scholarly journals Regulation of the mTERT telomerase catalytic subunit by the c-Abl tyrosine kinase in mouse granulosa cells

2019 ◽  
Author(s):  
Aylin Yaba ◽  
Sami Agus ◽  
Ecem Yildirim ◽  
Cihan S. Erdogan ◽  
Bayram Yilmaz

Abstract Background: Oocyte and granulosa cells (GCs) have bidirectional communication and GCs play an important role in folliculogenesis and proliferation of GCs is very important for the development of ovulatory follicle. DNA double-strand breaks activate c-Abl protein tyrosine kinase and c-Abl has a functional role in repairment of DNA and control of telomere. In this study, we hypothesized that c-Abl has a regulative role on mTERT in mouse ovarian granulosa cells (GCs) and we aimed to detect c-Abl and mTERT interaction in mouse primary culture of GCs. Results: We showed c-Abl and mTERT immunolocalization in vivo and in vitro mouse GCs. c-Abl and mTERT were constitutively expressed in mouse granulosa cells and c-Abl presented more intense expression in granulosa cells than mTERT expression. The interaction of the c-Abl-mTERT is supported by the exhibition that c-Abl siRNA knockdown cells show decreased mTERT expression. We also present an interaction between c-Abl and mTERT by immunoprecipitation. In addition, our results indicated that the down-regulation of c-Abl was also accompanied by reduced expression of proliferating cell nuclear antigen (PCNA) in GCs. Conclusions: We suggest that mTERT may associate with the c-Abl in mouse GCs and the interactions between c-Abl and mTERT suggest a role for c-Abl in the regulation of telomerase function and proliferation in mouse granulosa cells during folliculogenesis.

2019 ◽  
Author(s):  
Aylin Yaba ◽  
Sami Agus ◽  
Ecem Yildirim ◽  
Cihan S. Erdogan ◽  
Bayram Yilmaz

Abstract Background: DNA double-strand breaks activate c-Abl protein tyrosine kinase and c-Abl has functional role in repairment of DNA and control of telomere. In this study we hypothesized that c-Abl has regulative role on mTERT in mouse ovarian granulosa cells (GCs) and we aimed to detect c-Abl and mTERT interaction in mouse primary culture of GCs. We showed c-Abl and mTERT immunolocalization in vivo and in vitro mouse GCs. Results: c-Abl presented more intense expression in granulosa cells than mTERT expression. The interaction of the c-Abl–mTERT is supported by the exhibition that c-Abl siRNA knockdown cells show decreased mTERT expression. In addition, our results indicated that the downregulation of c-Abl was also accompanied by reduced expression of proliferating cell nuclear antigen (PCNA) in GCs. We also present interaction between c-Abl and mTERT by immunoprecipitation. Conclusions: We suggest that mTERT may associate with the c-Abl in mouse GCs and the interactions between c-Abl and mTERT suggest a role for c-Abl in the regulation of telomerase function and genomic stability in mouse granulosa cells during folliculogenesis.


Blood ◽  
2006 ◽  
Vol 108 (5) ◽  
pp. 1716-1723 ◽  
Author(s):  
Lynn McCallum ◽  
Susan Price ◽  
Nathalie Planque ◽  
Bernard Perbal ◽  
Andrew Pierce ◽  
...  

Chronic myeloid leukemia (CML) is characterized by the presence of the constitutively active BCR-ABL protein tyrosine kinase. Using a multipotent hemopoietic cell line, FDCP-Mix, expressing BCR-ABL tyrosine kinase, we investigated the initial effects of this kinase in primitive hematopoietic stem cells. We identified down-regulation of a novel gene, CCN3, as a direct consequence of BCR-ABL kinase activity. CCN3 has been reported to function as a tumor suppressor gene in solid tumors. Northern and Western blotting plus immunocytochemical analysis confirmed CCN3 expression is decreased and is tyrosine-phosphorylated in BCR-ABL kinase active FDCP-Mix cells. Decreased cellular CCN3 correlated with increased CCN3 secretion in BCR-ABL kinase active cells. In vitro treatment of human CML cell lines with imatinib or siRNA directed against BCR-ABL significantly reduced BCR-ABL while increasing CCN3 expression. Cells from patients responding to imatinib showed a similar decrease in BCR-ABL and increase in CCN3. CML CD34+ cells treated with imatinib in vitro demonstrated increased CCN3 protein. Transfecting CCN3 into BCR-ABL+ cells inhibited proliferation and decreased clonogenic potential. CCN3 plays an important role in internal and external cell-signaling pathways. Thus, BCR-ABL can regulate protein levels by governing secretion, a novel mechanism for this tyrosine kinase.


