Isoquercitrin from Apocynum venetum L. Exerts Antiaging Effects on Yeasts via Stress Resistance Improvement and Mitophagy Induction through the Sch9/Rim15/Msn Signaling Pathway.

BACKGROUND: With the development of an aging sociality, aging-related diseases, such as Alzheimer's disease, cardiovascular disease, and diabetes, are dramatically increasing. To find small molecules from natural products that can prevent the aging of human beings and the occurrence of these diseases, we used the lifespan assay of yeast as a bioassay system to screen an antiaging substance. Isoquercitrin (IQ), an antiaging substance, was isolated from Apocynum venetum L., an herbal tea commonly consumed in Xinjiang, China. AIM OF THE STUDY: In the present study, we utilized molecular-biology technology to clarify the mechanism of action of IQ. METHODS: The replicative lifespans of K6001 yeasts and the chronological lifespans of YOM36 yeasts were used to screen and confirm the antiaging effect of IQ. Furthermore, the reactive oxygen species (ROS) and malondialdehyde (MDA) assay, the survival assay of yeast under stresses, real-time polymerase chain reaction (RT-PCR) and Western blotting analyses, the replicative-lifespan assay of mutants, such as Δsod1, Δsod2, Δgpx, Δcat, Δskn7, Δuth1, Δatg32, Δatg2, and Δrim15 of K6001, autophagy flux analysis, and a lifespan assay of K6001 yeast after giving a mitophagy inhibitor and activator were performed. RESULTS: IQ extended the replicative lifespans of the K6001 yeasts and the chronological lifespans of the YOM36 yeasts. Furthermore, the reactive nitrogen species (RNS) showed no change during the growth phase but significantly decreased in the stationary phase after treatment with IQ. The survival rates of the yeasts under oxidative- and thermal-stress conditions improved upon IQ treatment, and thermal stress was alleviated by the increasing superoxide dismutase (Sod) activity. Additionally, IQ decreased the ROS and MDA of the yeast while increasing the activity of antioxidant enzymes. However, it could not prolong the replicative lifespans of Δsod1, Δsod2, Δgpx, Δcat, Δskn7, and Δuth1 of K6001. IQ significantly increased autophagy and mitophagy induction, the presence of free green fluorescent protein (GFP) in the cytoplasm, and ubiquitination in the mitochondria of the YOM38 yeasts at the protein level. IQ did not prolong the replicative lifespans of Δatg2 and Δatg32 of K6001. Moreover, IQ treatment led to a decrease in Sch9 at the protein level and an increase in the nuclear translocation of Rim15 and Msn2. CONCLUSIONS: These results indicated that the Sch9/Rim15/Msn signaling pathway, as well as antioxidative stress, anti-thermal stress, and autophagy, were involved in the antiaging effects of IQ in the yeasts.

Yeast Tor complex 1 phosphorylates eIF4E-binding protein, Caf20.

Tor complex 1 (TORC1), a master regulator of cell growth, is an evolutionarily conserved protein kinase within eukaryotic organisms. To control cell growth, TORC1 governs translational processes by phosphorylating its substrate proteins in response to cellular nutritional cues. Mammalian TORC1 (mTORC1) assumes the responsibility of phosphorylating the eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) to regulate its interaction with eIF4E. The budding yeast Saccharomyces cerevisiae possesses a pair of 4E-BP genes, CAF20 and EAP1. However, the extent to which the TORC1-4E-BP axis regulates translational initiation in yeast remains uncertain. In this study, we demonstrated the influence of TORC1 on the phosphorylation status of Caf20 in vivo, as well as the direct phosphorylation of Caf20 by TORC1 in vitro. Furthermore, we found the TORC1-dependent recruitment of Caf20 to the 80S ribosome. Consequently, our study proposes a plausible involvement of yeast's 4E-BP in the efficacy of translation initiation, an aspect under the control of TORC1.

Alpha 2-macroglobulin acts as a clearance factor in the lysosomal degradation of extracellular misfolded proteins.

