Long non-coding RNA AK085865 ablation confers susceptibility to viral myocarditis by regulating macrophage polarization

M2 macrophage exosome-derived lncRNA AK083884 protects mice from CVB3-induced viral myocarditis through regulating PKM2/HIF-1α axis mediated metabolic reprogramming of macrophages

Viral myocarditis (VM) is a clinically common inflammatory disease. Accumulating literature has indicated that M2 macrophages protect mice from Coxsackievirus B3 (CVB3)-induced VM. However, mechanisms that underlie M2 macrophages alleviating myocardial inflammation remain largely undefined. We found that M2 macrophage-derived exosomes (M2-Exo) can effectively attenuate VM. The long non-coding RNA (lncRNA) AK083884 in M2-Exo was found to be involved in the regulation of macrophage polarization by exosome lncRNA sequencing combined with in vitro functional assays. M2-Exo-derived AK083884 promotes macrophage M2 polarization and protects mice from CVB3-induced VM. Furthermore, we identified pyruvate kinase M2 (PKM2) as a protein target binding to AK083884 and found that PKM2 knockdown could promote macrophages to polarize to M2 phenotype. Intriguingly, functional assay revealed that downregulation of AK083884 promotes metabolic reprogramming in macrophages. In addition, co-immunoprecipitation was performed to reveal AK083884 could interact with PKM2 and inhibition of AK083884 can facilitate the binding of PKM2 and HIF-1α. Collectively, our findings uncovered an important role of M2-Exo-derived AK083884 in the regulation of macrophage polarization through metabolic reprogramming, identified a new participant in the development of VM and provided a potential clinically important therapeutic target.

Multitargeted Immunomodulatory Therapy for Viral Myocarditis by Engineered Extracellular Vesicles

Immune regulation therapies are considered promising for treating classically activated macrophage (M1)-driven viral myocarditis (VM). Alternatively, activated macrophage (M2)-derived extracellular vesicles (M2 EVs) have great immunomodulatory potential owing to their ability to reprogram macrophages, but their therapeutic efficacy is hampered by insufficient targeting capacity in vivo. Therefore, we developed cardiac-targeting peptide (CTP) and platelet membrane (PM)-engineered M2 EVs enriched with viral macrophage inflammatory protein-II (vMIP-II), termed CTP/PM-M2 EVsvMIP-II-Lamp2b, to improve the delivery of EVs "cargo" to the heart tissues. In a mouse model of VM, the intravenously injected CTP/PM-M2 EVsvMIP-II-Lamp2b could be carried into the myocardium via CTP, PM, and vMIP-II. In the inflammatory microenvironment, macrophages differentiated from circulating monocytes and macrophages residing in the heart showed enhanced endocytosis rates for CTP/PM-M2 EVsvMIP-II-Lamp2b. Subsequently, CTP/PM-M2 EVsvMIP-II-Lamp2b successfully released functional M2 EVsvMIP-II-Lamp2b into the cytosol, which facilitated the reprogramming of inflammatory M1 macrophages to reparative M2 macrophages. vMIP-II not only helps to increase the targeting ability of M2 EVs but also collaborates with M2 EVs to regulate M1 macrophages in the inflammatory microenvironment and downregulate the levels of multiple chemokine receptors. Finally, the cardiac immune microenvironment was protectively regulated to achieve cardiac repair. Taken together, our findings suggest that CTP-and-PM-engineered M2 EVsvMIP-II-Lamp2b represent an effective means for treating VM and show promise for clinical applications.

[Overexpression of lncRNA HEM2M alleviates liver injury in mice with non-alcoholic fatty liver disease]

OBJECTIVE

To explore the effects of long non-coding RNA (lncRNA) HEM2M overexpression on liver injury in mice with non-alcoholic fatty liver disease (NAFLD).

