SF1 Phosphorylation Enhances Specific Binding to U2AF 65 and Reduces Binding to 3′-Splice-Site RNA

Chatrikhi, Rakesh; Wang, Wenhua; Gupta, Ankit; Loerch, Sarah; Maucuer, Alexandre; Kielkopf, Clara L.

doi:10.1016/j.bpj.2016.11.007

Cited by 20 publications

(21 citation statements)

References 71 publications

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“…Despite a bundle of phospho-proteins that have been proposed as substrates [32,36,[39][40][41][42][43][44], it is still unclear regarding the key downstream signaling pathway(s) perturbed by UHMK1 during tumorigenesis and progression. However, by mining the downstream targets of UHMK1 kinase activity, ERK2 and Stathmin1 were identified harboring the most significant changes of phosphorylation status (Table 1).…”

Section: Discussionmentioning

confidence: 99%

COX5B-Mediated Bioenergetic Alteration Regulates Tumor Growth and Migration by Modulating AMPK-UHMK1-ERK Cascade in Hepatoma

Chu

Lin

et al. 2020

Cancers

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The oxidative phosphorylation machinery in mitochondria, which generates the main bioenergy pool in cells, includes four enzyme complexes for electron transport and ATP synthase. Among them, the cytochrome c oxidase (COX), which constitutes the fourth complex, has been suggested as the major regulatory site. Recently, abnormalities in COX were linked to tumor progression in several cancers. However, it remains unclear whether COX and its subunits play a role in tumor progression of hepatoma. To search for the key regulatory factor(s) in COX for hepatoma development, in silico analysis using public transcriptomic database followed by validation for postoperative outcome associations using independent in-house patient cohorts was performed. In which, COX5B was highly expressed in hepatoma and associated with unfavorable postoperative prognosis. In addressing the role of COX5B in hepatoma, the loss- and gain-of-function experiments for COX5B were conducted. Consequently, COX5B expression was associated with increased hepatoma cell proliferation, migration and xenograft growth. Downstream effectors searched by cDNA microarray analysis identified UHMK1, an oncogenic protein, which manifested a positively correlated expression level of COX5B. The COX5B-mediated regulatory event on UHMK1 expression was subsequently demonstrated as bioenergetic alteration-dependent activation of AMPK in hepatoma cells. Phosphoproteomic analysis uncovered activation of ERK- and stathmin-mediated pathways downstream of UHMK1. Finally, comprehensive phenotypic assays supported the impacts of COX5B-UHMK1-ERK axis on hepatoma cell growth and migration.

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Section: Discussionmentioning

confidence: 99%

COX5B-Mediated Bioenergetic Alteration Regulates Tumor Growth and Migration by Modulating AMPK-UHMK1-ERK Cascade in Hepatoma

Chu

Lin

et al. 2020

Cancers

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“…To avoid overlapping molecular weights, we conversely compared GST-Tat-SF1 retention of SF3b1 ULM with SF1. The SF1 protein was phosphorylated (P) in vitro with UHMK1 as described (25,36), which subtly enhances SF1-U2AF 65 association (36,37) and is the major form of SF1 in proliferating cells (36,38).…”

Section: Tat-sf1 Preferentially and Directly Binds Sf3b1 Compared Witmentioning

confidence: 99%

The pre-mRNA splicing and transcription factor Tat-SF1 is a functional partner of the spliceosome SF3b1 subunit via a U2AF homology motif interface

