Abstract
A striking feature of microRNAs is that they are often clustered in the
genomes of animals. The functional and evolutionary consequences of this
clustering remain obscure. Here, we investigated a microRNA cluster
miR-6/5/4/286/3/309 that is conserved across drosophilid lineages. Small
RNA sequencing revealed expression of this microRNA cluster in Drosophila melanogaster
leg discs, and conditional overexpression of the whole cluster resulted
in leg appendage shortening. Transgenic overexpression lines expressing
different combinations of microRNA cluster members were also
constructed. Expression of individual microRNAs from the cluster
resulted in a normal wild-type phenotype, but either the expression of
several ancient microRNAs together (miR-5/4/286/3/309) or more recently
evolved clustered microRNAs (miR-6-1/2/3) can recapitulate the
phenotypes generated by the whole-cluster overexpression. Screening of
transgenic fly lines revealed down-regulation of leg patterning gene
cassettes in generation of the leg-shortening phenotype. Furthermore,
cell transfection with different combinations of microRNA cluster
members revealed a suite of downstream genes targeted by all cluster
members, as well as complements of targets that are unique for distinct
microRNAs. Considered together, the microRNA targets and the
evolutionary ages of each microRNA in the cluster demonstrates the
importance of microRNA clustering, where new members can reinforce and
modify the selection forces on both the cluster regulation and the gene
regulatory network of existing microRNAs.
Original language | English |
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Article number | msaa146 |
Pages (from-to) | 2955-2965 |
Journal | Molecular Biology and Evolution |
Volume | 37 |
Issue number | 10 |
Early online date | 10 Jun 2020 |
DOIs | |
Publication status | Published - Oct 2020 |