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Chiara Gamberi

Publications and source records attributed to Chiara Gamberi.

5 recordsLinked to original sources
PubMed2006

Cap-dependent translational inhibition establishes two opposing morphogen gradients in Drosophila embryos.

In the early Drosophila embryo, asymmetric distribution of transcription factors, established as a consequence of translational control of their maternally derived mRNAs, initiates pattern formation . For instance, translation of the uniformly distributed maternal hunchback (hb) mRNA is inhibited at the posterior to form an anterior-to-posterior protein concentration gradient along the longitudinal axis . Inhibition of hb mRNA translation requires an mRNP complex (the NRE complex), which consists of Nanos (Nos), Pumilio (Pum), and Brain tumor (Brat) proteins, and the Nos responsive element (NRE) present in the 3' UTR of hb mRNA . The identity of the mRNA 5' effector protein that is responsible for this translational inhibition remained elusive. Here we show that d4EHP, a cap binding protein that represses caudal (cad) mRNA translation , also inhibits hb mRNA translation by interacting simultaneously with the mRNA 5' cap structure (m(7)GpppN, where N is any nucleotide) and Brat. Thus, by regulating Cad and Hb expression, d4EHP plays a key role in establishing anterior-posterior axis polarity in the Drosophila embryo.

Animals↗
PubMed2006

Drosophila RNA binding proteins.

RNA binding proteins are fundamental mediators of gene expression. The use of the model organism Drosophila has helped to elucidate both tissue-specific and ubiquitous functions of RNA binding proteins. These proteins mediate all aspects of the mRNA lifespan including splicing, nucleocytoplasmic transport, localization, stability, translation, and degradation. Most RNA binding proteins fall into several major groups, based on their RNA binding domains. As well, experimental data have revealed several proteins that can bind RNA but lack canonical RNA binding motifs, suggesting the presence of as yet uncharacterized RNA binding domains. Here, we present the major classes of Drosophila RNA binding proteins with special focus on those with functional information.

Amino Acid Sequence↗
PubMed2003

The C elegans hunchback homolog, hbl-1, controls temporal patterning and is a probable microRNA target.

hunchback regulates the temporal identity of neuroblasts in Drosophila. Here we show that hbl-1, the C. elegans hunchback ortholog, also controls temporal patterning. Furthermore, hbl-1 is a probable target of microRNA regulation through its 3'UTR. hbl-1 loss-of-function causes the precocious expression of adult seam cell fates. This phenotype is similar to loss-of-function of lin-41, a known target of the let-7 microRNA. Like lin-41 mutations, hbl-1 loss-of-function partially suppresses a let-7 mutation. The hbl-1 3'UTR is both necessary and sufficient to downregulate a reporter gene during development, and the let-7 and lin-4 microRNAs are both required for HBL-1/GFP downregulation. Multiple elements in the hbl-1 3'UTR show complementarity to regulatory microRNAs, suggesting that microRNAs directly control hbl-1. MicroRNAs may likewise function to regulate Drosophila hunchback during temporal patterning of the nervous system.

3' Untranslated Regions↗
PubMed2002

An anterior function for the Drosophila posterior determinant Pumilio.

Bicoid is a key determinant of anterior Drosophila development. We demonstrate that the prototypical Puf protein Pumilio temporally regulates bicoid (bcd) mRNA translation via evolutionarily conserved Nanos response elements (NRE) in its 3'UTR. Disruption of Pumilio-bcd mRNA interaction by either Pumilio or bcd NRE mutations caused delayed bcd mRNA deadenylation and stabilization, resulting in protracted Bicoid protein expression during embryogenesis. Phenotypically, embryos from transgenic mothers that harbor bcd NRE mutations exhibited dominant anterior patterning defects and we discovered similar head defects in embryos from pum(-) mothers. Hence, Pumilio is required for normal anterior development. Since bcd mRNA resides outside the posterior gradient of the canonical partner of Pumilio, Nanos, our data suggest that Pumilio can recruit different partners to specifically regulate distinct mRNAs.

3' Untranslated Regions↗