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CtBP1 overexpression in keratinocytes perturbs skin homeostasis.

Deng H, Li F, Li H, Deng Y, Liu J, Wang D, Han G, Wang XJ, Zhang Q - J. Invest. Dermatol. (2013)

Bottom Line: Surprisingly, K5.CtBP1 pups also exhibited a hair loss phenotype.Molecular studies revealed that CtBP1 directly suppressed Dlx3 transcription.In summary, this CtBP1 transgenic model provides in vivo evidence for certain CtBP1 functions predicted from in vitro studies, reveals--to our knowledge--previously unreported functions and transcriptional activities of CtBP1 in the context of epithelial-mesenchymal interplay, and suggests that CtBP1 has a pathogenic role in hair follicle morphogenesis and differentiation.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Dermatology, University of Colorado Denver, Aurora, Colorado, USA [2] Department of Pathology, University of Colorado Denver, Aurora, Colorado, USA [3] Department of Dermatology, The Sixth People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China.

ABSTRACT
Carboxyl-terminal-binding protein-1 (CtBP1) is a transcriptional corepressor with multiple in vitro targets, but its in vivo functions are largely unknown. We generated keratinocyte-specific CtBP1 transgenic mice with a keratin-5 promoter (K5.CtBP1) to probe the pathological roles of CtBP1. At transgene expression levels comparable to endogenous CtBP1 in acute skin wounds, the K5.CtBP1 epidermis displayed hyperproliferation, loss of E-cadherin, and failed terminal differentiation. Known CtBP1 target genes associated with these processes, e.g., p21, Brca1, and E-cadherin, were downregulated in K5.CtBP1 skin. Surprisingly, K5.CtBP1 pups also exhibited a hair loss phenotype. We found that expression of the Distal-less 3 (Dlx3), a critical regulator of hair follicle differentiation and cycling, was decreased in K5.CtBP1 mice. Molecular studies revealed that CtBP1 directly suppressed Dlx3 transcription. Consistently, K5.CtBP1 mice displayed abnormal hair follicles with decreased expression of Dlx3 downstream targets Gata3, Hoxc13, and hair keratins. In summary, this CtBP1 transgenic model provides in vivo evidence for certain CtBP1 functions predicted from in vitro studies, reveals--to our knowledge--previously unreported functions and transcriptional activities of CtBP1 in the context of epithelial-mesenchymal interplay, and suggests that CtBP1 has a pathogenic role in hair follicle morphogenesis and differentiation.

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Generation of K5.CtBP1 mice and phenotypes. (A) CtBP1 mRNA expression in skin of wildtype mice (WT) and K5.CtBP1 transgenic mice (K1, K2, K3), and acutely wounded WT skin (wound). The mRNA level in WT skin was arbitrarily set as “1”. Error bars indicate s.d. (n=3), significance was determined using Student’s t test. **, p<0.01; *, p<0.05. (B) Hyperplasia/hyperkeratotic gross appearance of a K5.CtBP1 transgenic pup 8 days postpartum, in comparison with WT littermates. (C) Thin and patchy hair in K5.CtBP1 mice 3 weeks postpartum, in comparison with WT littermates. (D) H&E staining of WT and K5.CtBP1 tongue (top panels) and esophagus (bottom panels). Scale bar: 15 μm (top panels) and 40 μm (bottom panels).
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Figure 1: Generation of K5.CtBP1 mice and phenotypes. (A) CtBP1 mRNA expression in skin of wildtype mice (WT) and K5.CtBP1 transgenic mice (K1, K2, K3), and acutely wounded WT skin (wound). The mRNA level in WT skin was arbitrarily set as “1”. Error bars indicate s.d. (n=3), significance was determined using Student’s t test. **, p<0.01; *, p<0.05. (B) Hyperplasia/hyperkeratotic gross appearance of a K5.CtBP1 transgenic pup 8 days postpartum, in comparison with WT littermates. (C) Thin and patchy hair in K5.CtBP1 mice 3 weeks postpartum, in comparison with WT littermates. (D) H&E staining of WT and K5.CtBP1 tongue (top panels) and esophagus (bottom panels). Scale bar: 15 μm (top panels) and 40 μm (bottom panels).

Mentions: In normal mouse skin, CtBP1 is barely detectable. Acute skin wound by punch biopsy induced CtBP1 expression ~6 fold higher than in non-wounded skin (Fig. 1A). To evaluate the role of CtBP1 over-expression in the skin, we generated K5.CtBP1 transgenic mice by inserting human CtBP1 cDNA (99% amino acid homology to mouse CtBP1 protein) into a K5 vector (He et al., 2002). Three K5.CtBP1 transgenic founders (K1, K2, and K3) were generated. Their CtBP1 transgene expression levels were 7–10 fold higher than endogenous CtBP1, but comparable to wounds at the mRNA level (Fig. 1A). Overall, K5.CtBP1 phenotype severity correlated with transgene expression levels, suggesting CtBP1 over-expression causes the phenotype. Results from the representative line K2 were shown in this study. K5.CtBP1 pups were born without gross abnormality (not shown), but began to exhibit thickened skin at 1 week postpartum when wildtype mice developed their first coat of hair and K5.CtBP1 pups had no hair growth (Fig. 1B). After weaning, K5.CtBP1 mice exhibited hair loss, on their dorsal and ventricle sides (Fig. 1C). These transgenic mice died between 3 to 6 weeks of age due to severe hyperplasia in the esophagus (Fig. 1D) and forestomach (not shown) where CtBP1 transgene was also expressed, compromising food intake. Compared to the wildtype control, these K5.CtBP1 mice also displayed abnormal epithelium in their tongues (Fig. 1D).


