1
|
Terry AR, Nogueira V, Rho H, Ramakrishnan G, Li J, Kang S, Pathmasiri KC, Bhat SA, Jiang L, Kuchay S, Cologna SM, Hay N. CD36 maintains lipid homeostasis via selective uptake of monounsaturated fatty acids during matrix detachment and tumor progression. Cell Metab 2023; 35:2060-2076.e9. [PMID: 37852255 DOI: 10.1016/j.cmet.2023.09.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 04/11/2023] [Accepted: 09/21/2023] [Indexed: 10/20/2023]
Abstract
A high-fat diet (HFD) promotes metastasis through increased uptake of saturated fatty acids (SFAs). The fatty acid transporter CD36 has been implicated in this process, but a detailed understanding of CD36 function is lacking. During matrix detachment, endoplasmic reticulum (ER) stress reduces SCD1 protein, resulting in increased lipid saturation. Subsequently, CD36 is induced in a p38- and AMPK-dependent manner to promote preferential uptake of monounsaturated fatty acids (MUFAs), thereby maintaining a balance between SFAs and MUFAs. In attached cells, CD36 palmitoylation is required for MUFA uptake and protection from palmitate-induced lipotoxicity. In breast cancer mouse models, CD36-deficiency induced ER stress while diminishing the pro-metastatic effect of HFD, and only a palmitoylation-proficient CD36 rescued this effect. Finally, AMPK-deficient tumors have reduced CD36 expression and are metastatically impaired, but ectopic CD36 expression restores their metastatic potential. Our results suggest that, rather than facilitating HFD-driven tumorigenesis, CD36 plays a supportive role by preventing SFA-induced lipotoxicity.
Collapse
Affiliation(s)
- Alexander R Terry
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Veronique Nogueira
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Hyunsoo Rho
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Gopalakrishnan Ramakrishnan
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Jing Li
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Soeun Kang
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Koralege C Pathmasiri
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Sameer Ahmed Bhat
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Liping Jiang
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Shafi Kuchay
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Stephanie M Cologna
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Nissim Hay
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA; Research and Development Section, Jesse Brown VA Medical Center, Chicago, IL 60612, USA.
| |
Collapse
|
2
|
Bhat SA, Ferguson R, Adhikari R, Kuchay S. Detection of membrane-anchoring lipid modifications of proteins in cells by radioactive metabolic labeling. STAR Protoc 2023; 4:102416. [PMID: 37405928 PMCID: PMC10345189 DOI: 10.1016/j.xpro.2023.102416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/05/2023] [Accepted: 06/08/2023] [Indexed: 07/07/2023] Open
Abstract
Prenylation and palmitoylation are two major lipid modifications of cellular proteins that anchor proteins to cell membranes. Here, we present a protocol for detecting these modifications in cellular proteins by radioactive metabolic labeling. We describe steps for metabolic labeling of cells, cell harvesting for carrying out immunoprecipitations, subjecting immunocomplexes to SDS-PAGE, and transferring them to polyvinylidine flouride (PVDF) membranes. We then detail detection of labeled target proteins by exposing PVDF membranes to phosphor screens and using a phosphor imager machine. For complete details of this protocol, please refer to Liang et al.1.
Collapse
Affiliation(s)
- Sameer Ahmed Bhat
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1252, Chicago, IL 60607, USA
| | - Rachel Ferguson
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1252, Chicago, IL 60607, USA
| | - Ritika Adhikari
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1252, Chicago, IL 60607, USA
| | - Shafi Kuchay
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1252, Chicago, IL 60607, USA.
| |
Collapse
|
3
|
Giorgi C, Kuchay S. Editorial overview: Immune regulation and cancers. Curr Opin Pharmacol 2023; 69:102360. [PMID: 36870180 DOI: 10.1016/j.coph.2023.102360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
| | - Shafi Kuchay
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago IL-60607, USA.
