ORAI1 Ca2+ Channel as a Therapeutic Target in Pathological Vascular Remodelling

House dust mite allergens induce Ca2+ signalling and alarmin responses in asthma airway epithelial cells

Type 2 inflammation in asthma develops with exposure to stimuli to include inhaled allergens from house dust mites (HDM). Features include mucus hypersecretion and the formation of pro-secretory ion transport characterised by elevated basal Cl- current. Studies using human sinonasal epithelial cells treated with HDM extract report a higher protease activated receptor-2 (PAR-2) agonist-induced calcium mobilisation that may be related to airway sensitisation by allergen-associated proteases. Herein, this study aimed to investigate the effect of HDM on Ca2+ signalling and inflammatory responses in asthmatic airway epithelial cells. Primary bronchial epithelial cells (hPBECs) from asthma donors cultured at air-liquid interface were used to assess electrophysiological, Ca2+ signalling and inflammatory responses. Differences were observed regarding Ca2+ signalling in response to PAR-2 agonist 2-Furoyl-LIGRLO-amide (2-FLI), and equivalent short-circuit current (Ieq) in response to trypsin and 2-FLI, in ALI-asthma and healthy hPBECs. HDM treatment led to increased levels of intracellular cations (Ca2+, Na+) and significantly reduced the 2-FLI-induced change of Ieq in asthma cells. Apical HDM-induced Ca2+ mobilisation was found to mainly involve the activation of PAR-2 and PAR-4-associated store-operated Ca2+ influx and TRPV1. In contrast, PAR-2, PAR-4 antagonists and TRPV1 antagonist only showed slight impact on basolateral HDM-induced Ca2+ mobilisation. HDM trypsin-like serine proteases were the main components leading to non-amiloride sensitive Ieq and also increased interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP) from asthma hPBECs. These studies add further insight into the complex mechanisms associated with HDM-induced alterations in cell signalling and their relevance to pathological changes within asthma.

ORAI Ca2+ Channels in Cancers and Therapeutic Interventions

The ORAI proteins serve as crucial pore-forming subunits of calcium-release-activated calcium (CRAC) channels, pivotal in regulating downstream calcium-related signaling pathways. Dysregulated calcium homeostasis arising from mutations and post-translational modifications in ORAI can lead to immune disorders, myopathy, cardiovascular diseases, and even cancers. Small molecules targeting ORAI present an approach for calcium signaling modulation. Moreover, emerging techniques like optogenetics and optochemistry aim to offer more precise regulation of ORAI. This review focuses on the role of ORAI in cancers, providing a concise overview of their significance in the initiation and progression of cancers. Additionally, it highlights state-of-the-art techniques for ORAI channel modulation, including advanced optical tools, potent pharmacological inhibitors, and antibodies. These novel strategies offer promising avenues for the functional regulation of ORAI in research and may inspire innovative approaches to cancer therapy targeting ORAI.

Inhibition of adenylyl cyclase 8 prevents the upregulation of Orai1 channel, which improves cardiac function after myocardial infarction

The upregulation of Orai1 and subsequent store-operated Ca2+ entry (SOCE) has been associated with adverse cardiac remodeling and heart failure (HF). However, the mechanism underlying Orai1 upregulation and its role in myocardial infarction remains unclear. Our study investigated the role of Orai1 in activating adenylyl cyclase 8 (AC8) and cyclic AMP (cAMP) response element-binding protein (CREB), as well as its contribution to cardiac dysfunction induced by ischemia and reperfusion (I/R). We found that I/R evoked an increase in the expression of Orai1 and AC8 in rats' hearts, resulting in a substantial rise in diastolic Ca2+ concentration ([Ca2+]i), and reduced ventricular contractions. The expression of Orai1 and AC8 was also increased in ventricular biopsies of post-ischemic HF patients. Mechanistically, we demonstrate that I/R activation of Orai1 stimulated AC8, which produced cAMP and phosphorylated CREB. Subsequently, p-CREB activated the ORAI1 promoter, resulting in Orai1 upregulation and SOCE exacerbation. Intramyocardial administration of AAV9 carrying AC8 short hairpin RNA decreased the expression of AC8, Orai1 and CREB, which restored diastolic [Ca2+]i and improved cardiac contraction. Therefore, our data suggests that the axis composed by Orai1/AC8/CREB plays a critical role in I/R-induced cardiac dysfunction, representing a potential new therapeutic target to limit the progression of the disease toward HF.

