1
|
Sybilska E, Daszkowska-Golec A. Alternative splicing in ABA signaling during seed germination. FRONTIERS IN PLANT SCIENCE 2023; 14:1144990. [PMID: 37008485 PMCID: PMC10060653 DOI: 10.3389/fpls.2023.1144990] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
Seed germination is an essential step in a plant's life cycle. It is controlled by complex physiological, biochemical, and molecular mechanisms and external factors. Alternative splicing (AS) is a co-transcriptional mechanism that regulates gene expression and produces multiple mRNA variants from a single gene to modulate transcriptome diversity. However, little is known about the effect of AS on the function of generated protein isoforms. The latest reports indicate that alternative splicing (AS), the relevant mechanism controlling gene expression, plays a significant role in abscisic acid (ABA) signaling. In this review, we present the current state of the art about the identified AS regulators and the ABA-related changes in AS during seed germination. We show how they are connected with the ABA signaling and the seed germination process. We also discuss changes in the structure of the generated AS isoforms and their impact on the functionality of the generated proteins. Also, we point out that the advances in sequencing technology allow for a better explanation of the role of AS in gene regulation by more accurate detection of AS events and identification of full-length splicing isoforms.
Collapse
|
2
|
Mabonga L, Ikwegbue PC, Masamba P, Kappo AP. Molecular interaction between small nuclear ribonucleoprotein polypeptide G and heat shock protein 70.14: a microscale thermophoresis exposition towards developing anti-cancer drugs. Am J Transl Res 2022; 14:6150-6162. [PMID: 36247303 PMCID: PMC9556510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Targeting protein-protein interactions (PPIs) linked to protein quality control (PQC) pathways as potential anti-cancer drug targets have unanimously widened biological insights and the therapeutic potential of PPIs as smart-drug discovery tools in cancer. PPIs between disease-relevant proteins associated with protein homeostasis in PQC pathways have been linked to improved mechanistic understanding associated with conformational abnormalities and impairment, cellular proteotoxicity, induced apoptosis, and pathogenesis in different types of cancers. In this context, PPIs between small nuclear ribonucleoprotein polypeptide G (SNRPG) and heat shock protein 70.14 (Hsp70.14) have attracted attention as potential smart drug discovery tools in cancer diagnostics and therapeutics. Validated evidence of high-quality biological data has shown the presence of the two proteins in different types of cancers including breast cancer. The links between SNRPG and Hsp70.14 in cancer-cell networks remain elusive, overlooked, and uncharacterized. METHODOLOGY In this study, we explored the interaction between the two oncogenic proteins using the MST-based assays. RESULTS The results revealed a low KD in the nanomolar concentration range of 2.4673 × 10-7 demonstrating a great affinity for SNRPG binding to Hsp70.14. CONCLUSIONS The results suggest a possible involvement between the two proteins in hostile tumour microenvironments. Furthermore, these findings offer a different therapeutic perspective that could pave the way for the creation of novel small molecule inhibitors as drugs for the treatment of cancer.
Collapse
Affiliation(s)
- Lloyd Mabonga
- Department of Biochemistry and Microbiology, University of ZululandKwaDlangezwa 3886, South Africa
| | - Paul Chukwudi Ikwegbue
- Division of Immunology, Department of Pathology, Faculty of Health Sciences, University of Cape TownCape Town, South Africa
| | - Priscilla Masamba
- Molecular Biophysics and Structural Biology (MBSB) Group, Department of Biochemistry, Faculty of Science, University of Johannesburg, Auckland Park Kingsway CampusSouth Africa
| | - Abidemi Paul Kappo
- Molecular Biophysics and Structural Biology (MBSB) Group, Department of Biochemistry, Faculty of Science, University of Johannesburg, Auckland Park Kingsway CampusSouth Africa
| |
Collapse
|
3
|
Biology of the mRNA Splicing Machinery and Its Dysregulation in Cancer Providing Therapeutic Opportunities. Int J Mol Sci 2021; 22:ijms22105110. [PMID: 34065983 PMCID: PMC8150589 DOI: 10.3390/ijms22105110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022] Open
Abstract
Dysregulation of messenger RNA (mRNA) processing—in particular mRNA splicing—is a hallmark of cancer. Compared to normal cells, cancer cells frequently present aberrant mRNA splicing, which promotes cancer progression and treatment resistance. This hallmark provides opportunities for developing new targeted cancer treatments. Splicing of precursor mRNA into mature mRNA is executed by a dynamic complex of proteins and small RNAs called the spliceosome. Spliceosomes are part of the supraspliceosome, a macromolecular structure where all co-transcriptional mRNA processing activities in the cell nucleus are coordinated. Here we review the biology of the mRNA splicing machinery in the context of other mRNA processing activities in the supraspliceosome and present current knowledge of its dysregulation in lung cancer. In addition, we review investigations to discover therapeutic targets in the spliceosome and give an overview of inhibitors and modulators of the mRNA splicing process identified so far. Together, this provides insight into the value of targeting the spliceosome as a possible new treatment for lung cancer.
