1
|
Hodapp SJ, Gravel N, Kannan N, Newton AC. Cancer-associated mutations in protein kinase C theta are loss-of-function. Biochem J 2024; 481:759-775. [PMID: 38752473 DOI: 10.1042/bcj20240148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/14/2024] [Accepted: 05/16/2024] [Indexed: 06/11/2024]
Abstract
The Ca2+-independent, but diacylglycerol-regulated, novel protein kinase C (PKC) theta (θ) is highly expressed in hematopoietic cells where it participates in immune signaling and platelet function. Mounting evidence suggests that PKCθ may be involved in cancer, particularly blood cancers, breast cancer, and gastrointestinal stromal tumors, yet how to target this kinase (as an oncogene or as a tumor suppressor) has not been established. Here, we examine the effect of four cancer-associated mutations, R145H/C in the autoinhibitory pseudosubstrate, E161K in the regulatory C1A domain, and R635W in the regulatory C-terminal tail, on the cellular activity and stability of PKCθ. Live-cell imaging studies using the genetically-encoded fluorescence resonance energy transfer-based reporter for PKC activity, C kinase activity reporter 2 (CKAR2), revealed that the pseudosubstrate and C1A domain mutations impaired autoinhibition to increase basal signaling. This impaired autoinhibition resulted in decreased stability of the protein, consistent with the well-characterized behavior of Ca2+-regulated PKC isozymes wherein mutations that impair autoinhibition are paradoxically loss-of-function because the mutant protein is degraded. In marked contrast, the C-terminal tail mutation resulted in enhanced autoinhibition and enhanced stability. Thus, the examined mutations were loss-of-function by different mechanisms: mutations that impaired autoinhibition promoted the degradation of PKC, and those that enhanced autoinhibition stabilized an inactive PKC. Supporting a general loss-of-function of PKCθ in cancer, bioinformatics analysis revealed that protein levels of PKCθ are reduced in diverse cancers, including lung, renal, head and neck, and pancreatic. Our results reveal that PKCθ function is lost in cancer.
Collapse
Affiliation(s)
- Stefanie J Hodapp
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, U.S.A
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, U.S.A
| | - Nathan Gravel
- Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, University of Georgia, Athens, GA 30602, U.S.A
| | - Natarajan Kannan
- Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, University of Georgia, Athens, GA 30602, U.S.A
| | - Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, U.S.A
| |
Collapse
|
2
|
Chen XR, Dixit K, Yang Y, McDermott MI, Imam HT, Bankaitis VA, Igumenova TI. A novel bivalent interaction mode underlies a non-catalytic mechanism for Pin1-mediated protein kinase C regulation. eLife 2024; 13:e92884. [PMID: 38687676 PMCID: PMC11060717 DOI: 10.7554/elife.92884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 04/08/2024] [Indexed: 05/02/2024] Open
Abstract
Regulated hydrolysis of the phosphoinositide phosphatidylinositol(4,5)-bis-phosphate to diacylglycerol and inositol-1,4,5-P3 defines a major eukaryotic pathway for translation of extracellular cues to intracellular signaling circuits. Members of the lipid-activated protein kinase C isoenzyme family (PKCs) play central roles in this signaling circuit. One of the regulatory mechanisms employed to downregulate stimulated PKC activity is via a proteasome-dependent degradation pathway that is potentiated by peptidyl-prolyl isomerase Pin1. Here, we show that contrary to prevailing models, Pin1 does not regulate conventional PKC isoforms α and βII via a canonical cis-trans isomerization of the peptidyl-prolyl bond. Rather, Pin1 acts as a PKC binding partner that controls PKC activity via sequestration of the C-terminal tail of the kinase. The high-resolution structure of full-length Pin1 complexed to the C-terminal tail of PKCβII reveals that a novel bivalent interaction mode underlies the non-catalytic mode of Pin1 action. Specifically, Pin1 adopts a conformation in which it uses the WW and PPIase domains to engage two conserved phosphorylated PKC motifs, the turn motif and hydrophobic motif, respectively. Hydrophobic motif is a non-canonical Pin1-interacting element. The structural information combined with the results of extensive binding studies and experiments in cultured cells suggest that non-catalytic mechanisms represent unappreciated modes of Pin1-mediated regulation of AGC kinases and other key enzymes/substrates.
Collapse
Affiliation(s)
- Xiao-Ru Chen
- Department of Biochemistry & Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Karuna Dixit
- Department of Biochemistry & Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Yuan Yang
- Department of Biochemistry & Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Mark I McDermott
- Department of Cell Biology & Genetics, Texas A&M UniversityCollege StationUnited States
| | - Hasan Tanvir Imam
- Department of Biochemistry & Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Vytas A Bankaitis
- Department of Cell Biology & Genetics, Texas A&M UniversityCollege StationUnited States
| | - Tatyana I Igumenova
- Department of Biochemistry & Biophysics, Texas A&M UniversityCollege StationUnited States
- Department of Cell Biology & Genetics, Texas A&M UniversityCollege StationUnited States
| |
Collapse
|
3
|
Chen XR, Dixit K, Yang Y, McDermott MI, Imam HT, Bankaitis VA, Igumenova TI. A novel bivalent interaction mode underlies a non-catalytic mechanism for Pin1-mediated Protein Kinase C regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.18.558341. [PMID: 37781616 PMCID: PMC10541119 DOI: 10.1101/2023.09.18.558341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Regulated hydrolysis of the phosphoinositide phosphatidylinositol(4,5)-bis-phosphate to diacylglycerol and inositol-1,4,5-P3 defines a major eukaryotic pathway for translation of extracellular cues to intracellular signaling circuits. Members of the lipid-activated protein kinase C isoenzyme family (PKCs) play central roles in this signaling circuit. One of the regulatory mechanisms employed to downregulate stimulated PKC activity is via a proteasome-dependent degradation pathway that is potentiated by peptidyl-prolyl isomerase Pin1. Here, we show that contrary to prevailing models, Pin1 does not regulate conventional PKC isoforms α and βII via a canonical cis-trans isomerization of the peptidyl-prolyl bond. Rather, Pin1 acts as a PKC binding partner that controls PKC activity via sequestration of the C-terminal tail of the kinase. The high-resolution structure of Pin1 complexed to the C-terminal tail of PKCβII reveals that a novel bivalent interaction mode underlies the non-catalytic mode of Pin1 action. Specifically, Pin1 adopts a compact conformation in which it engages two conserved phosphorylated PKC motifs, the turn motif and hydrophobic motif, the latter being a non-canonical Pin1-interacting element. The structural information, combined with the results of extensive binding studies and in vivo experiments suggest that non-catalytic mechanisms represent unappreciated modes of Pin1-mediated regulation of AGC kinases and other key enzymes/substrates.
Collapse
|
4
|
Jones AC, Kornev AP, Weng JH, Manning G, Taylor SS, Newton AC. Single-residue mutation in protein kinase C toggles between cancer and neurodegeneration. Biochem J 2023; 480:1299-1316. [PMID: 37551632 PMCID: PMC10586763 DOI: 10.1042/bcj20220397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/09/2023]
Abstract
Conventional protein kinase C (cPKC) isozymes tune the signaling output of cells, with loss-of-function somatic mutations associated with cancer and gain-of-function germline mutations identified in neurodegeneration. PKC with impaired autoinhibition is removed from the cell by quality-control mechanisms to prevent the accumulation of aberrantly active enzyme. Here, we examine how a highly conserved residue in the C1A domain of cPKC isozymes permits quality-control degradation when mutated to histidine in cancer (PKCβ-R42H) and blocks down-regulation when mutated to proline in the neurodegenerative disease spinocerebellar ataxia (PKCγ-R41P). Using FRET-based biosensors, we determined that mutation of R42 to any residue, including lysine, resulted in reduced autoinhibition as indicated by higher basal activity and faster agonist-induced plasma membrane translocation. R42 is predicted to form a stabilizing salt bridge with E655 in the C-tail and mutation of E655, but not neighboring E657, also reduced autoinhibition. Western blot analysis revealed that whereas R42H had reduced stability, the R42P mutant was stable and insensitive to activator-induced ubiquitination and down-regulation, an effect previously observed by deletion of the entire C1A domain. Molecular dynamics (MD) simulations and analysis of stable regions of the domain using local spatial pattern (LSP) alignment suggested that P42 interacts with Q66 to impair mobility and conformation of one of the ligand-binding loops. Additional mutation of Q66 to the smaller asparagine (R42P/Q66N), to remove conformational constraints, restored degradation sensitivity. Our results unveil how disease-associated mutations of the same residue in the C1A domain can toggle between gain- or loss-of-function of PKC.
Collapse
Affiliation(s)
- Alexander C. Jones
- Department of Pharmacology, University of California, La Jolla, CA 92093, U.S.A
- Biomedical Sciences Graduate Program, University of California, La Jolla, CA 92093, U.S.A
| | - Alexandr P. Kornev
- Department of Pharmacology, University of California, La Jolla, CA 92093, U.S.A
| | - Jui-Hung Weng
- Department of Pharmacology, University of California, La Jolla, CA 92093, U.S.A
| | | | - Susan S. Taylor
- Department of Pharmacology, University of California, La Jolla, CA 92093, U.S.A
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, La Jolla, CA 92093, U.S.A
| |
Collapse
|
5
|
Cao L, Chen S, Sun R, Ashby CR, Wei L, Huang Z, Chen ZS. Darovasertib, a novel treatment for metastatic uveal melanoma. Front Pharmacol 2023; 14:1232787. [PMID: 37576814 PMCID: PMC10419210 DOI: 10.3389/fphar.2023.1232787] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 07/12/2023] [Indexed: 08/15/2023] Open
Abstract
The FDA granted orphan drug designation to darovasertib, a first-in-class oral, small molecular inhibitor of protein kinase C (PKC), for the treatment of uveal melanoma, on 2 May 2022. Primary uveal melanoma has a high risk of progressing to metastatic uveal melanoma, with a poor prognosis. The activation of the PKC and mitogen-activated protein kinase pathways play an essential role in the pathogenesis of uveal melanoma, and mutations in the G protein subunit alpha q (GNAQ), and G protein subunit alpha11 (GNA11) genes are considered early events in the development of uveal melanoma. Compared to other PKC inhibitors, such as sotrastaurin and enzastaurin, darovasertib is significantly more potent in inhibiting conventional (α, β) and novel (δ, ϵ, η, θ) PKC proteins and has a better tolerability and safety profile. Current Phase I/II clinical trials indicated that darovasertib, combined with the Mitogen-activated protein kinase/Extracellular (MEK) inhibitors, binimetinib or crizotinib, produced a synergistic effect of uveal melanoma. In this article, we summarize the development of drugs for treating uveal melanomas and discuss problems associated with current treatments. We also discuss the mechanism of action, pharmacokinetic profile, adverse effects, and clinical trial for darovasertib, and future research directions for treating uveal melanoma.
