Platycodi Radix Extract Prevents Hepatic Steatosis by Enhancing Bile Acid Synthesis in a High-Fat Diet-Induced Fatty Liver Mouse Model.

We aimed to identify the mechanism underlying the preventive effects of non-alcoholic fatty liver disease (NAFLD) through Platycodi Radix consumption using liver proteomic and bioinformatic analysis. C57BL/6J mice were categorized into three groups: those receiving a standard chow diet (NCD), those on a high-fat diet (HFD), and those on an HFD supplemented with 5% Platycodi Radix extract (PRE). After a 12-week period, PRE-fed mice exhibited a noteworthy prevention of hepatic steatosis. Protein identification and quantification in liver samples were conducted using LC-MS/MS. The identified proteins were analyzed through Ingenuity Pathway Analysis software, revealing a decrease in proteins associated with FXR/RXR activation and a concurrent increase in cholesterol biosynthesis proteins in the PRE-treated mouse liver. Subsequent network analysis predicted enhanced bile acid synthesis from these proteins. Indeed, the quantity of bile acids, which was reduced in HFD conditions, increased in the PRE group, accompanied by an elevation in the expression of synthesis-related proteins. Our findings suggest that the beneficial effects of PRE in preventing hepatic steatosis may be mediated, at least in part, through the modulation of FXR/RXR activation, cholesterol biosynthesis, and bile acid synthesis pathways.

Oncogenic Impact of TONSL, a Homologous Recombination Repair Protein at the Replication Fork, in Cancer Stem Cells.

We investigated the role of TONSL, a mediator of homologous recombination repair (HRR), in stalled replication fork double-strand breaks (DSBs) in cancer. Publicly available clinical data (tumors from the ovary, breast, stomach and lung) were analyzed through KM Plotter, cBioPortal and Qomics. Cancer stem cell (CSC)-enriched cultures and bulk/general mixed cell cultures (BCCs) with RNAi were employed to determine the effect of TONSL loss in cancer cell lines from the ovary, breast, stomach, lung, colon and brain. Limited dilution assays and ALDH assays were used to quantify the loss of CSCs. Western blotting and cell-based homologous recombination assays were used to identify DNA damage derived from TONSL loss. TONSL was expressed at higher levels in cancer tissues than in normal tissues, and higher expression was an unfavorable prognostic marker for lung, stomach, breast and ovarian cancers. Higher expression of TONSL is partly associated with the coamplification of TONSL and MYC, suggesting its oncogenic role. The suppression of TONSL using RNAi revealed that it is required in the survival of CSCs in cancer cells, while BCCs could frequently survive without TONSL. TONSL dependency occurs through accumulated DNA damage-induced senescence and apoptosis in TONSL-suppressed CSCs. The expression of several other major mediators of HRR was also associated with worse prognosis, whereas the expression of error-prone nonhomologous end joining molecules was associated with better survival in lung adenocarcinoma. Collectively, these results suggest that TONSL-mediated HRR at the replication fork is critical for CSC survival; targeting TONSL may lead to the effective eradication of CSCs.

Dual Impact of IGF2 on Alveolar Stem Cell Function during Tobacco-Induced Injury Repair and Development of Pulmonary Emphysema and Cancer.

Pulmonary emphysema is a destructive inflammatory disease primarily caused by cigarette smoking (CS). Recovery from CS-induced injury requires proper stem cell (SC) activities with a tightly controlled balance of proliferation and differentiation. Here we show that acute alveolar injury induced by two representative tobacco carcinogens, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene (N/B), increased IGF2 expression in alveolar type 2 (AT2) cells to promote their SC function and facilitate alveolar regeneration. Autocrine IGF2 signaling upregulated Wnt genes, particularly Wnt3, to stimulate AT2 proliferation and alveolar barrier regeneration after N/B-induced acute injury. In contrast, repetitive N/B exposure provoked sustained IGF2-Wnt signaling through DNMT3A-mediated epigenetic control of IGF2 expression, causing a proliferation/differentiation imbalance in AT2s and development of emphysema and cancer. Hypermethylation of the IGF2 promoter and overexpression of DNMT3A, IGF2, and the Wnt target gene AXIN2 were seen in the lungs of patients with CS-associated emphysema and cancer. Pharmacologic or genetic approaches targeting IGF2-Wnt signaling or DNMT prevented the development of N/B-induced pulmonary diseases. These findings support dual roles of AT2 cells, which can either stimulate alveolar repair or promote emphysema and cancer depending on IGF2 expression levels. SIGNIFICANCE: IGF2-Wnt signaling plays a key role in AT2-mediated alveolar repair after cigarette smoking-induced injury but also drives pathogenesis of pulmonary emphysema and cancer when hyperactivated.

