Novel Therapeutic Potential of Retinoid-Related Orphan Receptor α in Cardiovascular Diseases

Parent-of-Origin Effects in Childhood Asthma at Seven Years of Age

Childhood asthma is more common among children whose mothers have asthma than among those whose fathers have asthma. The reasons for this are unknown, and we hypothesize that genomic imprinting may partly explain this observation. Our aim is to assess parent-of-origin (PoO) effects on childhood asthma by analyzing SNP array genotype data from a large population-based cohort. To estimate PoO effects in parent-reported childhood asthma at 7 years of age, we fit a log-linear model implemented in the HAPLIN R package to SNP array genotype data from 915 mother-father-child case triads, 603 mother-child case dyads, and 113 father-child case dyads participating in the Norwegian Mother, Father, and Child Cohort Study (MoBa). We found that alleles at two SNPs-rs3003214 and rs3003211-near the adenylosuccinate synthase 2 gene (ADSS2 on chromosome 1q44) showed significant PoO effects at a false positive rate ≤ 0.05. The ratio of the effect of the maternally and paternally inherited G-allele at rs3003214 was 1.68 (95% CI: 1.41-2.03, p value = 1.13E-08). Our results suggest PoO effects at the ADSS2 gene, particularly the maternally inherited G-allele at rs3003214, may contribute to the maternal effect in childhood asthma.

RORA Regulates Autophagy in Hair Follicle Stem Cells by Upregulating the Expression Level of the Sqstm1 Gene

The hair coat is an adaptive evolutionary trait unique to mammals, aiding them in adapting to complex environmental challenges. Although some of the factors involved in regulating hair follicle development have been characterized, further in-depth research is still needed. Retinoic acid receptor-related orphan receptor alpha (RORA), as a member of the nuclear receptor family, is highly involved in the regulation of cellular states. Previous studies have shown that autophagy plays a significant role in hair follicle development. This study uses rat hair follicle stem cells (HFSCs) as a model to analyze the impact of RORA on the autophagy levels of HFSCs. Upon activation of RORA, autophagy indicators such as the LC3-II/LC3-I ratio and MDC staining significantly increased, suggesting an elevated level of autophagy in HFSCs. Following treatment with chloroquine, the LC3-II/LC3-I ratio, as well as the expression levels of BECN1 protein and SQSTM1 protein, were markedly elevated in the cells, indicating that the autophagic flux was unobstructed and ruling out the possibility that RORA activation impeded autophagy. Additionally, the level of the Sqstm1 gene increased markedly after RORA activation promoted autophagy in the cells. We found that RORA regulates the transcription level of Sqstm1 by binding to its promoter region. We believe that RORA activation significantly promotes the level of autophagy, particularly selective autophagy, in HFSCs, suggesting that RORA has the potential to become a new target for research on hair follicle development. This research provides a theoretical foundation for studies on hair follicle development and also offers new insights for the treatment of diseases such as alopecia.

Roles of retinoic acid-related orphan receptor α in high glucose-induced cardiac fibroblasts proliferation

Diabetic cardiomyopathy, characterized by myocardial fibrosis, is a common complication of diabetes. Retinoic acid-related orphan receptor α (RORα) participates in various pathological and physiological cardiovascular processes. The current research aims to elucidate the roles and mechanisms of RORα in high glucose induced cardiac fibroblasts proliferation. Primary neonatal cardiac fibroblasts were isolated from Sprague-Dawley rats, and pre-administrated with RORα antagonist SR3335 (20 µM) or RORα agonist SR1078 (10 µM) followed by the stimulation with normal glucose (5.5 mM) or high glucose (33.3 mM) respectively. Lactate Dehydrogenase (LDH) release into culture medium, cellular adenosine-triphosphate (ATP), and cell number were detected. Expressions of Collagen I, Collagen III, proliferating cell nuclear antigen (PCNA), α-smooth muscle actin (α-SMA), receptor-interacting protein kinase 1 (RIPK1) and receptor-interacting protein kinase 3 (RIPK3) were evaluated. The extent of oxidative stress was also assessed. Our study found that high glucose elevated LDH release, reduced cellular ATP production, increased cells numbers, elevated expression of Collagen I, Collagen III, PCNA, α-SMA, RIPK1 and RIPK3, decreased mitochondrial membrane potential, strengthened intensity of dihydroethidium (DHE) and MitoSOX fluorescence. Above effects were all further exacerbated by SR3335 but significantly reversed by SR1078. In conclusion, RORα antagonist SR3335 promoted cell injury and proliferation, enhanced collagen synthesis, facilitated oxidative stress and necroptosis in cardiac fibroblasts with high glucose stimulation, whereas RORα agonist SR1078 showed opposing effects. Our study proposed RORα as a novel target against high glucose-induced cardiac fibroblasts proliferation, which is beneficial to clarify ideal therapeutic implication for diabetic cardiomyopathy.

