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Fan Z, Hao Y, Huo Y, Cao F, Li L, Xu J, Song Y, Yang K. Modulators for palmitoylation of proteins and small molecules. Eur J Med Chem 2024; 271:116408. [PMID: 38621327 DOI: 10.1016/j.ejmech.2024.116408] [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: 02/09/2024] [Revised: 04/03/2024] [Accepted: 04/10/2024] [Indexed: 04/17/2024]
Abstract
As an essential form of lipid modification for maintaining vital cellular functions, palmitoylation plays an important role in in the regulation of various physiological processes, serving as a promising therapeutic target for diseases like cancer and neurological disorders. Ongoing research has revealed that palmitoylation can be categorized into three distinct types: N-palmitoylation, O-palmitoylation and S-palmitoylation. Herein this paper provides an overview of the regulatory enzymes involved in palmitoylation, including palmitoyltransferases and depalmitoylases, and discusses the currently available broad-spectrum and selective inhibitors for these enzymes.
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Affiliation(s)
- Zeshuai Fan
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China
| | - Yuchen Hao
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China
| | - Yidan Huo
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China
| | - Fei Cao
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China; Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding, Hebei, 071002, China
| | - Longfei Li
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China; Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding, Hebei, 071002, China
| | - Jianmei Xu
- Department of hematopathology, Affiliated Hospital of Hebei University, Hebei University, Baoding, 071002, China
| | - Yali Song
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China; Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding, Hebei, 071002, China
| | - Kan Yang
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Hebei University, Baoding, 071002, China; Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding, Hebei, 071002, China.
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Buszka A, Pytyś A, Colvin D, Włodarczyk J, Wójtowicz T. S-Palmitoylation of Synaptic Proteins in Neuronal Plasticity in Normal and Pathological Brains. Cells 2023; 12:cells12030387. [PMID: 36766729 PMCID: PMC9913408 DOI: 10.3390/cells12030387] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/08/2023] [Accepted: 01/17/2023] [Indexed: 01/24/2023] Open
Abstract
Protein lipidation is a common post-translational modification of proteins that plays an important role in human physiology and pathology. One form of protein lipidation, S-palmitoylation, involves the addition of a 16-carbon fatty acid (palmitate) onto proteins. This reversible modification may affect the regulation of protein trafficking and stability in membranes. From multiple recent experimental studies, a picture emerges whereby protein S-palmitoylation is a ubiquitous yet discrete molecular switch enabling the expansion of protein functions and subcellular localization in minutes to hours. Neural tissue is particularly rich in proteins that are regulated by S-palmitoylation. A surge of novel methods of detection of protein lipidation at high resolution allowed us to get better insights into the roles of protein palmitoylation in brain physiology and pathophysiology. In this review, we specifically discuss experimental work devoted to understanding the impact of protein palmitoylation on functional changes in the excitatory and inhibitory synapses associated with neuronal activity and neuronal plasticity. The accumulated evidence also implies a crucial role of S-palmitoylation in learning and memory, and brain disorders associated with impaired cognitive functions.
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Shimell JJ, Shah BS, Cain SM, Thouta S, Kuhlmann N, Tatarnikov I, Jovellar DB, Brigidi GS, Kass J, Milnerwood AJ, Snutch TP, Bamji SX. The X-Linked Intellectual Disability Gene Zdhhc9 Is Essential for Dendrite Outgrowth and Inhibitory Synapse Formation. Cell Rep 2020; 29:2422-2437.e8. [PMID: 31747610 DOI: 10.1016/j.celrep.2019.10.065] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/09/2019] [Accepted: 10/13/2019] [Indexed: 11/29/2022] Open
Abstract
Palmitoylation is a reversible post-translational lipid modification that facilitates vesicular transport and subcellular localization of modified proteins. This process is catalyzed by ZDHHC enzymes that are implicated in several neurological and neurodevelopmental disorders. Loss-of-function mutations in ZDHHC9 have been identified in patients with X-linked intellectual disability (XLID) and associated with increased epilepsy risk. Loss of Zdhhc9 function in hippocampal cultures leads to shorter dendritic arbors and fewer inhibitory synapses, altering the ratio of excitatory-to-inhibitory inputs formed onto Zdhhc9-deficient cells. While Zdhhc9 promotes dendrite outgrowth through the palmitoylation of the GTPase Ras, it promotes inhibitory synapse formation through the palmitoylation of another GTPase, TC10. Zdhhc9 knockout mice exhibit seizure-like activity together with increased frequency and amplitude of both spontaneous and miniature excitatory and inhibitory postsynaptic currents. These findings present a plausible mechanism for how the loss of ZDHHC9 function may contribute to XLID and epilepsy.
