scholarly journals Developmental and Cell Cycle Regulation of the Drosophila Histone Locus Body

2007 ◽  
Vol 18 (7) ◽  
pp. 2491-2502 ◽  
Author(s):  
Anne E. White ◽  
Michelle E. Leslie ◽  
Brian R. Calvi ◽  
William F. Marzluff ◽  
Robert J. Duronio
Keyword(s):  
Cyclin E ◽  
Early Embryo ◽  
Cajal Body ◽  
Histone Mrna ◽  
Small Nuclear Ribonucleoprotein ◽  
Histone Locus Body ◽  
Histone Transcription ◽  
Nuclear Ribonucleoprotein ◽  
Histone Locus ◽  
Cycle Regulation

Cyclin E/Cdk2 is necessary for replication-dependent histone mRNA biosynthesis, but how it controls this process in early development is unknown. We show that in Drosophila embryos the MPM-2 monoclonal antibody, raised against a phosphoepitope from human mitotic cells, detects Cyclin E/Cdk2-dependent nuclear foci that colocalize with nascent histone transcripts. These foci are coincident with the histone locus body (HLB), a Cajal body-like nuclear structure associated with the histone locus and enriched in histone pre-mRNA processing factors such as Lsm11, a core component of the U7 small nuclear ribonucleoprotein. Using MPM-2 and anti-Lsm11 antibodies, we demonstrate that the HLB is absent in the early embryo and occurs when zygotic histone transcription begins during nuclear cycle 11. Whereas the HLB is found in all cells after its formation, MPM-2 labels the HLB only in cells with active Cyclin E/Cdk2. MPM-2 and Lsm11 foci are present in embryos lacking the histone locus, and MPM-2 foci are present in U7 mutants, which cannot correctly process histone pre-mRNA. These data indicate that MPM-2 recognizes a Cdk2-regulated protein that assembles into the HLB independently of histone mRNA biosynthesis. HLB foci are present in histone deletion embryos, although the MPM-2 foci are smaller, and some Lsm11 foci are not associated with MPM-2 foci, suggesting that the histone locus is important for HLB integrity.

scholarly journals Concentrating pre-mRNA processing factors in the histone locus body facilitates efficient histone mRNA biogenesis

2016 ◽  
Vol 213 (5) ◽  
pp. 557-570 ◽  
Author(s):  
Deirdre C. Tatomer ◽  
Esteban Terzo ◽  
Kaitlin P. Curry ◽  
Harmony Salzler ◽  
Ivan Sabath ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Mrna Processing ◽  
Histone Mrna ◽  
Histone Mrnas ◽  
Assembly Factor ◽  
U7 Snrnp ◽  
Histone Locus Body ◽  
Histone Locus ◽  
Processing Factors

The histone locus body (HLB) assembles at replication-dependent histone genes and concentrates factors required for histone messenger RNA (mRNA) biosynthesis. FLASH (Flice-associated huge protein) and U7 small nuclear RNP (snRNP) are HLB components that participate in 3′ processing of the nonpolyadenylated histone mRNAs by recruiting the endonuclease CPSF-73 to histone pre-mRNA. Using transgenes to complement a FLASH mutant, we show that distinct domains of FLASH involved in U7 snRNP binding, histone pre-mRNA cleavage, and HLB localization are all required for proper FLASH function in vivo. By genetically manipulating HLB composition using mutations in FLASH, mutations in the HLB assembly factor Mxc, or depletion of the variant histone H2aV, we find that failure to concentrate FLASH and/or U7 snRNP in the HLB impairs histone pre-mRNA processing. This failure results in accumulation of small amounts of polyadenylated histone mRNA and nascent read-through transcripts at the histone locus. Thus, the HLB concentrates FLASH and U7 snRNP, promoting efficient histone mRNA biosynthesis and coupling 3′ end processing with transcription termination.

Functional analysis of the sea urchin U7 small nuclear RNA

1988 ◽  
Vol 8 (3) ◽  
pp. 1076-1084
Author(s):  
G M Gilmartin ◽  
F Schaufele ◽  
G Schaffner ◽  
M L Birnstiel
Keyword(s):  
Sea Urchin ◽  
Micrococcal Nuclease ◽  
Small Nuclear Rna ◽  
Histone Mrna ◽  
Small Nuclear Ribonucleoprotein ◽  
Nuclear Rna ◽  
U7 Snrnp ◽  
Structure Relationship ◽  
Nuclear Ribonucleoprotein ◽  
Sm Protein

