The Experts below are selected from a list of 693 Experts worldwide ranked by ideXlab platform
Leslie V Parise - One of the best experts on this subject based on the ideXlab platform.
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Discovery and Characterization of Peptide Inhibitors for CIB1.
ACS Chemical Biology, 2020Co-Authors: Ana C. Puhl, Tina M. Leisner, Jonathan W. Bogart, Victoria A Haberman, Jacob E. Larson, Andre S. Godoy, Jacqueline Norris-drouin, Stephanie H. Cholensky, Stephen V. Frye, Leslie V PariseAbstract:: Calcium and integrin binding protein 1 (CIB1) is an EF-hand-containing, small intracellular protein that has recently been implicated in cancer cell survival and proliferation. In particular, CIB1 depletion significantly impairs tumor growth in triple-negative breast cancer (TNBC). Thus, CIB1 is a potentially attractive target for cancer chemotherapy that has yet to be validated by a chemical probe. To produce a probe molecule to the CIB1 helix 10 (H10) pocket and demonstrate that it is a viable feature for molecular intervention, we employed random peptide phage display to screen and select CIB1-binding peptides. The top peptide sequence selected, UNC10245092, was produced synthetically and binding to CIB1 was confirmed by isothermal titration calorimetry (ITC) and a time-resolved fluorescence resonance energy transfer (TR-FRET) assay. Both assays showed that the peptide bound to CIB1 with low nanomolar affinity. CIB1 was co-crystallized with UNC10245092, and the 2.1 A resolution structure revealed that the peptide binds as an α-helix in the H10 pocket, displacing the CIB1 C-terminal H10 helix and causing conformational changes in H7 and H8. UNC10245092 was further derivatized with a C-terminal Tat-derived cell penetrating peptide (CPP) to demonstrate its effects on TNBC cells in culture, which are consistent with results of CIB1 depletion. These studies provide a first-in-class chemical tool for CIB1 inhibition in cell culture and validate the CIB1 H10 pocket for future probe and drug development efforts.
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Targeted Delivery of siRNA Lipoplexes to Cancer Cells Using Macrophage Transient Horizontal Gene Transfer
Advanced Science, 2019Co-Authors: Elizabeth C. Wayne, Leslie V Parise, Tina M. Leisner, Christian Long, Matthew J. Haney, Elena V. Batrakova, Alexander V. KabanovAbstract:: Delivery of nucleic acids into solid tumor environments remains a pressing challenge. This study examines the ability of macrophages to horizontally transfer small interfering RNA (siRNA) lipoplexes to cancer cells. Macrophages are a natural candidate for a drug carrier because of their ability to accumulate at high densities into many cancer types, including, breast, prostate, brain, and colon cancer. Here, it is demonstrated that macrophages can horizontally transfer siRNA to cancer cells during in vitro coculture. The amount of transfer can be dosed depending on the amount of siRNA loaded and total number of macrophages delivered. Macrophages loaded with calcium integrin binding protein-1 (CIB1)-siRNA result in decreased tumorsphere growth and decreased mRNA expression of CIB1 and KI67 in MDA-MB-468 human breast cancer cells. Adoptive transfer of macrophages transfected with CIB1-siRNA localizes to the orthotopic MDA-MB-468 tumor. Furthermore, it is reported that macrophage activation can modulate this transfer process as well as intracellular trafficking protein Rab27a. As macrophages are heavily involved in tumor progression, understanding how to use macrophages for drug delivery can substantially benefit the treatment of tumors.
