Novel FAM126A mutations in hypomyelination and congenital cataract disease

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Absence of Aquaporin-4 in Skeletal Muscle Alters Proteins Involved in Bioenergetic Pathways and Calcium Handling

Aquaporin-4 (AQP4) is a water channel expressed at the sarcolemma of fast-twitch skeletal muscle fibers, whose expression is altered in several forms of muscular dystrophies. However, little is known concerning the physiological role of AQP4 in skeletal muscle and its functional and structural interaction with skeletal muscle proteome. Using AQP4-null mice, we analyzed the effect of the absence of AQP4 on the morphology and protein composition of sarcolemma as well as on the whole skeletal muscle proteome. Immunofluorescence analysis showed that the absence of AQP4 did not perturb the expression and cellular localization of the dystrophin-glycoprotein complex proteins, aside from those belonging to the extracellular matrix, and no alteration was found in sarcolemma integrity by dye extravasation assay. With the use of a 2DE-approach (BN/SDS-PAGE), protein maps revealed that in quadriceps, out of 300 Coomassie-blue detected and matched spots, 19 proteins exhibited changed expression in AQP4−/− compared to WT mice. In particular, comparison of the protein profiles revealed 12 up- and 7 down-regulated protein spots in AQP4−/− muscle. Protein identification by MS revealed that the perturbed expression pattern belongs to proteins involved in energy metabolism (i.e. GAPDH, creatine kinase), as well as in Ca2+ handling (i.e. parvalbumin, SERCA1). Western blot analysis, performed on some significantly changed proteins, validated the 2D results. Together these findings suggest AQP4 as a novel determinant in the regulation of skeletal muscle metabolism and better define the role of this water channel in skeletal muscle physiology

Mitochondrial DNA deletion in a child with mitochondrial encephalomyopathy, growth hormone deficiency, and hypoparathyroidism.

We report an 11-year-old boy with short stature, bilateral ptosis, sensorineural hearing loss, muscle weakness, and endocrine abnormalities. Brain magnetic resonance imaging (MRI) showed a bilateral abnormal signal in the globus pallidus and in the midbrain tegment. Muscle biopsy specimens showed ragged red and cytochrome c oxidase negative fibers, and biochemical analysis of muscle homogenate showed a partial defect of complex I and IV activities of the respiratory chain enzymes. Analysis of mitochondrial DNA by a polymerase chain reaction screening procedure and Southern blot revealed a novel heteroplasmic single mitochondrial DNA deletion of 7.8 kb in different tissues. This deletion was absent in the blood DNA of his mother and brother. This case further expands and confirms the wide clinical spectrum of mitochondrial disorders associated with single large-scale mitochondrial DNA deletions

Lack of mutations in K-ras codons 12 and 13 in human atherosclerotic lesions.

In the framework of a project investigating the possible involvement of cancer biomarkers in human atherogenesis, we evaluated the occurrence of K-ras mutations in the DNA extracted from smooth muscle cells of abdominal aorta atherosclerotic lesions. The molecular analysis of the DNA from 32 surgical specimens, using PCR-based denaturing gradient gel electrophoresis (DGGE), did not reveal any variant in K-ras codons 12 and 13, which are the most frequently involved codons among the ras genes mutated in various types of human tumors. Analysis of the DNA extracted from four cell lines carrying known K-ras mutational alleles showed typically positive DGGE patterns. Thus, on the whole, the conclusions of this study and of previous studies using the same biological material are consistent with the occurrence of DNA adducts in human atherosclerotic lesions but in the absence of p53 involvement or of K-ras mutations in codons 12 and 13