| |
Collapse
|
4
|
Liang D, Jiang L, Bhat SA, Missiroli S, Perrone M, Lauriola A, Adhikari R, Gudur A, Vasi Z, Ahearn I, Guardavaccaro D, Giorgi C, Philips M, Kuchay S. Palmitoylation and PDE6δ regulate membrane-compartment-specific substrate ubiquitylation and degradation. Cell Rep 2023; 42:111999. [PMID: 36662618 PMCID: PMC9988375 DOI: 10.1016/j.celrep.2023.111999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 11/11/2022] [Accepted: 01/04/2023] [Indexed: 01/20/2023] Open
Abstract
Substrate degradation by the ubiquitin proteasome system (UPS) in specific membrane compartments remains elusive. Here, we show that the interplay of two lipid modifications and PDE6δ regulates compartmental substrate targeting via the SCFFBXL2. FBXL2 is palmitoylated in a prenylation-dependent manner on cysteines 417 and 419 juxtaposed to the CaaX motif. Palmitoylation/depalmitoylation regulates its subcellular trafficking for substrate engagement and degradation. To control its subcellular distribution, lipid-modified FBXL2 interacts with PDE6δ. Perturbing the equilibrium between FBXL2 and PDE6δ disrupts the delivery of FBXL2 to all membrane compartments, whereas depalmitoylated FBXL2 is enriched on the endoplasmic reticulum (ER). Depalmitoylated FBXL2(C417S/C419S) promotes the degradation of IP3R3 at the ER, inhibits IP3R3-dependent mitochondrial calcium overload, and counteracts calcium-dependent cell death upon oxidative stress. In contrast, disrupting the PDE6δ-FBXL2 equilibrium has the opposite effect. These findings describe a mechanism underlying spatially-restricted substrate degradation and suggest that inhibition of FBXL2 palmitoylation and/or binding to PDE6δ may offer therapeutic benefits.
Collapse
Affiliation(s)
- David Liang
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA
| | - Liping Jiang
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA
| | - Sameer Ahmed Bhat
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA
| | - Sonia Missiroli
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Mariasole Perrone
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Angela Lauriola
- Department of Biotechnology, University of Verona, 37134 Verona, Italy
| | - Ritika Adhikari
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA
| | - Anish Gudur
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA
| | - Zahra Vasi
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA
| | - Ian Ahearn
- Department of Dermatology and Perlmutter Cancer Center, New York University Grossman School of Medicine, New York, NY 10016, USA
| | | | - Carlotta Giorgi
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Mark Philips
- Department of Medicine and Perlmutter Cancer Center, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Shafi Kuchay
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, MBRB #1157, Chicago, IL 60607, USA.
| |
Collapse
|
5
|
Bhat SA, Vasi Z, Adhikari R, Gudur A, Ali A, Jiang L, Ferguson R, Liang D, Kuchay S. Ubiquitin proteasome system in immune regulation and therapeutics. Curr Opin Pharmacol 2022; 67:102310. [PMID: 36288660 PMCID: PMC10163937 DOI: 10.1016/j.coph.2022.102310] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 08/03/2022] [Accepted: 09/20/2022] [Indexed: 01/25/2023]
Abstract
The ubiquitin proteasome system (UPS) is a proteolytic machinery for the degradation of protein substrates that are post-translationally conjugated with ubiquitin polymers through the enzymatic action of ubiquitin ligases, in a process termed ubiquitylation. Ubiquitylation of substrates precedes their proteolysis via proteasomes, a hierarchical feature of UPS. E3-ubiquitin ligases recruit protein substrates providing specificity for ubiquitylation. Innate and adaptive immune system networks are regulated by ubiquitylation and substrate degradation via E3-ligases/UPS. Deregulation of E3-ligases/UPS components in immune cells is involved in the development of lymphomas, neurodevelopmental abnormalities, and cancers. Targeting E3-ligases for therapeutic intervention provides opportunities to mitigate the unintended broad effects of 26S proteasome inhibition. Recently, bifunctional moieties such as PROTACs and molecular glues have been developed to re-purpose E3-ligases for targeted degradation of unwanted aberrant proteins, with a potential for clinical use. Here, we summarize the involvement of E3-ligases/UPS components in immune-related diseases with perspectives.
