SnoRNAs may accelerate protein synthesis for the rapid growth of the regenerating tail blastema in the lizard Podarcis muralis

Tail regeneration in lizards derives from the formation of a regenerative blastema. Numerous snoRNAs exclusively up-regulated in the regenerating tail but absent in the scarring limb of the lizard Podarcis muralis have been detected suggesting they are key genes for regeneration. While most snord-, snora- and scarna-RNAs are activators of protein synthesis and cell proliferation (oncogenes) some may also be tumour suppressors. A tail blastema of 2–3 mm in length consists of proliferating mesenchymal cells, fibroblasts and keratinocytes with active nucleoli, rosette-patterned ribosomes and few rough endoplasmic cisternae. In few days, the blastema grows into a new tail indicating intense protein synthesis within this short period. A quantitative RT-PCR analysis of snord87, snord26, snord74, snora63, scarna11, U2 and U4 shows that, aside snord87, the other ncRNAs are up-regulated, particularly, U2, U4 and scarna11. These ncRNAs might regulate the rate of production of ribosomes from the nucleolus (snora- and snord-RNAs), the splicing process (snord- and scarna-RNAs, U2 and U4), the speed of protein synthesis (snora- and snord-RNAs) and cell proliferation in the blastema. These non-coding-RNAs are hypothesized to intensify the production of more functional ribosomes that accelerate the rate of protein synthesis and rapid growth of the blastema into a new tail.