Editing Cell cycle (section)

== Fluorescence imaging of the cell cycle ==
[[File:Far-Red & Near-infrared Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI).gif|thumb|200px|Fluorescent proteins visualize the cell cycle progression. IFP2.0-hGem(1/110) fluorescence is shown in green and highlights the S/G<sub>2</sub>/M phases. [[smURFP]]-hCdtI(30/120) fluorescence is shown in red and highlights the G<sub>0</sub>/G<sub>1</sub> phases.]]
Pioneering work by Atsushi Miyawaki and coworkers developed the fluorescent ubiquitination-based cell cycle indicator ([http://www.conncoll.edu/ccacad/zimmer/GFP-ww/cooluses19.html FUCCI]), which enables [[fluorescence]] imaging of the cell cycle. Originally, a [[green fluorescent protein]], mAG, was fused to hGem(1/110) and an orange [[fluorescent protein]] (mKO<sub>2</sub>) was fused to hCdt1(30/120). Note, these fusions are fragments that contain a [[Nuclear Localization Signal|nuclear localization signal]] and [[ubiquitination]] sites for [[Protein degradation|degradation]], but are not functional proteins. The [[green fluorescent protein]] is made during the S, G<sub>2</sub>, or M phase and degraded during the G<sub>0</sub> or G<sub>1</sub> phase, while the orange [[fluorescent protein]] is made during the G<sub>0</sub> or G<sub>1</sub> phase and destroyed during the S, G<sub>2</sub>, or M phase.<ref>{{cite journal | vauthors = Sakaue-Sawano A, Kurokawa H, Morimura T, Hanyu A, Hama H, Osawa H, Kashiwagi S, Fukami K, Miyata T, Miyoshi H, Imamura T, Ogawa M, Masai H, Miyawaki A | display-authors = 6 | title = Visualizing spatiotemporal dynamics of multicellular cell-cycle progression | journal = Cell | volume = 132 | issue = 3 | pages = 487–498 | date = February 2008 | pmid = 18267078 | doi = 10.1016/j.cell.2007.12.033 | s2cid = 15704902 | doi-access = free }}</ref> A far-red and near-infrared FUCCI was developed using a [[cyanobacteria]]-derived [[fluorescent protein]] ([[smURFP]]) and a [[Phytochrome|bacteriophytochrome]]-derived [[fluorescent protein]] ([http://www.nature.com/nmeth/journal/vaop/ncurrent/fig_tab/nmeth.3935_SV2.html movie found at this link]).<ref>{{cite journal | vauthors = Rodriguez EA, Tran GN, Gross LA, Crisp JL, Shu X, Lin JY, Tsien RY | title = A far-red fluorescent protein evolved from a cyanobacterial phycobiliprotein | journal = Nature Methods | volume = 13 | issue = 9 | pages = 763–769 | date = September 2016 | pmid = 27479328 | pmc = 5007177 | doi = 10.1038/nmeth.3935 }}</ref>
Several modifications have been made to the original FUCCI system to improve its usability in several in vitro systems and model organisms. These advancements have increased the sensitivity and accuracy of cell cycle phase detection, enabling more precise assessments of cellular proliferation<ref>{{cite journal | vauthors = Salmenov R, Mummery C, ter Huurne M | title= Cell cycle visualization tools to study cardiomyocyte proliferation in real-time| journal = Open Biology| volume = 14 | issue = 10 | pages = 240167 | date = October 2024 | pmid = 39378987| doi = 10.1098/rsob.240167 | pmc = 11461051 }}
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