Abstract

   Posttranslational arginylation mediated  by arginyltransferase (Ate1)
   is  essential  for  cardiovascular  development  and angiogenesis  in
   mammals  and  directly  affects  the  myocardium   structure  in  the
   developing heart.   We  recently  showed  that  arginylation exerts a
   number of intracellular effects by modifying proteins involved in the
   functioning of actin cytoskeleton and  the  events  of cell motility.
   Here we investigate the role of arginylation  in  the development and
   function of cardiac  myocytes  and  their actin-containing structures
   during  embryogenesis.   Biochemical  and  mass spectrometry analysis
   shows that alpha  cardiac  actin  undergoes  arginylation on multiple
   sites during development.  Ultrastructural analysis of the myofibrils
   in wild type and Ate1 knockout mouse hearts shows that the absence of
   arginylation results in  defects  in  myofibril  structure that delay
   their development and affect the continuity  of myofibrils throughout
   the heart, predicting defects  in  cardiac contractility.  Comparison
   of cardiac myocytes derived from wild  type  and  Ate1 knockout mouse
   embryos show that the  absence  of  arginylation  results in abnormal
   beating patterns.   Our  results  demonstrate cell-autonomous cardiac
   myocyte defects in arginylation  knockout  mice  that  lead to severe
   congenital abnormalities similar to those observed  in human disease,
   and outline a new function of arginylation in the regulation of actin
   cytoskeleton in cardiac myocytes.

   (Development, Vol~135(23), Page 3881-3889, doi:10.1242/dev.022723, 2008)