Challenging and target-based shifting strategies for heart failure treatment: An update from the last decades.

Heart failure (HF) is a major global health problem afflicting millions worldwide. Despite the significant advances in therapies and prevention, HF still carries very high morbidity and mortality, requiring enormous healthcare-related expenditure, and the search for new weapons goes on. Following initial treatment strategies targeting inotropism and congestion, attention has focused on offsetting the neurohormonal overactivation and three main therapies, including angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor antagonists, ß-adrenoceptor antagonists, and mineralocorticoid receptor antagonists, have been the foundation of standard treatment for patients with HF. Recently, a paradigm shift, including angiotensin receptor-neprilysin inhibitor, sodium glucose co-transporter 2 inhibitor, and ivabradine, has been added. Moreover, soluble guanylate cyclase stimulator, elamipretide, and omecamtiv mecarbil have come out as a next-generation therapeutic agent for patients with HF. Although these pharmacologic therapies have been significantly successful in relieving symptoms, there is still no complete cure for HF. We may be currently entering a new era of treatment for HF with animal experiments and human clinical trials assessing the value of antibody-based immunotherapy and gene therapy as a novel therapeutic strategy. Such tempting therapies still have some challenges to be addressed but may become a weighty option for treatment of HF. This review article will compile the paradigm shifts in HF treatment over the past dozen years or so and illustrate current landscape of antibody-based immunotherapy and gene therapy as a new therapeutic algorithm for patients with HF.

Bioinformatic Identification of Potential RNA Alterations on the Atrial Fibrillation Remodeling from Human Pulmonary Veins.

Atrial fibrillation (AF) is the most frequent persistent arrhythmia. Many genes have been reported as a genetic background for AF. However, most transcriptome analyses of AF are limited to the atrial samples and have not been evaluated by multiple cardiac regions. In this study, we analyzed the expression levels of protein-coding and long noncoding RNAs (lncRNAs) in six cardiac regions by RNA-seq. Samples were donated from six subjects with or without persistent AF for left atria, left atrial appendages, right atria, sinoatrial nodes, left ventricles, right ventricles, and pulmonary veins (PVs), and additional four right atrial appendages samples were collected from patients undergoing mitral valve replacement. In total, 23 AF samples were compared to 23 non-AF samples. Surprisingly, the most influenced heart region in gene expression by AF was the PV, not the atria. The ion channel-related gene set was significantly enriched upon analysis of these significant genes. In addition, some significant genes are cancer-related lncRNAs in PV in AF. A co-expression network analysis could detect the functional gene clusters. In particular, the cancer-related lncRNA, such as SAMMSON and FOXCUT, belong to the gene network with the cancer-related transcription factor FOXC1. Thus, they may also play an aggravating role in the pathogenesis of AF, similar to carcinogenesis. In the least, this study suggests that (1) RNA alteration is most intense in PVs and (2) post-transcriptional gene regulation by lncRNA may contribute to the progression of AF. Through the screening analysis across the six cardiac regions, the possibility that the PV region can play a role other than paroxysmal triggering in the pathogenesis of AF was demonstrated for the first time. Future research with an increase in the number of PV samples will lead to a novel understanding of the pathophysiology of AF.

Structural Variants of Midnolin, a Genetic Risk Factor for Parkinson's Disease, in a Yamagata Cohort.

Parkinson's disease (PD) is a common neurodegenerative disease. We previously identified Midnolin (MIDN) to be a genetic risk factor for PD in both Yamagata (Japan) and British populations. However, the scale of our previous study was not sufficient to identify MIDN structural variants in the ascertained control of Yamagata Prefecture. We, therefore, reanalyzed MIDN variants in 3021 individuals from Yamagata Prefecture to compare with that in our previous British cohort study. MIDN copy number loss was only found in two cases (0.0662%), which was a lower frequency than that (1.64%) of the previously studied British cohort. Between the Yamagata and British groups, there was significant difference for rs3746106, located in the 5'-UTR of MIDN mRNA (p = 0.0003344, odds ratio 1.143), and for rs3746107, which corresponds to Ala34 (p < 2.2 × 10-16, odds ratio 5.89401). This study indicates that MIDN loss is relatively rare in the general Japanese population. Considering our previous studies that the frequency of MIDN loss is high among patients with PD (10.5 and 6.55% in Yamagata and Britain, respectively), the MIDN variants are much higher genetic risk factors for PD in a Japanese population than in a British population.

