Poly(A)-independent regulation of maternal hunchback translation in the Drosophila embryo

doi:10.1073/pnas.201284398

Poly(A)-independent regulation of maternal hunchback translation in the Drosophila embryo

Daniel Chagnovich* and
Ruth Lehmann†

Developmental Genetics Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, and Howard Hughes Medical Institute, New York, NY 10016

Edited by Judith Kimble, University of Wisconsin, Madison, WI, and approved July 17, 2001 (received for review June 7, 2001)

Abstract

Development of the Drosophila abdomen requires repression of maternal hunchback (hb) mRNA translation in the posterior of the embryo. This regulation involves at least four components: nanos response elements within the hb 3′ untranslated region and the activities of Pumilio (PUM), Nanos (NOS), and Brain tumor. To study this regulation, we have developed an RNA injection assay that faithfully recapitulates the regulation of the endogenous hb message. Previous studies have suggested that NOS and PUM can regulate translation by directing poly(A) removal. We have found that RNAs that lack a poly(A) tail and cannot be polyadenylated and RNAs that contain translational activating sequences in place of the poly(A) tail are still repressed in the posterior. These data demonstrate that the poly(A) tail is not required for regulation and suggest that NOS and PUM can regulate hb translation by two mechanisms: removal of the poly(A) tail and a poly(A)-independent pathway that directly affects translation.

Footnotes

↵ * Present address: Pfizer, Global Research and Development, Ann Arbor, MI 48105.
↵ † To whom reprint requests should be addressed at: Developmental Genetics Program, Skirball Institute/Howard Hughes Medical Institutes, 540 First Avenue, New York, NY 10016. E-mail: lehmann{at}saturn.med.nyu.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

UTR,

untranslated region;

PABP,

poly(A) binding protein;

hb,

hunchback;

nos, nanos,

pum, pumilio;

brat,

brain tumor;

F-Luc,

firefly luciferase;

R-Luc,

Renilla reniformis luciferase;

NRE,

nanos response element;

HFH,

hb 5′ UTR + F-Luc + hb 3′ UTR;

A/P,

ratio of anterior to posterior luciferase activity;

RT,

room temperature;

WT,

wild type;

F/R,

ratio of F-Luc/R-Luc;

HSL,

histone H1 3′ terminal stem loop;

HCH,

hb 5′ UTR + chloramphenicol acetyltransferase + hb 3′ UTR;

eIF,

eukaryotic initiation factor;

m7GpppG,

7-methyl guanosine