-
Developmental Cell Jun 2020Compartmentalized signaling is critical for cellular organization and specificity of functional outcomes in neurons. Here, we report that post-translational lipidation...
Compartmentalized signaling is critical for cellular organization and specificity of functional outcomes in neurons. Here, we report that post-translational lipidation of newly synthesized proteins in axonal compartments allows for short-term and autonomous responses to extrinsic cues. Using conditional mutant mice, we found that protein prenylation is essential for sympathetic axon innervation of target organs. We identify a localized requirement for prenylation in sympathetic axons to promote axonal growth in response to the neurotrophin, nerve growth factor (NGF). NGF triggers prenylation of proteins including the Rac1 GTPase in axons, counter to the canonical view of prenylation as constitutive, and strikingly, in a manner dependent on axonal protein synthesis. Newly prenylated proteins localize to TrkA-harboring endosomes in axons and promote receptor trafficking necessary for axonal growth. Thus, coupling of prenylation to local protein synthesis presents a mechanism for spatially segregated cellular functions during neuronal development.
Topics: Animals; Axon Guidance; Axons; Cells, Cultured; Endosomes; HEK293 Cells; Humans; Mice; Mice, Inbred C57BL; Nerve Growth Factor; Neuropeptides; PC12 Cells; Protein Prenylation; Rats; Rats, Sprague-Dawley; Receptor, trkA; rac1 GTP-Binding Protein
PubMed: 32533921
DOI: 10.1016/j.devcel.2020.05.020 -
BioRxiv : the Preprint Server For... Sep 2023The C-terminal CaaX sequence (cysteine-aliphatic-aliphatic-any of several amino acids) is subject to isoprenylation on the conserved cysteine and is estimated to occur...
The C-terminal CaaX sequence (cysteine-aliphatic-aliphatic-any of several amino acids) is subject to isoprenylation on the conserved cysteine and is estimated to occur in 1-2% of proteins within yeast and human proteomes. Recently, non-canonical CaaX sequences in addition to shorter and longer length CaX and CaaaX sequences have been identified that can be prenylated. Much of the characterization of prenyltransferases has relied on the yeast system because of its genetic tractability and availability of reporter proteins, such as the -factor mating pheromone, Ras GTPase, and Ydj1 Hsp40 chaperone. To compare the properties of yeast and human prenyltransferases, including the recently expanded target specificity of yeast farnesyltransferase, we have developed yeast strains that express human farnesyltransferase or geranylgeranyltransferase-I in lieu of their yeast counterparts. The humanized yeast strains display robust prenyltransferase activity that functionally replaces yeast prenyltransferase activity in a wide array of tests, including the prenylation of a wide variety of canonical and non-canonical human CaaX sequences, virus encoded CaaX sequences, non-canonical length sequences, and heterologously expressed human proteins HRas and DNAJA2. These results reveal highly overlapping substrate specificity for yeast and human farnesyltransferase, and mostly overlapping substrate specificity for GGTase-I. This yeast system is a valuable tool for further defining the prenylome of humans and other organisms, identifying proteins for which prenylation status has not yet been determined.
PubMed: 37786692
DOI: 10.1101/2023.09.19.558494 -
Bioorganic & Medicinal Chemistry Letters Oct 2019The enzyme geranylgeranyl diphosphate synthase (GGDPS) is a potential therapeutic target for multiple myeloma. Malignant plasma cells produce and secrete large amounts...
The enzyme geranylgeranyl diphosphate synthase (GGDPS) is a potential therapeutic target for multiple myeloma. Malignant plasma cells produce and secrete large amounts of monoclonal protein, and inhibition of GGDPS results in disruption of protein geranylgeranylation which in turn impairs intracellular protein trafficking. Our previous work has demonstrated that some isoprenoid triazole bisphosphonates are potent and selective inhibitors of GGDPS. To explore the possibility of selective delivery of such compounds to plasma cells, new analogues with an ω-hydroxy group have been synthesized and examined for their enzymatic and cellular activity. These studies demonstrate that incorporation of the ω-hydroxy group minimally impairs GGDPS inhibitory activity. Furthermore conjugation of one of the novel ω-hydroxy GGDPS inhibitors to hyaluronic acid resulted in enhanced cellular activity. These results will allow future studies to focus on the in vivo biodistribution of HA-conjugated GGDPS inhibitors.
