Upregulation of the klotho gene expression by thyroid hormone and during adipose differentiation in 3T3-L1 adipocytes

A defect in the klotho gene expression in mice leads to a syndrome resembli ng human aging. The klotho gene encodes a single membrane protein whose ext racellular domain carries homology to beta -glucosidases. However, either i ts function or regulatory mechanism of the gene expression still remains un known. In the present study, we investigated the klotho gene expression in 3T3-L1 adipocytes using quantitative reverse transcription-polymerase chain reaction. Both membrane and secreted forms of the klotho gene were express ed in 3T3-L1 preadipocytes. Accompanied with adipose differentiation, not t he secreted form but the membrane form was gradually increased. In 3T3-L1 a dipocytes, triiodothyronine significantly increased the expression levels o f membrane form of the klotho gene, These results suggest that the expressi on of membrane and secreted forms of klotho transcripts are regulated by di fferent mechanisms and that the klotho gene product may play a role in adip ose differentiation. (C) 2001 Elsevier Science Inc. All rights reserved.