Proteostasis regulates protein folding and degradation; its maintenance is essential for resistance to stress and aging. The loss of proteostasis is associated with many age-related diseases. Within the cell, molecular chaperones facilitate the refolding of misfolded proteins into their bioactive forms, thus preventing undesirable interactions and aggregation. Although the mechanisms of intracellular protein degradation pathways for intracellular misfolded proteins have been extensively studied, the protein degradation pathway for extracellular proteins remain poorly understood. In this study, we identified several misfolded proteins that are substrates for alpha 2-macroglobulin (α2M), an extracellular chaperone. We also established a lysosomal internalization assay for α2M, which revealed that α2M mediates the lysosomal degradation of extracellular misfolded proteins. Comparative analyses of α2M and clusterin, another extracellular chaperone, indicated that α2M preferentially targets aggregation-prone proteins. Thus, we present the degradation pathway of α2M, which interacts with aggregation-prone proteins for lysosomal degradation via selective internalization.

CCPG1 recognizes endoplasmic reticulum luminal proteins for selective ER-phagy.

The endoplasmic reticulum (ER) is a major cell compartment where protein synthesis, folding, and posttranslational modifications occur with assistance from a wide variety of chaperones and enzymes. Quality control systems selectively eliminate abnormal proteins that accumulate inside the ER due to cellular stresses. ER-phagy, that is, selective autophagy of the ER, is a mechanism that maintains or reestablishes cellular and ER-specific homeostasis through removal of abnormal proteins. However, how ER luminal proteins are recognized by the ER-phagy machinery remains unclear. Here, we applied the aggregation-prone protein, six-repeated islet amyloid polypeptide (6xIAPP), as a model ER-phagy substrate and found that cell cycle progression 1 (CCPG1), which is an ER-phagy receptor, efficiently mediates its degradation via ER-phagy. We also identified prolyl 3-hydroxylase family member 4 (P3H4) as an endogenous cargo of CCPG1-dependent ER-phagy. The ER luminal region of CCPG1 contains several highly conserved regions that we refer to as cargo-interacting regions (CIRs); these interact directly with specific luminal cargos for ER-phagy. Notably, 6xIAPP and P3H4 interact directly with different CIRs. These findings indicate that CCPG1 is a bispecific ER-phagy receptor for ER luminal proteins and the autophagosomal membrane that contributes to the efficient removal of aberrant ER-resident proteins through ER-phagy.

Artificial control of mating type and repeated mating to produce polyploid cells in Saccharomyces cerevisiae.

The budding yeast Saccharomyces cerevisiae is an excellent model for examining the effects of ploidy. Here, we provide a protocol for producing polyploid cells by creating a basic unit (matΔ) and polyploidizing it via repeated mating. We describe steps for basic unit construction by one-step transformation, increased ploidy via repeated mating, and ploidy confirmation using flow cytometry. This protocol can be broadly applied to evaluate the physiology of polyploid cells. For complete details on the use and execution of this protocol, please refer to Oya and Matsuura (2022).1.

Serine metabolism contributes to cell survival by regulating extracellular pH and providing an energy source in Saccharomyces cerevisiae.

Changes in extracellular pH affect the homeostasis and survival of unicellular organisms. Supplementation of culture media with amino acids can extend the lifespan of budding yeast, Saccharomyces cerevisiae, by alleviating the decrease in pH. However, the optimal amino acids to use to achieve this end, and the underlying mechanisms involved, remain unclear. Here, we describe the specific role of serine metabolism in the regulation of pH in a medium. The addition of serine to synthetic minimal medium suppressed acidification, and at higher doses increased the pH. CHA1, which encodes a catabolic serine hydratase that degrades serine into ammonium and pyruvate, is essential for serine-mediated alleviation of acidification. Moreover, serine metabolism supports extra growth after glucose depletion. Therefore, medium supplementation with serine can play a prominent role in the batch culture of budding yeast, controlling extracellular pH through catabolism into ammonium and acting as an energy source after glucose exhaustion.

