Differentiation-dependent expression of retinoid-binding proteins in BFC-1 beta adipocytes
Recently, we demonstrated that adipose tissue plays an important role in retinol storage and retinol-binding protein (RBP) synthesis. Our data suggested that RBP expression in adipose tissue is dependent on the state of adipocyte differentiation. To examine this possibility, we explored the differen...
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Veröffentlicht in: | The Journal of biological chemistry 1992-07, Vol.267 (20), p.13884-13889 |
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Zusammenfassung: | Recently, we demonstrated that adipose tissue plays an important role in retinol storage and retinol-binding protein (RBP)
synthesis. Our data suggested that RBP expression in adipose tissue is dependent on the state of adipocyte differentiation.
To examine this possibility, we explored the differentiation-dependent expression of RBP using BFC-1 beta preadipocytes, which
can be stimulated to undergo adipose differentiation. Total RNA was isolated from undifferentiated (preadipocytes) and differentiated
(adipocytes) BFC-1 beta cells and analyzed by Northern blotting. RBP mRNA was not detected in the preadipocytes, but considerable
RBP mRNA was present in differentiated BFC-1 beta cells. In BFC-1 beta cells, induced to differentiate with insulin and thyroid
hormone, RBP mRNA was first detected after 4 days, reached a maximum level by day 10, and remained at this maximum level for
at least 2 more days. Cellular retinol-binding protein was expressed at low levels in the BFC-1 beta preadipocytes and the
level of expression increased for 6 days after induction to differentiate and slowly declined on later days. Neither the maximum
level of RBP expression nor the day on which this level was reached was influenced by the level of retinol provided in the
BFC-1 beta culture medium. BFC-1 beta cells secreted newly synthesized RBP into the culture medium at a rate of 43 +/- 14
ng RBP/24 h/10(6) adipocytes. When the BFC-1 beta adipocytes were provided 1.0 microM retinol in the medium, they accumulated
the retinol and synthesized retinyl esters. These studies with BFC-1 beta cells confirm that RBP synthesis and secretion and
retinol accumulation are intrinsic properties of differentiated adipocytes. Furthermore, they suggest that RBP and cellular
retinol-binding protein gene expression are regulated as part of a package of genes which are modulated during adipocyte differentiation. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(19)49651-8 |