The large part German medicine has played in the development of experimental pharmacology in Japan.

The history of hitherto existing pharmacology in Japan presented here is authored in commemoration of the 150th anniversary of Naunyn-Schmiedeberg's Archives of Pharmacology. After the publication of the new book of anatomy "Anatomische Tabellen" translated into Japanese in 1774, the foundation of understanding the medical science was gradually formed in Japan under seclusion policy, and, since the Meiji Restoration of 1868, the modernization of Japanese medicine was rapidly fostered on the basis of German medicine. Thus, the Japanese government officially adopted German medicine, and the philosophy and practice of German medical schools were incorporated. Most of the medical texts used in Japan were of German origins, often in Dutch translations, and many Japanese physicians and medical researchers studied abroad in Germany. The start of experimental pharmacology in Japan was also made up by Japanese disciples of Oswald Schmiedeberg, who was the one of founders of the Archives in 1873. Additionally, it was customary for professor candidates in charge of pharmacology in medical faculties in Japan to go to Germany and study pharmacology. Through such historical circumstances, the Japanese Pharmacology Society has been established to fulfill the responsibility for contributing internationally to world-class research achievements in the field of medical sciences by supplying numerous talented pharmacologists. During the course of the development of experimental pharmacology in Japan, the Archives has provided an excellent stage for many Japanese pharmacologists to publish their research outcomes to proliferate them internationally. Without German medicine influence, Japanese pharmacology would not have been what it is today.

Identifying the core concepts of pharmacology education: A global initiative.

BACKGROUND AND PURPOSE: In recent decades, a focus on the most critical and fundamental concepts has proven highly advantageous to students and educators in many science disciplines. Pharmacology, unlike microbiology, biochemistry, or physiology, lacks a consensus list of such core concepts. EXPERIMENTAL APPROACH: We sought to develop a research-based, globally relevant list of core concepts that all students completing a foundational pharmacology course should master. This two-part project consisted of exploratory and refinement phases. The exploratory phase involved empirical data mining of the introductory sections of five key textbooks, in parallel with an online survey of over 200 pharmacology educators from 17 countries across six continents. The refinement phase involved three Delphi rounds involving 24 experts from 15 countries across six continents. KEY RESULTS: The exploratory phase resulted in a consolidated list of 74 candidate core concepts. In the refinement phase, the expert group produced a consensus list of 25 core concepts of pharmacology. CONCLUSION AND IMPLICATIONS: This list will allow pharmacology educators everywhere to focus their efforts on the conceptual knowledge perceived to matter most by experts within the discipline. Next steps for this project include defining and unpacking each core concept and developing resources to help pharmacology educators globally teach and assess these concepts within their educational contexts.

Comparative Study of Transcriptome in the Hearts Isolated from Mice, Rats, and Humans.

The heart is a significant organ in mammalian life, and the heartbeat mechanism has been an essential focus of science. However, few studies have focused on species differences. Accordingly, challenges remain in studying genes that have universal functions across species and genes that determine species differences. Here, we analyzed transcriptome data in mouse, rat, and human atria, ventricles, and sinoatrial nodes (SA) obtained from different platforms and compared them by calculating specificity measure (SPM) values in consideration of species differences. Among the three heart regions, the species differences in SA were the greatest, and we searched for genes that determined the essential characteristics of SA, which was SHOX2 in our criteria. The SPM value of SHOX2 was prominently high across species. Similarly, by calculating SPM values, we identified 3 atrial-specific, 11 ventricular-specific, and 17 SA-specific markers. Ontology analysis identified 70 cardiac region- and species-specific ontologies. These results suggest that reanalyzing existing data by calculating SPM values may identify novel tissue-specific genes and species-dependent gene expression. This study identified the importance of SHOX2 as an SA-specific transcription factor, a novel cardiac regional marker, and species-dependent ontologies.

Preferential Expression of Ca2+-Stimulable Adenylyl Cyclase III in the Supraventricular Area, including Arrhythmogenic Pulmonary Vein of the Rat Heart.

Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na+-Ca2+ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on adenylyl cyclase (AC) as another effector of norepinephrine stimulation. RT-PCR, immunohistochemistry, and Western blotting revealed that the abundant expression of Ca2+-stimulable AC3 was restricted to the supraventricular area, including the PVs. All the other AC isotypes hardly displayed any region-specific expressions. Immunostaining of isolated cardiomyocytes showed an enriched expression of AC3 along the t-tubules in PV myocytes. The cAMP-dependent response of L-type Ca2+ currents in the PV and LA cells is strengthened by the 0.1 mM intracellular Ca2+ condition, unlike in the ventricular cells. The norepinephrine-induced automaticity of PV cardiomyocytes was reversibly suppressed by 100 µM SQ22536, an adenine-like AC inhibitor. These findings suggest that the specific expression of AC3 along t-tubules may contribute to arrhythmogenic automaticity in rat PV cardiomyocytes.

Insulin Enhances Gene Expression of Midnolin, a Novel Genetic Risk Factor for Parkinson's Disease, via Extracellular Signal-Regulated Kinase, Phosphoinositide 3-Kinase and Multiple Transcription Factors in SH-SY5Y Cells.

Parkinson's disease (PD) is the second most common neurodegenerative disease. Although many monogenic variants have been identified that cause familial PD, most cases are sporadic and the mechanisms of sporadic PD onset remain unclear. We previously identified midnolin (MIDN) as a novel genetic risk factor for PD in a Japanese population. MIDN copy number loss was strongly associated with sporadic PD, which was replicated in a British population. Furthermore, suppression of MIDN expression in rat pheochromocytoma cells inhibits neurite outgrowth and expression of Parkin ubiquitin ligase. However, the detailed molecular mechanisms of MIDN expression are unknown. We, therefore, investigated the molecular mechanism of MIDN expression in human neuroblastoma SH-SY5Y cells. We found that MIDN expression was promoted by insulin via extracellular-signal regulated kinase1/2 and phosphoinositide 3-kinase-dependent pathways. In addition, MIDN promoter activity was enhanced by mutations at transcription factor AP-2 consensus sequences and reduced by mutations at cAMP response element-binding protein and activator protein 1 (AP-1) consensus sequences. The dominant-negative cAMP response element-binding protein mutant did not block MIDN promoter activity, but both the pharmacological inhibitor and decoy oligodeoxynucleotide for AP-1 significantly blocked its activity. Additionally, DNA binding of c-FOS and c-JUN to the AP-1 consensus sequence in the MIDN promoter was enhanced by insulin as determined by chromatin immunoprecipitation, which suggested that AP-1 positively regulated MIDN expression. Taken together, this study reveals molecular mechanisms of MIDN gene expression induced by insulin in neuronal cells, and drugs which promote MIDN expression may have potential to be a novel medicine for PD. SIGNIFICANCE STATEMENT: We demonstrated that insulin promotes midnolin expression via extracellular-signal regulated kinase 1/2 and phosphoinositide 3-kinase pathways. Furthermore, we identified the important region of the MIDN promoter and showed that transcription factors, including activator protein 1, positively regulate MIDN expression, whereas transcription factor AP-2 negatively regulates basal and insulin-induced MIDN expression. We believe that our observations are important and that they contribute to the development of novel drugs to treat Parkinson's disease.

ALOX12 mutation in a family with dominantly inherited bleeding diathesis.

The arachidonic acid (AA) cascade plays a significant role in platelet aggregation. AA released from membrane phospholipids is metabolized by cyclooxygenase (COX) pathway to thromboxane A2 (TXA2) or by 12S-lipoxygenase (ALOX12) to 12-hydroperoxyeicosatetraenoic acid (12-HPETE). In contrast to a well-known role of the COX pathway in platelet aggregation, the role of ALOX12 is not well understood. Platelets of ALOX12-deficient mice exhibit increased sensitivity for ADP-induced aggregation. However, recent evidence strongly suggests a significant role of ALOX12 in platelet aggregation and calcium signaling. 12-HPETE potentiates thrombin- and thromboxane-induced platelet aggregation, and calcium signaling. Inhibition experiments of ALOX12 demonstrated decreased platelet aggregation and calcium signaling in stimulated platelets. We studied a family with a dominantly inherited bleeding diathesis using next-generation sequencing analysis. Platelet aggregation studies revealed that the proband's platelets had defective aggregation responses to ADP, TXA2 mimetic U46619, collagen, and AA, normal affinity of TXA2 receptor for U46619, and normal induction of GTPase activity upon stimulation with U46619. However, the production of inositol 1,4,5-triphosphate (IP3) was only increased up to 30% of the control upon U46619 stimulation, suggesting a defect in phospholipase C-ß2 (PLCB2) activation downstream from TXA2 receptors. Affected family members had no mutation of PLCB2, but had a heterozygous c.1946A > G (p.Tyr649Cys) mutation of ALOX12. ALOX12 activity in platelets from the affected members was decreased to 25-35% of the control. Our data strongly suggested that a heterozygous c.1946A > G ALOX12 mutation was a disease-causing mutation; however, further experiments are required to confirm the pathogenesis of ALOX12 mutation in platelet aggregation.

