Online learning control by association and reinforcement

This paper focuses on a systematic treatment for developing a generic online learning control system based on the fundamental principle of reinforcement learning or more specifically neural dynamic programming. This online learning system improves its performance over time in two aspects: 1) it learns from its own mistakes through the reinforcement signal from the external environment and tries to reinforce its action to improve future performance; and 2) system states associated with the positive reinforcement is memorized through a network learning process where in the future, similar states will be more positively associated with a control action leading to a positive reinforcement. A successful candidate of online learning control design is introduced. Real-time learning algorithms is derived for individual components in the learning system. Some analytical insight is provided to give guidelines on the learning process took place in each module of the online learning control system.

Associations of egg consumption with cardiovascular disease in a cohort study of 0.5 million Chinese adults

OBJECTIVE

To examine the associations between egg consumption and cardiovascular disease (CVD), ischaemic heart disease (IHD), major coronary events (MCE), haemorrhagic stroke as well as ischaemic stroke.

METHODS

During 2004-2008, over 0.5 million adults aged 30-79 years were recruited from 10 diverse survey sites in China. Participants were asked about the frequency of egg consumption and were followed up via linkages to multiple registries and active investigation. Among 461 213 participants free of prior cancer, CVD and diabetes, a total of 83 977 CVD incident cases and 9985 CVD deaths were documented, as well as 5103 MCE. Stratified Cox regression was performed to yield adjusted hazard ratios for CVD endpoints associated with egg consumption.

RESULTS

At baseline, 13.1% of participants reported daily consumption (usual amount 0.76 egg/day) and 9.1% reported never or very rare consumption (usual amount 0.29 egg/day). Compared with non-consumers, daily egg consumption was associated with lower risk of CVD (HR 0.89, 95% CI 0.87 to 0.92). Corresponding multivariate-adjusted HRs (95% CI) for IHD, MCE, haemorrhagic stroke and ischaemic stroke were 0.88 (0.84 to 0.93), 0.86 (0.76 to 0.97), 0.74 (0.67 to 0.82) and 0.90 (0.85 to 0.95), respectively. There were significant dose-response relationships of egg consumption with morbidity of all CVD endpoints (P for linear trend <0.05). Daily consumers also had an 18% lower risk of CVD death and a 28% lower risk of haemorrhagic stroke death compared to non-consumers.

CONCLUSION

Among Chinese adults, a moderate level of egg consumption (up to <1 egg/day) was significantly associated with lower risk of CVD, largely independent of other risk factors.

Induction of acetylcholine receptor gene expression by ARIA requires activation of mitogen-activated protein kinase

Transcription of genes encoding nicotinic acetylcholine receptor (AChR) subunits (alpha, beta, gamma or epsilon, and delta) is highest in nuclei localized to the synaptic region of the muscle, which contributes to maintain a high density of AChRs at the postjunctional membrane. ARIA (AChR inducing activity) is believed to be the trophic factor utilized by motor neurons to stimulate AChR synthesis in the subsynaptic area. To elucidate the signaling mechanism initiated by ARIA, we established stable C2C12 cell lines carrying the nuclear lacZ gene under the control of the mouse epsilon subunit promoter or chicken alpha subunit promoter. ARIA stimulated tyrosine phosphorylation of erbB proteins in these C2C12 cells within 15 s with a peak at 5 min. Immediately following tyrosine phosphorylation of erbB proteins, mitogen-activated protein (MAP) kinase was activated which occurred within 30 s and peaked at 8 min after ARIA stimulation. Concomitantly, expression of AChR genes was induced by ARIA. ARIA-induced AChR subunit transgene expression was observed only in differentiated myotubes and not in myoblasts, suggesting that downstream signaling component(s) are regulated in a manner dependent on the myogenic program. Inhibition of the MAP kinase activity by using a specific MAP kinase kinase inhibitor or by overexpressing dominant negative mutants of Raf or MAP kinase kinase attenuated or abolished the ARIA-induced activation of AChR alpha and epsilon subunit gene expression. These results indicate that regulation of AChR gene expression by ARIA in C2C12 cells requires activation of the MAP kinase signaling pathway.

