Geranylgeranyl pyrophosphate-mediated protein geranylgeranylation regulates endothelial cell proliferation and apoptosis during vasculogenesis in mouse embryo

Vascular development is essential for the establishment of the circulatory system during embryonic development and requires the proliferation of endothelial cells.However,the underpinning regulatory mechanisms are not well understood.Here,we report that geranylgeranyl pyrophosphate(GGPP),a metabolite involved in protein geranylgeranylation,plays an indispensable role in embryonic vascular development.GGPP is synthesized by geranylgeranyl pyrophosphate synthase(GGPPS)in the mevalonate pathway.The selective knockout of Ggpps in endothelial cells led to aberrant vascular development and embryonic lethality,resulting from the decreased proliferation and enhanced apoptosis of endothelial cells during vasculogenesis.The defect in protein geranylgeranylation induced by GGPP depletion inhibited the membrane localization of Rho A and enhanced yes-associated protein(YAP)phosphorylation,thereby prohibiting the entry of YAP into the nucleus and the expression of YAP target genes related to cell proliferation and the antiapoptosis process.Moreover,inhibition of the mevalonate pathway by simvastatin induced endothelial cell proliferation defects and apoptosis,which were ameliorated by GGPP.Geranylgeraniol(GGOH),a precursor of GGPP,ameliorated the harmful effects of simvastatin on vascular development of developing fetuses in pregnant mice.These results indicate that GGPP-mediated protein geranylgeranylation is essential for endothelial cell proliferation and the antiapoptosis process during embryonic vascular development.

A rice geranylgeranyl reductase is essential for chloroplast development

Chloroplasts are essential for plant photosynthesis and growth.Many genes have been identified that regulate plant chloroplast development.However,it is not known at a molecular level how these genes regulate chloroplast biogenesis.In this study,we isolated a mutant ygl2(yellow-green leaf2)that exhibited a pigment-defective phenotype.YGL2 encodes a geranylgeranyl reductase,and in mutant ygl2,there was a single base change(T1361G)located in the third exon of YGL2 that resulted in a missense mutation(L454R)in the encoded product.Transmission electron microscopy revealed that chloroplast development was impaired in the ygl2 mutant.The expression levels of plastid-encoded genes were significantly altered in the ygl2 mutant.Furthermore,in a yeast two-hybrid assay,we found that YGL2 interacted with the RNA editing factor MORF8.

Cloning And Characterization Of A Geranylgeranyl Diphosphate Synthase Gene From Taxus Chinensis

Taxol(Paclitaxel)is a diterpene from Taxus species and has been used in treatment of various kinds of cancers.Geranylgeranyl diphosphate synthase(GGPPS)catalyzes the formation of geranylgeranyl diphosphate(GGPP,the common precursor for diterpenes and plays a key role in taxol biosynthesis.Here we report a functional GGPPS gene from Taxus chinensis(designated TcGGPPS).TcGGPPS is an intron free gene and has a 1,182-bp open reading frame encoding a polypeptide of 393 amino acid residues with a calculated molecular mass of 42.63 kDa and an isoelectric point of 5.58.The catalytic activity of TcGGPPS for production of GGPP was verified by a color enhancement assay in the Escherichia coli cells harboring plasmid pAC-BETA.Multiple sequence alignment indicates that TcGGPPS is a little different in sequence from the functional GGPPS genes from other Taxus species such as T.canadensis,T.media and T.wallichiana,which are almost identical to each other.Protein structure prediction by using bioinformatics reveals that TcGGPPS consists of 52.2%α-helix,10.9%extended strand,8.4%β-turn and 28.5%random coil,and has a three-dimensional structure highly similar to the structurally known Sinapis alba GGPPS.In silicon predictions also demonstrate that TcGGPPS has a plastid-targeting peptide at the N-terminus,suggesting it is responsible for the synthesis of GGPP in plastids.

Heteromerization of short-chain trans-prenyltransferase controls precursor allocation within a plastidial terpenoid network

Terpenes are the largest and most diverse class of plant specialized metabolites.Sesterterpenes(C25),which are derived from the plastid methylerythritol phosphate pathway,were recently characterized in plants.In Arabidopsis thaliana,four genes encoding geranylfarnesyl diphosphate synthase(GFPPS)(AtGFPPS1 to 4)are responsible for the production of GFPP,which is the common precursor for sesterterpene biosynthesis.However,the interplay between sesterterpenes and other known terpenes remain elusive.Here,we first provide genetic evidence to demonstrate that GFPPSs are responsible for sesterterpene production in Arabidopsis.Blockage of the sesterterpene pathway at the GFPPS step increased the production of geranylgeranyl diphosphate(GGPP)-derived terpenes.Interestingly,co-expression of sester TPSs in GFPPSOE(overexpression)plants rescued the phenotypic changes of GFPPS-OE plants by restoring the endogenous GGPP.We further demonstrated that,in addition to precursor(DMAPP/IPP)competition by GFPPS and GGPP synthase(GGPPS)in plastids,GFPPS directly decreased the activity of GGPPS through protein-protein interaction,ultimately leading to GGPP deficiency in planta.Our study provides a new regulatory mechanism of the plastidial terpenoid network in plant cells.