CtBP1 overexpression in keratinocytes perturbs skin homeostasis.

Deng H, Li F, Li H, Deng Y, Liu J, Wang D, Han G, Wang XJ, Zhang Q - J. Invest. Dermatol. (2013)

Generation of K5.CtBP1 mice and phenotypes. (A) CtBP1 mRNA expression in skin of wildtype mice (WT) and K5.CtBP1 transgenic mice (K1, K2, K3), and acutely wounded WT skin (wound). The mRNA level in WT skin was arbitrarily set as “1”. Error bars indicate s.d. (n=3), significance was determined using Student’s t test. **, p<0.01; *, p<0.05. (B) Hyperplasia/hyperkeratotic gross appearance of a K5.CtBP1 transgenic pup 8 days postpartum, in comparison with WT littermates. (C) Thin and patchy hair in K5.CtBP1 mice 3 weeks postpartum, in comparison with WT littermates. (D) H&E staining of WT and K5.CtBP1 tongue (top panels) and esophagus (bottom panels). Scale bar: 15 μm (top panels) and 40 μm (bottom panels).
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Figure 1: Generation of K5.CtBP1 mice and phenotypes. (A) CtBP1 mRNA expression in skin of wildtype mice (WT) and K5.CtBP1 transgenic mice (K1, K2, K3), and acutely wounded WT skin (wound). The mRNA level in WT skin was arbitrarily set as “1”. Error bars indicate s.d. (n=3), significance was determined using Student’s t test. **, p<0.01; *, p<0.05. (B) Hyperplasia/hyperkeratotic gross appearance of a K5.CtBP1 transgenic pup 8 days postpartum, in comparison with WT littermates. (C) Thin and patchy hair in K5.CtBP1 mice 3 weeks postpartum, in comparison with WT littermates. (D) H&E staining of WT and K5.CtBP1 tongue (top panels) and esophagus (bottom panels). Scale bar: 15 μm (top panels) and 40 μm (bottom panels).
Mentions: In normal mouse skin, CtBP1 is barely detectable. Acute skin wound by punch biopsy induced CtBP1 expression ~6 fold higher than in non-wounded skin (Fig. 1A). To evaluate the role of CtBP1 over-expression in the skin, we generated K5.CtBP1 transgenic mice by inserting human CtBP1 cDNA (99% amino acid homology to mouse CtBP1 protein) into a K5 vector (He et al., 2002). Three K5.CtBP1 transgenic founders (K1, K2, and K3) were generated. Their CtBP1 transgene expression levels were 7–10 fold higher than endogenous CtBP1, but comparable to wounds at the mRNA level (Fig. 1A). Overall, K5.CtBP1 phenotype severity correlated with transgene expression levels, suggesting CtBP1 over-expression causes the phenotype. Results from the representative line K2 were shown in this study. K5.CtBP1 pups were born without gross abnormality (not shown), but began to exhibit thickened skin at 1 week postpartum when wildtype mice developed their first coat of hair and K5.CtBP1 pups had no hair growth (Fig. 1B). After weaning, K5.CtBP1 mice exhibited hair loss, on their dorsal and ventricle sides (Fig. 1C). These transgenic mice died between 3 to 6 weeks of age due to severe hyperplasia in the esophagus (Fig. 1D) and forestomach (not shown) where CtBP1 transgene was also expressed, compromising food intake. Compared to the wildtype control, these K5.CtBP1 mice also displayed abnormal epithelium in their tongues (Fig. 1D).

Bottom Line: Surprisingly, K5.CtBP1 pups also exhibited a hair loss phenotype.Molecular studies revealed that CtBP1 directly suppressed Dlx3 transcription.In summary, this CtBP1 transgenic model provides in vivo evidence for certain CtBP1 functions predicted from in vitro studies, reveals--to our knowledge--previously unreported functions and transcriptional activities of CtBP1 in the context of epithelial-mesenchymal interplay, and suggests that CtBP1 has a pathogenic role in hair follicle morphogenesis and differentiation.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Dermatology, University of Colorado Denver, Aurora, Colorado, USA [2] Department of Pathology, University of Colorado Denver, Aurora, Colorado, USA [3] Department of Dermatology, The Sixth People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China.

ABSTRACT
Carboxyl-terminal-binding protein-1 (CtBP1) is a transcriptional corepressor with multiple in vitro targets, but its in vivo functions are largely unknown. We generated keratinocyte-specific CtBP1 transgenic mice with a keratin-5 promoter (K5.CtBP1) to probe the pathological roles of CtBP1. At transgene expression levels comparable to endogenous CtBP1 in acute skin wounds, the K5.CtBP1 epidermis displayed hyperproliferation, loss of E-cadherin, and failed terminal differentiation. Known CtBP1 target genes associated with these processes, e.g., p21, Brca1, and E-cadherin, were downregulated in K5.CtBP1 skin. Surprisingly, K5.CtBP1 pups also exhibited a hair loss phenotype. We found that expression of the Distal-less 3 (Dlx3), a critical regulator of hair follicle differentiation and cycling, was decreased in K5.CtBP1 mice. Molecular studies revealed that CtBP1 directly suppressed Dlx3 transcription. Consistently, K5.CtBP1 mice displayed abnormal hair follicles with decreased expression of Dlx3 downstream targets Gata3, Hoxc13, and hair keratins. In summary, this CtBP1 transgenic model provides in vivo evidence for certain CtBP1 functions predicted from in vitro studies, reveals--to our knowledge--previously unreported functions and transcriptional activities of CtBP1 in the context of epithelial-mesenchymal interplay, and suggests that CtBP1 has a pathogenic role in hair follicle morphogenesis and differentiation.

Show MeSH
Related in: MedlinePlus