1
|
Hou W, Yin S, Li P, Zhang L, Chen T, Qin D, Mustafa AU, Liu C, Song M, Qiu C, Xiong X, Wang J. Aberrant splicing of Ca V1.2 calcium channel induced by decreased Rbfox1 enhances arterial constriction during diabetic hyperglycemia. Cell Mol Life Sci 2024; 81:164. [PMID: 38575795 PMCID: PMC10995029 DOI: 10.1007/s00018-024-05198-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 02/23/2024] [Accepted: 03/04/2024] [Indexed: 04/06/2024]
Abstract
Diabetic hyperglycemia induces dysfunctions of arterial smooth muscle, leading to diabetic vascular complications. The CaV1.2 calcium channel is one primary pathway for Ca2+ influx, which initiates vasoconstriction. However, the long-term regulation mechanism(s) for vascular CaV1.2 functions under hyperglycemic condition remains unknown. Here, Sprague-Dawley rats fed with high-fat diet in combination with low dose streptozotocin and Goto-Kakizaki (GK) rats were used as diabetic models. Isolated mesenteric arteries (MAs) and vascular smooth muscle cells (VSMCs) from rat models were used to assess K+-induced arterial constriction and CaV1.2 channel functions using vascular myograph and whole-cell patch clamp, respectively. K+-induced vasoconstriction is persistently enhanced in the MAs from diabetic rats, and CaV1.2 alternative spliced exon 9* is increased, while exon 33 is decreased in rat diabetic arteries. Furthermore, CaV1.2 channels exhibit hyperpolarized current-voltage and activation curve in VSMCs from diabetic rats, which facilitates the channel function. Unexpectedly, the application of glycated serum (GS), mimicking advanced glycation end-products (AGEs), but not glucose, downregulates the expression of the splicing factor Rbfox1 in VSMCs. Moreover, GS application or Rbfox1 knockdown dynamically regulates alternative exons 9* and 33, leading to facilitated functions of CaV1.2 channels in VSMCs and MAs. Notably, GS increases K+-induced intracellular calcium concentration of VSMCs and the vasoconstriction of MAs. These results reveal that AGEs, not glucose, long-termly regulates CaV1.2 alternative splicing events by decreasing Rbfox1 expression, thereby enhancing channel functions and increasing vasoconstriction under diabetic hyperglycemia. This study identifies the specific molecular mechanism for enhanced vasoconstriction under hyperglycemia, providing a potential target for managing diabetic vascular complications.
Collapse
Affiliation(s)
- Wei Hou
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
- The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu, China
| | - Shumin Yin
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Pengpeng Li
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ludan Zhang
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tiange Chen
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Dongxia Qin
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Atta Ul Mustafa
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Caijie Liu
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Miaomiao Song
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Cheng Qiu
- Nanjing Comprehensive Stroke Center, Affiliated Nanjing Brain Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaoqing Xiong
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China.
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China.
- The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu, China.
| | - Juejin Wang
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, China.
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China.
- The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu, China.
| |
Collapse
|
2
|
Black CS, Whelan TA, Garside EL, MacMillan AM, Fast NM, Rader SD. Spliceosome assembly and regulation: insights from analysis of highly reduced spliceosomes. RNA (NEW YORK, N.Y.) 2023; 29:531-550. [PMID: 36737103 PMCID: PMC10158995 DOI: 10.1261/rna.079273.122] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 01/06/2023] [Indexed: 05/06/2023]
Abstract
Premessenger RNA splicing is catalyzed by the spliceosome, a multimegadalton RNA-protein complex that assembles in a highly regulated process on each intronic substrate. Most studies of splicing and spliceosomes have been carried out in human or S. cerevisiae model systems. There exists, however, a large diversity of spliceosomes, particularly in organisms with reduced genomes, that suggests a means of analyzing the essential elements of spliceosome assembly and regulation. In this review, we characterize changes in spliceosome composition across phyla, describing those that are most frequently observed and highlighting an analysis of the reduced spliceosome of the red alga Cyanidioschyzon merolae We used homology modeling to predict what effect splicing protein loss would have on the spliceosome, based on currently available cryo-EM structures. We observe strongly correlated loss of proteins that function in the same process, for example, in interacting with the U1 snRNP (which is absent in C. merolae), regulation of Brr2, or coupling transcription and splicing. Based on our observations, we predict splicing in C. merolae to be inefficient, inaccurate, and post-transcriptional, consistent with the apparent trend toward its elimination in this lineage. This work highlights the striking flexibility of the splicing pathway and the spliceosome when viewed in the context of eukaryotic diversity.
