Affinage

LAS1L

Ribosomal biogenesis protein LAS1L · UniProt Q9Y4W2

Round 2 corrected
Length
734 aa
Mass
83.1 kDa
Annotated
2026-04-28
45 papers in source corpus 11 papers cited in narrative 11 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

LAS1L is a nucleolar HEPN-domain endoribonuclease essential for 60S ribosomal subunit maturation, functioning as the endonuclease that cleaves 27SB pre-rRNA at site C2 within ITS2 (PMID:26638174). It assembles with the polynucleotide kinase NOL9/Grc3 into a tetrameric complex in which the two enzymes reciprocally activate each other: LAS1L cleavage generates a 5'-OH substrate that NOL9/Grc3 phosphorylates to enable Rat1-Rai1 exonucleolytic trimming, thereby coordinately removing ITS2 (PMID:26638174, PMID:28652339). In mammalian cells, LAS1L further associates with the Rix1-like complex (PELP1, TEX10, WDR18) and the SUMO protease SENP3, whose nucleolar localization depends on active RNA Pol I transcription, and its activity is post-translationally regulated by USP36-mediated deubiquitination and SUMOylation at K565, both required for ITS2 processing (PMID:22190735, PMID:39356143). Loss of LAS1L blocks 28S rRNA synthesis, triggers nucleolar stress, and activates p53-dependent G1 arrest (PMID:20647540).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2010 High

    Establishing that LAS1L is required for ribosome biogenesis resolved the cellular role of this uncharacterized nucleolar protein, showing that its depletion blocks 28S rRNA maturation and triggers p53-dependent growth arrest.

    Evidence siRNA knockdown in human cells with Northern blot rRNA processing analysis and flow cytometry

    PMID:20647540

    Open questions at the time
    • Enzymatic activity unknown
    • Direct rRNA substrate not identified
    • Mechanism of rRNA processing block undefined
  2. 2011 High

    Identification of the LAS1L-PELP1-TEX10-WDR18-NOL9-SENP3 nucleolar complex and its co-fractionation with pre-60S subunits established the multiprotein context in which LAS1L functions and linked its localization to active RNA Pol I transcription and SENP3-dependent SUMOylation.

    Evidence Reciprocal co-immunoprecipitation, sucrose gradient fractionation, siRNA knockdown, and RNA Pol I inhibition in human cells; cross-species genetic analysis in yeast and human cells

    PMID:22083961 PMID:22190735

    Open questions at the time
    • Whether LAS1L is the direct endonuclease or an accessory factor was unknown
    • Stoichiometry of the complex undefined
    • Role of individual subunits in catalysis unresolved
  3. 2012 High

    Demonstration that Grc3/NOL9 is the principal Las1-interacting partner and that its kinase activity is required for pre-rRNA processing established the functional coupling between Las1 and Grc3 within the pre-60S particle.

    Evidence Co-immunoprecipitation, yeast genetic depletion, in vivo kinase assays, Northern blot

    PMID:23175604

    Open questions at the time
    • Las1 catalytic activity not yet demonstrated biochemically
    • Nature of the Las1-Grc3 crosstalk unresolved
  4. 2015 High

    In vitro reconstitution proved Las1 is the long-sought C2 endonuclease, generating a 2',3'-cyclic phosphate and a 5'-OH that Grc3 phosphorylates to enable Rat1-Rai1 exonuclease activity — resolving how ITS2 removal is coordinately executed by a four-subunit Las1 complex.

    Evidence In vitro endonuclease reconstitution with purified components, mutational analysis, RNA substrate assays

    PMID:26638174

    Open questions at the time
    • Structural basis of C2 site specificity unknown
    • How Grc3 directs Las1 to C2 unresolved
    • HEPN domain contribution not yet dissected
  5. 2017 High

    Reciprocal activation between Las1 and Grc3 was demonstrated — Grc3 programs Las1 for site-specific C2 cleavage while Las1 activates Grc3 kinase toward RNA — revealing the bidirectional allosteric mechanism governing coordinated ITS2 processing.

