The Prolyl Isomerase Pin1 Targets Stem-Loop Binding Protein (SLBP) To Dissociate the SLBP-Histone mRNA Complex Linking Histone mRNA Decay with SLBP Ubiquitination

ABSTRACT The replication-dependent histone mRNAs, the only eukaryotic mRNAs that do not have poly(A) tails, are present only in S-phase cells. Coordinate posttranscriptional regulation of histone mRNAs is mediated by the stem-loop at the 3′ end of histone mRNAs. The protein that binds the 3′ end of histone mRNA, stem-loop binding protein (SLBP), is required for histone pre-mRNA processing and is involved in multiple aspects of histone mRNA metabolism. SLBP is also regulated during the cell cycle, accumulating as cells enter S phase and being rapidly degraded as cells exit S phase. Mutation of any residues in a TTP sequence (amino acids 60 to 62) or mutation of a consensus cyclin binding site (amino acids 99 to 104) stabilizes SLBP in G2 and mitosis. These two threonines are phosphorylated in late S phase, as determined by mass spectrometry (MS) of purified SLBP from late S-phase cells, triggering SLBP degradation. Cells that express a stable SLBP still degrade histone mRNA at the end of S phase, demonstrating that degradation of SLBP is not required for histone mRNA degradation. Nuclear extracts from G1 and G2 cells are deficient in histone pre-mRNA processing, which is restored by addition of recombinant SLBP, indicating that SLBP is the only cell cycle-regulated factor required for histone pre-mRNA processing.

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The sea urchin stem-loop-binding protein: a maternally expressed protein that probably functions in expression of multiple classes of histone mRNA

Nucleic Acids Research ◽

10.1093/nar/gkh193 ◽

2004 ◽

Vol 32 (2) ◽

pp. 811-818 ◽

Cited By ~ 8

Author(s):

A. J. Robertson

Keyword(s):

Sea Urchin ◽

Binding Protein ◽

Protein A ◽

Histone Mrna ◽

Stem Loop

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An oocyte-preferential histone mRNA stem-loop-binding protein like is expressed in several mammalian species

Molecular Reproduction and Development ◽

10.1002/mrd.22040 ◽

2012 ◽

Vol 79 (6) ◽

pp. 380-391 ◽

Cited By ~ 9

Author(s):

Aurore Thelie ◽

Geraldine Pascal ◽

Leslie Angulo ◽

Christine Perreau ◽

Pascal Papillier ◽

...

Keyword(s):

Binding Protein ◽

Mammalian Species ◽

Histone Mrna ◽

Stem Loop

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Structure of Histone mRNA Stem-Loop, Human Stem-Loop Binding Protein, and 3'hExo Ternary Complex

Science ◽

10.1126/science.1228705 ◽

2013 ◽

Vol 339 (6117) ◽

pp. 318-321 ◽

Cited By ~ 69

Author(s):

D. Tan ◽

W. F. Marzluff ◽

Z. Dominski ◽

L. Tong

Keyword(s):

Ternary Complex ◽

Binding Protein ◽

Histone Mrna ◽

Stem Loop

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Phosphorylation of Threonine 61 by Cyclin A/Cdk1 Triggers Degradation of Stem-Loop Binding Protein at the End of S Phase

Molecular and Cellular Biology ◽

10.1128/mcb.01416-07 ◽

2008 ◽

Vol 28 (14) ◽

pp. 4469-4479 ◽

Cited By ~ 44

Author(s):

M. Murat Koseoglu ◽

Lee M. Graves ◽

William F. Marzluff

Keyword(s):