2004 ◽  
Vol 24 (21) ◽  
pp. 9351-9358 ◽  
Author(s):  
Charles E. Laurent ◽  
Frank J. Delfino ◽  
Haiyun Y. Cheng ◽  
Thomas E. Smithgall

ABSTRACT The c-Fes protein-tyrosine kinase (Fes) has been implicated in the differentiation of vascular endothelial, myeloid hematopoietic, and neuronal cells, promoting substantial morphological changes in these cell types. The mechanism by which Fes promotes morphological aspects of cellular differentiation is unknown. Using COS-7 cells as a model system, we observed that Fes strongly colocalizes with microtubules in vivo when activated via coiled-coil mutation or by coexpression with an active Src family kinase. In contrast, wild-type Fes showed a diffuse cytoplasmic localization in this system, which correlated with undetectable kinase activity. Coimmunoprecipitation and immunofluorescence microscopy showed that the N-terminal Fes/CIP4 homology (FCH) domain is involved in Fes interaction with soluble unpolymerized tubulin. However, the FCH domain was not required for colocalization with polymerized microtubules in vivo. In contrast, a functional SH2 domain was essential for microtubule localization of Fes, consistent with the strong tyrosine phosphorylation of purified tubulin by Fes in vitro. Using a microtubule nucleation assay, we observed that purified c-Fes also catalyzed extensive tubulin polymerization in vitro. Taken together, these results identify c-Fes as a regulator of the tubulin cytoskeleton that may contribute to Fes-induced morphological changes in myeloid hematopoietic and neuronal cells.


1994 ◽  
Vol 14 (5) ◽  
pp. 2883-2894 ◽  
Author(s):  
B J Mayer ◽  
D Baltimore

We have used in vitro mutagenesis to examine in detail the roles of two modular protein domains, SH2 and SH3, in the regulation of the Abl tyrosine kinase. As previously shown, the SH3 domain suppresses an intrinsic transforming activity of the normally nontransforming c-Abl product in vivo. We show here that this inhibitory activity is extremely position sensitive, because mutants in which the position of the SH3 domain within the protein is subtly altered are fully transforming. In contrast to the case in vivo, the SH3 domain has no effect on the in vitro kinase activity of the purified protein. These results are consistent with a model in which the SH3 domain binds a cellular inhibitory factor, which in turn must physically interact with other parts of the kinase. Unlike the SH3 domain, the SH2 domain is required for transforming activity of activated Abl alleles. We demonstrate that SH2 domains from other proteins (Ras-GTPase-activating protein, Src, p85 phosphatidylinositol 3-kinase subunit, and Crk) can complement the absence of the Abl SH2 domain and that mutants with heterologous SH2 domains induce altered patterns of tyrosine-phosphorylated proteins in vivo. The positive function of the SH2 domain is relatively position independent, and the effect of multiple SH2 domains appears to be additive. These results suggest a novel mechanism for regulation of tyrosine kinases in which the SH2 domain binds to, and thereby enhances the phosphorylation of, a subset of proteins phosphorylated by the catalytic domain. Our data also suggest that the roles of the SH2 and SH3 domains in the regulation of Abl are different in several respects from the roles proposed for these domains in the closely related Src family of tyrosine kinases.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 761-761 ◽  
Author(s):  
Shinya Kimura ◽  
Hidekazu Segawa ◽  
Junya Kuroda ◽  
Takeshi Yuasa ◽  
Taira Maekawa

