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Virtanen L, Holm E, Halme M, West G, Lindholm F, Gullmets J, Irjala J, Heliö T, Padzik A, Meinander A, Eriksson JE, Taimen P. Lamin A/C phosphorylation at serine 22 is a conserved heat shock response to regulate nuclear adaptation during stress. J Cell Sci 2023; 136:289469. [PMID: 36695453 PMCID: PMC10022683 DOI: 10.1242/jcs.259788] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
The heat shock (HS) response is crucial for cell survival in harmful environments. Nuclear lamin A/C, encoded by the LMNA gene, contributes towards altered gene expression during HS, but the underlying mechanisms are poorly understood. Here, we show that upon HS, lamin A/C was reversibly phosphorylated at serine 22 in concert with HSF1 activation in human cells, mouse cells and Drosophila melanogaster in vivo. Consequently, the phosphorylation facilitated nucleoplasmic localization of lamin A/C and nuclear sphericity in response to HS. Interestingly, lamin A/C knock-out cells showed deformed nuclei after HS and were rescued by ectopic expression of wild-type lamin A, but not by a phosphomimetic (S22D) lamin A mutant. Furthermore, HS triggered concurrent downregulation of lamina-associated protein 2α (Lap2α, encoded by TMPO) in wild-type lamin A/C-expressing cells, but a similar response was perturbed in lamin A/C knock-out cells and in LMNA mutant patient fibroblasts, which showed impaired cell cycle arrest under HS and compromised survival at recovery. Taken together, our results suggest that the altered phosphorylation stoichiometry of lamin A/C provides an evolutionarily conserved mechanism to regulate lamina structure and serve nuclear adaptation and cell survival during HS.
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Affiliation(s)
- Laura Virtanen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Emilia Holm
- Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Mona Halme
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Gun West
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Fanny Lindholm
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Josef Gullmets
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland.,Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Juho Irjala
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Tiina Heliö
- Heart and Lung Center, Helsinki University Hospital and University of Helsinki, 00029 Helsinki, Finland
| | - Artur Padzik
- Genome Editing Core, Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Annika Meinander
- Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - John E Eriksson
- Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland.,Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Pekka Taimen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland.,Department of Pathology, Turku University Hospital, 20520 Turku, Finland
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Bártová E, Legartová S, Krejčí J, Řezníčková P, Kovaříková AS, Suchánková J, Fedr R, Smirnov E, Hornáček M, Raška I. Depletion of A-type lamins and Lap2α reduces 53BP1 accumulation at UV-induced DNA lesions and Lap2α protein is responsible for compactness of irradiated chromatin. J Cell Biochem 2018; 119:8146-8162. [PMID: 29923310 DOI: 10.1002/jcb.26770] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 02/02/2018] [Indexed: 12/29/2022]
Abstract
We studied how deficiency in lamins A/C and lamina-associated polypeptide 2α (Lap2α) affects DNA repair after irradiation. A-type lamins and Lap2α were not recruited to local DNA lesions and did not accumulate to γ-irradiation-induced foci (IRIF), as it is generally observed for well-known marker of DNA lesions, 53BP1 protein. At micro-irradiated chromatin of lmna double knockout (dn) and Lap2α dn cells, 53BP1 protein levels were reduced, compared to locally irradiated wild-type counterpart. Decreased levels of 53BP1 we also observed in whole populations of lmna dn and Lap2α dn cells, irradiated by UV light. We also studied distribution pattern of 53BP1 protein in a genome outside micro-irradiated region. In Lap2α deficient cells, identical fluorescence of mCherry-tagged 53BP1 protein was found at both microirradiated region and surrounding chromatin. However, a well-known marker of double strand breaks, γH2AX, was highly abundant in the lesion-surrounding genome of Lap2α deficient cells. Described changes, induced by irradiation in Lap2α dn cells, were not accompanied by cell cycle changes. In Lap2α dn cells, we additionally performed analysis by FLIM (Fluorescence Lifetime Imaging Microscopy) that showed different dynamic behavior of mCherry-tagged 53BP1 protein pools when it was compared with wild-type (wt) fibroblasts. This analysis revealed three different fractions of mCherry-53BP1 protein. Two of them showed identical exponential decay times (τ1 and τ3), but the decay rate of τ2 and amplitudes of fluorescence decays (A1-A3) were statistically different in wt and Lap2α dn fibroblasts. Moreover, γ-irradiation weakened an interaction between A-type lamins and Lap2α. Together, our results demonstrate how depletion of Lap2α affects DNA damage response (DDR) and how chromatin compactness is changed in Lap2α deficient cells exposed to radiation.
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Affiliation(s)
- Eva Bártová
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Soňa Legartová
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Jana Krejčí
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Petra Řezníčková
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | | | - Jana Suchánková
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Radek Fedr
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Evgeny Smirnov
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - Matúš Hornáček
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - Ivan Raška
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
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