Collapse
|
4
|
van der Feltz C, Hoskins AA. Structural and functional modularity of the U2 snRNP in pre-mRNA splicing. Crit Rev Biochem Mol Biol 2019; 54:443-465. [PMID: 31744343 DOI: 10.1080/10409238.2019.1691497] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The U2 small nuclear ribonucleoprotein (snRNP) is an essential component of the spliceosome, the cellular machine responsible for removing introns from precursor mRNAs (pre-mRNAs) in all eukaryotes. U2 is an extraordinarily dynamic splicing factor and the most frequently mutated in cancers. Cryo-electron microscopy (cryo-EM) has transformed our structural and functional understanding of the role of U2 in splicing. In this review, we synthesize these and other data with respect to a view of U2 as an assembly of interconnected functional modules. These modules are organized by the U2 small nuclear RNA (snRNA) for roles in spliceosome assembly, intron substrate recognition, and protein scaffolding. We describe new discoveries regarding the structure of U2 components and how the snRNP undergoes numerous conformational and compositional changes during splicing. We specifically highlight large scale movements of U2 modules as the spliceosome creates and rearranges its active site. U2 serves as a compelling example for how cellular machines can exploit the modular organization and structural plasticity of an RNP.
Collapse
Affiliation(s)
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| |
Collapse
|
5
|
Mabonga L, Kappo AP. The oncogenic potential of small nuclear ribonucleoprotein polypeptide G: a comprehensive and perspective view. Am J Transl Res 2019; 11:6702-6716. [PMID: 31814883 PMCID: PMC6895504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 10/19/2019] [Indexed: 06/10/2023]
Abstract
Small nuclear ribonucleoprotein polypeptide G (SNRPG), often referred to as Smith protein G (SmG), is an indispensable component in the biogenesis of spliceosomal uridyl-rich small nuclear ribonucleoprotein particles (U snRNPs; U1, U2, U4 and U5), which are precursors of both the major and minor spliceosome. SNRPG has attracted significant attention because of its implicated roles in tumorigenesis and tumor development. Suggestive evidence of its varying expression levels has been reported in different types of cancers, which include breast cancer, lung cancer, prostate cancer and colon cancer. The accumulating evidence suggests that the splicing machinery component plays a significant role in the initiation and progression of cancers. SNRPG has a wide interaction network, and its functions are predominantly mediated by protein-protein interactions (PPIs), making it a promising anti-cancer therapeutic target in PPI-focused drug technology. Understanding its roles in tumorigenesis and tumor development is an indispensable arsenal in the development of molecular-targeted therapies. Several antitumor drugs linked to splicing machinery components have been reported in different types of cancers and some have already entered the clinic. However, targeting SNRPG as a drug development tool has been an overlooked and underdeveloped strategy in cancer therapy. In this article, we present a comprehensive and perspective view on the oncogenic potential of SNRPG in PPI-focused drug discovery.
Collapse
|
6
|
Domain Requirements and Genetic Interactions of the Mud1 Subunit of the Saccharomyces cerevisiae U1 snRNP. G3-GENES GENOMES GENETICS 2019; 9:145-151. [PMID: 30413416 PMCID: PMC6325900 DOI: 10.1534/g3.118.200781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mud1 is an inessential 298-amino acid protein subunit of the Saccharomyces cerevisiae U1 snRNP. Mud1 consists of N-terminal and C-terminal RRM domains (RRM1 and RRM2) separated by a linker domain. Synthetic lethal interactions of mud1∆ with deletions of inessential spliceosome components Nam8, Mud2, and Msl1, or missense mutations in the branchpoint-binding protein Msl5 enabled us to dissect genetically the domain requirements for Mud1 function. We find that the biological activities of Mud1 can be complemented by co-expressing separately the RRM1 (aa 1-127) and linker-RRM2 (aa 128-298) modules. Whereas RRM1 and RRM2 (aa 197-298) per se are inactive in all tests of functional complementation, the linker-RRM2 by itself partially complements a subset of synthetic lethal mud1∆ interactions. Linker segment aa 155 to 196 contains a nuclear localization signal rich in basic amino acids that is necessary for RRM2 activity in mud1∆ complementation. Alanine scanning mutagenesis indicates that none of the individual RRM1 amino acid contacts to U1 snRNA in the cryo-EM model of the yeast U1 snRNP is necessary for mud1∆ complementation activity.