U7 small nuclear RNA (snRNA) is an essential component of the RNA-processing machinery which generates the 3' end of mature histone mRNA in the sea urchin. The U7 small nuclear ribonucleoprotein particle (snRNP) is classified as a member of the Sm-type U snRNP family by virtue of its recognition by both anti-trimethylguanosine and anti-Sm antibodies. We analyzed the function-structure relationship of the U7 snRNP by mutagenesis experiments. These suggested that the U7 snRNP of the sea urchin is composed of three important domains. The first domain encompasses the 5'-terminal sequences, up to about nucleotides 7, which are accessible to micrococcal nuclease, while the remainder of the RNA is highly protected and hence presumably bound by proteins. This region contains the sequence complementarities between the U7 snRNA and the histone pre-mRNA which have previously been shown to be required for 3' processing (F. Schaufele, G. M. Gilmartin, W. Bannwarth, and M. L. Birnstiel, Nature [London] 323:777-781, 1986). Nucleotides 9 to 20 constitute a second domain which includes sequences for Sm protein binding. The complementarities between the U7 snRNA sequences in this region and the terminal palindrome of the histone mRNA appear to be fortuitous and play only a secondary, if any, role in 3' processing. The third domain is composed of the terminal palindrome of U7 snRNA, the secondary structure of which must be maintained for the U7 snRNP to function, but its sequence can be drastically altered without any observable effect on snRNP assembly or 3' processing.

scholarly journals Functional analysis of the sea urchin U7 small nuclear RNA.

1988 ◽  
Vol 8 (3) ◽  
pp. 1076-1084 ◽  
Author(s):  
G M Gilmartin ◽  
F Schaufele ◽  
G Schaffner ◽  
M L Birnstiel
Keyword(s):  
Sea Urchin ◽  
Micrococcal Nuclease ◽  
Small Nuclear Rna ◽  
Histone Mrna ◽  
Small Nuclear Ribonucleoprotein ◽  
Nuclear Rna ◽  
U7 Snrnp ◽  
Structure Relationship ◽  
Nuclear Ribonucleoprotein ◽  
Sm Protein

U7 small nuclear RNA (snRNA) is an essential component of the RNA-processing machinery which generates the 3' end of mature histone mRNA in the sea urchin. The U7 small nuclear ribonucleoprotein particle (snRNP) is classified as a member of the Sm-type U snRNP family by virtue of its recognition by both anti-trimethylguanosine and anti-Sm antibodies. We analyzed the function-structure relationship of the U7 snRNP by mutagenesis experiments. These suggested that the U7 snRNP of the sea urchin is composed of three important domains. The first domain encompasses the 5'-terminal sequences, up to about nucleotides 7, which are accessible to micrococcal nuclease, while the remainder of the RNA is highly protected and hence presumably bound by proteins. This region contains the sequence complementarities between the U7 snRNA and the histone pre-mRNA which have previously been shown to be required for 3' processing (F. Schaufele, G. M. Gilmartin, W. Bannwarth, and M. L. Birnstiel, Nature [London] 323:777-781, 1986). Nucleotides 9 to 20 constitute a second domain which includes sequences for Sm protein binding. The complementarities between the U7 snRNA sequences in this region and the terminal palindrome of the histone mRNA appear to be fortuitous and play only a secondary, if any, role in 3' processing. The third domain is composed of the terminal palindrome of U7 snRNA, the secondary structure of which must be maintained for the U7 snRNP to function, but its sequence can be drastically altered without any observable effect on snRNP assembly or 3' processing.

scholarly journals The Cyclin E/Cdk2 Substrate p220NPAT Is Required for S-Phase Entry, Histone Gene Expression, and Cajal Body Maintenance in Human Somatic Cells

2003 ◽  
Vol 23 (23) ◽  
pp. 8586-8600 ◽  
Author(s):  
Xin Ye ◽  
Yue Wei ◽  
Grzegorz Nalepa ◽  
J. Wade Harper
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Cyclin E ◽  
S Phase ◽  
Cajal Body ◽  
Histone H4 ◽  
Cycle Arrest ◽  
Histone Transcription ◽  
Phase Entry ◽  
Hct116 Cells

