LARP1 functions as a molecular switch for mTORC1-mediated translation of an essential class of mRNAs

Hong, Sangjin; Freeberg, Mallory; Han, Ting; Kamath, Avani; Yao, Yao; Fukuda, Tomoko; Suzuki, Takahiro; Kim, John K.; Inoki, Ken

doi:10.7554/elife.25237

Cited by 163 publications

(254 citation statements)

References 36 publications

Supporting

Mentioning

236

Contrasting

Order By: Relevance

“…The human LARP1 phosphosites are not conserved with those we found in Chlamydomonas. However, based on the NCBI conserved domain searching (Marchler‐Bauer & Bryant, ), the DM15 domain required for the interaction of LARP1 with mTORC1 in human cell lines is conserved in Chlamydomonas LARP1, and the phospho‐Ser817 detected in our study is adjacent to the DM15 domain (877‐915) in Chlamydomonas, a region in mammalian LARP1shown to be required for interaction with mTORC1 (Hong et al ., ).…”

Section: Discussionmentioning

confidence: 97%

“…In mammals, LARP1 phosphorylation also requires mTORC1 (Hsu et al, 2011;Yu et al, 2011;Kang et al, 2013) with studies in human cell lines establishing LARP1 as a target of mTORC1 and S6K with nonphosphorylated LARP1 interacting with both 5 0 and 3 0 UTRs of RP mRNAs and inhibiting their translation (Hong et al, 2017). Additional reports have shown LARP1 as a direct substrate of mTORC1 in mammalian cells with mTORC1 controlling Terminal Oligopyrimidine (TOP) mRNA translation via LARP1 (Fonseca et al, 2015;Hong et al, 2017). The dramatic modulation of LARP1 phosphorylation detected in our study indicates that LARP1 may have a parallel role in Chlamydomonas.…”

Section: Sites Modulated By Torc1 Inhibitionknown Tor Pathway Associamentioning

confidence: 99%

See 1 more Smart Citation

Investigating the effect of target of rapamycin kinase inhibition on the Chlamydomonas reinhardtii phosphoproteome: from known homologs to new targets

et al. 2018

View full text Add to dashboard Cite

Target of rapamycin (TOR) kinase is a conserved regulator of cell growth whose activity is modulated in response to nutrients, energy and stress. Key proteins involved in the pathway are conserved in the model photosynthetic microalga Chlamydomonas reinhardtii, but the substrates of TOR kinase and downstream signaling network have not been elucidated. Our study provides a new resource for investigating the phosphorylation networks governed by the TOR kinase pathway in Chlamydomonas. We used quantitative phosphoproteomics to investigate the effects of inhibiting Chlamydomonas TOR kinase on dynamic protein phosphorylation. Wild-type and AZD-insensitive Chlamydomonas strains were treated with TOR-specific chemical inhibitors (rapamycin, AZD8055 and Torin1), after which differentially affected phosphosites were identified. Our quantitative phosphoproteomic dataset comprised 2547 unique phosphosites from 1432 different proteins. Inhibition of TOR kinase caused significant quantitative changes in phosphorylation at 258 phosphosites, from 219 unique phosphopeptides. Our results include Chlamydomonas homologs of TOR signaling-related proteins, including a site on RPS6 with a decrease in phosphorylation. Additionally, phosphosites on proteins involved in translation and carotenoid biosynthesis were identified. Follow-up experiments guided by these phosphoproteomic findings in lycopene beta/epsilon cyclase showed that carotenoid levels are affected by TORC1 inhibition and carotenoid production is under TOR control in algae.

show abstract

Section: Discussionmentioning

confidence: 97%

Section: Sites Modulated By Torc1 Inhibitionknown Tor Pathway Associamentioning

confidence: 99%

Investigating the effect of target of rapamycin kinase inhibition on the Chlamydomonas reinhardtii phosphoproteome: from known homologs to new targets

et al. 2018

View full text Add to dashboard Cite

show abstract

“…PABPC1 (polyadenylate-binding protein cytoplasmic 1); PTB (polypyrimidine tract-binding protein 1); CPEB1 (cytoplasmic polyadenylation element-binding protein 1); LARP1 (La-related protein 1); PKR (double-stranded RNA-activated protein kinase); FMR1 (Fragile X mental retardation protein 1). Domains: RRM (RNA recognition motif ); MLLE (Met-Leu-Leu-Glu motif ); NES (nuclear export sequence); NLS (nuclear localization sequence); ZZ (ZZ-type zinc finger domain); LAM (La motif ); RRM-L5 (RRM-like motif 5); DSRM (double-stranded RNA-binding motif ); STK (Ser-Thr kinase domain); KH (K homology RNA-binding domain) (Hong et al, 2017). These data suggest that LARP1 acts as a phosphorylation sensitive molecular switch activating or repressing cell proliferation in response to environmental cues (Hong et al, 2017).…”

Section: La-related Proteinmentioning

confidence: 99%

Trans‐acting translational regulatory RNA binding proteins

et al. 2018

View full text Add to dashboard Cite

The canonical molecular machinery required for global mRNA translation and its control has been well defined, with distinct sets of proteins involved in the processes of translation initiation, elongation and termination. Additionally, noncanonical, trans‐acting regulatory RNA‐binding proteins (RBPs) are necessary to provide mRNA‐specific translation, and these interact with 5′ and 3′ untranslated regions and coding regions of mRNA to regulate ribosome recruitment and transit. Recently it has also been demonstrated that trans‐acting ribosomal proteins direct the translation of specific mRNAs. Importantly, it has been shown that subsets of RBPs often work in concert, forming distinct regulatory complexes upon different cellular perturbation, creating an RBP combinatorial code, which through the translation of specific subsets of mRNAs, dictate cell fate. With the development of new methodologies, a plethora of novel RNA binding proteins have recently been identified, although the function of many of these proteins within mRNA translation is unknown. In this review we will discuss these methodologies and their shortcomings when applied to the study of translation, which need to be addressed to enable a better understanding of trans‐acting translational regulatory proteins. Moreover, we discuss the protein domains that are responsible for RNA binding as well as the RNA motifs to which they bind, and the role of trans‐acting ribosomal proteins in directing the translation of specific mRNAs.This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA–Protein ComplexesTranslation > Translation RegulationTranslation > Translation Mechanisms

