Unknown,Transcriptomics,Genomics,Proteomics

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MicroRNA expression in the newborn mouse cochlea and vestibule

ABSTRACT: MicroRNAs (miRNAs) inhibit the translation of target mRNAs and affect, directly or indirectly, the expression of a large portion of the protein-coding genes. This study focuses on miRNAs that are expressed in the mouse cochlea and vestibule, the two inner ear compartments. To identify miRNAs that are expressed in the vertebrate developing inner ear, we used miRNA microarrays. Similar miRNA profiles were found in newborn (P0) mouse whole cochleae and vestibules. 105 miRNAs were found to be expressed in the whole P0 cochlea and 114 miRNAs expressed in the whole P0 vestibule with average intensities higher than twice the global background, out of 206 included in the arrays. Only 24 miRNAs were found to have different levels of expression in these whole organs, and these differences were mild (15-40%). The microarray results were intersected with two bioinformatic complementary approaches in order to choose candidate miRNAs that are predicted to be expressed specifically in the inner ear sensory epithelia (see the paper). Six small (<40 nt) RNA samples were hybridized with 4 microarrays (to save costs, some of the microarrays were hybridized with two different samples, labeled with different CyDyes â Cy3 and Cy5). Each RNA sample contains small RNAs (<40 nt) pooled from at least 20 newborn cochleae or vestibules, and there are 3 different samples for each organ. However, one of the samples (WT_P0_whole_Cochlea_3_V4) was hybridized with a different array than the other samples (printed from the same probes, but at a different date), and therefore excluded from the analysis described in the paper. Each microarray contains at least 4 identical spots per each probe that may be considered as technical replicates. Four of the samples were hybridized in parallel at the same day to two microarrays, and the dyes were swaped: First microarray: WT_P0_whole_Cochlea_1 (Cy3) [GSM388075] and WT_P0_whole_Vestibule_2 (Cy5) [GSM388635]; second microarray: WT_P0_whole_Cochlea_2 (Cy5) [GSM388633] and WT_P0_whole_Vestibule_1 (Cy3) [GSM388634]. The other 2 samples: WT_P0_whole_Vestibule_3 (Cy3) [GSM388637] and WT_P0_whole_Cochlea_3_V4 (Cy3) [GSM388660] were hybridized to two individual microarrays, at different dates. The miRNA profile in the cochlear and vestibular samples were compared: the vestibular samples are considered as the âexperimentâ samples, and the cochlear samples â as âreferenceâ. Positive control probes (labeled as âcontrol 1â in raw data) were added to RNA samples before labeling. The average of empty and buffer spots was used to calculate the global background of each array, and only miRNAs with an average expression higher than twice the fold of the array global background at least in one of the tissues were considered as expressed.

ORGANISM(S): Mus musculus

SUBMITTER: Eran Hornstein

PROVIDER: E-GEOD-15496 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

MicroRNAs are essential for development and function of inner ear hair cells in vertebrates.

Friedman Lilach M LM Dror Amiel A AA Mor Eyal E Tenne Tamar T Toren Ginat G Satoh Takunori T Biesemeier Deborah J DJ Shomron Noam N Fekete Donna M DM Hornstein Eran E Avraham Karen B KB

Proceedings of the National Academy of Sciences of the United States of America 20090428 19

MicroRNAs (miRNAs) inhibit the translation of target mRNAs and affect, directly or indirectly, the expression of a large portion of the protein-coding genes. This study focuses on miRNAs that are expressed in the mouse cochlea and vestibule, the 2 inner ear compartments. A conditional knock-out mouse for Dicer1 demonstrated that miRNAs are crucial for postnatal survival of functional hair cells of the inner ear. We identified miRNAs that have a role in the vertebrate developing inner ear by comb ...[more]

