Novel Insights into the INK4-CDK4/6-Rb Pathway:  Counter Action of Gankyrin against INK4 Proteins Regulates the CDK4-Mediated Phosphorylation of Rb†

Biochemistry ◽  
2002 ◽  
Vol 41 (12) ◽  
pp. 3977-3983 ◽  
Author(s):  
Junan Li ◽  
Ming-Daw Tsai
Keyword(s):  
Rb Pathway ◽  
Ink4 Proteins

scholarly journals Global phosphoproteomics reveals DYRK1A regulates CDK1 activity in glioblastoma cells

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ariadna Recasens ◽  
Sean J. Humphrey ◽  
Michael Ellis ◽  
Monira Hoque ◽  
Ramzi H. Abbassi ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Cyclin B ◽  
Anaphase Promoting Complex ◽  
Mechanistic Studies ◽  
Glioblastoma Cells ◽  
Cycle Arrest ◽  
Dual Specificity ◽  
Rb Pathway ◽  
High Doses

AbstractBoth tumour suppressive and oncogenic functions have been reported for dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A). Herein, we performed a detailed investigation to delineate the role of DYRK1A in glioblastoma. Our phosphoproteomic and mechanistic studies show that DYRK1A induces degradation of cyclin B by phosphorylating CDC23, which is necessary for the function of the anaphase-promoting complex, a ubiquitin ligase that degrades mitotic proteins. DYRK1A inhibition leads to the accumulation of cyclin B and activation of CDK1. Importantly, we established that the phenotypic response of glioblastoma cells to DYRK1A inhibition depends on both retinoblastoma (RB) expression and the degree of residual DYRK1A activity. Moderate DYRK1A inhibition leads to moderate cyclin B accumulation, CDK1 activation and increased proliferation in RB-deficient cells. In RB-proficient cells, cyclin B/CDK1 activation in response to DYRK1A inhibition is neutralized by the RB pathway, resulting in an unchanged proliferation rate. In contrast, complete DYRK1A inhibition with high doses of inhibitors results in massive cyclin B accumulation, saturation of CDK1 activity and cell cycle arrest, regardless of RB status. These findings provide new insights into the complexity of context-dependent DYRK1A signalling in cancer cells.

Abstract 346: A Novel Interaction Between E2F and β-adrenergic Pathways Regulates Survival and Growth in Murine Myocardium

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Jennifer L Major ◽  
Maysoon Salih ◽  
Balwant S Tuana
Keyword(s):  
Protein Kinase ◽  
Left Ventricle ◽  
Fold Increase ◽  
Negative Regulator ◽  
P Value ◽  
Specific Expression ◽  
Cardiac Growth ◽  
Reduced Ejection Fraction ◽  
Hypertrophic Growth ◽  
Rb Pathway

The E2F/Pocket protein (Rb) pathway regulates cell growth, differentiation, and death by modulating gene expression. We previously examined this pathway in myocardium via manipulation of E2F6, which represses gene activity independently of Rb. Mice with cardiac specific expression of E2F6 develop dilated cardiomyopathy (DCM) without any signs of hypertrophic growth. We assessed the mechanisms of the apparent failure of compensatory growth as well as their response to the β-adrenergic agonist isoproterenol (iso). E2F6 transgenic (Tg) mice present with left ventricle dilation and significantly reduced ejection fraction as early as 2 weeks which persists into adulthood, but with no apparent increase in left ventricle weight: body weight (LVW:BW). E2F6-Tg mice treated with iso show double the increase in LVW: BW than their Wt counterparts (32% vs 16%, p-value: 0.007). Western blot revealed a specific activation of the β2-adrenergic pathway in Tg myocardium under basal conditions including a ~2-fold increase in β2-adrenergic receptors (β2-AR) (p-value: 8.9E-05), protein kinase A catalytic subunit (PKA-C) (p-value: 0.0176), activated c-SRC tyrosine-protein kinase (p-value: 0.0002), and an induction of the anti-apoptotic gene Bcl2. In contrast, a ~70% decrease in the cardiac growth regulator: AKT1 (p-value 0.0001) and a 4-fold increase in cyclic AMP dependent phosphodiesterase 4D (PDE4D), the negative regulator of PKA activity, was evident in Tg myocardium. The expression of E2F3 was de-regulated by E2F6, but was restored by iso while Rb expression was down-regulated. Thus deregulation of E2F/Rb pathway by E2F6 altered the β-adrenergic signaling pathway such that survival signaling was activated while hypertrophy was repressed resulting in the development of DCM without any increase in muscle mass. These data reveal a novel interplay between E2F and the β adrenergic pathway which regulate cardiac growth and fate.

