Genomic profiling reveals Pitx2 controls expression of mature extraocular muscle contraction-related genes.

ABSTRACT: PURPOSE:To assess the influence of the Pitx2 transcription factor on the global gene expression profile of extraocular muscle (EOM) of mice. METHODS:Mice with a conditional knockout of Pitx2, designated Pitx2(?flox/?flox) and their control littermates Pitx2(flox/flox), were used. RNA was isolated from EOM obtained at 3, 6, and 12 weeks of age and processed for microarray-based profiling. Pairwise comparisons were performed between mice of the same age and differentially expressed gene lists were generated. Select genes from the profile were validated using real-time quantitative polymerase chain reaction and protein immunoblot. Ultrastructural analysis was performed to evaluate EOM sarcomeric structure. RESULTS:The number of differentially expressed genes was relatively small. Eleven upregulated and 23 downregulated transcripts were identified common to all three age groups in the Pitx2-deficient extraocular muscle compared with littermate controls. These fell into a range of categories including muscle-specific structural genes, transcription factors, and ion channels. The differentially expressed genes were primarily related to muscle contraction. We verified by protein and ultrastructural analysis that myomesin 2 was expressed in the Pitx2-deficient mice, and this was associated with development of M lines evident in their orbital region. CONCLUSIONS:The global transcript expression analysis uncovered that Pitx2 primarily regulates a relatively select number of genes associated with muscle contraction. Pitx2 loss led to the development of M line structures, a feature more typical of other skeletal muscle.

SUBMITTER: Zhou Y 

PROVIDER: S-EPMC3995565 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature