Epigenetic Regulation of Cardiomyocyte Maturation by Arginine Methyltransferase CARM1

BACKGROUND

During the neonatal stage, the cardiomyocyte undergoes a constellation of molecular, cytoarchitectural, and functional changes known collectively as cardiomyocyte maturation to increase myocardial contractility and cardiac output. Despite the importance of cardiomyocyte maturation, the molecular mechanisms governing this critical process remain largely unexplored.

METHODS

We leveraged an in vivo mosaic knockout system to characterize the role of Carm1, the founding member of protein arginine methyltransferase, in cardiomyocyte maturation. Using a battery of assays, including immunohistochemistry, immuno-electron microscopy imaging, and action potential recording, we assessed the effect of loss of Carm1 function on cardiomyocyte cell growth, myofibril expansion, T-tubule formation, and electrophysiological maturation. Genome-wide transcriptome profiling, H3R17me2a chromatin immunoprecipitation followed by sequencing, and assay for transposase-accessible chromatin with high-throughput sequencing were used to investigate the mechanisms by which CARM1 (coactivator-associated arginine methyltransferase 1) regulates cardiomyocyte maturation. Finally, we interrogated the human syntenic region to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks for single-nucleotide polymorphisms associated with human heart diseases.

RESULTS

We report that mosaic ablation of Carm1 disrupts multiple aspects of cardiomyocyte maturation cell autonomously, leading to reduced cardiomyocyte size and sarcomere thickness, severe loss and disorganization of T tubules, and compromised electrophysiological maturation. Genomics study demonstrates that CARM1 directly activates genes that underlie cardiomyocyte cytoarchitectural and electrophysiological maturation. Moreover, our study reveals significant enrichment of human heart disease-associated single-nucleotide polymorphisms in the human genomic region syntenic to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks.

CONCLUSIONS

This study establishes a critical and multifaceted role for CARM1 in regulating cardiomyocyte maturation and demonstrates that deregulation of CARM1-dependent cardiomyocyte maturation gene expression may contribute to human heart diseases.

Cholecystokinin-A signaling regulates automaticity of pacemaker cardiomyocytes

Aims: The behavior of pacemaker cardiomyocytes (PCs) in the sinoatrial node (SAN) is modulated by neurohormonal and paracrine factors, many of which signal through G-protein coupled receptors (GPCRs). The aims of the present study are to catalog GPCRs that are differentially expressed in the mammalian SAN and to define the acute physiological consequences of activating the cholecystokinin-A signaling system in isolated PCs. Methods and results: Using bulk and single cell RNA sequencing datasets, we identify a set of GPCRs that are differentially expressed between SAN and right atrial tissue, including several whose roles in PCs and in the SAN have not been thoroughly characterized. Focusing on one such GPCR, Cholecystokinin-A receptor (CCKAR), we demonstrate expression of Cckar mRNA specifically in mouse PCs, and further demonstrate that subsets of SAN fibroblasts and neurons within the cardiac intrinsic nervous system express cholecystokinin, the ligand for CCKAR. Using mouse models, we find that while baseline SAN function is not dramatically affected by loss of CCKAR, the firing rate of individual PCs is slowed by exposure to sulfated cholecystokinin-8 (sCCK-8), the high affinity ligand for CCKAR. The effect of sCCK-8 on firing rate is mediated by reduction in the rate of spontaneous phase 4 depolarization of PCs and is mitigated by activation of beta-adrenergic signaling. Conclusion: (1) PCs express many GPCRs whose specific roles in SAN function have not been characterized, (2) Activation of the cholecystokinin-A signaling pathway regulates PC automaticity.

Cholecystokinin-A Signaling Regulates Automaticity of Pacemaker Cardiomyocytes

Aims

The behavior of pacemaker cardiomyocytes (PCs) in the sinoatrial node (SAN) is modulated by neurohormonal and paracrine factors, many of which signal through G-protein coupled receptors (GPCRs). The aims of the present study are to catalog GPCRs that are differentially expressed in the mammalian SAN and to define the acute physiological consequences of activating the cholecystokinin-A signaling system in isolated PCs.

Methods and Results

Using bulk and single cell RNA sequencing datasets, we identify a set of GPCRs that are differentially expressed between SAN and right atrial tissue, including several whose roles in PCs and in the SAN have not been thoroughly characterized. Focusing on one such GPCR, Cholecystokinin-A receptor (CCK A R), we demonstrate expression of Cckar mRNA specifically in mouse PCs, and further demonstrate that subsets of SAN fibroblasts and neurons within the cardiac intrinsic nervous system express cholecystokinin, the ligand for CCK A R. Using mouse models, we find that while baseline SAN function is not dramatically affected by loss of CCK A R, the firing rate of individual PCs is slowed by exposure to sulfated cholecystokinin-8 (sCCK-8), the high affinity ligand for CCK A R. The effect of sCCK-8 on firing rate is mediated by reduction in the rate of spontaneous phase 4 depolarization of PCs and is mitigated by activation of beta-adrenergic signaling.

Conclusions

(1) PCs express many GPCRs whose specific roles in SAN function have not been characterized, (2) Activation of the the cholecystokinin-A signaling pathway regulates PC automaticity.

Transcription Factor GATA4 Regulates Cell Type-Specific Splicing Through Direct Interaction With RNA in Human Induced Pluripotent Stem Cell-Derived Cardiac Progenitors

BACKGROUND

GATA4 (GATA-binding protein 4), a zinc finger-containing, DNA-binding transcription factor, is essential for normal cardiac development and homeostasis in mice and humans, and mutations in this gene have been reported in human heart defects. Defects in alternative splicing are associated with many heart diseases, yet relatively little is known about how cell type- or cell state-specific alternative splicing is achieved in the heart. Here, we show that GATA4 regulates cell type-specific splicing through direct interaction with RNA and the spliceosome in human induced pluripotent stem cell-derived cardiac progenitors.

METHODS

We leveraged a combination of unbiased approaches including affinity purification of GATA4 and mass spectrometry, enhanced cross-linking with immunoprecipitation, electrophoretic mobility shift assays, in vitro splicing assays, and unbiased transcriptomic analysis to uncover GATA4's novel function as a splicing regulator in human induced pluripotent stem cell-derived cardiac progenitors.

RESULTS

We found that GATA4 interacts with many members of the spliceosome complex in human induced pluripotent stem cell-derived cardiac progenitors. Enhanced cross-linking with immunoprecipitation demonstrated that GATA4 also directly binds to a large number of mRNAs through defined RNA motifs in a sequence-specific manner. In vitro splicing assays indicated that GATA4 regulates alternative splicing through direct RNA binding, resulting in functionally distinct protein products. Correspondingly, knockdown of GATA4 in human induced pluripotent stem cell-derived cardiac progenitors resulted in differential alternative splicing of genes involved in cytoskeleton organization and calcium ion import, with functional consequences associated with the protein isoforms.

CONCLUSIONS

This study shows that in addition to its well described transcriptional function, GATA4 interacts with members of the spliceosome complex and regulates cell type-specific alternative splicing via sequence-specific interactions with RNA. Several genes that have splicing regulated by GATA4 have functional consequences and many are associated with dilated cardiomyopathy, suggesting a novel role for GATA4 in achieving the necessary cardiac proteome in normal and stress-responsive conditions.

ATAC-Seq Reveals an Isl1 Enhancer That Regulates Sinoatrial Node Development and Function

RATIONALE

Cardiac pacemaker cells (PCs) in the sinoatrial node (SAN) have a distinct gene expression program that allows them to fire automatically and initiate the heartbeat. Although critical SAN transcription factors, including Isl1 (Islet-1), Tbx3 (T-box transcription factor 3), and Shox2 (short-stature homeobox protein 2), have been identified, the cis-regulatory architecture that governs PC-specific gene expression is not understood, and discrete enhancers required for gene regulation in the SAN have not been identified.

