cDNA cloning and chromosomal mapping of rat Smad2 and Smad4 and their expression in cultured rat articular chondrocytes.
Smad proteins are known to transduce signalling of TGF-beta receptor superfamily. We report here the entire sequences of rat Smad2 and Smad4 which have not been identified yet. Entire sequences were identified by degenerated polymerase chain reaction and following phage library screening and 5' RACE. The predicted amino acid sequences of rat Smad2 and Smad4 are highly conserved among rat, human and mouse. We also mapped these Smads to chromosome 18q.12.3. Unlike endothelial cells, TGF-beta1 stimulates articular chondrocyte proliferation as well as extracellular matrix production, and acts as a repairing agent against cartilage destruction. Since both Smad2 and Smad4 are essential factors for TGF-beta signalling, we examined their expression and regulation in cultured articular chondrocytes. Northern blot analysis showed that TGF-beta1 significantly increased the mRNA level of Smad2 but not of Smad4 in a dose- and time-dependent manner, suggesting that the augmentation of TGF-beta1 action is caused by increasing the expression of the downstream signalling molecule.
Osaki
M
M
Department of Orthopaedic Surgery, Nagasaki University School of Medicine, Japan.
Tsukazaki
T
T
Ono
N
N
Yonekura
A
A
Hirota
Y
Y
Miyazaki
Y
Y
Shindo
H
H
Sonta
S
S
Yamashita
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002358:Cartilage, Articular / Q000737:chemistry / Q000378:metabolism*; D019902:Chondrocytes / Q000737:chemistry / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D051899:Smad2 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics*
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; C497796:SMAD4 protein, human; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; C497784:Smad2 protein, rat; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; C490811:Smad4 protein, rat; D015534:Trans-Activators