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Vasquez OE, Allen AM, So AKC, Nguyen QH, Krause HM, Levine JD, Sokolowski MB. Characterizing the Protein Isoforms of foraging ( for), the PKGI Ortholog in Drosophila melanogaster. Int J Mol Sci 2023; 24:10219. [PMID: 37373366 DOI: 10.3390/ijms241210219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/05/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
The foraging (for) gene of Drosophila melanogaster encodes a cGMP-dependent protein kinase (PKG), which is a major effector of the cGMP signaling pathway involved in the regulation of behaviour and metabolic traits. Despite being well studied at the transcript level, little is known about the for gene at the protein level. Here, we provide a detailed characterization of the for gene protein (FOR) products and present new tools for their study, including five isoform-specific antibodies and a transgenic strain that carries an HA-labelled for allele (forBAC::HA). Our results showed that multiple FOR isoforms were expressed in the larval and adult stages of D. melanogaster and that the majority of whole-body FOR expression arises from three (P1, P1α, and P3) of eight putative protein isoforms. We found that FOR expression differed between the larval and adult stages and between the dissected larval organs we analyzed, which included the central nervous system (CNS), fat body, carcass, and intestine. Moreover, we showed that the FOR expression differed between two allelic variants of the for gene, namely, fors (sitter) and forR (rover), that are known to differ in many food-related traits. Together, our in vivo identification of FOR isoforms and the existence of temporal, spatial, and genetic differences in their expression lay the groundwork for determining their functional significance.
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Affiliation(s)
- Oscar E Vasquez
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Aaron M Allen
- Centre for Neural Circuits and Behaviour, Oxford University, Oxford OX1 3SR, UK
| | - Anthony K-C So
- Department of Biology, University of Toronto at Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Quynh H Nguyen
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Henry M Krause
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Joel D Levine
- Department of Biology, University of Toronto at Mississauga, Mississauga, ON L5L 1C6, Canada
- Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada
| | - Marla B Sokolowski
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
- Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada
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2
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Detection and Characterization of Phosphorylation, Glycosylation, and Fatty Acid Bound to Fetuin A in Human Blood. J Clin Med 2021; 10:jcm10030411. [PMID: 33499061 PMCID: PMC7865524 DOI: 10.3390/jcm10030411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/12/2021] [Accepted: 01/18/2021] [Indexed: 01/12/2023] Open
Abstract
The hepatokine fetuin A (Fet A) has been associated with diverse pathological states such as insulin resistance, type 2 diabetes, macrovascular disease, and systemic ectopic and vascular calcification. Fet A may also play a role in tumor growth and metastasis. The biological activity of Fet A may be affected by various modifications, including phosphorylation, O- and N-glycosylation and fatty acid binding. We developed an antibody-based assay for the detection of Fet A phosphorylated at serine 312. Fatty acid pattern was determined by gas chromatography. Using the antibody, we found that the phosphorylation was stable in human plasma or serum at room temperature for 8 h. We observed that Fet A is present in several glycosylation forms in human plasma, but the extent of Ser312 phosphorylation was not associated with glycosylation. The phosphorylation pattern did not change during an oral glucose tolerance test (0–120 min). We further found that human Fet A binds preferentially saturated fatty acids (>90%) at the expense of mono- and poly-unsaturated fatty acids. Our results indicate that different molecular species of Fet A are present in human plasma and that these different modifications may determine the different biological effects of Fet A.
