Figure 3.

Roles of Dicer partner proteins TRBP and PACT in miRNA biogenesis. (A) Correlation of strand selection behavior (scored as log〈5′ arm coverage/3′ arm coverage〉 among Ago2-associated miRNA) between WT MEF (X axis) and rescue conditions (Y axis) with either WT Dicer or Dicer_mut demonstrates the importance of TRBP and PACT in maintaining fidelity of strand selection. In the Dicer_mut condition, an increased deviation from the diagonal is observed due to impaired strand selection fidelity. Labels denote the 14 miRNA duplexes most dramatically affected (to >1 standard deviation) by the loss of TRBP and PACT recruitment to Dicer. 23 candidate duplexes varying in strand selection behavior by more than one standard deviation between MEF and WT rescue conditions (shown in grey) are not considered based on the possibility that they are behaving aberrantly due to the Dcr^-/- MEF context. The blue open circle represents miR-132. (B) Cluster analysis of miRNA lengths observed in WT MEF cells or Dicer knockout cells rescued with either WT Dicer or Dicer_mut, revealing an increased propensity for formation of 22 nt products instead of 21 nt products when Dicer can recruit TRBP and PACT for certain sensitive miRNAs (pink boxes). Ordering is based on results obtained in the WT Dicer rescue condition. See also Figure S3.