-
Molecular Neurobiology Mar 2021Protein prenylation is a post-translational lipid modification that governs a variety of important cellular signaling pathways, including those regulating synaptic...
Protein prenylation is a post-translational lipid modification that governs a variety of important cellular signaling pathways, including those regulating synaptic functions and cognition in the nervous system. Two enzymes, farnesyltransferase (FT) and geranylgeranyltransferase type I (GGT), are essential for the prenylation process. Genetic reduction of FT or GGT ameliorates neuropathology but only FT haplodeficiency rescues cognitive function in transgenic mice of Alzheimer's disease. A follow-up study showed that systemic or forebrain neuron-specific deficiency of GGT leads to synaptic and cognitive deficits under physiological conditions. Whether FT plays different roles in shaping neuronal functions and cognition remains elusive. This study shows that in contrast to the detrimental effects of GGT reduction, systemic haplodeficiency of FT has little to no impact on hippocampal synaptic plasticity and cognition. However, forebrain neuron-specific FT deletion also leads to reduced synaptic plasticity, memory retention, and hippocampal dendritic spine density. Furthermore, a novel prenylomic analysis identifies distinct pools of prenylated proteins that are affected in the brain of forebrain neuron-specific FT and GGT knockout mice, respectively. Taken together, this study uncovers that physiological levels of FT and GGT in neurons are essential for normal synaptic/cognitive functions and that the prenylation status of specific signaling molecules regulates neuronal functions.
Topics: Alkyl and Aryl Transferases; Animals; Cognition; Dendritic Spines; Hippocampus; Long-Term Potentiation; Maze Learning; Mice; Neuronal Plasticity; Neurons; Protein Prenylation; Spatial Learning; Spatial Memory; Synapses
PubMed: 33098528
DOI: 10.1007/s12035-020-02169-w -
Mycopathologia Dec 2014Pathogenic fungi employ numerous mechanisms to flourish in the stressful environment encountered within their mammalian hosts. Central to this arsenal for filamentous... (Review)
Review
Pathogenic fungi employ numerous mechanisms to flourish in the stressful environment encountered within their mammalian hosts. Central to this arsenal for filamentous fungi is invasive growth within the host microenvironment, mediated by establishment and maintenance of polarized hyphal morphogenesis. In Aspergillus fumigatus, the RasA signal transduction pathway has emerged as a significant regulator of hyphal morphogenesis and virulence, among other processes. The factors contributing to the regulation of RasA itself are not as thoroughly understood, although proper temporal activation of RasA and spatial localization of RasA to the plasma membrane are known to play major roles. Interference with RasA palmitoylation or prenylation results in mislocalization of RasA and is associated with severe growth deficits. In addition, dysregulation of RasA activation results in severe morphologic aberrancies and growth deficits. This review highlights the relationship between RasA signaling, hyphal morphogenesis, and virulence in A. fumigatus and focuses on potential determinants of spatial and temporal RasA regulation.
Topics: Aspergillus fumigatus; Gene Expression Regulation, Fungal; Hyphae; Lipoylation; Protein Prenylation; Signal Transduction; Virulence; ras Proteins
PubMed: 24952717
DOI: 10.1007/s11046-014-9765-1 -
Biochimica Et Biophysica Acta Aug 2010The mevalonate pathway is a crucial metabolic pathway for most eukaryotic cells. Cholesterol is a highly recognized product of this pathway but growing interest is being... (Review)
Review
The mevalonate pathway is a crucial metabolic pathway for most eukaryotic cells. Cholesterol is a highly recognized product of this pathway but growing interest is being given to the synthesis and functions of isoprenoids. Isoprenoids are a complex class of biologically active lipids including for example, dolichol, ubiquinone, farnesylpyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). Early work had shown that the long-chain isoprenoid dolichol is decreased but that dolichyl phosphate and ubiquinone are elevated in brains of Alzheimer's disease (AD) patients. Until recently, levels of their biological active precursors FPP and GGPP were unknown. These short-chain isoprenoids are critical in the post-translational modification of certain proteins which function as molecular switches in numerous signaling pathways. The major protein families belong to the superfamily of small GTPases, consisting of roughly 150 members. Recent experimental evidence indicated that members of the small GTPases are involved in AD pathogenesis and stimulated interest in the role of FPP and GGPP in protein prenylation and cell function. A straightforward prediction derived from those studies was that FPP and GGPP levels would be elevated in AD brains as compared with normal neurological controls. For the first time, recent evidence shows significantly elevated levels of FPP and GGPP in human AD brain tissue. Cholesterol levels did not differ between AD and control samples. One obvious conclusion is that homeostasis of FPP and GGPP but not of cholesterol is specifically targeted in AD. Since prenylation of small GTPases by FPP or GGPP is indispensable for their proper function we are proposing that these two isoprenoids are up-regulated in AD resulting in an over abundance of certain prenylated proteins which contributes to neuronal dysfunction.
