Mechanistic Study On How ANGPTL8 Regulates The Inflammatory Pathway Through Oligomerization

The inflammatory response is closely related to many diseases,such as diabetes,inflammatory enteritis,and even participates in the occurrence and development of tumors.The nuclear factor-kB(NF-kB),which is widely distributed in the body,is an extremely important regulatory factor in the signal path of the inflammatory response.Functional abnormalities of NF-kB are associated with many diseases,such as bone and joint defects and hemoglobin immunodeficiency syndrome.Inhibitory protein kinase complexes(IKK complex)play an important role in regulating NF-kB signaling pathways.IKK complex is composed of IKKa,IKKb and IKK?.IKK? has an important role in IKK complexes and NF-kB signaling pathway.The dysfunction of IKK? is closely related with several diseases,such as pigment incontinence,no sweat ectoderm dysplasia,etc.We previously found that angiogenin like-8(ANGPTL8)can degrade IKK? through autophagy,thus negatively regulates(45)F-k(33)inflammatory signaling pathway.Protein oligomerization and macromolecular protein complexes can be found in autophagy pathway.In order to explore whether ANGPTL8 will form oligomers to degrade IKK?,we examined the interaction domain between ANGPTL8,IKK? and p62.Firstly,the results showed that(32)(45)GPTL8,IKK?,p(21)(17)colocalize in cells,indicates that these three molecules may co-exist in the form of aggregates.To verify the aggregation property of ANGPTL8,we used a series of experiments to demonstrate the aggregation property of ANGPTL8 in vitro.The results showed that ANGPTL8 incubated in vitro could form macromolecular oligomers and insoluble fibrous structure.We constructed six differently truncated ANGPTL8 mutants.By using immunoprecipitation and size-exclusion chromatography,we demonstrated that ANGPTL8 could self-oligomerize and degrade IKK? through the residue 26-70 fragment.Moreover,we found that ANGPTL8 interact with p62 with its residue 70-141 domain.Together,this study provides molecular insights on the functions of ANGPTL8,the oligomerization of ANGPTL8 is critical for its regulation of inflammatory pathways,and suggests that the intrinsic link between inflammatory and metabolic diseases may provide a new angle for the treatment of metabolic diseases.