Small Cajal body-specific RNA 2 (scaRNA2)

Small Cajal body-specific RNA 2 (scaRNA2) is a non-coding RNA molecule localized primarily in the Cajal bodies of the nucleus, with additional chromatin association[1][2]. It is 420 nucleotides long in humans and is highly conserved across evolution[1]. ScaRNA2 acts as a guide RNA for the site-specific 2'-O-methylation of U2 small nuclear RNA (snRNA), specifically at residues 25 and 61, a chemical modification essential for the maturation and function of spliceosomal snRNAs[1][2][4]. Uniquely, scaRNA2 has been identified as a regulator of DNA repair pathway choice: it localizes to DNA double-strand breaks and, by binding to and inhibiting DNA-dependent protein kinase (DNA-PKcs), promotes homologous recombination (HR) repair while suppressing non-homologous end joining (NHEJ)[1]. This regulatory role implicates scaRNA2 in the maintenance of genomic stability[1]. ScaRNA2 does not encode a protein and is not considered a classical therapeutic target such as a receptor, enzyme, or transporter; instead, it exerts its biological effects as a structural and regulatory RNA within nuclear ribonucleoprotein complexes[1][2][4].

Other names

mgU2-25/61SCARNA2