Topics: Aging; Alzheimer Disease; Animals; Cholesterol; Humans; Metabolic Networks and Pathways; Mevalonic Acid; Models, Biological; Monomeric GTP-Binding Proteins; Nerve Degeneration; Protein Prenylation; Terpenes
PubMed: 20382260
DOI: 10.1016/j.bbalip.2010.03.014 -
Cell Communication and Signaling : CCS Aug 2022The CAAX-prenyltransferases farnesyltransferase (FTase) and geranylgeranyltransferase I (GGTase I) are heterodimers with a common α- (FTα) and unique β-subunits....
BACKGROUND
The CAAX-prenyltransferases farnesyltransferase (FTase) and geranylgeranyltransferase I (GGTase I) are heterodimers with a common α- (FTα) and unique β-subunits. Recently, α-subunits of species (e.g., human) that harbour an N-terminal proline-rich region (PRR) showed different dimerization behaviours than α-subunits without PRR (e.g., yeast). However, the specific function of the PRR has not been elucidated so far.
METHODS
To determine whether the PRR is a conserved motif throughout eukaryotes, we performed phylogenetics. Elucidating the impact of the PRR on enzyme properties, we cloned human as well as rat PRR deficient FTα, expressed them heterologously and compared protein-protein interaction by pull-down as well as crosslinking experiments. Substrate binding, enzyme activity and sensitivity towards common FTase inhibitors of full length and PRR-deletion α-subunits and their physiological partners was determined by continuous fluorescence assays.
RESULTS
The PRR is highly conserved in mammals, with an exception for marsupials harbouring a poly-alanine region instead. The PRR shows similarities to canonical SH3-binding domains and to profilin-binding domains. Independent of the PRR, the α-subunits were able to dimerize with the different physiological β-subunits in in vitro as well as in yeast two-hybrid experiments. FTase and GGTase I with truncated FTα were active. The K values for both substrates are in the single-digit µM range and show no significant differences between enzymes with full length and PRR deficient α-subunits within the species.
CONCLUSIONS
Our data demonstrate that an N-terminal PRR of FTα is highly conserved in mammals. We could show that the activity and inhibitability is not influenced by the truncation of the N-terminal region. Nevertheless, this region shows common binding motifs for other proteins involved in cell-signalling, trafficking and phosphorylation, suggesting that this PRR might have other or additional functions in mammals. Our results provide new starting points due to the relevant but only partly understood role of FTα in eukaryotic FTase and GGTase I. Video Abstract.
Topics: Animals; Dimethylallyltranstransferase; Humans; Mammals; Proline; Protein Prenylation; Rats; Saccharomyces cerevisiae; Substrate Specificity
PubMed: 35941619
DOI: 10.1186/s12964-022-00929-w -
British Journal of Pharmacology Mar 2003(1) Ajoene is a garlic compound with anti-platelet properties and, in addition, was shown to inhibit cholesterol biosynthesis by affecting 3-hydroxy-3-methyl-glutaryl...