METHODS

Wild-type C57BL/6 (WT) mice and myeloid cell-specific HEM2M knock-in (MYKI) mice were fed normal (ND) or high-fat diet (HFD) for 12 weeks. After intraperitoneal glucose tolerance and insulin tolerance tests, the mice were euthanized for detection of liver function indicators in the serum and liver tissue. HE staining and F4/80 immunohistochemical staining were used to examine liver pathologies, and the levels of IL-6, IL-1β, and TNF-α in the liver tissues were determined with ELISA. The mRNA expressions of HEM2M and the markers of M1 macrophages (TNF-α, iNOS, and IL-6) and M2 macrophages (Arg-1, YM-1, and IL-10) were detected using qRT-PCR, and the protein expressions of P-AKT, T-AKT, NLRC4, caspase-1 and GSDMD were assayed using immunoblotting. Caspase-1 activity in the liver tissues was determined with colorimetric measurement and immunofluorescence assay.

RESULTS

Compared with HFD-fed WT mice, MYKI mice with HFD feeding showed milder liver function damage (P < 0.01), alleviated hepatic steatosis, and reduced liver macrophage infiltration, glucose tolerance impairment and insulin resistance (P < 0.01). The levels of IL-6, IL-1β, and TNF-α and mRNA expressions of M1 type macrophage markers were significantly decreased (P < 0.01) and those of M2 type markers increased (P < 0.01) in the liver tissues of HFD-fed MYKI mice, which also showed reduced NLRC4 inflammasome activity, caspase-1 activation, and GSDMD-N protein expression compared with their WT counterparts (P < 0.05).

CONCLUSION

Overexpression of HEM2M reduces the production of hepatic inflammatory factors, improves insulin resistance and inhibits hepatic NLRC4 inflammasome activation, which leads to reduced hepatic pyroptosis and liver injury in NAFLD mice.

Long non-coding RNAs and immune cells: Unveiling the role in viral infections

Viral infections present significant challenges to human health, underscoring the importance of understanding the immune response for effective therapeutic strategies. Immune cell activation leads to dynamic changes in gene expression. Numerous studies have demonstrated the crucial role of long noncoding RNAs (lncRNAs) in immune activation and disease processes, including viral infections. This review provides a comprehensive overview of lncRNAs expressed in immune cells, including CD8 T cells, CD4 T cells, B cells, monocytes, macrophages, dendritic cells, and granulocytes, during both acute and chronic viral infections. LncRNA-mediated gene regulation encompasses various mechanisms, including the modulation of viral replication, the establishment of latency, activation of interferon pathways and other critical signaling pathways, regulation of immune exhaustion and aging, and control of cytokine and chemokine production, as well as the modulation of interferon-stimulated genes. By highlighting specific lncRNAs in different immune cell types, this review enhances our understanding of immune responses to viral infections from a lncRNA perspective and suggests potential avenues for exploring lncRNAs as therapeutic targets against viral diseases.

LncRNA HEM2ATM improves obesity-associated adipose tissues meta-inflammation and insulin resistance by interacting with heterogeneous nuclear ribonucleoprotein U

Obesity is a complicated metabolic disease characterized by meta-inflammation in adipose tissues. In this study, we explored the roles of a new long non-coding RNA (lncRNA), HEM2ATM, which is highly expressed in adipose tissue M2 macrophages, in modulating obesity-associated meta-inflammation and insulin resistance. HEM2ATM expression decreased significantly in adipose tissue macrophages (ATMs) obtained from epididymal adipose tissues of high-fat diet (HFD)-induced obese mice. Overexpression of macrophage HEM2ATM improved meta-inflammation and insulin resistance in the adipose tissues of HFD-fed mice. Functionally, HEM2ATM negatively regulated the production of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in macrophages. Mechanistically, HEM2ATM bound to heterogeneous nuclear ribonucleoprotein U (hnRNP U), suppressed hnRNP U translocation from the nucleus to the cytoplasm, hindered the function of cytoplasmic hnRNP U on TNF-α and IL-6 mRNA stabilization, and decreased the secretion of TNF-α and IL-6. Collectively, HEM2ATM is a novel suppressor of obesity-associated meta-inflammation and insulin resistance.

Noncoding RNAs and Cardiac Fibrosis

Myocardial fibrosis is a common pathological feature of various terminal cardiovascular diseases. Progressive fibrosis is the pathological basis for the development and progression of many cardiac arrhythmias and heart failure. There are no effective reversal drugs for myocardial fibrosis due to the lack of understanding of the molecular mechanisms. Noncoding RNAs, a class of RNAs that do not function in coding proteins, have been found to be intimately involved in the life cycle of cardiomyocyte differentiation, transcription and apoptosis and are important regulators of cardiovascular disease. An increasing number of studies have shown that noncoding RNAs regulate the proliferation and transformation of cardiac fibroblasts through related signaling pathways and can be used as potential biomarkers and novel therapeutic targets for cardiac fibrosis. This article reviews the relationship between noncoding RNAs and cardiac fibrosis.

