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Inherited fatty acid oxidation diseases in their mild forms often present as metabolic myopathies. Carnitine Palmitoyl Transferase 2 (CPT2) deficiency, one such prototypical disorder is associated with compromised myotube differentiation. Here, we show that CPT2-deficient myotubes exhibit defects in focal adhesions and redox balance, exemplified by increased SOD2 expression. We document unprecedented alterations in the cellular prion protein PrPC, which directly arise from the failure in CPT2 enzymatic activity. We also demonstrate that the loss of PrPC function in normal myotubes recapitulates the defects in focal adhesion, redox balance and differentiation hallmarks monitored in CPT2-deficient cells. These results are further corroborated by studies performed in muscles from Prnp−/− mice. Altogether, our results unveil a molecular scenario, whereby PrPC dysfunction governed by faulty CPT2 activity may drive aberrant focal adhesion turnover and hinder proper myotube differentiation. Our study adds a novel facet to the involvement of PrPC in diverse physiopathological situations. [ABSTRACT FROM AUTHOR]

Carnitine palmitoyltransferase 1A (CPT1A) deficiency is a rare autosomal recessive disorder of mitochondrial fatty acid oxidation. CPT1 controls the import of long-chain fatty acids into the mitochondria, where they are oxidized. Two CPT1 isoforms, the so-called "liver" and "muscle" CPT1s encoded by the CPT1A and CPT1B genes, respectively, have been identified so far. While the cDNA sequences of both isoforms are known, only CPT1B gene organization has yet been described. We took advantage of the working draft data to characterize the organization of the human CPT1A gene. We have shown the existence of 20 exons, spanning 60 kb of DNA. Two alternate promoters and numerous transcription factor-binding sites were identified within the 5′ upstream region of the gene. In the 3′ untranslated region, the major polyA signal was suggested to lie about 2 kb downstream of the stop codon. These data enabled us to characterize six novel mutations in four CPT1A-deficient patients; namely Q100X (exon 4), A414 V (exon 11), Y498C (exon 13), 1876-1G>A (intron 15), a 113-bp intronic insertion in the mature CPT1A mRNA (exon 13–14 junction), and a large 8-kb deletion encompassing intron 14 to exon 17. Thus, identification of the CPT1A gene organization contributes to improve the molecular screening in patients and provides tools for the study of the human CPT1A gene expression. [ABSTRACT FROM AUTHOR]

Studying consanguineous families with Ghosal hematodiaphyseal dysplasia syndrome (GHDD), a disorder of increased bone density, we identified mutations in TBXAS1, which encodes thromboxane synthase (TXAS). TXAS, an enzyme of the arachidonic acid cascade, produces thromboxane A2 (TXA2). Platelets from subjects with GHDD showed a specific deficit in arachidonic acid–produced aggregation. We also found that TXAS and TXA2 modulated expression of TNFSF11 and TNFRSF11B (encoding RANKL and osteoprotegerin (OPG), respectively) in primary cultured osteoblasts. [ABSTRACT FROM AUTHOR]