OBJECTIVE

To define the epigenetic profile of PCs using comparative ATAC-seq (assay for transposase-accessible chromatin with sequencing) and to identify novel enhancers involved in SAN gene regulation, development, and function.

METHODS AND RESULTS

We used ATAC-seq on sorted neonatal mouse SAN to compare regions of accessible chromatin in PCs and right atrial cardiomyocytes. PC-enriched assay for transposase-accessible chromatin peaks, representing candidate SAN regulatory elements, were located near established SAN genes and were enriched for distinct sets of TF (transcription factor) binding sites. Among several novel SAN enhancers that were experimentally validated using transgenic mice, we identified a 2.9-kb regulatory element at the Isl1 locus that was active specifically in the cardiac inflow at embryonic day 8.5 and throughout later SAN development and maturation. Deletion of this enhancer from the genome of mice resulted in SAN hypoplasia and sinus arrhythmias. The mouse SAN enhancer also directed reporter activity to the inflow tract in developing zebrafish hearts, demonstrating deep conservation of its upstream regulatory network. Finally, single nucleotide polymorphisms in the human genome that occur near the region syntenic to the mouse enhancer exhibit significant associations with resting heart rate in human populations.

CONCLUSIONS

(1) PCs have distinct regions of accessible chromatin that correlate with their gene expression profile and contain novel SAN enhancers, (2) cis-regulation of Isl1 specifically in the SAN depends upon a conserved SAN enhancer that regulates PC development and SAN function, and (3) a corresponding human ISL1 enhancer may regulate human SAN function.

Microwave-Water Bath Hybrid Warming for Frozen Cryoprotectant Solution Using a Helical Antenna

BACKGROUND

Successful cryopreservation of organs and/or tissues of large dimension is challenging due to damages by solute concentration and thermal stress caused by crystallization during cooling and devitrification/recrystallization during rewarming. The key to reduce thermal stresses in cryopreserved biomaterials during rewarming is fast and uniform heating.

OBJECTIVE

To explore a hybrid warming process using two heat sources (microwave and water bath) simultaneously to achieve faster and more uniform heating.

MATERIALS AND METHODS

Rewarming of frozen cryoprotectants (CPA) using microwave and 37ºC water bath at the same time was experimentally studied. A helical antenna was installed at the center of a 1.8 mL cryovial. Microwave (2.4 GHz) was generated, amplified and transported to the helical antenna through the matched coaxial cables. Frozen CPA solution in the cryovial at an initial temperature of -196ºC was rewarmed by microwave and water bath. The temperature of two selected points in the sample with the maximum temperature difference was measured by thermocouples during rewarming.

RESULTS

During rewarming of the frozen sample in 37ºC water bath without microwave, the warming rate was 70.2ºC min-1 with the maximum temperature gradient of 1.07ºC mm^-1 in the sample. With microwave added to form a hybrid warming process, the warming rate was increased to be 100.5ºC min^-1 with a smaller temperature gradient of 0.68ºC mm^-1.

CONCLUSION

The study indicated that warming rate and temperature uniformity increased with the microwave-water bath hybrid heating process.

Mechanistic analysis and experimental verification of bicarbonate-controlled enteric coat dissolution: Potential in vivo implications

Enteric coatings have shown in vivo dissolution rates that are poorly predicted by traditional in vitro tests, with the in vivo dissolution being considerably slower than in vitro. To provide a more mechanistic understanding of this, the dependence of the release properties of various enteric-coated (EC) products on bulk pH and bicarbonate molarity was investigated. It was found that, at presumably in vivo-relevant values, the bicarbonate molarity is a more significant determinant of the dissolution profile than the bulk pH. The findings also indicate that this steep relationship between the dissolution of enteric coatings and bicarbonate molarity limits those coatings' performance in vivo. This is attributed to the relatively low bicarbonate molarities in human intestinal fluids. Further, the hydration and dehydrations kinetics of carbonic acid and carbon dioxide are not sufficiently rapid to reach equilibrium in the diffusion layer surrounding a dissolving ionizable solid. This results in the effective pKa of bicarbonate in the diffusion layer being lower than that determined potentiometrically at equilibrium in the bulk surrounding fluid. These results demonstrate the importance of thoroughly investigating the intestinal bicarbonate concentrations and using bicarbonate buffers or properly designed surrogates (if possible) when evaluating enteric drug products during product development and quality control.

Irf8 regulates the progression of myeloproliferative neoplasm-like syndrome via Mertk signaling in zebrafish

Interferon regulatory factor (IRF)-8 is a critical transcription factor involved in the pathogenesis of myeloid neoplasia. However, the underlying mechanisms in vivo are not well known. Investigation of irf8-mutant zebrafish in this study indicated that Irf8 is evolutionarily conserved as an essential neoplastic suppressor through tight control of the proliferation and longevity of myeloid cells. Surviving irf8 mutants quickly developed a myeloproliferative neoplasm (MPN)-like disease with enhanced output of the myeloid precursors, which recurred after transplantation. Multiple molecules presented notable alteration and Mertk signaling was aberrantly activated in the hematopoietic cells in irf8 mutants. Transgenic mertk overexpression in Tg(coro1a:mertk) zebrafish recapitulated the myeloid neoplasia-like syndrome in irf8 mutants. Moreover, functional interference with Mertk, via morpholino knockdown or genetic disruption, attenuated the myeloid expansion phenotype caused by Irf8 deficiency. Therefore, Mertk signaling is a critical downstream player in the Irf8-mediated regulation of the progression of myeloid neoplasia. Our study extends the understanding of the mechanisms underlying leukemogenesis.

A Sarcoplasmic Reticulum Localized Protein Phosphatase Regulates Phospholamban Phosphorylation and Promotes Ischemia Reperfusion Injury in the Heart

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PP2Ce is Ser-Thr phosphatase specifically localized on SR and expressed in cardiomyocytes.

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PP2Ce has specific phosphatase activity to dephosphorylate Thr-17 site of phospholamban.

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PP2Ce expression is induced upon pathological stress, including beta-AR stimulation and ROS.

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PP2Ce induction suppresses cardiomyocyte calcium cycling, reduces beta-AR-induced contractility, and promotes oxidative ischemia/reperfusion injury.

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PP2Ce is a new molecular component of stress-mediated cardiomyocyte calcium regulation.

Phospholamban (PLN) is a key regulator of sarcolemma calcium uptake in cardiomyocyte; its inhibitory activity to sarcolemma-endoplasmic reticulum calcium ATPase is regulated by phosphorylation. PLN hypophosphorylation is a common molecular feature in the failing heart. The current study provided evidence at the molecular, cellular, and whole-heart levels to implicate a sarcolemma membrane-targeted protein phosphatase, PP2Ce, as a specific and potent PLN phosphatase. PP2Ce expression was elevated in failing human heart and induced acutely at protein level by β-adrenergic stimulation or oxidative stress in cardiomyocytes. PP2Ce expression in mouse heart blunted β-adrenergic response and exacerbated ischemia/reperfusion injury. Therefore, PP2Ce is a new regulator for cardiac function and pathogenesis.