(1) Ajoene is a garlic compound with anti-platelet properties and, in addition, was shown to inhibit cholesterol biosynthesis by affecting 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase and late enzymatic steps of the mevalonate (MVA) pathway. (2) MVA constitutes the precursor not only of cholesterol, but also of a number of non-sterol isoprenoids, such as farnesyl and geranylgeranyl groups. Covalent attachment of these MVA-derived isoprenoid groups (prenylation) is a required function of several proteins that regulate cell proliferation. We investigated the effect of ajoene on rat aortic smooth muscle cell proliferation as related to protein prenylation. (3) Cell counting, DNA synthesis, and cell cycle analysis showed that ajoene (1-50 micro M) interfered with the progression of the G1 phase of the cell cycle, and inhibited rat SMC proliferation. (4) Similar to the HMG-CoA reductase inhibitor simvastatin, ajoene inhibited cholesterol biosynthesis. However, in contrast to simvastatin, the antiproliferative effect of ajoene was not prevented by the addition of MVA, farnesol (FOH), and geranylgeraniol (GGOH). Labelling of smooth muscle cell cellular proteins with [3H]-FOH and [3H]-GGOH was significantly inhibited by ajoene. (5) In vitro assays for protein farnesyltransferase (PFTase) and protein geranylgeranyltransferase type I (PGGTase-I) confirmed that ajoene inhibits protein prenylation. High performance liquid chromatography (HPLC) and mass spectrometry analyses also demonstrated that ajoene causes a covalent modification of the cysteine SH group of a peptide substrate for protein PGGTase-I. (6) Altogether, our results provide evidence that ajoene interferes with the protein prenylation reaction, an effect that may contribute to its inhibition of SMC proliferation.
Topics: Animals; Aorta; Cell Division; Cells, Cultured; Disulfides; Dose-Response Relationship, Drug; Garlic; Growth Inhibitors; Male; Muscle, Smooth, Vascular; Plant Extracts; Protein Prenylation; Rats; Rats, Sprague-Dawley; Sulfoxides
PubMed: 12642382
DOI: 10.1038/sj.bjp.0705126 -
CaaX-motif-adjacent residues influence G protein gamma (Gγ) prenylation under suboptimal conditions.The Journal of Biological Chemistry Nov 2023Prenylation is an irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including...
Prenylation is an irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including migration, proliferation, and survival. Dysregulation of prenylation contributes to multiple disorders, including cancers and vascular and neurodegenerative diseases. Prenyltransferases tether isoprenoid lipids to proteins via a thioether linkage during prenylation. Pharmacological inhibition of the lipid synthesis pathway by statins is a therapeutic approach to control hyperlipidemia. Building on our previous finding that statins inhibit membrane association of G protein γ (Gγ) in a subtype-dependent manner, we investigated the molecular reasoning for this differential inhibition. We examined the prenylation of carboxy-terminus (Ct) mutated Gγ in cells exposed to Fluvastatin and prenyl transferase inhibitors and monitored the subcellular localization of fluorescently tagged Gγ subunits and their mutants using live-cell confocal imaging. Reversible optogenetic unmasking-masking of Ct residues was used to probe their contribution to prenylation and membrane interactions of the prenylated proteins. Our findings suggest that specific Ct residues regulate membrane interactions of the Gγ polypeptide, statin sensitivity, and extent of prenylation. Our results also show a few hydrophobic and charged residues at the Ct are crucial determinants of a protein's prenylation ability, especially under suboptimal conditions. Given the cell and tissue-specific expression of different Gγ subtypes, our findings indicate a plausible mechanism allowing for statins to differentially perturb heterotrimeric G protein signaling in cells depending on their Gγ-subtype composition. Our results may also provide molecular reasoning for repurposing statins as Ras oncogene inhibitors and the failure of using prenyltransferase inhibitors in cancer treatment.