Cholesterol metabolic enzyme Ggpps regulates epicardium development and ventricular wall architecture integrity in mice

During embryonic heart development,the progenitor cells in the epicardium would migrate and differentiate into noncardiomyocytes in myocardium and affect the integrity of ventricular wall,but the underlying mechanism has not been well studied.We have found that myocardium geranylgeranyl diphosphate synthase(Ggpps),a metabolic enzyme for cholesterol biosynthesis,is critical for cardiac cytoarchitecture remodelling during heart development.Here,we further reveal that epicardial Ggpps could also regulate ventricular wall architecture integrity.Epicardium-specific deletion of Ggpps before embryonic day 10.5(E10.5)is embryonic lethal,whereas after E13.5 is survival but with defects in the epicardium and ventricular wall structure.Ggpps deficiency in the epicardium enhances the proliferation of epicardial cells and disrupts cell‒cell contact,which makes epicardial cells easier to invade into ventricular wall.Thus,the fibroblast proliferation and coronary formation in myocardium were found enhanced that might disturb the coronary vasculature remodelling and ventricular wall integrity.These processes might be associated with the activation of YAP signalling,whose nuclear distribution is blocked by Ggpps deletion.In conclusion,our findings reveal a potential link between the cholesterol metabolism and heart epicardium and myocardium development in mammals,which might provide a new view of the cause for congenital heart diseases and potential therapeutic target in pathological cardiac conditions.

Plant geranylgeranyl diphosphate synthases: every (gene) family has a story

Plant isoprenoids(also known as terpenes or terpenoids)are a wide family of primary and secondary metabolites with multiple functions.In particular,most photosynthesis-related isoprenoids(including carotenoids and chlorophylls)as well as diterpenes and polyterpenes derive from geranylgeranyl diphosphate(GGPP)produced by GGPP synthase(GGPPS)enzymes in several cell compartments.Plant genomes typically harbor multiple copies of differentially expressed genes encoding GGPPS-like pro-teins.While sequence comparisons allow to identify potential GGPPS candidates,experimental evidence is required to ascertain their enzymatic activity and biologi cal function.Actually,functional analyses of the full set of potential GGPPS paralogs are only available for a handful of plant species.Here we review our current knowledge on the GGPPS families of the model plant Arabidopsis thaliana and the crop species rice(0ryza sativa),pepper(Capsicum annuum)and tomato(Solanum lycopersicum).The results indicate that a major determinant of the biological role of particular GGPPS paralogs is the expression profile of the corresponding genes even though specific interactions with other proteins(including GGPP-consuming enzymes)might also contribute to subfunctionalization.In some species,however,a single GGPPS isoforms appears to be responsible for the production of most if not all GGPP required for cell functions.Deciphering the mechanisms regulating GGPPS activity in particular cell compartments,tissues,organs and plant species will be very useful for future metabolic engineering approaches aimed to manipulate the accumulation of particular GGPP-derived products of interest without negatively impacting the levels of other isoprenoids required to sustain essential cell functions.

cDNA cloning, chromosome mapping and expression characterization of human geranylgeranyl pyrophosphate synthase

Geranylgeranyl pyrophosphate (GGPP) mainly participates in post-translational modification for various proteins including Rho/Rac, Rap and Rab families, as well as in regulation for cell apoptosis. Geranylgeranyl pyrophosphate synthase (GGPPS), which catalyzes the condensation reaction between farnesyl diphosphate and isopentenyl diphosphate, is the key enzyme for synthesizing GGPP. We report the isolation of a gene transcript showing high homology with Drosophila GGPPS cDNA. The transcript is 1 466 bp in length and contains an intact open reading frame (ORF) ranging from nt 239 to 1 138. This ORF encodes a deduced protein of 300 residues with calculated molecular weight of 35 ku. The deduced protein shows 57.5% identity and 75% similarity with Drosophila GGPPS, and contains five characteristic domains of prenyltransferases. Northern hybridization revealed that human GGPPS was expressed highest in heart, and moderately in spleen, testis, brain, placenta, lung, liver, skeletal muscle, kidney and

Old and new damage‐associated molecular patterns (DAMPs) in autoimmune diseases

All organisms living in complex environments have evolved effective mechanisms of dynamic responses to extracellular stimuli.The immune system activates when damaged or injured cells release damage‐associated molecular patterns(DAMPs).In addition to well‐characterized DAMPs such as high‐mobility group box 1 and adenosine triphosphate,studies on new classes of DAMPs have emerged.Here,we review recent reports of a new class of isoprenoid‐derived DAMPs,including farnesyl pyrophosphate and geranylgeranyl pyrophosphate,both of which are pivotal metabolic inter-mediates of the mevalonate pathway.We also explore the roles of old and new DAMPs in autoimmune diseases that result from dysregulated inflammation.The findings highlight that understanding the functional mechanisms of DAMPs is important to enrich the DAMP family and decipher their immunoregulatory mechanisms to provide new therapeutics for the prevention and treatment of autoimmune diseases.