Loerch¹,

Leach

Horner³

et al. 2019

Journal of Biological Chemistry

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Edited by Karin Musier-ForsythThe transcription elongation and pre-mRNA splicing factor Tat-SF1 associates with the U2 small nuclear ribonucleoprotein (snRNP) of the spliceosome. However, the direct binding partner and underlying interactions mediating the Tat-SF1-U2 snRNP association remain unknown. Here, we identified SF3b1 as a Tat-SF1-interacting subunit of the U2 snRNP. Our 1.1 Å resolution crystal structure revealed that Tat-SF1 contains a U2AF homology motif (UHM) protein-protein interaction module. We demonstrated that Tat-SF1 preferentially and directly binds the SF3b1 subunit compared with other U2AF ligand motif (ULM)-containing splicing factors, and further established that SF3b1 association depends on the integrity of the Tat-SF1 UHM. We next compared the Tat-SF1-binding affinities for each of the five known SF3b1 ULMs and then determined the structures of representative high-and low-affinity SF3b1 ULM complexes with the Tat-SF1 UHM at 1.9 Å and 2.1 Å resolutions, respectively. These structures revealed a canonical UHM-ULM interface, comprising a Tat-SF1 binding pocket for a ULM tryptophan (SF3b1 Trp 338 ) and electrostatic interactions with a basic ULM tail. Importantly, we found that SF3b1 regulates Tat-SF1 levels and that these two factors influence expression of overlapping representative transcripts, consistent with a functional partnership of Tat-SF1 and SF3b1. Altogether, these results define a new molecular interface of the Tat-SF1-U2 snRNP complex for gene regulation.Tat stimulatory factor 1 (Tat-SF1) 4 was originally identified as a host cofactor that activates Tat-directed HIV-1 transcrip-tion (1, 2). Subsequent studies revealed that Tat-SF1 normally stimulates human transcription elongation (3, 4) as a complex with P-TEFb, SPT5, and RAP30 (2, 5-7). The Saccharomyces cerevisiae Tat-SF1 homologue, CUS2, promotes transcription elongation in combination with the RNA unwindases PRP5 and PRP11 (8). Beyond transcription, CUS2 is well-established as an assembly factor for the U2 small nuclear (sn)RNA in the early stages of pre-mRNA splicing (9 -13). Like CUS2, human Tat-SF1 influences pre-mRNA splicing (14 -18). Reduced Tat-SF1 levels typically promote intron retention rather than exon-skipping or alternative splice sites. Most recently, critical Tat-SF1 functions in pre-mRNA splicing have emerged for embryonic stem cell differentiation (17,18).Tat-SF1 co-immunoprecipitates with the U2 small nuclear ribonucleoprotein particle (17)(18)(19)(20), which anneals with the pre-mRNA branch point site in the early steps of spliceosome assembly. Yet, the direct interaction partner(s) of Tat-SF1 in the human spliceosome remains unknown. Clues arise from experimental observations coupled with the primary sequences of Tat-SF1 and the U2 snRNP components. Primary sequence analysis suggests that Tat-SF1 contains two modular domains, an RNA recognition motif (RRM) and a U2AF homology motif (UHM) (Fig. 1A). The UHM is a protein-interaction module with specialized features for recognizing short "U2AF ligand motifs...

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“…Through the UHM motif, UHMK1 interacts with the splicing factors SF1 and SF3B1 (Manceau et al, 2008). Upon interaction, UHMK1 phosphorylates SF1, which enhances SF1 specific binding to U2AF 65 and reduces the SF1-U2AF 65 binding to the 3' splice site RNA (Chatrikhi et al, 2016;Manceau et al, 2006). In addition, UHMK1…”

Section: Functionmentioning

confidence: 99%

UHMK1 (U2AF homology motif kinase 1)

Arfelli¹,

Archangelo²

2018

Atlas of Genetics and Cytogenetics in Oncology and Haematology

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UHMK1 (also known as KIS) is a serine/threonine kinase initially identified as a Stathmin interacting protein. UHMK1 is characterized by an N-terminal kinase domain and a C-terminal UHM motif. Through the UHM motif, the protein is capable of interacting with splicing factors, such as SF1 and SF3B1, involved in early steps of spliceosome assembly. UHMK1 is ubiquitously but preferentially expressed in the developing nervous system, where it plays a role in mRNA processing, translational enhancing, neurite outgrowth and postsynaptic plasticity. Protein interactions between UHMK1 and a range of proteins pointed to its function in different cellular processes, such as RNA metabolism, cell cycle progression, cell migration and membrane trafficking. More recently, a role of UHMK1 in cell differentiation has also been proposed.

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SF1 Phosphorylation Enhances Specific Binding to U2AF 65 and Reduces Binding to 3′-Splice-Site RNA

Cited by 20 publications

References 71 publications

COX5B-Mediated Bioenergetic Alteration Regulates Tumor Growth and Migration by Modulating AMPK-UHMK1-ERK Cascade in Hepatoma

COX5B-Mediated Bioenergetic Alteration Regulates Tumor Growth and Migration by Modulating AMPK-UHMK1-ERK Cascade in Hepatoma

The pre-mRNA splicing and transcription factor Tat-SF1 is a functional partner of the spliceosome SF3b1 subunit via a U2AF homology motif interface

UHMK1 (U2AF homology motif kinase 1)

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