PMID: 19416898

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Project description:The inner ear in mammals is derived from a simple ectodermal thickening called the otic placode. Through a series of complex morphological changes, the placode forms the mature inner ear comprising of the auditory organ (cochlea) and the vestibular/balance organs (utricle, saccule, and three semi-circular canals). The vast majority of genes known to be involved during inner ear development have been found through mutational screens or by chance. To identify genes that can serve as novel candidates required for inner ear development, and also candidate genes for uncloned human deafnesses, inner ear tissues from mouse embryos from E9 to E15 were microdissected and expression-profiled at half-day intervals. Also profiled was the non-inner ear mesenchymal tissue surrounding the inner ear tissue. Various patterns of gene expression were identified, and significant biological pathways that these genes represented were identified. Also identified were mouse genes whose human orthologs are located within uncloned non-syndromic deafness intervals, thus serving as candidates for sequence analysis. Experiment Overall Design: Inner ear tissues from E9 to E15 were microdissected at half-day intervals. E9 is the earliest stage when the otic placode is clearly visible and able to be microdissected cleanly. E15 is the stage when all the organs of the inner ear have become established, as have the sensory hair and non-sensory support cells within those organs. For each of the stages from E9 to E10, whole inner ears were profiled. For each of the stages from E10.5 to E12, the primordial cochlear and vestibular organs were profiled separately. For each of the stages from E12.5 to E15, the cochlea and the saccule were profiled separately, whereas the utricle and the three ampullae were combined and profiled together. Any given tissue from any given stage was a collection of anywhere between 4 to 17 identical tissues, and was obtained in duplicate (i.e. from different litters). Hence, a total of 58 inner ear samples were obtained. Moreover, non-inner ear tissue found in the immediate vicinity of inner ear tissue was also obtained and profiled. Specifically, all non-inner ear tissue from E9 was profiled in duplicate. Non-inner ear tissue from E9.5 to E10.5 was pooled and profiled together (in duplicate), whereas that from E11 to E15 was pooled and profiled together (also in duplicate). Therefore, a total of 6 non-inner samples were obtained.

Project description:Objective: Otitis media is known to alter expression of cytokine and other genes in the mouse middle ear and inner ear. However, whole mouse genome studies of gene expression in otitis media have not previously been undertaken. Ninety-nine percent of mouse genes are shared in the human, so these studies are relevant to the human condition. Methods: To assess inflammation-driven processes in the mouse ear, gene chip analyses were conducted on mice treated with trans-tympanic heat-killed Hemophilus influenza using untreated mice as controls. Middle and inner ear tissues were separately harvested at 6 hours, RNA extracted, and samples for each treatment processed on the Affymetrix 430 2.0 Gene Chip for expression of its 34,000 genes. Results: Statistical analysis of gene expression compared to control mice showed significant alteration of gene expression in 2,355 genes, 11% of the genes tested and 8% of the mouse genome. Significant middle and inner ear upregulation (fold change >1.5, p<0.05) was seen in 1,081 and 599 genes respectively. Significant middle and inner ear downregulation (fold change <0.67, p<0.05) was seen in 978 and 287 genes respectively. While otitis media is widely believed to be an exclusively middle ear process with little impact on the inner ear, the inner ear changes noted in this study were numerous and discrete from the middle ear responses. This suggests that the inner ear does indeed respond to otitis media and that its response is a distinctive process. Numerous new genes, previously not studied, are found to be affected by inflammation in the ear. Conclusion: Whole genome analysis via gene chip allows simultaneous examination of expression of hundreds of gene families influenced by inflammation in the middle ear. Discovery of new gene families affected by inflammation may lead to new approaches to the study and treatment of otitis media. There are 8 control samples and 9 samples trans-tympanically injected with H flu 10e9 for 6 hours. Each sample is from a single animal.

Project description:Objective: Otitis media is known to alter expression of cytokine and other genes in the mouse middle ear and inner ear. However, whole mouse genome studies of gene expression in otitis media have not previously been undertaken. Ninety-nine percent of mouse genes are shared in the human, so these studies are relevant to the human condition. Methods: To assess inflammation-driven processes in the mouse ear, gene chip analyses were conducted on mice treated with trans-tympanic heat-killed Hemophilus influenza using untreated mice as controls. Middle and inner ear tissues were separately harvested at 6 hours, RNA extracted, and samples for each treatment processed on the Affymetrix 430 2.0 Gene Chip for expression of its 34,000 genes. Results: Statistical analysis of gene expression compared to control mice showed significant alteration of gene expression in 2,355 genes, 11% of the genes tested and 8% of the mouse genome. Significant middle and inner ear upregulation (fold change >1.5, p<0.05) was seen in 1,081 and 599 genes respectively. Significant middle and inner ear downregulation (fold change <0.67, p<0.05) was seen in 978 and 287 genes respectively. While otitis media is widely believed to be an exclusively middle ear process with little impact on the inner ear, the inner ear changes noted in this study were numerous and discrete from the middle ear responses. This suggests that the inner ear does indeed respond to otitis media and that its response is a distinctive process. Numerous new genes, previously not studied, are found to be affected by inflammation in the ear. Conclusion: Whole genome analysis via gene chip allows simultaneous examination of expression of hundreds of gene families influenced by inflammation in the middle ear. Discovery of new gene families affected by inflammation may lead to new approaches to the study and treatment of otitis media. There are 6 control samples and 8 samples trans-tympanically injected with H flu 10e9 for 6 hours. Each sample is a pool of 4 animals

Dataset Information

MicroRNA expression in the newborn mouse cochlea and vestibule

Publications

MicroRNAs are essential for development and function of inner ear hair cells in vertebrates.

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