Altering potato isoprenoid metabolism increases biomass and induces early flowering

2020 ◽  
Vol 71 (14) ◽  
pp. 4109-4124
Author(s):  
Moehninsi ◽  
Iris Lange ◽  
B Markus Lange ◽  
Duroy A Navarre
Keyword(s):  
Metabolic Regulation ◽  
Transcriptional Control ◽  
Mevalonate Pathway ◽  
Early Flowering ◽  
Bioenergy Crops ◽  
Isoprenoid Metabolism ◽  
Transgenic Lines ◽  
Coa Reductase ◽  
Rate Limiting

Abstract Isoprenoids constitute the largest class of plant natural products and have diverse biological functions including in plant growth and development. In potato (Solanum tuberosum), the regulatory mechanism underlying the biosynthesis of isoprenoids through the mevalonate pathway is unclear. We assessed the role of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) homologs in potato development and in the metabolic regulation of isoprenoid biosynthesis by generating transgenic lines with down-regulated expression (RNAi-hmgr) or overexpression (OE) of one (StHMGR1 or StHMGR3) or two genes, HMGR and farnesyl diphosphate synthase (FPS; StHMGR1/StFPS1 or StHMGR3/StFPS1). Levels of sterols, steroidal glycoalkaloids (SGAs), and plastidial isoprenoids were elevated in the OE-HMGR1, OE-HMGR1/FPS1, and OE-HMGR3/FPS1 lines, and these plants exhibited early flowering, increased stem height, increased biomass, and increased total tuber weight. However, OE-HMGR3 lines showed dwarfism and had the highest sterol amounts, but without an increase in SGA levels, supporting a rate-limiting role for HMGR3 in the accumulation of sterols. Potato RNAi-hmgr lines showed inhibited growth and reduced cytosolic isoprenoid levels. We also determined the relative importance of transcriptional control at regulatory points of isoprenoid precursor biosynthesis by assessing gene–metabolite correlations. These findings provide novel insights into specific end-products of the sterol pathway and could be important for crop yield and bioenergy crops.

scholarly journals Depletion of essential isoprenoids and ER stress induction following acute liver-specific deletion of HMG-CoA reductase

2020 ◽  
Vol 61 (12) ◽  
pp. 1675-1686
Author(s):  
Marco De Giorgi ◽  
Kelsey E. Jarrett ◽  
Jason C. Burton ◽  
Alexandria M. Doerfler ◽  
Ayrea Hurley ◽  
...  
Keyword(s):  
Er Stress ◽  
Mevalonate Pathway ◽  
Critical Role ◽  
Cellular Level ◽  
Hmg Coa Reductase ◽  
Biochemical Level ◽  
Genetic Deletion ◽  
Coa Reductase ◽  
Rate Limiting ◽  
Specific Deletion

HMG-CoA reductase (Hmgcr) is the rate-limiting enzyme in the mevalonate pathway and is inhibited by statins. In addition to cholesterol, Hmgcr activity is also required for synthesizing nonsterol isoprenoids, such as dolichol, ubiquinone, and farnesylated and geranylgeranylated proteins. Here, we investigated the effects of Hmgcr inhibition on nonsterol isoprenoids in the liver. We have generated new genetic models to acutely delete genes in the mevalonate pathway in the liver using AAV-mediated delivery of Cre-recombinase (AAV-Cre) or CRISPR/Cas9 (AAV-CRISPR). The genetic deletion of Hmgcr by AAV-Cre resulted in extensive hepatocyte apoptosis and compensatory liver regeneration. At the biochemical level, we observed decreased levels of sterols and depletion of the nonsterol isoprenoids, dolichol and ubiquinone. At the cellular level, Hmgcr-null hepatocytes showed ER stress and impaired N-glycosylation. We further hypothesized that the depletion of dolichol, essential for N-glycosylation, could be responsible for ER stress. Using AAV-CRISPR, we somatically disrupted dehydrodolichyl diphosphate synthase subunit (Dhdds), encoding a branch point enzyme required for dolichol biosynthesis. Dhdds-null livers showed ER stress and impaired N-glycosylation, along with apoptosis and regeneration. Finally, the combined deletion of Hmgcr and Dhdds synergistically exacerbated hepatocyte ER stress. Our data show a critical role for mevalonate-derived dolichol in the liver and suggest that dolichol depletion is at least partially responsible for ER stress and apoptosis upon potent Hmgcr inhibition.

