Project description:Purpose: To examine and characterize the expression profile of genes expressed at the neuromuscular junctions (NMJs) of extraocular muscles (EOMs) in comparison to the NMJs of tibialis anterior muscle (TA). Methods: Adult rat rectus EOMs and TAs were dissected, flash-frozen, serially sectioned and stained for acetylcholinesterase to identify NMJs. Approximately 6000 NMJs for EOM (EOMsyn) and 6000 NMJs for TA (TAsyn) and equal amounts of NMJ-free fiber regions (EOMfib, TAfib) and underlying myonuclei were captured using laser capture microdissection (LCM). RNA was isolated, processed and used for microarray-based expression profiling. Profiles were generated for genes differentially expressed at synaptic and non-synaptic regions of TA (TAsyn vs TAfib) and EOM (EOMsyn vs EOMfib) using a false discovery rate (FDR) of 5% as well as an 'interaction list' revealing the most significantly differentially expressed genes at an FDR of 1%. We validated the profiles by real-time quantitative reverse transcription-polymerase chain reaction (qPCR). Results: The regional transcriptomes associated with NMJ of EOMs and TAs were identified. We found 275 genes that were preferentially expressed in EOMsyn and 230 known transcripts that were preferentially expressed in TAsyn; 288 of the transcripts were common to both synapses; these included well-known, evolutionarily conserved, synaptic markers (e.g. nicotinic Acetylcholine receptor (ACHR) alpha and epsilon subunits, nestin) as well as a large number of novel genes. Conclusion: Transcriptome level differences exist between EOM synaptic regions and TA synaptic regions. Our definition of the synaptic transcriptome provides insight into the mechanism of formation and functioning of the unique synapses of EOM and their differential involvement in diseases noted in the EOM allotype. Tissue preparation: A total of 4 rats were killed by CO2 inhalation. The bony orbit was removed from the skull and opened at the lamina cribrosa. The globe with the four recti EOMs still attached was carefully dissected from the bony orbit. The eyeball with muscles was placed on cryomolds, covered with OCT tissue embedding medium (Tissue-Tek: Sakura Finetek, Tokyo, Japan) and flash-frozen in isopentane, cooled in liquid nitrogen and stored at -80 degreeC. The tibialis anterior (TA) muscles of all rats were dissected and frozen in the same way. The EOM and TA were then cut transversely into 10 um sections using a Microm HM 500 cryostat (Zeiss, Oberkochen, Germany), mounted on PEN (poly-ethylene-naphthalene) Membrane Slides (Arcturus) and refrozen immediately. Unfixed sections were stored at -80 degreeC until needed. Section staining: Sections for LCM were stained for acetylcholinesterase based on the method of Karnowsky and Roots to visualize NMJ. Palm microdissection: The PALM MicroBeam System was used for microdissection and for catapulting isolated tissue into a microfuge cap containing 80 ul RLT-Lysis Buffer (Quiagen). Approximately 1000 NMJ and equal amount of non-synaptic regions were collected for each muscle.
Project description:Purpose: To examine and characterize the expression profile of genes expressed at the neuromuscular junctions (NMJs) of extraocular muscles (EOMs) in comparison to the NMJs of tibialis anterior muscle (TA). Methods: Adult rat rectus EOMs and TAs were dissected, flash-frozen, serially sectioned and stained for acetylcholinesterase to identify NMJs. Approximately 6000 NMJs for EOM (EOMsyn) and 6000 NMJs for TA (TAsyn) and equal amounts of NMJ-free fiber regions (EOMfib, TAfib) and underlying myonuclei were captured using laser capture microdissection (LCM). RNA was isolated, processed and used for microarray-based expression profiling. Profiles were generated for genes differentially expressed at synaptic and non-synaptic regions of TA (TAsyn vs TAfib) and EOM (EOMsyn vs EOMfib) using a false discovery rate (FDR) of 5% as well as an “interaction list” revealing the most significantly differentially expressed genes at an FDR of 1%. We validated the profiles by real-time quantitative reverse transcription-polymerase chain reaction (qPCR). Results: The regional transcriptomes associated with NMJ of EOMs and TAs were identified. We found 275 genes that were preferentially expressed in EOMsyn and 230 known transcripts that were preferentially expressed in TAsyn; 288 of the transcripts were common to both synapses; these included well-known, evolutionarily conserved, synaptic markers (e.g. nicotinic Acetylcholine receptor (ACHR) alpha and epsilon subunits, nestin) as well as a large number of novel genes. Conclusion: Transcriptome level differences exist between EOM synaptic regions and TA synaptic regions. Our definition of the synaptic transcriptome provides insight into the mechanism of formation and functioning of the unique synapses of EOM and their differential involvement in diseases noted in the EOM allotype.
Project description:PURPOSE: Infantile nystagmus syndrome (INS) is a gaze-holding disorder characterized by conjugate, uncontrolled eye oscillations that can result in significant visual acuity loss. INS is often associated with albinism, but the mechanism is unclear. Albino mice have nystagmus; however, a pigmented mouse with a tyr mutation making it phenotypically albino, the B6(CG)-Tyr(c-2J)/J (B6 albino), had not been tested. We tested optokinetic nystagmus reflexes (OKN) in B6 albino and control mice. RNA-Seq was performed on extraocular muscles (EOM), tibialis anterior muscle (TA), abducens (CN6), and oculomotor (CN3) neurons to uncover molecular differences that could account for nystagmus.
