Short internal open reading frames repress the translation of N-terminally truncated proteoforms.

Internal translation initiation sites, as revealed by ribosome profiling experiments can potentially drive the translation of many N-terminally truncated proteoforms. We report that internal short open reading frame (sORF) within coding sequences regulate their translation. nTRIP6 represents a short nuclear proteoform of the cytoplasmic protein TRIP6.

The LIM domain protein nTRIP6 modulates the dynamics of myogenic differentiation.

The process of myogenesis which operates during skeletal muscle regeneration involves the activation of muscle stem cells, the so-called satellite cells. These then give rise to proliferating progenitors, the myoblasts which subsequently exit the cell cycle and differentiate into committed precursors, the myocytes. Ultimately, the fusion of myocytes leads to myofiber formation.

The LIM domain protein nTRIP6 acts as a co-repressor for the transcription factor MEF2C in myoblasts.

The transcription factor Myocyte enhancer factor 2C (MEF2C) plays a key role in the late differentiation of skeletal muscle progenitor cells, the so-called myoblasts. During myoblast differentiation, both MEF2C expression and transcriptional activity are regulated. We have reported that nTRIP6, the nuclear isoform of the focal adhesion LIM domain protein TRIP6, acts as an adaptor transcriptional co-activator for several transcription factors.

The LIM domain protein nTRIP6 recruits the mediator complex to AP-1-regulated promoters.

Several LIM domain proteins regulate transcription. They are thought to act through their LIM protein-protein interaction domains as adaptors for the recruitment of transcriptional co-regulators. An intriguing example is nTRIP6, the nuclear isoform of the focal adhesion protein TRIP6.