Obesity induces adipose fibrosis and collagen cross-linking through suppressing AMPK and enhancing lysyl oxidase expression. 2022

Xiangdong Liu, and Liang Zhao, and Yanting Chen, and Yao Gao, and Qiyu Tian, and Jun Seok Son, and Song Ah Chae, and Jeanene Marie de Avila, and Mei-Jun Zhu, and Min Du
Laboratory of Nutrigenomics and Growth Biology, Department of Animal Sciences, Washington State University, Pullman, USA.

Collagen is the main component of connective tissue surrounding adipocytes. Collagen cross-linking affects adipose remodeling, which is crucial for maintaining function and metabolic homeostasis of adipose tissue. However, the effects of obesity on collagen cross-linking and adipose fibrosis remain to be examined. Therefore, the objective of this study was to investigate obesity-induced collagen cross-linking in adipose tissue and explore the underlying mechanisms. We found that obesity increased mature nonreducible collagen cross-linking in white adipose tissue (WAT) of mice, which was associated with inhibition of AMPK, up-regulation of transforming growth factor-β (TGF-β) signaling and the expression of lysyl oxidase (LOX), a key enzyme catalyzing the synthesis of mature cross-linking products. In SVCs and 3T3-L1 adipocytes, AMPK activation by metformin or AICAR inhibited TGF-β1-induced fibrogenesis and expression of LOX, which was further confirmed by ectopic expression of AMPK WT and K45R mutant. Consistently, in vivo, knocking out AMPK increased fibrosis and collagen cross-linking. Our study showed that AMPK downregulation due to obesity increases TGF-β signaling and LOX expression, which enhances adipose fibrosis and collagen cross-linking. Thus, AMPK is a therapeutic target for ameliorating the obesity-induced fibrosis, improving metabolic health of adipose tissue.

UI MeSH Term Description Entries
D008249 Protein-Lysine 6-Oxidase An enzyme oxidizing peptidyl-lysyl-peptide in the presence of water & molecular oxygen to yield peptidyl-allysyl-peptide plus ammonia & hydrogen peroxide. EC 1.4.3.13. Lysyl Oxidase,Collagen Lysyl Oxidase,6-Oxidase, Protein-Lysine,Lysyl Oxidase, Collagen,Oxidase, Collagen Lysyl,Oxidase, Lysyl,Protein Lysine 6 Oxidase
D009765 Obesity A status with BODY WEIGHT that is grossly above the recommended standards, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).
D003094 Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH). Avicon,Avitene,Collagen Felt,Collagen Fleece,Collagenfleece,Collastat,Dermodress,Microfibril Collagen Hemostat,Pangen,Zyderm,alpha-Collagen,Collagen Hemostat, Microfibril,alpha Collagen
D005355 Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Cirrhosis,Fibroses
D000273 Adipose Tissue Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white. Fatty Tissue,Body Fat,Fat Pad,Fat Pads,Pad, Fat,Pads, Fat,Tissue, Adipose,Tissue, Fatty
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D016212 Transforming Growth Factor beta A factor synthesized in a wide variety of tissues. It acts synergistically with TGF-alpha in inducing phenotypic transformation and can also act as a negative autocrine growth factor. TGF-beta has a potential role in embryonal development, cellular differentiation, hormone secretion, and immune function. TGF-beta is found mostly as homodimer forms of separate gene products TGF-beta1, TGF-beta2 or TGF-beta3. Heterodimers composed of TGF-beta1 and 2 (TGF-beta1.2) or of TGF-beta2 and 3 (TGF-beta2.3) have been isolated. The TGF-beta proteins are synthesized as precursor proteins. Bone-Derived Transforming Growth Factor,Platelet Transforming Growth Factor,TGF-beta,Milk Growth Factor,TGFbeta,Bone Derived Transforming Growth Factor,Factor, Milk Growth,Growth Factor, Milk
D051379 Mice The common name for the genus Mus. Mice, House,Mus,Mus musculus,Mice, Laboratory,Mouse,Mouse, House,Mouse, Laboratory,Mouse, Swiss,Mus domesticus,Mus musculus domesticus,Swiss Mice,House Mice,House Mouse,Laboratory Mice,Laboratory Mouse,Mice, Swiss,Swiss Mouse,domesticus, Mus musculus
D055372 AMP-Activated Protein Kinases Intracellular signaling protein kinases that play a signaling role in the regulation of cellular energy metabolism. Their activity largely depends upon the concentration of cellular AMP which is increased under conditions of low energy or metabolic stress. AMP-activated protein kinases modify enzymes involved in LIPID METABOLISM, which in turn provide substrates needed to convert AMP into ATP. 5'-AMP-Activated Protein Kinase,AMP-Activated Kinase,AMP-Activated Protein Kinase,AMP-Activated Protein Kinase alpha Subunit,AMP-Activated Protein Kinase alpha Subunits,AMP-Activated Protein Kinase beta Subunit,AMP-Activated Protein Kinase beta Subunits,AMP-Activated Protein Kinase gamma Subunit,AMP-Activated Protein Kinase gamma Subunits,PRKAA,5' AMP Activated Protein Kinase,AMP Activated Kinase,AMP Activated Protein Kinase,AMP Activated Protein Kinase alpha Subunit,AMP Activated Protein Kinase alpha Subunits,AMP Activated Protein Kinase beta Subunit,AMP Activated Protein Kinase beta Subunits,AMP Activated Protein Kinase gamma Subunit,AMP Activated Protein Kinase gamma Subunits,AMP Activated Protein Kinases

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