Collapse
Affiliation(s)
- Sameer Ahmed Bhat
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Zahra Vasi
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Ritika Adhikari
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Anish Gudur
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Asceal Ali
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Liping Jiang
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Rachel Ferguson
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - David Liang
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA
| | - Shafi Kuchay
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago (UIC), Chicago, IL, 60607, USA.
| |
Collapse
|
6
|
Kuchay S, Saeed M, Giorgi C, Li J, Hoffmann HH, Pinton P, Rice CM, Pagano M. NS5A Promotes Constitutive Degradation of IP3R3 to Counteract Apoptosis Induced by Hepatitis C Virus. Cell Rep 2019; 25:833-840.e3. [PMID: 30355490 DOI: 10.1016/j.celrep.2018.09.088] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 07/17/2018] [Accepted: 09/26/2018] [Indexed: 01/28/2023] Open
Abstract
FBXL2 targets IP3R3 for ubiquitin-mediated degradation to limit Ca2+ flux to mitochondria and, consequently, apoptosis. Efficient replication of hepatitis C virus (HCV) requires geranylgeranylation of FBXL2. Here, we show that the viral protein NS5A forms a trimeric complex with IP3R3 and FBXL2, unmasking IP3R3's degron in the absence of inositol 1,4,5-trisphosphate (IP3) stimulation. FBXL2 knockdown or expression of a stable IP3R3 mutant causes persistent Ca2+ flux and sensitizes cells to apoptosis, resulting in the inhibition of viral replication. Importantly, the effect of FBXL2 silencing is rescued by depleting IP3R3, but not p85β, another established FBXL2 substrate, indicating that the anti-HCV effect of FBXL2 knockdown is largely due to IP3R3 stabilization. Finally, disruption of the FBXL2-NS5A-IP3R3 complex using somatic cell genetics or pharmacologic inhibition results in IP3R3 stabilization and suppression of HCV replication. This study reveals an IP3-independent molecular mechanism through which HCV promotes IP3R3 degradation, thereby inhibiting virus-induced apoptosis and establishing chronic infection.
Collapse
Affiliation(s)
- Shafi Kuchay
- Department of Biochemistry and Molecular Pharmacology, Laura and Isaac Perlmutter NYU Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, NY 10016, USA; Howard Hughes Medical Institute, 522 First Avenue, SRB 1107, New York, NY 10016, USA.
| | - Mohsan Saeed
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Carlotta Giorgi
- Department of Biochemistry and Molecular Pharmacology, Laura and Isaac Perlmutter NYU Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, NY 10016, USA; Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Jie Li
- Department of Biochemistry and Molecular Pharmacology, Laura and Isaac Perlmutter NYU Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, NY 10016, USA
| | - Hans-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA.
| | - Michele Pagano
- Department of Biochemistry and Molecular Pharmacology, Laura and Isaac Perlmutter NYU Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, NY 10016, USA; Howard Hughes Medical Institute, 522 First Avenue, SRB 1107, New York, NY 10016, USA.
| |
Collapse
|
7
|
Kuchay S, Wang H, Marzio A, Jain K, Homer H, Fehrenbacher N, Philips MR, Zheng N, Pagano M. GGTase3 is a newly identified geranylgeranyltransferase targeting a ubiquitin ligase. Nat Struct Mol Biol 2019; 26:628-636. [PMID: 31209342 PMCID: PMC6609460 DOI: 10.1038/s41594-019-0249-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 05/10/2019] [Indexed: 11/25/2022]
Abstract
Protein prenylation is believed to be catalyzed by three heterodimeric enzymes: FTase, GGTase1 and GGTase2. Here we report the identification of a previously unknown human prenyltransferase complex consisting of an orphan prenyltransferase α-subunit, PTAR1, and the catalytic β-subunit of GGTase2, RabGGTB. This enzyme, which we named GGTase3, geranylgeranylates FBXL2 to allow its localization at cell membranes, where this ubiquitin ligase mediates the polyubiquitylation of membrane-anchored proteins. In cells, FBXL2 is specifically recognized by GGTase3 despite having a typical carboxy-terminal CaaX prenylation motif that is predicted to be recognized by GGTase1. Our crystal structure analysis of the full-length GGTase3-FBXL2-SKP1 complex reveals an extensive multivalent interface specifically formed between the leucine-rich repeat domain of FBXL2 and PTAR1, which unmasks the structural basis of the substrate-enzyme specificity. By uncovering a missing prenyltransferase and its unique mode of substrate recognition, our findings call for a revision of the 'prenylation code'.