    Evidence In vitro endonuclease/kinase assays, yeast genetics, biochemical reconstitution of tetrameric complex

    PMID:28652339

    Open questions at the time
    • Structural basis of allosteric communication unknown
    • Whether conformational states regulate activity in vivo untested
  6. 2018 High

    Characterization of Grc3 substrate specificity (RNA over DNA) and identification of active-site residues required for Las1-coupled cleavage refined the kinase mechanism and confirmed that cleavage–phosphorylation coupling is direct.

    Evidence In vitro kinase assays with RNA/DNA substrates, site-directed mutagenesis, yeast complementation

    PMID:29440475

    Open questions at the time
    • Kinetic parameters of coupled reaction not determined
    • Whether additional cofactors modulate kinase selectivity unknown
  7. 2020 High

    Systematic mutagenesis of the Las1 HEPN domain defined the composite active site formed by two HEPN motifs, established that conformational flexibility between HEPN domains is required for cleavage fidelity, and confirmed Las1 as a bona fide HEPN endoribonuclease.

    Evidence In vitro nuclease assays, HEPN-HEPN' chimera reconstitution, extensive site-directed mutagenesis, yeast complementation

    PMID:32220933

    Open questions at the time
    • No high-resolution structure of Las1 HEPN domain available
    • Mechanism of cleavage site selection at nucleotide resolution unresolved
  8. 2022 Medium

    Discovery that hnRNPA1 regulates LAS1L alternative splicing by binding intronic sequences to modulate the ratio of long and short isoforms revealed a layer of pre-mRNA-level regulation with phenotypic consequences for cell migration.

    Evidence RIP assay, RNA pull-down, splicing assays, Transwell migration/invasion in lung cancer cells

    PMID:35814393

    Open questions at the time
    • Functional difference between LAS1L-L and LAS1L-S isoforms in ribosome biogenesis not defined
    • Relevance beyond lung cancer cells untested
    • Single-lab finding
  9. 2023 Medium

    Covalent targeting of LAS1L at C264 by HEN-463 disrupted the LAS1L–NOL9 interaction, caused cytoplasmic translocation, and blocked 28S rRNA maturation, activating the NPM1-MDM2-p53 axis — demonstrating LAS1L druggability and linking ribosome biogenesis disruption to p53 activation in AML cells.

    Evidence Chemical biology (covalent inhibitor), co-immunoprecipitation, subcellular fractionation, rRNA processing analysis in NPM1-mutant AML cells

    PMID:36796466

    Open questions at the time
    • Selectivity of HEN-463 across the proteome not fully profiled
    • In vivo efficacy untested
    • Single-lab study
  10. 2024 High

    USP36 was shown to deubiquitinate and stabilize LAS1L and NOL9, and to mediate SUMOylation of LAS1L at K565; the K565R mutation failed to rescue ITS2 processing, establishing that SUMOylation is functionally required for LAS1L endonuclease activity in cells.

    Evidence Co-immunoprecipitation, deubiquitination/SUMOylation assays, K565R mutagenesis rescue, Northern blot rRNA processing

    PMID:39356143

    Open questions at the time
    • How SUMOylation at K565 modulates LAS1L activity mechanistically is unknown
    • Whether additional SUMOylation sites contribute is untested
    • Structural impact of SUMO conjugation unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • No high-resolution structure of the human LAS1L–NOL9 complex exists, the mechanism by which HEPN domain conformational dynamics achieve C2 site selectivity is unresolved, and the functional distinction between LAS1L splice isoforms in ribosome biogenesis remains undefined.
  • No cryo-EM or crystal structure of human Las1 complex
  • Nucleotide-level basis of C2 recognition unknown
  • In vivo roles of LAS1L-L versus LAS1L-S isoforms undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 3 GO:0140098 catalytic activity, acting on RNA 3
Localization
GO:0005634 nucleus 2 GO:0005730 nucleolus 2
Pathway
R-HSA-8953854 Metabolism of RNA 6 GO:0140098 catalytic activity, acting on RNA 3
Partners
HNRNPA1NOL9PELP1SENP3TEX10USP36WDR18
Complex memberships
Las1 complex (Las1-Grc3-Rat1-Rai1)Rix1-like complex (PELP1-TEX10-WDR18-LAS1L-NOL9-SENP3)