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CIB1 depletion with docetaxel or trail enhances triple negative breast cancer cell death
Cancer Cell International, 2019Co-Authors: Alexander H Chung, Tina M. Leisner, Gabrielle J Dardis, Marissa M Bivins, Alana L Keller, Leslie V PariseAbstract:Patients diagnosed with triple negative breast cancer (TNBC) have limited treatment options and often suffer from resistance and toxicity due to chemotherapy. We previously found that depleting calcium and integrin-binding protein 1 (CIB1) induces cell death selectively in TNBC cells, while sparing normal cells. Therefore, we asked whether CIB1 depletion further enhances tumor-specific killing when combined with either the commonly used chemotherapeutic, docetaxel, or the cell death-inducing ligand, TRAIL. We targeted CIB1 by RNA interference in MDA-MB-436, MDA-MB-231, MDA-MB-468, docetaxel-resistant MDA-MB-436 TNBC cells and ME16C normal breast epithelial cells alone or combination with docetaxel or TRAIL. Cell death was quantified via trypan blue exclusion using flow cytometry and cell death mechanisms were analyzed by Western blotting. Cell surface levels of TRAIL receptors were measured by flow cytometry analysis. CIB1 depletion combined with docetaxel significantly enhanced tumor-specific cell death relative to each treatment alone. The enhanced cell death strongly correlated with caspase-8 activation, a hallmark of death receptor-mediated apoptosis. The death receptor TRAIL-R2 was upregulated in response to CIB1 depletion, which sensitized TNBC cells to the ligand TRAIL, resulting in a synergistic increase in cell death. In addition to death receptor-mediated apoptosis, both combination treatments activated a non-apoptotic mechanism, called paraptosis. Interestingly, these combination treatments also induced nearly complete death of docetaxel-resistant MDA-MB-436 cells, again via apoptosis and paraptosis. In contrast, neither combination treatment induced cell death in normal ME16C cells. Novel combinations of CIB1 depletion with docetaxel or TRAIL selectively enhance naive and docetaxel-resistant TNBC cell death while sparing normal cell. Therefore, combination therapies that target CIB1 could prove to be a safe and durable strategy for treatment of TNBC and potentially other cancers.
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CIB1 protects against mptp induced neurotoxicity through inhibiting ask1
Scientific Reports, 2017Co-Authors: Leslie V Parise, Ulhas P. Naik, Kyoung Wan Yoon, Hyun Suk Yang, Seong Man Kang, Eui Ju ChoiAbstract:Calcium and integrin binding protein 1 (CIB1) is a calcium-binding protein that was initially identified as a binding partner of platelet integrin αIIb. Although CIB1 has been shown to interact with multiple proteins, its biological function in the brain remains unclear. Here, we show that CIB1 negatively regulates degeneration of dopaminergic neurons in a mouse model of Parkinson’s disease using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Genetic deficiency of the CIB1 gene enhances MPTP-induced neurotoxicity in dopaminergic neurons in CIB1−/− mice. Furthermore, RNAi-mediated depletion of CIB1 in primary dopaminergic neurons potentiated 1-methyl-4-phenyl pyrinidium (MPP+)-induced neuronal death. CIB1 physically associated with apoptosis signal-regulating kinase 1 (ASK1) and thereby inhibited the MPP+-induced stimulation of the ASK1-mediated signaling cascade. These findings suggest that CIB1 plays a protective role in MPTP/MPP+-induced neurotoxicity by blocking ASK1-mediated signaling.
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CIB1 contributes to oncogenic signalling by ras via modulating the subcellular localisation of sphingosine kinase 1
Oncogene, 2017Co-Authors: Briony L. Gliddon, Leslie V Parise, Kate E. Jarman, Paul A.b. Moretti, J M Woodcock, J A Powell, A Ruszkiewicz, Melissa R. PitmanAbstract:CIB1 contributes to oncogenic signalling by Ras via modulating the subcellular localisation of sphingosine kinase 1
Tina M. Leisner - One of the best experts on this subject based on the ideXlab platform.
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Discovery and Characterization of Peptide Inhibitors for CIB1.