Collapse
Affiliation(s)
- Lei Cao
- Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Shuzhen Chen
- School of Pharmacy, Weifang Medical University, Weifang, China
| | - Rainie Sun
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, New York, NY, United States
- Stuyvesant High School, New York, NY, United States
| | - Charles R Ashby
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, New York, NY, United States
| | - Liuya Wei
- School of Pharmacy, Weifang Medical University, Weifang, China
| | - Zoufang Huang
- Ganzhou Key Laboratory of Hematology, Department of Hematology, The First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, China
| | - Zhe-Sheng Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, New York, NY, United States
| |
Collapse
|
6
|
Xia X, Pi W, Chen M, Wang W, Cai D, Wang X, Lan Y, Yang H. Emerging roles of PHLPP phosphatases in lung cancer. Front Oncol 2023; 13:1216131. [PMID: 37576883 PMCID: PMC10414793 DOI: 10.3389/fonc.2023.1216131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/12/2023] [Indexed: 08/15/2023] Open
Abstract
Pleckstrin homologous domain leucine-rich repeating protein phosphatases (PHLPPs) were originally identified as protein kinase B (Akt) kinase hydrophobic motif specific phosphatases to maintain the cellular homeostasis. With the continuous expansion of PHLPPs research, imbalanced-PHLPPs were mainly found as a tumor suppressor gene of a variety of solid tumors. In this review, we simply described the history and structures of PHLPPs and summarized the recent achievements in emerging roles of PHLPPs in lung cancer by 1) the signaling pathways affected by PHLPPs including Phosphoinositide 3-kinase (PI3K)/AKT, RAS/RAF/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) and Protein kinase C (PKC) signaling cascades. 2) function of PHLPPs regulatory factor USP46 and miR-190/miR-215, 3) the potential roles of PHLPPs in disease prognosis, Epidermal growth factor receptors (EGFR)- tyrosine kinase inhibitor (TKI) resistance and DNA damage, 4) and the possible function of PHLPPs in radiotherapy, ferroptosis and inflammation response. Therefore, PHLPPs can be considered as either biomarker or prognostic marker for lung cancer treatment.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Haihua Yang
- Key Laboratory of Radiation Oncology of Taizhou, Radiation Oncology Institute of Enze Medical Health Academy, Department of Radiation Oncology, Taizhou Hospital Affiliated to Wenzhou Medical University, Taizhou, Zhejiang, China
| |
Collapse
|
7
|
Aquino A, Bianchi N, Terrazzan A, Franzese O. Protein Kinase C at the Crossroad of Mutations, Cancer, Targeted Therapy and Immune Response. BIOLOGY 2023; 12:1047. [PMID: 37626933 PMCID: PMC10451643 DOI: 10.3390/biology12081047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023]
Abstract
The frequent PKC dysregulations observed in many tumors have made these enzymes natural targets for anticancer applications. Nevertheless, this considerable interest in the development of PKC modulators has not led to the expected therapeutic benefits, likely due to the complex biological activities regulated by PKC isoenzymes, often playing ambiguous and protective functions, further driven by the occurrence of mutations. The structure, regulation and functions of PKCs have been extensively covered in other publications. Herein, we focused on PKC alterations mostly associated with complete functional loss. We also addressed the modest yet encouraging results obtained targeting PKC in selected malignancies and the more frequent negative clinical outcomes. The reported observations advocate the need for more selective molecules and a better understanding of the involved pathways. Furthermore, we underlined the most relevant immune mechanisms controlled by PKC isoforms potentially impacting the immune checkpoint inhibitor blockade-mediated immune recovery. We believe that a comprehensive examination of the molecular features of the tumor microenvironment might improve clinical outcomes by tailoring PKC modulation. This approach can be further supported by the identification of potential response biomarkers, which may indicate patients who may benefit from the manipulation of distinctive PKC isoforms.
Collapse
Affiliation(s)
- Angelo Aquino
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Nicoletta Bianchi
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (N.B.); (A.T.)
| | - Anna Terrazzan
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (N.B.); (A.T.)
- Laboratory for Advanced Therapy Technologies (LTTA), University of Ferrara, 44121 Ferrara, Italy
| | - Ornella Franzese
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy;
| |
Collapse
|
8
|
Abid F, Khan K, Badshah Y, Ashraf NM, Shabbir M, Hamid A, Afsar T, Almajwal A, Razak S. Non-synonymous SNPs variants of PRKCG and its association with oncogenes predispose to hepatocellular carcinoma. Cancer Cell Int 2023; 23:123. [PMID: 37344815 PMCID: PMC10286404 DOI: 10.1186/s12935-023-02965-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/07/2023] [Indexed: 06/23/2023] Open
Abstract
BACKGROUND PRKCG encodes PKC γ, which is categorized under the classical protein kinase C family. No studies have specifically established the relationship between PRKCG nsSNPs with structural and functional variations in PKC γ in the context of hepatocellular carcinoma (HCC). The present study aims to uncover this link through in-silico and experimental studies. METHODS The 3D structure of PKC γ was predicted. Molecular Dynamic (MD) Simulations were run and estimates were made for interactions, stability, conservation and post-translational alterations between wild and mutant structures. The association of PRKCG levels with HCC survival rate was determined. Genotyping analyses were conducted to investigate the deleterious PRKCG nsSNP association with HCC. mRNA expression of PKC γ, HIF-1 alpha, AKT, SOCS3 and VEGF in the blood of controls and HCC patients was analyzed and a genetic cascade was constructed depicting these interactions. RESULTS The expression level of studied oncogenes was compared to tumour suppressor genes. Through Alphafold, the 3D structure of PKC γ was explored. Fifteen SNPs were narrowed down for in-silico analyses that were identified in exons 5, 10 and 18 and the regulatory and kinase domain of PKC γ. Root mean square deviation and fluctuation along with the radius of gyration unveiled potential changes between the wild and mutated variant structures. Mutant genotype AA (homozygous) corresponding to nsSNP, rs386134171 had more frequency in patients with OR (2.446), RR (1.564) and P-values (< 0.0029) that highlights its significant association with HCC compared to controls in which the wild genotype GG was found more prevalent. CONCLUSION nsSNP rs386134171 can be a genetic marker for HCC diagnosis and therapeutic studies. This study has laid down a road map for future studies to be conducted on HCC.
Collapse
Affiliation(s)
- Fizzah Abid
- Department of Healthcare Biotechnology, Atta-Ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, 44010, Pakistan
| | - Khushbukhat Khan
- Department of Healthcare Biotechnology, Atta-Ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, 44010, Pakistan
| | - Yasmin Badshah
- Department of Healthcare Biotechnology, Atta-Ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, 44010, Pakistan
| | - Naeem Mahmood Ashraf
- School of Biochemistry and Biotechnology, University of the Punjab, Lahore, 54590, Pakistan
| | - Maria Shabbir
- Department of Healthcare Biotechnology, Atta-Ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, 44010, Pakistan.
| | - Arslan Hamid
- LIMES Institute (AG-Netea), University of Bonn, Carl-Troll-Str. 31, 53115, Bonn, Germany
| | - Tayyaba Afsar
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ali Almajwal
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Suhail Razak
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
| |
Collapse
|
9
|
Li Q, Feng T, Zhu T, Zhang W, Qian Y, Zhang H, Zheng X, Li D, Yun X, Zhao J, Li Y, Yu H, Gao M, Qian B. Multi-omics profiling of papillary thyroid microcarcinoma reveals different somatic mutations and a unique transcriptomic signature. J Transl Med 2023; 21:206. [PMID: 36941725 PMCID: PMC10026500 DOI: 10.1186/s12967-023-04045-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/08/2023] [Indexed: 03/22/2023] Open
Abstract
BACKGROUND Papillary thyroid microcarcinoma (PTMC) incidence has significantly increased, and some cases still exhibit invasive traits. The entire molecular landscape of PTMC, which can offer hints for the etiology of cancer, is currently absent. METHODS We compared our findings with those for PTMC in the TCGA by analyzing the largest study at the current stage of whole exome sequencing and RNA-sequencing data from 64 patients with PTMC. Then, we systematically demonstrated the differences between the two PTMC subtypes based on multi-omics analyses. Additionally, we created a molecular prediction model for the PTMC subtypes and validated them among TCGA patients for individualized integrative assessment. RESULTS In addition to the presence of BRAF mutations and RET fusions in the TCGA cohort, we also discovered a new molecular signature named PTMC-inflammatory that implies a potential response to immune intervention, which is enriched with AFP mutations, IGH@-ext fusions, elevated immune-related genes, positive peroxidase antibody, and positive thyroglobulin antibody. Additionally, a molecular prediction model for the PTMC-inflammatory patients was created and validated among TCGA patients, while the prognosis for these patients is poor. CONCLUSIONS Our findings comprehensively define the clinical and molecular features of PTMC and may inspire new therapeutic hypotheses.