Retinoic acid receptor-related orphan receptor alpha and synthetic RORα agonist against invasion and metastasis in tongue squamous cell carcinoma

Retinoic acid receptor-related orphan receptor alpha (RORα), an essential tumor suppressor in a range of human malignancies, is classified as a member of the orphan nuclear receptor family. The most prevalent form of oral cancer, tongue squamous cell carcinoma (TSCC) is characterized by its severe malignancy and unfavorable prognosis. However, the extent to which its tumorigenesis mechanisms are associated with RORα expression levels is still not fully understood. The objective of this study was to examine the molecular mechanisms by which RORα is involved in TSCC. Through the use of immunohistochemistry (IHC), it was discovered that the expression level of RORα was significantly downregulated in TSCC tissues when compared to adjacent normal tissues in this study. To further investigate the role of RORα in TSCC, we activated the expression of RORα in human TSCC cell line (SCC9 cells) by transfecting RORα cDNA and using the selective RORα agonist SR1078. The results show that RORα can significantly inhibit the invasion, migration, proliferation, and adhesion of TSCC cells and induce cell apoptosis. In addition, xenograft models confirmed the conclusion that stable activation or treatment with SR1078 to increase RORα content significantly inhibited tumor growth and development. Taken together, this study provides solid evidence for the inhibitory role of RORα in the progression of TSCC. In addition, the preliminary application results of SR1078 in TSCC show that SR1078 is expected to be a potential therapeutic medication for TSCC. These findings provide innovative perspectives on the development of potential biomarkers and agents for TSCC therapy. The objective is to introduce novel strategy and alternatives for the prevention and treatment of TSCC.

Roles of distinct nuclear receptors in diabetic cardiomyopathy

Diabetes mellitus induces a pathophysiological disorder known as diabetic cardiomyopathy and may eventually cause heart failure. Diabetic cardiomyopathy is manifested with systolic and diastolic contractile dysfunction along with alterations in unique cardiomyocyte proteins and diminished cardiomyocyte contraction. Multiple mechanisms contribute to the pathology of diabetic cardiomyopathy, mainly including abnormal insulin metabolism, hyperglycemia, glycotoxicity, cardiac lipotoxicity, endoplasmic reticulum stress, oxidative stress, mitochondrial dysfunction, calcium treatment damage, programmed myocardial cell death, improper Renin-Angiotensin-Aldosterone System activation, maladaptive immune modulation, coronary artery endothelial dysfunction, exocrine dysfunction, etc. There is an urgent need to investigate the exact pathogenesis of diabetic cardiomyopathy and improve the diagnosis and treatment of this disease. The nuclear receptor superfamily comprises a group of transcription factors, such as liver X receptor, retinoid X receptor, retinoic acid-related orphan receptor-α, retinoid receptor, vitamin D receptor, mineralocorticoid receptor, estrogen-related receptor, peroxisome proliferatoractivated receptor, nuclear receptor subfamily 4 group A 1(NR4A1), etc. Various studies have reported that nuclear receptors play a crucial role in cardiovascular diseases. A recently conducted work highlighted the function of the nuclear receptor superfamily in the realm of metabolic diseases and their associated complications. This review summarized the available information on several important nuclear receptors in the pathophysiology of diabetic cardiomyopathy and discussed future perspectives on the application of nuclear receptors as targets for diabetic cardiomyopathy treatment.

Sevoflurane alleviates inflammation, apoptosis and permeability damage of human umbilical vein endothelial cells induced by lipopolysaccharide by inhibiting endoplasmic reticulum stress via upregulating RORα

Endothelial dysfunction often accompanies sepsis. Sevoflurane (Sev) is a widely used inhaled anesthetic that has a protective effect on sepsis-associated damage. We aimed to elucidate the role of Sev in endothelial dysfunction by using a model of LPS induced HUVECs. Sev increased the viability and decreased the apoptosis of HUVECs exposed to LPS. Inflammation and endothelial cell adhesion were improved after Sev addition. Besides, Sev alleviated LPS-induced endothelial cell permeability damage in HUVECs. RORα served as a potential protein that bound to Sev. Importantly, Sev upregulated RORα expression and inhibited endoplasmic reticulum (ER) stress in LPS-treated HUVECs. RORα silencing reversed the impacts of Sev on ER stress. Moreover, RORα deficiency or tunicamycin (ER stress inducer) treatment restored the effects of Sev on the viability, apoptosis, inflammation and endothelial permeability damage of HUVECs exposed to LPS. Taken together, Sev ameliorated LPS-induced endothelial cell damage by targeting RORα to inhibit ER stress.

