Serum stress responsive gene EhslncRNA of Entamoeba histolytica is a novel long noncoding RNA

Non coding RNAs are known to play important roles in regulating gene expression at the transcriptional and posttranscriptional levels in metazoans. There is very little information available about non coding RNAs in protists such as Entamoeba histolytica. Antisense and micro RNAs have been reported in E. histolytica, however no long non coding RNAs has been reported yet. Here, we report our findings on an in vitro serum stress-inducible gene EhslncRNA, a member of B1 transmembrane kinase family of E. histolytica. EhslncRNA encodes a transcript of 2.6 kb and sequence analysis revealed that there is no ORF >150 bp within this transcript. The transcript was found to be polyadenylated and mainly associated with monosomes in the cytoplasm under serum starvation. In normal proliferating cells this RNA is mainly present in the nucleus. The promoter element was mapped between 437 to 346 nucleotides upstream of transcriptional start site and has both positive and negative regulatory elements. Deletion of the negative element converted the promoter to serum inducible type. Oxygen and heat stress also increased expression levels of EhslncRNA. These observations suggest that EhslncRNA may be a long non coding RNA and likely to help cells withstand stressful conditions in the host.