Analysis of long noncoding RNAs and messenger RNAs expression profiles in the hearts of mice with acute viral myocarditis

Acute viral myocarditis (AVMC) is a common acute myocardial inflammation caused by viral infections, which can lead to severe cardiac dysfunction. Several long noncoding RNAs (lncRNAs) with aberrant expression have been identified in the pathogenesis of AVMC. However, the expression profiles and functions of lncRNAs in AVMC have not been fully elucidated. In the present study, we constructed AVMC mouse models by intraperitoneal injection of coxsackievirus B3 (CVB3) and performed RNA sequencing (RNA-seq) on heart tissues to investigate the differences in lncRNAs and messenger RNAs (mRNAs) expression profiles. Based on the cutoff criteria of adjusted p-values (padj) <0.05 and |log2FoldChange| >1, a total of 1122 differentially expressed lncRNAs (DElncRNAs) and 3186 differentially expressed mRNAs (DEmRNAs) were screened, including 734 upregulated and 388 downregulated lncRNAs, 1821 upregulated and 1365 downregulated mRNAs. RT-qPCR analysis validated that the expression patterns of 12 randomly selected genes (6 DElncRNAs and 6 DEmRNAs) were highly consistent with those in RNA-seq, proving the reliability of the RNA-seq data. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that differentially expressed genes were mainly involved in metabolic and immune-related processes. Furthermore, co-expression networks between DElncRNAs and DEmRNAs in cytokine-cytokine receptor interaction, MAPK signaling pathway, and PI3K-Akt signaling pathway were constructed to study the molecular interactions of these molecules. Our study, for the first time, reveals the expression profiles of lncRNAs and mRNAs associated with AVMC, which may shed light on the roles of lncRNAs in disease pathogenesis and aid in discovering new therapeutic targets.

Epigenetic Regulation of Macrophage Polarization in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of hospitalization and death worldwide, especially in developing countries. The increased prevalence rate and mortality due to CVDs, despite the development of several approaches for prevention and treatment, are alarming trends in global health. Chronic inflammation and macrophage infiltration are key regulators of the initiation and progression of CVDs. Recent data suggest that epigenetic modifications, such as DNA methylation, posttranslational histone modifications, and RNA modifications, regulate cell development, DNA damage repair, apoptosis, immunity, calcium signaling, and aging in cardiomyocytes; and are involved in macrophage polarization and contribute significantly to cardiac disease development. Cardiac macrophages not only trigger damaging inflammatory responses during atherosclerotic plaque formation, myocardial injury, and heart failure but are also involved in tissue repair, remodeling, and regeneration. In this review, we summarize the key epigenetic modifications that influence macrophage polarization and contribute to the pathophysiology of CVDs, and highlight their potential for the development of advanced epigenetic therapies.

The Mechanisms of lncRNA-Mediated Multidrug Resistance and the Clinical Application Prospects of lncRNAs in Breast Cancer

Simple Summary

Multidrug resistance (MDR) is a major cause of breast cancer (BC) chemotherapy failure. Long noncoding RNAs (lncRNAs) have been shown closely related to the chemoresistance of BC. In this work, the mechanisms of lncRNA-mediated MDR in BC were elaborated from eight sections, including apoptosis, autophagy, DNA repair, cell cycle, drug efflux, epithelial-mesenchymal transition, epigenetic modification and the tumor microenvironment. Additionally, we also discuss the clinical significance of lncRNAs, which may be biomarkers for diagnosis, therapy and prognosis.

