TY - JOUR T1 - Makorin 1 controls embryonic patterning by alleviating Bruno-mediated repression of <em>oskar</em> translation JF - bioRxiv DO - 10.1101/501643 SP - 501643 AU - Annabelle Dold AU - Hong Han AU - Niankun Liu AU - Andrea Hildebrandt AU - Mirko Brüggemann AU - Cornelia Rücklé AU - Anke Busch AU - Petra Beli AU - Kathi Zarnack AU - Julian König AU - Jean-Yves Roignant AU - Paul Lasko Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/12/22/501643.abstract N2 - 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. ER -