Gentirigeoside B from Gentiana rigescens Franch Prolongs Yeast Lifespan via Inhibition of TORC1/Sch9/Rim15/Msn Signaling Pathway and Modification of Oxidative Stress and Autophagy.

Gentirigeoside B (GTS B) is a dammaren-type triterpenoid glycoside isolated from G. rigescens Franch, a traditional Chinese medicinal plant. In the present study, the evaluation of the anti-aging effect and action mechanism analysis for this compound were conducted. GTS B significantly extended the replicative lifespan and chronological lifespan of yeast at doses of 1, 3 and 10 µM. Furthermore, the inhibition of Sch9 and activity increase of Rim15, Msn2 proteins which located downstream of TORC1 signaling pathway were observed after treatment with GTS B. Additionally, autophagy of yeast was increased. In addition, GTS B significantly improved survival rate of yeast under oxidative stress conditions as well as reduced the levels of ROS and MDA. It also increased the gene expression and enzymatic activities of key anti-oxidative enzymes such as Sod1, Sod2, Cat and Gpx. However, this molecule failed to extend the lifespan of yeast mutants such as ∆cat, ∆gpx, ∆sod1, ∆sod2, ∆skn7 and ∆uth1. These results suggested that GTS B exerts an anti-aging effect via inhibition of the TORC1/Sch9/Rim15/Msn signaling pathway and enhancement of autophagy. Therefore, GTS B may be a promising candidate molecule to develop leading compounds for the treatment of aging and age-related disorders.

Haploinsufficiency of the sex-determining genes at MATα restricts genome expansion in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, mating type of haploid cells is determined by the presence or absence of the MATα idiotype containing MATα1 and MATα2, which encode the transcription factors. These proteins are characterized by rapid turnover, but the physiological relevance of this property remains unclear. Here, we show a direct link between their intracellular levels and sexual stability. Polyploid cells with fewer MATα copies had unstable sexual phenotypes, causing morphological changes and an increase in cell death; these effects were mediated by hyperactivation of the mating pheromone response pathway. Thus, the MATα1 and MATα2 genes are haploinsufficient genes, and the reduction in their product levels causes sex fluctuation. Chromosome III harboring the mating type locus is the most prone to loss in diploids. We propose that the haploinsufficiency of MATα compensates for the drop-out prone nature of chromosome III, thereby suppressing speciation through increased genome size via polyploidization.

Genomic profile of radiation-induced early-onset mouse B-cell lymphoma recapitulates features of Philadelphia chromosome-like acute lymphoblastic leukemia in humans.

Epidemiological studies have revealed a radiation-related increase in the risk of developing acute lymphoblastic leukemia (ALL). Our recent study revealed early induction and increased risk of precursor B-cell (pB) lymphomas in mice after radiation exposure. However, the genomic landscape of radiation-induced B-cell lymphomas remains unclear. To identify the relevant genetic alterations in mice, whole-exome sequencing was performed on both early-onset and late-onset B-cell lymphomas that developed spontaneously or after gamma-irradiation. In addition to multiple driver mutations, the data revealed that interstitial deletion of chromosome 4, including Pax5, and missense mutations in Jak3 are unique genomic alterations in radiation-induced, early-onset B-cell lymphomas. RNA sequencing revealed a pB-cell-type gene-expression profile with no involvement of known fusion genes for human ALLs in the early-onset B-cell lymphomas. Activation of Jak3/Stat5 signaling in early-onset B-cell lymphomas was validated using western capillary electrophoresis. Those features were similar to those of Philadelphia chromosome-like ALL. Our data suggest a critical role for Pax5 loss-of-function mutations in initiating B-cell leukemogenesis coupled with activation of Jak3/Stat5 signaling as a basis for the rapid development of radiation-induced pB-ALL. These molecular signatures for radiation-induced cancers will inform both risk assessment and potential targeted therapies for pB-ALL.

Inokosterone from Gentiana rigescens Franch Extends the Longevity of Yeast and Mammalian Cells via Antioxidative Stress and Mitophagy Induction.

