scholarly journals Translation-dependent mRNA localization to Caenorhabditis elegans adherens junctions

Development ◽  
2021 ◽  
Author(s):  
Cristina Tocchini ◽  
Michèle Rohner ◽  
Laurent Guerard ◽  
Poulomi Ray ◽  
Stephen E. Von Stetina ◽  
...  

mRNA localization is an evolutionarily widespread phenomenon that can facilitate subcellular protein targeting. Extensive work has focused on mRNA targeting through “zip-codes” within untranslated regions (UTRs), while much less is known about translation-dependent cues. Here, we examine mRNA localization in Caenorhabditis elegans embryonic epithelia. From an smFISH-based survey, we identified mRNAs associated with the cell membrane or cortex, and with apical junctions in a stage- and cell type-specific manner. Mutational analyses for one of these transcripts, dlg-1/discs large, revealed that it relied on a translation-dependent process and did not require its 5’ or 3'UTRs. We suggest a model in which dlg-1 transcripts are co-translationally localized with the nascent protein: first the translating complex goes to the cell membrane using sequences located at the carboxy-terminus/3’ end, and then apically using amino-terminal/5’ sequences. These studies identify a translation-based process for mRNA localization within developing epithelia and determine the necessary cis-acting sequences for dlg-1 mRNA targeting.

2021 ◽  
Author(s):  
Cristina Tocchini ◽  
Michele Rohner ◽  
Stephen E. Von Stetina ◽  
Susan E. Mango

mRNA localization is an evolutionarily widespread phenomenon that facilitates sub-cellular protein targeting. Extensive work has focused on mRNA targeting through “zip codes” within untranslated regions (UTRs), while much less is known about translation-dependent cues. Here, we examine mRNA localization in Caenorhabditis elegans embryonic epithelia. From an smFISH-based survey, we identified mRNAs associated with the cell membrane or cortex, and with apical junctions in a stage- and cell type-specific manner. Mutational analyses for one of these transcripts, dlg-1/discs large, revealed that it relied on a translation-dependent process and did not require its 5′ or 3′ UTR. We suggest a model in which dlg-1 transcripts are co-translationally colocalized with the encoded protein: first the translating complex goes to the cell membrane through sequences of the SH3 domain, and then to the apical junction by the L27 and PDZ sequences. In addition, the Hook and GuK sequences contribute to the second step: they are required for mRNA, but not protein, to accumulate at the apical junctions from locations at or near the membrane. These studies identify a translation-based process for mRNA localization within developing epithelia and determine the necessary cis-acting sequences for dlg-1 mRNA targeting.


Author(s):  
Wai Hon Chooi ◽  
Quanbin Dong ◽  
Jeremy Zhi Yan Low ◽  
Clement Yuen ◽  
Jiah Shin Chin ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Christopher A. Brosnan ◽  
Alexander J. Palmer ◽  
Steven Zuryn

AbstractMulticellularity has coincided with the evolution of microRNAs (miRNAs), small regulatory RNAs that are integrated into cellular differentiation and homeostatic gene-regulatory networks. However, the regulatory mechanisms underpinning miRNA activity have remained largely obscured because of the precise, and thus difficult to access, cellular contexts under which they operate. To resolve these, we have generated a genome-wide map of active miRNAs in Caenorhabditis elegans by revealing cell-type-specific patterns of miRNAs loaded into Argonaute (AGO) silencing complexes. Epitope-labelled AGO proteins were selectively expressed and immunoprecipitated from three distinct tissue types and associated miRNAs sequenced. In addition to providing information on biological function, we define adaptable miRNA:AGO interactions with single-cell-type and AGO-specific resolution. We demonstrate spatial and temporal dynamicism, flexibility of miRNA loading, and suggest miRNA regulatory mechanisms via AGO selectivity in different tissues and during ageing. Additionally, we resolve widespread changes in AGO-regulated gene expression by analysing translatomes specifically in neurons.


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.


2008 ◽  
Vol 180 (5) ◽  
pp. 973-988 ◽  
Author(s):  
Andrew R. Jauregui ◽  
Ken C.Q. Nguyen ◽  
David H. Hall ◽  
Maureen M. Barr

Nephronophthisis (NPHP) is the most common genetic cause of end-stage renal disease in children and young adults. In Chlamydomonas reinhardtii, Caenorhabditis elegans, and mammals, the NPHP1 and NPHP4 gene products nephrocystin-1 and nephrocystin-4 localize to basal bodies or ciliary transition zones (TZs), but their function in this location remains unknown. We show here that loss of C. elegans NPHP-1 and NPHP-4 from TZs is tolerated in developing cilia but causes changes in localization of specific ciliary components and a broad range of subtle axonemal ultrastructural defects. In amphid channel cilia, nphp-4 mutations cause B tubule defects that further disrupt intraflagellar transport (IFT). We propose that NPHP-1 and NPHP-4 act globally at the TZ to regulate ciliary access of the IFT machinery, axonemal structural components, and signaling molecules, and that perturbing this balance results in cell type–specific phenotypes.


