A Novel Therapeutic Method in Gastro-esophageal Reflux Disease.

BACKGROUND: Gastro-esophageal reflux disease (GERD/GORD) is a chronic condition in which gastric acid flows backwards up into the esophagus, causing heart burn and a higher disposition to esophageal cancer. The reflux is caused by impairment of the lower esophageal sphincter (LES). Over the past century gastro-esophageal reflux has become the principal gastrointestinal condition of our time. The proton pump inhibitor class of drugs is effective in ameliorating the symptoms of reflux. The cost of investigation of patients in Europe is €100 billion per annum. The cost in days lost from work is €100 billion per annum in Europe. The global cost is 3 times this amount. METHODOLOGY: The proposed device for treating gastro-esophageal reflux is a biodegradable valve that is placed non surgically in the esophago-gastric junction to prevent reflux from the stomach to the esophagus. EXPERIMENT RESULTS: 50 simulator studies were performed with the patented device to elucidate the most consistent method of insertion and fixation in a human like simulator. The simulator was designed to replicate the normal human gastro-esophageal anatomy and characteristics. Four animal insertions were performed under ethical regulation at Amsterdam Medical Centre, Netherlands. Three cadaveric experiments were performed at Hackensack University Hospital, New Jersey, USA, to verify the positive outcomes of the simulator studies. CONCLUSION: Successful outcomes of simulator studies and cadaveric experiments allowed the design freeze of a NoReflux device for treating gastro-esophageal reflux disease.

A Novel Isobaric (Gas-Less) Laparoscopic Surgery Device.

BACKGROUND: Laparoscopic Surgery is performed using carbon dioxide gas insufflated into the abdominal cavity to create a space for endoscopic visualization. During a laparoscopic surgical dissection plume is formed from electrocautery dissection. This plume contains viruses and sometimes COVID-19 viruses. The plume obscures the visual field. The unfiltered plume release is dangerous to surgeons, nurses, and patients. The loss of visualization during carbon dioxide release delays surgery. The use of carbon dioxide insufflated gas can have side effects such as C02 embolus, pain from diaphragmatic stretching, physiological complications such as respiratory infections and renal problems. The release of carbon dioxide gas into the atmosphere, unfiltered is significant. This accounts for 7% of greenhouse gases globally. This percentage is rising due to expansion of minimally invasive surgery. METHODOLOGY: The proposed system for gasless surgery was designed by algorithms of tensegrity and geodesic dome pressures. EXPERIMENT RESULTS: 100 simulator studies were performed to develop the device to elevate the abdominal wall to create a gas free (isobaric) space for Laparoscopic Surgery. After design freeze, 4 animal studies were performed using ethical research guidelines at Amsterdam Medical Centre Research Department, Netherlands. 3 cadaveric studies were performed using Ethical guidelines at Hackensack University Medical Centre, New Jersey, USA, to evaluate the device in a human setting. CONCLUSIONS: These devices for Laparoscopic Surgery, Robotic Surgery, and Hand Assisted Laparoscopic Surgery (HALS) successfully proved that a superior intra-abdominal space can be created without carbon dioxide insufflation. The devices are patented in USA and Europe.

Mycobacterium tuberculosis-Induced Bronchoalveolar Lavage Gene Expression Signature in Latent Tuberculosis Infection Is Dominated by Pleiotropic Effects of CD4+ T Cell-Dependent IFN-γ Production despite the Presence of Polyfunctional T Cells within the Airways.

Tuberculosis (TB) remains a worldwide public health threat. Development of a more effective vaccination strategy to prevent pulmonary TB, the most common and contagious form of the disease, is a research priority for international TB control. A key to reaching this goal is improved understanding of the mechanisms of local immunity to Mycobacterium tuberculosis, the causative organism of TB. In this study, we evaluated global M. tuberculosis-induced gene expression in airway immune cells obtained by bronchoalveolar lavage (BAL) of individuals with latent TB infection (LTBI) and M. tuberculosis-naive controls. In prior studies, we demonstrated that BAL cells from LTBI individuals display substantial enrichment for M. tuberculosis-responsive CD4+ T cells compared with matched peripheral blood samples. We therefore specifically assessed the impact of the depletion of CD4+ and CD8+ T cells on M. tuberculosis-induced BAL cell gene expression in LTBI. Our studies identified 12 canonical pathways and a 47-gene signature that was both sensitive and specific for the contribution of CD4+ T cells to local recall responses to M. tuberculosis In contrast, depletion of CD8+ cells did not identify any genes that fit our strict criteria for inclusion in this signature. Although BAL CD4+ T cells in LTBI displayed polyfunctionality, the observed gene signature predominantly reflected the impact of IFN-γ production on a wide range of host immune responses. These findings provide a standard for comparison of the efficacy of standard bacillus Calmette-Guérin vaccination as well as novel TB vaccines now in development at impacting the initial response to re-exposure to M. tuberculosis in the human lung.

