BRD2 and bacterial infectious disease: siRNAs, including heterochromatic siRNAs (hc-siRNAs), secondary siRNAs and natural antisense transcript siRNAs (NAT-siRNAs), are derived from Dicer-like (DCL)-catalyzed processing of double-stranded RNA (dsRNA) precursors.23 So far, siRNAs have been suggested to play roles in: (1) DNA methylation and chromatin modification mediated by hc-siRNAs,30 (2) repression of distinct mRNA targets by trans-acting siRNAs23,31,32,33 and (3) specific phenotypes, for example, proline accumulation,34 fertilization35 and bacterial infection,36 associated with NAT-siRNAs.