show abstract

“…Crucially, the prototypical LARP family member, LARP1, has been previously shown to directly interact with RP-mRNAs through their 5' Terminal Oligo-Pyrimidine (5' TOP) motif, a characteristic stretch of 6-12 pyrimidines at the 5′ end of many mRNAs which code for proteins involved in the translation machinery (Fonseca et al, 2015;Lahr et al, 2017;Tcherkezian et al, 2014). This interaction is known to be 160 regulated by the mammalian Target of Rapamycin Complex-1 (mTORC1), ultimately acting to control RP-mRNAs translation and ribosome biogenesis downstream of the mTORC1 pathway (Hong et al, 2017). We therefore assessed whether LARP1 was important for RP-mRNAs localization to protrusions, using an RNA-FISH probe against RPL34 mRNA, which is one of the most enriched RP-mRNAs in protrusions of MDA-MB231 cells ( Figure 1D).…”

Section: Depletion Of Larp Proteins Reveals a Role For Larp6 In Rp-mrmentioning

confidence: 99%

“…LARP1 binds to the 5'cap, 5'TOP, as well as the Poly-A tail of RP-mRNAs (Al-Ashtal et al, 2019), and is thought to be directly phosphorylated on several residues upon activation of mTORC1 (Fonseca et al, 2018). A recent model proposes that these phosphorylation 780 events act as a molecular switch, converting LARP1 from a translational inhibitor to activator, thus upregulating the translation of RP-mRNAs and subsequent ribosome biogenesis (Hong et al, 2017). Our findings here reveal an independent molecular mechanism for translational regulation of RP-mRNAs in synergy with mesenchymal-like cell migration.…”

mentioning

confidence: 99%

Subcellular mRNA localization regulates ribosome biogenesis in migrating cells

Dermit

Dodel

Lee

et al. 2019

Preprint

View full text Add to dashboard Cite

Translation of Ribosomal Protein coding mRNAs (RP-mRNAs) constitutes a key step in regulation of ribosome biogenesis, but the mechanisms which modulate RP-mRNAs 20 translation under various cellular and environmental conditions are poorly understood. Here we show that the subcellular localization of RP-mRNAs acts as a key regulator of their translation in migrating cells. As cells migrate into their surroundings, RP-mRNAs localize to the actin-rich protrusions at the front the cells. This localization is mediated by La related protein-6 (LARP6), an RNA Binding Protein that is enriched in protrusions. Protrusions act as 25 hotspots of translation for localized RP-mRNAs, resulting in enhancement of RP synthesis, upregulation of ribosome biogenesis, and increased overall protein synthesis of migrating cells in a LARP6 dependent manner. In human breast carcinomas, Epithelial to Mesenchymal Transition (EMT) upregulates LARP6 expression to enhance protein synthesis, and can be targeted using a small molecule inhibitor that interferes with LARP6 RNA binding. Our findings 30 reveal LARP6 mediated mRNA localization as a key regulator of ribosome biogenesis during cell-migration, and demonstrate a role for this process in cancer progression downstream of EMT.35 65 mRNAs to promote their enrichment in protrusions. Protrusions are also highly enriched in translation initiation and elongation factors, acting as hotspots for translation of localized RP-mRNAs. LARP6 dependent localization of RP-mRNAs results in upregulation of RP levels, leading to enhancement of ribosome biogenesis and global protein synthesis in migrating cells. In human breast carcinomas, higher LARP6 protein expression is associated with the 70 invasive mesenchymal-like subtypes. EMT induces LARP6 protein expression, which acts to promote malignant growth and invasion. Crucially, LARP6 regulation of RP-mRNAs can be therapeutically targeted using small molecule inhibitors which specifically interfere with its RNA binding. Collectively, our findings reveal a new mechanism that governs ribosome biogenesis in mesenchymal-like migratory cells via subcellular localization of RP-mRNAs, and 75 demonstrate a therapeutically targetable role for this process in cancer downstream of EMT. Results 80 RP-mRNAs localize to protrusions of all migratory cellsWe utilized a micro-porous transwell filter based method (Mardakheh et al., 2015;Mili et al., 2008) to assess if RP-mRNAs localization to actin-rich protrusions was a conserved feature of all migratory cells. We modified the procedure to allow cells to adhere to the top of the filter first, followed by synchronized induction of protrusion formation through the pores (Figure 85 1A). Importantly, the small (3µm) size of the pores enables protrusions to form but prevents the cell bodies from passing through, thus resulting in separation of the protrusions and the cell bodies on opposite sides of the filter, which can be independently imaged or purified for multi-omics analysis ( Figure 1A). Using this method, we profiled ...

show abstract

LARP1 functions as a molecular switch for mTORC1-mediated translation of an essential class of mRNAs

Cited by 163 publications

References 36 publications

Investigating the effect of target of rapamycin kinase inhibition on the Chlamydomonas reinhardtii phosphoproteome: from known homologs to new targets

Investigating the effect of target of rapamycin kinase inhibition on the Chlamydomonas reinhardtii phosphoproteome: from known homologs to new targets

Trans‐acting translational regulatory RNA binding proteins

Subcellular mRNA localization regulates ribosome biogenesis in migrating cells

Contact Info

Product

Resources

About