The myeloid transcription factor KLF2 regulates the host response to polymicrobial infection and endotoxic shock.

Precise control of myeloid cell activation is required for optimal host defense. However, this activation process must be under exquisite control to prevent uncontrolled inflammation. Herein, we identify the Kruppel-like transcription factor 2 (KLF2) as a potent regulator of myeloid cell activation in vivo. Exposure of myeloid cells to hypoxia and/or bacterial products reduced KLF2 expression while inducing hypoxia inducible factor-1α (HIF-1α), findings that were recapitulated in human septic patients. Myeloid KLF2 was found to be a potent inhibitor of nuclear factor-kappaB (NF-κB)-dependent HIF-1α transcription and, consequently, a critical determinant of outcome in models of polymicrobial infection and endotoxemia. Collectively, these observations identify KLF2 as a tonic repressor of myeloid cell activation in vivo and an essential regulator of the innate immune system.

Identification of early transcriptome signatures in placenta exposed to insulin and obesity.

OBJECTIVE: The purpose of this study was to investigate the effects of insulin on human placental transcriptome and biological processes in first-trimester pregnancy. STUDY DESIGN: Maternal plasma and placenta villous tissue were obtained at the time of voluntary termination of pregnancy (7-12 weeks) from 17 lean (body mass index, 20.9±1.5 kg/m2) and 18 obese (body mass index, 33.5±2.6 kg/m2) women. Trophoblast cells were immediately isolated for in vitro treatment with insulin or vehicle. Patterns of global gene expression were analyzed using genome microarray profiling after hybridization to Human Gene 1.1 ST and real time reverse transcription-polymerase chain reaction. RESULTS: The global trophoblast transcriptome was qualitatively separated in insulin-treated vs untreated trophoblasts of lean women. The number of insulin-sensitive genes detected in the trophoblasts of lean women was 2875 (P<.001). Maternal obesity reduced the number of insulin-sensitive genes recovered by 30-fold. Insulin significantly impaired several gene networks regulating cell cycle and cholesterol homeostasis but did not modify pathways related to glucose transport. Obesity associated with high insulin and insulin resistance, but not maternal hyperinsulinemia alone, impaired the global gene profiling of early gestation placenta, highlighting mitochondrial dysfunction and decreased energy metabolism. CONCLUSION: We report for the first time that human trophoblast cells are highly sensitive to insulin regulation in early gestation. Maternal obesity associated with insulin resistance programs the placental transcriptome toward refractoriness to insulin with potential adverse consequences for placental structure and function.

The microRNAs, MiR-31 and MiR-375, as candidate markers in Barrett's esophageal carcinogenesis.

There is a critical need to identify molecular markers that can reliably aid in stratifying esophageal adenocarcinoma (EAC) risk in patients with Barrett's esophagus. MicroRNAs (miRNA/miR) are one such class of biomolecules. In the present cross-sectional study, we characterized miRNA alterations in progressive stages of neoplastic development, i.e., metaplasia-dysplasia-adenocarcinoma, with an aim to identify candidate miRNAs potentially associated with progression. Using next generation sequencing (NGS) as an agnostic discovery platform, followed by quantitative real-time PCR (qPCR) validation in a total of 20 EACs, we identified 26 miRNAs that are highly and frequently deregulated in EACs (≥ 4-fold in >50% of cases) when compared to paired normal esophageal squamous (nSQ) tissue. We then assessed the 26 EAC-derived miRNAs in laser microdissected biopsy pairs of Barrett's metaplasia (BM)/nSQ (n = 15), and high-grade dysplasia (HGD)/nSQ (n = 14) by qPCR, to map the timing of deregulation during progression from BM to HGD and to EAC. We found that 23 of the 26 candidate miRNAs were deregulated at the earliest step, BM, and therefore noninformative as molecular markers of progression. Two miRNAs, miR-31 and -31*, however, showed frequent downregulation only in HGD and EAC cases suggesting association with transition from BM to HGD. A third miRNA, miR-375, showed marked downregulation exclusively in EACs and in none of the BM or HGD lesions, suggesting its association with progression to invasive carcinoma. Taken together, we propose miR-31 and -375 as novel candidate microRNAs specifically associated with early- and late-stage malignant progression, respectively, in Barrett's esophagus.

