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1.
Elife ; 132024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38602170

RESUMO

Stains are known to be anti-inflammatory, but the mechanism remains poorly understood. Here we show that macrophages, either treated with statin in vitro or from statin-treated mice, have reduced cholesterol levels and higher expression of Jmjd3, a H3K27me3 demethylase. We provide evidence that lowering cholesterol levels in macrophages suppresses the ATP synthase in the inner mitochondrial membrane (IMM) and changes the proton gradient in the mitochondria. This activates NFkB and Jmjd3 expression to remove the repressive marker H3K27me3. Accordingly, the epigenome is altered by the cholesterol reduction. When subsequently challenged by the inflammatory stimulus LPS (M1), both macrophages treated with statins in vitro or isolated from statin-treated mice in vivo, express lower levels pro-inflammatory cytokines than controls, while augmenting anti-inflammatory Il10 expression. On the other hand, when macrophages are alternatively activated by IL4 (M2), statins promote the expression of Arg1, Ym1, and Mrc1. The enhanced expression is correlated with the statin-induced removal of H3K27me3 from these genes prior to activation. In addition, Jmjd3 and its demethylase activity are necessary for cholesterol to modulate both M1 and M2 activation. We conclude that upregulation of Jmjd3 is a key event for the anti-inflammatory function of statins on macrophages.

2.
J Cell Biol ; 223(4)2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38429999

RESUMO

Cholesterol from low-density lipoprotein (LDL) can be transported to many organelle membranes by non-vesicular mechanisms involving sterol transfer proteins (STPs). Fatty acid-binding protein (FABP) 7 was identified in our previous study searching for new regulators of intracellular cholesterol trafficking. Whether FABP7 is a bona fide STP remains unknown. Here, we found that FABP7 deficiency resulted in the accumulation of LDL-derived cholesterol in lysosomes and reduced cholesterol levels on the plasma membrane. A crystal structure of human FABP7 protein in complex with cholesterol was resolved at 2.7 Å resolution. In vitro, FABP7 efficiently transported the cholesterol analog dehydroergosterol between the liposomes. Further, the silencing of FABP3 and 8, which belong to the same family as FABP7, caused robust cholesterol accumulation in lysosomes. These two FABP proteins could transport dehydroergosterol in vitro as well. Collectively, our results suggest that FABP3, 7, and 8 are a new class of STPs mediating cholesterol egress from lysosomes.


Assuntos
Colesterol , Proteínas de Ligação a Ácido Graxo , Lisossomos , Humanos , Membrana Celular/metabolismo , Colesterol/metabolismo , Proteínas de Ligação a Ácido Graxo/genética , Proteínas de Ligação a Ácido Graxo/metabolismo , Lisossomos/metabolismo , Esteróis/metabolismo
3.
Cell Chem Biol ; 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38442710

RESUMO

The hedgehog (Hh) signaling pathway has long been a hotspot for anti-cancer drug development due to its important role in cell proliferation and tumorigenesis. However, most clinically available Hh pathway inhibitors target the seven-transmembrane region (7TM) of smoothened (SMO), and the acquired drug resistance is an urgent problem in SMO inhibitory therapy. Here, we identify a sterol analog Q29 and show that it can inhibit the Hh pathway through binding to the cysteine-rich domain (CRD) of SMO and blocking its cholesterylation. Q29 suppresses Hh signaling-dependent cell proliferation and arrests Hh-dependent medulloblastoma growth. Q29 exhibits an additive inhibitory effect on medulloblastoma with vismodegib, a clinically used SMO-7TM inhibitor for treating basal cell carcinoma (BCC). Importantly, Q29 overcomes resistance caused by SMO mutants against SMO-7TM inhibitors and inhibits the activity of SMO oncogenic variants. Our work demonstrates that the SMO-CRD inhibitor can be a new way to treat Hh pathway-driven cancers.