Collapse
Affiliation(s)
- Qiang Li
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and School of Public Health, Shanghai Jiao Tong University School of Medicine, 277 South Chongqing Road, Huangpu District, Shanghai, 200025, China
| | - Tienan Feng
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and School of Public Health, Shanghai Jiao Tong University School of Medicine, 277 South Chongqing Road, Huangpu District, Shanghai, 200025, China
- Clinical Research Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Tengteng Zhu
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and School of Public Health, Shanghai Jiao Tong University School of Medicine, 277 South Chongqing Road, Huangpu District, Shanghai, 200025, China
- Clinical Research Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Weituo Zhang
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and School of Public Health, Shanghai Jiao Tong University School of Medicine, 277 South Chongqing Road, Huangpu District, Shanghai, 200025, China
| | - Ying Qian
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and School of Public Health, Shanghai Jiao Tong University School of Medicine, 277 South Chongqing Road, Huangpu District, Shanghai, 200025, China
| | - Huan Zhang
- Cancer Prevention Center, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300060, China
| | - Xiangqian Zheng
- Cancer Prevention Center, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300060, China
| | - Dapeng Li
- Cancer Prevention Center, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300060, China
| | - Xinwei Yun
- Cancer Prevention Center, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300060, China
| | - Jingzhu Zhao
- Cancer Prevention Center, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300060, China
| | - Yangyang Li
- Clinical Research Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Herbert Yu
- Cancer Epidemiology Program, University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, HI, 96813, USA
| | - Ming Gao
- Department of Thyroid and Breast Surgery, Tianjin Union Medical Center, Tianjin, Tianjin Key Laboratory of General Surgery in Construction, Tianjin Union Medical Center, Tianjin, 300121, China.
- Department of Head and Neck Tumor, Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300060, China.
| | - Biyun Qian
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and School of Public Health, Shanghai Jiao Tong University School of Medicine, 277 South Chongqing Road, Huangpu District, Shanghai, 200025, China.
- Shanghai Tenth People's Hospital Affiliated to Tongji University, Shanghai, 200072, China.
| |
Collapse
|
10
|
Jones AC, Kornev AP, Weng JH, Manning G, Taylor SS, Newton AC. Single-residue mutation in protein kinase C toggles between cancer and neurodegeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.16.532226. [PMID: 36993163 PMCID: PMC10055082 DOI: 10.1101/2023.03.16.532226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Conventional protein kinase C (PKC) isozymes tune the signaling output of cells, with loss-of-function somatic mutations associated with cancer and gain-of-function germline mutations identified in neurodegeneration. PKC with impaired autoinhibition is removed from the cell by quality-control mechanisms to prevent accumulation of aberrantly active enzyme. Here, we examine how a single residue in the C1A domain of PKCβ, arginine 42 (R42), permits quality-control degradation when mutated to histidine in cancer (R42H) and blocks downregulation when mutated to proline in the neurodegenerative disease spinocerebellar ataxia (R42P). Using FRET-based biosensors, we determined that mutation of R42 to any residue, including lysine, resulted in reduced autoinhibition as indicated by higher basal activity and faster agonist-induced plasma membrane translocation. R42 is predicted to form a stabilizing salt bridge with E655 in the C-tail and mutation of E655, but not neighboring E657, also reduced autoinhibition. Western blot analysis revealed that whereas R42H had reduced stability, the R42P mutant was stable and insensitive to activator-induced ubiquitination and downregulation, an effect previously observed by deletion of the entire C1A domain. Molecular dynamics (MD) simulations and analysis of stable regions of the domain using local spatial pattern (LSP) alignment suggested that P42 interacts with Q66 to impair mobility and conformation of one of the ligand-binding loops. Additional mutation of Q66 to the smaller asparagine (R42P/Q66N), to remove conformational constraints, restored degradation sensitivity to that of WT. Our results unveil how disease-associated mutations of the same residue in the C1A domain can toggle between gain- or loss-of-function of PKC.
Collapse
|
11
|
Tufano M, Marrone L, D'Ambrosio C, Di Giacomo V, Urzini S, Xiao Y, Matuozzo M, Scaloni A, Romano MF, Romano S. FKBP51 plays an essential role in Akt ubiquitination that requires Hsp90 and PHLPP. Cell Death Dis 2023; 14:116. [PMID: 36781840 PMCID: PMC9925821 DOI: 10.1038/s41419-023-05629-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 02/15/2023]
Abstract
FKBP51 plays a relevant role in sustaining cancer cells, particularly melanoma. This cochaperone participates in several signaling pathways. FKBP51 forms a complex with Akt and PHLPP, which is reported to dephosphorylate Akt. Given the recent discovery of a spliced FKBP51 isoform, in this paper, we interrogate the canonical and spliced isoforms in regulation of Akt activation. We show that the TPR domain of FKBP51 mediates Akt ubiquitination at K63, which is an essential step for Akt activation. The spliced FKBP51, lacking such domain, cannot link K63-Ub residues to Akt. Unexpectedly, PHLPP silencing does not foster phosphorylation of Akt, and its overexpression even induces phosphorylation of Akt. PHLPP stabilizes levels of E3-ubiquitin ligase TRAF6 and supports K63-ubiquitination of Akt. The interactome profile of FKBP51 from melanoma cells highlights a relevant role for PHLPP in improving oncogenic hallmarks, particularly, cell proliferation.
Collapse
Affiliation(s)
- Martina Tufano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Laura Marrone
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Chiara D'Ambrosio
- Proteomics, Metabolomics and Mass Spectrometry Laboratory Institute for Animal Production Systems in Mediterranean Environments (ISPAAM), National Research Council (CNR), Piazzale Enrico Fermi 1, Portici, 80055, Naples, Italy
| | - Valeria Di Giacomo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Simona Urzini
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Yichuan Xiao
- Chinese Academy of Sciences Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Monica Matuozzo
- Proteomics, Metabolomics and Mass Spectrometry Laboratory Institute for Animal Production Systems in Mediterranean Environments (ISPAAM), National Research Council (CNR), Piazzale Enrico Fermi 1, Portici, 80055, Naples, Italy
| | - Andrea Scaloni
- Proteomics, Metabolomics and Mass Spectrometry Laboratory Institute for Animal Production Systems in Mediterranean Environments (ISPAAM), National Research Council (CNR), Piazzale Enrico Fermi 1, Portici, 80055, Naples, Italy
| | - Maria Fiammetta Romano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy.
| | - Simona Romano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy.
| |
Collapse
|
12
|
Emerging roles of PHLPP phosphatases in the nervous system. Mol Cell Neurosci 2022; 123:103789. [PMID: 36343848 DOI: 10.1016/j.mcn.2022.103789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/15/2022] [Accepted: 10/22/2022] [Indexed: 11/06/2022] Open
Abstract
It has been more than a decade since the discovery of a novel class of phosphatase, the Pleckstrin Homology (PH) domain Leucine-rich repeat Protein Phosphatases (PHLPP). Over time, they have been recognized as crucial regulators of various cellular processes, such as memory formation, cellular survival and proliferation, maintenance of circadian rhythm, and others, with any deregulation in their expression or cellular localization causing havoc in any cellular system. With the ever-growing number of downstream substrates across multiple tissue systems, a web is emerging wherein the central point is PHLPP. A slight nick in the normal signaling cascade of the two isoforms of PHLPP, namely PHLPP1 and PHLPP2, has been recently found to invoke a variety of neurological disorders including Alzheimer's disease, epileptic seizures, Parkinson's disease, and others, in the neuronal system. Improper regulation of the two isoforms has also been associated with various disease pathologies such as diabetes, cardiovascular disorders, cancer, musculoskeletal disorders, etc. In this review, we have summarized all the current knowledge about PHLPP1 (PHLPP1α and PHLPP1β) and PHLPP2 and their emerging roles in regulating various neuronal signaling pathways to pave the way for a better understanding of the complexities. This would in turn aid in providing context for the development of possible future therapeutic strategies.
Collapse
|
13
|
Enhanced activity of Alzheimer disease-associated variant of protein kinase Cα drives cognitive decline in a mouse model. Nat Commun 2022; 13:7200. [PMID: 36418293 PMCID: PMC9684486 DOI: 10.1038/s41467-022-34679-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/01/2022] [Indexed: 11/27/2022] Open
Abstract
Exquisitely tuned activity of protein kinase C (PKC) isozymes is essential to maintaining cellular homeostasis. Whereas loss-of-function mutations are generally associated with cancer, gain-of-function variants in one isozyme, PKCα, are associated with Alzheimer's disease (AD). Here we show that the enhanced activity of one variant, PKCα M489V, is sufficient to rewire the brain phosphoproteome, drive synaptic degeneration, and impair cognition in a mouse model. This variant causes a modest 30% increase in catalytic activity without altering on/off activation dynamics or stability, underscoring that enhanced catalytic activity is sufficient to drive the biochemical, cellular, and ultimately cognitive effects observed. Analysis of hippocampal neurons from PKCα M489V mice reveals enhanced amyloid-β-induced synaptic depression and reduced spine density compared to wild-type mice. Behavioral studies reveal that this mutation alone is sufficient to impair cognition, and, when coupled to a mouse model of AD, further accelerates cognitive decline. The druggability of protein kinases positions PKCα as a promising therapeutic target in AD.
Collapse
|
14
|
Kawano T, Inokuchi J, Eto M, Murata M, Kang JH. Protein Kinase C (PKC) Isozymes as Diagnostic and Prognostic Biomarkers and Therapeutic Targets for Cancer. Cancers (Basel) 2022; 14:5425. [PMID: 36358843 PMCID: PMC9658272 DOI: 10.3390/cancers14215425] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/02/2022] [Accepted: 11/02/2022] [Indexed: 08/05/2023] Open
Abstract
Protein kinase C (PKC) is a large family of calcium- and phospholipid-dependent serine/threonine kinases that consists of at least 11 isozymes. Based on their structural characteristics and mode of activation, the PKC family is classified into three subfamilies: conventional or classic (cPKCs; α, βI, βII, and γ), novel or non-classic (nPKCs; δ, ε, η, and θ), and atypical (aPKCs; ζ, ι, and λ) (PKCλ is the mouse homolog of PKCι) PKC isozymes. PKC isozymes play important roles in proliferation, differentiation, survival, migration, invasion, apoptosis, and anticancer drug resistance in cancer cells. Several studies have shown a positive relationship between PKC isozymes and poor disease-free survival, poor survival following anticancer drug treatment, and increased recurrence. Furthermore, a higher level of PKC activation has been reported in cancer tissues compared to that in normal tissues. These data suggest that PKC isozymes represent potential diagnostic and prognostic biomarkers and therapeutic targets for cancer. This review summarizes the current knowledge and discusses the potential of PKC isozymes as biomarkers in the diagnosis, prognosis, and treatment of cancers.