ORAI1 inhibition as an efficient preclinical therapy for tubular aggregate myopathy and Stormorken syndrome

Tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK) are clinically overlapping disorders characterized by childhood-onset muscle weakness and a variable occurrence of multisystemic signs, including short stature, thrombocytopenia, and hyposplenism. TAM/STRMK is caused by gain-of-function mutations in the Ca2+ sensor STIM1 or the Ca2+ channel ORAI1, both of which regulate Ca2+ homeostasis through the ubiquitous store-operated Ca2+ entry (SOCE) mechanism. Functional experiments in cells have demonstrated that the TAM/STRMK mutations induce SOCE overactivation, resulting in excessive influx of extracellular Ca2+. There is currently no treatment for TAM/STRMK, but SOCE is amenable to manipulation. Here, we crossed Stim1R304W/+ mice harboring the most common TAM/STRMK mutation with Orai1R93W/+ mice carrying an ORAI1 mutation partially obstructing Ca2+ influx. Compared with Stim1R304W/+ littermates, Stim1R304W/+Orai1R93W/+ offspring showed a normalization of bone architecture, spleen histology, and muscle morphology; an increase of thrombocytes; and improved muscle contraction and relaxation kinetics. Accordingly, comparative RNA-Seq detected more than 1,200 dysregulated genes in Stim1R304W/+ muscle and revealed a major restoration of gene expression in Stim1R304W/+Orai1R93W/+ mice. Altogether, we provide physiological, morphological, functional, and molecular data highlighting the therapeutic potential of ORAI1 inhibition to rescue the multisystemic TAM/STRMK signs, and we identified myostatin as a promising biomarker for TAM/STRMK in humans and mice.

Side-by-side comparison of published small molecule inhibitors against thapsigargin-induced store-operated Ca2+ entry in HEK293 cells

Calcium (Ca2+) is a key second messenger in eukaryotes, with store-operated Ca2+ entry (SOCE) being the main source of Ca2+ influx into non-excitable cells. ORAI1 is a highly Ca2+-selective plasma membrane channel that encodes SOCE. It is ubiquitously expressed in mammals and has been implicated in numerous diseases, including cardiovascular disease and cancer. A number of small molecules have been identified as inhibitors of SOCE with a variety of potential therapeutic uses proposed and validated in vitro and in vivo. These encompass both nonselective Ca2+ channel inhibitors and targeted selective inhibitors of SOCE. Inhibition of SOCE can be quantified both directly and indirectly with a variety of assay setups, making an accurate comparison of the activity of different SOCE inhibitors challenging. We have used a fluorescence based Ca2+ addback assay in native HEK293 cells to generate dose-response data for many published SOCE inhibitors. We were able to directly compare potency. Most compounds were validated with only minor and expected variations in potency, but some were not. This could be due to differences in assay setup relating to the mechanism of action of the inhibitors and highlights the value of a singular approach to compare these compounds, as well as the general need for biorthogonal validation of novel bioactive compounds. The compounds observed to be the most potent against SOCE in our study were: 7-azaindole 14d (12), JPIII (17), Synta-66 (6), Pyr 3 (5), GSK5503A (8), CM4620 (14) and RO2959 (7). These represent the most promising candidates for future development of SOCE inhibitors for therapeutic use.

[Research advances in genetic polymorphisms in Kawasaki disease]

Kawasaki disease (KD) is a systemic inflammatory vascular disorder that predominantly affects children and is the leading cause of acquired heart disease in children. Although the etiology of this disease remains unclear, genome-wide association and genome-wide linkage studies have shown that some susceptible genes and chromosomal regions are associated with the development and progression of KD. With the advancement of high-throughput DNA sequencing techniques, more and more genomic information related to KD is being discovered. Understanding the genes involved in the pathogenesis of KD may provide novel insights into the diagnosis and treatment of KD. By analyzing related articles and summarizing related research advances, this article mainly discusses the T cell activation-enhancing genes that have been confirmed to be closely associated with the development and progression of KD and reveals their association with the pathogenesis of KD and coronary artery lesions.