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Affiliation(s)
- Jordan J Shimell
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Bhavin S Shah
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Stuart M Cain
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Samrat Thouta
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Naila Kuhlmann
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - Igor Tatarnikov
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - D Blair Jovellar
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - G Stefano Brigidi
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Jennifer Kass
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Austen J Milnerwood
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Shernaz X Bamji
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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The Slo(w) path to identifying the mitochondrial channels responsible for ischemic protection. Biochem J 2017; 474:2067-2094. [PMID: 28600454 DOI: 10.1042/bcj20160623] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria play an important role in tissue ischemia and reperfusion (IR) injury, with energetic failure and the opening of the mitochondrial permeability transition pore being the major causes of IR-induced cell death. Thus, mitochondria are an appropriate focus for strategies to protect against IR injury. Two widely studied paradigms of IR protection, particularly in the field of cardiac IR, are ischemic preconditioning (IPC) and volatile anesthetic preconditioning (APC). While the molecular mechanisms recruited by these protective paradigms are not fully elucidated, a commonality is the involvement of mitochondrial K+ channel opening. In the case of IPC, research has focused on a mitochondrial ATP-sensitive K+ channel (mitoKATP), but, despite recent progress, the molecular identity of this channel remains a subject of contention. In the case of APC, early research suggested the existence of a mitochondrial large-conductance K+ (BK, big conductance of potassium) channel encoded by the Kcnma1 gene, although more recent work has shown that the channel that underlies APC is in fact encoded by Kcnt2 In this review, we discuss both the pharmacologic and genetic evidence for the existence and identity of mitochondrial K+ channels, and the role of these channels both in IR protection and in regulating normal mitochondrial function.
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Li L, Luo Q, Xiao W, Li J, Zhou S, Li Y, Zheng X, Yang H. A machine-learning approach for predicting palmitoylation sites from integrated sequence-based features. J Bioinform Comput Biol 2016; 15:1650025. [PMID: 27411307 DOI: 10.1142/s0219720016500256] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Palmitoylation is the covalent attachment of lipids to amino acid residues in proteins. As an important form of protein posttranslational modification, it increases the hydrophobicity of proteins, which contributes to the protein transportation, organelle localization, and functions, therefore plays an important role in a variety of cell biological processes. Identification of palmitoylation sites is necessary for understanding protein-protein interaction, protein stability, and activity. Since conventional experimental techniques to determine palmitoylation sites in proteins are both labor intensive and costly, a fast and accurate computational approach to predict palmitoylation sites from protein sequences is in urgent need. In this study, a support vector machine (SVM)-based method was proposed through integrating PSI-BLAST profile, physicochemical properties, [Formula: see text]-mer amino acid compositions (AACs), and [Formula: see text]-mer pseudo AACs into the principal feature vector. A recursive feature selection scheme was subsequently implemented to single out the most discriminative features. Finally, an SVM method was implemented to predict palmitoylation sites in proteins based on the optimal features. The proposed method achieved an accuracy of 99.41% and Matthews Correlation Coefficient of 0.9773 for a benchmark dataset. The result indicates the efficiency and accuracy of our method in prediction of palmitoylation sites based on protein sequences.