Jagged-1 is induced by mTOR inhibitors in renal cancer cells through an Akt/ALK5/Smad4-dependent mechanism.

The mammalian target of rapamycin (mTOR) plays an important role in the aggressiveness and therapeutic resistance of many cancers. Targeting mTOR continues to be under clinical investigation for cancer therapy. Despite the notable clinical success of mTOR inhibitors in extending the overall survival of patients with certain malignancies including metastatic renal cell carcinomas (RCCs), the overall impact of mTOR inhibitors on cancers has been generally disappointing and attributed to various compensatory responses. Here we provide the first report that expression of the Notch ligand Jagged-1 (JAG1), which is associated with aggressiveness of RCCs, is induced by several inhibitors of mTOR (rapamycin (Rap), BEZ235, KU-0063794) in human clear cell RCC (ccRCC) cells. Using both molecular and chemical inhibitors of PI3K, Akt, and TGF-ß signaling, we provide evidence that the induction of JAG1 expression by mTOR inhibitors in ccRCC cells depends on the activation of Akt and occurs through an ALK5 kinase/Smad4-dependent mechanism. Furthermore, we show that mTOR inhibitors activate Notch1 and induce the expression of drivers of epithelial-mesenchymal transition, notably Hic-5 and Slug. Silencing JAG1 with selective shRNAs blocked the ability of KU-0063794 and Rap to induce Hic-5 in ccRCC cells. Moreover, Rap enhanced TGF-ß-induced expression of Hic-5 and Slug, both of which were repressed in JAG1-silenced ccRCC cells. Silencing JAG1 selectively decreased the motility of ccRCC cells treated with Rap or TGF-ß1. Moreover, inhibition of Notch signaling with γ-secretase inhibitors enhanced or permitted mTOR inhibitors to suppress the motility of ccRCC cells. We suggest targeting JAG1 may enhance therapeutic responses to mTOR inhibitors in ccRCCs.

Distinct transcriptomes define rostral and caudal serotonin neurons.

The molecular architecture of developing serotonin (5HT) neurons is poorly understood, yet its determination is likely to be essential for elucidating functional heterogeneity of these cells and the contribution of serotonergic dysfunction to disease pathogenesis. Here, we describe the purification of postmitotic embryonic 5HT neurons by flow cytometry for whole-genome microarray expression profiling of this unitary monoaminergic neuron type. Our studies identified significantly enriched expression of hundreds of unique genes in 5HT neurons, thus providing an abundance of new serotonergic markers. Furthermore, we identified several hundred transcripts encoding homeodomain, axon guidance, cell adhesion, intracellular signaling, ion transport, and imprinted genes associated with various neurodevelopmental disorders that were differentially enriched in developing rostral and caudal 5HT neurons. These findings suggested a homeodomain code that distinguishes rostral and caudal 5HT neurons. Indeed, verification studies demonstrated that Hmx homeodomain and Hox gene expression defined an Hmx(+) rostral subtype and Hox(+) caudal subtype. Expression of engrailed genes in a subset of 5HT neurons in the rostral domain further distinguished two subtypes defined as Hmx(+)En(+) and Hmx(+)En(-). The differential enrichment of gene sets for different canonical pathways and gene ontology categories provided additional evidence for heterogeneity between rostral and caudal 5HT neurons. These findings demonstrate a deep transcriptome and biological pathway duality for neurons that give rise to the ascending and descending serotonergic subsystems. Our databases provide a rich, clinically relevant resource for definition of 5HT neuron subtypes and elucidation of the genetic networks required for serotonergic function.

microRNA 184 regulates expression of NFAT1 in umbilical cord blood CD4+ T cells.