ACS Chemical Biology, 2020Co-Authors: Ana C. Puhl, Tina M. Leisner, Jonathan W. Bogart, Victoria A Haberman, Jacob E. Larson, Andre S. Godoy, Jacqueline Norris-drouin, Stephanie H. Cholensky, Stephen V. Frye, Leslie V PariseAbstract:: Calcium and integrin binding protein 1 (CIB1) is an EF-hand-containing, small intracellular protein that has recently been implicated in cancer cell survival and proliferation. In particular, CIB1 depletion significantly impairs tumor growth in triple-negative breast cancer (TNBC). Thus, CIB1 is a potentially attractive target for cancer chemotherapy that has yet to be validated by a chemical probe. To produce a probe molecule to the CIB1 helix 10 (H10) pocket and demonstrate that it is a viable feature for molecular intervention, we employed random peptide phage display to screen and select CIB1-binding peptides. The top peptide sequence selected, UNC10245092, was produced synthetically and binding to CIB1 was confirmed by isothermal titration calorimetry (ITC) and a time-resolved fluorescence resonance energy transfer (TR-FRET) assay. Both assays showed that the peptide bound to CIB1 with low nanomolar affinity. CIB1 was co-crystallized with UNC10245092, and the 2.1 A resolution structure revealed that the peptide binds as an α-helix in the H10 pocket, displacing the CIB1 C-terminal H10 helix and causing conformational changes in H7 and H8. UNC10245092 was further derivatized with a C-terminal Tat-derived cell penetrating peptide (CPP) to demonstrate its effects on TNBC cells in culture, which are consistent with results of CIB1 depletion. These studies provide a first-in-class chemical tool for CIB1 inhibition in cell culture and validate the CIB1 H10 pocket for future probe and drug development efforts.
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Targeted Delivery of siRNA Lipoplexes to Cancer Cells Using Macrophage Transient Horizontal Gene Transfer
Advanced Science, 2019Co-Authors: Elizabeth C. Wayne, Leslie V Parise, Tina M. Leisner, Christian Long, Matthew J. Haney, Elena V. Batrakova, Alexander V. KabanovAbstract:: Delivery of nucleic acids into solid tumor environments remains a pressing challenge. This study examines the ability of macrophages to horizontally transfer small interfering RNA (siRNA) lipoplexes to cancer cells. Macrophages are a natural candidate for a drug carrier because of their ability to accumulate at high densities into many cancer types, including, breast, prostate, brain, and colon cancer. Here, it is demonstrated that macrophages can horizontally transfer siRNA to cancer cells during in vitro coculture. The amount of transfer can be dosed depending on the amount of siRNA loaded and total number of macrophages delivered. Macrophages loaded with calcium integrin binding protein-1 (CIB1)-siRNA result in decreased tumorsphere growth and decreased mRNA expression of CIB1 and KI67 in MDA-MB-468 human breast cancer cells. Adoptive transfer of macrophages transfected with CIB1-siRNA localizes to the orthotopic MDA-MB-468 tumor. Furthermore, it is reported that macrophage activation can modulate this transfer process as well as intracellular trafficking protein Rab27a. As macrophages are heavily involved in tumor progression, understanding how to use macrophages for drug delivery can substantially benefit the treatment of tumors.
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CIB1 depletion with docetaxel or trail enhances triple negative breast cancer cell death
Cancer Cell International, 2019Co-Authors: Alexander H Chung, Tina M. Leisner, Gabrielle J Dardis, Marissa M Bivins, Alana L Keller, Leslie V PariseAbstract:Patients diagnosed with triple negative breast cancer (TNBC) have limited treatment options and often suffer from resistance and toxicity due to chemotherapy. We previously found that depleting calcium and integrin-binding protein 1 (CIB1) induces cell death selectively in TNBC cells, while sparing normal cells. Therefore, we asked whether CIB1 depletion further enhances tumor-specific killing when combined with either the commonly used chemotherapeutic, docetaxel, or the cell death-inducing ligand, TRAIL. We targeted CIB1 by RNA interference in MDA-MB-436, MDA-MB-231, MDA-MB-468, docetaxel-resistant MDA-MB-436 TNBC cells and ME16C normal breast epithelial cells alone or combination with docetaxel or TRAIL. Cell death was quantified via trypan blue exclusion using flow cytometry and cell death mechanisms were analyzed by Western blotting. Cell surface levels of TRAIL receptors were measured by flow cytometry analysis. CIB1 depletion combined with docetaxel significantly enhanced tumor-specific cell death relative to each treatment alone. The enhanced cell death strongly correlated with caspase-8 activation, a hallmark of death receptor-mediated apoptosis. The death receptor TRAIL-R2 was upregulated in response to CIB1 depletion, which sensitized TNBC cells to the ligand TRAIL, resulting in a synergistic increase in cell death. In addition to death receptor-mediated apoptosis, both combination treatments activated a non-apoptotic mechanism, called paraptosis. Interestingly, these combination treatments also induced nearly complete death of docetaxel-resistant MDA-MB-436 cells, again via apoptosis and paraptosis. In contrast, neither combination treatment induced cell death in normal ME16C cells. Novel combinations of CIB1 depletion with docetaxel or TRAIL selectively enhance naive and docetaxel-resistant TNBC cell death while sparing normal cell. Therefore, combination therapies that target CIB1 could prove to be a safe and durable strategy for treatment of TNBC and potentially other cancers.