Anti-Inflammatory Effects of Alphitolic Acid Isolated from Agrimonia coreana Nakai Extracts Are Mediated via the Inhibition of ICRAC Activity in T Cells

Agrimonia pilosa Ledeb., an important medicinal herb in traditional East Asian medicine, is primarily used to treat abdominal pain, dysentery, and hemostasis. There are ten other reported species of Agrimonia plants, including Agrimonia coreana Nakai-a naturally growing species in South Korea-and Agrimonia eupatoria Linn. Although recent studies have isolated numerous active constituents and investigated their effects, the medicinal utility of this herb is not yet fully explored. Through patch-clamp recording, a previous study reported that Agrimonia plant extracts inhibit the function of Ca2+ release-activated Ca2+ channels (CRACs). Herein, we aimed to identify and isolate the main compounds in A. coreana responsible for CRAC inhibition while assessing the anti-inflammatory effects mediated by this inhibition. We demonstrated for the first time that alphitolic acid isolated from A. coreana has a dose-dependent inhibitory effect on CRAC activity and, thus, an inhibitory effect on intracellular calcium increase. Furthermore, analysis of human CD4+ T cell proliferation via the carboxyfluorescein diacetate succinimidyl ester method revealed that alphitolic acid inhibited T cell proliferation in a concentration-dependent manner. Our findings provide a theoretical basis for the potential therapeutic use of alphitolic acid in the treatment of inflammatory diseases.

Receptor Tyrosine Kinase: Still an Interesting Target to Inhibit the Proliferation of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) proliferation is a critical event that contributes to the pathogenesis of vascular remodeling such as hypertension, restenosis, and pulmonary hypertension. Increasing evidences have revealed that VSMCs proliferation is associated with the activation of receptor tyrosine kinases (RTKs) by their ligands, including the insulin-like growth factor receptor (IGFR), fibroblast growth factor receptor (FGFR), epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR). Moreover, some receptor tyrosinase inhibitors (TKIs) have been found and can prevent VSMCs proliferation to attenuate vascular remodeling. Therefore, this review will describe recent research progress on the role of RTKs and their inhibitors in controlling VSMCs proliferation, which helps to better understand the function of VSMCs proliferation in cardiovascular events and is beneficial for the prevention and treatment of vascular disease.

Upregulation of Orai Channels Contributes to Aging-Related Vascular Alterations in Rat Coronary Arteries

Vascular territories display heterogeneous sensitivity to the impacts of aging. The relevance of the STIM/Orai system to vascular function depends on the vascular bed. We aimed to evaluate the contribution of the STIM/Orai system to aging-related vascular dysfunction in rat coronary circulation. Vascular function was evaluated according to myography in coronary arteries from young (three-month-old) and older (twenty-month-old) rats. The effects of aging and STIM/Orai inhibition on the contraction and relaxation of the coronary arteries and on the protein expression of STIM-1, Orai1, and Orai3 in these vessels were determined. Aging-related hypercontractility to serotonin and endothelin-1 in arteries from male rats was reversed by STIM/Orai inhibition with YM-58483 or by specifically blocking the Orai1 channel with Synta66. The inhibitory effects of Synta66 on coronary vasoconstriction were also observed in older female rats. YM-58483 relaxed serotonin- but not KCl-contracted arteries from males. STIM/Orai inhibition improved defective endothelial vasodilations in aged arteries, even in the presence of NO synthase and cyclooxygenase inhibitors, but not in KCl-contracted segments. YM-58483 significantly enhanced relaxations to calcium-activated potassium channel stimulation in aged vessels. Increased protein expression of Orai1 and Orai3 was detected in arterial homogenates and sections from older rats. Upregulation of the Orai channel contributes to aging-related coronary dysfunction, revealing a potential target in reducing CVD risk.

Diversity and complexity of cell death: a historical review

Death is the inevitable fate of all living organisms, whether at the individual or cellular level. For a long time, cell death was believed to be an undesirable but unavoidable final outcome of nonfunctioning cells, as inflammation was inevitably triggered in response to damage. However, experimental evidence accumulated over the past few decades has revealed different types of cell death that are genetically programmed to eliminate unnecessary or severely damaged cells that may damage surrounding tissues. Several types of cell death, including apoptosis, necrosis, autophagic cell death, and lysosomal cell death, which are classified as programmed cell death, and pyroptosis, necroptosis, and NETosis, which are classified as inflammatory cell death, have been described over the years. Recently, several novel forms of cell death, namely, mitoptosis, paraptosis, immunogenic cell death, entosis, methuosis, parthanatos, ferroptosis, autosis, alkaliptosis, oxeiptosis, cuproptosis, and erebosis, have been discovered and advanced our understanding of cell death and its complexity. In this review, we provide a historical overview of the discovery and characterization of different forms of cell death and highlight their diversity and complexity. We also briefly discuss the regulatory mechanisms underlying each type of cell death and the implications of cell death in various physiological and pathological contexts. This review provides a comprehensive understanding of different mechanisms of cell death that can be leveraged to develop novel therapeutic strategies for various diseases.

