| November
Editor-in-Chief | Qi
D-type cyclin is a central regulator of the cell division cycle Research on the regulatory mechanism of [2, 3] is still controversial.
Recently, the Michele Pagano research group of New York University Grossman School of Medicine and the University of Pennsylvania Perelman School of Medicine Luca Busino research group jointly published an article entitled CRL4AMBRA1 is a master regulator of D-type cyclins, Stanford University Julien Sage研究组发表题为The AMBRA1 E3 ligase adaptor regulates the stability of cyclin D的文章，以及丹麦癌症协会研究中心Francesco Cecconi研究组、意大利班比诺中心Gesù儿童医院Jiri Bartek研究组合作发表题为AMBRA1 regulates cyclin D to guard S-phase entry and genomic integrityThe three articles published back-to-back in Nature unravel the final answer to this controversy, finds the key regulator of D-type cyclin.
D-type cyclins, including cyclinD1, cyclinD2 and cyclinD3, promote cell division by activating CDK4 and CDK6, thereby phosphorylating and losing [1], the protein of the RB family. To date, seven substrate receptors in the CUL1-RING ubiquitin ligase complex, FBXO4, FBXO31, β-TrCP, FBXW8, SKP2, FBXL2, FBXL8, and the APC/C complex (Anaphase-promoting complex/cyclosome) It was once thought to be the factor [3] that targets D-type cyclin for degradation of . However, previous studies have shown that deletion of one or several factors in the CUL1-RING ubiquitin ligase complex or knockdown of the APC/C complex activity in cells does not affect the stability of cyclinD1 [2]. This result suggests that there must be one or more other ubiquitin ligases in the cell that target D-type cyclins.
In order to find the key regulators of D-type cyclin turnover, the authors conducted three different ways of screening (Figure 1) . First, the authors found that cyclinD1 and cyclinD3 protein levels, as well as -phosphorylated -modified proteins, were stably accumulated after treatment of cells with the inhibitor , which targets the CUL1-RING ubiquitin ligase complex, which was consistent with previous studies. studies are consistent. Subsequently, the authors used short-interfering RNA to stably express fluorescently labeled cyclinD1, and targeted DCAFs (DDB1-CUL4-associated factors) by transfecting oligonucleotide . By this method, identified and obtained five targets .Among them, four targets ((AMBRA1, DDA1, ERCC8, TOR1AIP2) were found in the second step of the two cell line screening experiments and the wild protein group were screened by the authors. Type cyclinD1 interacts with , but does not interact with cyclinD1 mutants that are insensitive to ubiquitin -mediated degradation.Among them, only AMBRA1 does indeed interact with the substrate through ubiquitin ligase binding cyclinD1 interacts because their interactions are not affected by proteasome inhibitors such as MG132.Finally, the authors performed a genome-wide CRISPR-Cas9 screen and found two that may serve as substrates The authors found that AMBRA1 was the only factor present in all three screens.
Figure 1. Three screening protocols for D-type cyclin regulators identify the regulator of cyclinD1 as AMBRA1
Subsequent authors We found that AMBRA1 does target the D-type cyclin cyclinD1 for degradation. Knockdown of AMBRA1 but not other ubiquitinated ligases induces the accumulation and stabilization of endogenous cyclinD1 as well as cyclinD3. Using the auxin -induced degradation subsystem [4], the authors further demonstrated that endogenous degradation of AMBRA1 in cells induces the accumulation of cyclinD1.
is similar to other substrate receptors as tumor suppressors, AMBRA1 shows the signature of cancer-related mutations, which suggests that AMBRA1 may be an tumor suppressor gene [5]. By analyzing The Cancer Genome Atlas (The Cancer Genome Atlas) database, the authors found that low AMBRA1 levels indeed have a strong correlation with poor prognosis in various tumors. Furthermore, the authors found that deletion of AMBRA1 reduced cell sensitivity to CDK4/6 inhibitors. In AMBRA1 knockout mice , the interaction between D-type cyclin and CDK4 is significantly increased. Then the authors carried out tumor transplantation experiments with control group and AMBRA1 knockout diffuse large B-cell lymphoma cells, and treated mice with Palbociclib (palbociclib, CDK4/6 kinase inhibitor) , the authors found that AMBRA1 knockout-derived tumors were significantly reduced, and the effect of high-concentration Palbociclib treatment was more pronounced.
