Research Article Details

Article ID: A52005
PMID: 32432943
Source: Autophagy
Title: Discovery of a potent SCAP degrader that ameliorates HFD-induced obesity, hyperlipidemia and insulin resistance via an autophagy-independent lysosomal pathway.
Abstract: SCAP (SREBF chaperone) regulates SREBFs (sterol regulatory element binding transcription factors) processing and stability, and, thus, becomes an emerging drug target to treat dyslipidemia and fatty liver disease. However, the current known SCAP inhibitors, such as oxysterols, induce endoplasmic reticulum (ER) stress and NR1H3/LXRα (nuclear receptor subfamily 1 group H member 3)-SREBF1/SREBP-1 c-mediated hepatic steatosis, which severely limited the clinical application of this inhibitor. In this study, we identified a small molecule, lycorine, which binds to SCAP, which suppressed the SREBF pathway without inducing ER stress or activating NR1H3. Mechanistically, lycorine promotes SCAP lysosomal degradation in a macroautophagy/autophagy-independent pathway, a mechanism completely distinct from current SCAP inhibitors. Furthermore, we determined that SQSTM1 captured SCAP after its exit from the ER. The interaction of SCAP and SQSTM1 requires the WD40 domain of SCAP and the TB domain of SQSTM1. Interestingly, lycorine triggers the lysosome translocation of SCAP independent of autophagy. We termed this novel protein degradation pathway as the SQSTM1-mediated autophagy-independent lysosomal degradation (SMAILD) pathway. In vivo, lycorine ameliorates high-fat diet-induced hyperlipidemia, hepatic steatosis, and insulin resistance in mice. Our study demonstrated that the inhibition of SCAP through the SMAILD pathway could be employed as a useful therapeutic strategy for treating metabolic diseases.Abbreviation: 25-OHD: 25-hydroxyvitamin D; 3-MA: 3-methyladenine; ABCG5: ATP binding cassette subfamily G member 5; ABCG8: ATP binding cassette subfamily G member 8; ACACA: acetyl-CoA carboxylase alpha; AEBSF: 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride; AHI: anhydroicaritin; AKT/protein kinase B: AKT serine/threonine kinase; APOE: apolipoprotein E; ATF6: activating transcription factor 6; ATG: autophagy-related; BAT: brown adipose tissue; CD274/PD-L1: CD274 molecule; CETSA: cellular thermal shift assay; CMA: chaperone-mediated autophagy; COPII: cytoplasmic coat protein complex-II; CQ: chloroquine; DDIT3/CHOP: DNA damage inducible transcript 3; DNL: de novo lipogenesis; EE: energy expenditure; EGFR: epithelial growth factor receptor; eMI: endosomal microautophagy; ERN1/IRE1α: endoplasmic reticulum to nucleus signaling 1; FADS2: fatty acid desaturase 2; FASN: fatty acid synthase; GOT1/AST: glutamic-oxaloacetic transaminase 1; GPT/ALT: glutamic-pyruvate transaminase; HMGCR: 3-hydroxy-3-methylglutaryl-CoA reductase; HMGCS1: 3-hydroxy-3-methylglutaryl-CoA synthase 1; HSP90B1/GRP94: heat shock protein 90 beta family member 1; HSPA5/GRP78: heat hock protein family A (Hsp70) member 5; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; INSIG1: insulin induced gene 1; LAMP2A: lysosomal associated membrane protein 2A; LDLR: low density lipoprotein receptor; LyTACs: lysosome targeting chimeras; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MBTPS1: membrane bound transcription factor peptidase, site 1; MEF: mouse embryonic fibroblast; MST: microscale thermophoresis; MTOR: mechanistic target of rapamycin kinase; MVK: mevalonate kinase; PROTAC: proteolysis targeting chimera; RQ: respiratory quotient; SCAP: SREBF chaperone; SCD1: stearoyl-coenzemy A desaturase 1; SMAILD: sequestosome 1 mediated autophagy-independent lysosomal degradation; SQSTM1: sequestosome 1; SREBF: sterol regulatory element binding transcription factor; TNFRSF10B/DR5: TNF receptor superfamily member 10b; TRAF6: TNF receptor associated factor 6; UPR: unfolded protein response; WAT: white adipose tissue; XBP1: X-box binding protein 1.
DOI: 10.1080/15548627.2020.1757955