4.
EMBO Mol Med ; 16(2): 334-360, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38177537

RESUMO

Cancer immunotherapies have achieved unprecedented success in clinic, but they remain largely ineffective in some major types of cancer, such as colorectal cancer with microsatellite stability (MSS CRC). It is therefore important to study tumor microenvironment of resistant cancers for developing new intervention strategies. In this study, we identify a metabolic cue that determines the unique immune landscape of MSS CRC. Through secretion of distal cholesterol precursors, which directly activate RORγt, MSS CRC cells can polarize T cells toward Th17 cells that have well-characterized pro-tumor functions in colorectal cancer. Analysis of large human cancer cohorts revealed an asynchronous pattern of the cholesterol biosynthesis in MSS CRC, which is responsible for the abnormal accumulation of distal cholesterol precursors. Inhibiting the cholesterol biosynthesis enzyme Cyp51, by pharmacological or genetic interventions, reduced the levels of intratumoral distal cholesterol precursors and suppressed tumor progression through a Th17-modulation mechanism in preclinical MSS CRC models. Our study therefore reveals a novel mechanism of cancer-immune interaction and an intervention strategy for the difficult-to-treat MSS CRC.


Assuntos
Neoplasias Colorretais , Instabilidade de Microssatélites , Humanos , Neoplasias Colorretais/genética , Microambiente Tumoral
5.
bioRxiv ; 2024 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-36711703

RESUMO

Stains are known to be anti-inflammatory, but the mechanism remains poorly understood. Here we show that macrophages, either treated with statin in vitro or from statin-treated mice, have reduced cholesterol levels and higher expression of Jmjd3, a H3K27me3 demethylase. We provide evidence that lowering cholesterol levels in macrophages suppresses the ATP synthase in the inner mitochondrial membrane (IMM) and changes the proton gradient in the mitochondria. This activates NFkB and Jmjd3 expression to remove the repressive marker H3K27me3. Accordingly, the epigenome is altered by the cholesterol reduction. When subsequently challenged by the inflammatory stimulus LPS (M1), both macrophages treated with statins in vitro or isolated from statin-treated mice in vivo, express lower levels pro-inflammatory cytokines than controls, while augmenting anti-inflammatory Il10 expression. On the other hand, when macrophages are alternatively activated by IL4 (M2), statins promote the expression of Arg1, Ym1, and Mrc1. The enhanced expression is correlated with the statin-induced removal of H3K27me3 from these genes prior to activation. In addition, Jmjd3 and its demethylase activity are necessary for cholesterol to modulate both M1 and M2 activation. We conclude that upregulation of Jmjd3 is a key event for the anti-inflammatory function of statins on macrophages.

6.
Sci Adv ; 9(48): eadj4605, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-38019907

RESUMO

Protein degradation in eukaryotic cells is mainly carried out by the 26S proteasome, a macromolecular complex not only present in the cytosol and nucleus but also associated with various membranes. How proteasomes are anchored to the membrane and the biological meaning thereof have been largely unknown in higher organisms. Here, we show that N-myristoylation of the Rpt2 subunit is a general mechanism for proteasome-membrane interaction. Loss of this modification in the Rpt2-G2A mutant cells leads to profound changes in the membrane-associated proteome, perturbs the endomembrane system, and undermines critical cellular processes such as cell adhesion, endoplasmic reticulum-associated degradation and membrane protein trafficking. Rpt2G2A/G2A homozygous mutation is embryonic lethal in mice and is sufficient to abolish tumor growth in a nude mice xenograft model. These findings have defined an evolutionarily conserved mechanism for maintaining membrane protein homeostasis and underscored the significance of compartmentalized protein degradation by myristoyl-anchored proteasomes in health and disease.


Assuntos
Proteínas de Membrana , Complexo de Endopeptidases do Proteassoma , Humanos , Animais , Camundongos , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteostase , Degradação Associada com o Retículo Endoplasmático , Camundongos Nus , Lipídeos
7.
J Lipid Res ; 64(12): 100465, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37890669

RESUMO

Accurate intracellular cholesterol traffic plays crucial roles. Niemann Pick type C (NPC) proteins NPC1 and NPC2, are two lysosomal cholesterol transporters that mediate the cholesterol exit from lysosomes. However, other proteins involved in this process remain poorly defined. Here, we find that the previously unannotated protein TMEM241 is required for cholesterol egressing from lysosomes through amphotericin B-based genome-wide CRISPR-Cas9 KO screening. Ablation of TMEM241 caused impaired sorting of NPC2, a protein utilizes the mannose-6-phosphate (M6P) modification for lysosomal targeting, resulting in cholesterol accumulation in the lysosomes. TMEM241 is a member of solute transporters 35 nucleotide sugar transporters family and localizes on the cis-Golgi network. Our data indicate that TMEM241 transports UDP-N-acetylglucosamine (UDP-GlcNAc) into Golgi lumen and UDP-GlcNAc is used for the M6P modification of proteins including NPC2. Furthermore, Tmem241-deficient mice display cholesterol accumulation in pulmonary cells and behave pulmonary injury and hypokinesia. Taken together, we demonstrate that TMEM241 is a Golgi-localized UDP-GlcNAc transporter and loss of TMEM241 causes cholesterol accumulation in lysosomes because of the impaired M6P-dependent lysosomal targeting of NPC2.