Cell Cycle ◽

Fusion Proteins ◽

Regulatory Mechanism ◽

Binding Protein ◽

Cyclin A ◽

S Phase ◽

Mrna Levels ◽

Histone Mrna ◽

Stem Loop

ABSTRACT Histone mRNA levels are cell cycle regulated, and a major regulatory mechanism is restriction of stem-loop binding protein (SLBP) to S phase. Degradation of SLBP at the end of S phase results in cessation of histone mRNA biosynthesis, preventing accumulation of histone mRNA until SLBP is synthesized just before entry into the next S phase. Degradation of SLBP requires an SFTTP (58 to 62) and KRKL (95 to 98) sequence, which is a putative cyclin binding site. A fusion protein with the 58-amino-acid sequence of SLBP (amino acids 51 to 108) fused to glutathione S-transferase (GST) is sufficient to mimic SLBP degradation at late S phase. Using GST-SLBP fusion proteins as a substrate, we show that cyclin A/Cdk1 phosphorylates Thr61. Furthermore, knockdown of Cdk1 by RNA interference stabilizes SLBP at the end of S phase. Phosphorylation of Thr61 is necessary for subsequent phosphorylation of Thr60 by CK2 in vitro. Inhibitors of CK2 also prevent degradation of SLBP at the end of S phase. Thus, phosphorylation of Thr61 by cyclin A/Cdk1 primes phosphorylation of Thr60 by CK2 and is responsible for initiating SLBP degradation. We conclude that the increase in cyclin A/Cdk1 activity at the end of S phase triggers degradation of SLBP at S/G2.

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Molecular mechanisms for the regulation of histone mRNA stem-loop-binding protein by phosphorylation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1406381111 ◽

2014 ◽

Vol 111 (29) ◽

pp. E2937-E2946 ◽

Cited By ~ 14

Author(s):

J. Zhang ◽

D. Tan ◽

E. F. DeRose ◽

L. Perera ◽

Z. Dominski ◽

...

Keyword(s):

Molecular Mechanisms ◽

Binding Protein ◽

Histone Mrna ◽

Stem Loop

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Efficient Extraction and Partial Purification of the Polyribosome-Associated Stem−Loop Binding Protein Bound to the 3‘ End of Histone mRNA†

Biochemistry ◽

10.1021/bi9521856 ◽

1996 ◽

Vol 35 (7) ◽

pp. 2146-2156 ◽

Cited By ~ 28

Author(s):

Roberta J. Hanson ◽

Jianhua Sun ◽

Derall G. Willis ◽

William F. Marzluff

Keyword(s):

Binding Protein ◽

Partial Purification ◽

Histone Mrna ◽

Stem Loop ◽

Efficient Extraction

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Drosophila Stem-Loop Binding Protein Intracellular Localization Is Mediated by Phosphorylation and Is Required for Cell Cycle-regulated Histone mRNA Expression

Molecular Biology of the Cell ◽

10.1091/mbc.e03-09-0649 ◽

2004 ◽

Vol 15 (3) ◽

pp. 1112-1123 ◽

Cited By ~ 23

Author(s):

David J. Lanzotti ◽

Jeremy M. Kupsco ◽

Xiao-Cui Yang ◽

Zbigniew Dominski ◽

William F. Marzluff ◽

...

Keyword(s):

Cell Cycle ◽

Rna Binding ◽

Binding Protein ◽

Intracellular Localization ◽

Mrna Processing ◽

Nuclear Targeting ◽

Histone Mrna ◽

Stem Loop

Stem-loop binding protein (SLBP) is an essential component of the histone pre-mRNA processing machinery. SLBP protein expression was examined during Drosophila development by using transgenes expressing hemagglutinin (HA) epitope-tagged proteins expressed from the endogenous Slbp promoter. Full-length HA-dSLBP complemented a Slbp null mutation, demonstrating that it was fully functional. dSLBP protein accumulates throughout the cell cycle, in contrast to the observed restriction of mammalian SLBP to S phase. dSLBP is located in both nucleus and cytoplasm in replicating cells, but it becomes predominantly nuclear during G2. dSLBP is present in mitotic cells and is down-regulated in G1 when cells exit the cell cycle. We determined whether mutation at previously identified phosphorylation sites, T120 and T230, affected the ability of the protein to restore viability and histone mRNA processing to dSLBP null mutants. The T120A SLBP restored viability and histone pre-mRNA processing. However, the T230A mutant, located in a conserved TPNK sequence in the RNA binding domain, did not restore viability and histone mRNA processing in vivo, although it had full activity in histone mRNA processing in vitro. The T230A protein is concentrated in the cytoplasm, suggesting that it is defective in nuclear targeting, and accounting for its failure to function in histone pre-mRNA processing in vivo.

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