The F-actin-microtubule crosslinker Shot is a platform for Krasavietz-mediated translational regulation of midline axon repulsion.
Axon extension and guidance require a coordinated assembly of F-actin and microtubules as well as regulated translation. The molecular basis of how the translation of mRNAs encoding guidance proteins could be closely tied to the pace of cytoskeletal assembly is poorly understood. Previous studies have shown that the F-actin-microtubule crosslinker Short stop (Shot) is required for motor and sensory axon extension in the Drosophila embryo. Here, we provide biochemical and genetic evidence that Shot functions with a novel translation inhibitor, Krasavietz (Kra, Exba), to steer longitudinally directed CNS axons away from the midline. Kra binds directly to the C-terminus of Shot, and this interaction is required for the activity of Shot to support midline axon repulsion. shot and kra mutations lead to weak robo-like phenotypes, and synergistically affect midline avoidance of CNS axons. We also show that shot and kra dominantly enhance the frequency of midline crossovers in embryos heterozygous for slit or robo, and that in kra mutant embryos, some Robo-positive axons ectopically cross the midline that normally expresses the repellent Slit. Finally, we demonstrate that Kra also interacts with the translation initiation factor eIF2beta and inhibits translation in vitro. Together, these data suggest that Kra-mediated translational regulation plays important roles in midline axon repulsion and that Shot functions as a direct physical link between translational regulation and cytoskeleton reorganization.
Lee
Seongsoo
S
Department of Cell and Developmental Biology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
Nahm
Minyeop
M
Lee
Mihye
M
Kwon
Minjae
M
Kim
Euijae
E
Zadeh
Alireza Dehghani
AD
Cao
Hanwei
H
Kim
Hyung-Jun
HJ
Lee
Zang Hee
ZH
Oh
Seog Bae
SB
Yim
Jeongbin
J
Kolodziej
Peter A
PA
Lee
Seungbok
S
D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000502:physiology*; D002490:Central Nervous System / Q000196:embryology / Q000378:metabolism / Q000821:virology; D004330:Drosophila / Q000196:embryology* / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D040061:Eukaryotic Initiation Factor-5 / Q000235:genetics / Q000378:metabolism*; D039642:Eukaryotic Initiation Factors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008870:Microtubules; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D011971:Receptors, Immunologic / Q000378:metabolism; D000097905:Roundabout Proteins
D029721:Drosophila Proteins; D040061:Eukaryotic Initiation Factor-5; D039642:Eukaryotic Initiation Factors; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; C520428:Krasavietz protein, Drosophila; C450828:shot protein, Drosophila