Klotho protein promotes adipocyte differentiation.
Mice with homozygous disruption of the klotho exhibit multiple age-related disorders and have barely detectable amounts of white adipose tissue. Although klotho expression in cultured adipocytes has been reported, little is known about its function in adipocytes. In the present study, we investigated the role of klotho on adipocyte differentiation. Adipocyte differentiation was induced by incubation of confluent 3T3-L1 cells with insulin, dexamethasone, and 1-methyl-3-isobutyl-xanthin. Klotho-siRNA and expression vector were produced for klotho suppression and overexpression, respectively. Klotho protein was purified for determination of the hormonal effect of klotho. Klotho mRNA and protein expression increased up to the 3rd d of differentiation. A peroxisome proliferator-activated receptor-gamma agonist increased klotho expression during the early period of adipocyte differentiation. The mRNA expression of adipocyte differentiation markers, such as CCAAT/enhancer-binding protein (C/EBP)alpha, C/EBPbeta, C/EBPdelta, peroxisome proliferator-activated receptor-gamma, and fatty acid binding protein 4, was decreased by klotho suppression, and increased 1.9- to 3.8-fold by klotho overexpression. The results of Oil Red O staining also suggested that klotho overexpression promoted adipocyte differentiation. Klotho protein stimulation resulted in a 2.4- to 4.6-fold increase in mRNA expression of differentiation markers compared with control, and the time course depended on adipocyte induction status. Western blot analysis showed that protein levels of C/EBPalpha and C/EBPdelta were increased by Klotho protein stimulation. These results suggest that klotho works as a hormonal factor to promote adipocyte differentiation in the early days, during the period of transient proliferation in the differentiation process, and that klotho may play an essential role in adipocyte differentiation.
Chihara
Yukana
Y
Department of Geriatric Medicine, Osaka University Graduate School of Medicine, 2-2, Yamada-oka, Number B6, Suita, Osaka 565-0871, Japan.
Rakugi
Hiromi
H
Ishikawa
Kazuhiko
K
Ikushima
Masashi
M
Maekawa
Yoshihiro
Y
Ohta
Junsuke
J
Kida
Iwao
I
Ogihara
Toshio
T
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000502:physiology*; D000818:Animals; D001391:Azo Compounds; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D004396:Coloring Agents; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005966:Glucuronidase / Q000235:genetics* / Q000378:metabolism*; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D000090265:Klotho Proteins; D051379:Mice; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering
D001391:Azo Compounds; D015415:Biomarkers; D004396:Coloring Agents; D047495:PPAR gamma; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D005993:Glycerolphosphate Dehydrogenase; D005966:Glucuronidase; D000090265:Klotho Proteins; C011049:oil red O