Collapse
|
7
|
Roth AJ, Shuman S, Schwer B. Defining essential elements and genetic interactions of the yeast Lsm2-8 ring and demonstration that essentiality of Lsm2-8 is bypassed via overexpression of U6 snRNA or the U6 snRNP subunit Prp24. RNA (NEW YORK, N.Y.) 2018; 24:853-864. [PMID: 29615482 PMCID: PMC5959253 DOI: 10.1261/rna.066175.118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
A seven-subunit Lsm2-8 protein ring assembles on the U-rich 3' end of the U6 snRNA. A structure-guided mutational analysis of the Saccharomyces cerevisiae Lsm2-8 ring affords new insights to structure-function relations and genetic interactions of the Lsm subunits. Alanine scanning of 39 amino acids comprising the RNA-binding sites or intersubunit interfaces of Lsm2, Lsm3, Lsm4, Lsm5, and Lsm8 identified only one instance of lethality (Lsm3-R69A) and one severe growth defect (Lsm2-R63A), both involving amino acids that bind the 3'-terminal UUU trinucleotide. All other Ala mutations were benign with respect to vegetative growth. Tests of 235 pairwise combinations of benign Lsm mutants identified six instances of inter-Lsm synthetic lethality and 45 cases of nonlethal synthetic growth defects. Thus, Lsm2-8 ring function is buffered by a network of internal genetic redundancies. A salient finding was that otherwise lethal single-gene deletions lsm2Δ, lsm3Δ, lsm4Δ, lsm5, and lsm8Δ were rescued by overexpression of U6 snRNA from a high-copy plasmid. Moreover, U6 overexpression rescued myriad lsmΔ lsmΔ double-deletions and lsmΔ lsmΔ lsmΔ triple-deletions. We find that U6 overexpression also rescues a lethal deletion of the U6 snRNP protein subunit Prp24 and that Prp24 overexpression bypasses the essentiality of the U6-associated Lsm subunits. Our results indicate that abetting U6 snRNA is the only essential function of the yeast Lsm2-8 proteins.
Collapse
Affiliation(s)
- Allen J Roth
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
| |
Collapse
|
8
|
Han L, Marcus E, D'Silva S, Phizicky EM. S. cerevisiae Trm140 has two recognition modes for 3-methylcytidine modification of the anticodon loop of tRNA substrates. RNA (NEW YORK, N.Y.) 2017; 23:406-419. [PMID: 28003514 PMCID: PMC5311504 DOI: 10.1261/rna.059667.116] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/12/2016] [Indexed: 05/25/2023]
Abstract
The 3-methylcytidine (m3C) modification is ubiquitous in eukaryotic tRNA, widely found at C32 in the anticodon loop of tRNAThr, tRNASer, and some tRNAArg species, as well as in the variable loop (V-loop) of certain tRNASer species. In the yeast Saccharomyces cerevisiae, formation of m3C32 requires Trm140 for six tRNA substrates, including three tRNAThr species and three tRNASer species, whereas in Schizosaccharomyces pombe, two Trm140 homologs are used, one for tRNAThr and one for tRNASer The occurrence of a single Trm140 homolog is conserved broadly among Ascomycota, whereas multiple Trm140-related homologs are found in metazoans and other fungi. We investigate here how S. cerevisiae Trm140 protein recognizes its six tRNA substrates. We show that Trm140 has two modes of tRNA substrate recognition. Trm140 recognizes G35-U36-t6A37 of the anticodon loop of tRNAThr substrates, and this sequence is an identity element because it can be used to direct m3C modification of tRNAPhe However, Trm140 recognition of tRNASer substrates is different, since their anticodons do not share G35-U36 and do not have any nucleotides in common. Rather, specificity of Trm140 for tRNASer is achieved by seryl-tRNA synthetase and the distinctive tRNASer V-loop, as well as by t6A37 and i6A37 We provide evidence that all of these components are important in vivo and that seryl-tRNA synthetase greatly stimulates m3C modification of tRNASer(CGA) and tRNASer(UGA) in vitro. In addition, our results show that Trm140 binding is a significant driving force for tRNA modification and suggest separate contributions from each recognition element for the modification.