ABSTRACT Cyclin E/Cdk2, a central regulator of the G1/S transition, coordinates multiple cell cycle events, including DNA replication, centrosome duplication, and activation of the E2F transcriptional program. Recent studies suggest a role for cyclin E/Cdk2 in activation of histone transcription during S phase via the Cajal body-associated protein p220NPAT, and in addition, p220 can promote S-phase entry independently of histone transcriptional activation when overexpressed. Here we have examined the requirement for p220 in histone transcription, cell cycle progression, and Cajal body function through analysis of human somatic HCT116 cells engineered to contain a conditional p220 allele. p220 is required for proliferation of HCT116 cells, as assessed after expression of Cre recombinase in p220flox/− cells. This defect was due to an inability of these cells to transit from G0/G1 into S phase, and cell cycle arrest occurred in the presence of elevated Cdk2 kinase activity. Expression of human papillomavirus E7, but not E6, eliminated cell cycle arrest in response to p220 depletion. Optimal expression of all four core histone genes required p220, as did optimal transcription of a histone H4 promoter-luciferase construct. Basal histone H4 expression in G0/G1, although p220 dependent, occurs in the absence of detectable phosphorylation of p220 on Cdk2 sites. Cells lacking p220 displayed defects in the localization of the Cajal body component p80coilin as cells progressed from G0 to S phase in response to mitogenic signals. These finding indicate that p220 is an essential downstream component of the cyclin E/Cdk2 signaling pathway and functions to coordinate multiple elements of the G1/S transition.

scholarly journals Spliceosomal Small Nuclear Ribonucleoprotein Particles Repeatedly Cycle through Cajal Bodies

2008 ◽  
Vol 19 (6) ◽  
pp. 2534-2543 ◽  
Author(s):  
David Staněk ◽  
Jarmila Přidalová-Hnilicová ◽  
Ivan Novotný ◽  
Martina Huranová ◽  
Michaela Blažíková ◽  
...  
Keyword(s):  
Fluorescent Proteins ◽  
Living Cells ◽  
Cajal Body ◽  
Cajal Bodies ◽  
Sm Proteins ◽  
Small Nuclear Ribonucleoprotein ◽  
Ribonucleoprotein Particles ◽  
Nuclear Extracts ◽  
Nuclear Ribonucleoprotein ◽  
Interfering Rna

The Cajal body (CB) is a nuclear structure closely associated with import and biogenesis of small nuclear ribonucleoprotein particles (snRNPs). Here, we tested whether CBs also contain mature snRNPs and whether CB integrity depends on the ongoing snRNP splicing cycle. Sm proteins tagged with photoactivatable and color-maturing variants of fluorescent proteins were used to monitor snRNP behavior in living cells over time; mature snRNPs accumulated in CBs, traveled from one CB to another, and they were not preferentially replaced by newly imported snRNPs. To test whether CB integrity depends on the snRNP splicing cycle, two human orthologues of yeast proteins involved in distinct steps in spliceosome disassembly after splicing, hPrp22 and hNtr1, were depleted by small interfering RNA treatment. Surprisingly, depletion of either protein led to the accumulation of U4/U6 snRNPs in CBs, suggesting that reassembly of the U4/U6·U5 tri-snRNP was delayed. Accordingly, a relative decrease in U5 snRNPs compared with U4/U6 snRNPs was observed in CBs, as well as in nuclear extracts of treated cells. Together, the data show that particular phases of the spliceosome cycle are compartmentalized in living cells, with reassembly of the tri-snRNP occurring in CBs.

scholarly journals Distinct self-interaction domains promote Multi Sex Combs accumulation in and formation of the Drosophila histone locus body

2015 ◽  
Vol 26 (8) ◽  
pp. 1559-1574 ◽  
Author(s):  
Esteban A. Terzo ◽  
Shawn M. Lyons ◽  
John S. Poulton ◽  
Brenda R. S. Temple ◽  
William F. Marzluff ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nuclear Bodies ◽  
Confocal Imaging ◽  
Histone Mrna ◽  
Mrna Accumulation ◽  
Sex Combs ◽  
Histone Locus Body ◽  
Histone Locus ◽  
Multiple Domains

Nuclear bodies (NBs) are structures that concentrate proteins, RNAs, and ribonucleoproteins that perform functions essential to gene expression. How NBs assemble is not well understood. We studied the Drosophila histone locus body (HLB), a NB that concentrates factors required for histone mRNA biosynthesis at the replication-dependent histone gene locus. We coupled biochemical analysis with confocal imaging of both fixed and live tissues to demonstrate that the Drosophila Multi Sex Combs (Mxc) protein contains multiple domains necessary for HLB assembly. An important feature of this assembly process is the self-interaction of Mxc via two conserved N-terminal domains: a LisH domain and a novel self-interaction facilitator (SIF) domain immediately downstream of the LisH domain. Molecular modeling suggests that the LisH and SIF domains directly interact, and mutation of either the LisH or the SIF domain severely impairs Mxc function in vivo, resulting in reduced histone mRNA accumulation. A region of Mxc between amino acids 721 and 1481 is also necessary for HLB assembly independent of the LisH and SIF domains. Finally, the C-terminal 195 amino acids of Mxc are required for recruiting FLASH, an essential histone mRNA-processing factor, to the HLB. We conclude that multiple domains of the Mxc protein promote HLB assembly in order to concentrate factors required for histone mRNA biosynthesis.