Collapse
Affiliation(s)
- Corbin S Black
- Department of Chemistry and Biochemistry, University of Northern British Columbia, Prince George, British Columbia, Canada V2N 4Z9
- Department of Anatomy and Cell Biology, McGill University, Montréal, Quebec, Canada H3A 0C7
| | - Thomas A Whelan
- Biodiversity Research Center and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Erin L Garside
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Andrew M MacMillan
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Naomi M Fast
- Biodiversity Research Center and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Stephen D Rader
- Department of Chemistry and Biochemistry, University of Northern British Columbia, Prince George, British Columbia, Canada V2N 4Z9
| |
Collapse
|
4
|
Xiao T, Li X, Felsenfeld G. The Myc-associated zinc finger protein (MAZ) works together with CTCF to control cohesin positioning and genome organization. Proc Natl Acad Sci U S A 2021; 118:e2023127118. [PMID: 33558242 PMCID: PMC7896315 DOI: 10.1073/pnas.2023127118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The Myc-associated zinc finger protein (MAZ) is often found at genomic binding sites adjacent to CTCF, a protein which affects large-scale genome organization through its interaction with cohesin. We show here that, like CTCF, MAZ physically interacts with a cohesin subunit and can arrest cohesin sliding independently of CTCF. It also shares with CTCF the ability to independently pause the elongating form of RNA polymerase II, and consequently affects RNA alternative splicing. CTCF/MAZ double sites are more effective at sequestering cohesin than sites occupied only by CTCF. Furthermore, depletion of CTCF results in preferential loss of CTCF from sites not occupied by MAZ. In an assay for insulation activity like that used for CTCF, binding of MAZ to sites between an enhancer and promoter results in down-regulation of reporter gene expression, supporting a role for MAZ as an insulator protein. Hi-C analysis of the effect of MAZ depletion on genome organization shows that local interactions within topologically associated domains (TADs) are disrupted, as well as contacts that establish the boundaries of individual TADs. We conclude that MAZ augments the action of CTCF in organizing the genome, but also shares properties with CTCF that allow it to act independently.
Collapse
Affiliation(s)
- Tiaojiang Xiao
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892-0540
| | - Xin Li
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892-0540
| | - Gary Felsenfeld
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892-0540
| |
Collapse
|
5
|
van der Feltz C, Nikolai B, Schneider C, Paulson JC, Fu X, Hoskins AA. Saccharomyces cerevisiae Ecm2 Modulates the Catalytic Steps of pre-mRNA Splicing. RNA (NEW YORK, N.Y.) 2021; 27:rna.077727.120. [PMID: 33547186 PMCID: PMC8051269 DOI: 10.1261/rna.077727.120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 02/03/2021] [Indexed: 05/10/2023]
Abstract
Genetic, biochemical, and structural studies have elucidated the molecular basis for spliceosome catalysis. Splicing is RNA catalyzed and the essential snRNA and protein factors are well-conserved. However, little is known about how non-essential components of the spliceosome contribute to the reaction and modulate the activities of the fundamental core machinery. Ecm2 is a non-essential yeast splicing factor that is a member of the Prp19-related complex of proteins. Cryo-electron microscopy (cryo-EM) structures have revealed that Ecm2 binds the U6 snRNA and is entangled with Cwc2, a factor previously found to promote a catalytically active conformation of the spliceosome. These structures also indicate that Ecm2 and the U2 snRNA likely form a transient interaction during 5' splice site (SS) cleavage. We have characterized genetic interactions between ECM2 and alleles of splicing factors that alter the catalytic steps in splicing. In addition, we have studied how loss of ECM2 impacts splicing of pre-mRNAs containing non-consensus or competing SS. Our results show that ECM2 functions during the catalytic stages of splicing. Our data are consistent with Ecm2 facilitating the formation and stabilization of the 1st-step catalytic site, promoting 2nd-step catalysis, and permiting alternate 5' SS usage. We propose that Cwc2 and Ecm2 can each fine-tune the spliceosome active site in unique ways. Their interaction network may act as a conduit through which splicing of certain pre-mRNAs, such as those containing weak or alternate splice sites, can be regulated.