A computationally efficient method for solving the redundant problem in biomechanics

Determining the optimal set of musculotendon forces with which to produce a forward dynamic simulation of movement typically involves a huge investment of time and computational resources. A new, computationally efficient method is proposed that simultaneously achieves the desired trajectory and the dynamically optimized set of muscle stresses, and hence forces, according to the maximal endurance criterion function of Crowninshield and Brand (1981). Muscle-induced accelerations of the system resulting from unit stress contractions of individual muscles are superposed via the new pseudoinverse method to yield the desired motion trajectory. The method is tested on a control problem involving a five degree-of-freedom (DOF), 30 muscle, upper extremity model, which incorporates a dual rigid-body forearm to represent pronation and supination more adequately. The pseudoinverse method delivered the desired motion to within 0.25 degrees for each DOF during a three-second simulation. It is anticipated that the methodology can be easily and accurately applied to other highly redundant optimal control problems in biomechanics.

Validation of the in vitro gastrointestinal (IVG) method to estimate relative bioavailable lead in contaminated soils

The effect of the dosing vehicle (e.g., dough) on the ability of an in vitro gastrointestinal (IVG) method to predict relative bioavailable Pb associated with soil ingestion was evaluated. Bioaccessible Pb determined by the IVG method was compared with relative bioavailable Pb measured from dosing trials using juvenile swine for 18 contaminated soils ranging from 1270 to 14200 mg Pb kg(-1). Bioaccessible Pb was measured in the IVG gastric extraction (GE) and intestinal extraction (IE) solutions. Mean bioaccessible Pb values were 32.2% for GE without dough, 23.0% for GE with dough, 1.06% for IE without dough, and 0.56% for IE with dough. It is possible that phytic acid associated with the dough addition decreased bioaccessible Pb. In vivo relative bioavailable Pb ranges for different swine tissues were 1 to 87% for blood, 0 to 110% for liver, 1 to 124% for kidney, and 0.04 to 94% for bone. Strong linear relationships between IVG GE Pb with dough (r > 0.76, P < 0.0002), IVG IE Pb with dough (r > 0.56, P < 0.015), and IVG GE Pb without dough (r > 0.81, P < 0.0001) and in vivo bioavailable Pb as estimated with blood, kidney, liver, and bone were found. Inexpensive in vitro methods may be useful in providing an estimate of the variability in relative bioavailable Pb at a single study site. The IVG method can be used to estimate relative bioavailable Pb, As, and Cd in contaminated soil.

Analysis and synthesis of a class of discrete-time neural networks with multilevel threshold neurons

In contrast to the usual types of neural networks which utilize two states for each neuron, a class of synchronous discrete-time neural networks with multilevel threshold neurons is developed. A qualitative analysis and a synthesis procedure for the class of neural networks considered constitute the principal contributions of this paper. The applicability of the present class of neural networks is demonstrated by means of a gray level image processing example, where each neuron can assume one of sixteen values. When compared to the usual neural networks with two state neurons, networks which are endowed with multilevel neurons will, in general, for a given application, require fewer neurons and thus fewer interconnections. This is an important consideration in VLSI implementation.

Schistosoma japonicum triose-phosphate isomerase plasmid DNA vaccine protects pigs against challenge infection

The protective efficacy of a Schistosoma japonicum, Chinese strain, triose-phosphate isomerase (TPI) plasmid DNA vaccine was examined in naïve pigs. Pigs were vaccinated with the TPI DNA-plasmid alone, or in conjunction with IL-12 as pcDNA3.1-P35, pcDNA3.1-P40 plasmids via intramuscular injection. Control pigs were immunized with equivalent amounts of pcDNA3.1. Pigs were immunized 3 times at 21-day intervals and challenged 30 days after the final boost. Forty-five days post-challenge, pigs were sacrificed and perfused to compare adult worm burdens, female worm burdens, liver egg burdens and granuloma size. We found that pigs vaccinated with SjCTPI DNA alone had adult worm burdens reduced by 48.3% and that a further decrease in adult worm burdens was not seen in the group vaccinated with SjCTPI DNA in conjunction with IL-12 (46.2% reduction). The SjCTPI DNA vaccines had a more pronounced effect on reducing female worm burdens i.e. 53.6% SjCTPI alone and 59.6% for SjCTPI+IL-12. Vaccination with SjCTPI-DNA reduced liver eggs by 49.4% and this response was significantly enhanced by the addition of IL-12 (65.8% reduction in liver eggs). In addition to the dramatic protective effects seen in vaccinated pigs, we also noted that granuloma size was reduced by 42% in both groups. Thus, vaccination of pigs and other large animals in China with SjCTPI DNA vaccine will likely reduce transmission by reducing adult worm burdens and worm egg output and simultaneously reduce hepatic egg-associated pathology.