Ultrasensitive biosensing platform for Mycobacterium tuberculosis detection based on functionalized graphene devices.

Tuberculosis (TB) has high morbidity as a chronic infectious disease transmitted mainly through the respiratory tract. However, the conventional diagnosis methods for TB are time-consuming and require specialists, making the diagnosis of TB with point-of-care (POC) detection difficult. Here, we developed a graphene-based field-effect transistor (GFET) biosensor for detecting the MPT64 protein of Mycobacterium tuberculosis with high sensitivity as a POC detection platform for TB. For effective conjugation of antibodies, the graphene channels of the GFET were functionalized by immobilizing 1,5-diaminonaphthalene (1,5-DAN) and glutaraldehyde linker molecules onto the graphene surface. The successful immobilization of linker molecules with spatial uniformity on the graphene surface and subsequent antibody conjugation were confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy. The GFET functionalized with MPT64 antibodies showed MPT64 detection with a detection limit of 1 fg/mL in real-time, indicating that the GFET biosensor is highly sensitive. Compared to rapid detection tests (RDT) and enzyme-linked immunosorbent assays, the GFET biosensor platform developed in this study showed much higher sensitivity but much smaller dynamic range. Due to its high sensitivity, the GFET biosensor platform can bridge the gap between time-consuming molecular diagnostics and low-sensitivity RDT, potentially aiding in early detection or management of relapses in infectious diseases.

Screening of the siGPCR library in combination with cisplatin against lung cancers.

The screening of siRNAs targeting 390 human G protein-coupled receptors (GPCRs) was multiplexed in combination with cisplatin against lung cancer cells. While the cell viability measure hardly captured the anticancer effect of siGPCRs, the direct cell count revealed the anticancer potential of diverse GPCRs (46 hits with > twofold growth inhibition, p-value < 0.01). In combined treatment with cisplatin, siRNAs against five genes (ADRA2A, F2RL3, NPSR1, NPY and TACR3) enhanced the anti-proliferation efficacy on cancer cells and reduced the self-recovery ability of surviving cells after the removal of the combined treatment. Further on-target validation confirmed that the knockdown of TACR3 expression exhibited anticancer efficacy under both single and combined treatment with cisplatin. Q-omics ( http://qomics.io ) analysis showed that high expression of TACR3 was unfavorable for patient survival, particularly with mutations in GPCR signaling pathways. The present screening data provide a useful resource for GPCR targets and biomarkers for improving the efficacy of cisplatin treatment.

The First Evaluation of Proteinase K-Resistant Prion Protein (PrPSc) in Korean Appendix Specimens.

Background and Objectives: Prion diseases are fatal neurodegenerative disorders caused by the abnormal proteinase K-resistant prion protein (PrPSc). Since variant Creutzfeldt-Jakob disease (CJD) was first reported in the United Kingdom (UK) in 1996, the occurrence of variant CJD has been reported in over 10 countries. To date, variant CJD has not been reported in Korea. However, the E211K somatic mutation in the prion protein gene (PRNP), which is related to bovine spongiform encephalopathy (BSE), was reported in Korean Holstein cattle, and atypical BSE, which is supposed to be sporadic BSE, has been occurring in many countries, including Japan and the USA. These results suggest that BSE may occur naturally in Korea. Thus, we performed a preemptive PrPSc test in appendix specimens to diagnose variant CJD in a Korean population. Materials and Methods: In the present study, we investigated CJD-related mutations and polymorphisms of the PRNP gene and carried out an examination on PrPSc in appendix specimens of Korean patients after appendectomy. Results: In all Korean appendix specimens tested, PrPSc bands were not detected. Conclusion: To the best of our knowledge, this was the first evaluation of PrPSc in Korean appendix specimens.

All-Printed Flexible Memristor with Metal-Non-Metal-Doped TiO2 Nanoparticle Thin Films.