Creation of zebularine-resistant human cytidine deaminase mutants to enhance the chemoprotection of hematopoietic stem cells

Human cytidine deaminase (hCDA) is a biomedically important enzyme able to inactivate cytidine nucleoside analogs such as the antileukemic agent cytosine arabinoside (AraC) and thereby limit antineoplastic efficacy. Potent inhibitors of hCDA have been developed, e.g. zebularine, that when administered in combination with AraC enhance antineoplastic activity. Tandem hematopoietic stem cell (HSC) transplantation and combination chemotherapy (zebularine and AraC) could exhibit robust antineoplastic potency, but AraC-based chemotherapy regimens lead to pronounced myelosuppression due to relatively low hCDA activity in HSCs, and this approach could exacerbate this effect. To circumvent the pronounced myelosuppression of zebularine and AraC combination therapy while maintaining antineoplastic potency, zebularine-resistant hCDA variants could be used to gene-modify HSCs prior to transplantation. To achieve this, our approach was to isolate hCDA variants through random mutagenesis in conjunction with selection for hCDA activity and resistance to zebularine in an Escherichia coli genetic complementation system. Here, we report the identification of nine novel variants from a pool of 1.6 × 106 transformants that conferred significant zebularine resistance relative to wild-type hCDA2. Several variants revealed significantly higher Ki values toward zebularine when compared with wild-type hCDA values and, as such, are candidates for further exploration for gene-modified HSC transplantation approaches.

mTOR pathway is involved in ADP-evoked astrocyte activation and ATP release in the spinal dorsal horn in a rat neuropathic pain model

BACKGROUND

ATP/ADP-evoked spinal astrocyte activation plays a vital role in the development of neuropathic pain. We aim to investigate the role of mammalian target of rapamycin (mTOR) pathway on the spinal astrocyte activation in the neuropathic pain development in rats.

METHODS

Sprague Dawley (SD) rats were subjected to chronic constriction of the sciatic nerve (CCI). Rapamycin or ADP was intrathecally injected daily to explore their effects on spinal astrocyte activation and pain development. Expression of glial fibrillary acidic protein (GFAP) and mTOR in the spinal dorsal horn was assessed by immunohistochemistry. Von Frey hairs and Hargreaves paw withdrawal test were conducted to evaluate mechanical allodynia and thermal sensitivity, respectively. Firefly luciferase ATP assay was used to assess the change of ATP level in cerebrospinal fluid (CSF) and medium of cultured astrocytes.

RESULTS

GFAP expression was enhanced in the ipsilateral spinal dorsal horn from day 3 after surgery. GFAP and mTOR expression in the rat spinal dorsal horn on post-surgical day 14 was enhanced by daily intrathecal injection of ADP, which was inhibited by rapamycin. Rapamycin decreased lower mechanical pain threshold and the thermal withdrawal latency. Intrathecal injection of ADP enhanced the ATP release, which was partially inhibited by rapamycin. Study of cultured astrocytes indicated that ATP could be released from astrocytes.

CONCLUSION

Our data demonstrated that ADP enhanced neuropathic pain in CCI rats, which was inhibited by rapamycin. This study indicates that targeting mTOR pathway could serve as a novel therapeutic strategy in neuropathic pain management.

Modified Sauvé-Kapandji procedure for restoration of forearm rotation in devascularized hands

INTRODUCTION

The purpose of this study is to evaluate the clinical outcomes in patients with forearm rotation limitation after successful wrist-level revascularization who underwent a modified Sauvé-Kapandji (S-K) procedure.

METHODS

This was a retrospective review of the clinical records of nine patients (three women, six men) after successful wrist-level revascularization who underwent late restoration of forearm rotation. All patients were evaluated using a Mayo Modified Wrist Score. The mean patient age was 35 (range 19-45) years. Mean time to reconstruction was 2.5 (range 0.5-4) years.

RESULTS

Mean postoperative pronation was 74°; mean postoperative supination was 80°. Overall results were excellent/good in seven patients, fair in one, and poor in one. No bone bridge was formed between the pseudarthrosis in any patient. Two patients had neurapraxia. Moderate pain and snapping occurred in one patient during movement at the ulnar amputation site.

CONCLUSION

This modification of the S-K procedure can restore rotation of the forearm after hand revascularization; as such, it provides an alternative salvage procedure.

Abstract 233: Isoproterenol-induced Cardiac Hypertrophy And Failure In Mice: Gene Network Modeling

Heart failure is highly heterogeneous and as a result, relatively few insights into the pathways and drivers of heart failure have been identified using system-wide methods such as genome-wide association studies (GWAS). We have developed a resource, the Hybrid Mouse Diversity Panel (HMDP) for high resolution GWAS and systems genetics in mice. Eight week old female mice from 93 unique inbred strains of the HMDP were given 20 μg/g/day of isoproterenol through an abdominally implanted Alzet micropump. Three weeks post-implantation, all mice were sacrificed, along with age-matched controls. The mice exhibited widely varying degrees of hypertrophy and heart functioning. A portion of the left ventricle was processed and arrayed on an Illumina Mouse Ref 8.0 platform.

We used Maximal Information Component Analysis, a novel method of network construction which allows for non-linear relationships between genes as well as non-binary partitioning of genes into sub-networks to subdivide the expression data into a series of modules. In order to identify modules which may contribute to Isoproterenol-induced hypertrophy and failure, we examined the correlation of each module to clinically relevant cardiac traits traits such as organ weights and echocardiographic parameters.

We identified several modules with strong correlations to multiple heart failure-related clinical traits, including one module of 41 genes which contained several genes of interest, including Lgals3, a diagnostic marker for heart failure. Utilizing eQTL hotspot analysis, we have identified a locus which is involved in the regulation of this module. A gene within this locus, Magi2, regulates the turnover of the β-adrenergic receptor and represents a likely candidate for the response to isoproterenol.

Pulsed ultrasound modulated optical tomography utilizing the harmonic response of lock-in detection

Ultrasound modulated optical tomography (USMOT) can image the optical properties of a scattering medium at a spatial resolution approaching that of ultrasound (US). A lock-in parallel speckle detection technique is proposed to detect pulsed US modulated light using a multipixel detector. The frequency components of the pass band match those of the US pulse train and provide efficient detection. The modulation depth is extracted by taking the difference between a pair of speckle patterns modulated by a pair of phase-inversed US bursts. Modification to pulse inversion mode enables the second harmonic US modulation due to nonlinear US propagation to be detected.

Enzymes to die for: exploiting nucleotide metabolizing enzymes for cancer gene therapy

Suicide gene therapy is an attractive strategy to selectively destroy cancer cells while minimizing unnecessary toxicity to normal cells. Since this idea was first introduced more than two decades ago, numerous studies have been conducted and significant developments have been made to further its application for mainstream cancer therapy. Major limitations of the suicide gene therapy strategy that have hindered its clinical application include inefficient directed delivery to cancer cells and the poor prodrug activation capacity of suicide enzymes. This review is focused on efforts that have been and are currently being pursued to improve the activity of individual suicide enzymes towards their respective prodrugs with particular attention to the application of nucleotide metabolizing enzymes in suicide cancer gene therapy. A number of protein engineering strategies have been employed and our discussion here will center on the use of mutagenesis approaches to create and evaluate nucleotide metabolizing enzymes with enhanced prodrug activation capacity and increased thermostability. Several of these studies have yielded clinically important enzyme variants that are relevant for cancer gene therapy applications because their utilization can serve to maximize cancer cell killing while minimizing the prodrug dose, thereby limiting undesirable side effects.

Abstract 190: Protein Phosphatase 2Ce Is a Novel Phospholamban Phosphatase that Exacerbates Cell Death and Suppresses Cardiac Contractility

Regulation of sarcoplasmic reticulum (SR) calcium-ATPase (SERCA) activity is critical for calcium homeostasis in cardiomyocytes, and has a major impact on contractility and cellular viability of cardiomyocytes. The key regulators for SERCA activity include protein kinases, cAMP dependent protein kinase A and calcium/calmodulin dependent protein kinase II, and protein phosphatase 1. In this report, we have discovered that protein phosphatase 2Ce (PP2Ce) is a novel serine/threonine protein phosphatase specifically targeted to SR membrane in cardiomyocytes. PP2Ce was detected to interact with phosphlamban in heart. Recombinant PP2Ce protein showed a potent and specific activity towards the calcium/calmodulin dependent protein kinase II dependent phospholamban phosphorylation at threonin 17 site with no significant activity to cAMP dependent protein kinase A dependent phospholamban phosphorylation at serine 16 site. Expression of PP2Ce blunted β-adrenergic stimulated increase of phospholamban phosphorylation without affecting phosphorylation of ryanodine recepter or troponin I. PP2Ce expression reduced β-adrenergic stimulated intracellular calcium transient in isolated adult rabbit ventricular myocytes, and promoted hydrogen peroxide induced cell death in cultured neonatal rat ventricular myocytes. Transgenic mice with cardiac specific expression of PP2Ce showed no significant basal phenotype. However, in isolated perfusion heart preparation, β-adrenergic stimulated contractility was significant reduced in PP2Ce transgenic hearts comparing to wild type controls. Furthermore, we observed significantly larger infarct sizes and more impaired functional recovery following global ischemia/reperfusion injury in the transgenic hearts comparing to wild type controls. Therefore, PP2Ce is a novel component of SR calcium regulatory network that has a potentially important role in cell death regulation and cardiac contractility.

