RT Journal Article SR Electronic T1 Makorin 1 controls embryonic patterning by alleviating Bruno-mediated repression of oskar translation JF bioRxiv FD Cold Spring Harbor Laboratory SP 501643 DO 10.1101/501643 A1 Annabelle Dold A1 Hong Han A1 Niankun Liu A1 Andrea Hildebrandt A1 Mirko Brüggemann A1 Cornelia Rücklé A1 Anke Busch A1 Petra Beli A1 Kathi Zarnack A1 Julian König A1 Jean-Yves Roignant A1 Paul Lasko YR 2018 UL http://biorxiv.org/content/early/2018/12/22/501643.abstract AB Makorins are evolutionary conserved proteins that contain C3H-type zinc finger modules and a RING E3 ubiquitin ligase domain. In Drosophila maternal Makorin 1 (Mkrn1) has been linked to embryonic patterning and germ cell specification. Here, we show that Mkrn1 is required for translational activation of oskar, whose product is critical for axis specification and germ plasm assembly. We demonstrate that Mkrn1 interacts with poly(A) binding protein (pAbp) and binds osk 3’ UTR in a region adjacent to A-rich sequences. This binding site also overlaps with Bruno (Bru) responsive elements (BREs), which regulate osk translation. We observe increased association of the translational repressor Bru with osk mRNA upon depletion of Mkrn1, implying that the two proteins compete for osk binding. Consistently, reducing Bru dosage partially rescues viability and Osk protein level in ovaries from Mkrn1 females. We conclude that Mkrn1 controls embryonic patterning and germ cell formation by specifically activating osk translation via displacing Bru from its 3’ UTR.