Azelnidipine treatment reduces the expression of Cav1.2 protein.

AIMS: Azelnidipine, a third-generation dihydropyridine calcium channel blocker (DHP CCB), has a characteristic hypotensive effect that persists even after it has disappeared from the plasma, which is thought to be due to its high hydrophobicity. However, because azelnidipine is unique, it might have other unknown effects on L-type Cav1.2 channels that result in the long-lasting decrease of blood pressure. The aim of this study was to investigate the potential quantitative modification of Cav1.2 by azelnidipine. MAIN METHODS: HEK293 cells were used to express Cav1.2 channels. Immunocytochemical analysis was performed to detect changes in the surface expression of the pore-forming subunit of the Cav1.2 channel, Cav1.2α1c. Western blotting analysis was performed to evaluate changes in expression levels of total Cav1.2α1c and Cavß2c. KEY FINDINGS: The surface expression of Cav1.2α1c was markedly reduced by treatment with azelnidipine, but not with other DHP CCBs (amlodipine and nicardipine). Results obtained with a dynamin inhibitor and an early endosome marker suggested that the reduction of surface Cav1.2α1c was not likely caused by internalization. Azelnidipine reduced the total amount of Cav1.2α1c protein in HEK293 cells and rat pulmonary artery smooth muscle cells. The reduction of Cav1.2α1c was rescued by inhibiting proteasome activity. In contrast, azelnidipine did not affect the amount of auxiliary Cavß2c subunits that function as a chaperone of Cav1.2. SIGNIFICANCE: This study is the first to demonstrate that azelnidipine reduces the expression of Cav1.2α1c, which might partly explain its long-lasting hypotensive effect.

Midnolin is a confirmed genetic risk factor for Parkinson's disease.

OBJECTIVE: Genetic analysis of patients with familial Parkinson's disease (PD) identified many causative genes. However, the majority of PD cases are sporadic, and the mechanisms of onset still remain unclear. Previously, we found that Midnolin (MIDN) is associated with PD in a Yamagata (Japan) cohort study and that MIDN regulates neurite outgrowth and Parkin expression in neuronal cells. In the present study, we aimed to replicate the genetic association between MIDN and PD in a large British population cohort. METHODS: In this replication study, we analyzed the copy number variations and single-nucleotide polymorphisms of the MIDN gene in a large British population on a case-control genome-wide association study dataset including 2,860 controls and 2,168 PD patients. RESULTS: There was significant copy number loss in the MIDN gene with an odds ratio of 4.35 (P < 2.2 × 10-16 ). Furthermore, there were many patients in both the British and Yamagata case groups who have a long spanning deletion. The odds ratio dramatically increased to 22.3 (P = 3.59 × 10-15 ) when a deletion spanning more than 50,000 bp was defined as the copy number loss. There were no significant differences between the controls and study cases for two relatively frequent single-nucleotide polymorphisms (rs3746106 and rs3746107). INTERPRETATION: We showed the strong genetic association of MIDN with PD development in a British population and in a Japanese population, suggesting MIDN is a confirmed and universal genetic risk factor for PD.

Molecular identification of HSPA8 as an accessory protein of a hyperpolarization-activated chloride channel from rat pulmonary vein cardiomyocytes.