The reduced expression of nuclear factor of activated T cells-1 (NFAT1) protein in umbilical cord blood (UCB)-derived CD4+ T cells and the corresponding reduction in inflammatory cytokine secretion after stimulation in part underlies their phenotypic differences from adult blood (AB) CD4+ T cells. This muted response may contribute to the lower incidence and severity of high-grade acute graft-versus-host disease (aGVHD) exhibited by UCB grafts. Here we provide evidence that a specific microRNA, miR-184, inhibits NFAT1 protein expression elicited by UCB CD4+ T cells. Endogenous expression of miR-184 in UCB is 58.4-fold higher compared with AB CD4+ T cells, and miR-184 blocks production of NFAT1 protein through its complementary target sequence on the NFATc2 mRNA without transcript degradation. Furthermore, its negative effects on NFAT1 protein and downstream interleukin-2 (IL-2) transcription are reversed through antisense blocking in UCB and can be replicated via exogenous transfection of precursor miR-184 into AB CD4+ T cells. Our findings reveal a previously uncharacterized role for miR-184 in UCB CD4+ T cells and a novel function for microRNA in the early adaptive immune response.

Molecular phenotype of monocytes at the maternal-fetal interface.

OBJECTIVE: The purpose of this study was to gain insight into the pathways that are associated with inflammation at the maternal-fetal interface. This study examined the molecular characteristics of monocytes that were derived from the maternal circulation and the placenta of obese women. STUDY DESIGN: Mononuclear cells were isolated from placenta, venous maternal, and umbilical cord blood at term delivery; activated monocytes were separated with CD14 immunoselection. The genotype and expression pattern of the monocytes were analyzed by microarray and real-time reverse transcriptase-polymerase chain reaction. RESULTS: The transcriptome of the maternal blood and placental CD14 monocytes exhibited 73% homology, with 10% (1800 common genes) differentially expressed. Genes for immune sensing and regulation, matrix remodeling, and lipid metabolism were enhanced 2-2006 fold in placenta, compared with maternal monocytes. The CD14 placental monocytes exhibited a maternal genotype (9% DYS14 expression) as opposed to the fetal genotype (90% DYS14 expression) of the trophoblast cells. CONCLUSION: CD14 monocytes from the maternal blood and the placenta share strong phenotypic and genotypic similarities with an enhanced inflammatory pattern in the placenta. The functional traits of the CD14 blood and placental monocytes suggest that they both contribute to propagation of inflammation at the maternal-fetal interface.

Elevated AF1q expression is a poor prognostic marker for adult acute myeloid leukemia patients with normal cytogenetics.

Nearly half of the patients with newly diagnosed acute myeloid leukemia have normal cytogenetics (NC-AML) and are classified as intermediate risk, but their 5-year overall survival (OS) ranges from 24 to 42%. Therefore, molecular biomarkers to identify poor-risk patients are needed. Elevated AF1q expression in the absence of specific poor cytogenetics is associated with poor outcomes in pediatric patients with AML and adult patients with myelodysplastic syndrome. We examined AF1q expression in 290 patients with NC-AML. We found that patients with low AF1q (n = 73) expression (AF1q(low)) have better OS (P = 0.026), disease-free survival (P = 0.1), and complete remission rate (P = 0.06) when compared with patients with high AF1q expression (AF1q(high) n = 217). The patients with AF1q(high) had significantly greater incidence of concurrent tyrosine kinase3 internal tandem duplication. A subgroup of the patients with AF1q(high) who received allogeneic stem cell transplantation (SCT) had a significant better relapse-free survival when compared with patients who received chemotherapy/autologous SCT (P = 0.04). This study suggests that high AF1q expression is a poor prognostic marker for adult patients with NC-AML.

Phenotypic differences between healthy effector CTL and leukemic LGL cells support the notion of antigen-triggered clonal transformation in T-LGL leukemia.