Role of the Mevalonate Pathway in Adrenocortical Tumorigenesis

2020 ◽  
Author(s):  
Helena Panteliou Lima-Valassi ◽  
Antonio Marcondes Lerario ◽  
Luciana Ribeiro Montenegro ◽  
Maria Candida Barisson Villares Fragoso ◽  
Madson Queiroz Almeida ◽  
...  
Keyword(s):  
Cell Viability ◽  
Mevalonate Pathway ◽  
Colorimetric Assay ◽  
Rt Pcr ◽  
Expression Of Genes ◽  
Pathway Inhibition ◽  
Key Steps ◽  
Cell Growth And Proliferation ◽  
Rate Limiting

Abstract3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is the rate-limiting enzyme of the mevalonate pathway, which generates cholesterol and non-sterol compounds such as isoprenoid, which are involved in key steps of tumorigenesis such as cell growth and proliferation. Our aim was to evaluate the role of the mevalonate pathway in adrenocortical tumors (ACTs). Expression pattern of HMGCR, FDFT1, LDLR, SCARB1, StAR, TSPO, CYP11A1, CYP11B1, CYP17A1, CYP21A1, and HSD3B1 genes, involved in the mevalonate pathway and steroidogenesis, was quantified by real-time RT-PCR in 46 ACT [14 adenomas (ACA) and 11 carcinomas (ACC) from adults and 13 ACA and 8 ACC from pediatric patients]. Effects of the mevalonate pathway inhibition on NCI-H295A cell viability was assessed by colorimetric assay. HMGCR was overexpressed in most adult ACT. The expression of TSPO, STAR, CYP11B1, CYP21A1, and HSD3B1 in adult ACC was significantly lower than in ACA (p<0.05). Regarding pediatric ACT, the expression of genes involved in steroidogenesis was not different between ACA and ACC. Inhibition of isoprenoid production significantly decreased the viability of NCI-H295A cells (p<0.05). However, cholesterol synthesis blockage did not show the same effect on cell viability. Low expression of TSPO , StAR, CYP11B1, CYP21A1, and HSD3B1 characterized a signature of adult ACCs. Our data suggest that HMGCR overexpression in adult ACC might lead to intracellular isoprenoid accumulation and cell proliferation. Therefore, the mevalonate pathway is a potential target for ACC treatment.

scholarly journals Human T Cell Receptor γδ Cells Recognize Endogenous Mevalonate Metabolites in Tumor Cells

2003 ◽  
Vol 197 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Hans-Jürgen Gober ◽  
Magdalena Kistowska ◽  
Lena Angman ◽  
Paul Jenö ◽  
Lucia Mori ◽  
...  
Keyword(s):  
T Cell ◽  
Tumor Cells ◽  
T Cell Receptor ◽  
Mevalonate Pathway ◽  
Cell Receptor ◽  
Danger Signal ◽  
Human T Cell ◽  
Novel Target ◽  
Coa Reductase ◽  
Rate Limiting

T lymphocytes expressing the T cell receptor (TCR)-γδ recognize unknown antigens on tumor cells. Here we identify metabolites of the mevalonate pathway as the tumor ligands that activate TCR-γδ cells. In tumor cells, blockade of hydroxy-methylglutaryl-CoA reductase (HMGR), the rate limiting enzyme of the mevalonate pathway, prevents both accumulation of mevalonate metabolites and recognition by TCR-γδ cells. When metabolite accumulation is induced by overexpressing HMGR or by treatment with nitrogen-containing bisphosphonate drugs, tumor cells derived from many tissues acquire the capacity to stimulate the same TCR-γδ population. Accumulation of mevalonate metabolites in tumor cells is a powerful danger signal that activates the immune response and may represent a novel target of tumor immunotherapy.