Collapse
|
6
|
Chung CS, Tseng CK, Lai YH, Wang HF, Newman AJ, Cheng SC. Dynamic protein-RNA interactions in mediating splicing catalysis. Nucleic Acids Res 2019; 47:899-910. [PMID: 30395327 PMCID: PMC6344849 DOI: 10.1093/nar/gky1089] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/19/2018] [Indexed: 11/16/2022] Open
Abstract
The spliceosome is assembled via sequential interactions of pre-mRNA with five small nuclear RNAs and many proteins. Recent determination of cryo-EM structures for several spliceosomal complexes has provided deep insights into interactions between spliceosomal components and structural changes of the spliceosome between steps, but information on how the proteins interact with pre-mRNA to mediate the reaction is scarce. By systematic analysis of proteins interacting with the splice sites (SSs), we have identified many previously unknown interactions of spliceosomal components with the pre-mRNA. Prp8 directly binds over the 5′SS and the branch site (BS) for the first catalytic step, and the 5′SS and 3′SS for the second step. Switching the Prp8 interaction from the BS to the 3′SS requires Slu7, which interacts dynamically with pre-mRNA first, and then interacts stably with the 3′-exon after Prp16-mediated spliceosome remodeling. Our results suggest that Prp8 plays a key role in positioning the 5′SS and 3′SS, facilitated by Slu7 through interactions with Prp8 and substrate RNA to advance exon ligation. We also provide evidence that Prp16 first docks on the intron 3′ tail, then translocates in the 3′ to 5′ direction on remodeling the spliceosome.
Collapse
Affiliation(s)
- Che-Sheng Chung
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China
| | - Chi-Kang Tseng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China
| | - Yung-Hua Lai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China.,Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan 112, Republic of China
| | - Hui-Fang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China.,Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan 112, Republic of China
| | - Andrew J Newman
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Soo-Chen Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China
| |
Collapse
|
8
|
Galej WP, Toor N, Newman AJ, Nagai K. Molecular Mechanism and Evolution of Nuclear Pre-mRNA and Group II Intron Splicing: Insights from Cryo-Electron Microscopy Structures. Chem Rev 2018; 118:4156-4176. [PMID: 29377672 DOI: 10.1021/acs.chemrev.7b00499] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nuclear pre-mRNA splicing and group II intron self-splicing both proceed by two-step transesterification reactions via a lariat intron intermediate. Recently determined cryo-electron microscopy (cryo-EM) structures of catalytically active spliceosomes revealed the RNA-based catalytic core and showed how pre-mRNA substrates and reaction products are positioned in the active site. These findings highlight a strong structural similarity to the group II intron active site, strengthening the notion that group II introns and spliceosomes evolved from a common ancestor. Prp8, the largest and most conserved protein in the spliceosome, cradles the active site RNA. Prp8 and group II intron maturase have a similar domain architecture, suggesting that they also share a common evolutionary origin. The interactions between maturase and key group II intron RNA elements, such as the exon-binding loop and domains V and VI, are recapitulated in the interactions between Prp8 and key elements in the spliceosome's catalytic RNA core. Structural comparisons suggest that the extensive RNA scaffold of the group II intron was gradually replaced by proteins as the spliceosome evolved. A plausible model of spliceosome evolution is discussed.
Collapse
Affiliation(s)
- Wojciech P Galej
- EMBL Grenoble , 71 Avenue des Martyrs , 38042 Grenoble Cedex 09 , France
| | - Navtej Toor
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Andrew J Newman
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge CB2 0QH , U.K
| | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge CB2 0QH , U.K
| |
Collapse
|