T cell large granular lymphocyte leukemia (T-LGL) is a chronic clonal lymphoproliferation of CTL. In many ways, T-LGL clones resemble terminal effector CTL, including down-modulation of CD28 and overexpression of perforin, granzymes, and CD57. We studied the transcriptome of T-LGL clones and compared it with healthy CD8+CD57+ effector cells as well as CD8+CD57- populations. T-LGL clones were sorted based on their TCR variable beta-chain restriction, and controls were obtained by pooling cell populations from 14 donors. Here, we focus our analysis on immunological networks, as immune mechanisms play a prominent role in the etiology of bone marrow failure in T-LGL. Informative genes identified by expression arrays were studied further in an independent cohort of patients using Taqman PCR, ELISA assays, and FACS analysis. Despite a strikingly similar gene expression profile between T-LGL clones and their healthy counterparts, important phenotypic differences were identified, including up-modulation of TNFRS9, myeloid cell leukemia sequence 1, IFN-gamma, and IFN-gamma-related genes, and several integrins/adhesion molecules. In addition, T-LGL clones were characterized by an overexpression of chemokines and chemokine receptors that are typically associated with viral infections (CXCL2, Hepatitis A virus cellular receptor 1, IL-18, CCR2). Our studies suggest that immunodominant LGL clones, although phenotypically similar to effector CTL, show significantly altered expression of a number of genes, including those associated with an ongoing viral infection or chronic, antigen-driven immune response.

Gene expression microarrays and respiratory muscles.

The routine measurement of the expression of tens of thousands of gene transcripts, simultaneously, is a defining advance of the last decade which has been made possible by microarray technology. Using this very powerful approach, a pattern has emerged from a number of studies that suggest a molecular niche for the diaphragm which is quite different from that occupied by limb muscle. All indications are that this is true not only in regard to differential gene transcription patterns in healthy muscles but also in the changes in transcription occurring in association with different diseases. Furthermore, respiratory muscle mounts a rich gene expression response to a number of disturbances, be they primary genetic defects (e.g. various types of muscular dystrophies) or non-genetic perturbations (e.g. controlled mechanical ventilation). Large numbers of genes undergo altered levels of transcription, ranging from tens to hundreds (typical) to thousands. These genes are involved in diverse cellular processes, such as contraction, intermediate metabolism, oxidative stress, apoptosis and cellular adhesion. Functional groups of genes identified as having changed expression differ in many respects from one disease to another. Previously identified pathways of muscle injury and repair are often perturbed to greater extents than previously anticipated, and processes not previously suspected of having important roles in the pathophysiology of specific disorders have been identified. Elucidation of these under-appreciated molecular events may lead to novel therapeutic interventions based on disrupting the downstream adverse consequences of the primary event or facilitating events which ameliorate the injury and/or promote muscle healing.

Molecular changes associated with the endolymphatic hydrops model.

HYPOTHESIS: Hearing loss and cochlear degeneration in the guinea pig model of endolymphatic hydrops (ELH) results, in part, from toxic levels of excitatory amino acids (EAAs) such as glutamate, which in turn leads to changes in the expression of genes linked to intracellular glutamate homeostasis and apoptosis, leading to neuronal cell death. BACKGROUND: EAAs have been shown to play a role in normal auditory signal transmission in mammalian cochlea, but have also been implicated in neurotoxicity when levels are elevated. Changes in the expression of specific genes involved in the glutamatergic and apoptotic pathway would serve as evidence for excitotoxicity linked to elevated levels of glutamate. METHODS: Guinea pigs underwent surgical obliteration of the endolymphatic duct, and then a timed harvest of the treated (right) and control (left) cochlea and subsequent quantification of gene expression via real-time quantitative polymerase chain reaction. RESULTS: Quantitative polymerase chain reaction data show significant upregulation of glutamate aspartate transporter and neuronal nitric oxide synthase mRNA levels 3 weeks postsurgery and Caspase 3 mRNA levels 1 week postsurgery. No significant changes were detected in glutamine synthetase expression levels. CONCLUSION: Upregulation of genes involved in glutamate homeostasis and the apoptotic pathway in animals treated with endolymphatic duct obstruction (usually associated with secondary ELH) support the hypothesis that EAAs may play a role in the pathophysiology of ELH-related cochlear injury. Inhibitors to these pathways can be useful for the study of new avenues to delay or prevent ELH-related hearing loss.

A nonrandomized trial of vitamin D supplementation for Barrett's esophagus.