Overall, 's work has discovered and conjointly identified AMBRA1, a key regulator of D-type cyclins, and found that AMBRA1 is found in normal cells, cancer cells, and developing mouse embryos. Deletion results in increased levels of D-type cyclin (Figure 2) . This resulted in increased levels of RB1 phosphorylation and an increase in the ability of cells to proliferate compared to cells with normal amounts of AMBRA1.In addition, the authors found that AMBRA1 knockdown increased the level of the transcription factor protein N-MYC, a family of MYC proteins that upregulates D- and E-type cyclins, thereby accelerating cell cycle progression. These studies suggest that AMBRA1 is a tumor suppressor protein that may function as a key target for tumor therapy in the future.
Figure 2. Working model
These three works found the key regulators of D-type cyclins back-to-back, and the corresponding opinion article Path to destruction for a cell-division regulator was distributed, and the work was highly appraised , and this mechanism may be responsible for the lack of response of some human tumors to inhibitor therapy.Written by | November Editor-in-Chief | Qi D-type cyclin is a central regulator of the cell division cycle Research on the regulatory mechanism of [2, 3] is still controversial. Recently, the Michele Pagano research group of New York University Grossman School of Medicine and the University of Pennsylvania Perelman School of Medicine Luca Busino research group jointly published an article entitled CRL4AMBRA1 is a master regulator of D-type cyclins, Stanford University Julien Sage研究组发表题为The AMBRA1 E3 ligase adaptor regulates the stability of cyclin D的文章，以及丹麦癌症协会研究中心Francesco Cecconi研究组、意大利班比诺中心Gesù儿童医院Jiri Bartek研究组合作发表题为AMBRA1 regulates cyclin D to guard S-phase entry and genomic integrityThe three articles published back-to-back in Nature unravel the final answer to this controversy, finds the key regulator of D-type cyclin. D-type cyclins include cyclinD1, cyclinD2 and cyclinD3, which promote cell division by activating CDK4 and CDK6,Furthermore, the protein of the RB family is phosphorylated and depleted [1]. To date, seven substrate receptors in the CUL1-RING ubiquitin ligase complex, FBXO4, FBXO31, β-TrCP, FBXW8, SKP2, FBXL2, FBXL8, and the APC/C complex (Anaphase-promoting complex/cyclosome) It was once thought to be the factor [3] that targets D-type cyclin for degradation of . However, previous studies have shown that deletion of one or several factors in the CUL1-RING ubiquitin ligase complex or knockdown of the APC/C complex activity in cells does not affect the stability of cyclinD1 [2]. This result suggests that there must be one or more other ubiquitin ligases in the cell that target D-type cyclins. In order to find the key regulators of D-type cyclin turnover, the authors conducted three different ways of screening (Figure 1) . First, the authors found that cyclinD1 and cyclinD3 protein levels, as well as -phosphorylated -modified proteins, were stably accumulated after treatment of cells with the inhibitor , which targets the CUL1-RING ubiquitin ligase complex, which was consistent with previous studies. studies are consistent. Subsequently, the authors used short-interfering RNA to stably express fluorescently labeled cyclinD1, and targeted DCAFs (DDB1-CUL4-associated factors) by transfecting oligonucleotide . By this method, identified and obtained five targets . Among them, four targets ((AMBRA1, DDA1, ERCC8, TOR1AIP2) were screened in the second step of the two cell line screening experiments.The authors identified six s that interacted with wild-type cyclinD1 by means of proteome , but no interaction with cyclinD1 mutants that were insensitive to ubiquitin -mediated degradation. Among them, only AMBRA1 does interact with cyclinD1 through the binding between ubiquitin ligase and substrate, because their interaction is not affected by proteasome inhibitors such as MG132. Finally, the