Journal
METABOLISM-CLINICAL AND EXPERIMENTAL
Volume 114, Issue -, Pages -Publisher
W B SAUNDERS CO-ELSEVIER INC
DOI: 10.1016/j.metabol.2020.154430
Keywords
Adipose tissue; Endotrophin; Inflammation; Adipogenesis; Adipocyte lipolysis; Collagen
Categories
Funding
- Korea Health Technology R&D Project through the Korea Health Industry Development Institute [KHIDI] [HI14C1277]
- Bio-Synergy Research Project of the Ministry of Science, ICT and Future Planning [2017M3A9C4065956]
- Basic Science Research Program through the National Research Foundation [2018R1A2B6003878, 2018R1A5A1024340, 2020R1A2C4001503]
- PhD Student Research Fellowship of the Ministry of Education [2020R1A6A3A13066592]
- Korea Mouse Phenotyping Center [2014M3A9D5A01074636, 2014M3A9D5A01075128]
- National Research Foundation of Korea [2014M3A9D5A01075128, 2020R1A2C4001503, 2014M3A9D5A01074636, 2018R1A2B6003878] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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The study reveals the crucial role of Col6a3 in mature adipocyte differentiation, inflammation, lipolysis, and insulin sensitivity.
Objective: Obesity-induced adipose tissue remodeling is closely associated with systemic insulin resistance. However, the mechanistic involvement of adipocyte-derived extracellular matrix proteins under pathophysiological conditions remains unclear. Our aim was to investigate the distinctive contributions of each chain of type VI collagens (Col6) and its cleavage protein endotrophin to adipocyte functions and insulin sensitivity. Methods: Col6 comprises three alpha chains: Col6a1, Col6a2, and Col6a3. We generated Col6a1-, Col6a2-, and Col6a3-deficient 3T3-L1 adipocytes using the CRISPR-Cas9 system as well as a novel Col6a3-deficient (Col6a3KO) mouse model for loss-of-function studies. Adenoviral-endotrophin and adipocyte-specific doxycycline-inducible endotrophin transgenic mice were utilized for the gain-of-function analysis. Results: The holo-Col6 fibrils were found to be required for mature adipocyte differentiation. Only Col6a3-deficient 3T3-L1 adipocytes showed decreased inflammation and basal adipocyte lipolysis and prevented ER-stress-induced insulin resistance. Consistently, Col6a3KO mice showed decreased adipocyte size and fat mass of epididymal adipose tissues due to a defect in adipogenic and lipolytic capacity of adipocytes. Beyond the structural role of Col6a3, over expression of endotrophin in obese mice further augmented insulin resistance, which was tightly associated with a significant increase in lipolysis, inflammation, and cellular apoptosis in adipose tissues, whereas this showed a limited effect on adipogenesis. Conclusions: These novel findings corroborate our previous observations suggesting that adipose tissue extracellular matrix regulates adipocyte function and insulin sensitivity in pathophysiological conditions. Mechanistically, holoCol6 fibrils and their signaling derivative endotrophin govern adipocyte function independently of their role as structural supports via MAPK signaling pathways, and the latter could be an important metabolic effector in obesity-related metabolic diseases. (C) 2020 Elsevier Inc. All rights reserved.
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