Topics: Antineoplastic Agents; Apoptosis; Cell Proliferation; Diphosphonates; Enzyme Inhibitors; Farnesyltranstransferase; Humans; Models, Molecular; Molecular Structure; Multiple Myeloma; Protein Prenylation; Structure-Activity Relationship; Terpenes; Tumor Cells, Cultured
PubMed: 31474482
DOI: 10.1016/j.bmcl.2019.126633 -
Nature Communications Sep 2019Rho family proteins are prenylated by geranylgeranyltransferase type I (GGTase-I), which normally target proteins to membranes for GTP-loading. However, conditional...
Rho family proteins are prenylated by geranylgeranyltransferase type I (GGTase-I), which normally target proteins to membranes for GTP-loading. However, conditional deletion of GGTase-I in mouse macrophages increases GTP-loading of Rho proteins, leading to enhanced inflammatory responses and severe rheumatoid arthritis. Here we show that heterozygous deletion of the Rho family gene Rac1, but not Rhoa and Cdc42, reverses inflammation and arthritis in GGTase-I-deficient mice. Non-prenylated Rac1 has a high affinity for the adaptor protein Ras GTPase-activating-like protein 1 (Iqgap1), which facilitates both GTP exchange and ubiquitination-mediated degradation of Rac1. Consistently, inactivating Iqgap1 normalizes Rac1 GTP-loading, and reduces inflammation and arthritis in GGTase-I-deficient mice, as well as prevents statins from increasing Rac1 GTP-loading and cytokine production in macrophages. We conclude that blocking prenylation stimulates Rac1 effector interactions and unleashes proinflammatory signaling. Our results thus suggest that prenylation normally restrains innate immune responses by preventing Rac1 effector interactions.
Topics: Alkyl and Aryl Transferases; Animals; Cytokines; Immunity, Innate; Macrophages; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Protein Binding; Protein Prenylation; RAW 264.7 Cells; Signal Transduction; rac1 GTP-Binding Protein; ras GTPase-Activating Proteins
PubMed: 31484924
DOI: 10.1038/s41467-019-11606-x -
Membranes Dec 2022The membranes of plant cells are dynamic structures composed of phospholipids and proteins. Proteins harboring phospholipid-binding domains or lipid ligands can localize... (Review)
Review
The membranes of plant cells are dynamic structures composed of phospholipids and proteins. Proteins harboring phospholipid-binding domains or lipid ligands can localize to membranes. Stress perception can alter the subcellular localization of these proteins dynamically, causing them to either associate with or detach from membranes. The mechanisms behind the re-localization involve changes in the lipidation state of the proteins and interactions with membrane-associated biomolecules. The functional significance of such re-localization includes the regulation of molecular transport, cell integrity, protein folding, signaling, and gene expression. In this review, proteins that re-localize to or away from membranes upon abiotic and biotic stresses will be discussed in terms of the mechanisms involved and the functional significance of their re-localization. Knowledge of the re-localization mechanisms will facilitate research on increasing plant stress adaptability, while the study on re-localization of proteins upon stresses will further our understanding of stress adaptation strategies in plants.
PubMed: 36557168
DOI: 10.3390/membranes12121261 -
Cancer Drug Resistance (Alhambra,... 2023This study aimed to decipher the molecular mechanism underlying the synergistic effect of inhibitors of the mevalonate-cholesterol pathway (i.e., statins) and...