Pulmonary veins (PVs) are the major origin of atrial fibrillation. Recently, we recorded hyperpolarization-activated Cl- current (ICl, h) in rat PV cardiomyocytes. Unlike the well-known chloride channel protein 2 (CLCN2) current, the activation curve of ICl, h was hyperpolarized as the Cl- ion concentration ([Cl-] i ) increased. This current could account for spontaneous activity in PV cardiomyocytes linked to atrial fibrillation. In this study, we aimed to identify the channel underlying ICl, h Using RT-PCR amplification specific for Clcn2 or its homologs, a chloride channel was cloned from rat PV and detected in rat PV cardiomyocytes using immunocytochemistry. The gene sequence and electrophysiological functions of the protein were identical to those previously reported for Clcn2, with protein activity observed as a hyperpolarization-activated current by the patch-clamp method. However, the [Cl-] i dependence of activation was entirely different from the observed ICl, h of PV cardiomyocytes; the activation curve of the Clcn2-transfected cells shifted toward positive potential with increased [Cl-] i , whereas the ICl, h of PV and left ventricular cardiomyocytes showed a leftward shift. Therefore, we used MS to explore the possibility of additional proteins interacting with CLCN2 and identified an individual 71-kDa protein, HSPA8, that was strongly expressed in rat PV cardiomyocytes. With co-expression of HSPA8 in HEK293 and PC12 cells, the CLCN2 current showed voltage-dependent activation and shifted to negative potential with increasing [Cl-] i Molecular docking simulations further support an interaction between CLCN2 and HSPA8. These findings suggest that CLCN2 in rat heart contains HSPA8 as a unique accessory protein.

KCNQ1 is internalized by activation of α1 adrenergic receptors.

KCNQ1 (Kv7.1 or KvLQT1) plays important physiological roles in various tissues forming potassium channels with KCNE subunits. Among the channels formed by KCNQ1 and KCNE subunits, the best studied is the slow delayed rectifier potassium channel in the heart, the IKs (KCNQ1/KCNE1) channel, which is critical for repolarization of cardiac action potential. The KCNQ1 channel is internalized by Nedd4/Nedd4-like ligase-dependent ubiquitination. It is also reported that phosphorylation of KCNE1 by PKC results in internalization of the KCNQ1/KCNE1 channel. Because we have observed down-regulation of KCNQ1/KCNE1 currents by activation of the α1-adrenergic receptor (α1AR) that activates PKC, this study investigated whether α1AR causes internalization of the KCNQ1 protein. We fused HaloTag to the extracellular region of KCNQ1 (Halo-KCNQ1) and co-expressed it with α1ARs in HEK293 cells. The KCNQ1 protein on the cell surface was selectively labeled with membrane-impermeable HaloTag ligands, and changes in its localization were monitored by confocal fluorescence microscopy. Activation of α1AAR and α1BAR caused marked internalization of KCNQ1, which was not KCNE1-dependent. Internalization of KCNQ1 by α1AR activation was inhibited by disruption of the PY motif or the YXXΦ motif in the C-terminus. Double staining for the receptor and the channel revealed that KCNQ1 internalization was independent of α1AR internalization. Our results suggest that α1AR-mediated direct internalization of KCNQ1 is AP2/clathrin-dependent and may be triggered by ubiquitination of KCNQ1 via the AMP dependent kinase (AMPK)/Nedd4-2 pathway. When phenylephrine was applied to rat neonatal cardiomyocytes transfected with KCNQ1 and α1AR, the KCNQ1 protein was internalized. The internalization of KCNQ1 by α1AR would affect pathophysiology in a variety of tissues expressing KCNQ1, which merits further in vivo study.

ERK5 Phosphorylates Kv4.2 and Inhibits Inactivation of the A-Type Current in PC12 Cells.