scholarly journals Glucose restriction drives spatial re-organization of mevalonate metabolism and liquid-crystalline lipid droplet biogenesis

2020 ◽  
Author(s):  
Sean Rogers ◽  
Hanaa Hariri ◽  
Long Gui ◽  
N. Ezgi Wood ◽  
Natalie Speer ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Mevalonate Pathway ◽  
Dependent Manner ◽  
Metabolic Remodeling ◽  
Ester Biosynthesis ◽  
Metabolic Reactions ◽  
Glucose Restriction ◽  
Rate Limiting ◽  
Pathway Flux

AbstractEukaryotes compartmentalize metabolic pathways into sub-cellular domains, but the role of inter-organelle contacts in organizing metabolic reactions remains poorly understood. Here, we show that in response to acute glucose restriction (AGR) yeast undergo metabolic remodeling of their mevalonate pathway that is spatially coordinated at nucleus-vacuole junctions (NVJs). The NVJ serves as a metabolic platform by selectively retaining HMG-CoA Reductases (HMGCRs), driving mevalonate pathway flux in an Upc2-dependent manner. AGR-induced HMGCR compartmentalization enhances mevalonate metabolism and sterol-ester biosynthesis that generates lipid droplets (LDs) with liquid-crystalline sub-architecture. Loss of NVJ-dependent HMGCR partitioning affects yeast growth, but can be bypassed by artificially multimerizing HMGCRs, indicating NVJ compartmentalization enhances mevalonate pathway flux by promoting HMGCR inter-enzyme associations. We propose a non-canonical mechanism regulating mevalonate metabolism via the spatial compartmentalization of rate-limiting HMGCR enzymes, and reveal that AGR creates LDs with remarkable phase transition properties.One Sentence SummarySpatial compartmentalization of HMG-CoA Reductases at ER-lysosome contacts modulates mevalonate pathway flux

scholarly journals Regulated degradation of HMG-CoA reductase, an integral membrane protein of the endoplasmic reticulum, in yeast.

1994 ◽  
Vol 125 (2) ◽  
pp. 299-312 ◽  
Author(s):  
R Y Hampton ◽  
J Rine
Keyword(s):  
Mevalonate Pathway ◽  
Integral Membrane Protein ◽  
Integral Membrane Proteins ◽  
Hmg Coa Reductase ◽  
Key Enzyme ◽  
Farnesylated Protein ◽  
The Stability ◽  
Coa Reductase ◽  
Pathway Flux

Numerous integral membrane proteins are degraded in the mammalian ER. HMG-CoA reductase (HMG-R), a key enzyme in the mevalonate pathway by which isoprenoids and sterols are synthesized, is one substrate of ER degradation. The degradation of HMG-R is modulated by feedback signals from the mevalonate pathway. We investigated the role of regulated degradation of the two isozymes of HMG-R, Hmg1p and Hmg2p, in the physiology of Saccharomyces cerevisiae. Hmg1p was quite stable, whereas Hmg2p was rapidly degraded. Degradation of Hmg2p proceeded independently of vacuolar proteases or secretory traffic, indicating that Hmg2p degradation occurred at the ER. Hmg2p stability was strongly affected by modulation of the mevalonate pathway through pharmacological or genetic means. Decreased mevalonate pathway flux resulted in decreased degradation of Hmg2p. One signal for degradation of Hmg2p was a nonsterol, mevalonate-derived molecule produced before the synthesis of squalene. Genetic evidence indicated that a farnesylated protein may also be necessary for Hmg2p degradation. Studies with reporter genes demonstrated that the stability of each isozyme was determined by its noncatalytic NH2-terminal domain. Our data show that ER protein degradation is widely conserved among eukaryotes, and that feedback control of HMG-R degradation is an ancient paradigm of regulation.

scholarly journals Enhanced ER-associated degradation of HMG CoA reductase causes embryonic lethality associated with Ubiad1 deficiency

