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FAK induces expression of Prx1 to promote tenascin-C-dependent fibroblast migration.

McKean DM, Sisbarro L, Ilic D, Kaplan-Alburquerque N, Nemenoff R, Weiser-Evans M, Kern MJ, Jones PL - J. Cell Biol. (2003)

Bottom Line: Consistent with the idea that FAK regulates TN-C, migration-defective FAK- cells expressed reduced levels of TN-C.Furthermore, expression of FAK in FAK- fibroblasts induced TN-C, whereas inhibition of FAK activity in FAK-wild-type cells had the opposite effect.These results appear to be relevant in vivo because Prx1 and TN-C expression levels were reduced in FAK- embryos.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, USA.

ABSTRACT
Fibroblast migration depends, in part, on activation of FAK and cellular interactions with tenascin-C (TN-C). Consistent with the idea that FAK regulates TN-C, migration-defective FAK- cells expressed reduced levels of TN-C. Furthermore, expression of FAK in FAK- fibroblasts induced TN-C, whereas inhibition of FAK activity in FAK-wild-type cells had the opposite effect. Paired-related homeobox 1 (Prx1) encodes a homeobox transcription factor that induces TN-C by interacting with a binding site within the TN-C promoter, and it also promotes fibroblast migration. Therefore, we hypothesized that FAK regulates TN-C by controlling the DNA-binding activity of Prx1 and/or by inducing Prx1 expression. Prx1-homeodomain binding site complex formation observed with FAK-wild-type fibroblasts failed to occur in FAK- fibroblasts, yet expression of Prx1 in these cells induced TN-C promoter activity. Thus, FAK is not essential for Prx1 DNA-binding activity. However, activated FAK was essential for Prx1 expression. Functionally, Prx1 expression in FAK- fibroblasts restored their ability to migrate toward fibronectin, in a manner that depends on TN-C. These results appear to be relevant in vivo because Prx1 and TN-C expression levels were reduced in FAK- embryos. This paper suggests a model whereby FAK induces Prx1, and subsequently the formation of a TN-C-enriched ECM that contributes to fibroblast migration.

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Expression of TN-C and Prx1 in FAK- embryos. (A) Semi-quantitative RT-PCR assays to compare the steady-state levels of TN-C, Prx1, and β-actin mRNAs in FAK–wild-type (+) and - (−) E8.5 embryos. (B) Representative fluorescence micrographs showing immunostaining of headfold region of FAK–wild-type (+) and - (−) E8.5 embryos for TN-C (green). Two different sections are shown. Bar, 20 μm.
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fig7: Expression of TN-C and Prx1 in FAK- embryos. (A) Semi-quantitative RT-PCR assays to compare the steady-state levels of TN-C, Prx1, and β-actin mRNAs in FAK–wild-type (+) and - (−) E8.5 embryos. (B) Representative fluorescence micrographs showing immunostaining of headfold region of FAK–wild-type (+) and - (−) E8.5 embryos for TN-C (green). Two different sections are shown. Bar, 20 μm.

Mentions: To determine whether our tissue culture studies were relevant in vivo, we evaluated Prx1 and TN-C expression in FAK–wild-type and - mouse embryos, harvested at E8.5–9.0. Prx1 and TN-C mRNA expression was reduced in FAK- embryos compared with their age-matched, FAK–wild-type counterparts (Fig. 7 A). Parallel immunofluorescence studies of FAK–wild-type and - embryos showed that TN-C protein expression is also reduced in FAK- embryos (Fig. 7 B). Thus, expression of Prx1 and TN-C appears to depend on FAK during embryonic development.


FAK induces expression of Prx1 to promote tenascin-C-dependent fibroblast migration.

McKean DM, Sisbarro L, Ilic D, Kaplan-Alburquerque N, Nemenoff R, Weiser-Evans M, Kern MJ, Jones PL - J. Cell Biol. (2003)

Expression of TN-C and Prx1 in FAK- embryos. (A) Semi-quantitative RT-PCR assays to compare the steady-state levels of TN-C, Prx1, and β-actin mRNAs in FAK–wild-type (+) and - (−) E8.5 embryos. (B) Representative fluorescence micrographs showing immunostaining of headfold region of FAK–wild-type (+) and - (−) E8.5 embryos for TN-C (green). Two different sections are shown. Bar, 20 μm.
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Related In: Results  -  Collection

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fig7: Expression of TN-C and Prx1 in FAK- embryos. (A) Semi-quantitative RT-PCR assays to compare the steady-state levels of TN-C, Prx1, and β-actin mRNAs in FAK–wild-type (+) and - (−) E8.5 embryos. (B) Representative fluorescence micrographs showing immunostaining of headfold region of FAK–wild-type (+) and - (−) E8.5 embryos for TN-C (green). Two different sections are shown. Bar, 20 μm.
Mentions: To determine whether our tissue culture studies were relevant in vivo, we evaluated Prx1 and TN-C expression in FAK–wild-type and - mouse embryos, harvested at E8.5–9.0. Prx1 and TN-C mRNA expression was reduced in FAK- embryos compared with their age-matched, FAK–wild-type counterparts (Fig. 7 A). Parallel immunofluorescence studies of FAK–wild-type and - embryos showed that TN-C protein expression is also reduced in FAK- embryos (Fig. 7 B). Thus, expression of Prx1 and TN-C appears to depend on FAK during embryonic development.

Bottom Line: Consistent with the idea that FAK regulates TN-C, migration-defective FAK- cells expressed reduced levels of TN-C.Furthermore, expression of FAK in FAK- fibroblasts induced TN-C, whereas inhibition of FAK activity in FAK-wild-type cells had the opposite effect.These results appear to be relevant in vivo because Prx1 and TN-C expression levels were reduced in FAK- embryos.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, USA.

ABSTRACT
Fibroblast migration depends, in part, on activation of FAK and cellular interactions with tenascin-C (TN-C). Consistent with the idea that FAK regulates TN-C, migration-defective FAK- cells expressed reduced levels of TN-C. Furthermore, expression of FAK in FAK- fibroblasts induced TN-C, whereas inhibition of FAK activity in FAK-wild-type cells had the opposite effect. Paired-related homeobox 1 (Prx1) encodes a homeobox transcription factor that induces TN-C by interacting with a binding site within the TN-C promoter, and it also promotes fibroblast migration. Therefore, we hypothesized that FAK regulates TN-C by controlling the DNA-binding activity of Prx1 and/or by inducing Prx1 expression. Prx1-homeodomain binding site complex formation observed with FAK-wild-type fibroblasts failed to occur in FAK- fibroblasts, yet expression of Prx1 in these cells induced TN-C promoter activity. Thus, FAK is not essential for Prx1 DNA-binding activity. However, activated FAK was essential for Prx1 expression. Functionally, Prx1 expression in FAK- fibroblasts restored their ability to migrate toward fibronectin, in a manner that depends on TN-C. These results appear to be relevant in vivo because Prx1 and TN-C expression levels were reduced in FAK- embryos. This paper suggests a model whereby FAK induces Prx1, and subsequently the formation of a TN-C-enriched ECM that contributes to fibroblast migration.

Show MeSH