Topics: Humans; Amino Acid Motifs; Drug Resistance; HeLa Cells; Heterotrimeric GTP-Binding Proteins; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Models, Molecular; Mutation; Protein Prenylation; Protein Structure, Tertiary; Protein Transport; Signal Transduction
PubMed: 37739036
DOI: 10.1016/j.jbc.2023.105269 -
World Journal of Gastroenterology Aug 2015Hepatitis D virus (HDV) is the smallest single stranded RNA virus infecting humans. The hepatitis B surface antigen envelope protein protects the HDV nucleocapsid... (Review)
Review
Hepatitis D virus (HDV) is the smallest single stranded RNA virus infecting humans. The hepatitis B surface antigen envelope protein protects the HDV nucleocapsid antigen and provides a means for the virus to enter and exit the hepatocyte. Hepatitis B and D viruses exploit the human sodium taurocholate co-transporting polypeptide (NTCP), a receptor, for their entry into hepatocytes. Prenylation of the large delta antigen is a critical determinant of HDV particle assembly. Treatment with pegylated interferon results in sustained virological response six months post-treatment in one fourth of the patients. Nucleos(t)ide analogs (NAs) have been widely tested in hepatitis delta, but they appear to be ineffective. Combination treatment of NAs with interferon also proved to be disappointing so there is a need for novel therapeutic options. The receptor function of NTCP is blocked by Myrcludex B, a synthetic N-acylated preS1 lipopeptide that competes with infectious virions for receptor binding. There are already some approved drugs available, including irbesartan, ezetimibe, and ritonavir and cyclosporin A, with documented inhibitory effects on NTCP's metabolic function. These drugs may have a role in HDV treatment. Interference with host-mediated post-translational changes of proteins that are crucial to the HDV life cycle, such as prenylation may become an important tool to control HDV infection and prevent replication. Lonafarnib, a prenylation inhibitor significantly reduces virus levels in hepatitis delta patients. Antisense oligodeoxynucleotides which are complementary to genomic HDV ribozyme self-cleavage site and stem I regions can inhibit genomic HDV ribozyme activity.
Topics: Antiviral Agents; Drug Therapy, Combination; Hepatitis D; Hepatitis Delta Virus; Host-Pathogen Interactions; Humans; Molecular Targeted Therapy; Oligonucleotides, Antisense; Protein Prenylation; Treatment Outcome; Virus Internalization
PubMed: 26327754
DOI: 10.3748/wjg.v21.i32.9461 -
Journal of Lipid Research Mar 2006Rab GTPases require special machinery for protein prenylation, which include Rab escort protein (REP) and Rab geranylgeranyl transferase (RGGT). The current model of Rab... (Review)
Review
Rab GTPases require special machinery for protein prenylation, which include Rab escort protein (REP) and Rab geranylgeranyl transferase (RGGT). The current model of Rab geranylgeranylation proposes that REP binds Rab and presents it to RGGT. After geranylgeranylation of Rab C-terminal cysteines, REP delivers the prenylated protein to membranes. The REP-like protein Rab GDP dissociation inhibitor (RabGDI) then recycles the prenylated Rab between the membrane and the cytosol. The recent solution of crystal structures of the Rab prenylation machinery has helped to refine this model and provided further insights. The hydrophobic prenyl binding pocket of RGGT and geranylgeranyl transferase type-I (GGT-I) differs from that of farnesyl transferase (FT). A bulky tryptophan residue in FT restricts the size of the pocket, whereas in RGGT and GGT-I, this position is occupied by smaller residues. A highly conserved phenylalanine in REP, which is absent in RabGDI, is critical for the formation of the REP:RGGT complex. Finally, a geranylgeranyl binding site conserved in REP and RabGDI has been identified within helical domain II. The postprenylation events, including the specific targeting of Rabs to target membranes and the requirement for single versus double geranylgeranylation by different Rabs, remain obscure and should be the subject of future studies.
Topics: Adaptor Proteins, Signal Transducing; Alkyl and Aryl Transferases; Amino Acid Sequence; Animals; Gene Expression Regulation; Guanine Nucleotide Dissociation Inhibitors; Humans; Lipids; Models, Biological; Molecular Sequence Data; Protein Prenylation; Protein Processing, Post-Translational; rab GTP-Binding Proteins
PubMed: 16401880
DOI: 10.1194/jlr.R500017-JLR200 -
Plant Signaling & Behavior Jul 2011Rho of Plants (ROP) small G proteins function at discrete domains of the plasma and possibly endo membranes. ROPs are synthesized as soluble proteins and their...