In the present study, replicative lifespan and chronological lifespan assays of yeast were used to double-screen antiaging compounds from Gentiana rigescens Franch, a Chinese herb medicine. Inokosterone from G. rigescens Franch extended not only the replicative lifespan of K6001 yeast but also the chronological lifespan of YOM36 yeast. Furthermore, it can enhance the survival ability of mammalian cells. In order to understand the mechanism of action of this compound, this study focused on antioxidative stress and autophagy when performing the analysis. The increased cell survival rate under oxidative stress conditions, antioxidant enzyme activity and gene expression were observed in the inokosterone-treated groups. Meanwhile, the reactive oxygen species (ROS) and lipid peroxidation of yeast were obviously decreased. Additionally, the macroautophagy and mitophagy in YOM38-GFP-ATG8 yeast were increased upon inokosterone treatment, respectively. At the same time, the cleavage-free GFP from GFP-ATG8 in the cytoplasm and the ubiquitin of the mitochondria at the protein level were markedly enhanced after incubation with inokosterone. Furthermore, we investigated the effect of inokosterone on antioxidative stress and autophagy in mammalian cells, and the relationship between ROS and autophagy. The ROS, malondialdehyde (MDA) were significantly decreased, and the autophagosomes in mammalian cells were obviously increased after inokosterone treatment. The autophagosomes in ∆sod1 yeast with a K6001 background had no obvious changes, and the ROS and MDA of ∆sod1 yeast were increased compared with K6001 yeast. The increase of autophagosomes and the reduction of ROS and MDA in ∆sod1 yeast were observed after treatment with inokosterone. Meanwhile, the reduction of the ROS level and the increase of the SOD1 gene expression of K6001 yeast lacking autophagy were observed after treatment with inokosterone. In order to indicate whether the genes related to antioxidant enzymes and autophagy were involved in the antiaging effect of inokosterone, mutants of K6001 yeast were constructed to conduct a lifespan assay. The replicative lifespans of ∆sod1, ∆sod2, ∆uth1, ∆skn7, ∆gpx, ∆cat, ∆atg2, and ∆atg32 of K6001 yeast were not affected by inokosterone. These results suggest that inokosterone exerted an antiaging activity via antioxidative stress and increased autophagy activation; autophagy affected the ROS levels of yeast via the regulation of SOD1 gene expression.

Disruption of actin dynamics induces autophagy of the eukaryotic chaperonin TRiC/CCT.

Autophagy plays important role in the intracellular protein quality control system by degrading abnormal organelles and proteins, including large protein complexes such as ribosomes. The eukaryotic chaperonin tailless complex polypeptide 1 (TCP1) ring complex (TRiC), also called chaperonin-containing TCP1 (CCT), is a 1-MDa hetero-oligomer complex comprising 16 subunits that facilitates the folding of ~10% of the cellular proteome that contains actin. However, the quality control mechanism of TRiC remains unclear. To monitor the autophagic degradation of TRiC, we generated TCP1α-RFP-GFP knock-in HeLa cells using a CRISPR/Cas9-knock-in system with an RFP-GFP donor vector. We analyzed the autophagic degradation of TRiC under several stress conditions and found that treatment with actin (de)polymerization inhibitors increased the lysosomal degradation of TRiC, which was localized in lysosomes and suppressed by deficiency of autophagy-related genes. Furthermore, we found that treatment with actin (de)polymerization inhibitors increased the association between TRiC and unfolded actin, suggesting that TRiC was inactivated. Moreover, unfolded actin mutants were degraded by autophagy. Taken together, our results indicate that autophagy eliminates inactivated TRiC, serving as a quality control system.

Protocol for quantification of the lysosomal degradation of extracellular proteins into mammalian cells.

Endocytic internalization of extracellular proteins plays roles in signaling, nutrient uptake, immunity, and extracellular protein quality control. However, there are few protocols for analyzing the lysosomal degradation of extracellular protein. Here, we purified secreted proteins fused with pH-sensitive GFP and acid- and protease-resistant RFP from mammalian cells and describe an internalization assay for mammalian cells. This protocol enables quantification of cellular uptake and lysosomal degradation of protein-of-interest (POI) via cell biological and biochemical analyses. For full details on the use and execution of this protocol, please refer to Itakura et al. (2020).