Strategy ID Therapy Strategy Synonyms Therapy Targets Therapy Drugs
S01 Improve insulin resistance insulin sensitizer; insulin resistance; glucose tolerance Biguanide: increases 5-AMP activated protein kinase signaling; SGLT-2 inhibitor; Thiazalidinedione: selective PPAR-γ agonists; GLP-1 agonist Metformin; Empagliflozin; Canagliflozin; Rosiglitazone; Pioglitazone; Liraglutide Details
S07 Anti-lipogenesis de novo lipogenesis; de novo lipogenesis; DNL; anti-lipogenic mechanisms; adipogenesis; anti-obesity stearoyl-CoA desaturase 1 (SCD-1); Acetyl-coenzyme carboxylase; acyl-CoA carboxylase inhibitor (ACC inhibitor); stearoyl Coenzyme A desaturase inhibitor (SCD inhibitor); THR-beta selective agonist; DGAT2 inhibitor; FASN inhibitor Aramchol; Firsocostat (GS-0976); VK-2809; ION 224 Details

Target ID Target Name GENE Action Class UniProtKB ID Entry Name
T08 Tumor necrosis factor TNF inhibitor Cytokine P01375 TNFA_HUMAN Details
T41 X-box-binding protein 1 XBP1 inhibitor Protein P17861 XBP1_HUMAN Details
T10 Caspase-1 CASP1 inhibitor Enzyme P29466 CASP1_HUMAN Details
T15 3-hydroxy-3-methylglutaryl-coenzyme A reductase HMGCR inhibitor Enzyme P04035 HMDH_HUMAN Details
T18 Acetyl-CoA carboxylase 1 ACACA inhibitor Enzyme Q13085 ACACA_HUMAN Details
T20 Fatty acid synthase FASN inhibitor Enzyme P49327 FAS_HUMAN Details
T22 Stearoyl-CoA desaturase SCD inhibitor Enzyme O00767 SCD_HUMAN Details

Diseases ID DO ID Disease Name Definition Class
I13 3146 Lipid metabolism disorder An inherited metabolic disorder that involves the creation and degradation of lipids. http://en.wikipedia.org/wiki/Lipid_metabolism disease of metabolism/ inherited metabolic disorder Details
I05 9352 Type 2 diabetes mellitus A diabetes that is characterized by chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action, or both. A diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. http://en.wikipedia.org/wiki/Diabetes, http://en.wikipedia.org/wiki/Diabetes_mellitus_type_2 disease of metabolism/inherited metabolic disorder/ carbohydrate metabolic disorder/glucose metabolism disease/diabetes/ diabetes mellitus Details
I14 9970 Obesity An overnutrition that is characterized by excess body fat, traditionally defined as an elevated ratio of weight to height (specifically 30 kilograms per meter squared), has_material_basis_in a multifactorial etiology related to excess nutrition intake, decreased caloric utilization, and genetic susceptibility, and possibly medications and certain disorders of metabolism, endocrine function, and mental illness. https://en.wikipedia.org/wiki/Obesity disease of metabolism/acquired metabolic disease/ nutrition disease/overnutrition Details

Drug ID Drug Name Type DrugBank ID Targets Category Latest Progress
D387 Vitamin D Supplement DB11094 -- Vitamin source drug Under clinical trials Details
D612 Rapamycin Miscellany -- Immunosuppressants; Methylmalonyl CoA mutase stimulants; MTOR protein inhibitors; T lymphocyte inhibitors -- Under investigation Details
D328 Serine Chemical drug DB00133 SRR Improve insulin resistance Under clinical trials Details
D182 Insulin Biological drug DB00030 INSR agonist; CPE modulator&product of -- Under clinical trials Details
D248 Obeticholic Acid Chemical drug DB05990 NR1H4 activator; NR1H4 agonist; FXR agonist Enhance lipid metabolism Approval rejected Details
D316 S-adenosyl-L-methionine Chemical drug DB00118 GNMT cofactor Antiviral Under clinical trials Details
D223 Metabolic Cofactor Supplementation Supplement -- -- -- Under clinical trials Details