Rho of Plants (ROP) small G proteins function at discrete domains of the plasma and possibly endo membranes. ROPs are synthesized as soluble proteins and their attachment to membranes and partitioning in membrane microdomains are facilitated by the posttranslational lipid modifications prenylation and/or S-acylation. Based on their amino acid sequences, ROPs can be classified into two major subgroups: type-I ROPs terminate with a canonical CaaX box motif and are prenylated primarily by geranylgeranyltransferase-I (GGT-I) and to a lesser extent by farnesyltransferase (FT). Type-II ROPs terminate with a plant specific GC-CG box domain and are attached to the plasma membrane by stable S-acylation. In addition, type-I and possibly also type-II ROPs undergo activation dependent transient S-acylation in the G-domain and consequent partitioning into lipid rafts. Surprisingly, although geranylgeranylation is required for the membrane attachment of type-I ROPs and the γ subunits of heterotrimeric G proteins, Arabidopsis mutants lacking GGT-I function have a mild phenotype compared to wild type plants. The mild phenotype of the ggt-I mutants suggested that farnesylation by FT may compensate for the loss of GGT-I function and that possibly the prenylated type-I and S-acylated type-II ROPS have some overlapping functions. In a paper recently published in Plant Physiology we examined the role of the prenyl group type in type-I ROP function and membrane interaction dynamics and the functional redundancy between type-I and type-II ROPs. This study complements a second paper in which we examined the role of G-domain transient S-acylation in the membrane interaction dynamics and signaling by type-I ROPs. Together these two studies provide a framework for realizing the role of prenylation and S-acylation in subcellular targeting, membrane interaction dynamics and signaling by ROP GTPases.
Topics: Acylation; Arabidopsis; Arabidopsis Proteins; Monomeric GTP-Binding Proteins; Plant Proteins; Protein Prenylation
PubMed: 21694496
DOI: 10.4161/psb.6.7.15578 -
The Journal of Pathology Mar 2022Investigations of major mevalonate pathway enzymes have demonstrated the importance of local isoprenoid synthesis in cardiac homeostasis. Farnesyl diphosphate synthase...
Investigations of major mevalonate pathway enzymes have demonstrated the importance of local isoprenoid synthesis in cardiac homeostasis. Farnesyl diphosphate synthase (FPPS) synthesizes isoprenoid precursors needed for cholesterol biosynthesis and protein prenylation. Wang, Zhang, Chen et al, in a recently published article in The Journal of Pathology, elegantly elucidated the pathological outcomes of FPPS deficiency in cardiomyocytes, which paradoxically resulted in increased prenylation of the small GTPases Ras and Rheb. Cardiomyocyte FPPS depletion caused severe dilated cardiomyopathy that was associated with enhanced GTP-loading and abundance of Ras and Rheb in lipidated protein-enriched cardiac fractions and robust activation of downstream hypertrophic ERK1/2 and mTOR signaling pathways. Cardiomyopathy and activation of ERK1/2 and mTOR caused by loss of FPPS were ameliorated by inhibition of farnesyltransferase, suggesting that impairment of FPPS activity results in promiscuous activation of Ras and Rheb through non-canonical actions of farnesyltransferase. Here, we discuss the findings and adaptive signaling mechanisms in response to disruption of local cardiomyocyte mevalonate pathway activity, highlighting how alteration in a key branch point in the mevalonate pathway affects cardiac biology and function and perturbs protein prenylation, which might unveil novel strategies and intricacies of targeting the mevalonate pathway to treat cardiovascular diseases. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Topics: Heart Failure; Humans; Mevalonic Acid; Monomeric GTP-Binding Proteins; Myocytes, Cardiac; Prenylation; Protein Prenylation
PubMed: 34783037
DOI: 10.1002/path.5837