authors performed a genome-wide CRISPR-Cas9 screen, which identified two proteins that may act as substrate receptors. The authors found that AMBRA1 was the only factor present in all three screens. Figure 1. Three screening protocols for D-type cyclin regulators identify the regulator of cyclinD1 as AMBRA1 The authors then found that AMBRA1 does target D-type cyclin cyclinD1 for degradation. Knockdown of AMBRA1, but not other ubiquitinated ligases, induced the accumulation and stabilization of endogenous cyclinD1 and cyclinD3. Using the auxin -induced degradation subsystem [4], the authors further demonstrated that endogenous degradation of AMBRA1 in cells induces the accumulation of cyclinD1. Similar to other substrate receptors that act as tumor suppressors, AMBRA1 displays characteristics of cancer-associated mutations,This indicates that AMBRA1 may be an tumor suppressor gene [5]. By analyzing The Cancer Genome Atlas (The Cancer Genome Atlas) database, the authors found that low AMBRA1 levels indeed have a strong correlation with poor prognosis in various tumors. Furthermore, the authors found that deletion of AMBRA1 reduced cell sensitivity to CDK4/6 inhibitors. In AMBRA1 knockout mice , the interaction between D-type cyclin and CDK4 is significantly increased. Then the authors carried out tumor transplantation experiments with control group and AMBRA1 knockout diffuse large B-cell lymphoma cells, and treated mice with Palbociclib (palbociclib, CDK4/6 kinase inhibitor) , the authors found that AMBRA1 knockout-derived tumors were significantly reduced, and the effect of high-concentration Palbociclib treatment was more pronounced. Overall, 's work has discovered and conjointly identified AMBRA1, a key regulator of D-type cyclins, and found that AMBRA1 is found in normal cells, cancer cells, and developing mouse embryos. Deletion results in increased levels of D-type cyclin (Figure 2) . This resulted in increased levels of RB1 phosphorylation and an increase in the ability of cells to proliferate compared to cells with normal amounts of AMBRA1. In addition, the authors found that AMBRA1 knockdown increased the level of the transcription factor protein N-MYC, a family of MYC proteins that upregulates D- and E-type cyclins, thereby accelerating cell cycle progression. These studies show that AMBRA1 is a tumor suppressor protein,It may play a role as a key target for tumor therapy in the future. Figure 2. Working model These three works found the key regulators of D-type cyclins back-to-back, and the corresponding opinion article Path to destruction for a cell-division regulator was distributed, and the work was highly appraised ,This mechanism may be the reason why some human tumors lack response to inhibitor therapy. 原文链接： https://doi.org/10.1038/s41586-021-03445-y https://doi.org/10.1038/s41586-021-03474-7 https://doi.org/10.1038/s41586-021- 03422-5 制版人：十一 参考文献 . Malumbres, M. & Barbacid, M. Cell cycle, CDKs and cancer: a changing paradigm.
. Kanie, T. et al. Genetic reevaluation of the role of F-box proteins in cyclin D1 degradation. Molecular and cellular biology 32, 590-605, doi:10.1128/mcb.06570-11 (2012).
. Qie, S. & Diehl, J. A. Cyclin D degradation by E3 ligases in cancer progression and treatment. Seminars in cancer biology 67 , 159-170, doi:10.1016/j.semcancer.2020.01.012 (2020).
4. Natsume, T., Kiyomitsu, T., Saga, Y. & Kanemaki, M. T. Rapid Protein Depletion in Human Cells by Auxin-Inducible Degron Tagging with Short Homology Donors. Cell reports 15, 210-218, doi:10.1016/j.celrep.2016.03.001 (2016).
5. Davoli, T. et al. Cumulative haploinsufficiency and triplosensitivity drive aneuploidy patterns and shape the cancer genome.Personal forwarding and sharing are welcome. Reprinting is prohibited without permission. The copyright of all published works is owned by BioArt. BioArt reserves all legal rights and violators will be held accountable.
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