IDENTIFYING NATURAL ANTISENSE TRANSCRIPTS OF CHOLESTEROL TRANSPORT RELATED PROTEINS

F. CASTILLO; U. ORLANDO; R. CASTILLA; P. MELE; E.J. PODESTÁ

Mar del Plata

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Natural Antisense Transcripts (NATs) are endogenous RNAs complementary to sense mRNAs. Several NATs regulate the expression of their sense counterparts at many levels of gene expression (transcription, maturation, transport, stability and translation). Since a fine regulation of gene expression and protein synthesis is needed for steroid synthesis, NATs could play a role in the control of the process. The aim of this study was to evaluate the existence of NATs for three proteins involved in cholesterol transport into the mitochondria, the rate-limiting step of steroid synthesis: Steroidogenic acute regulatory protein (StAR), acyl-CoA thioesterase (Acot2) and acyl-CoA synthetase 4 (ACS4). Total RNA of MA10 mouse Leydig cells was examined for NATs using a Rapid Amplification of cDNA Ends method and nested PCR. Several NATs were identified and sequenced. Their existence was verified by RT-PCR and Ribonuclease Protection Assay. We sought to evaluate the hormonal regulation of StAR NAT. A temporal hormone–dependent increase in the expression of StAR antisense transcript was observed in MA10 cells incubated with 8Br-cAMP or hCG by semiquantitative RT-PCR. Here we demonstrate the presence of NATs of StAR, Acot2 and ACS4 and the hormonal regulation of StAR NAT. These findings will help to understand the role of NATs in molecular mechanisms of gene expression and protein synthesis.