Two copies of a subelement from the Vg1 RNA localization sequence are sufficient to direct vegetal localization in Xenopus oocytes

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5013-5020 ◽  
Author(s):  
D. Gautreau ◽  
C.A. Cote ◽  
K.L. Mowry

Localization of mRNA has emerged as a fundamental mechanism for generating polarity during development. In vertebrates, one example of this phenomenon is Vg1 RNA, which is localized to the vegetal cortex of Xenopus oocytes. Vegetal localization of Vg1 RNA is directed by a 340-nt sequence element contained within its 3′ untranslated region. To investigate how such cis-acting elements function in the localization process, we have undertaken a detailed analysis of the precise sequence requirements for vegetal localization within the 340-nt localization element. We present evidence for considerable redundancy within the localization element and demonstrate that critical sequences lie at the ends of the element. Importantly, we show that a subelement from the 5′ end of the Vg1 localization element is, when duplicated, sufficient to direct vegetal localization. We suggest that the Vg1 localization element is composed of smaller, redundant sequence motifs and identify one such 6-nt motif as essential for localization. These results allow insight into what constitutes an RNA localization signal and how RNA sequence elements may act in the localization process.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ami Shah ◽  
Madison Ratkowski ◽  
Alessandro Rosa ◽  
Paul Feinstein ◽  
Thomas Bozza

AbstractOlfactory sensory neurons express a large family of odorant receptors (ORs) and a small family of trace amine-associated receptors (TAARs). While both families are subject to so-called singular expression (expression of one allele of one gene), the mechanisms underlying TAAR gene choice remain obscure. Here, we report the identification of two conserved sequence elements in the mouse TAAR cluster (T-elements) that are required for TAAR gene expression. We observed that cell-type-specific expression of a TAAR-derived transgene required either T-element. Moreover, deleting either element reduced or abolished expression of a subset of TAAR genes, while deleting both elements abolished olfactory expression of all TAARs in cis with the mutation. The T-elements exhibit several features of known OR enhancers but also contain highly conserved, unique sequence motifs. Our data demonstrate that TAAR gene expression requires two cooperative cis-acting enhancers and suggest that ORs and TAARs share similar mechanisms of singular expression.


Development ◽  
1999 ◽  
Vol 126 (4) ◽  
pp. 659-669 ◽  
Author(s):  
S.E. Bergsten ◽  
E.R. Gavis

Patterning of the anterior-posterior body axis during Drosophila development depends on the restriction of Nanos protein to the posterior of the early embryo. Synthesis of Nanos occurs only when maternally provided nanos RNA is localized to the posterior pole by a large, cis-acting signal in the nanos 3′ untranslated region (3′UTR); translation of unlocalized nanos RNA is repressed by a 90 nucleotide Translational Control Element (TCE), also in the 3′UTR. We now show quantitatively that the majority of nanos RNA in the embryo is not localized to the posterior pole but is distributed throughout the cytoplasm, indicating that translational repression is the primary mechanism for restricting production of Nanos protein to the posterior. Through an analysis of transgenes bearing multiple copies of nanos 3′UTR regulatory sequences, we provide evidence that localization of nanos RNA by components of the posteriorly localized germ plasm activates its translation by preventing interaction of nanos RNA with translational repressors. This mutually exclusive relationship between translational repression and RNA localization is mediated by a 180 nucleotide region of the nanos localization signal, containing the TCE. These studies suggest that the ability of RNA localization to direct wild-type body patterning also requires recognition of multiple, unique elements within the nanos localization signal by novel factors. Finally, we propose that differences in the efficiencies with which different RNAs are localized result from the use of temporally distinct localization pathways during oogenesis.


Development ◽  
1999 ◽  
Vol 126 (22) ◽  
pp. 4943-4953 ◽  
Author(s):  
A.P. Chan ◽  
M. Kloc ◽  
L.D. Etkin

Vegetally localized transcripts have been implicated in a number of important biological functions, including cell fate determination and embryonic patterning. We have isolated a cDNA, fatvg, which encodes a localized maternal transcript that exhibits a localization pattern reminiscent of Vg1 mRNA. fatvg is the homologue of a mammalian gene expressed in adipose tissues. The fatvg transcript, unlike Vg1 which localizes strictly through the Late pathway, also associates with the mitochondrial cloud that is characteristic of the METRO or Early pathway. This suggests that fatvg mRNA may utilize both the METRO and Late pathways to localize to the vegetal cortex during oogenesis. We have dissected the cis-acting localization elements of fatvg mRNA and compared these elements with Vg1 mRNA. Our results indicate that, like most localized RNAs, in a variety of systems, transcripts of fatvg contain localization elements in the 3′UTR. The 3′UTR of fatvg mRNA contains multiple elements that are able to function independently; however, it functions most efficiently when all of the elements are present. We have defined a short 25-nucleotide element that can direct vegetal localization as a single copy. This element differs in sequence from previously described Vg1 localization elements, suggesting that different localization elements are involved in the localization of RNAs through the Late pathway.


Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2791-2800 ◽  
Author(s):  
E.R. Gavis ◽  
L. Lunsford ◽  
S.E. Bergsten ◽  
R. Lehmann

Correct formation of the Drosophila body plan requires restriction of nanos activity to the posterior of the embryo. Spatial regulation of nanos is achieved by a combination of RNA localization and localization-dependent translation such that only posteriorly localized nanos RNA is translated. Cis-acting sequences that mediate both RNA localization and translational regulation lie within the nanos 3′ untranslated region. We have identified a discrete translational control element within the nanos 3′ untranslated region that acts independently of the localization signal to mediate translational repression of unlocalized nanos RNA. Both the translational regulatory function of the nanos 3′UTR and the sequence of the translational control element are conserved between D. melanogaster and D. virilis. Furthermore, we show that the RNA helicase Vasa, which is required for nanos RNA localization, also plays a critical role in promoting nanos translation. Our results specifically exclude models for translational regulation of nanos that rely on changes in polyadenylation.


2003 ◽  
Vol 71 (6) ◽  
pp. 311-321 ◽  
Author(s):  
Luetta Allen ◽  
Malgorzata Kloc ◽  
Laurence D. Etkin

2004 ◽  
Vol 32 (5) ◽  
pp. 702-704 ◽  
Author(s):  
H. Chabanon ◽  
D. Nury ◽  
I. Mickleburgh ◽  
B. Burtle ◽  
J. Hesketh

Subcellular localization of mRNAs is a key mechanism for the synthesis of proteins close to their site of function. The mRNA encoding MT-1 (metallothionein-1) is localized in the perinuclear cytoplasm, where it is associated with cytoskeletal-bound polysomes. This localization relies on sequences present in the 3′-UTR (3′-untranslated region). The present study aims to characterize the cis-acting localization element(s) within the 3′-UTR. Using transfected cells expressing tagged MT-1 differing in their 3′-UTRs (deleted or mutated), the section(s) of this region required for directing MT-1 transcripts to the perinuclear cytoplasm has been investigated. Different 3′-UTRs were also used in UV cross-linking experiments that highlighted two distinct regions (nt 26–30 and 66–76) necessary for the binding of a protein of approx. 50 kDa, presumably involved in the mRNA targeting. The poor sequence homology between the MT-1 3′-UTR of various species, together with the bipartite nature of the required cis-element, indicates the involvement of a particular structure in the localization signal. The secondary structure of the MT-1 3′-UTR was investigated using enzymic and chemical probing. Current structural analysis of mutant 3′-UTRs will allow the critical structural features of the MT-1 mRNA perinuclear localization signal to be defined.


Development ◽  
2001 ◽  
Vol 128 (3) ◽  
pp. 427-435 ◽  
Author(s):  
S. Evans Bergsten ◽  
T. Huang ◽  
S. Chatterjee ◽  
E.R. Gavis

Localization of nanos (nos) mRNA to the germ plasm at the posterior pole of the Drosophila embryo is essential to activate nos translation and thereby generate abdominal segments. nos RNA localization is mediated by a large cis-acting localization signal composed of multiple, partially redundant elements within the nos 3′ untranslated region. We identify a protein of approximately 75 kDa (p75) that interacts specifically with the nos +2′ localization signal element. We show that the function of this element can be delimited to a 41 nucleotide domain that is conserved between D. melanogaster and D. virilis, and confers near wild-type localization when present in three copies. Two small mutations within this domain eliminate both +2′ element localization function and p75 binding, consistent with a role for p75 in nos RNA localization. In the intact localization signal, the +2′ element collaborates with adjacent localization elements. We show that different +2′ element mutations not only abolish collaboration between the +2′ and adjacent +1 element but also produce long-range deleterious effects on localization signal function. Our results suggest that higher order structural interactions within the localization signal, which requires factors such as p75, are necessary for association of nos mRNA with the germ plasm.


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