Breaking Barriers to an AIDS Model with Macaque-Tropic HIV-1 Derivatives

The development of an animal model of human immunodeficiency virus type 1 (HIV-1)/AIDS that is suitable for preclinical testing of antiretroviral therapy, vaccines, curative strategies, and studies of pathogenesis has been hampered by the human-specific tropism of HIV-1. Although simian immunodeficiency virus (SIV) or HIV-1/SIV chimeric viruses (SHIVs)-rhesus macaque models are excellent surrogates for AIDS research, the genetic differences between SIV or SHIV and HIV-1 limit their utility as model systems. The identification of innate retro viral restriction factors has increased our understanding about blockades to HIV-1 replication in macaques and provided a guide for the construction of macaque-tropic HIV-1 clones. However, while these viruses replicate in macaque cells in vitro, they are easily controlled and have not caused AIDS in host animals, indicating that we may not fully understand the restrictive barriers of innate immunity. In this review, we discuss recent findings regarding HIV-1 restriction factors, particularly as they apply to cross-species transmission of primate lentiviruses and the development of a macaque model of HIV-1/AIDS.

Effects of acoustic stimuli on neuronal activity in the auditory cortex of the rat

Spontaneous activity of cortical neurons exhibits alternative fluctuations of membrane potential consisting of phased depolarization called "up-state" and persistent hyperpolarization called "down-state" during slow wave sleep and anesthesia. Here, we examined the effects of sound stimuli (noise bursts) on neuronal activity by intracellular recording in vivo from the rat auditory cortex (AC). Noise bursts increased the average time in the up-state by 0.81+/-0.65 s (range, 0.27-1.74 s) related to a 10 s recording duration. The rise times of the spontaneous up-events averaged 69.41+/-18.04 ms (range, 40.10-119.21 ms), while those of the sound-evoked up-events were significantly shorter (p<0.001) averaging only 22.54+/-8.81 ms (range, 9.31-45.74 ms). Sound stimulation did not influence ongoing spontaneous up-events. Our data suggest that a sound stimulus does not interfere with ongoing spontaneous neuronal activity in auditory cortex but can evoke new depolarizations in addition to the spontaneous ones.

Myc controls transcriptional regulation of cardiac metabolism and mitochondrial biogenesis in response to pathological stress in mice

In the adult heart, regulation of fatty acid oxidation and mitochondrial genes is controlled by the PPARgamma coactivator-1 (PGC-1) family of transcriptional coactivators. However, in response to pathological stressors such as hemodynamic load or ischemia, cardiac myocytes downregulate PGC-1 activity and fatty acid oxidation genes in preference for glucose metabolism pathways. Interestingly, despite the reduced PGC-1 activity, these pathological stressors are associated with mitochondrial biogenesis, at least initially. The transcription factors that regulate these changes in the setting of reduced PGC-1 are unknown, but Myc can regulate glucose metabolism and mitochondrial biogenesis during cell proliferation and tumorigenesis in cancer cells. Here we have demonstrated that Myc activation in the myocardium of adult mice increases glucose uptake and utilization, downregulates fatty acid oxidation by reducing PGC-1alpha levels, and induces mitochondrial biogenesis. Inactivation of Myc in the adult myocardium attenuated hypertrophic growth and decreased the expression of glycolytic and mitochondrial biogenesis genes in response to hemodynamic load. Surprisingly, the Myc-orchestrated metabolic alterations were associated with preserved cardiac function and improved recovery from ischemia. Our data suggest that Myc directly regulates glucose metabolism and mitochondrial biogenesis in cardiac myocytes and is an important regulator of energy metabolism in the heart in response to pathologic stress.

Inducible and cardiac specific PTEN inactivation protects ischemia/reperfusion injury

PTEN is a dual lipid and protein phosphatase that antagonizes PI3K as well as other signaling pathways and regulates cellular survival and growth. However, its potential role in cardiac ischemia/reperfusion injury remains unknown. We established a transgenic mouse model with inducible and cardiac specific deletion of Pten gene (Pten(CKO)) in adult heart via tamoxifen dependent Cre-loxP mediated DNA recombination. 3 weeks after tamoxifen induced PTEN inactivation, elevated PI3K activity was observed in the Pten(CKO) hearts as determined from downstream AKT signaling. No significant differences in cardiac function as well as chamber size were observed between Pten(CKO) and Control animals based on echocardiography. In response to 30 min ischemia followed by 120 min reperfusion in Langendorff preparations, Pten(CKO) hearts developed significantly better function recovery than Control animals. At 60 min post reperfusion, the recovery of LVDP reached 77.9% of pre-ischemia basal in Pten(CKO) hearts vs 44.2% of Control (p<0.01). Consistent with the observed functional improvement, TTC staining revealed a significant reduction in infarct size in Pten(CKO) hearts compared with Control (24.2% vs 39.7%, p<0.05). Pten(CKO) hearts had significantly fewer apoptosis positive cardiomyocytes after I/R injury as identified by TUNEL staining. Furthermore, ERK activity and BCL-2 expression were not affected at basal but became significantly higher after ischemia/reperfusion in Pten(CKO) hearts. These data indicate that PTEN may play a role in ischemia/reperfusion injury by inhibiting anti-apoptotic survival signals. Inhibiting PTEN may serve as a potential approach to exert cardiac protection against ischemia reperfusion injury.

Silencing Jnk1 and Jnk2 accelerates basal lipolysis and promotes fatty acid re-esterification in mouse adipocytes

AIMS/HYPOTHESIS

Elevated plasma levels of NEFA impair insulin action. Given the positive linear correlation between NEFA released by adipocytes and plasma NEFA levels, identification of mechanisms controlling adipocyte lipolysis and NEFA release could provide a guide to new therapies for insulin resistance and type 2 diabetes.

METHODS

Short hairpin RNA-mediated gene ablation was used to determine the functions of c-Jun N-terminal kinase (JNK)1 and JNK2 in adipocytes.

RESULTS

Combined JNK1/JNK2 deficiency drastically increased basal glycerol release, whereas individual JNK1- or JNK2-deficiency had no effect, indicating that JNK1/JNK2-deficiency enhances basal lipolysis, whereas the alternate subtype compensates for a single JNK subtype deficiency in the regulation of basal lipolysis. The profoundly increased glycerol release associated with JNK1/JNK2-deficiency was not accompanied by a concomitant increase in NEFA release over time. In addition, JNK1-deficiency, but not JNK2-deficiency, drastically decreased NEFA release as compared with that in JNK-intact cells, a result of increased NEFA re-esterification. In microarray, quantitative RT-PCR and western blotting, JNK1-, JNK2- and JNK1/JNK2-deficiencies selectively upregulated many genes involved in NEFA management, without affecting the expression of genes involved in insulin signalling. Assays using reporter genes driven by peroxisome proliferator-activated receptor gamma (PPAR-gamma)-responsive promoters indicate distinct roles for JNK1 and JNK2 in regulating the transcriptional effects of PPAR-gamma.

