It implies an overlap existence in the ancestral genome. In reference [34], conducting a study with pseudogenes raised evidence in favor of selective pressure acting on duplicated selleck Belinostat genes and their cis-NATs/trans-NATs in specific regions of the Hominoidea genealogy chromosomes. Thus, across species, hundreds of transcribed sense/antisense sequences were probably preserved. It means that they kept the same pattern of overlap and indicates that these transcripts have conserved in vivo functions [35]. Likewise, further studies on the origins and mechanisms of regulation, in plants, can use preserved sense/antisense pairs [13]. However, to date, only the report of Wang et al. [13] presents data concerning their conservation in plants (Arabidopsis and rice).4.
NAT Coding CapacityBoth transcripts (sense and antisense) from a NAT locus may present a coding capacity or not [16]. However, according to Katayama et al. [12] in mammalian genomes the most common form of interaction between these two molecules is the existence of a sense transcript with coding capacity, interacting with an antisense transcript without the same informational ability. There are some evidence that noncoding RNAs have functionality, even though no coding capacity was associated to them [36]. Ponjavic et al. [36] conducted an evolution study on a set of mouse noncoding RNAs (macroRNAs), comparing their sequences and promoters with human and rat orthologous sequences, under three independent signatures of purifying selection, including substitutions, sequence insertions and deletions, and splicing.
They pointed that the evolution of that set of noncoding RNAs was not consistent with neutralist explanations. Additionally, according to Jouannet and Crespi [16], noncoding NATs have reduced the sequence conservation when compared to its coding counterpart.In plants, NAT coding capacity seems to be different. In rice, 86% of the NAT pairs have coding sequence regions in both transcripts [24]. In turn, 82% (1,402 of 1,710) of the predicted Arabidopsis NAT pairs encode for two protein-coding transcripts [37].5. NATs Pairs ExpressionSome studies have suggested that cis-NAT expression is a transcriptional noise while others claim that such expression is functional. Ling et al. [38] analyzed cis-NAT expressions in different tissues and species (human colon, mouse, and rat embryos) in order to settle this impasse.
Their assumption GSK-3 was that if orthologous cis-NATs showed similar expression patterns when compared with permuted cis-NAT pairs, it would provide evidence that cis-NATs are actively regulated or subjected to selective pressure. Moreover, the absence of such conservation could favor the transcriptional noise theory. The authors found that the expression patterns of many antisense transcripts are conserved across species.