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Youngah Jo ◽  
Steven S Kim ◽  
Kristina Garland ◽  
Iris Fuentes ◽  
Lisa M DiCarlo ◽  
...  
Keyword(s):  
Cultured Cells ◽  
Germ Line ◽  
Mevalonate Pathway ◽  
Gene Knockout ◽  
Homozygous Deletion ◽  
Embryonic Lethality ◽  
Hmg Coa Reductase ◽  
Future Studies ◽  
Coa Reductase ◽  
Rate Limiting

UbiA prenyltransferase domain-containing protein-1 (UBIAD1) synthesizes the vitamin K subtype menaquinone-4 (MK-4). Previous studies in cultured cells (Schumacher et al., 2015) revealed that UBIAD1 also inhibits endoplasmic reticulum (ER)-associated degradation (ERAD) of ubiquitinated HMG CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway that produces cholesterol and essential nonsterol isoprenoids. Gene knockout studies were previously attempted to explore the function of UBIAD1 in mice; however, homozygous germ-line elimination of the Ubiad1 gene caused embryonic lethality. We now report that homozygous deletion of Ubiad1 is produced in knockin mice expressing ubiquitination/ERAD-resistant HMGCR. Thus, embryonic lethality of Ubiad1 deficiency results from depletion of mevalonate-derived products owing to enhanced ERAD of HMGCR rather than from reduced synthesis of MK-4. These findings provide genetic evidence for the significance of UBIAD1 in regulation of cholesterol synthesis and offer the opportunity in future studies for the discovery of new physiological roles of MK-4.

scholarly journals Role of 26S proteasome and HRD genes in the degradation of 3-hydroxy-3-methylglutaryl-CoA reductase, an integral endoplasmic reticulum membrane protein.

1996 ◽  
Vol 7 (12) ◽  
pp. 2029-2044 ◽  
Author(s):  
R Y Hampton ◽  
R G Gardner ◽  
J Rine
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Mevalonate Pathway ◽  
26S Proteasome ◽  
Negative Regulator ◽  
Sterol Synthesis ◽  
Endoplasmic Reticulum Membrane ◽  
Coding Region ◽  
Coa Reductase

3-hydroxy-3-methylglutaryl-CoA reductase (HMG-R), a key enzyme of sterol synthesis, is an integral membrane protein of the endoplasmic reticulum (ER). In both humans and yeast, HMG-R is degraded at or in the ER. The degradation of HMG-R is regulated as part of feedback control of the mevalonate pathway. Neither the mechanism of degradation nor the nature of the signals that couple the degradation of HMG-R to the mevalonate pathway is known. We have launched a genetic analysis of the degradation of HMG-R in Saccharomyces cerevisiae using a selection for mutants that are deficient in the degradation of Hmg2p, an HMG-R isozyme. The underlying genes are called HRD (pronounced "herd"), for HMG-CoA reductase degradation. So far we have discovered mutants in three genes: HRD1, HRD2, and HRD3. The sequence of the HRD2 gene is homologous to the p97 activator of the 26S proteasome. This p97 protein, also called TRAP-2, has been proposed to be a component of the mature 26S proteasome. The hrd2-1 mutant had numerous pleiotropic phenotypes expected for cells with a compromised proteasome, and these phenotypes were complemented by the human TRAP-2/p97 coding region. In contrast, HRD1 and HRD3 genes encoded previously unknown proteins predicted to be membrane bound. The Hrd3p protein was homologous to the Caenorhabditis elegans sel-1 protein, a negative regulator of at least two different membrane proteins, and contained an HRD3 motif shared with several other proteins. Hrd1p had no full-length homologues, but contained an H2 ring finger motif. These data suggested a model of ER protein degradation in which the Hrd1p and Hrd3p proteins conspire to deliver HMG-R to the 26S proteasome. Moreover, our results lend in vivo support to the proposed role of the p97/TRAP-2/Hrd2p protein as a functionally important component of the 26S proteasome. Because the HRD genes were required for the degradation of both regulated and unregulated substrates of ER degradation, the HRD genes are the agents of HMG-R degradation but not the regulators of that degradation.

scholarly journals 083 Is HMGR the Key Regulator of α-Farnesene Biosynthesis of Apple?