Labeling and measuring stressed mitochondria using a PINK1-based ratiometric fluorescent sensor.

Mitochondria are essential organelles that carry out a number of pivotal metabolic processes and maintain cellular homeostasis. Mitochondrial dysfunction caused by various stresses is associated with many diseases such as type 2 diabetes, obesity, cancer, heart failure, neurodegenerative disorders, and aging. Therefore, it is important to understand the stimuli that induce mitochondrial stress. However, broad analysis of mitochondrial stress has not been carried out to date. Here, we present a set of fluorescent tools, called mito-Pain (mitochondrial PINK1 accumulation index), which enable the labeling of stressed mitochondria. Mito-Pain uses PTEN-induced putative kinase 1 (PINK1) stabilization on mitochondria and quantifies mitochondrial stress levels by comparison with PINK1-GFP, which is stabilized under mitochondrial stress, and RFP-Omp25, which is constitutively localized on mitochondria. To identify compounds that induce mitochondrial stress, we screened a library of 3374 compounds using mito-Pain and identified 57 compounds as mitochondrial stress inducers. Furthermore, we classified each compound into several categories based on mitochondrial response: depolarization, mitochondrial morphology, or Parkin recruitment. Parkin recruitment to mitochondria was often associated with mitochondrial depolarization and aggregation, suggesting that Parkin is recruited to heavily damaged mitochondria. In addition, many of the compounds led to various mitochondrial morphological changes, including fragmentation, aggregation, elongation, and swelling, with or without Parkin recruitment or mitochondrial depolarization. We also found that several compounds induced an ectopic response of Parkin, leading to the formation of cytosolic puncta dependent on PINK1. Thus, mito-Pain enables the detection of stressed mitochondria under a wide variety of conditions and provides insights into mitochondrial quality control systems.

Impact of the Antithrombotic Effects of Prasugrel on Mid-Term Vascular Healing in Acute Coronary Syndrome vs. Stable Coronary Artery Disease.

BACKGROUND: The impact of antiplatelet drug effects on mid-term local arterial responses following percutaneous coronary intervention (PCI) remains uncertain. We evaluated the impact of the platelet reactivity of prasugrel on mid-term vascular healing between acute coronary syndrome (ACS) and stable coronary artery disease (CAD).Methods and Results:We conducted a prospective, 12-center study in 125 patients with ACS and 126 patients with stable CAD who underwent PCI with an everolimus-eluting stent (EES) and received dual antiplatelet therapy (DAPT) with prasugrel and aspirin. Serial optical coherence tomography (OCT) was performed immediately after PCI and at the 9-month follow-up to assess the association of P2Y12reaction units (PRU) with the frequency of malapposed or uncovered struts and intrastent thrombi (IST). The incidence of abnormal mid-term OCT findings did not different between the ACS and CAD arms, regardless of clinical presentation, except that uncovered struts were more frequent in the ACS than CAD arm. PRU at PCI was significantly associated with the frequency of IST at follow-up, but not with uncovered and malapposed struts. PRU at PCI was the only independent predictor of IST detected at follow-up (odds ratio 1.009). CONCLUSIONS: In patients undergoing EES implantation and receiving prasugrel, achieving an adequate antiplatelet effect at the time of stent implantation may regulate thrombus formation throughout the follow-up period.

Ehretiquinone from Onosma bracteatum Wall Exhibits Antiaging Effect on Yeasts and Mammals through Antioxidative Stress and Autophagy Induction.

