtDNA and cytochrome c, increased apoptosis, and more IL-1β secretion. Finally, we found that proatherogenic miR-33 can directly inhibit human OGG1 expression and indirectly suppress both mouse and human OGG1 via AMP-activated protein kinase.

CONCLUSIONS

OGG1 plays a protective role in atherogenesis by preventing excessive inflammasome activation. Our study provides insight into a new target for therapeutic intervention based on a link between oxidative mtDNA damage, OGG1, and atherosclerosis via NLRP3 inflammasome.

Common links between metabolic syndrome and inflammatory bowel disease: Current overview and future perspectives

Metabolic syndrome (MS) features a constellation of central obesity, dyslipidemia, impaired glucose metabolism and often hypertension joined by insulin resistance and chronic inflammation. All these elements greatly raise patient's risk of cardiovascular disease and type 2 diabetes, resulting in an increased mortality. Metabolic syndrome affects approximately 20-25% of the world's adult population and thus it is essential to study its pathophysiology and seek new pharmacological targets. There is a thoroughly studied link between MS and inflammatory diseases of the gastrointestinal (GI) system, i.e. steatohepatitis. However, recent findings also indicate similarities in pathophysiological features between MS and inflammatory bowel disease (IBD), including adipose tissue dysregulation, inadequate immune response, and inflammation. In this review we aim to outline the pathophysiology of MS and emphasize the aspects revealed recently, such as mineralocorticoid activity, involvement of sex hormones and an accompanying increase in prolactin secretion. More importantly, we focus on the common links between MS and IBD. Finally, we describe new strategies and drug targets that may be utilized in MS therapy, namely adiponectin mimetics, GLP-1-based multi agonists, ABCA1 agonists and possible role of miRNA. We also discuss the possible utility of selected agents as adjuvants in IBD therapy.