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 403A-403
Author(s):  
H.P.V. Rupasinghe ◽  
K.C. Almquist ◽  
G. Paliyath ◽  
D.P. Murr
Keyword(s):  
Mevalonate Pathway ◽  
Higher Plants ◽  
Competitive Inhibitor ◽  
The Novel ◽  
Rate Limiting Step ◽  
Ethylene Action ◽  
Hmgr Activity ◽  
Coa Reductase ◽  
Rate Limiting

We tested the hypothesis that conversion of 3-hydroxy-3-methylglutaryl co-enzyme A (HMG CoA) to mevalonate (MVA) catalyzed by HMG CoA reductase (HMGR) is the rate limiting step for α-farnesene biosynthesis of apples. In higher plants, isopentenyl pyrophosphate (IPP) is derived via two pathways: 1) the classical mevalonate pathway, and 2) the novel glyceraldehyde-3-phosphate (GAP)/pyruvate pathway independent of HMGR action. When apple skin discs were incubated with MVA, or GAP and pyruvate, MVA increased α-farnesene levels in the skin but not GAP and pyruvate. Treating apple fruits with Lovastatin (1000 ppm), a competitive inhibitor of HMGR, inhibited α-farnesene accumulation in the skin by 20% to 50% during storage. Content of α-farnesene in the skin increased during the first 2 to 4 months in storage, and then decreased. In contrast, HMGR activity, as determined by the conversion of [4-3H]HMG CoA to MVA in the total membrane and soluble fraction, was the highest at the time of harvest and gradually decreased during 5 months of storage in air at 0 °C. The potent ethylene action inhibitor 1-MCP inhibited ethylene production and α-farnesene evolution by 99% and 97%, respectively. The effect of 1-MCP on in vitro activity of HMGR was marginal (≈30% inhibition). 1-MCP inhibited respiratory CO2 evolution by 50%, which suggests also that inhibition by 1-MCP of α-farnesene synthesis in apple could be regulated by the acetyl CoA pool. In plants, HMGR is encoded by a small gene family and differentially expressed. As the first step of studying the molecular mechanism of HMGR regulation, we have isolated a 444-bp fragment of apple hmgr gene using apple skin mRNA and degenerate oligonucleotides designed against conserved regions of plant hmgr genes.

scholarly journals Glucose restriction drives spatial reorganization of mevalonate metabolism

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sean M Rogers ◽  
Hanaa Hariri ◽  
N Ezgi M Wood ◽  
Natalie Ortiz Speer ◽  
W Mike Henne
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Mevalonate Pathway ◽  
Dependent Manner ◽  
Metabolic Remodeling ◽  
Spatial Reorganization ◽  
Glucose Restriction ◽  
Rate Limiting ◽  
Pathway Flux

Eukaryotes compartmentalize metabolic pathways into sub-cellular domains, but the role of inter-organelle contacts in organizing metabolic reactions remains poorly understood. Here, we show that in response to acute glucose restriction (AGR) yeast undergo metabolic remodeling of their mevalonate pathway that is spatially coordinated at nucleus-vacuole junctions (NVJs). The NVJ serves as a metabolic platform by selectively retaining HMG-CoA Reductases (HMGCRs), driving mevalonate pathway flux in an Upc2-dependent manner. Both spatial retention of HMGCRs and increased mevalonate pathway flux during AGR is dependent on NVJ tether Nvj1. Furthermore, we demonstrate that HMGCRs associate into high molecular weight assemblies during AGR in an Nvj1-dependent manner. Loss of Nvj1-mediated HMGCR partitioning can be bypassed by artificially multimerizing HMGCRs, indicating NVJ compartmentalization enhances mevalonate pathway flux by promoting the association of HMGCRs in high molecular weight assemblies. Loss of HMGCR compartmentalization perturbs yeast growth following glucose starvation, indicating it promotes adaptive metabolic remodeling. Collectively we propose a non-canonical mechanism regulating mevalonate metabolism via the spatial compartmentalization of rate-limiting HMGCR enzymes at an inter-organelle contact site.

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