The antiaging benzoquinone-type molecule ehretiquinone was isolated in a previous study as a leading compound from the herbal medicine Onosma bracteatum wall. This paper reports the antiaging effect and mechanism of ehretiquinone by using yeasts, mammal cells, and mice. Ehretiquinone extends not only the replicative lifespan but also the chronological lifespan of yeast and the yeast-like chronological lifespan of mammal cells. Moreover, ehretiquinone increases glutathione peroxidase, catalase, and superoxide dismutase activity and reduces reactive oxygen species and malondialdehyde (MDA) levels, contributing to the lifespan extension of the yeasts. Furthermore, ehretiquinone does not extend the replicative lifespan of Δsod1, Δsod2, Δuth1, Δskn7, Δgpx, Δcat, Δatg2, and Δatg32 mutants of yeast. Crucially, ehretiquinone induces autophagy in yeasts and mice, thereby providing significant evidence on the antiaging effects of the molecule in the mammalian level. Concomitantly, the silent information regulator 2 gene, which is known for its contributions in prolonging replicative lifespan, was confirmed to be involved in the chronological lifespan of yeasts and participates in the antiaging activity of ehretiquinone. These findings suggest that ehretiquinone shows an antiaging effect through antioxidative stress, autophagy, and histone deacetylase Sir2 regulation. Therefore, ehretiquinone is a promising molecule that could be developed as an antiaging drug or healthcare product.

Early induction and increased risk of precursor B-cell neoplasms after exposure of infant or young-adult mice to ionizing radiation.

Epidemiological studies of atomic-bomb survivors have revealed an increased risk of lymphoid neoplasm (i.e. acute lymphoblastic leukemia) associated with radiation exposure. In particular, children are more susceptible to radiation-induced precursor lymphoid neoplasm than adults. Although ~75% of human lymphoid tumors are B-cell neoplasms, the carcinogenic risk associated with each stage of differentiation of B-cells after radiation exposure is poorly understood. Therefore, we irradiated mice at infancy or in young adulthood to investigate the effect of age at exposure on the risk of developing B-cell neoplasms. Histopathology was used to confirm the presence of lymphoid neoplasms, and the population of B-cell neoplasms was classified into the precursor B-cell (pro-B and pre-B cell) type and mature B-cell type, according to immunophenotype. The data revealed that precursor B-cell neoplasms were induced soon after radiation exposure in infancy or young adulthood, resulting in a greater risk of developing the neoplasms. This was particularly the case for the pro-B cell type after young adult exposure. Our findings suggest that exposure to radiation at young age increases the risk of developing precursor B-cell neoplasms in humans.

Gentiopicroside, a Secoiridoid Glycoside from Gentiana rigescens Franch, Extends the Lifespan of Yeast via Inducing Mitophagy and Antioxidative Stress.

Gentiopicroside (GPS), an antiaging secoiridoid glycoside, was isolated from Gentiana rigescens Franch, a traditional Chinese medicine. It prolonged the replicative and chronological lifespans of yeast. Autophagy, especially mitophagy, and antioxidative stress were examined to clarify the mechanism of action of this compound. The free green fluorescent protein (GFP) signal from the cleavage of GFP-Atg8 and the colocation signal of MitoTracker Red CMXRos and GFP were increased upon the treatment of GPS. The free GFP in the cytoplasm and free GFP and ubiquitin of mitochondria were significantly increased at the protein levels in the GPS-treated group. GPS increased the expression of an essential autophagy gene, ATG32 gene, but failed to extend the replicative and chronological lifespans of ATG32 yeast mutants. GPS increased the survival rate of yeast under oxidative stress condition; enhanced the activities of catalase, superoxide dismutase, and glutathione peroxidase; and decreased the levels of reactive oxygen species and malondialdehyde. The replicative lifespans of Δsod1, Δsod2, Δuth1, and Δskn7 were not affected by GPS. These results indicated that autophagy, especially mitophagy, and antioxidative stress are involved in the antiaging effect of GPS.

Heparan sulfate is a clearance receptor for aberrant extracellular proteins.