Purinergic Activation of Store-Operated Calcium Entry (SOCE) Regulates Cell Migration in Metastatic Ovarian Cancer Cells

Store-operated calcium entry (SOCE) is an important process in calcium signaling. Its role in physiological and pathological events is well recognized. However, in cancerous systems, the importance of SOCE in relation to the degree of cancer aggressiveness, as well as its regulation by ligands such as purinergic molecules, are not well documented. This study aimed to characterize a differential effect of the P2Y2 receptor (promoted by UTP of 10 µM and inhibited by ARC118925XX of 1 µM) on intracellular calcium response between metastatic (SKOV-3) and non-metastatic (CAOV-3) ovarian cell lines in conditions of normal (1.5 mM) and zero extracellular calcium concentration. The sustained calcium influx observed exclusively in SKOV-3 cells was associated with the presence of SOCE (promoted by thapsigargin (74.81 ± 0.94 ΔF) and sensitive to 2-APB (20.60 ± 0.85 ΔF)), whereas its absence in CAOV-3 cells (26.2 ± 6.1 ΔF) was correlated with a low expression of ORAI1. The relevance of SOCE in metastatic SKOV-3 cells was further corroborated when 2-APB significantly inhibited (40.4 ± 2.8% of covered area) UTP-induced cell migration (54.6 ± 3.7% of covered area). In conclusion, our data suggest that SOCE activation elicited by the P2Y2 receptor is involved in the aggressiveness of ovarian cancer cells.

Too much of a good thing: The case of SOCE in cellular apoptosis

Intracellular calcium (Ca2+) is an essential second messenger in eukaryotic cells regulating numerous cellular functions such as contraction, secretion, immunity, growth, and metabolism. Ca2+ signaling is also a key signal transducer in the intrinsic apoptosis pathway. The store-operated Ca2+ entry pathway (SOCE) is ubiquitously expressed in eukaryotic cells, and is the primary Ca2+ influx pathway in non-excitable cells. SOCE is mediated by the endoplasmic reticulum Ca2+ sensing STIM proteins, and the plasma membrane Ca2+-selective Orai channels. A growing number of studies have implicated SOCE in regulating cell death primarily via the intrinsic apoptotic pathway in a variety of tissues and in response to physiological stressors such as traumatic brain injury, ischemia reperfusion injury, sepsis, and alcohol toxicity. Notably, the literature points to excessive cytosolic Ca2+ influx through SOCE in vulnerable cells as a key factor tipping the balance towards cellular apoptosis. While the literature primarily addresses the functions of STIM1 and Orai1, STIM2, Orai2 and Orai3 are also emerging as potential regulators of cell death. Here, we review the functions of STIM and Orai proteins in regulating cell death and the implications of this regulation to human pathologies.

Interruption of TRPC6-NFATC1 signaling inhibits NADPH oxidase 4 and VSMCs phenotypic switch in intracranial aneurysm

Intracranial aneurysm (IA) is a frequent cerebrovascular disorder with unclear pathogenesis. The vascular smooth muscle cells (VSMCs) phenotypic switch is essential for IA formation. It has been reported that Ca2+ overload and excessive reactive oxygen species (ROS) are involved in VSMCs phenotypic switch. The transient receptor potential canonical 6 (TRPC6) and NADPH oxidase 4 (NOX4) are the main pathway to participate in Ca2+ overload and ROS production in VSMCs. Ca2+ overload can activate calcineurin (CN), leading to nuclear factor of activated T cell (NFAT) dephosphorylation to regulate the target gene's transcription. We hypothesized that activation of TRPC6-NFATC1 signaling may upregulate NOX4 and involve in VSMCs phenotypic switch contributing to the progression of IA. Our results showed that the expressions of NOX4, p22phox, p47phox, TRPC6, CN and NFATC1 were significantly increased, and VSMCs underwent a significant phenotypic switch in IA tissue and cellular specimens. The VIVIT (NFATC1 inhibitor) and BI-749327 (TRPC6 inhibitor) treatment reduced the expressions of NOX4, p22phox and p47phox and the production of ROS, and significantly improved VSMCs phenotypic switch in IA rats and cells. Consistent results were obtained from IA Trpc6 knockout (Trpc6-/-) mice. Furthermore, the results also revealed that NFATC1 could regulate NOX4 transcription by binding to its promoter. Our findings reveal that interrupting the TRPC6-NFATC1 signaling inhibits NOX4 and improves VSMCs phenotypic switch in IA, and regulating Ca2+ homeostasis may be an important therapeutic strategy for IA.