Assuntos
Colesterol , Proteínas de Transporte Vesicular , Animais , Camundongos , Proteínas de Transporte Vesicular/metabolismo , Colesterol/metabolismo , Difosfato de Uridina/metabolismo , Lisossomos/metabolismo
8.
Nat Commun ; 14(1): 6469, 2023 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-37833289

RESUMO

Niemann-Pick C1-like 1 (NPC1L1) is essential for intestinal cholesterol absorption. Together with the cholesterol-rich and Flotillin-positive membrane microdomain, NPC1L1 is internalized via clathrin-mediated endocytosis and transported to endocytic recycling compartment (ERC). When ERC cholesterol level decreases, NPC1L1 interacts with LIMA1 and moves back to plasma membrane. However, how cholesterol leaves ERC is unknown. Here, we find that, in male mice, intracellular bile acids facilitate cholesterol transport to other organelles, such as endoplasmic reticulum, in a non-micellar fashion. When cholesterol level in ERC is decreased by bile acids, the NPC1L1 carboxyl terminus that previously interacts with the cholesterol-rich membranes via the A1272LAL residues dissociates from membrane, exposing the Q1277KR motif for LIMA1 recruitment. Then NPC1L1 moves back to plasma membrane. This study demonstrates an intracellular cholesterol transport function of bile acids and explains how the substantial amount of cholesterol in NPC1L1-positive compartments is unloaded in enterocytes during cholesterol absorption.


Assuntos
Colesterol , Proteínas de Membrana Transportadoras , Animais , Masculino , Camundongos , Transporte Biológico , Membrana Celular/metabolismo , Colesterol/metabolismo , Absorção Intestinal , Proteínas de Membrana Transportadoras/metabolismo
9.
Nat Cell Biol ; 25(7): 937-949, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37277481

RESUMO

The low-density lipoprotein (LDL) is a major cholesterol carrier in circulation and is internalized into cells through LDL receptor (LDLR)-mediated endocytosis. The LDLR protein is highly expressed in the steroidogenic organs and LDL cholesterol is an important source for steroidogenesis. Cholesterol must be transported into the mitochondria, where steroid hormone biosynthesis initiates. However, how LDL cholesterol is conveyed to the mitochondria is poorly defined. Here, through genome-wide small hairpin RNA screening, we find that the outer mitochondrial membrane protein phospholipase D6 (PLD6), which hydrolyses cardiolipin to phosphatidic acid, accelerates LDLR degradation. PLD6 promotes the entrance of LDL and LDLR into the mitochondria, where LDLR is degraded by mitochondrial proteases and LDL-carried cholesterol is used for steroid hormone biosynthesis. Mechanistically, the outer mitochondrial membrane protein CISD2 binds to the cytosolic tail of LDLR and tethers LDLR+ vesicles to the mitochondria. The fusogenic lipid phosphatidic acid generated by PLD6 facilitates the membrane fusion of LDLR+ vesicles with the mitochondria. This intracellular transport pathway of LDL-LDLR bypasses the lysosomes and delivers cholesterol to the mitochondria for steroidogenesis.


Assuntos
Colesterol , Mitocôndrias , LDL-Colesterol , Colesterol/metabolismo , Mitocôndrias/metabolismo , Proteínas de Membrana/metabolismo , Hormônios
10.
Arterioscler Thromb Vasc Biol ; 43(7): 1219-1233, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37165876

