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Microarray Analysis Gene Expression Profiles in Laryngeal Muscle After Recurrent Laryngeal Nerve Injury

ABSTRACT: The pathophysiology of recurrent laryngeal nerve (RLN) transection injury is rare in that it is characteristically followed by a high degree of spontaneous reinnervation, with reinnervation of the laryngeal adductor complex (AC) preceding that of the abducting posterior cricoarytenoid (PCA) muscle. Here, we aim to elucidate the differentially expressed myogenic factors following RLN injury that may be at least partially responsible for the spontaneous reinnervation. F344 male rats underwent RLN injury or sham surgery (n=12). One week after RLN injury, larynges were harvested following euthanasia. mRNA was extracted from PCA and AC muscles bilaterally, and microarray analysis was performed using a full rat genome array. Microarray analysis of denervated AC and PCA muscles demonstrated dramatic differences in gene expression profiles, with 205 individual probes that were differentially expressed between the denervated AC and PCA muscles, and only 14 genes with similar expression patterns. The differential expression patterns of the AC and PCA suggest different mechanisms of reinnervation. The PCA showed the gene patterns of Wallerian degeneration, while the AC expressed the gene patterns of reinnervation by adjacent axonal sprouting. This finding may reveal important therapeutic targets applicable to RLN and other peripheral nerve injuries.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE72361 | GEO | 2016/07/01

SECONDARY ACCESSION(S): PRJNA293872

REPOSITORIES: GEO

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Project description:Sarcopenia is the decreased muscle mass and weakness associated with aging and a major cause of morbidity and mortality in the elderly. To what extent non-locomotive muscles are susceptible to this condition is unclear. For example, age affects laryngeal function (ventilation, airway protective reflexes, swallowing and phonation). Age-related laryngeal dysfunction may be due to effects on its intrinsic muscles that have a unique phenotype: very small, mostly fast oxidative muscle fibers. For this study, we examined how age alters the functional characteristics and gene expression profile of posterior cricoarytenoid (PCA), an intrinsic laryngeal muscle. PCA muscles from Fischer 344-Brown Norway F1 hybrid rats (6 and 30 months of age) were used for cDNA microarrays, light and electron (EM) microscopy, and in vitro contractile function. Histological analyses demonstrated a ~40% increase in mean PCA fiber size and in the number of fibers with low myosin ATPase activity. There was also evidence of ragged-red fibers, a hallmark of mitochondrial dysfunction. In turn, mitochondrial volume density, determined by EM, was significantly higher in PCA muscles at 30 months (43% vs. 21% at 6 months). In vitro function showed a decrease in velocity of unloaded shortening at 30 months. Finally, cDNA microarrays demonstrated a transcriptome shift in PCA muscle with age. Gene classes with the largest changes were: signal transduction, transcription factors, and metabolic enzymes. These data demonstrate that PCA muscles are significantly altered by age. Moreover, the observed changes in muscle fiber size, mitochondrial content and gene expression profile suggest that the PCA response to age diverges from that seen in more typical skeletal muscles. Experiment Overall Design: Total RNA was obtained with TRIzol (Invitrogen Carlsbad, CA) following the manufacturers recommended protocol. Tissues from 4 animals were combined into each RNA sample to decrease inter-subject variability. Biotinylated cRNA samples were hybridized to Affymetrix Rat Genome U34 gene chips (n=9 chips) described previously [McMullen et al. 2004]. Microarrays were washed and stained with a streptavidin-bound marker and scanned. Data were analyzed with Affymetrix Microarray Suite 5.0 software. Only genes with consistent absent/present calls in all three independent replicates per group were considered for further analysis. Comparisons used the 6-mo transcriptome as the baseline and the one-sided Wilcoxonâs signed rank test to estimate âincrease/no change/ decreaseâ difference calls for each pair-wise comparison. Only difference calls consistent in all pair-wise comparisons and with average changes > 1.70 were considered significant, resulting in a conservative list of genes with changed expression levels. Functional classification of genes was based on an extensive literature review.

Project description:Background: MicroRNA (miRNA) is an emerging subclass of small non-coding RNAs that regulates gene expression and has a pivotal role for many physiological processes including cancer development. Recent reports revealed the role of miRNAs as ideal biomarkers and therapeutic targets due to their tissue- or disease-specific nature. Head and neck cancer (HNC) is a major cause of cancer-related mortality and morbidity, and laryngeal cancer has the highest incidence in it. However, the molecular mechanisms involved in laryngeal cancer development remain to be known and highly sensitive biomarkers and novel promising therapy is necessary. Methodology/Principal Findings: To explore laryngeal cancer-specific miRNAs, RNA from 5 laryngeal surgical specimens including cancer and non-cancer tissues were hybridized to microarray carrying 723 human miRNAs. The resultant differentially expressed miRNAs were further tested by using quantitative real time PCR (qRT-PCR) on 43 laryngeal tissue samples including cancers, noncancerous counterparts, benign diseases and precancerous dysplasias. Significant expressional differences between matched pairs were reproduced in miR-133b, miR-455-5p, and miR-196a, among which miR-196a being the most promising cancer biomarker as validated by qRT-PCR analyses on additional 84 tissue samples. Deep sequencing analysis revealed both quantitative and qualitative deviation of miR-196a isomiR expression in laryngeal cancer. In situ hybridization confirmed laryngeal cancer-specific expression of miR-196a in both cancer and cancer stroma cells. Finally, inhibition of miR-196a counteracted cancer cell proliferation in both laryngeal cancer-derived cells and mouse xenograft model. Conclusions/Significance: Our study provided the possibilities that miR-196a might be very useful in diagnosing and treating laryngeal cancer. To explore laryngeal cancer-specific miRNAs, RNA from 5 laryngeal surgical specimens including cancer and non-cancer tissues were hybridized to microarray carrying 723 human miRNAs. Total RNA including low molecular weight RNA from tissue samples was isolated using the mirVanaTM miRNA Isolation Kit (Ambion) according to the manufacturer's instructions. The quality of the RNA samples was assessed using an Agilent 2100 Bioanalyzer, and only the samples meeting the criteria of 28S/18S > 1 and RNA Integrity Number (RIN) M-bM-^IM-% 7.5 were used for all analyses. For microarray analysis, we used the Human miRNA Microarray Kit V2 (Agilent Technologies, Santa Clara, CA), which contains 20-40 features targeting each of 723 human miRNAs (Agilent design ID 019118) as annotated in the Sanger miRBase, release 10.1. Labeling and hybridization of total RNA samples were performed according to the manufacturer's protocol. One hundred ng of total RNA was used as an input into the labeling reaction, and the entire reaction was hybridized to each array for 20 hours at 55M-BM-0C. The results were analyzed using Agilent GeneSpring GX7.3. Normal controls and cancer samples were compared using Welch's t-test (p<0.05) and differentially expressed miRNAs with at least a 2-fold change in expression were considered to be potential biomarkers.

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Microarray Analysis Gene Expression Profiles in Laryngeal Muscle After Recurrent Laryngeal Nerve Injury

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