Development ◽  
2020 ◽  
Vol 147 (14) ◽  
pp. dev190330
Author(s):  
Brett R. Lancaster ◽  
James D. McGhee

ABSTRACTWe define a quantitative relationship between the affinity with which the intestine-specific GATA factor ELT-2 binds to cis-acting regulatory motifs and the resulting transcription of asp-1, a target gene representative of genes involved in Caenorhabditis elegans intestine differentiation. By establishing an experimental system that allows unknown parameters (e.g. the influence of chromatin) to effectively cancel out, we show that levels of asp-1 transcripts increase monotonically with increasing binding affinity of ELT-2 to variant promoter TGATAA sites. The shape of the response curve reveals that the product of the unbound ELT-2 concentration in vivo [i.e. (ELT-2free) or ELT-2 ‘activity’] and the largest ELT-XXTGATAAXX association constant (Kmax) lies between five and ten. We suggest that this (unitless) product [Kmax×(ELT-2free) or the equivalent product for any other transcription factor] provides an important quantitative descriptor of transcription-factor/regulatory-motif interaction in development, evolution and genetic disease. A more complicated model than simple binding affinity is necessary to explain the fact that ELT-2 appears to discriminate in vivo against equal-affinity binding sites that contain AGATAA instead of TGATAA.


2017 ◽  
Author(s):  
Rahul Chaudhari ◽  
Vishakha Dey ◽  
Aishwarya Narayan ◽  
Shobhona Sharma ◽  
Swati Patankar

The secretory pathway in Plasmodium falciparum has evolved to transport proteins to the host cell membrane and to an endosymbiotic organelle, the apicoplast. The latter can occur via the ER or the ER-Golgi route. Here, we study these three routes using proteins Erythrocyte Membrane Protein-1 (PfEMP1), Acyl Carrier Protein (ACP) and glutathione peroxidase-like thioredoxin peroxidase (PfTPxGl) and inhibitors of vesicular transport. As expected, the G protein dependent vesicular fusion inhibitor AlF4- and microtubule destabilizing drug vinblastine block the trafficking of PfEMP-1, a protein secreted to the host cell membrane. However, while both PfTPxGl and ACP are targeted to the apicoplast, only ACP trafficking remains unaffected by these treatments. This implies that G-protein dependent vesicles do not play a role in classical apicoplast protein targeting. Unlike the soluble protein ACP, we show that PfTPxGl is localized to the outermost membrane of the apicoplast. Thus, the parasite apicoplast acquires proteins via two different pathways: first, the vesicular trafficking pathway appears to handle not only secretory proteins, but an apicoplast membrane protein, PfTPxGl. Second, trafficking of apicoplast luminal proteins appear to be independent of G-protein coupled vesicles.


2017 ◽  
Author(s):  
Rahul Chaudhari ◽  
Vishakha Dey ◽  
Aishwarya Narayan ◽  
Shobhona Sharma ◽  
Swati Patankar

The secretory pathway in Plasmodium falciparum has evolved to transport proteins to the host cell membrane and to an endosymbiotic organelle, the apicoplast. The latter can occur via the ER or the ER-Golgi route. Here, we study these three routes using proteins Erythrocyte Membrane Protein-1 (PfEMP1), Acyl Carrier Protein (ACP) and glutathione peroxidase-like thioredoxin peroxidase (PfTPxGl) and inhibitors of vesicular transport. As expected, the G protein dependent vesicular fusion inhibitor AlF4- and microtubule destabilizing drug vinblastine block the trafficking of PfEMP-1, a protein secreted to the host cell membrane. However, while both PfTPxGl and ACP are targeted to the apicoplast, only ACP trafficking remains unaffected by these treatments. This implies that G-protein dependent vesicles do not play a role in classical apicoplast protein targeting. Unlike the soluble protein ACP, we show that PfTPxGl is localized to the outermost membrane of the apicoplast. Thus, the parasite apicoplast acquires proteins via two different pathways: first, the vesicular trafficking pathway appears to handle not only secretory proteins, but an apicoplast membrane protein, PfTPxGl. Second, trafficking of apicoplast luminal proteins appear to be independent of G-protein coupled vesicles.


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