ORAI Calcium Channels: Regulation, Function, Pharmacology, and Therapeutic Targets

The changes in intracellular free calcium (Ca2+) levels are one of the most widely regulators of cell function; therefore, calcium as a universal intracellular mediator is involved in very important human diseases and disorders. In many cells, Ca2+ inflow is mediated by store-operated calcium channels, and it is recognized that the store-operated calcium entry (SOCE) is mediated by the two partners: the pore-forming proteins Orai (Orai1-3) and the calcium store sensor, stromal interaction molecule (STIM1-2). Importantly, the Orai/STIM channels are involved in crucial cell signalling processes such as growth factors, neurotransmitters, and cytokines via interaction with protein tyrosine kinase coupled receptors and G protein-coupled receptors. Therefore, in recent years, the issue of Orai/STIM channels as a drug target in human diseases has received considerable attention. This review summarizes and highlights our current knowledge of the Orai/STIM channels in human diseases and disorders, including immunodeficiency, myopathy, tubular aggregate, Stormorken syndrome, York platelet syndrome, cardiovascular and metabolic disorders, and cancers, as well as suggesting these channels as drug targets for pharmacological therapeutic intervention. Moreover, this work will also focus on the pharmacological modulators of Orai/STIM channel complexes. Together, our thoughtful of the biology and physiology of the Orai/STIM channels have grown remarkably during the past three decades, and the next important milestone in the field of store-operated calcium entry will be to identify potent and selective small molecules as a therapeutic agent with the purpose to target human diseases and disorders for patient benefit.

STIM/Orai Inhibition as a Strategy for Alleviating Diabetic Erectile Dysfunction Through Modulation of Rat and Human Penile Tissue Contractility and in vivo Potentiation of Erectile Responses

BACKGROUND

Stromal interaction molecule (STIM)/Orai calcium entry system appears to have a role in erectile dysfunction (ED) pathophysiology but its specific contribution to diabetic ED was not elucidated.

AIM

To evaluate STIM/Orai inhibition on functional alterations associated with diabetic ED in rat and human penile tissues and on in vivo erectile responses in diabetic rats.

METHODS

Rat corpus cavernosum (RCC) strips from nondiabetic (No DM) and streptozotocin-induced diabetic (DM) rats and human penile resistance arteries (HPRA) and corpus cavernosum (HCC) from ED patients undergoing penile prosthesis insertion were functionally evaluated in organ chambers and wire myographs. Erectile function in vivo in rats was assessed by intracavernosal pressure (ICP) responses to cavernous nerve electrical stimulation (CNES). Expression of STIM/Orai elements in HCC was determined by immunofluorescence and immunoblot.

MAIN OUTCOME MEASURES

Functional responses in RCC, HCC and HPRA and STIM/Orai protein expression in HCC. In vivo erectile responses to CNES.

RESULTS

Inhibition of Orai channels with YM-58483 (20 µM) significantly reduced adrenergic contractions in RCC but more effectively in DM. Thromboxane-induced and neurogenic contractions were reduced by STIM/Orai inhibition while defective endothelial, neurogenic and PDE5 inhibitor-induced relaxations were enhanced by YM-58483 (10 µM) in RCC from DM rats. In vivo, YM-58483 caused erections and attenuated diabetes-related impairment of erectile responses. YM-58483 potentiated the effects of PDE5 inhibition. In human tissues, STIM/Orai inhibition depressed adrenergic and thromboxane-induced contractions in ED patients more effectively in those with type 2 diabetes. Diabetes was associated with increased expression of Orai1 and Orai3 in ED patients.

CLINICAL TRANSLATION

Targeting STIM/Orai to alleviate diabetes-related functional alterations of penile vascular tissue could improve erectile function and potentiate therapeutic effects of PDE5 inhibitors in diabetic ED.

STRENGTHS AND LIMITATIONS

Improving effects of STIM/Orai inhibition on diabetes-related functional impairment was evidenced in vitro and in vivo in an animal model and validated in human tissues from ED patients. Functional findings were complemented with expression results. Main limitation was low numbers of human experiments due to limited human tissue availability.