RESUMO

BACKGROUND: Lower plasma levels of LDL (low-density lipoprotein) cholesterol (LDL-C) can reduce the risk of atherosclerotic cardiovascular disease. The loss-of-function mutations in PCSK9 (proprotein convertase subtilisin/kexin type 9) have been known to associate with low LDL-C in many human populations. PCSK9 genetic variants in Chinese Uyghurs who are at high risk of atherosclerotic cardiovascular disease due to their dietary habits have not been reported. METHODS: The study involved the whole-exome and target sequencing of college students from Uyghur and other ethnic groups in Xinjiang, China, for the association of PCSK9 loss-of-function mutations with low plasma levels of LDL-C. The mechanisms by which the identified mutations affect the function of PCSK9 were investigated in cultured cells using biochemical and cell assays. The causal effects of the identified PCSK9 mutations on LDL-C levels were verified in mice injected with adeno-associated virus expressing different forms of PCSK9 and fed a high-cholesterol diet. RESULTS: We identified 2 PCSK9 mutations-E144K and C378W-in Chinese Uyghurs with low plasma levels of LDL-C. The E144K and C378W mutations impaired the maturation and secretion of the PCSK9 protein, respectively. Adeno-associated virus-mediated expression of E144K and C378W mutants in Pcsk9 KO (knockout) mice fed a high-cholesterol diet also hampered PCSK9 secretion into the serum, resulting in elevated levels of LDL receptor in the liver and reduced levels of LDL-C in the serum. CONCLUSIONS: Our study shows that E144K and C378W are PCSK9 loss-of-function mutations causing low LDL-C levels in mice and probably in humans as well.


Assuntos
Aterosclerose , Doenças Cardiovasculares , Hipercolesterolemia , Humanos , Camundongos , Animais , Pró-Proteína Convertase 9/genética , LDL-Colesterol , Serina Endopeptidases/genética , Pró-Proteína Convertases/genética , Pró-Proteína Convertases/metabolismo , Receptores de LDL/genética , Receptores de LDL/metabolismo , Camundongos Knockout , Aterosclerose/genética , Aterosclerose/prevenção & controle , Aterosclerose/metabolismo , Mutação
11.
bioRxiv ; 2023 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-37214852

RESUMO

Protein degradation in eukaryotic cells is mainly carried out by the 26S proteasome, a macromolecular complex not only present in the cytosol and nucleus but also associated with various membranes. How proteasomes are anchored to the membrane and the biological meaning thereof have been largely unknown in higher organisms. Here we show that N-myristoylation of the Rpt2 subunit is a general mechanism for proteasome-membrane interaction. Loss of this modification in the Rpt2-G2A mutant cells leads to profound changes in the membrane-associated proteome, perturbs the endomembrane system and undermines critical cellular processes such as cell adhesion, endoplasmic reticulum-associated degradation (ERAD) and membrane protein trafficking. Rpt2 G2A/G2A homozygous mutation is embryonic lethal in mice and is sufficient to abolish tumor growth in a nude mice xenograft model. These findings have defined an evolutionarily conserved mechanism for maintaining membrane protein homeostasis and underscored the significance of compartmentalized protein degradation by m yristoyl- a nchored p roteasomes (MAPs) in health and disease.

12.
Cancer Cell ; 41(7): 1276-1293.e11, 2023 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-37244259

RESUMO

The concept of targeting cholesterol metabolism to treat cancer has been widely tested in clinics, but the benefits are modest, calling for a complete understanding of cholesterol metabolism in intratumoral cells. We analyze the cholesterol atlas in the tumor microenvironment and find that intratumoral T cells have cholesterol deficiency, while immunosuppressive myeloid cells and tumor cells display cholesterol abundance. Low cholesterol levels inhibit T cell proliferation and cause autophagy-mediated apoptosis, particularly for cytotoxic T cells. In the tumor microenvironment, oxysterols mediate reciprocal alterations in the LXR and SREBP2 pathways to cause cholesterol deficiency of T cells, subsequently leading to aberrant metabolic and signaling pathways that drive T cell exhaustion/dysfunction. LXRß depletion in chimeric antigen receptor T (CAR-T) cells leads to improved antitumor function against solid tumors. Since T cell cholesterol metabolism and oxysterols are generally linked to other diseases, the new mechanism and cholesterol-normalization strategy might have potential applications elsewhere.