Collapse
Affiliation(s)
- Takahito Kawano
- Center for Advanced Medical Innovation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Junichi Inokuchi
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masatoshi Eto
- Center for Advanced Medical Innovation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masaharu Murata
- Center for Advanced Medical Innovation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Jeong-Hun Kang
- Division of Biopharmaceutics and Pharmacokinetics, National Cerebral and Cardiovascular Center Research Institute, 6-1 Shinmachi, Kishibe, Suita, Osaka 564-8565, Japan
| |
Collapse
|
15
|
Lobert VH, Skardal ML, Malerød L, Simensen JE, Algra HA, Andersen AN, Fleischer T, Enserink HA, Liestøl K, Heath JK, Rusten TE, Stenmark HA. PHLPP1 regulates CFTR activity and lumen expansion through AMPK. Development 2022; 149:276412. [PMID: 35997536 PMCID: PMC9534488 DOI: 10.1242/dev.200955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/12/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Complex organ development depends on single lumen formation and its expansion during tubulogenesis. This can be achieved by correct mitotic spindle orientation during cell division, combined with luminal fluid filling that generates hydrostatic pressure. Using a human 3D cell culture model, we have identified two regulators of these processes. We find that pleckstrin homology leucine-rich repeat protein phosphatase (PHLPP) 2 regulates mitotic spindle orientation, and thereby midbody positioning and maintenance of a single lumen. Silencing the sole PHLPP family phosphatase in Drosophila melanogaster, phlpp, resulted in defective spindle orientation in Drosophila neuroblasts. Importantly, cystic fibrosis transmembrane conductance regulator (CFTR) is the main channel regulating fluid transport in this system, stimulated by phosphorylation by protein kinase A and inhibited by the AMP-activated protein kinase AMPK. During lumen expansion, CFTR remains open through the action of PHLPP1, which stops activated AMPK from inhibiting ion transport through CFTR. In the absence of PHLPP1, the restraint on AMPK activity is lost and this tips the balance in the favour of channel closing, resulting in the lack of lumen expansion and accumulation of mucus.
Collapse
Affiliation(s)
- Viola H. Lobert
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Maren L. Skardal
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Lene Malerød
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Julia E. Simensen
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Hermine A. Algra
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Aram N. Andersen
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Thomas Fleischer
- Institute for Cancer Research, Oslo University Hospital 3 Department of Cancer Genetics , , Montebello, Oslo 0379 , Norway
| | - Hilde A. Enserink
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Knut Liestøl
- University of Oslo 4 Department of Informatics , , Oslo 0316 , Norway
| | - Joan K. Heath
- Walter and Eliza Hall Institute of Medical Research 5 Epigenetics and Development Division , , Parkville, Victoria 3052 , Australia
| | - Tor Erik Rusten
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| | - Harald A. Stenmark
- Institute for Cancer Research, Oslo University Hospital 1 Department of Molecular Cell Biology , , Montebello, Oslo 0379 , Norway
- Centre for Cancer Cell Reprogramming 2 , Faculty of Medicine , , Oslo 0379 , Norway
- University of Oslo 2 , Faculty of Medicine , , Oslo 0379 , Norway
| |
Collapse
|
16
|
Pilo CA, Baffi TR, Kornev AP, Kunkel MT, Malfavon M, Chen DH, Rossitto LA, Chen DX, Huang LC, Longman C, Kannan N, Raskind WH, Gonzalez DJ, Taylor SS, Gorrie G, Newton AC. Mutations in protein kinase Cγ promote spinocerebellar ataxia type 14 by impairing kinase autoinhibition. Sci Signal 2022; 15:eabk1147. [PMID: 36166510 PMCID: PMC9810342 DOI: 10.1126/scisignal.abk1147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Spinocerebellar ataxia type 14 (SCA14) is a neurodegenerative disease caused by germline variants in the diacylglycerol (DAG)/Ca2+-regulated protein kinase Cγ (PKCγ), leading to Purkinje cell degeneration and progressive cerebellar dysfunction. Most of the identified mutations cluster in the DAG-sensing C1 domains. Here, we found with a FRET-based activity reporter that SCA14-associated PKCγ mutations, including a previously undescribed variant, D115Y, enhanced the basal activity of the kinase by compromising its autoinhibition. Unlike other mutations in PKC that impair its autoinhibition but lead to its degradation, the C1 domain mutations protected PKCγ from such down-regulation. This enhanced basal signaling rewired the brain phosphoproteome, as revealed by phosphoproteomic analysis of cerebella from mice expressing a human SCA14-associated H101Y mutant PKCγ transgene. Mutations that induced a high basal activity in vitro were associated with earlier average age of onset in patients. Furthermore, the extent of disrupted autoinhibition, but not agonist-stimulated activity, correlated with disease severity. Molecular modeling indicated that almost all SCA14 variants not within the C1 domain were located at interfaces with the C1B domain, suggesting that mutations in and proximal to the C1B domain are a susceptibility for SCA14 because they uniquely enhance PKCγ basal activity while protecting the enzyme from down-regulation. These results provide insight into how PKCγ activation is modulated and how deregulation of the cerebellar phosphoproteome by SCA14-associated mutations affects disease progression.
Collapse
Affiliation(s)
- Caila A. Pilo
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
- Biomedical Sciences Graduate Program, University of California, La Jolla, CA 92037, USA
| | - Timothy R. Baffi
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Alexandr P. Kornev
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Maya T. Kunkel
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Mario Malfavon
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Dong-Hui Chen
- Department of Neurology, University of Washington Seattle, WA 98195, USA
| | - Leigh-Ana Rossitto
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
- Biomedical Sciences Graduate Program, University of California, La Jolla, CA 92037, USA
| | - Daniel X. Chen
- Department of Neurology, University of Washington Seattle, WA 98195, USA
| | - Liang-Chin Huang
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Cheryl Longman
- Queen Elizabeth University Hospital, Glasgow, Scotland G51 4TF, United Kingdom
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Wendy H. Raskind
- Department of Medicine/Medical Genetics, University of Washington Seattle, WA 98195, USA
- Department of Psychiatry and Behavioral Sciences, University of Washington Seattle, WA 98195, USA
- Mental Illness Research, Education and Clinical Center, Department of Veterans Affairs, Seattle, WA 98108, USA
| | - David J. Gonzalez
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Susan S. Taylor
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - George Gorrie
- Queen Elizabeth University Hospital, Glasgow, Scotland G51 4TF, United Kingdom
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| |
Collapse
|
17
|
Pilo CA, Newton AC. Two Sides of the Same Coin: Protein Kinase C γ in Cancer and Neurodegeneration. Front Cell Dev Biol 2022; 10:929510. [PMID: 35800893 PMCID: PMC9253466 DOI: 10.3389/fcell.2022.929510] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 12/23/2022] Open
Abstract
Protein kinase C (PKC) isozymes transduce myriad signals within the cell in response to the generation of second messengers from membrane phospholipids. The conventional isozyme PKCγ reversibly binds Ca2+ and diacylglycerol, which leads to an open, active conformation. PKCγ expression is typically restricted to neurons, but evidence for its expression in certain cancers has emerged. PKC isozymes have been labeled as oncogenes since the discovery that they bind tumor-promoting phorbol esters, however, studies of cancer-associated PKC mutations and clinical trial data showing that PKC inhibitors have worsened patient survival have reframed PKC as a tumor suppressor. Aberrant expression of PKCγ in certain cancers suggests a role outside the brain, although whether PKCγ also acts as a tumor suppressor remains to be established. On the other hand, PKCγ variants associated with spinocerebellar ataxia type 14 (SCA14), a neurodegenerative disorder characterized by Purkinje cell degeneration, enhance basal activity while preventing phorbol ester-mediated degradation. Although the basis for SCA14 Purkinje cell degeneration remains unknown, studies have revealed how altered PKCγ activity rewires cerebellar signaling to drive SCA14. Importantly, enhanced basal activity of SCA14-associated mutants inversely correlates with age of onset, supporting that enhanced PKCγ activity drives SCA14. Thus, PKCγ activity should likely be inhibited in SCA14, whereas restoring PKC activity should be the goal in cancer therapies. This review describes how PKCγ activity can be lost or gained in disease and the overarching need for a PKC structure as a powerful tool to predict the effect of PKCγ mutations in disease.
