P311 binds to the latency associated protein and downregulates the expression of TGF-beta1 and TGF-beta2.
P311 is an 8-kDa protein originally found in neurons and muscle. We recently showed that expression of P311 in NIH 3T3 cells induced a myofibroblast phenotype with low TGF-beta1 expression. Here we demonstrate that P311 downregulates not only TGF-beta1, but also TGF-beta2, expression, with no effect on TGF-beta3. In addition, P311 interacts with TGF-beta2 in a yeast two-hybrid system through a sequence encompassing part of the TGF-beta latent associated protein (LAP) and part of mature TGF-beta2. Coimmunoprecipitations demonstrated interaction between P311 and TGF-beta1 and 2, but not TGF-beta3. Additional coimmunoprecipitations after introducing LAP or mature TGF-beta1 into cells demonstrated P311 binding to LAP, but not to mature TGF-beta. P311 has a conserved PEST domain, which generally serves as a rapid degradation signal. Deletion of the PEST domain reversed the effect of P311 on TGF-beta isoforms. Finally, Smad3 activity was decreased in P311-expressing cells, but was corrected by exogenous TGF-beta1 treatment, which also elevated TGF-beta1 mRNA level. This suggested that P311 downregulates TGF-beta1 and 2 in part by blocking TGF-beta autoinduction.
Department of Pathology, Wayne State University, School of Medicine, Detroit, MI, USA.
Seema
S
Paliwal
Jinghua
J
Shi
Urmil
U
Dhru
Yuanxiang
Y
Zhou
Lucia
L
Schuger
D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D005822:Genetic Vectors; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011233:Precipitin Tests; D020033:Protein Isoforms; D011498:Protein Precursors / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D053773:Transforming Growth Factor beta1; D020798:Two-Hybrid System Techniques; D015003:Yeasts / Q000235:genetics
D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D015513:Oncogene Proteins; D010446:Peptide Fragments; D020033:Protein Isoforms; D011498:Protein Precursors; D012333:RNA, Messenger; D011994:Recombinant Proteins; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1