CONCLUSIONS

STIM/Orai inhibition alleviated alterations of functional responses in vitro and improved erectile responses in vivo in diabetic rats, potentiating the effects of PDE5 inhibition. STIM/Orai inhibition was validated as a target to modulate functional alterations of human penile vascular tissue in diabetic ED where Orai1 and Orai3 channels were upregulated. STIM/Orai inhibition could be a potential therapeutic strategy to overcome poor response to conventional ED therapy in diabetic patients. Sevilleja-Ortiz A, El Assar M, García-Gómez B, et al. STIM/Orai Inhibition as a Strategy for Alleviating Diabetic Erectile Dysfunction Through Modulation of Rat and Human Penile Tissue Contractility and in vivo Potentiation of Erectile Responses. J Sex Med 2022;19:1733-1749.

CRACking the Molecular Regulatory Mechanism of SOCE during Platelet Activation in Thrombo-Occlusive Diseases

Thrombo-occlusive diseases such as myocardial infarction, ischemic stroke and deep vein thrombosis with subsequent pulmonary embolism still represent a major health burden worldwide. Besides the cells of the vasculature or other hematopoietic cells, platelets are primarily responsible for the development and progression of an occluding thrombus. The activation and function of platelets crucially depend on free cytosolic calcium (Ca2+) as second messenger, which modulates platelet secretion, aggregation and thrombus formation. Ca2+ is elevated upon platelet activation by release of Ca2+ from intracellular stores thus triggering of the subsequent store-operated Ca2+ entry (SOCE), which is facilitated by Ca2+ release-activated channels (CRACs). In general, CRACs are assembled by the pore-forming unit Orai in the plasma membrane and the Ca2+-sensing stromal interaction molecule (STIM) in the endoplasmic reticulum after the depletion of internal Ca2+ stores. In the last few years, there is a growing body of the literature demonstrating the importance of STIM and Orai-mediated mechanism in thrombo-occlusive disorders. Thus, this review provides an overview of the recent understanding of STIM and Orai signaling in platelet function and its implication in the development and progression of ischemic thrombo-occlusive disorders. Moreover, potential pharmacological implications of STIM and Orai signaling in platelets are anticipated and discussed in the end.

Role of Store-Operated Ca2+ Entry in the Pulmonary Vascular Remodeling Occurring in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe and multifactorial disease. PAH pathogenesis mostly involves pulmonary arterial endothelial and pulmonary arterial smooth muscle cell (PASMC) dysfunction, leading to alterations in pulmonary arterial tone and distal pulmonary vessel obstruction and remodeling. Unfortunately, current PAH therapies are not curative, and therapeutic approaches mostly target endothelial dysfunction, while PASMC dysfunction is under investigation. In PAH, modifications in intracellular Ca2+ homoeostasis could partly explain PASMC dysfunction. One of the most crucial actors regulating Ca2+ homeostasis is store-operated Ca2+ channels, which mediate store-operated Ca2+ entry (SOCE). This review focuses on the main actors of SOCE in human and experimental PASMC, their contribution to PAH pathogenesis, and their therapeutic potential in PAH.

Ageing-induced hypercontractility is related to functional enhancement of STIM/Orai and upregulation of Orai 3 in rat and human penile tissue

The role of STIM/Orai calcium entry system on vascular ageing has not been elucidated. We aimed to evaluate the influence of ageing on STIM/Orai signalling and its role on ageing-induced alterations of contractile function in rat corpus cavernosum (RCC) and human penile resistance arteries (HPRA) and corpus cavernosum (HCC). RCC was obtained from 3 months-old and 20 months-old animals. HPRA and HCC were obtained from organ donors of varied ages without history of erectile dysfunction. Aging was associated with enhanced norepinephrine (NE)- and thromboxane analogue (U46619)-induced contractions in RCC which were significantly inhibited by the STIM/Orai inhibitor, YM-58483 (20 μM). Other STIM/Orai inhibitor, 2-aminoethyldiphenylborate also reduced NE-induced contractions in RCC from aged rats. YM-58483 significantly reduced neurogenic contractions and potentiated neurogenic relaxations in RCC from aged rats. In HCC and HPRA, NE-induced contractions were significantly enhanced in older subjects (>65 years-old) but YM-58483 completely reversed ageing-related hypercontractility. Ageing did not modify STIM-1 and Orai1 protein expressions but Orai3 was significantly overexpressed in cavernosal tissue from old rats and older subjects. Contribution of STIM/Orai to cavernosal contraction increases with ageing together with increased expression of Orai3. Orai inhibition could be a potential therapeutic strategy to reduce ageing-related impact on vascular/erectile function.