Dataset Information

Headcase and Unkempt Regulate Tissue Growth and Cell Cycle Progression in Response to Nutrient Restriction.

ABSTRACT: Nutrient restriction (NR) decreases the incidence and growth of many types of tumors, yet the underlying mechanisms are not fully understood. In this study, we identified Headcase (Hdc) and Unkempt (Unk) as two NR-specific tumor suppressor proteins that form a complex to restrict cell cycle progression and tissue growth in response to NR in Drosophila. Loss of Hdc or Unk does not confer apparent growth advantage under normal nutrient conditions but leads to accelerated cell cycle progression and tissue overgrowth under NR. Hdc and Unk bind to the TORC1 component Raptor and preferentially regulate S6 phosphorylation in a TORC1-dependent manner. We further show that HECA and UNK, the human counterparts of Drosophila Hdc and Unk, respectively, have a conserved function in regulating S6 phosphorylation and tissue growth. The identification of Hdc and Unk as two NR-specific tumor suppressors provides insight into molecular mechanisms underlying the anti-tumorigenic effects of NR.

SUBMITTER: Li N

PROVIDER: S-EPMC6350942 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Headcase and Unkempt Regulate Tissue Growth and Cell Cycle Progression in Response to Nutrient Restriction.

Li Naren N Liu Qinfang Q Xiong Yulan Y Yu Jianzhong J

Cell reports 20190101 3

Nutrient restriction (NR) decreases the incidence and growth of many types of tumors, yet the underlying mechanisms are not fully understood. In this study, we identified Headcase (Hdc) and Unkempt (Unk) as two NR-specific tumor suppressor proteins that form a complex to restrict cell cycle progression and tissue growth in response to NR in Drosophila. Loss of Hdc or Unk does not confer apparent growth advantage under normal nutrient conditions but leads to accelerated cell cycle progression and ...[more]

PMID: 30650363

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Project description:The activity of Cdc2 (CDK1) kinase, which coordinates cell cycle progression and DNA break repair, is blocked upon its phosphorylation at tyrosine 15 (Y15) by Wee1 kinase in the presence of DNA damage. How Cdc2 can support DNA repair whilst being inactivated by the DNA damage checkpoint remains to be explained. Human CDK1 is phosphorylated by Myt1 kinase at threonine 14 (T14) close to its ATP binding site before being modified at threonine 161 (T167Sp) in its T-loop by the CDK-activating kinase (CAK). While modification of T161 promotes association with the cyclin partner, phosphorylation of T14 inhibits the CDK1-cyclin complex. This inhibition is further enforced by the modification of Y15 by Wee1 in the presence of DNA lesions. In S.pombe, the dominant inhibition of Cdc2 is provided by the phosphorylation of Y15 and only a small amount of Cdc2 is modified at T14 when cells are in S phase. Unlike human cells, both inhibitory modifications are executed by Wee1. Using the novel IEFPT technology, which combines isoelectric focusing (IEF) with Phos-tag SDS electrophoresis (PT), we report here that S.pombe Cdc2 kinase exists in seven forms. While five forms are phosphorylated, two species are not. Four phospho-forms associate with cyclin B (Cdc13) of which only two are modified at Y15 by Wee1. Interestingly, only one Y15-modified species carries also the T14 modification. The fifth phospho-form has a low affinity for cyclin B and is neither Y15 nor T14 modified. The two unphosphorylated forms may contribute directly to the DNA damage response as only they associate with the DNA damage checkpoint kinase Chk1. Interestingly, cyclin B is also present in the unphosphorylated pool. We also show that the G146D mutation in Cdc2.1w, which renders Cdc2 insensitive to Wee1 inhibition, is aberrantly modified in a Wee1-dependent manner. In conclusion, our work adds support to the idea that two distinct Cdc2 pools regulate cell cycle progression and the response to DNA damage.

Dataset Information

Headcase and Unkempt Regulate Tissue Growth and Cell Cycle Progression in Response to Nutrient Restriction.

Publications

Headcase and Unkempt Regulate Tissue Growth and Cell Cycle Progression in Response to Nutrient Restriction.

Similar Datasets

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