Disease Phenotypes In A Mouse Model Of Rna Toxicity Are Independent Of Protein Kinase Ca And Protein Kinase C Beta

Myotonic dystrophy type 1(DM1) is the prototype for diseases caused by RNA toxicity. RNAs from the mutant allele contain an expanded (CUG)(n) tract within the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. The toxic RNAs affect the function of RNA binding proteins leading to sequestration of muscleblind-like (MBNL) proteins and increased levels of CELF1 (CUGBP, Elav-like family member 1). The mechanism for increased CELF1 is not very clear. One favored proposition is hyper-phosphorylation of CELF1 by Protein Kinase C alpha (PKC alpha) leading to increased CELF1 stability. However, most of the evidence supporting a role for PKC-alpha relies on pharmacological inhibition of PKC. To further investigate the role of PKCs in the pathogenesis of RNA toxicity, we generated transgenic mice with RNA toxicity that lacked both the PKC alpha and PKC beta isoforms. We find that these mice show similar disease progression as mice wildtype for the PKC isoforms. Additionally, the expression of CELF1 is also not affected by deficiency of PKC alpha and PKC beta in these RNA toxicity mice. These data suggest that disease phenotypes of these RNA toxicity mice are independent of PKC alpha and PKC beta.