This study aimed to decipher the molecular mechanism underlying the synergistic effect of inhibitors of the mevalonate-cholesterol pathway (i.e., statins) and aminopeptidase inhibitors (APis) on APi-sensitive and -resistant acute myeloid leukemia (AML) cells. U937 cells and their sublines with low and high levels of acquired resistance to (6S)-[(R)-2-((S)-Hydroxy-hydroxycarbamoyl-methoxy-methyl)-4-methyl-pentanoylamino]-3,3 dimethyl-butyric acid cyclopentyl ester (CHR2863), an APi prodrug, served as main AML cell line models. Drug combination effects were assessed with CHR2863 and non-toxic concentrations of various statins upon cell growth inhibition, cell cycle effects, and apoptosis induction. Mechanistic studies involved analysis of Rheb prenylation required for mTOR activation. A strong synergy of CHR2863 with the statins simvastatin, fluvastatin, lovastatin, and pravastatin was demonstrated in U937 cells and two CHR2863-resistant sublines. This potent synergy between simvastatin and CHR2863 was also observed with a series of other human AML cell lines (e.g., THP1, MV4-11, and KG1), but not with acute lymphocytic leukemia or multiple solid tumor cell lines. This synergistic activity was: (i) specific for APis (e.g., CHR2863 and Bestatin), rather than for other cytotoxic agents; and (ii) corroborated by enhanced induction of apoptosis and cell cycle arrest which increased the sub-G1 fraction. Consistently, statin potentiation of CHR2863 activity was abrogated by co-administration of mevalonate and/or farnesyl pyrophosphate, suggesting the involvement of protein prenylation; this was experimentally confirmed by impaired Rheb prenylation by simvastatin. These novel findings suggest that the combined inhibitory effect of impaired Rheb prenylation and CHR2863-dependent mTOR inhibition instigates a potent synergistic inhibition of statins and APis on human AML cells.
PubMed: 37842233
DOI: 10.20517/cdr.2023.20 -
Geranylgeranyl diphosphate synthase: Role in human health, disease and potential therapeutic target.Clinical and Translational Medicine Jan 2023Geranylgeranyl diphosphate synthase (GGDPS), an enzyme in the isoprenoid biosynthesis pathway, is responsible for the production of geranylgeranyl pyrophosphate (GGPP).... (Review)
Review
Geranylgeranyl diphosphate synthase (GGDPS), an enzyme in the isoprenoid biosynthesis pathway, is responsible for the production of geranylgeranyl pyrophosphate (GGPP). GGPP serves as a substrate for the post-translational modification (geranylgeranylation) of proteins, including those belonging to the Ras superfamily of small GTPases. These proteins play key roles in signalling pathways, cytoskeletal regulation and intracellular transport, and in the absence of the prenylation modification, cannot properly localise and function. Aberrant expression of GGDPS has been implicated in various human pathologies, including liver disease, type 2 diabetes, pulmonary disease and malignancy. Thus, this enzyme is of particular interest from a therapeutic perspective. Here, we review the physiological function of GGDPS as well as its role in pathophysiological processes. We discuss the current GGDPS inhibitors under development and the therapeutic implications of targeting this enzyme.
Topics: Humans; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Farnesyltranstransferase; Polyisoprenyl Phosphates
PubMed: 36650113
DOI: 10.1002/ctm2.1167 -
Translational Vision Science &... Jul 2021Choroideremia results from the deficiency of Rab Escort Protein 1 (REP1), encoded by CHM, involved in the prenylation of Rab GTPases. Here, we investigate whether the...
PURPOSE
Choroideremia results from the deficiency of Rab Escort Protein 1 (REP1), encoded by CHM, involved in the prenylation of Rab GTPases. Here, we investigate whether the transcription and expression of other genes involved in the prenylation of Rab proteins correlates with disease progression in a cohort of patients with choroideremia.
METHODS
Rates of retinal pigment epithelial area loss in 41 patients with choroideremia were measured using fundus autofluorescence imaging for up to 4 years. From lysates of cultured skin fibroblasts donated by patients (n = 15) and controls (n = 14), CHM, CHML, RABGGTB and RAB27A mRNA expression, and REP1 and REP2 protein expression were compared.
RESULTS
The central autofluorescent island area loss in patients with choroideremia occurred with a mean half-life of 5.89 years (95% confidence interval [CI] = 5.09-6.70), with some patients demonstrating relatively fast or slow rates of progression (range = 3.3-14.1 years). Expression of CHM mRNA and REP1 protein were significantly decreased in all patients. No difference in expression of CHML, RABGGTB, RAB27A, or REP2 was seen between patients and controls. No correlation was seen between expression of the genes analyzed and rates of retinal degeneration. Non-sense induced transcriptional compensation of CHML, a CHM-like retrogene, was not observed in patients with CHM variants predicted to undergo non-sense mediated decay.
CONCLUSIONS
Patients with choroideremia, who are deficient for REP1, show normal levels of expression of other genes involved in Rab prenylation, which do not appear to play any modifying role in the rate of disease progression.