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2010 LAS1L is a nucleolar protein required for cell proliferation and ribosome biogenesis; depletion of LAS1L inhibits rRNA processing, blocks synthesis of mature 28S rRNA, and causes p53-dependent G1 arrest. siRNA knockdown in human cells, rRNA processing analysis (Northern blot), cell cycle analysis by flow cytometry Molecular and cellular biology High 20647540
2011 LAS1L forms a novel nucleolar complex with PELP1, TEX10, WDR18 (mammalian Rix1 complex homologues), NOL9, and SENP3 that co-fractionates with the 60S preribosomal subunit; depletion of complex members causes p53-dependent G1 arrest and defects in ITS2 pre-rRNA processing; nucleolar localization of this complex requires active RNA Pol I transcription and the SUMO protease SENP3. Co-immunoprecipitation, sucrose gradient fractionation, siRNA knockdown, rRNA processing analysis, RNA Pol I inhibition, SENP3 depletion Molecular biology of the cell High 22190735
2011 In both budding yeast and human cells, Las1/LAS1L is required for ITS2 processing: in yeast it is needed for Rrp6-dependent formation of the 5.8S rRNA 3' end and for Rat1-dependent formation of the 25S rRNA 5' end, indicating coordinated pre-rRNA processing at both ends of ITS2. Genetic depletion/mutant analysis in S. cerevisiae and human cells, Northern blot rRNA processing analysis Molecular and cellular biology High 22083961
2012 Yeast Las1 functions in ribosome biogenesis by associating with 27S rRNA and the Nsa1/Rix1-containing pre-60S particle; Grc3 is a major Las1-interacting protein, and the kinase activity of Grc3 is required for efficient pre-rRNA processing — depletion of either Las1 or Grc3 causes accumulation of 27S and 7S rRNA intermediates and impairs 60S subunit synthesis. Co-immunoprecipitation, sucrose gradient fractionation, yeast genetic depletion, in vivo kinase assay, Northern blot Nucleic acids research High 23175604
2015 Las1 is the long-sought endonuclease that cleaves 27SB pre-rRNA at site C2, generating a 5'-OH end at 26S pre-rRNA and a 2',3'-cyclic phosphate at the 3' end of 7S pre-rRNA; it assembles with Grc3, Rat1, and Rai1 into a four-subunit RNA processome (Las1 complex) where Grc3 subsequently phosphorylates the 5'-OH of 26S pre-rRNA enabling Rat1-Rai1 exonuclease to generate 25S' pre-rRNA, thus coordinately removing ITS2. In vitro reconstitution of endonuclease activity, biochemical fractionation, mutational analysis, RNA substrate assays Molecular cell High 26638174
2017 The Grc3 polynucleotide kinase programs Las1 endoribonuclease for specific C2 cleavage: Grc3 drives Las1 nuclease activity to the targeted C2 site both in vitro and in vivo; Las1 reciprocally activates Grc3 kinase activity exclusively toward single-stranded RNA; together they form a tetrameric complex required for competent rRNA processing, with parallels to the RNaseL/Ire1 RNA splicing family. In vitro endonuclease and kinase assays, yeast genetics, co-immunoprecipitation, biochemical reconstitution of tetrameric complex Proceedings of the National Academy of Sciences of the United States of America High 28652339