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Affiliation(s)
- Liqi Li
- * Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Qifa Luo
- * Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Weidong Xiao
- * Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Jinhui Li
- * Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Shiwen Zhou
- † National Drug Clinical Trial Institution, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Yongsheng Li
- ‡ Institute of Cancer, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xiaoqi Zheng
- § Department of Mathematics, Shanghai Normal University, Shanghai 200234, China
| | - Hua Yang
- * Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
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Peng S, Xu J, Pelkey KA, Chandra G, Zhang Z, Bagh MB, Yuan X, Wu LG, McBain CJ, Mukherjee AB. Suppression of agrin-22 production and synaptic dysfunction in Cln1 (-/-) mice. Ann Clin Transl Neurol 2015; 2:1085-104. [PMID: 26734660 PMCID: PMC4693586 DOI: 10.1002/acn3.261] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/10/2015] [Accepted: 10/02/2015] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE Oxidative stress in the brain is highly prevalent in many neurodegenerative disorders including lysosomal storage disorders, in which neurodegeneration is a devastating manifestation. Despite intense studies, a precise mechanism linking oxidative stress to neuropathology in specific neurodegenerative diseases remains largely unclear. METHODS Infantile neuronal ceroid lipofuscinosis (INCL) is a devastating neurodegenerative lysosomal storage disease caused by mutations in the ceroid lipofuscinosis neuronal-1 (CLN1) gene encoding palmitoyl-protein thioesterase-1. Previously, we reported that in the brain of Cln1 (-/-) mice, which mimic INCL, and in postmortem brain tissues from INCL patients, increased oxidative stress is readily detectable. We used molecular, biochemical, immunohistological, and electrophysiological analyses of brain tissues of Cln1 (-/-) mice to study the role(s) of oxidative stress in mediating neuropathology. RESULTS Our results show that in Cln1 (-/-) mice oxidative stress in the brain via upregulation of the transcription factor, CCAAT/enhancer-binding protein-δ, stimulated expression of serpina1, which is an inhibitor of a serine protease, neurotrypsin. Moreover, in the Cln1 (-/-) mice, suppression of neurotrypsin activity by serpina1 inhibited the cleavage of agrin (a large proteoglycan), which substantially reduced the production of agrin-22, essential for synaptic homeostasis. Direct whole-cell recordings at the nerve terminals of Cln1 (-/-) mice showed inhibition of Ca(2+) currents attesting to synaptic dysfunction. Treatment of these mice with a thioesterase-mimetic small molecule, N-tert (Butyl) hydroxylamine (NtBuHA), increased agrin-22 levels. INTERPRETATION Our findings provide insight into a novel pathway linking oxidative stress with synaptic pathology in Cln1 (-/-) mice and suggest that NtBuHA, which increased agrin-22 levels, may ameliorate synaptic dysfunction in this devastating neurodegenerative disease.
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Affiliation(s)
- Shiyong Peng
- Section on Developmental Genetics Program on Developmental Endocrinology and Genetics Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-1830
| | - Jianhua Xu
- Synaptic Transmission Section (HNQ23-R) National Institute of Neurological Disorders and Stroke NIH Bethesda Maryland 20892
| | - Kenneth A Pelkey
- The Program in Developmental Neuroscience Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-3715
| | - Goutam Chandra
- Section on Developmental Genetics Program on Developmental Endocrinology and Genetics Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-1830
| | - Zhongjian Zhang
- Section on Developmental Genetics Program on Developmental Endocrinology and Genetics Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-1830
| | - Maria B Bagh
- Section on Developmental Genetics Program on Developmental Endocrinology and Genetics Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-1830
| | - Xiaoqing Yuan
- The Program in Developmental Neuroscience Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-3715
| | - Ling-Gang Wu
- Synaptic Transmission Section (HNQ23-R) National Institute of Neurological Disorders and Stroke NIH Bethesda Maryland 20892
| | - Chris J McBain
- The Program in Developmental Neuroscience Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-3715
| | - Anil B Mukherjee
- Section on Developmental Genetics Program on Developmental Endocrinology and Genetics Eunice Kennedy-Shriver National Institute of Child Health and Human Development NIH Bethesda Maryland 20892-1830
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Leo A, Citraro R, Constanti A, De Sarro G, Russo E. Are big potassium-type Ca2+-activated potassium channels a viable target for the treatment of epilepsy? Expert Opin Ther Targets 2015; 19:911-26. [DOI: 10.1517/14728222.2015.1026258] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Abstract
Lipid metabolism is regulated by multiple signaling pathways, and generates a variety of bioactive lipid molecules. These bioactive lipid molecules known as signaling molecules, such as fatty acid, eicosanoids, diacylglycerol, phosphatidic acid, lysophophatidic acid, ceramide, sphingosine, sphingosine-1-phosphate, phosphatidylinositol-3 phosphate, and cholesterol, are involved in the activation or regulation of different signaling pathways. Lipid metabolism participates in the regulation of many cellular processes such as cell growth, proliferation, differentiation, survival, apoptosis, inflammation, motility, membrane homeostasis, chemotherapy response, and drug resistance. Bioactive lipid molecules promote apoptosis via the intrinsic pathway by modulating mitochondrial membrane permeability and activating different enzymes including caspases. In this review, we discuss recent data in the fields of lipid metabolism, lipid-mediated apoptosis, and cancer therapy. In conclusion, understanding the underlying molecular mechanism of lipid metabolism and the function of different lipid molecules could provide the basis for cancer cell death rationale, discover novel and potential targets, and develop new anticancer drugs for cancer therapy.