BACKGROUND: Vitamin D deficiency may increase esophageal cancer risk. Vitamin D affects genes regulating proliferation, apoptosis, and differentiation and induces the tumor suppressor 15-hydroxyprostaglandin dehydrogenase (PGDH) in other cancers. This nonrandomized interventional study assessed effects of vitamin D supplementation in Barrett's esophagus (BE). We hypothesized that vitamin D supplementation may have beneficial effects on gene expression including 15-PGDH in BE. METHODS: BE subjects with low grade or no dysplasia received vitamin D3 (cholecalciferol) 50,000 international units weekly plus a proton pump inhibitor for 12 weeks. Esophageal biopsies from normal plus metaplastic BE epithelium and blood samples were obtained before and after vitamin D supplementation. Serum 25-hydroxyvitamin D was measured to characterize vitamin D status. Esophageal gene expression was assessed using microarrays. RESULTS: 18 study subjects were evaluated. The baseline mean serum 25-hydroxyvitamin D level was 27 ng/mL (normal ≥30 ng/mL). After vitamin D supplementation, 25-hydroxyvitamin D levels rose significantly (median increase of 31.6 ng/mL, p<0.001). There were no significant changes in gene expression from esophageal squamous or Barrett's epithelium including 15-PGDH after supplementation. CONCLUSION: BE subjects were vitamin D insufficient. Despite improved vitamin D status with supplementation, no significant alterations in gene expression profiles were noted. If vitamin D supplementation benefits BE, a longer duration or higher dose of supplementation may be needed.

Gene expression profiling of diaphragm muscle in alpha2-laminin (merosin)-deficient dy/dy dystrophic mice.

Deficiency of alpha2-laminin (merosin) underlies classical congenital muscular dystrophy in humans and dy/dy muscular dystrophy in mice and causes severe muscle dysfunction in both species. To gain greater insight into the biochemical and molecular events that link alpha2-laminin deficiency with muscle fiber necrosis, and the associated compensatory responses, gene expression profiles were characterized in diaphragm muscle from 8-wk-old dy/dy mice using oligonucleotide microarrays. Compared with age-matched normal muscle, dystrophic diaphragm was characterized by predominantly augmented gene expression, irrespective of the fold-change threshold. Among the 69 genes with at least plus or minus twofold significantly altered expression, 30 belonged to statistically overrepresented Gene Ontology (GO) biological process groups. These covered four specific themes: development including muscle development, cell motility with an emphasis on muscle contraction, defense/immune response, and cell adhesion. An additional 11 gene transcripts were assigned to more general overrepresented GO biological process groups (e.g., cellular process, organismal physiological process); the remaining 28 did not belong to any overrepresented groups. GO cellular constituent assignment resulted in the highest degree of overrepresentation in extracellular and muscle fiber locations, whereas GO molecular function assignment was most notable for various types of binding. RT-PCR was performed on 38 of 41 genes with at least plus or minus twofold significantly altered expression that were assigned to overrepresented GO biological process groups, with expression changes verified for 36 of 38 genes. These results indicate that several specific groups of genes have altered expression in response to genetic alpha2-laminin deficiency, with both similarities and differences compared with data reported for dystrophin-deficient muscular dystrophies.

Transcriptomic-metabolomic reprogramming in EGFR-mutant NSCLC early adaptive drug escape linking TGFß2-bioenergetics-mitochondrial priming.

The impact of EGFR-mutant NSCLC precision therapy is limited by acquired resistance despite initial excellent response. Classic studies of EGFR-mutant clinical resistance to precision therapy were based on tumor rebiopsies late during clinical tumor progression on therapy. Here, we characterized a novel non-mutational early adaptive drug-escape in EGFR-mutant lung tumor cells only days after therapy initiation, that is MET-independent. The drug-escape cell states were analyzed by integrated transcriptomic and metabolomics profiling uncovering a central role for autocrine TGFß2 in mediating cellular plasticity through profound cellular adaptive Omics reprogramming, with common mechanistic link to prosurvival mitochondrial priming. Cells undergoing early adaptive drug escape are in proliferative-metabolic quiescent, with enhanced EMT-ness and stem cell signaling, exhibiting global bioenergetics suppression including reverse Warburg, and are susceptible to glutamine deprivation and TGFß2 inhibition. Our study further supports a preemptive therapeutic targeting of bioenergetics and mitochondrial priming to impact early drug-escape emergence using EGFR precision inhibitor combined with broad BH3-mimetic to interrupt BCL-2/BCL-xL together, but not BCL-2 alone.

Comprehensive expression profiling by muscle tissue class and identification of the molecular niche of extraocular muscle.