2018 Grc3 has distinct substrate preference for RNA (over DNA) as a polynucleotide kinase; specific conserved residues at the Grc3 kinase active site are required for Grc3-directed Las1-mediated pre-rRNA cleavage both in vitro and in vivo; the Grc3–Las1 crosstalk directly couples cleavage and phosphorylation during pre-rRNA processing. In vitro kinase assays with RNA/DNA substrates, site-directed mutagenesis of kinase active site, in vivo yeast complementation assays RNA (New York, N.Y.) High 29440475
2020 Las1 is a HEPN domain-containing endoribonuclease; both HEPN nuclease motifs (forming a composite active site) are required for Las1 nuclease activity and fidelity; conformational flexibility of the two HEPN domains is important for proper RNA cleavage; systematic mutagenesis defined the consensus Las1 HEPN motif with canonical and specialized elements. In vitro nuclease assays, in vivo S. cerevisiae complementation, systematic site-directed mutagenesis, Las1 HEPN-HEPN' chimera reconstitution, sequence analysis The Journal of biological chemistry High 32220933
2023 Covalent binding of the compound HEN-463 to C264 of LAS1 disrupts the LAS1–NOL9 interaction, causing LAS1 translocation to the cytoplasm and inhibiting 28S rRNA maturation; this activates the NPM1-MDM2-p53 pathway leading to p53 stabilization in NPM1-mutant AML cells. Chemical biology (covalent inhibitor), co-immunoprecipitation, subcellular fractionation, rRNA processing analysis, cell viability and apoptosis assays Pharmacological research Medium 36796466
2024 USP36 interacts with both LAS1L and NOL9, stabilizes them via deubiquitination, and mediates SUMOylation of LAS1L predominantly at lysine K565; the K565R SUMOylation-deficient mutant cannot rescue ITS2 processing defects caused by endogenous LAS1L knockdown, demonstrating that USP36-mediated LAS1L SUMOylation is required for ITS2 pre-rRNA processing. Co-immunoprecipitation, deubiquitination assays, SUMOylation assays, site-directed mutagenesis (K565R), siRNA rescue experiments, Northern blot rRNA processing analysis Cancer research communications High 39356143
2022 hnRNPA1 directly binds to LAS1L pre-mRNA at two intronic sites (UAGGGU and UGGGGU in intron 9) to inhibit splicing of LAS1L exon 9; the ratio of long (LAS1L-L) to short (LAS1L-S) isoforms regulated by hnRNPA1 promotes migration, invasion, and EMT in lung cancer cells. RIP assay, RNA pull-down assay, AGE splicing assay, Transwell migration/invasion assays, siRNA knockdown Frontiers in oncology Medium 35814393