Collapse
Affiliation(s)
- Shafi Kuchay
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY, USA
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Hui Wang
- Department of Pharmacology, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Antonio Marzio
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA
| | - Kunj Jain
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA
| | - Harrison Homer
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA
| | - Nicole Fehrenbacher
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA
| | - Mark R Philips
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
| | - Michele Pagano
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY, USA.
- Perlmutter NYU Cancer Center, New York University School of Medicine, New York, NY, USA.
| |
Collapse
|
8
|
Bononi A, Yang H, Giorgi C, Patergnani S, Pellegrini L, Su M, Xie G, Signorato V, Pastorino S, Morris P, Sakamoto G, Kuchay S, Gaudino G, Pass HI, Napolitano A, Pinton P, Jia W, Carbone M. Germline BAP1 mutations induce a Warburg effect. Cell Death Differ 2017; 24:1694-1704. [PMID: 28665402 PMCID: PMC5596430 DOI: 10.1038/cdd.2017.95] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/09/2017] [Accepted: 02/24/2017] [Indexed: 12/26/2022] Open
Abstract
Carriers of heterozygous germline BAP1 mutations (BAP1+/−) develop cancer. We studied plasma from 16 BAP1+/− individuals from 2 families carrying different germline BAP1 mutations and 30 BAP1 wild-type (BAP1WT) controls from these same families. Plasma samples were analyzed by liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS), ultra-performance liquid chromatography triple quadrupole mass spectrometry (UPLC-TQ-MS), and gas chromatography time-of-flight mass spectrometry (GC-TOF-MS). We found a clear separation in the metabolic profile between BAP1WT and BAP1+/− individuals. We confirmed the specificity of the data in vitro using 12 cell cultures of primary fibroblasts we derived from skin punch biopsies from 12/46 of these same individuals, 6 BAP1+/− carriers and 6 controls from both families. BAP1+/− fibroblasts displayed increased aerobic glycolysis and lactate secretion, and reduced mitochondrial respiration and ATP production compared with BAP1WT. siRNA-mediated downregulation of BAP1 in primary BAP1WT fibroblasts and in primary human mesothelial cells, led to the same reduced mitochondrial respiration and increased aerobic glycolysis as we detected in primary fibroblasts from carriers of BAP1+/− mutations. The plasma and cell culture results were highly reproducible and were specifically and only linked to BAP1 status and not to gender, age or family, or cell type, and required an intact BAP1 catalytic activity. Accordingly, we were able to build a metabolomic model capable of predicting BAP1 status with 100% accuracy using data from human plasma. Our data provide the first experimental evidence supporting the hypothesis that aerobic glycolysis, also known as the ‘Warburg effect’, does not necessarily occur as an adaptive process that is consequence of carcinogenesis, but rather that it may also predate malignancy by many years and facilitate carcinogenesis.
Collapse
Affiliation(s)
- Angela Bononi
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Haining Yang
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Carlotta Giorgi
- Department of Morphology-Surgery-Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Simone Patergnani
- Department of Morphology-Surgery-Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Laura Pellegrini
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Mingming Su
- Metabolomics Unit, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Guoxiang Xie
- Metabolomics Unit, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Valentina Signorato
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA.,Department of Morphology-Surgery-Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Sandra Pastorino
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Paul Morris
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Greg Sakamoto
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Shafi Kuchay
- Cancer Center, New York University, New York, NY 10016, USA
| | - Giovanni Gaudino
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Harvey I Pass
- Cancer Center, New York University, New York, NY 10016, USA
| | - Andrea Napolitano
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Paolo Pinton
- Department of Morphology-Surgery-Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Wei Jia
- Metabolomics Unit, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Michele Carbone
- Thoracic Oncology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| |
Collapse
|
9
|
Fehrenbacher N, Tojal da Silva I, Ramirez C, Zhou Y, Cho KJ, Kuchay S, Shi J, Thomas S, Pagano M, Hancock JF, Bar-Sagi D, Philips MR. The G protein-coupled receptor GPR31 promotes membrane association of KRAS. J Cell Biol 2017; 216:2329-2338. [PMID: 28619714 PMCID: PMC5551702 DOI: 10.1083/jcb.201609096] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 04/05/2017] [Accepted: 05/12/2017] [Indexed: 12/14/2022] Open
Abstract
Mutant KRAS drives oncogenesis when associated with the plasma membrane. Fehrenbacher et al. identify GPR31, a G protein–coupled receptor, as a secretory pathway chaperone that guides the KRAS protein to the plasma membrane. The product of the KRAS oncogene, KRAS4B, promotes tumor growth when associated with the plasma membrane (PM). PM association is mediated, in part, by farnesylation of KRAS4B, but trafficking of nascent KRAS4B to the PM is incompletely understood. We performed a genome-wide screen to identify genes required for KRAS4B membrane association and identified a G protein–coupled receptor, GPR31. GPR31 associated with KRAS4B on cellular membranes in a farnesylation-dependent fashion, and retention of GPR31 on the endoplasmic reticulum inhibited delivery of KRAS4B to the PM. Silencing of GPR31 expression partially mislocalized KRAS4B, slowed the growth of KRAS-dependent tumor cells, and blocked KRAS-stimulated macropinocytosis. Our data suggest that GPR31 acts as a secretory pathway chaperone for KRAS4B.