Abstract Imatinib mesylate (also known as STI-571 and Gleevec) has drastically changed the treatment of Philadelphia chromosome positive (Ph+) leukemias. However, the resistance to imatinib has frequently been reported, particularly in patients with advanced-stage disease. A novel orally bioavailable inhibitor of the ABL tyrosine kinase (TK) named CNS-9 was developed from the 2-(phenylamino)pyrimidine class to overcome resistance mechanisms of imatinib. Inhibition of TK phosphorylation (IC50) on wild type (wt) BCR/ABL in 293T cell line by CNS-9 was 22nM, which was 2-log more potent than imatinib. Importantly, CNS-9 inhibited TK phosphorylation of E255K mutant BCR/ABL with IC50 of 98nM, while imatinib could not inhibit it with clinically relevant concentration. The T315I mutant BCR/ABL protein was resistant to CNS-9 and imatinib. CNS-9 also inhibited TK phosphorylation of platelet-derived growth factor receptor (PDGFR) or c-Kit pathways at the very similar observed IC50s when compared with imatinib, in spite of significant higher potency against ABL. The ability of CNS-9 in vitro to inhibit 101 TK molecules was assayed by KinaseProfilerTM (Upstate), showing also more specific inhibitory activity against ABL than imatinib. The growth of BCR/ABL-positive cell lines K562, KU812, BaF3 harboring wt BCR/ABL (BaF3/wt) and E255K (BaF3/E255K) was inhibited by CNS-9 with IC50 of 5, 3, 17, and 110nM, respectively (Table 1). Generally, CNS-9 was 20 to 30-fold more potent on the growth inhibition than imatinib in these same cell lines. We next investigated the in vivo effect on the leukemic growth inhibition of CNS-9. Nude mice were injected subcutaneously with 3x107 KU812 (wt BCR/ABL) on Day 0. CNS-9 or imatinib were orally administrated twice a day from Day 7 to Day 18. The dosages of CNS-9 and imatinib, which inhibited completely tumor growth were 20mg/kg/day and 200mg/kg/day, respectively, indicating that CNS-9 is 10-fold potent than imatinib in vivo. To examine the in vivo effect of CNS-9 against mutant BCR/ABL, BaF3/wt, BaF3/E255K or BaF3/T315I were engrafted to nude mice and treated with CNS-9 or imatinib. CNS-9 was also 10-fold potent than imatinib against BaF3/wt. Intriguingly, mice harboring BaF3/wt or BaF3/E255K showed significantly prolonged survival when treated with CNS-9. Consistent with in vitro assay, CNS-9 had no effect on T315I, and imatinib was not effective against both E255K and T315I. In conclusion, CNS-9 is substantially more inhibitory and more specifically than imatinib toward BCR/ABL-dependent cell growth both in vitro and in vivo Moreover, CNS-9 may be effective for leukemia patients whose leukemic cells harbor E255K mutant. The efficacy and safety of CNS-9 for Ph+ leukemias should be verified in early phase clinical trials. The IC50s values of leukemic cell lines for CNS-9 and imatinib CNS-9 (nM) imatinib (nM) K562 p210 wt BCR/ABL 5 130 KU812 p210 wt BCR/ABL 3 67 U937 BCR/ABL (−) >1000 >1000 BaF3 p190 wt BCR/ABL 17 360 BaF3 p190 E255K BCR/ABL 110 >1000 BaF3 p190 T315I BCR/ABL >1000 >1000


1999 ◽  
Vol 19 (12) ◽  
pp. 8335-8343 ◽  
Author(s):  
Haiyun Cheng ◽  
Jim A. Rogers ◽  
Nancy A. Dunham ◽  
Thomas E. Smithgall