Circadian regulation of Ca V 1.2 expression by RORα in the mouse heart

Background

In addition to show autonomous beating rhythmicity, the physiological functions of the heart present daily periodic oscillations. Notably the ventricular repolarization itself varies throughout the circadian cycle which was mainly related to the periodic expression of K + channels. However, the involvement of the L-type Ca 2+ channel (Ca V 1.2 encoded by Cacna1c gene) in these circadian variations remains elusive.

Methods

We used a transgenic mouse model (PCa-luc) that expresses the luciferase reporter under the control of the cardiac Cacna1c promoter and analyzed promoter activity by bioluminescent imaging, qPCR, immunoblot, Chromatin immunoprecipitation assay (ChIP) and Ca V 1.2 activity.

Results

Under normal 12:12h light-dark cycle, we observed in vivo a biphasic diurnal variation of promoter activities peaking at 9 and 19.5 Zeitgeber time (ZT). This was associated with a periodicity of Cacna1c mRNA levels preceding 24-h oscillations of Ca V 1.2 protein levels in ventricle (with a 1.5 h phase shift) but not in atrial heart tissues. The periodicity of promoter activities and Ca V 1.2 proteins, which correlated with biphasic oscillations of L-type Ca 2+ current conductance, persisted in isolated ventricular cardiomyocytes from PCa-Luc mice over the course of the 24-h cycle, suggesting an endogenous cardiac circadian regulation. Comparison of 24-h temporal patterns of clock gene expressions in ventricles and atrial tissues of the same mice revealed conserved circadian oscillations of the core clock genes except for the retinoid-related orphan receptor α gene (RORα), which remained constant throughout the course of a day in atrial tissues. In vitro we found that RORα is recruited to two specific regions on the Cacna1c promoter and that incubation with specific RORα inhibitor disrupted 24-h oscillations of ventricular promoter activities and Ca V 1.2 protein levels. Similar results were observed for pore forming subunits of the K + transient outward currents, K V 4.2 and K V 4.3.

Conclusions

These findings raise the possibility that the RORα-dependent rhythmic regulation of cardiac Ca V 1.2 and K V 4.2/4.3 throughout the daily cycle may play an important role in physiopathology of heart function.

Hydrogen sulfide promoted retinoic acid-related orphan receptor α transcription to alleviate diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is one serious and common complication in diabetes without effective treatments. Hydrogen sulfide (H2S) fights against a variety of cardiovascular diseases including DCM. Retinoic acid-related orphan receptor α (RORα) has protective effects on cardiovascular system. However, whether RORα mediates the protective effect of H2S against DCM remains unknown. The present research was to explore the roles and mechanisms of RORα in H2S against DCM. The study demonstrated that H2S donor sodium hydrosulfide (NaHS) alleviated cell injury but enhanced RORα expression in high glucose (HG)-stimulated cardiomyocytes. However, NaHS no longer had the protective effect on attenuating cell damage and oxidative stress, improving mitochondrial membrane potential, inhibiting necroptosis and enhanced signal transducer and activator of transcription 3 (STAT3) Ser727 phosphorylation in HG-stimulated cardiomyocytes after RORα siRNA transfection. Moreover, NaHS improved cardiac function, attenuated myocardial hypertrophy and fibrosis, alleviated oxidative stress, inhibited necroptosis, but increased STAT3 phosphorylation in wild type (WT) mice but not in RORα knockout mice (a spontaneous staggerer mice, sg/sg mice) with diabetes. Additionally, NaHS increased RORα promoter activity in cardiomyocytes with HG stimulation, which was related to the binding sites of E2F transcription factor 1 (E2F1) in the upstream region of RORα promoter. NaHS enhanced E2F1 expression and increased the binding of E2F1 to RORα promoter in cardiomyocytes with HG stimulation. In sum, H2S promoted RORα transcription via E2F1 to alleviate necroptosis and protect against DCM. It is helpful to propose a novel therapeutic implication for DCM.