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CIB1 a small protein with big ambitions
The FASEB Journal, 2016Co-Authors: Tina M. Leisner, Justin L. Black, Thomas C Freeman, Leslie V PariseAbstract:Calcium- and integrin-binding protein 1 (CIB1) is a small, ubiquitously expressed protein that was first identified as an intracellular binding partner of a platelet-specific α-integrin cytoplasmic tail. Although early studies revealed a role for CIB1 in regulating platelet integrin activity, recent studies have indicated a more diverse role for CIB1 in many different cell types and processes, including calcium signaling, migration, adhesion, proliferation, and survival. Increasing evidence also points to a novel role for CIB1 in cancer and cardiovascular disease. In addition, an array of CIB1 binding partners has been identified that provide important insight into how CIB1 may regulate these processes. Some of these binding partners include the serine/threonine kinases, p21-activated kinase 1 (PAK1), apoptosis signal-regulating kinase 1 (ASK1), and polo-like kinase 3 (PLK3). Structural and mutational studies indicate that CIB1 binds most or all of its partners via a well-defined hydrophobic cleft. Althou...
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CIB1 depletion impairs cell survival and tumor growth in triple-negative breast cancer
Breast Cancer Research and Treatment, 2015Co-Authors: Justin L. Black, J. Chuck Harrell, Tina M. Leisner, Melissa J. Fellmeth, Samuel D. George, Dominik Reinhold, Nicole M. Baker, Corbin D. Jones, Charles M. Perou, Leslie V PariseAbstract:Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with generally poor prognosis and no available targeted therapies, highlighting a critical unmet need to identify and characterize novel therapeutic targets. We previously demonstrated that CIB1 is necessary for cancer cell survival and proliferation via regulation of two oncogenic signaling pathways, RAF–MEK–ERK and PI3K–AKT. Because these pathways are often upregulated in TNBC, we hypothesized that CIB1 may play a broader role in TNBC cell survival and tumor growth. Methods utilized include inducible RNAi depletion of CIB1 in vitro and in vivo, immunoblotting, clonogenic assay, flow cytometry, RNA-sequencing, bioinformatics analysis, and Kaplan–Meier survival analysis. CIB1 depletion resulted in significant cell death in 8 of 11 TNBC cell lines tested. Analysis of components related to PI3K–AKT and RAF–MEK–ERK signaling revealed that elevated AKT activation status and low PTEN expression were key predictors of sensitivity to CIB1 depletion. Furthermore, CIB1 knockdown caused dramatic shrinkage of MDA-MB-468 xenograft tumors in vivo. RNA sequence analysis also showed that CIB1 depletion in TNBC cells activates gene programs associated with decreased proliferation and increased cell death. CIB1 expression levels per se did not predict TNBC susceptibility to CIB1 depletion, and CIB1 mRNA expression levels did not associate with TNBC patient survival. Our data are consistent with the emerging concept of non-oncogene addiction, where a large subset of TNBCs depend on CIB1 for cell survival and tumor growth, independent of CIB1 expression levels. Our data establish CIB1 as a novel therapeutic target for TNBC.
Ulhas P. Naik - One of the best experts on this subject based on the ideXlab platform.
