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Mutations in the PCNA-binding site of CDKN1C inhibit cell proliferation by impairing the entry into S phase.

Borges KS, Arboleda VA, Vilain E - Cell Div (2015)

Bottom Line: Mutations in the PCNA-binding site of CDKN1C significantly increase CDKN1C protein stability and prevent cell cycle progression into the S phase.However, the IMAGe-mutant CDKN1C protein decreased cell growth significantly more than both the wild-type or BWS protein.These findings bring new insights into the molecular events underlying IMAGe syndrome.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, 695 Charles E. Young Drive, Los Angeles, CA 90095 USA ; Department of Genetics, Ribeirão Preto Medical School, University of São, Ribeirão Preto, Av. Bandeirantes 3900, CEP 14049-900 Ribeirão Preto, SP Brazil.

ABSTRACT
CDKN1C (also known as P57 (kip2) ) is a cyclin-dependent kinase inhibitor that functions as a negative regulator of cell proliferation through G1 phase cell cycle arrest. Recently, our group described gain-of-function mutations in the PCNA-binding site of CDKN1C that result in an undergrowth syndrome called IMAGe Syndrome (Intrauterine Growth Restriction, Metaphyseal dysplasia, Adrenal hypoplasia, and Genital anomalies), with life-threatening consequences. Loss-of-function mutations in CDKN1C have been identified in 5-10% of individuals with Beckwith-Wiedemann syndrome (BWS), an overgrowth disorder with features that are the opposite of IMAGe syndrome. Here, we investigate the effects of IMAGe-associated mutations on protein stability, cell cycle progression and cell proliferation. Mutations in the PCNA-binding site of CDKN1C significantly increase CDKN1C protein stability and prevent cell cycle progression into the S phase. Overexpression of either wild-type or BWS-mutant CDKN1C inhibited cell proliferation. However, the IMAGe-mutant CDKN1C protein decreased cell growth significantly more than both the wild-type or BWS protein. These findings bring new insights into the molecular events underlying IMAGe syndrome.

No MeSH data available.


Related in: MedlinePlus

IMAGe-mutants have decreased progression through S-phase after synchronization in S-phase. (A) Cell cycle analyses by flow cytometry of cells at T0 transfected as described in Figure 2A. (B) Immunoblot analysis of transfected cells showed a failure of accumulation of Cyclin-A, an S phase marker in IMAGe-mutant transfected cells at time T0.
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Fig3: IMAGe-mutants have decreased progression through S-phase after synchronization in S-phase. (A) Cell cycle analyses by flow cytometry of cells at T0 transfected as described in Figure 2A. (B) Immunoblot analysis of transfected cells showed a failure of accumulation of Cyclin-A, an S phase marker in IMAGe-mutant transfected cells at time T0.

Mentions: To further investigate this, we examined cell cycle phase distribution of the cells at time T0. The percentage of the cells in the G1 phase was increased by the transfection of wild-type CDKN1C compared with empty plasmid and BWS-mutant (32.31%, 14.88% and 19.85% respectively). However, cells transfected with IMAGe-mutant CDKN1C had the highest percentage of cells in the G1 phase (36.94%) and the lowest proportion of cells in the S-phase (40.06%) (Figure 3A).Figure 3


Mutations in the PCNA-binding site of CDKN1C inhibit cell proliferation by impairing the entry into S phase.

Borges KS, Arboleda VA, Vilain E - Cell Div (2015)

IMAGe-mutants have decreased progression through S-phase after synchronization in S-phase. (A) Cell cycle analyses by flow cytometry of cells at T0 transfected as described in Figure 2A. (B) Immunoblot analysis of transfected cells showed a failure of accumulation of Cyclin-A, an S phase marker in IMAGe-mutant transfected cells at time T0.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389716&req=5

Fig3: IMAGe-mutants have decreased progression through S-phase after synchronization in S-phase. (A) Cell cycle analyses by flow cytometry of cells at T0 transfected as described in Figure 2A. (B) Immunoblot analysis of transfected cells showed a failure of accumulation of Cyclin-A, an S phase marker in IMAGe-mutant transfected cells at time T0.
Mentions: To further investigate this, we examined cell cycle phase distribution of the cells at time T0. The percentage of the cells in the G1 phase was increased by the transfection of wild-type CDKN1C compared with empty plasmid and BWS-mutant (32.31%, 14.88% and 19.85% respectively). However, cells transfected with IMAGe-mutant CDKN1C had the highest percentage of cells in the G1 phase (36.94%) and the lowest proportion of cells in the S-phase (40.06%) (Figure 3A).Figure 3

Bottom Line: Mutations in the PCNA-binding site of CDKN1C significantly increase CDKN1C protein stability and prevent cell cycle progression into the S phase.However, the IMAGe-mutant CDKN1C protein decreased cell growth significantly more than both the wild-type or BWS protein.These findings bring new insights into the molecular events underlying IMAGe syndrome.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, 695 Charles E. Young Drive, Los Angeles, CA 90095 USA ; Department of Genetics, Ribeirão Preto Medical School, University of São, Ribeirão Preto, Av. Bandeirantes 3900, CEP 14049-900 Ribeirão Preto, SP Brazil.

ABSTRACT
CDKN1C (also known as P57 (kip2) ) is a cyclin-dependent kinase inhibitor that functions as a negative regulator of cell proliferation through G1 phase cell cycle arrest. Recently, our group described gain-of-function mutations in the PCNA-binding site of CDKN1C that result in an undergrowth syndrome called IMAGe Syndrome (Intrauterine Growth Restriction, Metaphyseal dysplasia, Adrenal hypoplasia, and Genital anomalies), with life-threatening consequences. Loss-of-function mutations in CDKN1C have been identified in 5-10% of individuals with Beckwith-Wiedemann syndrome (BWS), an overgrowth disorder with features that are the opposite of IMAGe syndrome. Here, we investigate the effects of IMAGe-associated mutations on protein stability, cell cycle progression and cell proliferation. Mutations in the PCNA-binding site of CDKN1C significantly increase CDKN1C protein stability and prevent cell cycle progression into the S phase. Overexpression of either wild-type or BWS-mutant CDKN1C inhibited cell proliferation. However, the IMAGe-mutant CDKN1C protein decreased cell growth significantly more than both the wild-type or BWS protein. These findings bring new insights into the molecular events underlying IMAGe syndrome.

No MeSH data available.


Related in: MedlinePlus