Regulation of secreted protein acidic and rich in cysteine during adipose conversion and adipose tissue hyperplasia.
OBJECTIVE
To explore the regulation of secreted protein acidic and rich in cysteine (SPARC) expression and its role in adipose tissue.


METHODS
We studied the regulation of SPARC expression in transgenic mice expressing the human beta3 and alpha2 adrenergic receptors on a murine beta3 adrenergic receptor null background that became obese under a high-fat diet mainly as a result of adipose tissue hyperplasia. Furthermore, we analyzed its expression in human adipose tissue and its regulation during adipocyte differentiation.


RESULTS
SPARC protein in adipose tissue was increased in obese transgenic mice compared with control mice, indicating that SPARC expression was associated with adipose tissue hyperplasia. Both SPARC mRNA and protein were detected in human adipose tissue. Comparing adipocytes and vascular stroma, we found that SPARC expression was mainly associated with the adipocyte fraction. Consistent with this, SPARC transcript increased during differentiation of human primary preadipocytes. 3T3-L1 preadipocytes showed an increase in SPARC expression in differentiated cells but with biphasic expression during the process. After induction in committed cells, SPARC mRNA and protein levels declined as differentiation began and returned to elevated levels in fully differentiated adipocytes.


CONCLUSIONS
SPARC expression correlated with adipose tissue hyperplasia and adipogenesis. Therefore, SPARC seems to play a role in adipose tissue physiology as it is involved in growth and differentiation.
Chavey
Carine
C
Institut National de la Santé et de la Recherche Médicale U145, IFR 50, Avenue de Valombrose, 06107 Nice Cedex 2, France. vanobbeg@unice.fr.
Boucher
Jérémie
J
Monthouël-Kartmann
Marie-Noëlle
MN
Sage
E Helene
EH
Castan-Laurell
Isabelle
I
Valet
Philippe
P
Tartare-Deckert
Sophie
S
Van Obberghen
Emmanuel
E
D017667:Adipocytes / Q000378:metabolism*; D050156:Adipogenesis / Q000502:physiology*; D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009765:Obesity / Q000378:metabolism*; D015676:Osteonectin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
D015676:Osteonectin; D012333:RNA, Messenger