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Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice

BACKGROUND AND AIMS: Recent technological advances have established vascular smooth muscle cells (SMCs) as central players in atherosclerosis. Increasingly complex genetic mouse models have unveiled that 30–70% of cells in experimentally induced atherosclerotic lesions derive from a handful of media...

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Detalles Bibliográficos
Autores principales: Steffensen, L.B., Stubbe, J., Overgaard, M., Larsen, J.H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9833216/
https://www.ncbi.nlm.nih.gov/pubmed/36644559
http://dx.doi.org/10.1016/j.athplu.2022.01.002
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author Steffensen, L.B.
Stubbe, J.
Overgaard, M.
Larsen, J.H.
author_facet Steffensen, L.B.
Stubbe, J.
Overgaard, M.
Larsen, J.H.
author_sort Steffensen, L.B.
collection PubMed
description BACKGROUND AND AIMS: Recent technological advances have established vascular smooth muscle cells (SMCs) as central players in atherosclerosis. Increasingly complex genetic mouse models have unveiled that 30–70% of cells in experimentally induced atherosclerotic lesions derive from a handful of medial SMCs, and that these can adopt a broad range of plaque cell phenotypes. Most of these models are based on the SMMHC-CreER(T2) mouse line as Cre-driver. Importantly, Cre-activation can be controlled in time (by administration of tamoxifen, TAM), which is critical to avoid unwanted effects of premature recombination events. The aim of this study was to scrutinize an unexpected observation of TAM-independent Cre-activity in this mouse line. METHODS: Cre-activity was assessed by PCR in tissues from SMMHC-CreER(T2) mice crossed with mice homozygous for loxP-flanked (floxed) exon 4 of Ccn2 (our gene-of-interest), and Ccn2 protein was measured in aortas by targeted mass spectrometry. RESULTS: We observed spontaneous near-complete excision of floxed Ccn2 in aortas from adult mice that were not treated with TAM. As a result, Ccn2 protein was significantly reduced in aortas from these mice, but not to the same extent as TAM-treated littermates. Remarkably, most of the excision was completed in 4-week-old mice. Excision was Cre-dependent, as knockout bands were negligible in heart and liver (dominated by non-SMCs) of these mice, and undetectable in the aorta in the absence of Cre. CONCLUSION: Our observations warrant caution, and we advocate inclusion of appropriate controls (i.e., TAM-untreated mice) in future studies.
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spelling pubmed-98332162023-01-12 Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice Steffensen, L.B. Stubbe, J. Overgaard, M. Larsen, J.H. Atheroscler Plus Short Communication BACKGROUND AND AIMS: Recent technological advances have established vascular smooth muscle cells (SMCs) as central players in atherosclerosis. Increasingly complex genetic mouse models have unveiled that 30–70% of cells in experimentally induced atherosclerotic lesions derive from a handful of medial SMCs, and that these can adopt a broad range of plaque cell phenotypes. Most of these models are based on the SMMHC-CreER(T2) mouse line as Cre-driver. Importantly, Cre-activation can be controlled in time (by administration of tamoxifen, TAM), which is critical to avoid unwanted effects of premature recombination events. The aim of this study was to scrutinize an unexpected observation of TAM-independent Cre-activity in this mouse line. METHODS: Cre-activity was assessed by PCR in tissues from SMMHC-CreER(T2) mice crossed with mice homozygous for loxP-flanked (floxed) exon 4 of Ccn2 (our gene-of-interest), and Ccn2 protein was measured in aortas by targeted mass spectrometry. RESULTS: We observed spontaneous near-complete excision of floxed Ccn2 in aortas from adult mice that were not treated with TAM. As a result, Ccn2 protein was significantly reduced in aortas from these mice, but not to the same extent as TAM-treated littermates. Remarkably, most of the excision was completed in 4-week-old mice. Excision was Cre-dependent, as knockout bands were negligible in heart and liver (dominated by non-SMCs) of these mice, and undetectable in the aorta in the absence of Cre. CONCLUSION: Our observations warrant caution, and we advocate inclusion of appropriate controls (i.e., TAM-untreated mice) in future studies. Elsevier 2022-01-31 /pmc/articles/PMC9833216/ /pubmed/36644559 http://dx.doi.org/10.1016/j.athplu.2022.01.002 Text en © 2022 The Author(s) https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Short Communication
Steffensen, L.B.
Stubbe, J.
Overgaard, M.
Larsen, J.H.
Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice
title Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice
title_full Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice
title_fullStr Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice
title_full_unstemmed Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice
title_short Tamoxifen-independent Cre-activity in SMMHC-CreER(T2) mice
title_sort tamoxifen-independent cre-activity in smmhc-creer(t2) mice
topic Short Communication
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9833216/
https://www.ncbi.nlm.nih.gov/pubmed/36644559
http://dx.doi.org/10.1016/j.athplu.2022.01.002
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