Collapse
MESH Headings
- Anticodon/chemistry
- Anticodon/metabolism
- Base Sequence
- Binding Sites
- Cloning, Molecular
- Cytidine/analogs & derivatives
- Cytidine/genetics
- Cytidine/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression
- Microfilament Proteins/genetics
- Microfilament Proteins/metabolism
- Nucleic Acid Conformation
- Protein Binding
- Protein Biosynthesis
- Protein Domains
- RNA, Transfer, Phe/chemistry
- RNA, Transfer, Phe/genetics
- RNA, Transfer, Phe/metabolism
- RNA, Transfer, Ser/chemistry
- RNA, Transfer, Ser/genetics
- RNA, Transfer, Ser/metabolism
- RNA, Transfer, Thr/chemistry
- RNA, Transfer, Thr/genetics
- RNA, Transfer, Thr/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Substrate Specificity
- tRNA Methyltransferases/genetics
- tRNA Methyltransferases/metabolism
Collapse
Affiliation(s)
- Lu Han
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Sonia D'Silva
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Eric M Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| |
Collapse
|
9
|
Schwer B, Roth AJ, Shuman S. Will the circle be unbroken: specific mutations in the yeast Sm protein ring expose a requirement for assembly factor Brr1, a homolog of Gemin2. RNA (NEW YORK, N.Y.) 2017; 23:420-430. [PMID: 27974620 PMCID: PMC5311505 DOI: 10.1261/rna.059881.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/12/2016] [Indexed: 05/08/2023]
Abstract
A seven-subunit Sm protein ring assembles around specific U-rich RNA segments of the U1, U2, U4, and U5 snRNPs that direct pre-mRNA splicing. Using human snRNP crystal structures to guide mutagenesis in Saccharomyces cerevisiae, we gained new insights into structure-function relationships of the SmD1 and SmD2 subunits. Of 18 conserved amino acids comprising their RNA-binding sites or intersubunit interfaces, only Arg88 in SmD1 and Arg97 in SmD2 were essential for growth. Tests for genetic interactions with non-Sm splicing factors identified benign mutations of SmD1 (N37A, R88K, R93A) and SmD2 (R49A, N66A, R97K, D99A) that were synthetically lethal with null alleles of U2 snRNP subunits Lea1 and/or Msl1. Tests of 264 pairwise combinations of SmD1 and SmD2 alleles with each other and with a collection of SmG, SmE, SmF, SmB, and SmD3 alleles revealed 92 instances of inter-Sm synthetic lethality. We leveraged the Sm mutant collection to illuminate the function of the yeast Sm assembly factor Brr1 and its relationship to the metazoan Sm assembly factor Gemin2. Mutations in the adjacent SmE (K83A), SmF (K32A, F33A, R74K), SmD2 (R49A, N66A, E74A, R97K, D99A), and SmD1 (E18A, N37A) subunits-but none in the SmG, SmD3, and SmB subunits-were synthetically lethal with brr1Δ. Using complementation of brr1Δ lethality in two Sm mutant backgrounds as an in vivo assay of Brr1 activity, we identified as essential an N-terminal segment of Brr1 (amino acids 24-47) corresponding to the Gemin2 α1 helix that interacts with SmF and a Brr1 C-terminal peptide (336QKDLIE341) that, in Gemin2, interacts with SmD2.
Collapse
MESH Headings
- Amino Acid Sequence
- Binding Sites
- Gene Expression
- Genes, Lethal
- Genetic Complementation Test
- Humans
- Mutation
- Nerve Tissue Proteins/chemistry
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Protein Binding
- Protein Conformation, alpha-Helical
- Protein Conformation, beta-Strand
- Protein Interaction Domains and Motifs
- Protein Subunits/chemistry
- Protein Subunits/genetics
- Protein Subunits/metabolism
- RNA Splicing
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Ribonucleoproteins, Small Nuclear/chemistry
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Sequence Alignment
- Sequence Homology, Amino Acid
- Spliceosomes/genetics
- Spliceosomes/metabolism
Collapse
Affiliation(s)
- Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
| | - Allen J Roth
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| |
Collapse
|