Important Considerations for Evaluating the Data Presented by Igarashi et al

Abstract

To The Editor: The major conclusion drawn in the article by Igarashi et al,1 that cholesteryl ester hydrolase (gene symbol CES1) does not contribute to neutral cholesterol ester (CE) hydrolase activity, is based on the inability of the authors to detect CE hydrolase activity associated with the cDNA clone that they obtained by PCR amplification and by the inability of the authors to demonstrate change in intracellular CE hydrolytic activity by short hairpin (sh)RNA-mediated knockdown of CES1. The authors have not provided the sequence of the clone obtained and do not unequivocally show its identity to the reported CES1 with established role not only in intracellular CE hydrolysis,2 mobilization,3 and cholesterol efflux4 but also in attenuation of diet-induced atherosclerosis and lesion necrosis.5 It is noteworthy that the sense primer used in this study also shows a 95% homology to human CES4 (17/18 bp match; accession no. NR_003276). Single amino …