TRANSLATIONAL RELEVANCE
There remains little evidence for selection of patients for choroideremia gene therapy based on genotype.
Topics: Adaptor Proteins, Signal Transducing; Choroideremia; Disease Progression; Humans; Prenylation; Retinal Degeneration
PubMed: 34254989
DOI: 10.1167/tvst.10.8.12 -
Translational Psychiatry Jan 2020The pathophysiology of schizophrenia includes altered neurotransmission, dysregulated intracellular signaling pathway activity, and abnormal dendritic morphology that...
The pathophysiology of schizophrenia includes altered neurotransmission, dysregulated intracellular signaling pathway activity, and abnormal dendritic morphology that contribute to deficits of synaptic plasticity in the disorder. These processes all require dynamic protein-protein interactions at cell membranes. Lipid modifications target proteins to membranes by increasing substrate hydrophobicity by the addition of a fatty acid or isoprenyl moiety, and recent evidence suggests that dysregulated posttranslational lipid modifications may play a role in multiple neuropsychiatric disorders, including schizophrenia. Consistent with these emerging findings, we have recently reported decreased protein S-palmitoylation in schizophrenia. Protein prenylation is a lipid modification that occurs upstream of S-palmitoylation on many protein substrates, facilitating membrane localization and activity of key intracellular signaling proteins. Accordingly, we hypothesized that, in addition to palmitoylation, protein prenylation may be abnormal in schizophrenia. To test this, we assayed protein expression of the five prenyltransferase subunits (FNTA, FNTB, PGGT1B, RABGGTA, and RABGGTB) in postmortem dorsolateral prefrontal cortex from patients with schizophrenia and paired comparison subjects (n = 13 pairs). We found decreased levels of FNTA (14%), PGGT1B (13%), and RABGGTB (8%) in schizophrenia. To determine whether upstream or downstream factors may be driving these changes, we also assayed protein expression of the isoprenoid synthases FDPS and GGPS1 and prenylation-dependent processing enzymes RCE and ICMT. We found these upstream and downstream enzymes to have normal protein expression. To rule out effects from chronic antipsychotic treatment, we assayed FNTA, PGGT1B, and RABGGTB in the cortex from rats treated long-term with haloperidol decanoate and found no change in the expression of these proteins. Given the role prenylation plays in localization of key signaling proteins found at the synapse, these data offer a potential mechanism underlying abnormal protein-protein interactions and protein localization in schizophrenia.
Topics: Animals; Antipsychotic Agents; Dimethylallyltranstransferase; Humans; Intracellular Signaling Peptides and Proteins; Prefrontal Cortex; Rats; Schizophrenia
PubMed: 32066669
DOI: 10.1038/s41398-019-0610-7 -
Disease Models & Mechanisms May 2024Prenylated proteins are prevalent in eukaryotic biology (∼1-2% of proteins) and are associated with human disease, including cancer, premature aging and infections....
Prenylated proteins are prevalent in eukaryotic biology (∼1-2% of proteins) and are associated with human disease, including cancer, premature aging and infections. Prenylated proteins with a C-terminal CaaX sequence are targeted by CaaX-type prenyltransferases and proteases. To aid investigations of these enzymes and their targets, we developed Saccharomyces cerevisiae strains that express these human enzymes instead of their yeast counterparts. These strains were developed in part to explore human prenyltransferase specificity because of findings that yeast FTase has expanded specificity for sequences deviating from the CaaX consensus (i.e. atypical sequence and length). The humanized yeast strains displayed robust prenyltransferase activity against CaaX sequences derived from human and pathogen proteins containing typical and atypical CaaX sequences. The system also recapitulated prenylation of heterologously expressed human proteins (i.e. HRas and DNAJA2). These results reveal that substrate specificity is conserved for yeast and human farnesyltransferases but is less conserved for type I geranylgeranyltransferases. These yeast systems can be easily adapted for investigating the prenylomes of other organisms and are valuable new tools for helping define the human prenylome, which includes physiologically important proteins for which the CaaX modification status is unknown.
Topics: Humans; Saccharomyces cerevisiae; Protein Prenylation; Substrate Specificity; Amino Acid Sequence; Dimethylallyltranstransferase; Viral Proteins; Alkyl and Aryl Transferases
PubMed: 38818856
DOI: 10.1242/dmm.050516