ABSTRACT The cytoplasmic protein-tyrosine kinase Fes has been implicated in cytokine signal transduction, hematopoiesis, and embryonic development. Previous work from our laboratory has shown that active Fes exists as a large oligomeric complex in vitro. However, when Fes is expressed in mammalian cells, its kinase activity is tightly repressed. The Fes unique N-terminal sequence has two regions with strong homology to coiled-coil-forming domains often found in oligomeric proteins. Here we show that disruption or deletion of the first coiled-coil domain upregulates Fes tyrosine kinase and transforming activities in Rat-2 fibroblasts and enhances Fes differentiation-inducing activity in myeloid leukemia cells. Conversely, expression of a Fes truncation mutant consisting only of the unique N-terminal domain interfered with Rat-2 fibroblast transformation by an activated Fes mutant, suggesting that oligomerization is essential for Fes activation in vivo. Coexpression with the Fes N-terminal region did not affect the transforming activity of v-Src in Rat-2 cells, arguing against a nonspecific suppressive effect. Taken together, these findings suggest a model in which Fes activation may involve coiled-coil-mediated interconversion of monomeric and oligomeric forms of the kinase. Mutation of the first coiled-coil domain may activate Fes by disturbing intramolecular coiled-coil interaction, allowing for oligomerization via the second coiled-coil domain. Deletion of the second coiled-coil domain blocks fibroblast transformation by an activated form of c-Fes, consistent with this model. These results provide the first evidence for regulation of a nonreceptor protein-tyrosine kinase by coiled-coil domains.


Author(s):  
Ting-Ting Huang ◽  
Xin Wang ◽  
Shao-Jia Qiang ◽  
Zhen-Nan Zhao ◽  
Zhuo-Xun Wu ◽  
...  

Chronic myelogenous leukemia (CML) typically results from a reciprocal translocation between chromosomes 9 and 22 to produce the bcr-abl oncogene that when translated, yields the p210 BCR-ABL protein in more than 90% of all CML patients. This protein has constitutive tyrosine kinase activity that activates numerous downstream pathways that ultimately produces uncontrolled myeloid proliferation. Although the use of the BCR-ABL tyrosine kinase inhibitors (TKIs), such as imatinib, nilotinib, dasatinib, bosutinib, and ponatinib have increased the overall survival of CML patients, their use is limited by drug resistance and severe adverse effects. Therefore, there is the need to develop novel compounds that can overcome these problems that limit the use of these drugs. Therefore, in this study, we sought to find novel compounds using Hypogen and Hiphip pharmacophore models based on the structures of clinically approved BCR-ABL TKIs. We also used optimal pharmacophore models such as three-dimensional queries to screen the ZINC database to search for potential BCR-ABL inhibitors. The hit compounds were further screened using Lipinski’s rule of five, ADMET and molecular docking, and the efficacy of the hit compounds was evaluated. Our in vitro results indicated that compound ZINC21710815 significantly inhibited the proliferation of K562, BaF3/WT, and BaF3/T315I leukemia cells by inducing cell cycle arrest. The compound ZINC21710815 decreased the expression of p-BCR-ABL, STAT5, and Crkl and produced apoptosis and autophagy. Our results suggest that ZINC21710815 may be a potential BCR-ABL inhibitor that should undergo in vivo evaluation.


1985 ◽  
Vol 5 (11) ◽  
pp. 3116-3123
Author(s):  
J B Konopka ◽  
O N Witte

The v-abl transforming protein P160v-abl and the P210c-abl gene product of the translocated c-abl gene in Philadelphia chromosome-positive chronic myelogenous leukemia cells have tyrosine-specific protein kinase activity. Under similar assay conditions the normal c-abl gene products, murine P150c-abl and human P145c-abl, lacked detectable kinase activity. Reaction conditions were modified to identify conditions which would permit the detection of c-abl tyrosine kinase activity. It was found that the Formalin-fixed Staphylococcus aureus formerly used for immunoprecipitation inhibits in vitro abl kinase activity. In addition, the sodium dodecyl sulfate and deoxycholate detergents formerly used in the cell lysis buffer were found to decrease recovered abl kinase activity. The discovery of assay conditions for c-abl kinase activity now makes it possible to compare P150c-abl and P145c-abl kinase activity with the altered abl proteins P160v-abl and P210c-abl. Although all of the abl proteins have in vitro tyrosine kinase activity, they differ in the way they utilize themselves as substrates in vitro. Comparison of in vitro and in vivo tyrosine phosphorylation sites of the abl proteins suggests that they function differently in vivo. The development of c-abl kinase assay conditions should be useful in elucidating c-abl function.


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