Assuntos
Antineoplásicos , Neoplasias , Oxisteróis , Humanos , Colesterol/metabolismo , Ativação Linfocitária , Imunoterapia Adotiva , Microambiente Tumoral
14.
Sci China Life Sci ; 66(8): 1786-1799, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-36971991

RESUMO

Peroxisomal disorders (PDs) are a heterogenous group of diseases caused by defects in peroxisome biogenesis or functions. X-linked adrenoleukodystrophy is the most prevalent form of PDs and results from mutations in the ABCD1 gene, which encodes a transporter mediating the uptake of very long-chain fatty acids (VLCFAs). The curative approaches for PDs are very limited. Here, we investigated whether cholesterol accumulation in the lysosomes is a biochemical feature shared by a broad spectrum of PDs. We individually knocked down fifteen PD-associated genes in cultured cells and found ten induced cholesterol accumulation in the lysosome. 2-Hydroxypropyl-ß-cyclodextrin (HPCD) effectively alleviated the cholesterol accumulation phenotype in PD-mimicking cells through reducing intracellular cholesterol content as well as promoting cholesterol redistribution to other cellular membranes. In ABCD1 knockdown cells, HPCD treatment lowered reactive oxygen species and VLCFA to normal levels. In Abcd1 knockout mice, HPCD injections reduced cholesterol and VLCFA sequestration in the brain and adrenal cortex. The plasma levels of adrenocortical hormones were increased and the behavioral abnormalities were greatly ameliorated upon HPCD administration. Together, our results suggest that defective cholesterol transport underlies most, if not all, PDs, and that HPCD can serve as a novel and effective strategy for the treatment of PDs.


Assuntos
Transportadores de Cassetes de Ligação de ATP , Adrenoleucodistrofia , Camundongos , Animais , Transportadores de Cassetes de Ligação de ATP/genética , 2-Hidroxipropil-beta-Ciclodextrina/farmacologia , Ácidos Graxos/química , Adrenoleucodistrofia/genética , Colesterol , Lisossomos , Membro 1 da Subfamília D de Transportadores de Cassetes de Ligação de ATP/genética
15.
J Biol Chem ; 299(4): 103073, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36858198

RESUMO

Polycomb repressive complex 2 (PRC2) suppresses gene transcription by methylating lysine 27 of histone H3 (H3K27) and plays critical roles in embryonic development. Among the core PRC2 subunits, EZH2 is the catalytic subunit and EED allosterically activates EZH2 upon binding trimethylated H3K27 (H3K27me3). Activating mutations on Y641, A677, and A687 within the enzymatic SET (Su(Var)3 to 9, Enhancer-of-zeste, and Trithorax) domain of EZH2 have been associated with enhanced H3K27me3 and tumorigenicity of many cancers including B-cell lymphoma and melanoma. To tackle the critical residues outside the EZH2 SET domain, we examined EZH2 mutations in lymphoma from cancer genome databases and identified a novel gain-of-function mutation W113C, which increases H3K27me3 in vitro and in vivo and promotes CDKN2A silencing to a similar level as EZH2 Y641F. Different from other gain-of-function mutations, this mutation is located in the SET-activation loop at the EZH2 N terminus, which stabilizes the SET domain and facilitates substrate binding. This may explain how the W113C mutation increases PRC2 activity. Tazemetostat is a Food and Drug Administration-approved EZH2-binding inhibitor for follicular lymphoma treatment. Intriguingly, the W113C mutation leads to tazemetostat resistance in both H3K27 methylation and tumor proliferation. Another class of allosteric PRC2 inhibitor binding EED overcomes the resistance, effectively decreases H3K27me3, and blocks tumor proliferation in cells expressing EZH2 W113C. As this mutation is originally identified from lymphoma samples, our results demonstrated its activating characteristic and the deleterious consequence, provide insights on PRC2 regulation, and support the continued exploration of treatment optimization for lymphoma patients.


Assuntos
Resistencia a Medicamentos Antineoplásicos , Mutação com Ganho de Função , Linfoma de Células B , Humanos , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Histonas/metabolismo , Linfoma de Células B/tratamento farmacológico , Linfoma de Células B/genética , Mutação , Complexo Repressor Polycomb 2/genética
16.
EMBO J ; 42(3): e111513, 2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36524353

RESUMO

Hedgehog (Hh) signaling pathway plays a pivotal role in embryonic development. Hh binding to Patched1 (PTCH1) derepresses Smoothened (SMO), thereby activating the downstream signal transduction. Covalent SMO modification by cholesterol in its cysteine-rich domain (CRD) is essential for SMO function. SMO cholesterylation is a calcium-accelerated autoprocessing reaction, and STIM1-ORAI1-mediated store-operated calcium entry promotes cholesterylation and activation of endosome-localized SMO. However, it is unknown whether the Hh-PTCH1 interplay regulates the activity of the endoplasmic reticulum (ER)-localized SMO. Here, we found that PTCH1 inhibited the COPII-dependent export of SMO from the ER, whereas Hh promoted this process. The RRxWxR amino acid motif in the cytosolic tail of SMO was essential for COPII recognition, ciliary localization, and signal transduction activity. Hh and PTCH1 regulated cholesterol modification of the ER-localized SMO, and SMO cholesterylation accelerated its exit from ER. The GRAMD1/ASTER sterol transport proteins facilitated cholesterol transfer to ER from PM, resulting in increased SMO cholesterylation and enhanced Hh signaling. Collectively, we reveal a regulatory role of GRAMD-mediated cholesterol transport in ER-resident SMO maturation and Hh signaling.