Project description:The extraocular muscles (EOM) are anatomically and physiologically distinct from other skeletal muscles. EOM are preferentially affected in mitochondrial myopathies, but spared in Duchenne's muscular dystrophy. The anatomical and pathophysiological properties of EOM have been attributed to their unique molecular makeup: an allotype. We used expression profiling to define molecular features of the EOM allotype. We found 346 differentially expressed genes in rat EOM compared with tibialis anterior, based on a twofold difference cutoff. Genes required for efficient, fatigue-resistant, oxidative metabolism were increased in EOM, whereas genes for glycogen metabolism were decreased. EOM also showed increased expression of genes related to structural components of EOM such as vessels, nerves, mitochondria, and neuromuscular junctions. Additionally, genes related to specialized functional roles of EOM such as the embryonic and EOM-specific myosin heavy chains and genes for muscle growth, development, and/or regeneration were increased. The EOM expression profile was validated using biochemical, structural, and molecular methods. Characterization of the EOM expression profile begins to define gene transcription patterns associated with the unique anatomical, metabolic, and pathophysiological properties of EOM.
Project description:The extraocular muscles (EOMs) are a unique group of muscles that are anatomically and physiologically distinct from other skeletal muscles. Previously, we and others have shown that EOMs have a unique transcriptome and proteome. Here, we investigated the expression pattern of microRNAs (miRNAs) in EOM, as they may play a role in generating the unique EOM allotype. We screened LC Sciences miRNA microarrays covering the sequences of miRBase 10.0 to define the microRNAome of normal mouse EOM and tibialis anterior (TA) limb muscle. 74 miRNAs were found to be differentially regulated (p-value < 0.05) and 31 miRNAs (14 up-regulated and 17 down-regulated) were found to be differentially regulated at a signal strength > 500 including the muscle-specific miR-206, miR-1, miR-133a, miR-133b and miR-499. qPCR analysis was used to validate the differential expression. Bioinformatic tools were used to identify potential miRNA-mRNA-protein interactions and integrate data with previous transcriptome and proteomic profiling data. Luciferase assays using co-transfection of precursor miRNAs (pre-miRNAs) along with reporter constructs containing the 3â-untranslated region (3âUTR) of their predicted target genes were used to validate targeting by identified miRNAs. The definition of the EOM microRNAome complements existing transcriptome and proteome data about the molecular make-up of EOM and provides further insight into regulation of muscle genes. These data will also help to further explain the unique EOM muscle allotype and its differential sensitivity to diseases such as Duchenne's muscular dystrophy (DMD) and may assist in development of therapeutic strategies. Total RNA from four EOM and four TA tissue samples dissected from four adult male C57/Bl10 mice were used (TA served as control) to screen four LC Sciences microRNA Microarray chips. The chips contained microRNA sequences based on miRBase content 10.0 totalling 568 different miRNAs. Samples were labelled with Cy3 and Cy5 using dye-swap. Relative differences of miRNA expression was expressed as fold-changes EOM/TA, which were calculated after normalization across all four arrays.
Project description:The extraocular muscles (EOM) are anatomically and physiologically distinct from other skeletal muscles. EOM are preferentially affected in mitochondrial myopathies, but spared in Duchenne's muscular dystrophy. The anatomical and pathophysiological properties of EOM have been attributed to their unique molecular makeup: an allotype. We used expression profiling to define molecular features of the EOM allotype. We found 346 differentially expressed genes in rat EOM compared with tibialis anterior, based on a twofold difference cutoff. Genes required for efficient, fatigue-resistant, oxidative metabolism were increased in EOM, whereas genes for glycogen metabolism were decreased. EOM also showed increased expression of genes related to structural components of EOM such as vessels, nerves, mitochondria, and neuromuscular junctions. Additionally, genes related to specialized functional roles of EOM such as the embryonic and EOM-specific myosin heavy chains and genes for muscle growth, development, and/or regeneration were increased. The EOM expression profile was validated using biochemical, structural, and molecular methods. Characterization of the EOM expression profile begins to define gene transcription patterns associated with the unique anatomical, metabolic, and pathophysiological properties of EOM. Keywords: other
Project description:The extraocular muscles (EOMs) are a unique group of muscles that are anatomically and physiologically distinct from other skeletal muscles. Previously, we and others have shown that EOMs have a unique transcriptome and proteome. Here, we investigated the expression pattern of microRNAs (miRNAs) in EOM, as they may play a role in generating the unique EOM allotype. We screened LC Sciences miRNA microarrays covering the sequences of miRBase 10.0 to define the microRNAome of normal mouse EOM and tibialis anterior (TA) limb muscle. 74 miRNAs were found to be differentially regulated (p-value < 0.05) and 31 miRNAs (14 up-regulated and 17 down-regulated) were found to be differentially regulated at a signal strength > 500 including the muscle-specific miR-206, miR-1, miR-133a, miR-133b and miR-499. qPCR analysis was used to validate the differential expression. Bioinformatic tools were used to identify potential miRNA-mRNA-protein interactions and integrate data with previous transcriptome and proteomic profiling data. Luciferase assays using co-transfection of precursor miRNAs (pre-miRNAs) along with reporter constructs containing the 3’-untranslated region (3’UTR) of their predicted target genes were used to validate targeting by identified miRNAs. The definition of the EOM microRNAome complements existing transcriptome and proteome data about the molecular make-up of EOM and provides further insight into regulation of muscle genes. These data will also help to further explain the unique EOM muscle allotype and its differential sensitivity to diseases such as Duchenne's muscular dystrophy (DMD) and may assist in development of therapeutic strategies.
Project description:Analysis of tibialis anterior (TA) muscle isolated from wildtype (WT) and Mettl21e deletion mice (KO). Results provide unbiased gene expression profile of TA muscle after Mettl21e deletion.
Project description:Evaluation of extraocular muscle (EOM) critical period by expression profiling in dark reared rat. Data form part of publication: Investigative Ophthalmology and Visual Sciences 44: 3842-3855, 2003. Keywords: other