Abstract

Breast cancer (BC) is a highly heterogeneous disease and presents a great threat to female health worldwide. Chemotherapy is one of the predominant strategies for the treatment of BC; however, multidrug resistance (MDR) has seriously affected or hindered the effect of chemotherapy. Recently, a growing number of studies have indicated that lncRNAs play vital and varied roles in BC chemoresistance, including apoptosis, autophagy, DNA repair, cell cycle, drug efflux, epithelial-mesenchymal transition (EMT), epigenetic modification and the tumor microenvironment (TME). Although thousands of lncRNAs have been implicated in the chemoresistance of BC, a systematic review of their regulatory mechanisms remains to be performed. In this review, we systematically summarized the mechanisms of MDR and the functions of lncRNAs mediated in the chemoresistance of BC from the latest literature. These findings significantly enhance the current understanding of lncRNAs and suggest that they may be promising prognostic biomarkers for BC patients receiving chemotherapy, as well as therapeutic targets to prevent or reverse chemoresistance.

Long Noncoding RNAs Regulate the Inflammatory Responses of Macrophages

Long noncoding RNAs (lncRNAs) are defined as transcripts with more than 200 nucleotides that have little or no coding potential. In recent years, due to the development of next-generation sequencing (NGS), a large number of studies have revealed that lncRNAs function as key regulators to maintain immune balance and participate in diverse physiological and pathological processes in the human body. Notably, overwhelming evidence suggests that lncRNAs can regulate innate immune responses, the differentiation and development of immune cells, inflammatory autoimmune diseases, and many other immunological processes with distinct regulatory mechanisms. In this review, we summarized the emerging roles of lncRNAs in macrophage development and polarization. In addition, the potential value of lncRNAs as diagnostic biomarkers and novel therapeutic targets for the treatment of aberrant immune responses and inflammatory diseases are discussed.

Exosome membrane-modified M2 macrophages targeted nanomedicine: Treatment for allergic asthma

BACKGROUNDS

Exosomes are naturally secreted nanovesicles that have emerged as a promising therapeutic nanodelivery platform due to their specific composition, biological properties, and stability. Modifying synthetic nanoparticles with the intrinsic hallmarks of exosome membrane to create exosome mimetics could lead to safe and efficient smart silencer delivery.

OBJECTIVES

The study focuses on exploring the combination of polylactic-co-glycolic acid (PLGA)-based nanoparticles with naturally occurring exosome membrane from M2 macrophages to deliver a Dnmt3aos smart silencer to treat allergic asthma (AA) in mice.

MATERIALS AND METHODS

Exosome membrane of M2 macrophages and PLGA nanoparticles (PLGA NPs) wrapped with the smart silencer of Dnmt3aos (Dnmt3aos^{smart silencer}) were first synthesized. The resulting exosome membrane coated PLGA@Dnmt3aos^{smart silencer} (EM-PLGA@Dnmt3aos^{smart silencer}) was administered intravenously into Der f1-induced asthma mice, which was followed by the investigation of therapeutic outcomes and the mechanism in vivo.

RESULTS

Seven infusions of EM-PLGA@Dnmt3aos^{smart silencer} ameliorated AA with a marked reduction of lung inflammation. After intravenous injection, the EM-PLGA@Dnmt3aos^{smart silencer} was distributed in various organs, including the lungs, with retention over 48 h, and it targeted M2 macrophages. Moreover, the injections of EM-PLGA@Dnmt3aos^{smart silencer} markedly decreased the proportion of M2 macrophages and inflammatory cytokines in the airway. More importantly, the EM-PLGA@Dnmt3aos^{smart silencer} treatment did not obviously suppress the overall immune function of host.

CONCLUSION

To our knowledge, this study provides the first experimental evidence of the ability of EM-PLGA@Dnmt3aos^{smart silencer} to target M2 macrophages in the treatment of AA by combining exosome membrane and biomaterials, thus presenting a novel immunotherapy for the allergic disease.

The impact of non-coding RNAs on macrophage polarization

Macrophage polarization is a process through which macrophages attain unique functional features as a response to certain stimuli from their niche. Lipopolysaccharide and Th1 cytokines induce generation of M1 macrophages. On the other hand, IL-4, IL-13, IL-10, IL-33, and TGF-β induce polarization of macrophages towards M2 phenotype. This process is also modulated by a number of miRNAs and lncRNAs. miR-375, miR-let7, miR-34a, miR-155, miR-124, miR-34a, miR-511-3p, miR-99a, miR-132 and miR-145-3p are among miRNAs that regulate macrophage polarization. Meanwhile, macrophage polarization is influenced by some lncRNAs such as H19, NRON, MEG3, GAS5, RN7SK, and AK085865. Macrophage polarization has functional significance in a wide range of human disorders particularly immune disorders and cancer. In addition, the effect of certain drugs in modulation of macrophage polarization is exerted through modulation of expression of non-coding RNAs. In the current manuscript, we provide a summary of studies aimed to identification of this aspect of non-coding RNAs.