Assuntos
Cálcio , Proteínas Hedgehog , Transporte Biológico , Cálcio/metabolismo , Colesterol/metabolismo , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/fisiologia , Receptor Smoothened/genética , Receptor Smoothened/metabolismo , Proteínas de Membrana/metabolismo
17.
Nat Metab ; 4(9): 1166-1184, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36123394

RESUMO

Adipose tissue undergoes thermogenic remodeling in response to thermal stress and metabolic cues, playing a crucial role in regulating energy expenditure and metabolic homeostasis. Endoplasmic reticulum (ER) stress is associated with adipose dysfunction in obesity and metabolic disease. It remains unclear, however, if ER stress-signaling in adipocytes mechanistically mediates dysregulation of thermogenic fat. Here we show that inositol-requiring enzyme 1α (IRE1α), a key ER stress sensor and signal transducer, acts in both white and beige adipocytes to impede beige fat activation. Ablation of adipocyte IRE1α promotes browning/beiging of subcutaneous white adipose tissue following cold exposure or ß3-adrenergic stimulation. Loss of IRE1α alleviates diet-induced obesity and augments the anti-obesity effect of pharmacologic ß3-adrenergic stimulation. Notably, IRE1α suppresses stimulated lipolysis and degrades Ppargc1a messenger RNA through its RNase activity to downregulate the thermogenic gene program. Hence, blocking IRE1α bears therapeutic potential in unlocking adipocytes' thermogenic capacity to combat obesity and metabolic disorders.


Assuntos
Endorribonucleases , Inositol , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proteínas Serina-Treonina Quinases , Adipócitos/metabolismo , Adrenérgicos/farmacologia , Animais , Endorribonucleases/genética , Endorribonucleases/metabolismo , Inositol/farmacologia , Camundongos , Obesidade/genética , Obesidade/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Estabilidade de RNA , RNA Mensageiro , Termogênese/genética
18.
Nature ; 608(7922): 413-420, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35922515

RESUMO

High cholesterol is a major risk factor for cardiovascular disease1. Currently, no drug lowers cholesterol through directly promoting cholesterol excretion. Human genetic studies have identified that the loss-of-function Asialoglycoprotein receptor 1 (ASGR1) variants associate with low cholesterol and a reduced risk of cardiovascular disease2. ASGR1 is exclusively expressed in liver and mediates internalization and lysosomal degradation of blood asialoglycoproteins3. The mechanism by which ASGR1 affects cholesterol metabolism is unknown. Here, we find that Asgr1 deficiency decreases lipid levels in serum and liver by stabilizing LXRα. LXRα upregulates ABCA1 and ABCG5/G8, which promotes cholesterol transport to high-density lipoprotein and excretion to bile and faeces4, respectively. ASGR1 deficiency blocks endocytosis and lysosomal degradation of glycoproteins, reduces amino-acid levels in lysosomes, and thereby inhibits mTORC1 and activates AMPK. On one hand, AMPK increases LXRα by decreasing its ubiquitin ligases BRCA1/BARD1. On the other hand, AMPK suppresses SREBP1 that controls lipogenesis. Anti-ASGR1 neutralizing antibody lowers lipid levels by increasing cholesterol excretion, and shows synergistic beneficial effects with atorvastatin or ezetimibe, two widely used hypocholesterolaemic drugs. In summary, this study demonstrates that targeting ASGR1 upregulates LXRα, ABCA1 and ABCG5/G8, inhibits SREBP1 and lipogenesis, and therefore promotes cholesterol excretion and decreases lipid levels.