Source papers

Stage 0 corpus · 45 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 Insights into RNA biology from an atlas of mammalian mRNA-binding proteins. Cell 1718 22658674
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2006 A probability-based approach for high-throughput protein phosphorylation analysis and site localization. Nature biotechnology 1336 16964243
2011 Systematic and quantitative assessment of the ubiquitin-modified proteome. Molecular cell 1334 21906983
2015 A human interactome in three quantitative dimensions organized by stoichiometries and abundances. Cell 1015 26496610
2012 The mRNA-bound proteome and its global occupancy profile on protein-coding transcripts. Molecular cell 973 22681889
2005 Nucleolar proteome dynamics. Nature 934 15635413
2005 The DNA sequence of the human X chromosome. Nature 816 15772651
2003 Complete sequencing and characterization of 21,243 full-length human cDNAs. Nature genetics 754 14702039
2011 A proteome-wide, quantitative survey of in vivo ubiquitylation sites reveals widespread regulatory roles. Molecular & cellular proteomics : MCP 749 21890473
2007 Large-scale mapping of human protein-protein interactions by mass spectrometry. Molecular systems biology 733 17353931
2021 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. Cell 705 33961781
2012 A census of human soluble protein complexes. Cell 689 22939629
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2018 High-Density Proximity Mapping Reveals the Subcellular Organization of mRNA-Associated Granules and Bodies. Molecular cell 580 29395067
2017 Anticancer sulfonamides target splicing by inducing RBM39 degradation via recruitment to DCAF15. Science (New York, N.Y.) 533 28302793
1994 Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides. Gene 492 8125298
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
2022 OpenCell: Endogenous tagging for the cartography of human cellular organization. Science (New York, N.Y.) 432 35271311
2005 Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes. Genome research 409 16344560
2015 Panorama of ancient metazoan macromolecular complexes. Nature 407 26344197
2002 Functional proteomic analysis of human nucleolus. Molecular biology of the cell 391 12429849
2011 Global identification of modular cullin-RING ligase substrates. Cell 354 21963094
2011 The SARS-coronavirus-host interactome: identification of cyclophilins as target for pan-coronavirus inhibitors. PLoS pathogens 341 22046132
2021 A proximity-dependent biotinylation map of a human cell. Nature 339 34079125
2010 Dynamics of cullin-RING ubiquitin ligase network revealed by systematic quantitative proteomics. Cell 318 21145461
2010 Mass spectrometric analysis of lysine ubiquitylation reveals promiscuity at site level. Molecular & cellular proteomics : MCP 262 21139048
2016 A High-Density Map for Navigating the Human Polycomb Complexome. Cell reports 216 27705803
2016 An organelle-specific protein landscape identifies novel diseases and molecular mechanisms. Nature communications 211 27173435
2018 An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations. Nature communications 201 29568061
2011 LAS1L interacts with the mammalian Rix1 complex to regulate ribosome biogenesis. Molecular biology of the cell 89 22190735
2015 Coordinated Ribosomal ITS2 RNA Processing by the Las1 Complex Integrating Endonuclease, Polynucleotide Kinase, and Exonuclease Activities. Molecular cell 84 26638174
2011 The evolutionarily conserved protein Las1 is required for pre-rRNA processing at both ends of ITS2. Molecular and cellular biology 66 22083961
2010 Las1L is a nucleolar protein required for cell proliferation and ribosome biogenesis. Molecular and cellular biology 56 20647540
2020 Circ_LAS1L regulates cardiac fibroblast activation, growth, and migration through miR-125b/SFRP5 pathway. Cell biochemistry and function 48 31950540
2012 Las1 interacts with Grc3 polynucleotide kinase and is required for ribosome synthesis in Saccharomyces cerevisiae. Nucleic acids research 40 23175604
1995 LAS1 is an essential nuclear protein involved in cell morphogenesis and cell surface growth. Genetics 36 8582632
2017 Grc3 programs the essential endoribonuclease Las1 for specific RNA cleavage. Proceedings of the National Academy of Sciences of the United States of America 33 28652339
2018 GAS5 promotes myocardial apoptosis in myocardial ischemia-reperfusion injury via upregulating LAS1 expression. European review for medical and pharmacological sciences 21 30556886
2020 It takes two (Las1 HEPN endoribonuclease domains) to cut RNA correctly. The Journal of biological chemistry 16 32220933
2018 Characterization of the molecular crosstalk within the essential Grc3/Las1 pre-rRNA processing complex. RNA (New York, N.Y.) 13 29440475
2022 Knockdown of hnRNPA1 Promotes NSCLC Metastasis and EMT by Regulating Alternative Splicing of LAS1L exon 9. Frontiers in oncology 9 35814393
2023 Covalent targeting the LAS1-NOL9 axis for selective treatment in NPM1 mutant acute myeloid leukemia. Pharmacological research 5 36796466
2024 USP36 SUMOylates Las1L and Promotes Its Function in Pre-Ribosomal RNA ITS2 Processing. Cancer research communications 4 39356143
2022 Severe Infantile Axonal Neuropathy with Respiratory Failure Caused by Novel Mutation in X-Linked LAS1L Gene. Genes 2 35627110