A memristor is a fundamental electronic device that operates like a biological synapse and is considered as the solution of classical von Neumann computers. Here, a fully printed and flexible memristor is fabricated by depositing a thin film of metal-non-metal (chromium-nitrogen)-doped titanium dioxide (TiO2). The resulting device exhibited enhanced performance with self-rectifying and forming free bipolar switching behavior. Doping was performed to bring stability in the performance of the memristor by controlling the defects and impurity levels. The forming free memristor exhibited characteristic behavior of bipolar resistive switching with a high on/off ratio (2.5 × 103), high endurance (500 cycles), long retention time (5 × 103 s) and low operating voltage (±1 V). Doping the thin film of TiO2 with metal-non-metal had a significant effect on the switching properties and conduction mechanism as it directly affected the energy bandgap by lowering it from 3.2 eV to 2.76 eV. Doping enhanced the mobility of charge carriers and eased the process of filament formation by suppressing its randomness between electrodes under the applied electric field. Furthermore, metal-non-metal-doped TiO2 thin film exhibited less switching current and improved non-linearity by controlling the surface defects.

Usefulness of an Additional Filter Created Using 3D Printing for Whole-Body X-ray Imaging with a Long-Length Detector.

We recently developed a long-length detector that combines three detectors and successfully acquires whole-body X-ray images. Although the developed detector system can efficiently acquire whole-body images in a short time, it may show problems with diagnostic performance in some areas owing to the use of high-energy X-rays during whole-spine and long-length examinations. In particular, during examinations of relatively thin bones, such as ankles, with a long-length detector, the image quality deteriorates because of an increase in X-ray transmission. An additional filter is primarily used to address this limitation, but this approach imposes a higher load on the X-ray tube to compensate for reductions in the radiation dose and the problem of high manufacturing costs. Thus, in this study, a newly designed additional filter was fabricated using 3D printing technology to improve the applicability of the long-length detector. Whole-spine anterior-posterior (AP), lateral, and long-leg AP X-ray examinations were performed using 3D-printed additional filters composed of 14 mm thick aluminum (Al) or 14 mm thick Al + 1 mm thick copper (Cu) composite material. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and radiation dose for the acquired X-ray images were evaluated to demonstrate the usefulness of the filters. Under all X-ray inspection conditions, the most effective data were obtained when the composite additional filter based on a 14 mm thick Al + 1 mm thick Cu material was used. We confirmed that an SNR improvement of up to 46%, CNR improvement of 37%, and radiation dose reduction of 90% could be achieved in the X-ray images obtained using the composite additional filter in comparison to the images obtained with no filter. The results proved that the additional filter made with a 3D printer was effective in improving image quality and reducing the radiation dose for X-ray images obtained using a long-length detector.

ARL2 is required for homologous recombination repair and colon cancer stem cell survival.

ARL2 regulates the dynamics of cytological components and is highly expressed in colon cancer tissues. Here, we report novel roles of ARL2 in the cell nucleus and colon cancer stem cells (CSCs). ARL2 is expressed at relatively low levels in K-RAS active colon cancer cells, but its expression is induced in CSCs. Depletion of ARL2 results in M phase arrest exclusively in non-CSC cultured cells; in addition, DNA break stress accumulates in CSCs leading to apoptosis. ARL2 expression is positively associated with the expression of all six RAD51 family genes, which are essential for homologous recombination repair (HRR). Furthermore, ARL2 is required for HRR and detected within chromatin compartments. These results demonstrate the requirement of ARL2 in colon CSC maintenance, which possibly occurs through mediating double-strand break DNA repair in the nucleus.

Highly Sensitive and Stable Humidity Sensor Based on the Bi-Layered PVA/Graphene Flower Composite Film.

Two-dimensional (2D) materials and their composites have gained significant importance as the functional layer of various environmental sensors and nanoelectronics owing to their unique properties. This work reports for the first time a highly sensitive, fast, and stable humidity sensor based on the bi-layered active sensing area composed of graphene flower (GF) and poly (vinyl alcohol) PVA thin films for multifunctional applications. The GF/PVA humidity sensor exhibited stable impedance response over 15 days, for a relative humidity (RH) range of (40-90% RH) under ambient operating conditions. The proposed bi-layered humidity sensor also exhibited an ultra-high capacitive sensitivity response of the 29 nF/%RH at 10 kHz and fast transient response of 2 s and 3.5 s, respectively. Furthermore, the reported sensor also showed a good response towards multi-functional applications such as non-contact skin humidity and mouth breathing detection.

Identification of a Novel Antigen for Serological Diagnosis of Scrub Typhus.