CONCLUSIONS/INTERPRETATION

While JNK1 and JNK2 have shared roles in the regulation of basal lipolysis, JNK1 has a more profound role in supporting baseline NEFA release. Inhibition of JNK1 activity in adipocytes has potential therapeutic uses for management of elevated circulating NEFA levels at the onset of insulin resistance.

Giα1-Mediated Cardiac Electrophysiological Remodeling and Arrhythmia in Hypertrophic Cardiomyopathy

BACKGROUND

Cardiac hypertrophy is a major risk factor for arrhythmias and sudden cardiac death. However, the underlying signaling mechanisms involved in the induction of arrhythmia and electrophysiological remodeling in cardiac hypertrophy are unclear.

METHODS AND RESULTS

Using an inducible gene-switch approach, we achieved tissue-specific and temporally regulated induction of a well-established hypertrophic pathway, the Ras-Raf-mitogen-activated protein kinases pathway, in adult mouse heart. On Ras activation, the transgenic animal developed ventricular hypertrophy and arrhythmias. The development of ventricular arrhythmias was temporally correlated with electrophysiological remodeling in isolated ventricular myocytes, including action potential prolongation, increased sodium-calcium exchanger activity, reduced outward potassium currents, sarcoplasmic reticulum Ca2+ defects, and loss of protein kinase A-dependent phospholamban phosphorylation. From genome-wide expression profiling, we discovered a selective induction of G alpha inhibiting subunit 1 (Gi alpha1) expression in the Ras transgenic heart. Treatment of transgenic animals with the Gi/o inhibitor pertussis toxin normalized the phospholamban phosphorylation by protein kinase A, reversed the action potential prolongation, and significantly reduced the frequency of cardiac arrhythmias in Ras transgenic animals.

CONCLUSIONS

These data suggest that selective induction of G alpha inhibiting subunit 1 expression and activity is a novel downstream event in hypertrophic signaling that may be a critical factor leading to cellular electrophysiological remodeling and cardiac arrhythmias in hypertrophic cardiomyopathy.

Response surface methodology for optimizing the fermentation medium of alpha-galactosidase in solid-state fermentation

AIMS

Alpha-galactosidase is applied in food and feed industries for hydrolysing raffinose series oligosaccharides (RO) that are the factors primarily responsible for flatulence upon ingestion of soybean-derived products. The objective of the current work was to develop an optimal culture medium for the production of alpha-galactosidase in solid-state fermentation (SSF) by a mutant strain Aspergillus foetidus.

METHODS AND RESULTS

Response surface methodology (RSM) was applied to evaluate the effects of variables, namely the concentrations of wheat bran, soybean meal, KH(2)PO(4), MnSO(4).H(2)O and CuSO(4).5H(2)O on alpha-galactosidase production in the solid substrate. A fractional factorial design (FFD) was firstly used to isolate the main factors that affected the production of alpha-galactosidase and the central composite experimental design (CCD) was then adopted to derive a statistical model for optimizing the composition of the fermentation medium. The experimental results showed that the optimum fermentation medium for alpha-galactosidase production by Aspergillus foetidus ZU-G1 was composed of 8.2137 g wheat bran, 1.7843 g soybean meal, 0.001 g MnSO(4).H(2)O and 0.001 g CuSO(4).5H(2)O in 10 g dry matter fermentation medium.

CONCLUSIONS

After incubating 96 h in the optimum fermentation medium, alpha-galactosidase activity was predicted to be 2210.76 U g(-1) dry matter in 250 ml shake flask. In the present study, alpha-galactosidase activity reached 2207.19 U g(-1) dry matter.

SIGNIFICANCE AND IMPACT OF THE STUDY

Optimization of the solid substrate was a very important measure to increase enzyme activity and realize industrial production of alpha-galactosidase. The process of alpha-galactosidase production in laboratory scale may have the potential to scale-up.

Studies on a kinetic model for butyric acid bioproduction by Clostridium butyricum

AIMS

This paper discusses the establishment of a kinetic model for cell growth, butyric acid production and substrate consumption of Clostridium butyricum ZJUCB in batch cultivation.

METHODS AND RESULTS

Mathematic simulations were proposed by the logistic equation for the cell growth, the Luedeking-Piret equation for butyric acid production and the Luedeking-Piret-like equation for glucose consumption.

CONCLUSION

We compared the performance of our model against that obtained by the empirically experimental design. The experiment-validated model was found suitable for studying butyric acid fermentation kinetics in a complex dynamic behaviour of C. butyricum, especially for its singular growth phenomenon.

SIGNIFICANCE AND IMPACT OF THE STUDY

The model parameters are estimated from the data fitting and evaluated for simulation of the time courses of the concentrations of cell biomass, butyric acid and glucose and the model appears to fit the experimental data well. The results may be useful for butyric acid production by microbial fermentation.

Molecular and Functional Signature of Heart Hypertrophy During Pregnancy

During pregnancy, the heart develops a reversible physiological hypertrophic growth in response to mechanical stress and increased cardiac output; however, underlying molecular mechanisms remain unknown. Here, we investigated pregnancy-related changes in heart structure, function, and gene expression of known markers of pathological hypertrophy and cell stretching in mice hearts. In late pregnancy, hearts show eccentric hypertrophy, as expected for a response to volume overload, with normal left ventricular diastolic function and a moderate reduction in systolic function. Pregnancy-related physiological heart hypertrophy does not induce expression changes of known markers of pathological hypertrophy like: α- and β-myosin heavy chain, atrial natriuretic factor, phospholamban, and sarcoplasmic reticulum Ca 2+ -ATPase. Instead, it induces the remodeling of Kv4.3 channel and increased c-Src tyrosine kinase activity, a stretch-responsive kinase. Cardiac Kv4.3 channel gene expression was downregulated by ≈3- to 5-fold, both at the mRNA and protein levels, and was paralleled by a reduction in transient outward K + currents, a longer action potential and by prolongation of the QT interval. Downregulation of cardiac Kv4.3 transcripts was mimicked by estrogen treatment in ovariectomized mice, and was prevented by the estrogen receptor antagonist ICI 182,780. c-Src activity increased by ≈2-fold in late pregnancy and after estrogen treatment. We propose that, in addition to mechanical stress, the rise of estrogen toward the end of pregnancy contributes to pregnancy-related heart hypertrophy by increased c-Src activity and that the rise of estrogen is one factor that down regulates cardiac Kv4.3 gene expression providing a molecular correlate for a longer QT interval in pregnancy.

Combination of Targeting Gene-ViroTherapy with 5-FU enhances antitumor efficacy in malignant colorectal carcinoma

To improve the therapeutic effect of ONYX015, an E1B55kD-deleted replication-competent adenovirus, ZD55 was constructed and armed with the therapeutic gene hTRAIL to form ZD55-hTRAIL, which was used for cancer therapy and which we call Targeting Gene-ViroTherapy. In vitro experiments with SW620, HCT116, and HT29 colorectal carcinoma cell lines demonstrated that they were all sensitive to ZD55-hTRAIL, and especially sensitive to ZD55-hTRAIL plus 5-fluorouracil (5-FU) treatment. In the SW620 xenograft tumor model, various treatment groups showed marked differences at week 11, with the tumor volume for the phosphate-buffered saline (PBS) treatment group >1700 mm3, for 5-FU > 1300 mm3, for ONYX015 1051.3 mm3, for ZD55-hTRAIL 600.05 mm3, and for ZD55-hTRAIL plus 5-FU 230.2 mm3. At the end of week 14, tumor-bearing mice in the other groups almost all died, whereas all the mice in the combined treatment group were alive, with one mouse tumor free. By transmission electron microscopy (TEM) assay, most tumor cells treated with ONYX015 or with ZD55-hTRAIL singly or in combination with 5-FU were lysed due to viral propagation. RT-PCR analysis and immunohistochemistry examination revealed that hTRAIL was expressed in ZD55-hTRAIL-treated SW620 tumor tissue. Furthermore, no detectable hepatoxicity was found by serum enzyme level analysis. These results suggest that ZD55-hTRAIL alone or in combination with 5-FU may have potential clinical implications.