Assuntos
Receptor de Asialoglicoproteína , Colesterol , Metabolismo dos Lipídeos , Proteínas Quinases Ativadas por AMP/metabolismo , Transportador 1 de Cassete de Ligação de ATP , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Membro 8 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Receptor de Asialoglicoproteína/antagonistas & inibidores , Receptor de Asialoglicoproteína/deficiência , Receptor de Asialoglicoproteína/genética , Receptor de Asialoglicoproteína/metabolismo , Assialoglicoproteínas/metabolismo , Atorvastatina/farmacologia , Proteína BRCA1 , Doenças Cardiovasculares/genética , Doenças Cardiovasculares/metabolismo , Colesterol/metabolismo , Sinergismo Farmacológico , Endocitose , Ezetimiba/farmacologia , Humanos , Lipídeos/análise , Lipídeos/sangue , Fígado/metabolismo , Receptores X do Fígado/metabolismo , Lisossomos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Proteína de Ligação a Elemento Regulador de Esterol 1 , Ubiquitina-Proteína Ligases/metabolismo
19.
Acta Biochim Biophys Sin (Shanghai) ; 54(8): 1171-1179, 2022 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-35904215

RESUMO

The Hedgehog (Hh) signaling pathway is critical for embryonic development and tissue renewal. The G protein-coupled receptor (GPCR)-like protein Smoothened (SMO) is the central signal transducer in the Hh pathway. Cholesterol binds and then covalently links to the D95 residue of cysteine-rich domain (CRD) of human SMO. The cholesterylation of CRD is critical for SMO activation. SMO cholesterylation is a Ca 2+-boosted autoreaction that requires the formation of an ester bond between the side chains of D95 and Y130 as an intermediate. It is unknown whether other residues of SMO are involved in the esterification between D95 and cholesterol. In this study, we find that the SMO-CRD(27-192) can undergo cholesterylation. In addition to D95 and Y130, the residues critical for cholesterol modification include Y85, T88, T90, W109, W119, K133, E160 and F166. T88, W109, W119 and F166 also seem to be involved in protein folding. Notably, we find that Y85 and K133 form a cation-π interaction whose disruption abolishes cholesterylation and ciliary localization of SMO. This study highlights the mechanism and function of cholesterol modification of SMO.


Assuntos
Cisteína , Proteínas Hedgehog , Cátions , Colesterol/metabolismo , Ésteres , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Humanos , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptor Smoothened/genética , Receptor Smoothened/metabolismo
20.
Eur J Med Chem ; 236: 114323, 2022 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-35397399

RESUMO

HMG-CoA reductase (HMGCR) is the rate-limiting enzyme in cholesterol de novo biosynthesis and its degradation may bring therapeutic benefits for the treatment of cardiovascular disease (CVD) and nonalcoholic steatohepatitis (NASH). Before, we disclosed compound HMG499 as a potent HMGCR degrader, which could be a promising agent for treating CVD, however its side-effect of promoting cholesterol accumulation in cells should be eliminated before progression. Herein, a series of novel heterocyclic ring-fused analogs of HMG499 were synthesized and investigated for their activities of stimulating HMGCR degradation using a HMGCR (TM1-8)-GFP reporting system. Among them, the most active compound 29 (QH536) showed an EC50 of 0.22 µΜ in promoting HMGCR degradation, which was about 2 times more potent than HMG499 (EC50 = 0.43 µM). Interestingly, 29 was different from HMG499, it had no side-effect of inducing cholesterol accumulation in cells. Mechanistic studies disclosed that 29 could significantly decrease statin-induced accumulation of HMGCR protein via ubiquitination and degradation of HMGCR through ubiquitin-proteasome pathway and inhibit the cholesterol biosynthesis in cells. Therefore, these heterocyclic ring-fused analogs could be used as promising leads for the development of new types of agents against CVD. Furthermore, 29 also lowered cholesterol levels and suppressed TGFß1-induced proliferation of LX-2 hepatic stellate cells in a dose-dependent manner. In particular, 29 not only decreased the NASH associated fibrotic mRNA and protein expression of α-SMA, COL1A1, TIMP1 and TGFß1 but also suppressed cholesterol levels and inflammatory genes of TNF-α, IL-6 an IL-1ß in RAW264.7 macrophage cells, indicating that 29 may bring therapeutic benefit to treat NASH.


Assuntos
Doenças Cardiovasculares , Hidroximetilglutaril-CoA Redutases , Hepatopatia Gordurosa não Alcoólica , Colesterol/metabolismo , Humanos , Hidroximetilglutaril-CoA Redutases/genética , Hidroximetilglutaril-CoA Redutases/metabolismo , Ubiquitinação
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