Non-coding RNAs: update on mechanisms and therapeutic targets from the ESC Working Groups of Myocardial Function and Cellular Biology of the Heart

Vast parts of mammalian genomes are actively transcribed, predominantly giving rise to non-coding RNA (ncRNA) transcripts including microRNAs, long ncRNAs, and circular RNAs among others. Contrary to previous opinions that most of these RNAs are non-functional molecules, they are now recognized as critical regulators of many physiological and pathological processes including those of the cardiovascular system. The discovery of functional ncRNAs has opened up new research avenues aiming at understanding ncRNA-related disease mechanisms as well as exploiting them as novel therapeutics in cardiovascular therapy. In this review, we give an update on the current progress in ncRNA research, particularly focusing on cardiovascular physiological and disease processes, which are under current investigation at the ESC Working Groups of Myocardial Function and Cellular Biology of the Heart. This includes a range of topics such as extracellular vesicle-mediated communication, neurohormonal regulation, inflammation, cardiac remodelling, cardio-oncology as well as cardiac development and regeneration, collectively highlighting the wide-spread involvement and importance of ncRNAs in the cardiovascular system.

Long non-coding RNA: An immune cells perspective

Long non-coding RNAs (lncRNAs) were considered as accumulated genetic waste until they were found to be gene expression regulators by highly sensitive modern genomics platforms. It is a huge class of non-coding transcripts with an arbitrary length of >200 nucleotides, which has gained much attention in the past few years. Increasing evidence from several experimental studies unraveled the expression of lncRNA linked to immune response and disease progression. However, only a small number of lncRNAs have robust evidence of their function. Differential expression of lncRNAs in different immune cells is also evident. In this review, we focused on how lncRNAs expression assist in shaping immune cells (Macrophages, Dendritic cells, NK cells, T cells, B cells, eosinophils, neutrophils, and microglial cells) function and their response to the diseased conditions. Emerging evidence revealed lncRNAs may serve as key regulators in the innate and adaptive immune response system. So, the molecular mechanism insight into the function of lncRNAs in immune response may contribute to the development of potential therapeutic targets for various disease treatments. Therefore, it is imperative to explore the expression of lncRNAs and understand its relevance associated with the immune system.

MicroRNA-30a-5p silencing polarizes macrophages toward M2 phenotype to alleviate cardiac injury following viral myocarditis by targeting SOCS1

Viral myocarditis (VMC) is a life-threatening disease characterized by severe cardiac inflammation generally caused by coxsackievirus B3 (CVB3) infection. Several microRNAs (miRNAs or miRs) are known to play crucial roles in the pathogenesis of VMC. The study aimed to decipher the role of miR-30a-5p in the underlying mechanisms of VMC pathogenesis. We first quantified miR-30a-5p expression in a CVB3-induced mouse VMC model. The physiological characteristics of mouse cardiac tissues were then detected by hematoxylin and eosin (HE) and Picrosirius red staining. We established the correlation between miR-30a-5p and SOCS1, using dual-luciferase gene assay and Pearson's correlation coefficient. The expression of inflammatory factors (IFN-γ, IL-6, IL-10, and IL-13), M1 polarization markers [TNF-α, inducible nitric oxide synthase (iNOS)], M2 polarization markers (Arg-1, IL-10), and myocardial hypertrophy markers [atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)] was detected by RT-qPCR and Western blot analysis. miR-30a-5p was found to be highly expressed in VMC mice. Silencing of miR-30a-5p improved the cardiac function index and reduced heart weight-to-body weight ratio, myocardial tissue pathological changes and fibrosis degree, serological indexes, as well as proinflammatory factor levels, while enhancing anti-inflammatory factor levels in VMC mice. Furthermore, silencing of miR-30a-5p inhibited M1 polarization of macrophages while promoting M2 polarization in vivo and in vitro. SOCS1 was a target gene of miR-30a-5p, and the aforementioned cardioprotective effects of miR-30a-5p silencing were reversed upon silencing of SOCS1. Overall, this study shows that silencing of miR-30a-5p may promote M2 polarization of macrophages and improve cardiac injury following VMC via SOCS1 upregulation, constituting a potential therapeutic target for VMC treatment.NEW & NOTEWORTHY We found in this study that microRNA (miR)-30a-5p inhibition might improve cardiac injury following viral myocarditis (VMC) by accelerating M2 polarization of macrophages via SOCS1 upregulation. Furthermore, the anti-inflammatory mechanisms of miR-30a-5p inhibition may contribute to the development of new therapeutic strategies for VMC.