Collapse
Affiliation(s)
- Nicole Fehrenbacher
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | | | - Craig Ramirez
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Yong Zhou
- Department of Integrative Biology and Pharmacology, The University of Texas Medical School at Houston, Houston, TX
| | - Kwang-Jin Cho
- Department of Integrative Biology and Pharmacology, The University of Texas Medical School at Houston, Houston, TX
| | - Shafi Kuchay
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY.,Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY.,Howard Hughes Medical Institute, New York, NY
| | - Jie Shi
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Susan Thomas
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Michele Pagano
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY.,Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY.,Howard Hughes Medical Institute, New York, NY
| | - John F Hancock
- Department of Integrative Biology and Pharmacology, The University of Texas Medical School at Houston, Houston, TX
| | - Dafna Bar-Sagi
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Mark R Philips
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| |
Collapse
|
10
|
Kuchay S, Giorgi C, Simoneschi D, Pagan J, Missiroli S, Saraf A, Florens L, Washburn MP, Collazo-Lorduy A, Castillo-Martin M, Cordon-Cardo C, Sebti SM, Pinton P, Pagano M. PTEN counteracts FBXL2 to promote IP3R3- and Ca 2+-mediated apoptosis limiting tumour growth. Nature 2017; 546:554-558. [PMID: 28614300 PMCID: PMC5627969 DOI: 10.1038/nature22965] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 05/04/2017] [Indexed: 12/12/2022]
Abstract
In response to environmental cues that promote IP3 (inositol 1,4,5-trisphosphate) generation, IP3 receptors (IP3Rs) located on the endoplasmic reticulum allow the ‘quasisynaptical’ feeding of calcium to the mitochondria to promote oxidative phosphorylation1. However, persistent Ca2+ release results in mitochondrial Ca2+ overload and consequent apoptosis2. Among the three mammalian IP3Rs, IP3R3 appears to be the major player in Ca2+-dependent apoptosis. Here we show that the F-box protein FBXL2 (the receptor subunit of one of 69 human SCF (SKP1, CUL1, F-box protein) ubiquitin ligase complexes3) binds IP3R3 and targets it for ubiquitin-, p97- and proteasome-mediated degradation to limit Ca2+ influx into mitochondria. FBXL2-knockdown cells and FBXL2-insensitive IP3R3 mutant knock-in clones display increased cytosolic Ca2+ release from the endoplasmic reticulum and sensitization to Ca2+-dependent apoptotic stimuli. The phosphatase and tensin homologue (PTEN) gene is frequently mutated or lost in human tumours and syndromes that predispose individuals to cancer4. We found that PTEN competes with FBXL2 for IP3R3 binding, and the FBXL2-dependent degradation of IP3R3 is accelerated in Pten−/− mouse embryonic fibroblasts and PTEN-null cancer cells. Reconstitution of PTEN-null cells with either wild-type PTEN or a catalytically dead mutant stabilizes IP3R3 and induces persistent Ca2+ mobilization and apoptosis. IP3R3 and PTEN protein levels directly correlate in human prostate cancer. Both in cell culture and xenograft models, a non-degradable IP3R3 mutant sensitizes tumour cells with low or no PTEN expression to photodynamic therapy, which is based on the ability of photosensitizer drugs to cause Ca2+-dependent cytotoxicity after irradiation with visible light5,6. Similarly, disruption of FBXL2 localization with GGTi-2418, a geranylgeranyl transferase inhibitor7, sensitizes xenotransplanted tumours to photodynamic therapy. In summary, we identify a novel molecular mechanism that limits mitochondrial Ca2+ overload to prevent cell death. Notably, we provide proof-of-principle that inhibiting IP3R3 degradation in PTEN-deregulated cancers represents a valid therapeutic strategy.
