title: Identifier (ID) elements are not preferentially located to brain-specific genes: high ID element representation in other tissue-specific- and housekeeping genes of the rat.
abstract: BC1 is a short non-coding RNA from rodents, which is transcribed by RNA pol III. Its RNA is highly abundant in the brain, where it exerts a post-transcriptional regulatory role in dendrites. Upon transcription, retroposition and insertion, BC1 gives rise to a subclass of short interspersed repetitive sequences (SINEs) named identifier (ID) elements. IDs can become integrated inside non-coding regions of RNA pol II transcription units, and - although challenged by a couple of reports - their preferential location to brain-specific genes has been long proposed. Furthermore, an additional, cis-regulatory role in the control of brain-specific pol II-directed transcripts has been suggested for these sequences. In this work we used Northern blot and in silico analyses to examine IDs' location among pol II transcription units in different tissues, and in housekeeping genes. ID sequences appeared distributed in a similar fashion within tissue-specific hnRNA populations of the brain, testis and liver, and within housekeeping primary transcripts as well. Moreover, when the lengths of the unprocessed transcripts were considered, ID representation was higher in housekeeping ones. On the other hand, ID elements appeared similarly distributed among the different gene regions, with the obvious exclusion of those sequences where strict constraints for proper gene expression exist. Altogether, the widespread distribution of ID elements in all the analyzed genes - including housekeeping - and in all gene regions, suggests a random location, raising questions about the specific cis-regulatory role of those sequences.
authors.affiliation: Departamento de Biología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Avda. Italia 3318, 11600 Montevideo, Uruguay. Electronic address: andygolds@hotmail.com.
authors.forename: Andrés
authors.initials: A
authors.lastname: Goldman
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Capoano
authors.forename: Evangelina
authors.initials: E
authors.lastname: González-López
authors.forename: Adriana
authors.initials: A
authors.lastname: Geisinger
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism*; D020043:Genes, Essential; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats
chemical_list: D012333:RNA, Messenger
keywords: BC1; ID; Identifier element; PABP; Rat genome; Repetitive DNA; SINE; eIF4A; eukaryotic initiation factor 4A; heterogeneous nuclear RNA; hnRNA; identifier; pol; poly-A binding protein; polymerase; primary transcript(s); pt(s); short interspersed nuclear element