1
|
Víšková P, Ištvánková E, Ryneš J, Džatko Š, Loja T, Živković ML, Rigo R, El-Khoury R, Serrano-Chacón I, Damha MJ, González C, Mergny JL, Foldynová-Trantírková S, Trantírek L. In-cell NMR suggests that DNA i-motif levels are strongly depleted in living human cells. Nat Commun 2024; 15:1992. [PMID: 38443388 PMCID: PMC10914786 DOI: 10.1038/s41467-024-46221-y] [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: 09/10/2023] [Accepted: 02/13/2024] [Indexed: 03/07/2024] Open
Abstract
I-Motifs (iM) are non-canonical DNA structures potentially forming in the accessible, single-stranded, cytosine-rich genomic regions with regulatory roles. Chromatin, protein interactions, and intracellular properties seem to govern iM formation at sites with i-motif formation propensity (iMFPS) in human cells, yet their specific contributions remain unclear. Using in-cell NMR with oligonucleotide iMFPS models, we monitor iM-associated structural equilibria in asynchronous and cell cycle-synchronized HeLa cells at 37 °C. Our findings show that iMFPS displaying pHT < 7 under reference in vitro conditions occur predominantly in unfolded states in cells, while those with pHT > 7 appear as a mix of folded and unfolded states depending on the cell cycle phase. Comparing these results with previous data obtained using an iM-specific antibody (iMab) reveals that cell cycle-dependent iM formation has a dual origin, and iM formation concerns only a tiny fraction (possibly 1%) of genomic sites with iM formation propensity. We propose a comprehensive model aligning observations from iMab and in-cell NMR and enabling the identification of iMFPS capable of adopting iM structures under physiological conditions in living human cells. Our results suggest that many iMFPS may have biological roles linked to their unfolded states.
Collapse
Affiliation(s)
- Pavlína Víšková
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00, Brno, Czech Republic
| | - Eva Ištvánková
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00, Brno, Czech Republic
| | - Jan Ryneš
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
| | - Šimon Džatko
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- Centre for Advanced Materials Application, Slovak Academy of Sciences, 845 11, Bratislava, Slovakia
| | - Tomáš Loja
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
| | - Martina Lenarčič Živković
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- Slovenian NMR Centre, National Institute of Chemistry, SI-1000, Ljubljana, Slovenia
| | - Riccardo Rigo
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- Pharmaceutical and Pharmacological Sciences Department, University of Padova, 35131, Padova, Italy
| | - Roberto El-Khoury
- Department of Chemistry, McGill University, Montreal, QC, H3A0B8, Canada
| | - Israel Serrano-Chacón
- Instituto de Química Física 'Blas Cabrera', CSIC, C/Serrano 119, 28006, Madrid, Spain
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, QC, H3A0B8, Canada
| | - Carlos González
- Instituto de Química Física 'Blas Cabrera', CSIC, C/Serrano 119, 28006, Madrid, Spain
| | - Jean-Louis Mergny
- Institute of Biophysics, Czech Academy of Sciences, Brno, 612 00, Czech Republic
- Laboratoire d'Optique & Biosciences, Institut Polytechnique de Paris, Inserm, CNRS, Ecole Polytechnique, Palaiseau, 91120, France
| | - Silvie Foldynová-Trantírková
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic.
- Institute of Biophysics, Czech Academy of Sciences, Brno, 612 00, Czech Republic.
| | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic.
| |
Collapse
|
2
|
Abstract
Western blotting (WB), also known as immunoblotting, is a well-known molecular biology method that biologists often use to investigate many features of the protein, ranging from basic protein analysis to disease detection. WB is simple, unique, rapid, widely used routine tool with easy interpretation and definite results. It is being used in various fields of science, research and development, diagnostic labs and hospitals. The principle of WB is to accomplish the separation of proteins based on molecular weight and charge. This review addresses in detail the individual steps involved in the WB technique, its troubleshooting, internal loading controls, total protein staining and its diverse applications in scientific research and clinical settings, along with its future perspectives.
Collapse
|
3
|
Watanabe N, Nakano M, Mitsuishi Y, Hara N, Mano T, Iwata A, Murayama S, Suzuki T, Ikeuchi T, Nishimura M. Transcriptional downregulation of FAM3C/ILEI in the Alzheimer's brain. Hum Mol Genet 2021; 31:122-132. [PMID: 34378027 DOI: 10.1093/hmg/ddab226] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/29/2021] [Accepted: 08/02/2021] [Indexed: 11/14/2022] Open
Abstract
Amyloid-β (Aβ) accumulation in the brain triggers the pathogenic cascade for Alzheimer's disease (AD) development. The secretory protein FAM3C (also named ILEI) is a candidate for an endogenous suppressor of Aβ production. In this study, we found that FAM3C expression was transcriptionally downregulated in the AD brain. To determine the transcriptional mechanism of the human FAM3C gene, we delineated the minimal 5'-flanking sequence required for basal promoter activity. From a database search for DNA-binding motifs, expression analysis using cultured cells, and promoter DNA-binding assays, we identified SP1 and EBF1 as candidate basal transcription factors for FAM3C, and found that SMAD1 was a putative inducible transcription factor and KLF6 was a transcription repressor for FAM3C. Genomic deletion of the basal promoter sequence from HEK293 and Neuro-2a cells markedly reduced endogenous expression of FAM3C and abrogated SP1- or EBF1-mediated induction of FAM3C. Nuclear protein extracts from AD brains contained lower levels of SP1 and EBF1 than did those from control brains, although the relative mRNA levels of these factors did not differ significantly between the groups. Additionally, the ability of nuclear SP1 and EBF1 in AD brains to bind with the basal promoter sequence-containing DNA probe was reduced compared with the binding ability of these factors in control brains. Thus, the transcriptional downregulation of FAM3C in the AD brain is attributable to the reduced nuclear levels and genomic DNA binding of SP1 and EBF1. An expressional decline in FAM3C may be a risk factor for Aβ accumulation and eventually AD development.
Collapse
Affiliation(s)
- Naoki Watanabe
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga 520-2192, Japan
| | - Masaki Nakano
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga 520-2192, Japan
| | - Yachiyo Mitsuishi
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga 520-2192, Japan
| | - Norikazu Hara
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Tatsuo Mano
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Atsushi Iwata
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.,Department of Neuropathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan
| | - Shigeo Murayama
- Department of Neuropathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan
| | - Toshiharu Suzuki
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Hokkaido 060-0812, Japan
| | - Takeshi Ikeuchi
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Masaki Nishimura
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga 520-2192, Japan
| |
Collapse
|
4
|
Gel-Based Analysis of Protein-Nucleic Acid Interactions. Methods Mol Biol 2021; 2263:321-339. [PMID: 33877605 PMCID: PMC7614308 DOI: 10.1007/978-1-0716-1197-5_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Electrophoretic mobility shift assays (EMSAs) are among the most frequently used and straightforward experiments for studying protein-nucleic acid interactions. EMSAs rely on the principle that protein-nucleic acid complexes have reduced electrophoretic mobility in a native gel matrix compared to free nucleic acid due to their larger size and reduced negative charge. Therefore, bands for the protein-nucleic acid complexes are shifted in a gel and can be distinguished from free nucleic acids. EMSAs remain a popular technique since they do not require specialist equipment and the complexes formed are easily visualized. Furthermore, the technique can be adapted to enable various aspects of protein-nucleic acid interactions to be investigated, including sequence specificity, estimated binding affinity, and binding stoichiometry.
Collapse
|