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calcium induced dissociation of CIB1 from ask1 regulates agonist induced activation of the p38 mapk pathway in platelets
Biochemical Journal, 2019Co-Authors: Pravin Patel, Meghna U. Naik, Kalyan Golla, Noor F Shaik, Ulhas P. NaikAbstract:: Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that regulates activation of the c-Jun N-terminal kinase (JNK)- and p38-stress response pathways leading to apoptosis in nucleated cells. We have previously shown that ASK1 is expressed in platelets and regulates agonist-induced platelet activation and thrombosis. However, the mechanism by which platelet agonists cause activation of ASK1 is unknown. Here, we show that in platelets agonist-induced activation of p38 is exclusively dependent on ASK1. Both thrombin and collagen were able to activate ASK1/p38. Activation of ASK1/p38 was strongly dependent on thromboxane A2 (TxA2) and ADP. Agonist-induced ASK1 activation is blocked by inhibition of phospholipase C (PLC) β/γ activity or by chelating intracellular Ca2+. Furthermore, treatment of platelets with thapsigargin or Ca2+ ionophore robustly induced ASK1/p38 activation. In addition, calcium and integrin-binding protein 1 (CIB1), a Ca2+-dependent negative regulator of ASK1, associates with ASK1 in resting platelets and is dissociated upon platelet activation by thrombin. Dissociation of CIB1 corresponds with ASK1 binding to tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6) and the autophosphorylation of ASK1 Thr838 within the catalytic domain results in full activation of ASK1. Furthermore, genetic ablation of CIB1 in mice augments agonist-induced Ask1/p38 activation. Together our results suggest that in resting platelets ASK1 is bound to CIB1 at low Ca2+ concentrations. Agonist-induced platelet activation causes an increase in intracellular Ca2+ concentration that leads to the dissociation of CIB1 from ASK1, allowing for proper dimerization through ASK1 N-terminal coiled-coil (NCC) domains.
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CIB1 protects against mptp induced neurotoxicity through inhibiting ask1
Scientific Reports, 2017Co-Authors: Leslie V Parise, Ulhas P. Naik, Kyoung Wan Yoon, Hyun Suk Yang, Seong Man Kang, Eui Ju ChoiAbstract:Calcium and integrin binding protein 1 (CIB1) is a calcium-binding protein that was initially identified as a binding partner of platelet integrin αIIb. Although CIB1 has been shown to interact with multiple proteins, its biological function in the brain remains unclear. Here, we show that CIB1 negatively regulates degeneration of dopaminergic neurons in a mouse model of Parkinson’s disease using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Genetic deficiency of the CIB1 gene enhances MPTP-induced neurotoxicity in dopaminergic neurons in CIB1−/− mice. Furthermore, RNAi-mediated depletion of CIB1 in primary dopaminergic neurons potentiated 1-methyl-4-phenyl pyrinidium (MPP+)-induced neuronal death. CIB1 physically associated with apoptosis signal-regulating kinase 1 (ASK1) and thereby inhibited the MPP+-induced stimulation of the ASK1-mediated signaling cascade. These findings suggest that CIB1 plays a protective role in MPTP/MPP+-induced neurotoxicity by blocking ASK1-mediated signaling.
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binding of CIB1 to the αiib tail of αiibβ3 is required for fak recruitment and activation in platelets
PLOS ONE, 2017Co-Authors: Meghna U. Naik, Tejal U Naik, Ross Summer, Ulhas P. NaikAbstract:Background It is believed that activation of c-Src bound to the integrin β3 subunit initiates outside-in signaling. The involvement of αIIb in outside-in signaling is poorly understood. Objectives We have previously shown that CIB1 specifically interacts with the cytoplasmic domain of αIIb and is required for αIIbβ3 outside-in signaling. Here we evaluated the role of CIB1 in regulating outside-in signaling in the absence of inside-out signaling. Methods We used αIIb cytoplasmic domain peptide and CIB1-function blocking antibody to inhibit interaction of CIB1 with αIIb subunit as well as CIB1-/- platelets to evaluate the consequence of CIB1 interaction with αIIb on outside-in signaling. Results Fibrinogen binding to αIIbβ3 results in calcium-dependent interaction of CIB1 with αIIb, which is not required for filopodia formation. Dynamic rearrangement of cytoskeleton results in CIB1-dependent recruitment of FAK to the αIIb complex and its activation. Disruption of the association of CIB1 and αIIb by incorporation of αIIb peptide or anti-CIB1 inhibited both FAK association and activation. Furthermore, FAK recruitment to the integrin complex was required for c-Src activation. Inhibition of c-Src had no effect on CIB1 accumulation with the integrin at the filopodia, suggesting that c-Src activity is not required for the formation of CIB1-αIIb-FAK complex. Conclusion Our results suggest that interaction of CIB1 with αIIb is one of the early events occurring during outside-in signaling. Furthermore, CIB1 recruits FAK to the αIIbβ3 complex at the filopodia where FAK is activated, which in turn activates c-Src, resulting in propagation of outside-in signaling leading to platelet spreading.