The Role of Non-coding RNAs in Viral Myocarditis

Viral myocarditis (VMC) is a disease characterized as myocardial parenchyma or interstitium inflammation caused by virus infection, especially Coxsackievirus B3 (CVB3) infection, which has no accurate non-invasive examination for diagnosis and specific drugs for treatment. The mechanism of CVB3-induced VMC may be related to direct myocardial damage of virus infection and extensive damage of abnormal immune response after infection. Non-coding RNA (ncRNA) refers to RNA that is not translated into protein and plays a vital role in many biological processes. There is expanding evidence to reveal that ncRNAs regulate the occurrence and development of VMC, which may provide new treatment or diagnosis targets. In this review, we mainly demonstrate an overview of the potential role of ncRNAs in the pathogenesis, diagnosis and treatment of CVB3-induced VMC.

lncRNA AK085865 Promotes Macrophage M2 Polarization in CVB3-Induced VM by Regulating ILF2-ILF3 Complex-Mediated miRNA-192 Biogenesis

Accumulating evidence indicates that macrophage polarization plays a crucial role in coxsackievirus B3 (CVB3)-induced viral myocarditis (VM). Our previous study demonstrated that long noncoding ribonucleic acid (lncRNA) AK085865 ablation confers susceptibility to VM by regulating macrophage polarization. However, the detailed molecular mechanisms by which AK085865 regulates macrophage polarization remain to be explored. In this study, we found that AK085865 specifically interacts with interleukin enhancer-binding factor 2 (ILF2) and facilitates M2 macrophage polarization by functioning as a negative regulator in the ILF2-ILF3 complex-mediated microRNA (miRNA or miR) processing pathway. miR-192 was downregulated, whereas the levels of pri-miR-192 were significantly increased in bone marrow-derived macrophages (BMDMs) from AK085865^-/- mice compared with the BMDMs from wild-type (WT) mice. Conversely, knockdown of ILF2 resulted in elevated levels of mature miR-192 and decreased expression of pri-miR-192 in BMDMs from AK085865^-/- mice. Moreover, miR-192 overexpression promoted macrophage M2 polarization in vitro, and interleukin-1 receptor-associated kinase 1 (IRAK1) was identified as a direct target. miR-192 overexpression effectively rescued mice from lethal myocarditis caused by CVB3 infection and switched myocardial-infiltrating macrophages to a predominant M2 phenotype. Collectively, our findings uncover a critical mechanism of AK085865 in the regulation of macrophage polarization in vitro and in vivo and provide a potential, clinically significant therapeutic target.

Long non-coding RNA AK085865 ablation confers susceptibility to viral myocarditis by regulating macrophage polarization

Accumulating evidence indicates that regulators of macrophage polarization may exert pivotal functions in the development of coxsackievirus B3 (CVB3)-induced viral myocarditis (VM). However, the mechanisms underlying macrophage polarization remain to be explored. Here, we sought to identify novel and functionally important long non-coding RNAs (lncRNAs) during macrophage polarization and to investigate their function and contribution to VM. In this study, we identified the lncRNA AK085865 as an important regulator of macrophage polarization. Knock-down of AK085865 diminished phenotypical expression of M2 macrophages while promoting polarization to the M1 phenotype. Moreover, AK085865^-/- mice had increased susceptibility to CVB3-induced VM. We observed striking bias towards M1 macrophages, whereas the M2 population was decreased in AK085865^-/- VM mice. Collectively, our findings uncover a critical role of AK085865 in the regulation of macrophage polarization in vitro and in vivo, identifying a new player in the development of VM and providing a potential clinically significant therapeutic target.