Tea consumption and risk of ischaemic heart disease

Objective

To prospectively examine the association between tea consumption and the risk of ischaemic heart disease (IHD).

Methods

Prospective study using the China Kadoorie Biobank; participants from 10 areas across China were enrolled during 2004–2008 and followed up until 31 December 2013. After excluding participants with cancer, heart disease and stroke at baseline, the present study included 199 293 men and 288 082 women aged 30–79 years at baseline. Information on IHD incidence was collected through disease registries and the new national health insurance databases.

Results

During a median follow-up of 7.2 years, we documented 24 665 (7.19 cases/1000 person-years) incident IHD cases and 3959 (1.13 cases/1000 person-years) major coronary events (MCEs). Tea consumption was associated with reduced risk of IHD and MCE. In the whole cohort, compared with participants who never consumed tea during the past 12 months, the multivariable-adjusted HRs and 95% CIs for less than daily and daily tea consumers were 0.97 (0.94 to 1.00) and 0.92 (0.88 to 0.95) for IHD, 0.92 (0.85 to 1.00) and 0.90 (0.82 to 0.99) for MCE. No linear trends in the HRs across the amount of tea were observed in daily consumers for IHD and MCE (P_Linear >0.05). The inverse association between tea consumption and IHD was stronger in rural (P_Interaction 0.006 for IHD, <0.001 for MCE), non-obese (P_Interaction 0.012 for MCE) and non-diabetes participants (P_Interaction 0.004 for IHD).

Conclusions

In this large prospective study, daily tea consumption was associated with a reduced risk of IHD.

A large-scale genome-wide association analysis of lung function in the Chinese population identifies novel loci and highlights shared genetic aetiology with obesity

BACKGROUND

Lung function is a heritable complex phenotype with obesity being one of its important risk factors. However, knowledge of their shared genetic basis is limited. Most genome-wide association studies (GWASs) for lung function have been based on European populations, limiting the generalisability across populations. Large-scale lung function GWASs in other populations are lacking.

METHODS

We included 100 285 subjects from the China Kadoorie Biobank (CKB). To identify novel loci for lung function, single-trait GWAS analyses were performed on forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC in the CKB. We then performed genome-wide cross-trait analysis between lung function and obesity traits (body mass index (BMI), BMI-adjusted waist-to-hip ratio and BMI-adjusted waist circumference) to investigate the shared genetic effects in the CKB. Finally, polygenic risk scores (PRSs) of lung function were developed in the CKB and their interaction with BMI's association on lung function were examined. We also conducted cross-trait analysis in parallel with the CKB using up to 457 756 subjects from the UK Biobank (UKB) for replication and investigation of ancestry-specific effects.

RESULTS

We identified nine genome-wide significant novel loci for FEV1, six for FVC and three for FEV1/FVC in the CKB. FEV1 and FVC showed significant negative genetic correlation with obesity traits in both the CKB and UKB. Genetic loci shared between lung function and obesity traits highlighted important biological pathways, including cell proliferation, embryo, skeletal and tissue development, and regulation of gene expression. Mendelian randomisation analysis suggested significant negative causal effects of BMI on FEV1 and on FVC in both the CKB and UKB. Lung function PRSs significantly modified the effect of change in BMI on change in lung function during an average follow-up of 8 years.

CONCLUSION

This large-scale GWAS of lung function identified novel loci and shared genetic aetiology between lung function and obesity. Change in BMI might affect change in lung function differently according to a subject's polygenic background. These findings may open new avenues for the development of molecular-targeted therapies for obesity and lung function improvement.

Blockade of Notch3 inhibits the stem-like property and is associated with ALDH1A1 and CD44 via autophagy in non-small lung cancer

Acquired resistance to standard chemotherapy causes treatment failure in patients with local advanced and advanced non-small lung cancer (NSCLC). Cancer stem cells (CSCs) are a small subpopulation within cancer that is thought to be resistant to conventional chemotherapy. The Notch pathway is one of the most intensively studied for putative therapeutic targets of CSCs in solid tumors. In our study, suppression of Notch3 decreased colony and sphere formation of stem-like property in lung cancer cells. In addition, Notch3 expression was demonstrated to be upregulated in the patients with chemoresistance and related to poor prognosis of NSCLC patients. Our results also showed that CSC markers ALDH1A1 and CD44 were highly expressed in NSCLC patients with chemoresistance and these two markers were positively correlated with Notch3 expression in lung cancer specimens from TCGA database. Furthermore, the lung cancer cells with drug resistance were shown to be associated with activation of autophagy. All the data support a crucial role of Notch3 in the increase of stem-like property in NSCLC cells that might be associated with upregulation of ALDH1A1 and CD44 and activation of autophagy.

