Expression and localization of caveolins during postnatal development in rat heart: implication of thyroid hormone.
Caveolins modulate signaling pathways involved in cardiac development. Caveolin-1 exists in two isoforms: the beta-isoform derivates from an alternative translational start site that creates a protein truncated by 31 amino acids, mainly expressed in endothelial cells, whereas caveolin-3 is present in muscle cells. Our aim was to define caveolin distribution and expression during cardiac postnatal development using immunofluorescence and Western blotting. Caveolin-3 sarcolemmal labeling appeared as dotted lines from days 1 to 5 and as continuous lines after 14 days of age. Caveolin-3 expression, low at birth, increased (4-fold) to reach a maximum (P < 0.05) by day 5 and then decreased to stabilize in adults. Total caveolin-1 and its alpha-isoform were codistributed at birth in endothelial and smooth muscle cells; afterward, only the caveolin-1alpha labeling became limited to endothelium. Quantitative analysis indicated a similar temporal pattern of both total caveolin-1 and caveolin-1alpha expression, suggesting that caveolin-1alpha and -1beta are coregulated; the caveolin-1alpha levels increased fourfold by day 5 to reach a maximum by day 14 (P < 0.05). Tyrosine-14-caveolin-1 phosphorylation, low at birth, increased suddenly around day 14 (8-fold vs. day 1) and returning afterward to basal level. Because the T3/T4 level is maximal by day 14, caveolin-1 expression/phosphorylation profiles were analyzed in hypothyroid heart. The levels of caveolin-1alpha and consequently tyrosine-14-caveolin-1 phosphorylation, but not that of caveolin-3, decreased (50%) in hypothyroid 14-day-old rats. Our data demonstrate that, during postnatal cardiac growth, 1) caveolins are distinctly regulated, and 2) thyroid hormones are involved in caveolin-1alpha expression.
Ratajczak
Philippe
P
CRCIL U689, IFR139, Hôpital Lariboisière, 41 Boulevard de la Chapelle, 75475 Paris Cedex 10, France.
Oliviéro
Patricia
P
Marotte
Françoise
F
Kolar
Frantisek
F
Ostadal
Bohuslav
B
Samuel
Jane-Lise
JL
D000222:Adaptation, Physiological; D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D022461:Caveolins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006321:Heart / Q000196:embryology / Q000254:growth & development*; D007037:Hypothyroidism / Q000139:chemically induced / Q000196:embryology / Q000378:metabolism*; D008779:Methylthiouracil; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013963:Thyroid Hormones / Q000378:metabolism*; D014018:Tissue Distribution
D022461:Caveolins; D013963:Thyroid Hormones; D008779:Methylthiouracil