Collapse
Affiliation(s)
- Caila A. Pilo
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
- Biomedical Sciences Graduate Program, University of California, San Diego, San Diego, CA, United States
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
- *Correspondence: Alexandra C. Newton,
| |
Collapse
|
18
|
Zhou X, Mehta S, Zhang J. AktAR and Akt-STOPS: Genetically Encodable Molecular Tools to Visualize and Perturb Akt Kinase Activity at Different Subcellular Locations in Living Cells. Curr Protoc 2022; 2:e416. [PMID: 35532280 PMCID: PMC9093046 DOI: 10.1002/cpz1.416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The serine/threonine protein kinase Akt integrates diverse upstream inputs to regulate cell survival, growth, metabolism, migration, and differentiation. Mounting evidence suggests that Akt activity is differentially regulated depending on its subcellular location, which can include the plasma membrane, endomembrane, and nuclear compartment. This spatial control of Akt activity is critical for achieving signaling specificity and proper physiological functions, and deregulation of compartment-specific Akt signaling is implicated in various diseases, including cancer and diabetes. Understanding the spatial coordination of the signaling network centered around this key kinase and the underlying regulatory mechanisms requires precise tracking of Akt activity at distinct subcellular compartments within its native biological contexts. To address this challenge, new molecular tools are being developed, enabling us to directly interrogate the spatiotemporal regulation of Akt in living cells. These include, for instance, the newly developed genetically encodable fluorescent-protein-based Akt kinase activity reporter (AktAR2), which serves as a substrate surrogate of Akt kinase and translates Akt-specific phosphorylation into a quantifiable change in Förster resonance energy transfer (FRET). In addition, we developed the Akt substrate tandem occupancy peptide sponge (Akt-STOPS), which allows biochemical perturbation of subcellular Akt activity. Both molecular tools can be readily targeted to distinct subcellular localizations. Here, we describe a workflow to study Akt kinase activity at different subcellular locations in living cells. We provide a protocol for using genetically targeted AktAR2 and Akt-STOPS, along with fluorescence imaging in living NIH3T3 cells, to visualize and perturb, respectively, the activity of endogenous Akt kinase at different subcellular compartments. We further describe a protocol for using chemically inducible dimerization (CID) to control the plasma membrane-specific inhibition of Akt activity in real time. Lastly, we describe a protocol for maintaining NIH3T3 cells in culture, a cell line known to exhibit robust Akt activity. In all, this approach enables interrogation of spatiotemporal regulation and functions of Akt, as well as the intricate signaling networks in which it is embedded, at specific subcellular locations. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Visualizing and perturbing subcellular Akt kinase activity using AktAR and Akt-STOPS Basic Protocol 2: Using chemically inducible dimerization (CID) to control inhibition of Akt at the plasma membrane Support Protocol: Maintaining NIH3T3 cells in culture.
Collapse
Affiliation(s)
- Xin Zhou
- Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Sohum Mehta
- Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, California.,Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, California.,Department of Bioengineering, University of California, San Diego, La Jolla, California
| |
Collapse
|
19
|
Aslam N, Alvi F. Protein Kinase C Life Cycle: Explained Through Systems Biology Approach. Front Physiol 2022; 13:818688. [PMID: 35492590 PMCID: PMC9049586 DOI: 10.3389/fphys.2022.818688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/04/2022] [Indexed: 11/18/2022] Open
Abstract
Protein kinase C (PKC) enzymes are a family of kinases that mediate signal transduction originating at the cell surface. Most cell membranes can contain functional PKC enzymes. Aberrations in the PKC life cycle may result in cellular damage and dysfunction. For example, some cancerous cells exhibit alterations in PKC activity. Here, we use a systems biology approach to describe a molecular model of the PKC life cycle. Understanding the PKC life cycle is necessary to identify new drug targets. The PKC life cycle is composed of three key regulatory processes: maturation, activation, and termination. These processes precisely control PKC enzyme levels. This model describes the fate of PKC during de novo synthesis and PKC’s lipid-mediated activation cycle. We utilize a systems biology approach to show the PKC life cycle is controlled by multiple phosphorylation and dephosphorylation events. PKC processing events can be divided into two types: maturation via processing of newly synthesized enzyme and secondary messenger-dependent activation of dormant, but catalytically competent enzyme. Newly synthesized PKC enzyme is constitutively processed through three ordered phosphorylations and stored in the cytosol as a stable, signaling-competent inactive and autoinhibited molecule. Upon extracellular stimulation, diacylglycerol (DAG) and calcium ion (Ca2+) generated at the membrane bind PKC. PKC then undergoes cytosol-to-membrane translocation and subsequent activation. Our model shows that, once activated, PKC is prone to dephosphorylation and subsequent degradation. This model also describes the role of HSP70 in stabilization and re-phosphorylation of dephosphorylated PKC, replenishing the PKC pool. Our model shows how the PKC pool responds to different intensities of extracellular stimuli? We show that blocking PHLPP dephosphorylation replenishes the PKC pool in a dose-dependent manner. This model provides a comprehensive understanding of PKC life cycle regulation.
Collapse
Affiliation(s)
- Naveed Aslam
- BioSystOmics, Houston, TX, United States
- *Correspondence: Naveed Aslam,
| | - Farah Alvi
- BioSystOmics, Houston, TX, United States
- Department of Physics, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan
| |
Collapse
|
20
|
Baffi TR, Newton AC. Protein kinase C: release from quarantine by mTORC2. Trends Biochem Sci 2022; 47:518-530. [DOI: 10.1016/j.tibs.2022.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/14/2022] [Accepted: 03/02/2022] [Indexed: 01/31/2023]
|
21
|
PHLPP Signaling in Immune Cells. Curr Top Microbiol Immunol 2022; 436:117-143. [DOI: 10.1007/978-3-031-06566-8_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
22
|
Lordén G, Newton A. Conventional protein kinase C in the brain: repurposing cancer drugs for neurodegenerative treatment? Neuronal Signal 2021; 5:NS20210036. [PMID: 34737895 PMCID: PMC8536831 DOI: 10.1042/ns20210036] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 12/23/2022] Open
Abstract
Protein Kinase C (PKC) isozymes are tightly regulated kinases that transduce a myriad of signals from receptor-mediated hydrolysis of membrane phospholipids. They play an important role in brain physiology, and dysregulation of PKC activity is associated with neurodegeneration. Gain-of-function mutations in PKCα are associated with Alzheimer's disease (AD) and mutations in PKCγ cause spinocerebellar ataxia (SCA) type 14 (SCA14). This article presents an overview of the role of the conventional PKCα and PKCγ in neurodegeneration and proposes repurposing PKC inhibitors, which failed in clinical trials for cancer, for the treatment of neurodegenerative diseases.
Collapse
Affiliation(s)
- Gema Lordén
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, U.S.A
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, U.S.A
| |
Collapse
|
23
|
Li DK, Chen XR, Wang LN, Wang JH, Wen YT, Zhou ZY, Li JK, Liu JX, Cai LB, Zhong SS, Lyu XM, Damola FO, Li MY, Zhang JJ, Zeng YM, Wang QL, Zhang QB, Lyu H, Fu XY, Wang W, Li X, Huang ZX, Yao KT. Epstein-Barr Virus Induces Lymphangiogenesis and Lympth Node Metastasis via Upregulation of VEGF-C in Nasopharyngeal Carcinoma. Mol Cancer Res 2021; 20:161-175. [PMID: 34654722 DOI: 10.1158/1541-7786.mcr-21-0164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/21/2021] [Accepted: 09/30/2021] [Indexed: 11/16/2022]
Abstract
Lymphatic metastasis is a common clinical symptom in nasopharyngeal carcinoma (NPC), the most common Epstein-Barr virus (EBV)-associated head and neck malignancy. However, the effect of EBV on NPC lymph node (LN) metastasis is still unclear. In this study, we demonstrated that EBV infection is strongly associated with advanced clinical N stage and lymphangiogenesis of NPC. We found that NPC cells infected with EBV promote LN metastasis by inducing cancer-associated lymphangiogenesis, whereas these changes were abolished upon clearance of EBV genomes. Mechanistically, EBV-induced VEGF-C contributed to lymphangiogenesis and LN metastasis, and PHLPP1, a target of miR-BART15, partially contributed to AKT/HIF1a hyperactivity and subsequent VEGF-C transcriptional activation. In addition, administration of anti-VEGF-C antibody or HIF1α inhibitors attenuated the lymphangiogenesis and LN metastasis induced by EBV. Finally, we verified the clinical significance of this prometastatic EBV/VEGF-C axis by determining the expression of PHLPP1, AKT, HIF1a, and VEGF-C in NPC specimens with and without EBV. These results uncover a reasonable mechanism for the EBV-modulated LN metastasis microenvironment in NPC, indicating that EBV is a potential therapeutic target for NPC with lymphatic metastasis. IMPLICATIONS: This research demonstrates that EBV induces lymphangiogenesis in NPC by regulating PHLPP1/p-AKT/HIF1a/VEGF-C, providing a new therapeutic target for NPC with lymphatic metastasis.
Collapse
Affiliation(s)
- Deng-Ke Li
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Xing-Rui Chen
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Li-Na Wang
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China.,Guangzhou First People's Hospital, School of Medicine, Southern China University of Technology, Guangzhou, P.R. China
| | - Jia-Hong Wang
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Yue-Ting Wen
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Zi-Ying Zhou
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Ji-Ke Li
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Jing-Xian Liu
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Lin-Bo Cai
- Guangdong Sanjiu Brain Hospital, Guangzhou, P.R. China
| | | | - Xiao-Ming Lyu
- Department of Laboratory Medicine, The Third Affiliated Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Faleti Oluwasijibomi Damola
- Department of Laboratory Medicine, The Third Affiliated Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Min-Ying Li
- Department of Radiotherapy, Tumor Hospital of Zhongshan People's Hospital, Zhongshan, P.R. China
| | - Jing-Jing Zhang
- Department of Radiotherapy, Tumor Hospital of Zhongshan People's Hospital, Zhongshan, P.R. China
| | - Yu-Mei Zeng
- Department of Pathology, Tumor Hospital of Zhongshan People's Hospital, Zhongshan, P.R. China
| | - Qian-Li Wang
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou, P.R. China
| | - Qian-Bing Zhang
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Hao Lyu
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Xiao-Yan Fu
- Department of Otorhinolaryngology Head and Neck Surgery, General Hospital of Southern Theater Command, People's Liberation Army of China, Guangzhou, P.R. China
| | - Wei Wang
- Department of Pathology, General Hospital of Southern Theater Command, People's Liberation Army of China, Guangzhou, P.R. China
| | - Xin Li
- Shenzhen Key Laboratory of Viral Oncology, the Clinical Innovation & Research Center (CIRC), Shenzhen Hospital, Southern Medical University, Shenzhen, P.R. China.
| | - Zhong-Xi Huang
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China.
| | - Kai-Tai Yao
- Guangdong Provincial Key Laboratory of Tumor Immunotherapy, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China.
| |
Collapse
|
24
|
Lemoine KA, Fassas JM, Ohannesian SH, Purcell NH. On the PHLPPside: Emerging roles of PHLPP phosphatases in the heart. Cell Signal 2021; 86:110097. [PMID: 34320369 PMCID: PMC8403656 DOI: 10.1016/j.cellsig.2021.110097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 02/07/2023]
Abstract
PH domain leucine-rich repeat protein phosphatase (PHLPP) is a family of enzymes made up of two isoforms (PHLPP1 and PHLPP2), whose actions modulate intracellular activity via the dephosphorylation of specific serine/threonine (Ser/Thr) residues on proteins such as Akt. Recent data generated in our lab, supported by findings from others, implicates the divergent roles of PHLPP1 and PHLPP2 in maintaining cellular homeostasis since dysregulation of these enzymes has been linked to various pathological states including cardiovascular disease, diabetes, ischemia/reperfusion injury, musculoskeletal disease, and cancer. Therefore, development of therapies to modulate specific isoforms of PHLPP could prove to be therapeutically beneficial in several diseases especially those targeting the cardiovascular system. This review is intended to provide a comprehensive summary of current literature detailing the role of the PHLPP isoforms in the development and progression of heart disease.