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N'Gouemo P. BKCa channel dysfunction in neurological diseases. Front Physiol 2014; 5:373. [PMID: 25324781 PMCID: PMC4179377 DOI: 10.3389/fphys.2014.00373] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/10/2014] [Indexed: 12/22/2022] Open
Abstract
The large conductance, Ca2+-activated K+ channels (BKCa, KCa1.1) are expressed in various brain neurons where they play important roles in regulating action potential duration, firing frequency and neurotransmitter release. Membrane potential depolarization and rising levels of intracellular Ca2+ gated BKCa channels, which in turn results in an outward K+ flux that re/hyperpolarizes the membrane. The sensitivity of BKCa channels to Ca2+ provides an important negative-feedback system for Ca2+ entry into brain neurons and suppresses repetitive firing. Thus, BKCa channel loss-of-function gives rise to neuronal hyperexcitability, which can lead to seizures. Evidence also indicates that BKCa channels can facilitate high-frequency firing (gain-of-function) in some brain neurons. Interestingly, both gain-of-function and loss-of-function mutations of genes encoding for various BKCa channel subunits have been associated with the development of neuronal excitability disorders, such as seizure disorders. The role of BKCa channels in the etiology of some neurological diseases raises the possibility that these channels can be used as molecular targets to prevent and suppress disease phenotypes.
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Affiliation(s)
- Prosper N'Gouemo
- Department of Pediatrics and Interdisciplinary Program in Neuroscience, Georgetown University Medical Center Washington, DC, USA
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Shipston MJ. S-acylation dependent post-translational cross-talk regulates large conductance calcium- and voltage- activated potassium (BK) channels. Front Physiol 2014; 5:281. [PMID: 25140154 PMCID: PMC4122160 DOI: 10.3389/fphys.2014.00281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 07/09/2014] [Indexed: 01/14/2023] Open
Abstract
Mechanisms that control surface expression and/or activity of large conductance calcium-activated potassium (BK) channels are important determinants of their (patho)physiological function. Indeed, BK channel dysfunction is associated with major human disorders ranging from epilepsy to hypertension and obesity. S-acylation (S-palmitoylation) represents a major reversible, post-translational modification controlling the properties and function of many proteins including ion channels. Recent evidence reveals that both pore-forming and regulatory subunits of BK channels are S-acylated and control channel trafficking and regulation by AGC-family protein kinases. The pore-forming α-subunit is S-acylated at two distinct sites within the N- and C-terminus, each site being regulated by different palmitoyl acyl transferases (zDHHCs) and acyl thioesterases (APTs). S-acylation of the N-terminus controls channel trafficking and surface expression whereas S-acylation of the C-terminal domain determines regulation of channel activity by AGC-family protein kinases. S-acylation of the regulatory β4-subunit controls ER exit and surface expression of BK channels but does not affect ion channel kinetics at the plasma membrane. Furthermore, a significant number of previously identified BK-channel interacting proteins have been shown, or are predicted to be, S-acylated. Thus, the BK channel multi-molecular signaling complex may be dynamically regulated by this fundamental post-translational modification and thus S-acylation likely represents an important determinant of BK channel physiology in health and disease.
