Extracellular matrix protein fibulin-2 is expressed in the embryonic endocardial cushion tissue and is a prominent component of valves in adult heart.
Fibulins-1 and -2 are two recently characterized extracellular matrix proteins of a novel protein family. They are found in many tissues in the adult stage, but several differences in their expression patterns were noted in cultured cells and adult tissues. Fibulin-1 is particularly well expressed in the endocardial cushion tissue (ECT) during embryogenesis and we therefore compared the expression patterns of fibulin-1 and -2 in the developing mouse heart. Antibodies against mouse fibulin-1 and -2 were used in immunofluorescence, and the expression of mRNAs were studied with synthetic oligonucleotides by in situ hybridization. A striking codistribution of fibulin-1 and -2 was seen at all stages of the development of the endocardial cushion tissue. Fibulin-2 was found to be a more specific marker for the embryonic ECT than fibulin-1, which was also transiently expressed in cardiac muscle. Immunofluorescence showed that the fibulins remained expressed in valves of the heart in the adult stage. The results suggest a role of the two fibulins in the development of the ECT and in the maintenance of the tensile strength of the cardiac valves.
Department of Animal Physiology, Uppsala University, Sweden.
H Y
HY
Zhang
M L
ML
Chu
T C
TC
Pan
T
T
Sasaki
R
R
Timpl
P
P
Ekblom
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000032:analysis* / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000032:analysis* / Q000235:genetics; D005260:Female; D006321:Heart / Q000196:embryology*; D006351:Heart Valves / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits
D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; C084612:fibulin 2