Collapse
Affiliation(s)
- Kellie A Lemoine
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92039, USA
| | - Julianna M Fassas
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92039, USA
| | - Shirag H Ohannesian
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92039, USA
| | - Nicole H Purcell
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92039, USA; Cardiovascular Molecular Signaling, Huntington Medical Research Institutes, Pasadena, CA 91105, USA.
| |
Collapse
|
25
|
Abstract
Over the last decades, research has focused on the role of pleckstrin homology (PH) domain leucine-rich repeat protein phosphatases (PHLPPs) in regulating cellular signaling via PI3K/Akt inhibition. The PKB/Akt signaling imbalances are associated with a variety of illnesses, including various types of cancer, inflammatory response, insulin resistance, and diabetes, demonstrating the relevance of PHLPPs in the prevention of diseases. Furthermore, identification of novel substrates of PHLPPs unveils their role as a critical mediator in various cellular processes. Recently, researchers have explored the increasing complexity of signaling networks involving PHLPPs whereby relevant information of PHLPPs in metabolic diseases was obtained. In this review, we discuss the current knowledge of PHLPPs on the well-known substrates and metabolic regulation, especially in liver, pancreatic beta cell, adipose tissue, and skeletal muscle in relation with the stated diseases. Understanding the context-dependent functions of PHLPPs can lead to a promising treatment strategy for several kinds of metabolic diseases.
Collapse
Affiliation(s)
- Jong-Ho Cha
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon 22212, Korea
- Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Korea
| | - Yelin Jeong
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon 22212, Korea
- Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Korea
- Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon 22212, Korea
| | - Ah-Reum Oh
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon 22212, Korea
- Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Korea
- Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon 22212, Korea
| | - Sang Bae Lee
- Division of Life Sciences, Jeonbuk National University; Sarcopenia Total Solution Center, Jeonju 54896, Korea
| | - Soon-Sun Hong
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon 22212, Korea
- Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Korea
- Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon 22212, Korea
| | - KyeongJin Kim
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon 22212, Korea
- Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Korea
- Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon 22212, Korea
| |
Collapse
|
26
|
Baffi TR, Newton AC. mTOR Regulation of AGC Kinases: New Twist to an Old Tail. Mol Pharmacol 2021; 101:213-218. [PMID: 34155089 DOI: 10.1124/molpharm.121.000310] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/09/2021] [Indexed: 11/22/2022] Open
Abstract
The family of AGC kinases not only regulate cellular biology by phosphorylating substrates, but are themselves controlled by phosphorylation. Phosphorylation generally occurs at two conserved regions in these kinases: a loop near the entrance to the active site, termed the activation loop, that correctly aligns residues for catalysis, and a C-terminal tail whose phosphorylation at a site termed the hydrophobic motif stabilizes the active conformation. Whereas phosphorylation of the activation loop is well established to be catalyzed by the phosphoinositide-dependent kinase 1 (PDK1), the mechanism of phosphorylation of the C-tail hydrophobic motif has been controversial. For a subset of AGC kinases, which includes most protein kinase C (PKC) isozymes and Akt, phosphorylation of the hydrophobic motif in cells was shown to depend on mTORC2 over 15 years ago, yet whether by direct phosphorylation or by another mechanism has remained elusive. The recent identification of a novel and evolutionarily conserved phosphorylation site on the C-tail termed the TOR-Interaction Motif (TIM) has finally unraveled the mystery of how mTORC2 regulates its client kinases. mTORC2 does not directly phosphorylate the hydrophobic motif, rather it converts kinases such as PKC and Akt into a conformation that can ultimately autophosphorylate at the hydrophobic motif. Identification of the direct mTOR phosphorylation that facilitates auto-regulation of the C-tail hydrophobic motif revises the activation mechanisms of mTOR-regulated AGC kinases. This new twist to an old tail opens avenues for therapeutic intervention. Significance Statement The enzyme mTORC2 has been an enigmatic regulator of AGC kinases such as protein kinase C (PKC) and Akt. The recent discovery of a motif named the TOR Interaction Motif in the C-tail of these kinases solves the mystery: mTORC2 marks these kinases for maturity by, ultimately, facilitating autophosphorylation another C-tail site, the hydrophobic motif.
Collapse
|
27
|
PHLPPing the balance: restoration of protein kinase C in cancer. Biochem J 2021; 478:341-355. [PMID: 33502516 DOI: 10.1042/bcj20190765] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 12/28/2022]
Abstract
Protein kinase signalling, which transduces external messages to mediate cellular growth and metabolism, is frequently deregulated in human disease, and specifically in cancer. As such, there are 77 kinase inhibitors currently approved for the treatment of human disease by the FDA. Due to their historical association as the receptors for the tumour-promoting phorbol esters, PKC isozymes were initially targeted as oncogenes in cancer. However, a meta-analysis of clinical trials with PKC inhibitors in combination with chemotherapy revealed that these treatments were not advantageous, and instead resulted in poorer outcomes and greater adverse effects. More recent studies suggest that instead of inhibiting PKC, therapies should aim to restore PKC function in cancer: cancer-associated PKC mutations are generally loss-of-function and high PKC protein is protective in many cancers, including most notably KRAS-driven cancers. These recent findings have reframed PKC as having a tumour suppressive function. This review focusses on a potential new mechanism of restoring PKC function in cancer - through targeting of its negative regulator, the Ser/Thr protein phosphatase PHLPP. This phosphatase regulates PKC steady-state levels by regulating the phosphorylation of a key site, the hydrophobic motif, whose phosphorylation is necessary for the stability of the enzyme. We also consider whether the phosphorylation of the potent oncogene KRAS provides a mechanism by which high PKC expression may be protective in KRAS-driven human cancers.
Collapse
|
28
|
Recasens A, Humphrey SJ, Ellis M, Hoque M, Abbassi RH, Chen B, Longworth M, Needham EJ, James DE, Johns TG, Day BW, Kassiou M, Yang P, Munoz L. Global phosphoproteomics reveals DYRK1A regulates CDK1 activity in glioblastoma cells. Cell Death Discov 2021; 7:81. [PMID: 33863878 PMCID: PMC8052442 DOI: 10.1038/s41420-021-00456-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/19/2021] [Accepted: 02/03/2021] [Indexed: 12/12/2022] Open
Abstract
Both 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.
Collapse
Affiliation(s)
- Ariadna Recasens
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia.
| | - Sean J Humphrey
- Charles Perkins Centre and School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Michael Ellis
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Monira Hoque
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Ramzi H Abbassi
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Brianna Chen
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Mitchell Longworth
- School of Chemistry, Faculty of Science, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Elise J Needham
- Charles Perkins Centre and School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - David E James
- Charles Perkins Centre and School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Terrance G Johns
- Oncogenic Signalling Laboratory, Telethon Kids Institute, Perth Children's Hospital, 15 Hospital Avenue, Nedlands, WA, 6009, Australia
| | - Bryan W Day
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, QLD, 4006, Australia
| | - Michael Kassiou
- School of Chemistry, Faculty of Science, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Pengyi Yang
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia.,Charles Perkins Centre and School of Mathematics and Statistics, Faculty of Science, The University of Sydney, Sydney, NSW, 2006, Australia.,Computational Systems Biology Group, Children's Medical Research Institute, University of Sydney, Westmead, NSW, 2145, Australia
| | - Lenka Munoz
- Charles Perkins Centre and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia.
| |
Collapse
|
29
|
Baffi TR, Lordén G, Wozniak JM, Feichtner A, Yeung W, Kornev AP, King CC, Del Rio JC, Limaye AJ, Bogomolovas J, Gould CM, Chen J, Kennedy EJ, Kannan N, Gonzalez DJ, Stefan E, Taylor SS, Newton AC. mTORC2 controls the activity of PKC and Akt by phosphorylating a conserved TOR interaction motif. Sci Signal 2021; 14:eabe4509. [PMID: 33850054 PMCID: PMC8208635 DOI: 10.1126/scisignal.abe4509] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The complex mTORC2 is accepted to be the kinase that controls the phosphorylation of the hydrophobic motif, a key regulatory switch for AGC kinases, although whether mTOR directly phosphorylates this motif remains controversial. Here, we identified an mTOR-mediated phosphorylation site that we termed the TOR interaction motif (TIM; F-x3-F-pT), which controls the phosphorylation of the hydrophobic motif of PKC and Akt and the activity of these kinases. The TIM is invariant in mTORC2-dependent AGC kinases, is evolutionarily conserved, and coevolved with mTORC2 components. Mutation of this motif in Akt1 and PKCβII abolished cellular kinase activity by impairing activation loop and hydrophobic motif phosphorylation. mTORC2 directly phosphorylated the PKC TIM in vitro, and this phosphorylation event was detected in mouse brain. Overexpression of PDK1 in mTORC2-deficient cells rescued hydrophobic motif phosphorylation of PKC and Akt by a mechanism dependent on their intrinsic catalytic activity, revealing that mTORC2 facilitates the PDK1 phosphorylation step, which, in turn, enables autophosphorylation. Structural analysis revealed that PKC homodimerization is driven by a TIM-containing helix, and biophysical proximity assays showed that newly synthesized, unphosphorylated PKC dimerizes in cells. Furthermore, disruption of the dimer interface by stapled peptides promoted hydrophobic motif phosphorylation. Our data support a model in which mTORC2 relieves nascent PKC dimerization through TIM phosphorylation, recruiting PDK1 to phosphorylate the activation loop and triggering intramolecular hydrophobic motif autophosphorylation. Identification of TIM phosphorylation and its role in the regulation of PKC provides the basis for AGC kinase regulation by mTORC2.