Collapse
Affiliation(s)
- Shafi Kuchay
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,NYU Perlmutter Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,Howard Hughes Medical Institute, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA
| | - Carlotta Giorgi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,NYU Perlmutter Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Daniele Simoneschi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,NYU Perlmutter Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA
| | - Julia Pagan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,NYU Perlmutter Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,Howard Hughes Medical Institute, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA
| | - Sonia Missiroli
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Anita Saraf
- The Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA
| | - Laurence Florens
- The Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA
| | - Michael P Washburn
- The Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA.,Department of Pathology and Laboratory Medicine, The University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, USA
| | - Ana Collazo-Lorduy
- Department of Pathology at Icahn School of Medicine at Mount Sinai, New York, New York 10029 USA.,Spanish Society of Medical Oncology, Madrid, Spain
| | - Mireia Castillo-Martin
- Department of Pathology at Icahn School of Medicine at Mount Sinai, New York, New York 10029 USA.,Department of Pathology at Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - Carlos Cordon-Cardo
- Department of Pathology at Icahn School of Medicine at Mount Sinai, New York, New York 10029 USA
| | - Said M Sebti
- Drug Discovery Department, Moffitt Cancer Center, and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612, USA
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Michele Pagano
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,NYU Perlmutter Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.,Howard Hughes Medical Institute, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA
| |
Collapse
|
11
|
Nabi MG, Wahid MA, Ahangar A, Kuchay S. Clinicopathological comparison of triple negative breast cancers with non-triple negative breast cancers in a hospital in North India. Niger J Clin Pract 2015; 18:381-6. [DOI: 10.4103/1119-3077.153248] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
12
|
Pandita KK, Razdan S, Kudyar RP, Beigh A, Kuchay S, Banday T. "Excess gooD can be Dangerous". A case series of iatrogenic symptomatic hypercalcemia due to hypervitaminosis D. Clin Cases Miner Bone Metab 2012; 9:118-120. [PMID: 23087723 PMCID: PMC3476516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Vitamin D is increasingly recognized to have several beneficial effects. Its toxicity, causing hypercalcemia, is considered as extremely rare. We report case series of 15 patients (most of them being elderly subjects) with iatrogenic symptomatic hypercalcemia in whom toxicity occurred due to empirical excessive administration of vitamin D by oral and parenteral route.
Collapse
Affiliation(s)
- Kamal Kishore Pandita
- Address for correspondence: Kamal Kishore Pandita, MD, 62/10, Swarn Vihar, PO Muthi, Jammu (J&K) India, Phone: +91-9419131670, E-mail: ;
| | | | | | | | | | | |
Collapse
|
13
|
Duan S, Skaar JR, Kuchay S, Toschi A, Kanarek N, Ben-Neriah Y, Pagano M. mTOR generates an auto-amplification loop by triggering the βTrCP- and CK1α-dependent degradation of DEPTOR. Mol Cell 2011; 44:317-24. [PMID: 22017877 DOI: 10.1016/j.molcel.2011.09.005] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 07/05/2011] [Accepted: 08/16/2011] [Indexed: 02/07/2023]
Abstract
DEPTOR is a recently identified inhibitor of the mTOR kinase that is highly regulated at the posttranslational level. In response to mitogens, we found that DEPTOR was rapidly phosphorylated on three serines in a conserved degron, facilitating binding and ubiquitylation by the F box protein βTrCP, with consequent proteasomal degradation of DEPTOR. Phosphorylation of the βTrCP degron in DEPTOR is executed by CK1α after a priming phosphorylation event mediated by either the mTORC1 or mTORC2 complexes. Blocking the βTrCP-dependent degradation of DEPTOR via βTrCP knockdown or expression of a stable DEPTOR mutant that is unable to bind βTrCP results in mTOR inhibition. Our findings reveal that mTOR cooperates with CK1α and βTrCP to generate an auto-amplification loop to promote its own full activation. Moreover, our results suggest that pharmacologic inhibition of CK1 may be a viable therapeutic option for the treatment of cancers characterized by activation of mTOR-signaling pathways.