Scrub typhus is an acute infectious disease caused by the bacterium Orientia tsutsugamushi, which is widely distributed in northern, southern, and eastern Asia. Early diagnosis is essential because the average case fatality rate is usually >10% but can be as high as 45% if antimicrobial treatment is delayed. Although an O. tsutsugamushi 56-kDa type-specific antigen (TSA) is commonly used for serological diagnosis of scrub typhus, the 56-kDa TSA shows variations among O. tsutsugamushi strains, which may lead to poor diagnostic results. Therefore, the discovery of new antigenic proteins may improve diagnostic accuracy. In this study, we identified an O. tsutsugamushi 27 kDa antigen through an immunoinformatic approach and verified its diagnostic potential using patient samples. Compared with the O. tsutsugamushi 56-kDa antigen, the new 27-kDa antigen showed better diagnostic specificity with similar diagnostic sensitivity. Therefore, the O. tsutsugamushi 27-kDa antigen shows potential as a novel serological diagnostic antigen for scrub typhus, providing higher diagnostic accuracy for O. tsutsugamushi than the 56-kDa antigen.

Highly Efficient and Wide Range Humidity Response of Biocompatible Egg White Thin Film.

Biopolymers are a solution to solve the increasing problems caused by the advances and revolution in the electronic industry owing to the use of hazardous chemicals. In this work, we have used egg white (EW) as the low-cost functional layer of a biocompatible humidity sensor and deposited it on gold (Au) interdigitated electrodes (IDEs) patterned through the state-of-the-art fabrication technology of thermal vacuum evaporation. The presence of hydrophilic proteins inside the thin film of EW makes it an attractive candidate for sensing humidity. Usually, the dependence of the percentage of relative humidity (%RH) on the reliability of measurement setup is overlooked for impedimetric humidity sensors but we have used a modified experimental setup to enhance the uniformity of the obtained results. The characteristics of our device include almost linear response with a quick response time (1.2 s) and fast recovery time (1.7 s). High sensitivity of 50 kΩ/%RH was achieved in the desirable detection range of 10-85%RH. The device size was intentionally kept small for its potential integration in a marketable chip. Results for the response of our fabricated sensor for dry and wet fingertips, along with determining the rate of breathing through the mouth, are part of this study, making it a potential device for health monitoring.

A Full-Range Flexible and Printed Humidity Sensor Based on a Solution-Processed P(VDF-TrFE)/Graphene-Flower Composite.

A novel composite based on a polymer (P(VDF-TrFE)) and a two-dimensional material (graphene flower) was proposed as the active layer of an interdigitated electrode (IDEs) based humidity sensor. Silver (Ag) IDEs were screen printed on a flexible polyethylene terephthalate (PET) substrate followed by spin coating the active layer of P(VDF-TrFE)/graphene flower on its surface. It was observed that this sensor responds to a wide relative humidity range (RH%) of 8-98% with a fast response and recovery time of 0.8 s and 2.5 s for the capacitance, respectively. The fabricated sensor displayed an inversely proportional response between capacitance and RH%, while a directly proportional relationship was observed between its impedance and RH%. P(VDF-TrFE)/graphene flower-based flexible humidity sensor exhibited high sensitivity with an average change of capacitance as 0.0558 pF/RH%. Stability of obtained results was monitored for two weeks without any considerable change in the original values, signifying its high reliability. Various chemical, morphological, and electrical characterizations were performed to comprehensively study the humidity-sensing behavior of this advanced composite. The fabricated sensor was successfully used for the applications of health monitoring and measuring the water content in the environment.

A novel synthetic microtubule inhibitor exerts antiproliferative effects in multidrug resistant cancer cells and cancer stem cells.

The success of cancer chemotherapy is limited by multidrug resistance (MDR), which is mainly caused by P-glycoprotein (P-gp) overexpression. In the present study, we describe a novel microtubule inhibitor, 5-(N-methylmaleimid-3-yl)-chromone (SPC-160002), that can be used to overcome MDR. A synthetic chromone derivative, SPC-160002, showed a broad spectrum of anti-proliferative effects on various human cancer cells without affecting P-gp expression and its drug efflux function. Treatment with SPC-160002 arrested the cell cycle at the M phase, as evidenced using fluorescence-activated cell sorting analysis, and increased the levels of mitotic marker proteins, including cyclin B, pS10-H3, and chromosomal passenger complex. This mitotic arrest by SPC-160002 was mediated by promoting and stabilizing microtubule polymerization, similar to the mechanism observed in case of taxane-based drugs. Furthermore, SPC-160002 suppressed the growth and sphere-forming activity of cancer stem cells. Our data herein strongly suggest that SPC-160002, a novel microtubule inhibitor, can be used to overcome MDR and can serve as an attractive candidate for anticancer drugs.