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Chan MH, Aminzai S, Hu T, Taran A, Li S, Kim C, Pilz RB, Casteel DE. A substitution in cGMP-dependent protein kinase 1 associated with aortic disease induces an active conformation in the absence of cGMP. J Biol Chem 2020; 295:10394-10405. [PMID: 32506052 DOI: 10.1074/jbc.ra119.010984] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 06/04/2020] [Indexed: 01/27/2023] Open
Abstract
Type 1 cGMP-dependent protein kinases (PKGs) play important roles in human cardiovascular physiology, regulating vascular tone and smooth-muscle cell phenotype. A mutation in the human PRKG1 gene encoding cGMP-dependent protein kinase 1 (PKG1) leads to thoracic aortic aneurysms and dissections. The mutation causes an arginine-to-glutamine (RQ) substitution within the first cGMP-binding pocket in PKG1. This substitution disrupts cGMP binding to the pocket, but it also unexpectedly causes PKG1 to have high activity in the absence of cGMP via an unknown mechanism. Here, we identified the molecular mechanism whereby the RQ mutation increases basal kinase activity in the human PKG1α and PKG1β isoforms. Although we found that the RQ substitution (R177Q in PKG1α and R192Q in PKG1β) increases PKG1α and PKG1β autophosphorylation in vitro, we did not detect increased autophosphorylation of the PKG1α or PKG1β RQ variant isolated from transiently transfected 293T cells, indicating that increased basal activity of the RQ variants in cells was not driven by PKG1 autophosphorylation. Replacement of Arg-177 in PKG1α with alanine or methionine also increased basal activity. PKG1 exists as a parallel homodimer linked by an N-terminal leucine zipper, and we show that the WT chain in WT-RQ heterodimers partly reduces basal activity of the RQ chain. Using hydrogen/deuterium-exchange MS, we found that the RQ substitution causes PKG1β to adopt an active conformation in the absence of cGMP, similar to that of cGMP-bound WT enzyme. We conclude that the RQ substitution in PKG1 increases its basal activity by disrupting the formation of an inactive conformation.
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Affiliation(s)
- Matthew H Chan
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Sahar Aminzai
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Tingfei Hu
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Amatya Taran
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Sheng Li
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Choel Kim
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology and the Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Renate B Pilz
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Darren E Casteel
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
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Bohnert BN, Menacher M, Janessa A, Wörn M, Schork A, Daiminger S, Kalbacher H, Häring HU, Daniel C, Amann K, Sure F, Bertog M, Haerteis S, Korbmacher C, Artunc F. Aprotinin prevents proteolytic epithelial sodium channel (ENaC) activation and volume retention in nephrotic syndrome. Kidney Int 2018; 93:159-172. [DOI: 10.1016/j.kint.2017.07.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 07/24/2017] [Accepted: 07/27/2017] [Indexed: 10/18/2022]
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5
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Kirk JA, Holewinski RJ, Crowgey EL, Van Eyk JE. Protein kinase G signaling in cardiac pathophysiology: Impact of proteomics on clinical trials. Proteomics 2016; 16:894-905. [PMID: 26670943 DOI: 10.1002/pmic.201500401] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 11/16/2015] [Accepted: 12/09/2015] [Indexed: 01/09/2023]
Abstract
The protective role of cyclic guanosine monophosphate (cGMP)-stimulated protein kinase G (PKG) in the heart makes it an attractive target for therapeutic drug development to treat a variety of cardiac diseases. Phosphodiesterases degrade cGMP, thus phosphodiesterase inhibitors that can increase PKG are of translational interest and the subject of ongoing human trials. PKG signaling is complex, however, and understanding its downstream phosphorylation targets and upstream regulation are necessary steps toward safe and efficacious drug development. Proteomic technologies have paved the way for assays that allow us to peer broadly into signaling minutia, including protein quantity changes and phosphorylation events. However, there are persistent challenges to the proteomic study of PKG, such as the impact of the expression of different PKG isoforms, changes in its localization within the cell, and alterations caused by oxidative stress. PKG signaling is also dependent upon sex and potentially the genetic and epigenetic background of the individual. Thus, the rigorous application of proteomics to the field will be necessary to address how these effectors can alter PKG signaling and interfere with pharmacological interventions. This review will summarize PKG signaling, how it is being targeted clinically, and the proteomic challenges and techniques that are being used to study it.
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Affiliation(s)
- Jonathan A Kirk
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood, IL, USA
| | - Ronald J Holewinski
- Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Erin L Crowgey
- Center for Bioinformatics & Computational Biology, University of Delaware, Newark, DE, USA
| | - Jennifer E Van Eyk
- Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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