Detection of a novel sense-antisense RNA-hybrid structure by RACE experiments on endogenous troponin I antisense RNA.
Conformational changes in the troponin/tropomyosin complex significantly alter the mechanical properties of cardiac muscle. Phosphorylation of cardiac troponin I, part of the troponin/tropomyosin complex, reduces calcium affinity, which leads to increased relaxation of cardiac muscle. Because cardiac troponin I plays a central role in tuning the heart to different work demands, detailed knowledge of troponin I protein regulation is required. Our group previously detected naturally occurring antisense RNA for troponin I in human and rat hearts, and here, attempt to unravel the structure of rat cardiac troponin I antisense RNA. We performed rapid amplification of cDNA ends (RACE) experiments and discovered antisense sequences identical to a copy of the sense mRNA, which led us to conclude that the antisense RNA must be transcribed from troponin I mRNA in the cytoplasm. Moreover, we isolated RNA structures comprising sense and antisense sequences in one continuous molecule. As we found no homolog structures described in the literature, we called this "hybrid RNA." Because a duplex formation was demonstrated previously we concluded that hybrid RNA is a consequence of a tight interaction between sense and antisense troponin I RNA in vivo, which we discuss in the article.
Bartsch
Holger
H
Medical Clinic I, Department of Cardiology, Humboldt-University (Charité), Ziegelstr. 5-9, D10117 Berlin, Germany.
Voigtsberger
Stefanie
S
Baumann
Gert
G
Morano
Ingo
I
Luther
Hans Peter
HP
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D005260:Female; D008969:Molecular Sequence Data; D021141:Nucleic Acid Amplification Techniques; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D016372:RNA, Antisense / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017422:Sequence Analysis, DNA; D017423:Sequence Analysis, RNA; D019210:Troponin I / Q000235:genetics*
D016372:RNA, Antisense; D012333:RNA, Messenger; D019210:Troponin I