scholarly journals Identification and characterization ofDrosophilaSnurportin reveals a role for the import receptor Moleskin/importin-7 in snRNP biogenesis

2013 ◽  
Vol 24 (18) ◽  
pp. 2932-2942 ◽  
Author(s):  
Amanda Hicks Natalizio ◽  
A. Gregory Matera
Keyword(s):  
Fruit Fly ◽  
Survival Motor Neuron ◽  
Cajal Body ◽  
Small Nuclear Ribonucleoprotein ◽  
Small Nuclear Rnas ◽  
Assembly Factor ◽  
Nuclear Ribonucleoprotein ◽  
Identification And Characterization ◽  
Transport Receptor ◽  
Import Receptor

Nuclear import is an essential step in small nuclear ribonucleoprotein (snRNP) biogenesis. Snurportin1 (SPN1), the import adaptor, binds to trimethylguanosine (TMG) caps on spliceosomal small nuclear RNAs. Previous studies indicated that vertebrate snRNP import requires importin-β, the transport receptor that binds directly to SPN1. We identify CG42303/snup as the Drosophila orthologue of human snurportin1 (SNUPN). Of interest, the importin-β binding (IBB) domain of SPN1, which is essential for TMG cap–mediated snRNP import in humans, is not well conserved in flies. Consistent with its lack of an IBB domain, we find that Drosophila SNUP (dSNUP) does not interact with Ketel/importin-β. Fruit fly snRNPs also fail to bind Ketel; however, the importin-7 orthologue Moleskin (Msk) physically associates with both dSNUP and spliceosomal snRNPs and localizes to nuclear Cajal bodies. Strikingly, we find that msk-null mutants are depleted of the snRNP assembly factor, survival motor neuron, and the Cajal body marker, coilin. Consistent with a loss of snRNP import function, long-lived msk larvae show an accumulation of TMG cap signal in the cytoplasm. These data indicate that Ketel/importin-β does not play a significant role in Drosophila snRNP import and demonstrate a crucial function for Msk in snRNP biogenesis.

scholarly journals The Cajal Body and Histone Locus Body

2010 ◽  
Vol 2 (7) ◽  
pp. a000653-a000653 ◽  
Author(s):  
Z. Nizami ◽  
S. Deryusheva ◽  
J. G. Gall
Keyword(s):  
Cajal Body ◽  
Histone Locus Body ◽  
Histone Locus

scholarly journals Drosophila Histone Locus Body assembly and function involves multiple interactions

2020 ◽  
Author(s):  
Kaitlin P. Koreski ◽  
Leila E. Rieder ◽  
Lyndsey M. McLain ◽  
William F. Marzluff ◽  
Robert J. Duronio
Keyword(s):  
Gene Expression ◽  
Repeat Unit ◽  
Gene Array ◽  
Homozygous Deletion ◽  
Histone Gene ◽  
Histone Genes ◽  
Histone Mrna ◽  
Histone Gene Expression ◽  
Histone Locus Body ◽  
Histone Locus

AbstractThe histone locus body (HLB) assembles at replication-dependent (RD) histone loci and concentrates factors required for RD histone mRNA biosynthesis. The D. melanogaster genome has a single locus comprised of ∼100 copies of a tandemly arrayed repeat unit containing one copy of each of the 5 RD histone genes. To determine sequence elements required for D. melanogaster HLB formation and histone gene expression, we used transgenic gene arrays containing 12 copies of the histone repeat unit that functionally complement loss of the ∼200 endogenous RD histone genes. A 12x histone gene array in which all H3-H4 promoters were replaced with H2a-H2b promoters does not form an HLB or express high levels of RD histone mRNA in the presence of the endogenous histone genes. In contrast, this same transgenic array is active in HLB assembly and RD histone gene expression in the absence of the endogenous RD histone genes and rescues the lethality caused by homozygous deletion of the RD histone locus. The HLB formed in the absence of endogenous RD histone genes on the mutant 12x array contains all known factors present in the wild type HLB including CLAMP, which normally binds to GAGA repeats in the H3-H4 promoter. These data suggest that multiple protein-protein and/or protein-DNA interactions contribute to HLB formation, and that the large number of endogenous RD histone gene copies sequester available factor(s) from attenuated transgenic arrays, thereby preventing HLB formation and gene expression.

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