Muscle tissue is an elegant model for biologic integration of structure with function and is frequently affected by a variety of inherited diseases. Traditional muscle classes--skeletal, cardiac, and smooth--share basic aspects of contractile and energetics mechanisms but also have distinctive role-specific adaptations. We used large-scale oligonucleotide microarrays to broaden knowledge of the adaptive expression patterns underlying muscle tissue differences and to identify transcript subsets that are most likely to represent candidate disease genes. Using stringent analysis criteria, we found >or=95 transcripts, which were preferentially expressed by each muscle class and were validated by inclusion of known muscle class-specific and inherited disease-related genes. Differentially expressed transcripts not previously identified as class-specific extend understanding of muscle class transcriptomes and may represent novel muscle-specific disease genes. We also analyzed the expression profile of extraocular muscle, which is divergent from other skeletal muscles, in the broader context of all major muscle classes. Data show that the extraocular muscle phenotype results from the combination of tissue-specific transcripts, novel expression levels of skeletal muscle transcripts, and partial sharing of gene expression patterns with cardiac and smooth muscle. These, and additional proteomic data, establish that extraocular muscle does not constitute a distinctive muscle class but that it does occupy a novel niche within the skeletal muscle class.

Constitutive properties, not molecular adaptations, mediate extraocular muscle sparing in dystrophic mdx mice.

Extraocular muscle (EOM) is spared in Duchenne muscular dystrophy. Here, we tested putative EOM sparing mechanisms predicted from existing dystrophinopathy models. Data show that mdx mouse EOM contains dystrophin-glycoprotein complex (DGC)-competent and DGC-deficient myofibers distributed in a fiber type-specific pattern. Up-regulation of a dystrophin homologue, utrophin, mediates selective DGC retention. Counter to the DGC mechanical hypothesis, an intact DGC is not a precondition for EOM sarcolemmal integrity, and active adaptation at the level of calcium homeostasis is not mechanistic in protection. A partial, fiber type-specific retention of antiischemic nitric oxide to vascular smooth muscle signaling is not a factor in EOM sparing, because mice deficient in dystrophin and alpha-syntrophin, which localizes neuronal nitric oxide synthase to the sarcolemma, have normal EOMs. Moreover, an alternative transmembrane protein, alpha7beta1 integrin, does not appear to substitute for the DGC in EOM. Finally, genomewide expression profiling showed that EOM does not actively adapt to dystrophinopathy but identified candidate genes for the constitutive protection of mdx EOM. Taken together, data emphasize the conditional nature of dystrophinopathy and the potential importance of nonmechanical DGC roles and support the hypothesis that broad, constitutive structural cell signaling, and/or biochemical differences between EOM and other skeletal muscles are determinants of differential disease responsiveness.

Conserved and muscle-group-specific gene expression patterns shape postnatal development of the novel extraocular muscle phenotype.

Current models in skeletal muscle biology do not fully account for the breadth, causes, and consequences of phenotypic variation among skeletal muscle groups. The muscle allotype concept arose to explain frank differences between limb, masticatory, and extraocular (EOM) muscles, but there is little understanding of the developmental regulation of the skeletal muscle phenotypic range. Here, we used morphological and DNA microarray analyses to generate a comprehensive temporal profile for rat EOM development. Based upon coordinate regulation of morphologic/gene expression traits with key events in visual, vestibular, and oculomotor system development, we propose a model that the EOM phenotype is a consequence of extrinsic factors that are unique to its local environment and sensory-motor control system, acting upon a novel myoblast lineage. We identified a broad spectrum of differences between the postnatal transcriptional patterns of EOM and limb muscle allotypes, including numerous transcripts not traditionally associated with muscle fiber/group differences. Several transcription factors were differentially regulated and may be responsible for signaling muscle allotype specificity. Significant differences in cellular energetic mechanisms defined the EOM and limb allotypes. The allotypes were divergent in many other functional transcript classes that remain to be further explored. Taken together, we suggest that the EOM allotype is the consequence of tissue-specific mechanisms that direct expression of a limited number of EOM-specific transcripts and broader, incremental differences in transcripts that are conserved by the two allotypes. This represents an important first step in dissecting allotype-specific regulatory mechanisms that may, in turn, explain differential muscle group sensitivity to a variety of metabolic and neuromuscular diseases.