[Effects of activin and follistatin on FSH receptor mRNA expression of cultured Shao duck granulosa cells]

The aim of this study was to investigate the action of activin and follistatin either alone or in combination on FSH receptor mRNA expression. The results showed that activin alone increased FSH receptor mRNA level in the presence or absence of FSH in cultured granulosa cells, and the stimulating effect of activin on FSH receptor level was dose-dependent. This effect of activin was inhibited by FSP treatment which alone had no effect on FSH receptor expression. From the results, it can be concluded that activin and follistatin both exert autocrine actions on granulosa cells, and the two factors, possibly by regulating FSH receptor expression, may play important roles in follicular development.

[Expression pattern of mRNA for follistatin and inhibin/activin beta B-subunit during follicular and testicular development in duck]

Follistatin and inhibin/activin were closely related glycoprotein hormones. The quantitative competitive RT-PCR was used to investigate the expression of follistatin and inhibin/activin beta B-subunit mRNA in the developing ovarian follicles, immature and mature testes. The results revealed all samples showed the expression of mRNA for the two proteins, and the expression is more abundantly in the small follicles than in the large preovulatory follicles. Competitive RT-PCR revealed that the expression of follistatin is the highest in small yellow follicles (SYF), the mean relative content for the F1, F2, F3, F4, F5, F6-8, LWF (large white follicle), TI(immature testes), and TM(mature testes) was 0.011 +/- 0.004, 0.019 +/- 0.006, 0.021 +/- 0.009, 0.028 +/- 0.007, 0.075 +/- 0.023, 0.15 +/- 0.072, 0.29 +/- 0.068, 0.037 +/- 0.011, and 0.012 +/- 0.004, respectively, compared to a mean relative content of 1.00 for the SYF. The highest level of inhibin/activin beta B mRNA was also found in the SYF, the mean relative content for the F1, F2, F3, F4, F5, F6-8, LWF, TI, and TM was 0.009 +/- 0.003, 0.013 +/- 0.005, 0.019 +/- 0.007, 0.023 +/- 0.006, 0.29 +/- 0.084, 0.84 +/- 0.093, 0.031 +/- 0.008, 0.38 +/- 0.072, and 0.046 +/- 0.013, respectively, compared to a mean relative content of 1.00 for the SYF. Our data suggested that the expression pattern of mRNA for follistatin and inhibin/activin beta B-subunit was quite similar during follicular and testicular development. The great co-expression of mRNA for the two proteins in small follicles indicated that activin B(beta B-beta B) availability was tightly regulated by follistatin, and the two proteins might both play important roles in early follicular development.

[Studies of genetic diversity of Zhejiang native chicken breeds]

A total of 539 bases of mitochondrial DNA D-loop region of five native chicken breeds of Zhejiang province and the white leghorn chicken (as the control) were sequenced by DNA sequencing technique, and the phylogenetic trees of the chicken breeds were constructed. The results showed that 24 variation sites i.e. 4.45% sequence divergence were detected among the 30 DNA sequences, and the six breeds belonged to two different maternal lineage, one included Xianju chicken and White Leghorn chicken which had the same maternal origin, the other included Lingkun chicken, Baiyiner chicken, Wugu chicken and Xiaoshan chicken which had the same matriarchic ancestor. Among the latter lineage, Lingkun chicken, Baiyiner chicken and Wugu chicken had a closer relationship to each other than to Xiaoshan chicken.

[cDNA cloning and mRNA expression pattern in follicles of the mature inhibin alpha subunit from Xianju chicken]

The mature region of Xianju chicken inhibin alpha-subunit was amplified from the total RNA of follicle granulosa cells by RT-PCR using the primer pair designed according to the reported cDNA sequence of chicken inhibin alpha-subunit, and this fragment of alpha-subunit was cloned and sequenced subsequently. The results revealed that the mature alpha-subunit of Xianju chicken was a fragment of 113 amino acids containing one glycosylation site and seven cysteine residues. It was approximately 98% and 61.4%-68.7% identical in nucleotide sequence, 97.3% and 64.6%-69% similar in deduced amino acid sequence, respectively, in the mature region to the chicken and mammalian inhibin alpha-subunit cDNA clone. As for the mature chicken inhibin alpha-subunit, the number of potential glycosylation site and cysteine residues was the same, and their corresponding positions in the amino acid sequences were almost identical as compared to chicken and mammalian inhibin alpha-subunit, which indicated that the inhibin alpha-subunit was highly conserved among different species, implying an important role of inhibin alpha-subunit in various animals. The quantitative analysis of competitive RT-PCR for inhibin alpha-subunit revealed that the expression of alpha-subunit decreased with further follicle maturity from SYF to F1 follicle. The highest level of inhibin alpha-subunit mRNA was found in the SYF and F6-8 follicles, which indicated that inhibin alpha-subunit played an important role during the course of follicular recruitment, selection and dominance.

[Expression of inhibin alpha and inhibin/activin beta A subunits in the developing follicles of the duck]

The very sensitive quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR) was used to investigate the expression of mRNA for the inhibin alpha and inhibin/activin beta A subunit in the developing ovarian follicles of the duck. The results indicated all follicles showed the expression of mRNA for the inhibin alpha and inhibin/activin beta A. The inhibin alpha subunit mRNA is expressed more abundantly than the beta A subunit in the large preovulatory follicles. Competitive RT-PCR revealed that the expression of inhibin alpha subunit is the highest in small yellow follicles (SYF), the mean relative content for the F1, F2, F3, F4/5 and LWF (large white follicle) was 0.26 +/- 0.05, 0.28 +/- 0.07, 0.57 +/- 0.12, 0.98 +/- 0.09 and 0.026 +/- 0.006, respectively, compared to a mean relative content of 1.00 for the SYF. The highest level of inhibin/activin beta A mRNA was found in the F1 follicle, the mean relative content for the F2, F3, F4/5, SYF and LWF was 0.218 +/- 0.09, 0.111 +/- 0.03, 0.058 +/- 0.011, 0.053 +/- 0.013 and 0.005 +/- 0.002, respectively, compared to a mean relative content of 1.00 for the F1 follicle. Our data suggest that the expression of the alpha subunit is reduced with follicular development whereas beta A subunit expression is dramatically enhanced, which indicates the expression of inhibin alpha and inhibin/activin beta A subunit is differentially regulated during follicular development. In addition, the highest level of beta A mRNA in F1 follicle indicates the production of dimeric inhibin and/or activin primarily occurred in the largest F1 follicle.

Use of hypoxia-regulated gene expression in tumor-specific gene therapy

The presence of hypoxic cells in human solid tumors is an important factor leading to resistance to radiation therapy and chemotherapy. However, differences in the oxygen tension between normal tissues and tumors also provide the potential for designing tumor-specific gene therapy. The strategy is to selectively induce the expression of suicide genes under hypoxia and thereby preferentially kill hypoxic cells. The hypoxia-responsive vector regulates gene expression via the hypoxia-responsive element, which can be activated through the transcriptional complex hypoxia-inducible factor 1. A gene therapy that is based on hypoxia-regulated gene expression needs to consider the suicide gene, the genetic vector, the delivery method and the bystander effect. These factors pose considerable challenges for the development of a successful hypoxia-directed gene therapy, but once this has been achieved, this type of therapy in combination with traditional radiation and chemotherapy should provide an improved clinical outcome for patients with these diseases.