Collapse
Affiliation(s)
- Shanshan Duan
- Department of Pathology, NYU Cancer Institute, New York University School of Medicine, New York, NY 10016, USA
| | | | | | | | | | | | | |
Collapse
|
14
|
Sha D, Jin Y, Wu H, Wei J, Lin CH, Lee YH, Buddhala C, Kuchay S, Chishti AH, Wu JY. Role of mu-calpain in proteolytic cleavage of brain L-glutamic acid decarboxylase. Brain Res 2008; 1207:9-18. [PMID: 18377878 DOI: 10.1016/j.brainres.2008.02.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 01/29/2008] [Accepted: 02/01/2008] [Indexed: 11/15/2022]
Abstract
Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme for gamma-aminobutyric acid (GABA) biosynthesis. Previously, we reported the presence of truncated forms of GAD in vivo and in vitro. In addition, an unidentified endogenous protease responsible for proteolytic cleavage of full-length GAD (fGAD) to its truncated form (tGAD) was also observed. In this communication, we report that mu-calpain is a good candidate for conversion of fGAD(67) to tGAD(67). This conclusion is based on the following observations: 1. purified recombinant GAD(67) is cleaved by mu-calpain at specific sites; 2. in brain synaptosomal preparation, GAD(67) is cleaved to its truncated form by an endogenous protease which is inhibited by specific calpain inhibitors; 3. in mu-calpain knockout mice, the level of tGAD in the brain is greatly reduced compared with the wild type; 4. when mu-calpain gene is silenced by siRNA, the level of tGAD is also markedly reduced compared to the control group; and 5. mu-calpain is activated by neuronal stimulation and Ca(2+)-influx. The physiological significance of calpain in regulation of GABA synthesis and GABAergic neurotransmission is also discussed.
Collapse
Affiliation(s)
- Di Sha
- Department of Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Sarang Z, Mádi A, Koy C, Varga S, Glocker MO, Ucker DS, Kuchay S, Chishti AH, Melino G, Fésüs L, Szondy Z. Tissue transglutaminase (TG2) facilitates phosphatidylserine exposure and calpain activity in calcium-induced death of erythrocytes. Cell Death Differ 2007; 14:1842-4. [PMID: 17612588 PMCID: PMC3968852 DOI: 10.1038/sj.cdd.4402193] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Z Sarang
- Department of Biochemistry and Molecular Biology, Signaling and Apoptosis Research Group, Hungarian Academy of Sciences, University of Debrecen, Debrecen H-4012, Hungary
| | - A Mádi
- Department of Biochemistry and Molecular Biology, Signaling and Apoptosis Research Group, Hungarian Academy of Sciences, University of Debrecen, Debrecen H-4012, Hungary
- Proteome Center Rostock, Medical Faculty, University of Rostock, Rostock D-18055, Germany
| | - C Koy
- Proteome Center Rostock, Medical Faculty, University of Rostock, Rostock D-18055, Germany
| | - S Varga
- Clinical Research Center, Laboratory for Electron Microscopy, University of Debrecen, Debrecen H-4012, Hungary
| | - MO Glocker
- Proteome Center Rostock, Medical Faculty, University of Rostock, Rostock D-18055, Germany
| | - DS Ucker
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - S Kuchay
- Department of Pharmacology, University of Illinois College of Medicine,Chicago, IL 60612, USA
| | - AH Chishti
- Department of Pharmacology, University of Illinois College of Medicine,Chicago, IL 60612, USA
| | - G Melino
- Fondazione S Lucia, Roma, Italy and Medical Research Council, Toxicology Unit, Hodgkin bld, Leicester LE1 9HN, UK
| | - L Fésüs
- Department of Biochemistry and Molecular Biology, Signaling and Apoptosis Research Group, Hungarian Academy of Sciences, University of Debrecen, Debrecen H-4012, Hungary
| | - Z Szondy
- Department of Biochemistry and Molecular Biology, Signaling and Apoptosis Research Group, Hungarian Academy of Sciences, University of Debrecen, Debrecen H-4012, Hungary
- Corresponding author: Z Szondy, Department of Biochemistry and Molecular Biology, University of Debrecen, Nagyerdei krt.98., Debrecen H-4012, Hungary. Tel: + 36 52 416432; Fax: + 36 52 314989;