EXTH-55. TARGETING RECURRENT IDH MUTANT GLIOMA WITH CDK4/6 INHIBITION

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi175-vi175
Author(s):  
Julie Miller ◽  
Daniel Cahill ◽  
Lisa Melamed ◽  
Hiroaki Nagashima
Keyword(s):  
Gene Deletion ◽  
Homozygous Deletion ◽  
Therapeutic Strategies ◽  
Enhanced Sensitivity ◽  
Rb Pathway ◽  
Cancer Types ◽  
Xenograft Models ◽  
The Relationship ◽  
Inhibitor Treatment

Abstract Despite initial responsiveness to standard treatments like radiation and chemotherapy, IDH mutant gliomas inevitably recur, become more clinically aggressively and lead to untimely death. Recurrent IDH mutant tumors are less responsive to conventional treatments, highlighting the need for improved therapeutic strategies at this stage of the disease. At least 20% of recurrent IDH mutant gliomas exhibit homozygous loss of CDKN2A, which results in aberrant signaling through the CDK-RB pathway. We hypothesized that CDKN2A loss leads to enhanced sensitivity to CDK4/6 inhibitors, which are approved for use in a variety of other cancer types. We examined the relationship between CDK4/6 inhibitor sensitivity and CDKN2A loss using patient-derived models of IDH mutant glioma with endogenous CDKN2A homozygous deletion as well as with CRIPSR-mediated gene deletion. We observed enhanced cytotoxicity in glioma models with CDKN2A loss in vitro. Studies to examine the efficacy of CDK4/6 inhibitor treatment on slowing tumor growth in patient-derived xenograft models are ongoing. These preclinical results provide foundational data for design of a biomarker-driven clinical trial of CDK4/6 inhibitors in patients with recurrent IDH mutant glioma.

The APC tumor suppressor controls entry into S-phase through its ability to regulate the cyclin D/RB pathway

2002 ◽  
Vol 123 (3) ◽  
pp. 751-763 ◽  
Author(s):  
Christopher D. Heinen ◽  
Kathleen Heppner Goss ◽  
James R. Cornelius ◽  
George F. Babcock ◽  
Erik S. Knudsen ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
S Phase ◽  
Cyclin D ◽  
Rb Pathway

scholarly journals p53 promotes VEGF expression and angiogenesis in the absence of an intact p21-Rb pathway

2013 ◽  
Vol 20 (7) ◽  
pp. 888-897 ◽  
Author(s):  
M Farhang Ghahremani ◽  
S Goossens ◽  
D Nittner ◽  
X Bisteau ◽  
S Bartunkova ◽  
...  
Keyword(s):  
Vegf Expression ◽  
Rb Pathway

scholarly journals G1 arrest and differentiation can occur independently of Rb family function

2010 ◽  
Vol 191 (4) ◽  
pp. 809-825 ◽  
Author(s):  
Stacey E. Wirt ◽  
Adam S. Adler ◽  
Véronique Gebala ◽  
James M. Weimann ◽  
Bethany E. Schaffer ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Regulatory Networks ◽  
Target Genes ◽  
Family Members ◽  
Mouse Embryos ◽  
G1 Arrest ◽  
Cell Cycle Exit ◽  
Family Function ◽  
Rb Pathway

The ability of progenitor cells to exit the cell cycle is essential for proper embryonic development and homeostasis, but the mechanisms governing cell cycle exit are still not fully understood. Here, we tested the requirement for the retinoblastoma (Rb) protein and its family members p107 and p130 in G0/G1 arrest and differentiation in mammalian cells. We found that Rb family triple knockout (TKO) mouse embryos survive until days 9–11 of gestation. Strikingly, some TKO cells, including in epithelial and neural lineages, are able to exit the cell cycle in G0/G1 and differentiate in teratomas and in culture. This ability of TKO cells to arrest in G0/G1 is associated with the repression of key E2F target genes. Thus, G1 arrest is not always dependent on Rb family members, which illustrates the robustness of cell cycle regulatory networks during differentiation and allows for the identification of candidate pathways to inhibit the expansion of cancer cells with mutations in the Rb pathway.

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