Overexpression of myotonic dystrophy protein kinase in C2C12 myogenic culture involved in the expression of ferritin heavy chain and interleukin-1alpha mRNAs

Deep proteomics of mouse skeletal muscle enables quantitation of protein isoforms, metabolic pathways, and transcription factors

Skeletal muscle constitutes 40% of individual body mass and plays vital roles in locomotion and whole-body metabolism. Proteomics of skeletal muscle is challenging because of highly abundant contractile proteins that interfere with detection of regulatory proteins. Using a state-of-the art MS workflow and a strategy to map identifications from the C2C12 cell line model to tissues, we identified a total of 10,218 proteins, including skeletal muscle specific transcription factors like myod1 and myogenin and circadian clock proteins. We obtain absolute abundances for proteins expressed in a muscle cell line and skeletal muscle, which should serve as a valuable resource. Quantitation of protein isoforms of glucose uptake signaling pathways and in glucose and lipid metabolic pathways provides a detailed metabolic map of the cell line compared with tissue. This revealed unexpectedly complex regulation of AMP-activated protein kinase and insulin signaling in muscle tissue at the level of enzyme isoforms.

Transcranial sonography in patients with myotonic dystrophy type 1

INTRODUCTION

In this study we analyzed transcranial sonography (TCS) in patients with myotonic dystrophy type 1 (DM1).

METHODS

This cross-sectional study included 66 DM1 patients and 55 matched healthy controls (HCs). Echogenicity of the brainstem raphe (BR) and substantia nigra (SN) and third ventricle width (DTV) were assessed by TCS.

RESULTS

BR hypoechogenicity was more common in DM1 patients than in HCs (37.7% vs. 7.8%, P < 0.01). Patients with depression or fatigue were more likely to have BR hypoechogenicity (80.0% vs. 29.4%, P < 0.01 and 51.9% vs. 24.2%, P < 0.05, respectively). Both hypoechogenicity and hyperechogenicity of SN were more frequent in DM1 patients than in controls (26.2% vs. 10.9% and 13.1% vs. 1.8%, respectively, P < 0.01). DTV was increased in DM1 patients compared with HCs (6.0 ± 1.4 vs. 4.9 ± 0.9 mm, P < 0.01).

CONCLUSION

TCS can offer new insight into structural changes of several cerebral areas in patients with DM1.

Altered expression of CUG binding protein 1 mRNA in myotonic dystrophy 1: possible RNA–RNA interaction

The triplet repeats mutation, which causes myotonic dystrophy 1 (DM1), is thought to have a dominant negative effect on RNA levels. In light of previous results using differential display analysis, the present study focused on the expression of CUG binding protein 1 (CUGBP1) mRNA. Northern blot analysis demonstrated that the quantity of CUGBP1 mRNA in three DM1 patients was approximately 70% of that observed in three normal controls (P < 0.05). In addition, a semi-quantitative RT-PCR assay showed that the relative amount of CUGBP1 mRNA was reduced in muscle biopsy samples from 10 DM1 patients compared to that from five normal individuals (P < 0.01) and 10 myopathic disease controls (P < 0.01). The amount of CUGBP1 mRNA was negatively correlated with the size of the CTG expansion (r = -0.85, P < 0.05). In vitro RNA-RNA binding experiments demonstrated that the incubation of expanded CUG repeats with CUGBP1 RNA generated a higher molecular weight band, which was digested by RNase III. The CUGBP1 mRNA was found to contain several CAG repeat sequences. These results suggest that the CUG expansion may bind to complementary sequences within the CUGBP1 mRNA and that this molecular interaction may affect CUGBP1 mRNA expression in DM1.