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Integrin αIIb cytoplasmic Tail Is Essential for Integrin Outside-in Signaling and Regulation of in Vivo Thrombosis
Blood, 2014Co-Authors: Meghna U. Naik, Ulhas P. NaikAbstract:Platelet aggregation plays an important role in physiological hemostasis and pathological thrombosis. Platelet agonists induce a series of events called inside-out signaling that lead to the activation of integrin αIIbβ3. Fibrinogen binding to the activated integrin relay signals termed as outside-in signaling that regulate thrombus growth and stability. Talin and kindlin bind to the integrin β3 cytoplasmic tail to induce inside-out signaling. Although, integrin αIIb cytoplasmic domain also bind to a number of proteins, its importance in hemostasis or thrombosis is not well understood. Previously, we have identified a calcium- and integrin-binding protein (CIB1) that specifically interacts with the integrin αIIb cytoplasmic tail. Using a novel technique to inhibit interaction of CIB1 with integrin αIIb in intact human platelets, we have shown that CIB1 regulates outside-in signaling through integrin αIIbβ3. Recently, using CIB1-/- mice, we showed that CIB1 is a key regulator of thrombosis in vivo . Interestingly, agonist-induced platelet aggregation and secretion was normal in CIB1-/- platelets. Furthermore, expression or activation of integrin αIIbβ3 was also not affected by CIB1 deficiency, suggesting that integrin inside-out signaling is not affected in CIB1-/- platelets. However, adhesion and spreading on immobilized fibrinogen (Fg) was severely affected in CIB1-/- platelets. When we analyzed the rate of clot retraction, we found that significantly ( P
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Calcium- and integrin-binding protein 1 regulates megakaryocyte ploidy, adhesion, and migration
Blood, 2011Co-Authors: John C. Kostyak, Meghna U. Naik, Ulhas P. NaikAbstract:Megakaryocytes are large, polyploid cells that produce platelets. We have previously reported that calcium- and integrin-binding protein 1 (CIB1) regulates endomitosis in Dami cells. To further characterize the role of CIB1 in megakaryopoiesis, we used a CIB1−/− mouse model. CIB1−/− mice have more platelets and BM megakaryocytes than wild-type (WT) controls (P < .05). Furthermore, subsequent analysis of megakaryocyte-CFU production revealed an increase with CIB1 deletion compared with WT (P < .05). In addition, BM from CIB1−/− mice, cultured with thrombopoietin (TPO) for 24 hours, produced more highly polyploid megakaryocytes than WT BM (P < .05). Subsequent analysis of TPO signaling revealed enhanced Akt and ERK1/2 phosphorylation, whereas FAKY925 phosphorylation was reduced in CIB1−/− megakaryocytes treated with TPO. Conversely, platelet recovery in CIB1−/− mice after platelet depletion was attenuated compared with WT (P < .05). This could be the result of impaired adhesion and migration, as adhesion to fibrinogen and fibronectin and migration toward an SDF-1α gradient were reduced in CIB1−/− megakaryocytes compared with WT (P < .05). In addition, CIB1−/− megakaryocytes formed fewer proplatelets compared with WT (P < .05), when plated on fibrinogen. These data suggest that CIB1 plays a dual role in megakaryopoiesis, initially by negatively regulating TPO signaling and later by augmenting proplatelet production.
Justin L. Black - One of the best experts on this subject based on the ideXlab platform.
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CIB1 a small protein with big ambitions
The FASEB Journal, 2016Co-Authors: Tina M. Leisner, Justin L. Black, Thomas C Freeman, Leslie V PariseAbstract:Calcium- and integrin-binding protein 1 (CIB1) is a small, ubiquitously expressed protein that was first identified as an intracellular binding partner of a platelet-specific α-integrin cytoplasmic tail. Although early studies revealed a role for CIB1 in regulating platelet integrin activity, recent studies have indicated a more diverse role for CIB1 in many different cell types and processes, including calcium signaling, migration, adhesion, proliferation, and survival. Increasing evidence also points to a novel role for CIB1 in cancer and cardiovascular disease. In addition, an array of CIB1 binding partners has been identified that provide important insight into how CIB1 may regulate these processes. Some of these binding partners include the serine/threonine kinases, p21-activated kinase 1 (PAK1), apoptosis signal-regulating kinase 1 (ASK1), and polo-like kinase 3 (PLK3). Structural and mutational studies indicate that CIB1 binds most or all of its partners via a well-defined hydrophobic cleft. Althou...
