TY - JOUR
T1 - Transforming growth factor-β1 regulates fibronectin isoform expression and splicing factor SRp40 expression during ATDC5 chondrogenic maturation
AU - Han, Fei
AU - Gilbert, James R.
AU - Harrison, Gerald
AU - Adams, Christopher S.
AU - Freeman, Theresa
AU - Tao, Zhuliang
AU - Zaka, Raihana
AU - Liang, Hongyan
AU - Williams, Charlene
AU - Tuan, Rocky S.
AU - Norton, Pamela A.
AU - Hickok, Noreen J.
N1 - Funding Information:
This work was supported by NIH grants AR45181 (N.J.H.) AR44360 (C.J.W.), AR39740 (C.J.W. and N.J.H.), AR46821 (P.A.N.), DE-13310 (C.S.A.), DE-10875 (C.S.A.), and DE-05748 (C.S.A.). We also gratefully acknowledge sponsorship of this work by the Department of the Army, Award #DAMD17-03-1-0713 (N.J.H., T.F. and C.S.A.). The U.S. Army Medical Research Acquisition Activity, 820 Chandler Street, Fort Detrick MD 21702-5014 is the awarding and administering acquisition office.
PY - 2007/5/1
Y1 - 2007/5/1
N2 - Fibronectin (FN) isoform expression is altered during chondrocyte commitment and maturation, with cartilage favoring expression of FN isoforms that includes the type II repeat extra domain B (EDB) but excludes extra domain A (EDA). We and others have hypothesized that the regulated splicing of FN mRNAs is necessary for the progression of chondrogenesis. To test this, we treated the pre-chondrogenic cell line ATDC5 with transforming growth factor-β1, which has been shown to modulate expression of the EDA and EDB exons, as well as the late markers of chondrocyte maturation; it also slightly accelerates the early acquisition of a sulfated proteoglycan matrix without affecting cell proliferation. When chondrocytes are treated with TGF-β1, the EDA exon is preferentially excluded at all times whereas the EDB exon is relatively depleted at early times. This regulated alternative splicing of FN correlates with the regulation of alternative splicing of SRp40, a splicing factor facilitating inclusion of the EDA exon. To determine if overexpression of the SRp40 isoforms altered FN and FN EDA organization, cDNAs encoding these isoforms were overexpressed in ATDC5 cells. Overexpression of the long-form of SRp40 yielded an FN organization similar to TGF-β1 treatment; whereas overexpression of the short form of SRp40 (which facilitates EDA inclusion) increased formation of long-thick FN fibrils. Therefore, we conclude that the effects of TGF-β1 on FN splicing during chondrogenesis may be largely dependent on its effect on SRp40 isoform expression.
AB - Fibronectin (FN) isoform expression is altered during chondrocyte commitment and maturation, with cartilage favoring expression of FN isoforms that includes the type II repeat extra domain B (EDB) but excludes extra domain A (EDA). We and others have hypothesized that the regulated splicing of FN mRNAs is necessary for the progression of chondrogenesis. To test this, we treated the pre-chondrogenic cell line ATDC5 with transforming growth factor-β1, which has been shown to modulate expression of the EDA and EDB exons, as well as the late markers of chondrocyte maturation; it also slightly accelerates the early acquisition of a sulfated proteoglycan matrix without affecting cell proliferation. When chondrocytes are treated with TGF-β1, the EDA exon is preferentially excluded at all times whereas the EDB exon is relatively depleted at early times. This regulated alternative splicing of FN correlates with the regulation of alternative splicing of SRp40, a splicing factor facilitating inclusion of the EDA exon. To determine if overexpression of the SRp40 isoforms altered FN and FN EDA organization, cDNAs encoding these isoforms were overexpressed in ATDC5 cells. Overexpression of the long-form of SRp40 yielded an FN organization similar to TGF-β1 treatment; whereas overexpression of the short form of SRp40 (which facilitates EDA inclusion) increased formation of long-thick FN fibrils. Therefore, we conclude that the effects of TGF-β1 on FN splicing during chondrogenesis may be largely dependent on its effect on SRp40 isoform expression.
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U2 - 10.1016/j.yexcr.2007.01.028
DO - 10.1016/j.yexcr.2007.01.028
M3 - Article
C2 - 17391668
AN - SCOPUS:34247139808
SN - 0014-4827
VL - 313
SP - 1518
EP - 1532
JO - Experimental Cell Research
JF - Experimental Cell Research
IS - 8
ER -