[Studies of the origin of Chinese domestic fowls]

A total of 539 bases fragment of mitochondrial DNA D-loop region of six domestic chicken breeds (30 individuals) were sequenced and compared to that of red junglefowl, grey junglefowl, green junglefowl and Lafayette's junglefowl issued in GenBank, and the phylogenetic trees for the chickens constructed based on the D-loop sequences. The results indicated that the four species of genus Gallus had great differences between each other, the G. g. domesticus was the next of kin to red junglefowl in Thailand and its adjacent regions, and near of kin to red junglefowl in Indonesian, Lafayette's junglefowl, grey junglefowl and green junglefowl one by one in proper order, suggesting that the red junglefowl in Thailand and its neighbour areas sufficed as the matriarchic ancestor of Chinese domestic fowls. It was also discovered that the two subspecies of Thailand i.e. G. g. gallus and G. g. spadiceus should belong to one subspecies because of their far lower differentiation compared to that among the domestic breeds.

A hypoxia-regulated adeno-associated virus vector for cancer-specific gene therapy

The presence of hypoxic cells in human brain tumors is an important factor leading to resistance to radiation therapy. However, this physiological difference between normal tissues and tumors also provides the potential for designing cancer-specific gene therapy. We compared the increase of gene expression under anoxia (<0.01% oxygen) produced by 3, 6, and 9 copies of hypoxia-responsive elements (HRE) from the erythropoietin gene (Epo), which are activated through the transcriptional complex hypoxia-inducible factor 1 (HIF-1). Under anoxic conditions, nine copies of HRE (9XHRE) yielded 27- to 37-fold of increased gene expression in U-251 MG and U-87 MG human brain tumor cell lines. Under the less hypoxic conditions of 0.3% and 1% oxygen, gene activation by 9XHRE increased expression 11- to 18-fold in these cell lines. To generate a recombinant adeno-associated virus (rAAV) in which the transgene can be regulated by hypoxia, we inserted the DNA fragment containing 9XHRE and the LacZ reporter gene into an AAV vector. Under anoxic conditions, this vector produced 79- to 110-fold increase in gene expression. We believe this hypoxia-regulated rAAV vector will provide a useful delivery vehicle for cancer-specific gene therapy.

Overexpression of 1-acyl-glycerol-3-phosphate acyltransferase-alpha enhances lipid storage in cellular models of adipose tissue and skeletal muscle

Plasma nonesterified fatty acids (NEFA) at elevated concentrations antagonize insulin action and thus may play a critical role in the development of insulin resistance in type 2 diabetes. Plasma NEFA and glucose concentrations are regulated, in part, by their uptake into peripheral tissues. Cellular energy uptake can be increased by enhancing either energy transport or metabolism. The effects of overexpression of 1-acylglycerol-3-phosphate acyltransferase (AGAT)-alpha, which catalyzes the second step in triglyceride formation from glycerol-3-phosphate, was studied in 3T3-L1 adipocytes and C2C12 myotubes. In myotubes, overexpression of AGAT-alpha did not affect total [14C]glucose uptake in the presence or absence of insulin, whereas insulin-stimulated [14C]glucose conversion to cellular lipids increased significantly (33%, P = 0.004) with a concomitant decrease (-30%, P = 0.005) in glycogen formation. [3H]oleic acid (OA) uptake in AGAT-overexpressing myotubes increased 34% (P = 0.027) upon insulin stimulation. AGAT-alpha overexpression in adipocytes increased basal (130%, P = 0.04) and insulin-stimulated (27%, P = 0.01) [3H]OA uptake, increased insulin-stimulated glucose uptake (56%, P = 0.04) and conversion to cellular lipids (85%, P = 0.007), and suppressed basal (-44%, P = 0.01) and isoproterenol-stimulated OA release (-45%, P = 0.03) but not glycerol release. Our data indicate that an increase in metabolic flow to triglyceride synthesis can inhibit NEFA release, increase NEFA uptake, and promote insulin-mediated glucose utilization in 3T3-L1 adipocytes. In myotubes, however, AGAT-alpha overexpression does not increase basal cellular energy uptake, but can enhance NEFA uptake and divert glucose from glycogen synthesis to lipogenesis upon insulin stimulation.

Near-infrared spectroscopic study of [AlO4Al12(OH)23(H2O)12]7+-O-Si(OH)3 nitrate crystals formed by forced hydrolysis of Al3+ in the presence of TEOS

The polymer [AlO4Al12(OH)23(H2O)12]7+-O-Si(OH)3 was prepared by forced hydrolysis of Al3+ up to an OH/Al molar ratio of 2.0 in the presence of monomeric orthosilicic acid. Crystalline material was obtained by slow evaporation. Although the near-infrared spectra of the Al13-sulfate and Al13-O-Si(OH)3 are very similar, there are differences related to the bonding of the -O-Si(OH)3 group to the Al13-unit. The strong complex of bands around 7000 cm(-1) associated with the overtones and combination bands of the OH-stretching modes for Al13-sulfate is much weaker for Al13-O-Si(OH)3 and the opposite is true for the complex of bands around 5000 cm(-1) associated with the water overtone and combination modes, suggesting that the outer OH-groups of the Al13-unit are involved in the formation of the new Al13-O-Si(OH)3 units. A weak band around 7370-7631 cm(-1) is interpreted as the overtone of the Si-OH stretching vibration around 3740 cm(-1). A low intensity band, absent for Al13-sulfate and -nitrate is observed around 5550-5570 cm(-1) and is interpreted as the overtone of the OH-stretching mode of the OH-groups in the vicinity of the central AlO4 in the Al13-unit around 2890-2935 cm(-1). The interaction between the -O-Si(OH)3 group and the Al13-unit has a small influence on other bands like the combination modes of water in the 4400-4800 cm(-1) region, which show a small shift towards higher wavenumbers. The internal OH-groups in the Al13-complex are relatively shielded by the water molecules and therefore do not reflect the influence of the -O-Si(OH)3 in their band positions.

Non-opioid antinociceptive effects of supraspinal histogranin and related peptides: possible involvement of central dopamine D(2) receptor

The antinociceptive effects of intracerebroventricular (ICV) administration of histogranin (HN) and related peptides were assessed in the mouse writhing and tail-flick assays. In the writhing test, the peptides displayed dose-dependent analgesic effects with an AD(50) of 23.9 nmol/mouse for HN and the following order for other peptides: HN-(7-15)<histone H4-(86-100) approximately HN approximately HN-(7-10)<[Ser(1)]HN<osteogenic growth peptide (OGP) approximately HN-(1-10). HN-(6-9) and HN-(8-10) did not show any significant analgesic activity at 50 nmol/mouse. The importance of the C- and N-terminal amino acids in the analgesic activity of the peptides was demonstrated by the prolonged effects of HN and [Ser(1)]HN ( approximately 30 min) compared with those of HN fragments (HN-(7-15), HN-(1-10) and HN-(7-10): 5-10 min). The analgesic activity of [Ser(1)]HN (50 nmol/mouse) was not affected by the coadministration of opioid (naloxone, 1 nmol/mouse), NMDA (CPP, 0.3 and MK-801, 0.3 nmol/mouse) and D(1) (SCH-23390, 0.5 nmol/mouse) receptor antagonists, but it was significantly antagonized by the coinjection of the D(2) receptor antagonist raclopride (0.5 nmol/mouse). In the mouse tail-flick assay, HN and related peptides (50 nmol/mouse) also showed significant analgesic activity (15-35% MPE). The analgesic effect of [Ser(1)]HN was dose-dependent and, at 75 nmol/mouse, lasted for up to 45 min, and was partially blocked by the coadministration of raclopride (1 nmol/mouse), but not naloxone (2 nmol/mouse). In the mouse rotarod assay, relative high doses (75-100 nmol/mouse) of HN and related peptides did not significantly affect motor coordination. These results indicate that supraspinal administration of HN and related peptides induce significant non-opioid analgesic effects devoid of motor activity by a mechanism that involves the participation of central dopamine D(2) receptors.