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CIB1 depletion impairs cell survival and tumor growth in triple-negative breast cancer
Breast Cancer Research and Treatment, 2015Co-Authors: Justin L. Black, J. Chuck Harrell, Tina M. Leisner, Melissa J. Fellmeth, Samuel D. George, Dominik Reinhold, Nicole M. Baker, Corbin D. Jones, Charles M. Perou, Leslie V PariseAbstract:Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with generally poor prognosis and no available targeted therapies, highlighting a critical unmet need to identify and characterize novel therapeutic targets. We previously demonstrated that CIB1 is necessary for cancer cell survival and proliferation via regulation of two oncogenic signaling pathways, RAF–MEK–ERK and PI3K–AKT. Because these pathways are often upregulated in TNBC, we hypothesized that CIB1 may play a broader role in TNBC cell survival and tumor growth. Methods utilized include inducible RNAi depletion of CIB1 in vitro and in vivo, immunoblotting, clonogenic assay, flow cytometry, RNA-sequencing, bioinformatics analysis, and Kaplan–Meier survival analysis. CIB1 depletion resulted in significant cell death in 8 of 11 TNBC cell lines tested. Analysis of components related to PI3K–AKT and RAF–MEK–ERK signaling revealed that elevated AKT activation status and low PTEN expression were key predictors of sensitivity to CIB1 depletion. Furthermore, CIB1 knockdown caused dramatic shrinkage of MDA-MB-468 xenograft tumors in vivo. RNA sequence analysis also showed that CIB1 depletion in TNBC cells activates gene programs associated with decreased proliferation and increased cell death. CIB1 expression levels per se did not predict TNBC susceptibility to CIB1 depletion, and CIB1 mRNA expression levels did not associate with TNBC patient survival. Our data are consistent with the emerging concept of non-oncogene addiction, where a large subset of TNBCs depend on CIB1 for cell survival and tumor growth, independent of CIB1 expression levels. Our data establish CIB1 as a novel therapeutic target for TNBC.
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protein protein interactions between CIB1 and novel integrin binding partners structural and thermodynamic basis of CIB1 promiscuity 979 5
The FASEB Journal, 2014Co-Authors: Tom C Freeman, Nikolay V. Dokholyan, Justin L. Black, Tina M. Leisner, Holly G Bray, Onur Dagliyan, Yi I Wu, Ashutosh Tripathy, Leslie V PariseAbstract:The cytoplasmic protein CIB1 (calcium-and-integrin-binding protein 1) has been shown to promote cancer cell growth by affecting the RAS/RAF/MEK/ERK and the PI3K/AKT pathways, and was previously ide...
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identification of novel integrin binding partners for calcium and integrin binding protein 1 CIB1 structural and thermodynamic basis of CIB1 promiscuity
Biochemistry, 2013Co-Authors: Thomas C Freeman, Nikolay V. Dokholyan, Justin L. Black, Tina M. Leisner, Holly G Bray, Onur Dagliyan, Yi I Wu, Ashutosh Tripathy, Leslie V PariseAbstract:The short cytoplasmic tails of the α- and β-chains of integrin adhesion receptors regulate integrin activation and cell signaling. Significantly less is known about proteins that bind to α-integrin cytoplasmic tails (CTs) as opposed to β-CTs to regulate integrins. Calcium and integrin binding protein 1 (CIB1) was previously identified as an αIIb binding partner that inhibits agonist-induced activation of the platelet-specific integrin, αIIbβ3. A sequence alignment of all α-integrin CTs revealed that key residues in the CIB1 binding site of αIIb are well-conserved, and was used to delineate a consensus binding site (I/L-x-x-x-L/M-W/Y-K-x-G-F-F). Because the CIB1 binding site of αIIb is conserved in all α-integrins and CIB1 expression is ubiquitous, we asked if CIB1 could interact with other α-integrin CTs. We predicted that multiple α-integrin CTs were capable of binding to the same hydrophobic binding pocket on CIB1 with docking models generated by all-atom replica exchange discrete molecular dynamics. Af...