Self-organization of firing activities in monkey's motor cortex: trajectory computation from spike signals

The population vector method has been developed to combine the simultaneous direction-related activities of a population of motor cortical neurons to predict the trajectory of the arm movement. In this article, we consider a self-organizing model of a neural representation of the arm trajectory based on neuronal discharge rates. As self-organizing feature map (SOFM) is used to select the optimal set of weights in the model to determine the contribution of an individual neuron to an overall movement representation. The correspondence between movement directions and discharge patterns of the motor cortical neurons is established in the output map. The topology-preserving property of the SOFM is used to analyze the recorded data of a behaving monkey. The data used in this analysis were taken while the monkey was tracing spirals and doing center-->out movements. The arm trajectory could be well predicted using such a statistical model based on the motor cortex neuronal firing information. The SOFM method is compared with the population vector method, which extracts information related to trajectory by assuming that each cell has a fixed preferred direction during the task. This implies that these cells are acting along lines labeled only for direction. However, extradirectional information is carried in these cell responses. The SOFM has the capability of extracting not only direction-related information but also other parameters that are consistently represented in the activity of the recorded population of cells.

Relationship of dietary lysine level to the concentration of all essential amino acids in broiler diets

A study was conducted to evaluate the relationship of dietary Lys and other essential amino acids (EAA) in diets for broilers. Diets were formulated based upon NRC (1994) recommendations. Within each age period, diets contained NRC recommended levels of Lys with other EAA at 100, 110, 120, or 130% of NRC. The diets were then supplemented with 0.1, 0.2, or 0.3% additional Lys, resulting in a 4 x 4 factorial arrangement with four levels of Lys (NRC, + 0.1%, + 0.2%, and + 0.3% Lys) and four levels of other EAA (100, 110, 120, and 130% of NRC). Each of the 16 treatments was fed to six replicate pens of 25 male broilers of a commercial strain. At 56 d, five birds per pen were processed to determine dressing percentage and carcass yield. There were no significant interactions between level of Lys and levels of other EAA for live performance or carcass characteristics. The BW was significantly increased at 21 and 42 d by addition of + 0.1% Lys above NRC but not at 56 d. There was no significant effect of other EAA on BW at any age. The effects of Lys on feed conversion were varied. At 21 and 42 d, addition of 0.1% Lys to diets containing the NRC Lys level significantly improved feed conversion; response to 0.2 or 0.3% Lys were varied. No significant effects of Lys on feed conversion were observed at 56 d. Increasing the level of EAA resulted in significant improvements in feed conversion at 21, 42, and 56 d, generally following a linear trend. Dietary Lys levels had no significant effects on dressing percentage, breast meat yield, or abdominal fat content. The level of other EAA significantly influenced dressed yield but had no significant influence on carcass yield. These results indicate that NRC (1994) levels of Lys and other EAA are adequate for optimum performance of male broilers processed at 56 d but may be less than adequate at younger ages.

Genomic sequencing and editing revealed the GRM8 signaling pathway as potential therapeutic targets of squamous cell lung cancer

The study sought to explore novel genetic aberration driving squamous cell lung carcinoma (LUSC). The whole exome (WES), whole genome (WGS) and target region (TS) sequencings and CRISPR-Cas9 genome editing techniques were integrated to explore and validate novel targeting candidates from LUSC primary tumors and corresponding patient-derived xenografts (PDXs). Seven genes (FGFR2, GRM1,PIK3CG, PIK3CA,ZFHX4, CSMD3, GRM8) with high frequencies of both single nucleotide variants (SNVs) and copy number variants (CNVs), and two genes (CLDN1 and RIT1) only with CNVs were identified by bioinformatics analysis. The functions of these candidates were validated through CRISPR-Cas9 system in primary PDX cells. Furthermore, we focused on the genetic and functional analysis of Metabotropic glutamate receptor 8 (GRM8), whose transcriptional activation was elucidated to promote the survival of LUSC tumor cell through inhibiting cAMP pathway and activating MAPK pathway. The SNV identified in GRM8, A112G, activated downstream signaling pathway and induced cell proliferation, which could be reversed by cAMP stimulator and MEK inhibitor. In conclusion, the components of GRM8 signaling pathway could serve as potential targets of squamous cell lung cancer carrying GRM8 activating variants.