Collapse
Affiliation(s)
- Timothy R Baffi
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Gema Lordén
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Jacob M Wozniak
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093, USA
| | - Andreas Feichtner
- Institute of Biochemistry and Center for Molecular Biosciences, University of Innsbruck, Innsbruck A-6020, Austria
| | - Wayland Yeung
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Alexandr P Kornev
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Charles C King
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Jason C Del Rio
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Ameya J Limaye
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA
| | - Julius Bogomolovas
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Christine M Gould
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Ju Chen
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Eileen J Kennedy
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - David J Gonzalez
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093, USA
| | - Eduard Stefan
- Institute of Biochemistry and Center for Molecular Biosciences, University of Innsbruck, Innsbruck A-6020, Austria
| | - Susan S Taylor
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093, USA
| | - Alexandra C Newton
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA.
| |
Collapse
|
30
|
The PHLPP1 N-Terminal Extension Is a Mitotic Cdk1 Substrate and Controls an Interactome Switch. Mol Cell Biol 2021; 41:e0033320. [PMID: 33397691 PMCID: PMC8088274 DOI: 10.1128/mcb.00333-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PH domain leucine-rich repeat protein phosphatase 1 (PHLPP1) is a tumor suppressor that directly dephosphorylates a wide array of substrates, most notably the prosurvival kinase Akt. However, little is known about the molecular mechanisms governing PHLPP1 itself. Here, we report that PHLPP1 is dynamically regulated in a cell cycle-dependent manner and deletion of PHLPP1 results in mitotic delays and increased rates of chromosomal segregation errors. We show that PHLPP1 is hyperphosphorylated during mitosis by Cdk1 in a functionally uncharacterized region known as the PHLPP1 N-terminal extension (NTE). A proximity-dependent biotin identification (BioID) interaction screen revealed that during mitosis, PHLPP1 dissociates from plasma membrane scaffolds, such as Scribble, by a mechanism that depends on its NTE and gains proximity to kinetochore and mitotic spindle proteins such as KNL1 and TPX2. Our data are consistent with a model in which phosphorylation of PHLPP1 during mitosis regulates binding to its mitotic partners and allows accurate progression through mitosis. The finding that PHLPP1 binds mitotic proteins in a cell cycle- and phosphorylation-dependent manner may have relevance to its tumor-suppressive function.
Collapse
|
31
|
A New Mouse Model Related to SCA14 Carrying a Pseudosubstrate Domain Mutation in PKCγ Shows Perturbed Purkinje Cell Maturation and Ataxic Motor Behavior. J Neurosci 2021; 41:2053-2068. [PMID: 33478986 PMCID: PMC7939089 DOI: 10.1523/jneurosci.1946-20.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 01/12/2021] [Accepted: 01/12/2021] [Indexed: 01/15/2023] Open
Abstract
Spinocerebellar ataxias (SCAs) are diseases characterized by cerebellar atrophy and loss of Purkinje neurons caused by mutations in diverse genes. In SCA14, the disease is caused by point mutations or small deletions in protein kinase C γ (PKCγ), a crucial signaling protein in Purkinje cells. It is still unclear whether increased or decreased PKCγ activity may be involved in the SCA14 pathogenesis. In this study, we present a new knock-in mouse model related to SCA14 with a point mutation in the pseudosubstrate domain, PKCγ-A24E, known to induce a constitutive PKCγ activation. In this protein conformation, the kinase domain of PKCγ is activated, but at the same time the protein is subject to dephosphorylation and protein degradation. As a result, we find a dramatic reduction of PKCγ protein expression in PKCγ-A24E mice of either sex. Despite this reduction, there is clear evidence for an increased PKC activity in Purkinje cells from PKCγ-A24E mice. Purkinje cells derived from PKCγ-A24E have short thickened dendrites typical for PKC activation. These mice also develop a marked ataxia and signs of Purkinje cell dysfunction making them an interesting new mouse model related to SCA. Recently, a similar mutation in a human patient was discovered and found to be associated with overt SCA14. RNA profiling of PKCγ-A24E mice showed a dysregulation of related signaling pathways, such as mGluR1 or mTOR. Our results show that the induction of PKCγ activation in Purkinje cells results in the SCA-like phenotype indicating PKC activation as one pathogenetic avenue leading to a SCA.SIGNIFICANCE STATEMENT Spinocerebellar ataxias (SCAs) are hereditary diseases affecting cerebellar Purkinje cells and are a one of neurodegenerative diseases. While mutation in several genes have been identified as causing SCAs, it is unclear how these mutations cause the disease phenotype. Mutations in PKCγ cause one subtype of SCAs, SCA14. In this study, we have generated a knock-in mouse with a mutation in the pseudosubstrate domain of PKCγ, which keeps PKCγ in the constitutive active open conformation. We show that this mutation leading to a constant activation of PKCγ results in a SCA-like phenotype in these mice. Our findings establish the constant activation of PKC signaling as one pathogenetic avenue leading to an SCA phenotype and a mechanism causing a neurodegenerative disease.
Collapse
|
32
|
Baffi TR, Cohen-Katsenelson K, Newton AC. PHLPPing the Script: Emerging Roles of PHLPP Phosphatases in Cell Signaling. Annu Rev Pharmacol Toxicol 2021; 61:723-743. [PMID: 32997603 PMCID: PMC11003498 DOI: 10.1146/annurev-pharmtox-031820-122108] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Whereas protein kinases have been successfully targeted for a variety of diseases, protein phosphatases remain an underutilized therapeutic target, in part because of incomplete characterization of their effects on signaling networks. The pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) is a relatively new player in the cell signaling field, and new roles in controlling the balance among cell survival, proliferation, and apoptosis are being increasingly identified. Originally characterized for its tumor-suppressive function in deactivating the prosurvival kinase Akt, PHLPP may have an opposing role in promoting survival, as recent evidence suggests. Additionally, identification of the transcription factor STAT1 as a substrate unveils a role for PHLPP as a critical mediator of transcriptional programs in cancer and the inflammatory response. This review summarizes the current knowledge of PHLPP as both a tumor suppressor and an oncogene and highlights emerging functions in regulating gene expression and the immune system. Understanding the context-dependent functions of PHLPP is essential for appropriate therapeutic intervention.
Collapse
Affiliation(s)
- Timothy R Baffi
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093-0721, USA;
| | - Ksenya Cohen-Katsenelson
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093-0721, USA;
| | - Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093-0721, USA;
| |
Collapse
|
33
|
Van AAN, Kunkel MT, Baffi TR, Lordén G, Antal CE, Banerjee S, Newton AC. Protein kinase C fusion proteins are paradoxically loss of function in cancer. J Biol Chem 2021; 296:100445. [PMID: 33617877 PMCID: PMC8008189 DOI: 10.1016/j.jbc.2021.100445] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 02/11/2021] [Accepted: 02/18/2021] [Indexed: 12/02/2022] Open
Abstract
Within the AGC kinase superfamily, gene fusions resulting from chromosomal rearrangements have been most frequently described for protein kinase C (PKC), with gene fragments encoding either the C-terminal catalytic domain or the N-terminal regulatory moiety fused to other genes. Kinase fusions that eliminate regulatory domains are typically gain of function and often oncogenic. However, several quality control pathways prevent accumulation of aberrant PKC, suggesting that PKC fusions may paradoxically be loss of function. To explore this topic, we used biochemical, cellular, and genome editing approaches to investigate the function of fusions that retain the portion of the gene encoding either the catalytic domain or regulatory domain of PKC. Overexpression studies revealed that PKC catalytic domain fusions were constitutively active but vulnerable to degradation. Genome editing of endogenous genes to generate a cancer-associated PKC fusion resulted in cells with detectable levels of fusion transcript but no detectable protein. Hence, PKC catalytic domain fusions are paradoxically loss of function as a result of their instability, preventing appreciable accumulation of protein in cells. Overexpression of a PKC regulatory domain fusion suppressed both basal and agonist-induced endogenous PKC activity, acting in a dominant-negative manner by competing for diacylglycerol. For both catalytic and regulatory domain fusions, the PKC component of the fusion proteins mediated the effects of the full-length fusions on the parameters examined, suggesting that the partner protein is dispensable in these contexts. Taken together, our findings reveal that PKC gene fusions are distinct from oncogenic fusions and present a mechanism by which loss of PKC function occurs in cancer.
