title: Visfatin is released from 3T3-L1 adipocytes via a non-classical pathway.
abstract: Visfatin is a secretory protein which exerts insulin mimetic and proinflammatory effects, also functioning as an intracellular enzyme to produce NAD. Plasma visfatin levels and visfatin mRNA expression in adipose tissues are increased in obese subjects. Visfatin does not have a decent cleavable signal sequence, and the mechanism, that mediates release of visfatin from adipocytes, remains poorly understood. In this study, we demonstrate that visfatin is released abundantly into culture medium from 3T3-L1 adipocytes. Subcellular fractionation analysis showed that visfatin was localized in the cytosol, but not in nucleus, membrane, vesicles, or mitochondria fractions. Visfatin release was not reduced by Brefeldin A and Monensin, inhibitors of endoplasmic reticulum (ER)-Golgi-dependent secretion. In addition, visfatin was not released on microvesicles. These results suggest that visfatin should be released from 3T3-L1 adipocytes via an ER-Golgi or microvesicles independent pathway.
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Maiko
authors.initials: M
authors.lastname: Nozaki
authors.forename: Atsunori
authors.initials: A
authors.lastname: Fukuhara
authors.forename: Katsumori
authors.initials: K
authors.lastname: Segawa
authors.forename: Naohito
authors.initials: N
authors.lastname: Aoki
authors.forename: Morihiro
authors.initials: M
authors.lastname: Matsuda
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Komuro
authors.forename: Iichiro
authors.initials: I
authors.lastname: Shimomura
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007249:Inflammation; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D008985:Monensin / Q000494:pharmacology; D054409:Nicotinamide Phosphoribosyltransferase; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D020126:Brefeldin A; D008985:Monensin; D054409:Nicotinamide Phosphoribosyltransferase; C495867:nicotinamide phosphoribosyltransferase, mouse