Dynamic topology representing networks

In the present paper, we propose a new algorithm, namely the Dynamic Topology Representing Networks (DTRN) for learning both topology and clustering information from input data. In contrast to other models with adaptive architecture of this kind, the DTRN algorithm adaptively grows the number of output nodes by applying a vigilance test. The clustering procedure is based on a winner-take-quota learning strategy in conjunction with an annealing process in order to minimize the associated mean square error. A competitive Hebbian rule is applied to learn the global topology information concurrently with the clustering process. The topology information learned is also utilized for dynamically deleting the nodes and for the annealing process. Properties of the DTRN algorithm will be discussed. Extensive simulations will be provided to characterize the effectiveness of the new algorithm in topology preserving, learning speed, and classification tasks as compared to other algorithms of the same nature.

ERK MAP kinase activation is required for acetylcholine receptor inducing activity-induced increase in all five acetylcholine receptor subunit mRNAs as well as synapse-specific expression of acetylcholine receptor epsilon-transgene

The AChR is a pentamer of four different subunits in a stoichiometry of alpha2betagammadelta in embryonic and alpha2betaepsilondelta in adult animals. Transcription of AChR subunit genes is most active in synaptic nuclei in adult skeletal muscle cells, and is regulated by neural factors such as ARIA. We report here that ARIA up-regulated specifically the expression of all five AChR subunits in C2C12 cells. The mRNA level of erbB2, erbB3, rapsyn, MuSK, SHP-2 and beta-actin remained unchanged in response to ARIA stimulation in C2C12 cells. The ARIA-induced increase in AChR subunit expression in C2C12 cells was inhibited by the erbB kinase inhibitor tyrphostin AG1478 and the MEK inhibitor PD98059, but not by the PI3 kinase inhibitor wortmannin, suggesting an important role of the erbB protein tyrosine kinases and MAP kinase in the regulation of the expression of the five different AChR subunits. To determine the signaling pathways in vivo, we studied the expression of reporter genes driven by the epsilon-promoter in injected muscles. The in vivo expression of the epsilon-transgene was inhibited by co-expression of dominant negative mutants of key components in the MAP kinase pathway including ras, raf and MEK, but not the dominant negative mutant of PI3 kinase. These results suggest that ERK MAP kinase activation is required for ARIA-induced increase in all five AChR subunit mRNAs as well as synapse-specific expression of AChR epsilon-transgene.

Shisa3 brakes resistance to EGFR-TKIs in lung adenocarcinoma by suppressing cancer stem cell properties

Background

Although EGFR tyrosine kinase inhibitors (EGFR-TKIs) are beneficial to lung adenocarcinoma patients with sensitive EGFR mutations, resistance to these inhibitors induces a cancer stem cell (CSC) phenotype. Here, we clarify the function and molecular mechanism of shisa3 as a suppressor that can reverse EGFR-TKI resistance and inhibit CSC properties.

Methods

The suppresser genes involved in EGFR-TKI resistance were identified and validated by transcriptome sequencing, quantitative real-time PCR (qRT-PCR) and immunohistochemistry. Biological function analyses, cell half maximal inhibitory concentration (IC50), self-renewal, and migration and invasion capacities, were detected by CCK8, sphere formation and Transwell assays. Tumorigenesis and therapeutic effects were investigated in nonobese diabetic/severe combined immunodeficiency (nod-scid) mice. The underlying mechanisms were explored by Western blot and immunoprecipitation analyses.

Results

We found that low expression of shisa3 was related to EGFR-TKI resistance in lung adenocarcinoma patients. Ectopic overexpression of shisa3 inhibited CSC properties and the cell cycle in the lung adenocarcinoma cells resistant to gefitinib/osimertinib. In contrast, suppression of shisa3 promoted CSC phenotypes and the cell cycle in the cells sensitive to EGFR-TKIs. For TKI-resistant PC9/ER tumors in nod-scid mice, overexpressed shisa3 had a significant inhibitory effect. In addition, we verified that shisa3 inhibited EGFR-TKI resistance by interacting with FGFR1/3 to regulate AKT/mTOR signaling. Furthermore, combinational administration of inhibitors of FGFR/AKT/mTOR and cell cycle signaling could overcome EGFR-TKI resistance associated with shisa3-mediated CSC capacities in vivo.