Freestanding and Flexible ß-MnO2@Carbon Sheet for Application as a Highly Sensitive Dimethyl Methylphosphonate Sensor.

Research on wearable sensor systems is mostly conducted on freestanding polymer substrates such as poly(dimethylsiloxane) and poly(ethylene terephthalate). However, the use of these polymers as substrates requires the introduction of transducer materials on their surface, which causes many problems related to the contact with the transducer components. In this study, we propose a freestanding flexible sensor electrode based on a ß-MnO2-decorated carbon nanofiber sheet (ß-MnO2@CNF) to detect dimethyl methylphosphonate (DMMP) as a nerve agent simulant. To introduce MnO2 on the surface of the substrate, polypyrrole coated on poly(acrylonitrile) (PPy@PAN) was reacted with a MnO2 precursor. Then, phase transfer of PPy@PAN and MnO2 to carbon and ß-MnO2, respectively, was induced by heat treatment. The ß-MnO2@CNF sheet electrode showed excellent sensitivity toward the target analyte DMMP (down to 0.1 ppb), as well as high selectivity, reversibility, and stability.

Species Prioritization Based on Spectral Dissimilarity: A Case Study of Polyporoid Fungal Species.

Biological species collections are critical for natural product drug discovery programs. However, prioritization of target species in massive collections remains difficult. Here, we introduce an untargeted metabolomics-based prioritization workflow that uses MS/MS molecular networking to estimate scaffold-level distribution. As a demonstration, we applied the workflow to 40 polyporoid fungal species. Nine species were prioritized as candidates based on the chemical structural and compositional similarity (CSCS) metric. Most of the selected species showed relatively higher richness and uniqueness of metabolites than those of the others. Cryptoporus volvatus, one of the prioritized species, was investigated further. The chemical profiles of the extracts of C. volvatus culture and fruiting bodies were compared, and it was shown that derivative-level diversity was higher in the fruiting bodies; meanwhile, scaffold-level diversity was similar. This showed that the compounds found from a cultured fungus can also be isolated in wild mushrooms. Targeted isolation of the fruiting body extract yielded three unknown (1-3) and six known (4-9) cryptoporic acid derivatives, which are drimane-type sesquiterpenes with isocitric acid moieties that have been reported in this species. Cryptoporic acid T (1) is a trimeric cryptoporic acid reported for the first time. Compounds 2 and 5 exhibited cytotoxicity against HCT-116 cell lines with IC50 values of 4.3 and 3.6 µM, respectively.

Targeting a Lipid Desaturation Enzyme, SCD1, Selectively Eliminates Colon Cancer Stem Cells through the Suppression of Wnt and NOTCH Signaling.

The elimination of the cancer stem cell (CSC) population may be required to achieve better outcomes of cancer therapy. We evaluated stearoyl-CoA desaturase 1 (SCD1) as a novel target for CSC-selective elimination in colon cancer. CSCs expressed more SCD1 than bulk cultured cells (BCCs), and blocking SCD1 expression or function revealed an essential role for SCD1 in the survival of CSCs, but not BCCs. The CSC potential selectively decreased after treatment with the SCD1 inhibitor in vitro and in vivo. The CSC-selective suppression was mediated through the induction of apoptosis. The mechanism leading to selective CSC death was investigated by performing a quantitative RT-PCR analysis of 14 CSC-specific signaling and marker genes after 24 and 48 h of treatment with two concentrations of an inhibitor. The decrease in the expression of Notch1 and AXIN2 preceded changes in the expression of all other genes, at 24 h of treatment in a dose-dependent manner, followed by the downregulation of most Wnt- and NOTCH-signaling genes. Collectively, we showed that not only Wnt but also NOTCH signaling is a primary target of suppression by SCD1 inhibition in CSCs, suggesting the possibility of targeting SCD1 against colon cancer in clinical settings.

Identification and functional study of genetic polymorphisms in cyclic nucleotide phosphodiesterase 3A (PDE3A).