Extracellular signal-regulated kinase 5 (ERK5) regulates diverse physiological responses such as proliferation, differentiation, and gene expression. Previously, we demonstrated that ERK5 is essential for neurite outgrowth and catecholamine biosynthesis in PC12 cells and sympathetic neurons. However, it remains unclear how ERK5 regulates the activity of ion channels, which are important for membrane excitability. Thus, we examined the effect of ERK5 on the ion channel activity in the PC12 cells that overexpress both ERK5 and the constitutively active MEK5 mutant. The gene and protein expression levels of voltage-dependent Ca2+ and K⁺ channels were determined by RT-qPCR or Western blotting. The A-type K⁺ current was recorded using the whole-cell patch clamp method. In these ERK5-activated cells, the gene expression levels of voltage-dependent L- and P/Q-type Ca2+ channels did not alter, but the N-type Ca2+ channel was slightly reduced. In contrast, those of Kv4.2 and Kv4.3, which are components of the A-type current, were significantly enhanced. Unexpectedly, the protein levels of Kv4.2 were not elevated by ERK5 activation, but the phosphorylation levels were increased by ERK5 activation. By electrophysiological analysis, the inactivation time constant of the A-type current was prolonged by ERK5 activation, without changes in the peak current. Taken together, ERK5 inhibits an inactivation of the A-type current by phosphorylation of Kv4.2, which may contribute to the neuronal differentiation process.

Transcriptome Analysis Reveals That Midnolin Regulates mRNA Expression Levels of Multiple Parkinson's Disease Causative Genes.

We recently found that 10.5% of sporadic Parkinson's disease (PD) patients lacked one copy of the midnolin (MIDN) gene. In addition, gene knock-down/out of MIDN caused down-regulation of parkin E3 ubiquitin ligase, indicating MIDN to be a novel PD-risk factor or causative gene. In this study, we performed RNA-sequencing and transcriptome analysis of Midn wild-type and knockout cells. Midn positively or negatively regulated the expression of a wide variety of genes, including causative familial PD genes, such as α-synuclein, parkin, and EIF4G1. However, EIF4G1 protein levels were not altered by the reduction of its mRNA by Midn loss, as seen that parkin protein levels were correlated to the mRNA down-regulation. Taken together, these findings indicate that MIDN regulates the expression of a wide variety of genes, including multiple PD-causative genes and is associated with PD onset.

Insulin treatment augments KCNQ1/KCNE1 currents but not KCNQ1 currents, which is associated with an increase in KCNE1 expression.

Diabetes mellitus affects ion channel physiology. We have previously reported that acute application of insulin suppresses the KCNQ1/KCNE1 currents that play an important role in terminating ventricular action potential. In this study, we investigated the effect of long-term insulin treatment on KCNQ1/KCNE1 currents using the Xenopus oocyte expression system. Insulin treatment with a duration longer than 6 h had an opposite effect to acute insulin application, that is, it augmented the KCNQ1/KCNE1 currents. Inhibitors of PI3K, wortmannin and LY294002, and a MEK inhibitor, U0126, abolished the potentiating effect of long-term insulin treatment. The long-term treatment with insulin had no effect on KCNQ1 currents indicating an essential role of KCNE1 in the insulin effect, which is similar to the acute insulin effect. Cycloheximide, an inhibitor of protein synthesis, and brefeldin A, an inhibitor of protein transport from endoplasmic reticulum, suppressed the long-term insulin effect. Western blotting analysis combined with these pharmacological data suggest that long-term insulin treatment augments KCNQ1/KCNE1 currents by increasing KCNE1 protein expression.

Midnolin is a novel regulator of parkin expression and is associated with Parkinson's Disease.

Midnolin (MIDN) was first discovered in embryonic stem cells, but its physiological and pathological roles are, to date, poorly understood. In the present study, we therefore examined the role of MIDN in detail. We found that in PC12 cells, a model of neuronal cells, MIDN localized primarily to the nucleus and intracellular membranes. Nerve growth factor promoted MIDN gene expression, which was attenuated by specific inhibitors of extracellular signal-regulated kinases 1/2 and 5. MIDN-deficient PC12 cells created using CRISPR/Cas9 technology displayed significantly impaired neurite outgrowth. Interestingly, a genetic approach revealed that 10.5% of patients with sporadic Parkinson's disease (PD) had a lower MIDN gene copy number whereas no copy number variation was observed in healthy people, suggesting that MIDN is involved in PD pathogenesis. Furthermore, the expression of parkin, a major causative gene in PD, was significantly reduced by CRISPR/Cas9 knockout and siRNA knockdown of MIDN. Activating transcription factor 4 (ATF4) was also down-regulated, which binds to the cAMP response element (CRE) in the parkin core promoter region. The activity of CRE was reduced following MIDN loss. Overall, our data suggests that MIDN promotes the expression of parkin E3 ubiquitin ligase, and that MIDN loss can trigger PD-related pathogenic mechanisms.