Kate E. Jarman - One of the best experts on this subject based on the ideXlab platform.
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CIB2 Negatively Regulates Oncogenic Signaling in Ovarian Cancer via Sphingosine Kinase 1.
Cancer Research, 2017Co-Authors: Kate E. Jarman, Noor A. Lokman, Heidi A. Neubauer, Lorena T. Davies, Briony L. Gliddon, Houng Taing, Paul A.b. Moretti, Martin K. Oehler, Melissa R. PitmanAbstract:Sphingosine kinase 1 (SK1) is a key regulator of the cellular balance between proapoptotic and prosurvival sphingolipids. Oncogenic signaling by SK1 relies on its localization to the plasma membrane, which is mediated by the calcium and integrin binding protein CIB1 via its Ca 2+ -myristoyl switch function. Here we show that another member of the CIB family, CIB2, plays a surprisingly opposite role to CIB1 in the regulation of SK1 signaling. CIB2 bound SK1 on the same site as CIB1, yet it lacks the Ca 2+ -myristoyl switch function. As a result, CIB2 blocked translocation of SK1 to the plasma membrane and inhibited its subsequent signaling, which included sensitization to TNFα-induced apoptosis and inhibition of Ras-induced neoplastic transformation. CIB2 was significantly downregulated in ovarian cancer and low CIB2 expression was associated with poor prognosis in ovarian cancer patients. Notably, reintroduction of CIB2 in ovarian cancer cells blocked plasma membrane localization of endogenous SK1, reduced in vitro neoplastic growth and tumor growth in mice, and suppressed cell motility and invasiveness both in vitro and in vivo . Consistent with the in vitro synergistic effects between the SK1-specific inhibitor SK1-I and standard chemotherapeutics, expression of CIB2 also sensitized ovarian cancer cells to carboplatin. Together, these findings identify CIB2 as a novel endogenous suppressor of SK1 signaling and potential prognostic marker and demonstrate the therapeutic potential of SK1 in this gynecologic malignancy. Cancer Res; 77(18); 4823–34. ©2017 AACR .
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CIB1 contributes to oncogenic signalling by ras via modulating the subcellular localisation of sphingosine kinase 1
Oncogene, 2017Co-Authors: Briony L. Gliddon, Leslie V Parise, Kate E. Jarman, Paul A.b. Moretti, J M Woodcock, J A Powell, A Ruszkiewicz, Melissa R. PitmanAbstract:CIB1 contributes to oncogenic signalling by Ras via modulating the subcellular localisation of sphingosine kinase 1
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translocation of sphingosine kinase 1 to the plasma membrane is mediated by calcium and integrin binding protein 1
Journal of Biological Chemistry, 2010Co-Authors: Kate E. Jarman, Paul A.b. Moretti, Julia R Zebol, Stuart M PitsonAbstract:SK1 (sphingosine kinase 1) plays an important role in many aspects of cellular regulation. Most notably, elevated cellular SK1 activity leads to increased cell proliferation, protection from apoptosis, and induction of neoplastic transformation. We have previously shown that translocation of SK1 from the cytoplasm to the plasma membrane is integral for oncogenesis mediated by this enzyme. The molecular mechanism mediating this translocation of SK1 has remained undefined. Here, we demonstrate a direct role for CIB1 (calcium and integrin-binding protein 1) in this process. We show that CIB1 interacts with SK1 in a Ca2+-dependent manner at the previously identified “calmodulin-binding site” of SK1. We also demonstrate that CIB1 functions as a Ca2+-myristoyl switch, providing a mechanism whereby it translocates SK1 to the plasma membrane. Both small interfering RNA knockdown of CIB1 and the use of a dominant-negative CIB1 we have generated prevent the agonist-dependent translocation of SK1. Furthermore, we demonstrate the requirement of CIB1-mediated translocation of SK1 in controlling cellular sphingosine 1-phosphate generation and associated anti-apoptotic signaling.