Phosphodiesterase 3A (PDE3A) is an enzyme that plays an important role in the regulation of cyclic adenosine monophosphate (cAMP)-mediated intracellular signaling in cardiac myocytes and platelets. PDE3A hydrolyzes cAMP, which results in a decrease in intracellular cAMP levels and leads to platelet activation. Whole-exome sequencing of 50 DNA samples from a healthy Korean population revealed a total of 13 single nucleotide polymorphisms including five missense variants, D12N, Y497C, H504Q, C707R, and A980V. Recombinant proteins for the five variants of PDE3A (and wild-type protein) were expressed in a FreeStyle 293 expression system with site-directed mutagenesis. The expression of the recombinant PDE3A proteins was confirmed with Western blotting. Catalytic activity of the PDE3A missense variants and wild-type enzyme was measured with a PDE-based assay. Effects of the missense variants on the inhibition of PDE3A activity by cilostazol were also investigated. All variant proteins showed reduced activity (33-53%; p < .0001) compared to the wild-type protein. In addition, PDE3A activity was inhibited by cilostazol in a dose-dependent manner and was further suppressed in the missense variants. Specifically, the PDE3A Y497C showed significantly reduced activity, consistent with the predictions of in silico analyses. The present study provides evidence that individuals carrying the PDE3A Y497C variant may have lower enzyme activity for cAMP hydrolysis, which could cause interindividual variation in cAMP-mediated physiological functions.

Application of multi-omics technology for the elucidation of anti-pneumococcal activity of 3-acyl-2-phenylamino-1,4-dihydroquinolin-4-one (APDQ) derivative against Streptococcus pneumoniae.

Streptococcus pneumoniae is one of Gram-positive pathogen that causes invasive pneumococcal disease. Nowadays, many S. pneumoniae strains are resistant to commonly used antibiotics such as ß-lactams and macrolides. 3-Acyl-2-phenylamino-1,4-dihydroquinolin-4-one (APDQ) derivatives are known as novel chemicals having anti-pneumococcal activity against S. pneumoniae. The underlying mechanism of the anti-pneumococcal activity of this inhibitor remains unknown. Therefore, we tried to find the anti-pneumococcal mechanism of APDQ230122, one of the APDQ derivatives active against S. pneumoniae. We performed transcriptomic analysis (RNA-Seq) and proteomic analysis (LC-MS/MS analysis) to get differentially expressed genes (DEG) and differentially expressed proteins (DEP) of S. pneumoniae 521 treated with sub-inhibitory concentrations of APDQ230122 and elucidated the comprehensive expression changes of genes and proteins using multi-omics analysis. As a result, genes or proteins of peptidoglycan biosynthesis and DNA replication were significantly down-regulated. Electron microscopy analysis revealed that the structure of peptidoglycan was damaged by APDQ230122 in a chemical concentration-dependent manner. Therefore, we suggest peptidoglycan biosynthesis is a major target of APDQ230122. Multi-omics analysis can provide us useful information to elucidate anti-pneumococcal activity of APDQ230122.

Ginsenoside Rb1 and Rb2 upregulate Akt/mTOR signaling-mediated muscular hypertrophy and myoblast differentiation.

BACKGROUND: As a process of aging, skeletal muscle mass and function gradually decrease. It is reported that ginsenoside Rb1 and Rb2 play a role as AMP-activated protein kinase activator, resulting in regulating glucose homeostasis, and Rb1 reduces oxidative stress in aged skeletal muscles through activating the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. We examined the effects of Rb1 and Rb2 on differentiation of the muscle stem cells and myotube formation. METHODS: C2C12 myoblasts treated with Rb1 and/or Rb2 were differentiated and induced to myotube formation, followed by immunoblotting for myogenic marker proteins, such as myosin heavy chain, MyoD, and myogenin, or immunostaining for myosin heavy chain or immunoprecipitation analysis for heterodimerization of MyoD/E-proteins. RESULTS: Rb1 and Rb2 enhanced myoblast differentiation through accelerating MyoD/E-protein heterodimerization and increased myotube hypertrophy, accompanied by activation of Akt/mammalian target of rapamycin signaling. In addition, Rb1 and Rb2 induced the MyoD-mediated transdifferentiation of the rhabdomyosarcoma cells into myoblasts. Furthermore, co-treatment with Rb1 and Rb2 had synergistically enhanced myoblast differentiation through Akt activation. CONCLUSION: Rb1 and Rb2 upregulate myotube growth and myogenic differentiation through activating Akt/mammalian target of rapamycin signaling and inducing myogenic conversion of fibroblasts. Thus, our first finding indicates that Rb1 and Rb2 have strong potential as a helpful remedy to prevent and treat muscle atrophy, such as age-related muscular dystrophy.