Conclusion

Taken together, shisa3 was identified as a brake to EGFR-TKI resistance and CSC characteristics, probably through the FGFR/AKT/mTOR and cell cycle pathways, indicating that shisa3 and concomitant inhibition of its regulated signaling may be a promising therapeutic strategy for reversing EGFR-TKI resistance.

The effects of x-ray radiation on the eye development of zebrafish

The toxic effects of x-ray radiation on eye development was measured using zebrafish as a model organism. Zebrafish embryos at 8 h post-fertilization (hpf) were irradiated using X-rays at doses of 1, 2, 4, and 8 Gy. At 24 and 48 hpf, x-ray radiation induced a significant increase in reactive oxygen species (ROS) content and cell apoptotic signals. Both of these increases were dose dependent and there were significant positive relationships between them at 24 hpf. At 48 and 72 hpf, the increase of ROS concentration can be eliminated by increasing activities of superoxide dismutase and catalase. Although the ROS generated by x-ray radiation caused a significant increase in cell apoptosis at 24 and 48 hpf, the cellular layers of the retina and lens formation in the irradiated groups were not significantly disrupted at 144 hpf compared with the control group, with the exception of a heterogeneous distribution of the cells in inner nuclear cell layer and a significant decrease in the diameters of whole eyes after 8 Gy irradiation. X-Ray radiation at later stages of gastrulation may not cause distinct optic complications; however, there is still a risk of microophthalmia at high doses of irradiation.

Neuregulin-increased expression of acetylcholine receptor epsilon-subunit gene requires ErbB interaction with Shc

Selective transcription of acetylcholine receptor (AChR) subunit genes by neuregulin is one of the mechanisms involved in the synaptic localization of AChRs to the neuromuscular junction. Neuregulin stimulates ErbB receptor tyrosine kinases and subsequently activates the Ras/ERK pathway, which is required for neuregulin-mediated induction of AChR subunit genes in muscle cells and synapse-specific expression in vivo. Here we investigated the neuregulin transduction mechanism that leads to ERK activation after ErbB receptor tyrosine phosphorylation. Neuregulin increases the association of the adaptor proteins Grb2 and Shc with both ErbB2 and ErbB3 in C2C12 muscle cells. Dephosphorylation of the tyrosine-phosphorylated ErbB proteins abolished their association with both Grb2 and Shc, suggesting a tyrosine phosphorylation-dependent interaction. The interaction of Shc with the ErbB receptors is mediated by Shc's phosphotyrosine-binding domain. In addition, neuregulin increased tyrosine phosphorylation of Shc. Mutagenesis approaches demonstrated that tyrosine phosphorylation of Shc is required for neuregulin induction of AChR subunit gene expression. Taken together, these data indicate that the interaction of ErbB receptors with Grb2 alone is insufficient for neuregulin-activated transcription, but that ErbB receptor signaling via Shc is necessary and important.

Identification of an element required for acetylcholine receptor-inducing activity (ARIA)-induced expression of the acetylcholine receptor epsilon subunit gene

Acetylcholine Receptor (AChR)-inducing activity (ARIA) is believed to be the trophic factor utilized by motoneurons to stimulate AChR synthesis in the subsynaptic area. Among the four AChR subunit genes, the epsilon subunit gene is strictly expressed in nuclei localized to the synaptic region of the muscle. To understand mechanisms of the regulation of synapse-specific transcription, we studied the promoter activity of the 5'-flanking region of the AChR epsilon subunit gene in response to ARIA. Transgenes containing the wild type or mutant 5'-flanking regions upstream of a luciferase gene were transfected in C2C12 muscle cells. The promoter activity of these transgenes was determined by assaying activity of expressed luciferase. Analyzing a combination of 5' deletion and site-directed mutants, we identified a 10-nucleotide element (position -55/-46), which was crucial for ARIA-induced expression from the epsilon subunit promoter. This element was named ARE for ARIA-responsive element. Mutation of ARE greatly diminished ARIA-induced transgene expression and deletion of ARE abolished completely the ARIA response. Electrophoretic mobility shift analyses revealed a DNA binding activity in muscle nuclear extract that interacted with ARE. Such interaction was enhanced by ARIA stimulation of muscle cells and appeared to be dependent on nuclear protein phosphorylation.