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KMID : 0620920190510080089
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Experimental & Molecular Medicine
2019 Volume.51 No. 8 p.89 ~ p.89
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Altered adipocyte differentiation and unbalanced autophagy in type 2 Familial Partial Lipodystrophy: an in vitro and in vivo study of adipose tissue browning
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Pellegrini Camilla
Columbaro Marta
Schena Elisa
Prencipe Sabino
Andrenacci Davide
Iozzo Patricia
Guzzardi Maria Angela
Capanni Cristina
Mattioli Elisabetta
Loi Manuela
Araujo-Vilar David
Squarzoni Stefano
Cinti Saverio
Morselli Paolo
Giorgetti Assuero
Zanotti Laura
Gambineri Alessandra
Lattanzi Giovanna
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Abstract
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Type-2 Familial Partial Lipodystrophy is caused by LMNA mutations. Patients gradually lose subcutaneous fat from the limbs, while they accumulate adipose tissue in the face and neck. Several studies have demonstrated that autophagy is involved in the regulation of adipocyte differentiation and the maintenance of the balance between white and brown adipose tissue. We identified deregulation of autophagy in laminopathic preadipocytes before induction of differentiation. Moreover, in differentiating white adipocyte precursors, we observed impairment of large lipid droplet formation, altered regulation of adipose tissue genes, and expression of the brown adipose tissue marker UCP1. Conversely, in lipodystrophic brown adipocyte precursors induced to differentiate, we noticed activation of autophagy, formation of enlarged lipid droplets typical of white adipocytes, and dysregulation of brown adipose tissue genes. In agreement with these in vitro results indicating conversion of FPLD2 brown preadipocytes toward the white lineage, adipose tissue from FPLD2 patient neck, an area of brown adipogenesis, showed a white phenotype reminiscent of its brown origin. Moreover, in vivo morpho-functional evaluation of fat depots in the neck area of three FPLD2 patients by PET/CT analysis with cold stimulation showed the absence of brown adipose tissue activity. These findings highlight a new pathogenetic mechanism leading to improper fat distribution in lamin A-linked lipodystrophies and show that both impaired white adipocyte turnover and failure of adipose tissue browning contribute to disease.
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KEYWORD
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Macroautophagy, Mechanisms of disease, Metabolic syndrome, Nuclear envelope, Translational research
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