Collapse
Affiliation(s)
- An-Angela N Van
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, California, USA
| | - Maya T Kunkel
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA
| | - Timothy R Baffi
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, California, USA
| | - Gema Lordén
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA
| | - Corina E Antal
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, California, USA
| | - Sourav Banerjee
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA
| | - Alexandra C Newton
- Department of Pharmacology, University of California at San Diego, La Jolla, California, USA.
| |
Collapse
|
34
|
Parker PJ, Brown SJ, Calleja V, Chakravarty P, Cobbaut M, Linch M, Marshall JJT, Martini S, McDonald NQ, Soliman T, Watson L. Equivocal, explicit and emergent actions of PKC isoforms in cancer. Nat Rev Cancer 2021; 21:51-63. [PMID: 33177705 DOI: 10.1038/s41568-020-00310-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
The maturing mutational landscape of cancer genomes, the development and application of clinical interventions and evolving insights into tumour-associated functions reveal unexpected features of the protein kinase C (PKC) family of serine/threonine protein kinases. These advances include recent work showing gain or loss-of-function mutations relating to driver or bystander roles, how conformational constraints and plasticity impact this class of proteins and how emergent cancer-associated properties may offer opportunities for intervention. The profound impact of the tumour microenvironment, reflected in the efficacy of immune checkpoint interventions, further prompts to incorporate PKC family actions and interventions in this ecosystem, informed by insights into the control of stromal and immune cell functions. Drugging PKC isoforms has offered much promise, but when and how is not obvious.
Collapse
Affiliation(s)
- Peter J Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK.
- School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Campus, London, UK.
| | - Sophie J Brown
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Veronique Calleja
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | | | - Mathias Cobbaut
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Mark Linch
- UCL Cancer Institute, University College London, London, UK
| | | | - Silvia Martini
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Neil Q McDonald
- Signalling and Structural Biology Laboratory, Francis Crick Institute, London, UK
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, UK
| | - Tanya Soliman
- Centre for Cancer Genomics and Computational Biology, Bart's Cancer Institute, London, UK
| | - Lisa Watson
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| |
Collapse
|
35
|
Zhou X, Zhong Y, Molinar-Inglis O, Kunkel MT, Chen M, Sun T, Zhang J, Shyy JYJ, Trejo J, Newton AC, Zhang J. Location-specific inhibition of Akt reveals regulation of mTORC1 activity in the nucleus. Nat Commun 2020; 11:6088. [PMID: 33257668 PMCID: PMC7705703 DOI: 10.1038/s41467-020-19937-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 10/27/2020] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates growth, nutrient and energy status cues to control cell growth and metabolism. While mTORC1 activation at the lysosome is well characterized, it is not clear how this complex is regulated at other subcellular locations. Here, we combine location-selective kinase inhibition, live-cell imaging and biochemical assays to probe the regulation of growth factor-induced mTORC1 activity in the nucleus. Using a nuclear targeted Akt Substrate-based Tandem Occupancy Peptide Sponge (Akt-STOPS) that we developed for specific inhibition of Akt, a critical upstream kinase, we show that growth factor-stimulated nuclear mTORC1 activity requires nuclear Akt activity. Further mechanistic dissection suggests that nuclear Akt activity mediates growth factor-induced nuclear translocation of Raptor, a regulatory scaffolding component in mTORC1, and localization of Raptor to the nucleus results in nuclear mTORC1 activity in the absence of growth factor stimulation. Taken together, these results reveal a mode of regulation of mTORC1 that is distinct from its lysosomal activation, which controls mTORC1 activity in the nuclear compartment.
Collapse
Affiliation(s)
- Xin Zhou
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Yanghao Zhong
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA, USA
| | | | - Maya T Kunkel
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Mingyuan Chen
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Tengqian Sun
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jiao Zhang
- Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - John Y-J Shyy
- Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - JoAnn Trejo
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA.
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
- Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, CA, USA.
| |
Collapse
|
36
|
Jones AC, Taylor SS, Newton AC, Kornev AP. Hypothesis: Unifying model of domain architecture for conventional and novel protein kinase C isozymes. IUBMB Life 2020; 72:2584-2590. [PMID: 33166426 DOI: 10.1002/iub.2401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/17/2020] [Accepted: 10/17/2020] [Indexed: 12/26/2022]
Abstract
Protein kinase C (PKC) family members are multi-domain proteins whose function is exquisitely tuned by interdomain interactions that control the spatiotemporal dynamics of their signaling. Despite extensive mechanistic studies on this family of enzymes, no structure of a full-length enzyme that includes all domains has been solved. Here, we take into account the biochemical mechanisms that control autoinhibition, the properties of each individual domain, and previous structural studies to propose a unifying model for the general architecture of PKC family members. This model shows how the C2 domains of conventional and novel PKC isozymes, which have different topologies and different positions in the primary structure, can occupy the same position in the tertiary structure of the kinase. This common architecture of conventional and novel PKC isozymes provides a framework for understanding how disease-associated mutations impair PKC function.
Collapse
Affiliation(s)
- Alexander C Jones
- Department of Pharmacology, University of California, San Diego, La Jolla, California, USA.,Biomedical Sciences Graduate Program, University of California, La Jolla, California, USA
| | - Susan S Taylor
- Department of Pharmacology, University of California, San Diego, La Jolla, California, USA
| | - Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, California, USA
| | - Alexandr P Kornev
- Department of Pharmacology, University of California, San Diego, La Jolla, California, USA
| |
Collapse
|
37
|
Borges GA, Elias ST, Amorim B, de Lima CL, Coletta RD, Castilho RM, Squarize CH, Guerra ENS. Curcumin downregulates the PI3K-AKT-mTOR pathway and inhibits growth and progression in head and neck cancer cells. Phytother Res 2020; 34:3311-3324. [PMID: 32628350 DOI: 10.1002/ptr.6780] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/05/2020] [Accepted: 05/30/2020] [Indexed: 12/15/2022]
Abstract
Curcumin, a polyphenol isolated from the rhizome of Curcuma longa, has been studied because of its antioxidant, antimicrobial, and antiinflammatory properties. This study aimed to evaluate the effects of curcumin on head and neck cancer (HNC) cell lines and how it modulates the PI3K-AKT-mTOR signaling pathway. Dose-response curves for curcumin were established for hypopharynx carcinoma (FaDu), tongue carcinoma (SCC-9), and keratinocytes (HaCaT) cell lines and IC50 values were calculated. Cell cycle and cell death were investigated through flow cytometry. Cytoskeleton organization was assessed through phalloidin+FITC staining. qPCR array and western blot were performed to analyze gene and protein expression. Curcumin reduced cell viability in a dose-dependent and selective manner, induced cell death on SCC-9 cells (necrosis/late apoptosis: 44% curcumin vs. 16.4% vehicle), and arrested cell cycle at phase G2 /M on SCC-9 and FaDu (G2 : SCC-9-19.1% curcumin vs. 13.4% vehicle; FaDu-37.8% curcumin vs. 12.9% vehicle). Disorganized cytoskeleton and altered cell morphology were observed. Furthermore, curcumin downregulated the PI3K-AKT-mTOR signaling pathway by modifying the expression of key genes and proteins. These findings highlight the promising therapeutic potential of curcumin to inhibit HNC growth and progression and to modulate the PI3K-AKT-mTOR pathway.
Collapse
Affiliation(s)
- Gabriel Alvares Borges
- Epithelial Biology Laboratory, Department of Periodontics and Oral Medicine, Division of Oral Pathology Oral Radiology and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA.,Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasilia, Brazil
| | - Silvia Taveira Elias
- Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasilia, Brazil
| | - Bruna Amorim
- Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasilia, Brazil
| | | | - Ricardo Della Coletta
- Department of Oral Diagnosis, School of Dentistry, University of Campinas, Piracicaba, Brazil
| | - Rogerio Moraes Castilho
- Epithelial Biology Laboratory, Department of Periodontics and Oral Medicine, Division of Oral Pathology Oral Radiology and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Cristiane Helena Squarize
- Epithelial Biology Laboratory, Department of Periodontics and Oral Medicine, Division of Oral Pathology Oral Radiology and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Eliete Neves Silva Guerra
- Epithelial Biology Laboratory, Department of Periodontics and Oral Medicine, Division of Oral Pathology Oral Radiology and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA.,Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasilia, Brazil
| |
Collapse
|
38
|
Cohen Katsenelson K, Stender JD, Kawashima AT, Lordén G, Uchiyama S, Nizet V, Glass CK, Newton AC. PHLPP1 counter-regulates STAT1-mediated inflammatory signaling. eLife 2019; 8:e48609. [PMID: 31408005 PMCID: PMC6692130 DOI: 10.7554/elife.48609] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 07/30/2019] [Indexed: 12/16/2022] Open
Abstract
Inflammation is an essential aspect of innate immunity but also contributes to diverse human diseases. Although much is known about the kinases that control inflammatory signaling, less is known about the opposing phosphatases. Here we report that deletion of the gene encoding PH domain Leucine-rich repeat Protein Phosphatase 1 (PHLPP1) protects mice from lethal lipopolysaccharide (LPS) challenge and live Escherichia coli infection. Investigation of PHLPP1 function in macrophages reveals that it controls the magnitude and duration of inflammatory signaling by dephosphorylating the transcription factor STAT1 on Ser727 to inhibit its activity, reduce its promoter residency, and reduce the expression of target genes involved in innate immunity and cytokine signaling. This previously undescribed function of PHLPP1 depends on a bipartite nuclear localization signal in its unique N-terminal extension. Our data support a model in which nuclear PHLPP1 dephosphorylates STAT1 to control the magnitude and duration of inflammatory signaling in macrophages.
Collapse
Affiliation(s)
| | - Joshua D Stender
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoSan DiegoUnited States
| | - Agnieszka T Kawashima
- Department of PharmacologyUniversity of California, San DiegoSan DiegoUnited States
- Department of Pharmacology and Biomedical Sciences Graduate ProgramUniversity of California, San DiegoSan DiegoUnited States
| | - Gema Lordén
- Department of PharmacologyUniversity of California, San DiegoSan DiegoUnited States
| | - Satoshi Uchiyama
- Department of PediatricsUniversity of California, San DiegoSan DiegoUnited States
| | - Victor Nizet
- Department of PediatricsUniversity of California, San DiegoSan DiegoUnited States
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California, San DiegoSan DiegoUnited States
| | - Christopher K Glass
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoSan DiegoUnited States
| | - Alexandra C Newton
- Department of PharmacologyUniversity of California, San DiegoSan DiegoUnited States
| |
Collapse
|