BAD Ser-155 phosphorylation regulates BAD/Bcl-XL interaction and cell survival

The BH3 domain of BAD mediates its death-promoting activities via heterodimerization to the Bcl-XL family of death regulators. Growth and survival factors inhibit the death-promoting activity of BAD by stimulating phosphorylation at multiple sites including Ser-112 and Ser-136. Phosphorylation at these sites promotes binding of BAD to 14-3-3 proteins, sequestering BAD away from the mitochondrial membrane where it dimerizes with Bcl-XL to exert its killing effects. We report here that the phosphorylation of BAD at Ser-155 within the BH3 domain is a second phosphorylation-dependent mechanism that inhibits the death-promoting activity of BAD. Protein kinase A, RSK1, and survival factor signaling stimulate phosphorylation of BAD at Ser-155, blocking the binding of BAD to Bcl-XL. RSK1 phosphorylates BAD at both Ser-112 and Ser-155 and rescues BAD-mediated cell death in a manner dependent upon phosphorylation at both sites.

p90(RSK) blocks bad-mediated cell death via a protein kinase C-dependent pathway

Although activation of protein kinase C (PKC) is known to promote cell survival and protect against cell death, the PKC targets and pathways that serve this function have remained elusive. Here we demonstrate that two potent activators of PKC, 12-O-tetradecanoylphorbol-13-acetate and bryostatin, both stimulate phosphorylation of Bad at Ser(112), a site known to regulate apoptotic cell death by interleukin-3. PKC inhibitors but not PI 3-kinase/Akt inhibitors block 12-O-tetradecanoylphorbol-13-acetate-stimulated Bad phosphorylation. PKC isoforms tested in vitro were unable to phosphorylate Bad at Ser(112), suggesting that PKC acts indirectly to activate a downstream Bad kinase. p90(RSK) and family members RSK-2 and RSK-3 are activated by phorbol ester and phosphorylate Bad at Ser(112) both in vitro and in vivo. p90(RSK) stimulates binding of Bad to 14-3-3 and blocks Bad-mediated cell death in a Ser(112)-dependent manner. These findings suggest that p90(RSK) can function in a PKC-dependent pathway to promote cell survival via phosphorylation and inactivation of Bad-mediated cell death.

[Studies on immunomodulatory function of polysaccharide of Fructus Ligustri Lucidi]

OBJECTIVE

To explore the immunomodulatory mechanism of Chinese medicine Fructus Ligustri Lucidi and to find its efficient material base.

METHOD

The effects of FLLPS on the immunoactivity of mouse speen lymphocyte were studied in vitro or vivo by means of MTT.

RESULT

FLLPS could obviously promote the speen lymphocyte proliferation in normal mice and mice with Yin-deficiency selected by injection with adrenocorticortropic hormone.

CONCLUSION

FLLPS has an immunomodulatory function for both normal mice and mice with Yin-deficiency.

Killing of brain tumor cells by hypoxia-responsive element mediated expression of BAX

The presence of radioresistant hypoxic cells in human brain tumors limits the overall effectiveness of conventional fractionated radiation therapy. Tumor-specific therapies that target hypoxic cells are clearly needed. We have investigated the expression of suicide genes under hypoxia by a hypoxia-responsive element (HRE), which can be activated through hypoxia-inducible factor-1 (HIF-1). We transfected plasmids containing multiple copies of HRE into U-87 MG and U-251 MG-NCI human brain tumor cells and tested their ability to induce LacZ gene expression under anoxia. Gene expression under anoxia versus oxia was increased about 12-fold for U-87 MG cells and about fourfold for U-251 MG-NCI cells. At intermediate hypoxic conditions, increased LacZ gene expression in U-87 MG cells was induced by the plasmid that contained three HREs, but not by the plasmid with two HREs. Lastly, when we placed a suicide gene BAX under the control of HREs, cells transfected with the BAX plasmids were preferentially killed through apoptosis under anoxia. Our studies demonstrate that HRE-regulated gene expression is active in brain tumor cells, and that the amount of increased gene expression obtained is dependent on the cell line, the HRE copy number, and the degree of hypoxia.

Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation

A novel, to our knowledge, two-step digit-set-restricted modified signed-digit (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {1, 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which can be summed to form the final result without carry generation. The operation can be performed in parallel by use of binary logic. An optical system that utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of data arrays, any complex logic operations of multiple variables can be realized without additional temporal latency of the intermediate results. This technique has a high space-bandwidth product and signal-to-noise ratio. The main structure can be stacked to construct a compact optoelectronic MSD adder-subtracter.

Compact parallel optical modified-signed-digit arithmetic-logic array processor with electron-trapping device

A compact two-step modified-signed-digit arithmetic-logic array processor is proposed. When the reference digits are programmed, both addition and subtraction can be performed by the same binary logic operations regardless of the sign of the input digits. The optical implementation and experimental demonstration with an electron-trapping device are shown. Each digit is encoded by a single pixel, and no polarization is included. Any combinational logic can be easily performed without optoelectronic and electro-optic conversions of the intermediate results. The system is compact, general purpose, simple to align, and has a high signal-to-noise ratio.

Molecular cloning of LMO41, a new human LIM domain gene

We have identified a new human LIM domain gene by isolating an autoantigenic cDNA clone from a human breast tumor cDNA library. The predicted amino acid sequence of the cDNA clone's 495 bp open reading frame contains two tandem LIM domain motifs, and within the LIM domain region there is 62% identity with the analogous region of the LIM-only gene LMO1. The homology to LMO1 is restricted to the 360 bp region encoding the tandemly repeated LIM domains, the rest of the open reading frame as well as the extensive, GC-rich 5' untranslated region, and 3' region of the 2 kb cDNA sequence are unrelated to any known genes. This gene has been designated LMO4.

The inhibitory upstream open reading frame from mammalian S-adenosylmethionine decarboxylase mRNA has a strict sequence specificity in critical positions

The upstream open reading frame (uORF) in the 5' leader of the mammalian mRNA encoding S-adenosylmethionine decarboxylase (AdoMetDC) serves as a negative regulatory element by suppressing translation of the associated downstream cistron. Certain changes in the amino acid sequence of the hexapeptide (sequence MAGDIS) encoded by the uORF destroy suppressive activity, implying specific interaction with a cellular target. In this paper, we examine the extent of alterations that can be tolerated in this uORF. The mammalian AdoMetDC uORF inhibits downstream translation when placed into the 5' leader of a yeast mRNA with characteristics resembling those in mammalian cells, suggesting that the encoded peptide has a similar target across species. Using yeast for the initial screen, we tested the specificity of the critical three codons at the 3' end of the uORF by saturation mutagenesis. Altered uORFs selected from the primary yeast screen were then retested in mammalian cells. The requirements at codons 4 and 5 were quite stringent; only aspartic acid at codon 4 yielded a fully suppressive peptide, and only valine could substitute productively for isoleucine at codon 5. The specificity at codon 6 was much looser, with many substitutions retaining suppressive activity in both yeast and mammalian cells.

[Determination of mephenytoin enantiomers in human urine using chiral capillary chromatography and its application in metabolism polymorphism study]

The determination of mephenytoin enantiomers in human urine using chiral capillary chromatography is described. MP in urine was extracted with using dichloroethane and the organic layer was washed with acidic and basic aqueous solution. The organic phase was evaporated to dryness under nitrogen on water bath (55 degrees C). The residue was dissolved in 10 microL ethyl acetate and 1 microL was injected into the GC. MP enantiomers was separated on a Chirasil-Val SFOT column with nitrogen as carrier gas and FID as detector. The linear relationship was obtained over the concentration range of 115-690 micrograms/L (r = 0.9913 for S-MP and r = 0.9934 for R-MP) with a detection limit of 60 ng MP enantiomers/mL urine. The recoveries were 74.41% for S-MP and 73.78% for R-MP. The relative standard deviation within day and between days were less than 6.5%. The method was used to study the metabolism polymorphism of 32 volunteers. The S/R ratio was calculated to express interindividual variation in metabolism, in which, the S/R ratio of 5 subjects was more than 0.95, as the poor metabolizers and that of the others was less than 0.8, as the extensive metabolizers.