The accumulation of aberrant proteins leads to various neurodegenerative disorders. Mammalian cells contain several intracellular protein degradation systems, including autophagy and proteasomal systems, that selectively remove aberrant intracellular proteins. Although mammals contain not only intracellular but also extracellular proteins, the mechanism underlying the quality control of aberrant extracellular proteins is poorly understood. Here, using a novel quantitative fluorescence assay and genome-wide CRISPR screening, we identified the receptor-mediated degradation pathway by which misfolded extracellular proteins are selectively captured by the extracellular chaperone Clusterin and undergo endocytosis via the cell surface heparan sulfate (HS) receptor. Biochemical analyses revealed that positively charged residues on Clusterin electrostatically interact with negatively charged HS. Furthermore, the Clusterin-HS pathway facilitates the degradation of amyloid ß peptide and diverse leaked cytosolic proteins in extracellular space. Our results identify a novel protein quality control system for preserving extracellular proteostasis and highlight its role in preventing diseases associated with aberrant extracellular proteins.

Early and Mid-Term Vascular Responses to Optical Coherence Tomography-Guided Everolimus-Eluting Stent Implantation in Stable Coronary Artery Disease.

BACKGROUND: Analysis of pooled clinical data has shown the safety of 3 months of dual antiplatelet therapy with everolimus-eluting cobalt-chromium stents (Co-Cr EESs). This study evaluated early and mid-term vascular responses to Co-Cr EESs in patients with stable coronary artery disease. METHODS: The Multicenter Comparison of Early and Late Vascular Responses to Everolimus-Eluting Cobalt-Chromium Stent and Platelet Aggregation Studies in Patients With Stable Angina Managed as Elective Case (MECHANISM-Elective) study (NCT02014818) is a multicenter optical coherence tomography (OCT) registry. Enrolled patients were evaluated by OCT immediately after everolimus-eluting stent implantation were prospectively allocated to 1 month (n = 50) or 3 months (n = 50) OCT follow-up and then received a 12-month OCT evaluation. The incidences of intrastent thrombus (IS-Th) and irregular protrusion (IRP) were also assessed. RESULTS: The percentage of uncovered struts was 6.4% ± 10.3% at 1 month (P < 0.001 vs. postprocedure) and 0.5% ± 0.9% at 12 months (P < 0.001 vs. 1 month). The corresponding values in the 3-month cohort were 2.0% ± 2.5% (P < 0.001 vs. postprocedure) and 0.5% ± 1.5% (P < 0.001 vs. 3 months). The incidence of IS-Th was 32.7% at 1 month, 5.4% at 3 months, and 2.0% at 12 months. IRP was observed in 21.8% of patients post-EES but had totally resolved at 1, 3, and 12 months. CONCLUSION: Early and mid-term vascular reactions after Co-Cr EES implantation in stable patients with coronary artery disease in the MECHANISM-Elective included dynamic resolution of IS-Th and IRP and rapid decrease in uncovered struts. Thus, EES may allow shortening of dual antiplatelet therapy duration less than 3 months in this patient subset.

Identification of a factor controlling lysosomal homeostasis using a novel lysosomal trafficking probe.

Lysosomes are largely responsible for significant degradation of intracellular and extracellular proteins via the secretory pathway, autophagy, and endocytosis. Therefore, dysregulation of lysosomal homeostasis influences diverse cellular functions. However, a straightforward and quantitative method to measure the integrity of the lysosomal pathway has not been developed. Here, we report the plasmid-based lysosomal-METRIQ (MEasurement of protein Transporting integrity by RatIo Quantification) probe that enables simple quantification of lysosomal integrity by lysosomal green and cytosolic red fluorescent proteins using a flow cytometer. In cultured cells, the lysosomal-METRIQ probe detected not only suppression of the lysosomal pathway but also upregulation of lysosomal activity such as lysosomal biogenesis. To identify factors involved in lysosomal homeostasis, we carried out compound screening and found that the cyclin-dependent kinase (CDK) inhibitors kenpaullone and purvalanol A induce synthesis of cathepsin D and an increase in the number of lysosomes. Subsequent studies revealed that CDK5 maintains lysosomal homeostasis independently of cell cycle arrest. Our results suggest that the lysosomal-METRIQ probe is an effective and efficient tool for measuring lysosomal activity in mammalian cells.