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Affiliation(s)
- Michael J Shipston
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh Edinburgh, UK
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Large conductance Ca2+-activated K+ channel (BKCa) α-subunit splice variants in resistance arteries from rat cerebral and skeletal muscle vasculature. PLoS One 2014; 9:e98863. [PMID: 24921651 PMCID: PMC4055454 DOI: 10.1371/journal.pone.0098863] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 05/07/2014] [Indexed: 11/19/2022] Open
Abstract
Previous studies report functional differences in large conductance Ca2+ activated-K+ channels (BKCa) of smooth muscle cells (VSMC) from rat cerebral and cremaster muscle resistance arteries. The present studies aimed to determine if this complexity in BKCa activity may, in part, be due to splice variants in the pore-forming α-subunit. BKCa variants in the intracellular C terminus of the α-subunit, and their relative expression to total α-subunit, were examined by qPCR. Sequencing of RT-PCR products showed two α-subunit variants, ZERO and STREX, to be identical in cremaster and cerebral arteries. Levels of STREX mRNA expression were, however, significantly higher in cremaster VSMCs (28.9±4.2% of total α-BKCa) compared with cerebral vessels (16.5±0.9%). Further, a low level of BKCa SS4 α-subunit variant was seen in cerebral arteries, while undetectable in cremaster arteries. Protein biotinylation assays, in expression systems and arterial preparations, were used to determine whether differences in splice variant mRNA expression affect surface membrane/cytosolic location of the channel. In AD-293 and CHO-K1 cells, rat STREX was more likely to be located at the plasma membrane compared to ZERO, although the great majority of channel protein was in the membrane in both cases. Co-expression of β1-BKCa subunit with STREX or ZERO did not influence the dominant membrane expression of α-BKCa subunits, whereas in the absence of α-BKCa, a significant proportion of β1-subunit remained cytosolic. Biotinylation assays of cremaster and cerebral arteries showed that differences in STREX/ZERO expression do not alter membrane/cytosolic distribution of the channel under basal conditions. These data, however, revealed that the amount of α-BKCa in cerebral arteries is approximately 20X higher than in cremaster vessels. Thus, the data support the major functional differences in BKCa activity in cremaster, as compared to cerebral VSMCs, being related to total α-BKCa expression, regardless of differences in splice variant expression.
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CRL4A(CRBN) E3 ubiquitin ligase restricts BK channel activity and prevents epileptogenesis. Nat Commun 2014; 5:3924. [PMID: 24845235 DOI: 10.1038/ncomms4924] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 04/17/2014] [Indexed: 12/29/2022] Open
Abstract
Ion channels regulate membrane excitation, and mutations of ion channels often cause serious neurological disorders including epilepsy. Compared with extensive analyses of channel protein structure and function, much less is known about the fine tuning of channel activity by post-translational modification. Here we report that the large conductance, Ca(2+)- and voltage-activated K(+) (BK) channels are targeted by the E3 ubiquitin ligase CRL4A(CRBN) for polyubiquitination and retained in the endoplasmic reticulum (ER). Inactivation of CRL4A(CRBN) releases deubiquitinated BK channels from the ER to the plasma membrane, leading to markedly enhanced channel activity. Mice with CRL4A(CRBN) mutation in the brain or treated with a CRL4A(CRBN) inhibitor are very sensitive to seizure induction, which can be attenuated by blocking BK channels. Finally, the mutant mice develop spontaneous epilepsy when aged. Therefore, ubiquitination of BK channels before their cell surface expression is an important step to prevent systemic neuronal excitability and epileptogenesis.
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Plant LD. Multilevel regulation: Controlling BK channels in central clock neurons. J Gen Physiol 2013; 142:579-83. [PMID: 24277601 PMCID: PMC3840922 DOI: 10.1085/jgp.201311128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Leigh D Plant
- Department of Biochemistry, Brandeis University, Waltham, MA 02453
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