| |
Collapse
|
16
|
Abstract
The objective of this investigation was to test the hypothesis that -calpain is largely responsible for postmortem proteolysis of muscle proteins. To accomplish this objective, we compared proteolysis of known muscle proteins in muscles of wild type and micro-calpain knockout mice during postmortem storage. Knockout mice (n = 6) were killed along with control mice (n = 6). Hind limbs were removed and stored at 4 degrees C. Muscles were dissected at 0, 1, and 3d postmortem and subsequently analyzed for degradation of nebulin, dystrophin, metavinculin, vinculin, desmin, and troponin T. In a separate experiment, hind limb muscles from knockout (n = 4) and control mice (n = 4) were analyzed at 0, 1, and 3 d postmortem using casein zymography to confirm that mu-calpain activity was knocked out in muscle and to determine whether or not m-calpain is activated in murine postmortem muscle. Cumulatively, the results of the first experiment indicated that postmortem proteolysis was largely inhibited in micro-calpain knockout mice. The results of the second experiment established the absence of micro-calpain in the muscle tissue of knockout mice and confirmed the results of an earlier study that m-calpain is active in postmortem murine muscle. The results of the current study show that even in a species in which m-calpain is activated to some extent postmortem, micro-calpain is largely responsible for postmortem proteolysis. This observation excludes a major role for any of the other members of the calpain family or any other proteolytic system in postmortem proteolysis of muscle proteins. Therefore, understanding the regulation of micro-calpain in postmortem muscle should be the focus of further research on postmortem proteolysis and tenderization of meat.
Collapse
Affiliation(s)
- G H Geesink
- CCL Research, Veghel, The Netherlands NL-5462
| | | | | | | |
Collapse
|
17
|
Grammer M, Kuchay S, Chishti A, Baudry M. Lack of phenotype for LTP and fear conditioning learning in calpain 1 knock-out mice. Neurobiol Learn Mem 2005; 84:222-7. [PMID: 16150618 DOI: 10.1016/j.nlm.2005.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 07/23/2005] [Accepted: 07/28/2005] [Indexed: 10/25/2022]
Abstract
We previously proposed the hypothesis that calpain activation played an important role in long-term potentiation (LTP) of synaptic transmission in hippocampus. Two forms of calpain are predominant in brain tissues, calpain 1 (mu-calpain), activated by micromolar calcium concentration and calpain 2 (m-calpain), activated by millimolar calcium concentration in vitro. In the present study, we tested the role of calpain 1 in LTP and in learning and memory using calpain 1 knock-out mice. Changes in learning and memory were assessed using both context and tone fear conditioning. No differences in freezing responses were observed between the knock-out and the wild-type animals during the acquisition phase of the training, eliminating the possibility that the knock-out animals could be differentially affected by the foot shock. Likewise, no differences in freezing responses elicited by either the context or the tone were observed during the retention phase. No differences in short-term potentiation (STP) or LTP were observed in hippocampal slices from the knock-out and matched wild-type mice. Several interpretations might explain these negative results. First, it is conceivable that calpain 2 plays a more dominant role in neurons, and that calpain 1 makes a minor contribution as opposed to its suspected predominant role in the hematopoietic system. Alternatively, it is conceivable that some as yet unknown compensatory mechanisms take effect, and that calpain 2 or another calpain isoform substitutes for the missing calpain 1.
Collapse
Affiliation(s)
- Michael Grammer
- Neuroscience Program, University of Southern California, Los Angeles, CA 90089-2520, USA.
| | | | | | | |
Collapse
|