25 research outputs found
Contribution of the different modules in the utrophin carboxy-terminal region to the formation and regulation of the DAP complex
No full textIntegration of Notch1 and calcineurin/NFAT signaling pathway in keratinocyte growth and differentiation control.
No full textNoThe Notch and Calcineurin/NFAT pathways have both been implicated in control of keratinocyte differentiation. Induction of the p21WAF1/Cip1 gene by Notch 1 activation in differentiating keratinocytes is associated with direct targeting of the RBP-J¿ protein to the p21 promoter. We show here that Notch 1 activation functions also through a second Calcineurin-dependent mechanism acting on the p21 TATA box-proximal region. Increased Calcineurin/NFAT activity by Notch signaling involves downregulation of Calcipressin, an endogenous Calcineurin inhibitor, through a HES-1-dependent mechanism. Besides control of the p21 gene, Calcineurin contributes significantly to the transcriptional response of keratinocytes to Notch 1 activation, both in vitro and in vivo. In fact, deletion of the Calcineurin B1 gene in the skin results in a cyclic alopecia phenotype, associated with altered expression of Notch-responsive genes involved in hair follicle structure and/or adhesion to the surrounding mesenchyme. Thus, an important interconnection exists between Notch 1 and Calcineurin-NFAT pathways in keratinocyte growth/differentiation control
High commitment of embryonic keratinocytes to terminal differentiation through a Notch1-caspase 3 regulatory mechanism.
No full textAbstractEmbryonic cells are expected to possess high growth/differentiation potential, required for organ morphogenesis and expansion during development. However, little is known about the intrinsic properties of embryonic epithelial cells due to difficulties in their isolation and cultivation. We report here that pure keratinocyte populations from E15.5 mouse embryos commit irreversibly to differentiation much earlier than newborn cells. Notch signaling, which promotes keratinocyte differentiation, is upregulated in embryonic keratinocyte and epidermis, and elevated caspase 3 expression, which we identify as a transcriptional Notch1 target, accounts in part for the high commitment of embryonic keratinocytes to terminal differentiation. In vivo, lack of caspase 3 results in increased proliferation and decreased differentiation of interfollicular embryonic keratinocytes, together with decreased activation of PKC-δ, a caspase 3 substrate which functions as a positive regulator of keratinocyte differentiation. Thus, a Notch1-caspase 3 regulatory mechanism underlies the intrinsically high commitment of embryonic keratinocytes to terminal differentiation
Contribution of the different modules in the utrophin carboxy-terminal region to the formation and regulation of the DAP complex
No full textAbstractThe carboxy-terminal region of utrophin, like the homologous proteins dystrophin, Drp2 and dystrobrevins, contains structural domains frequently involved in protein–protein interaction. These domains (WW, EF hands, ZZ and H1–H2) mediate recognition and binding to a multicomponent complex of proteins, also known as dystrophin-associated proteins (DAPs) for their association with dystrophin, the product of the gene, mutated in Duchenne muscular dystrophy. We have exploited phage display and in vitro binding assays to study the recognition specificity of the different domains of the utrophin carboxy-terminus. We found that none of the carboxy-terminal domains of utrophin, when isolated from its structural context, selects specific ligand peptides from a phage-displayed peptide library. By contrast, panning with an extended region containing the WW, EF hands, and ZZ domain defines the consensus binding motif, PPxY which is also found in β-dystroglycan, a component of the DAP complex that interacts with utrophin in several tissues. WW-mediated binding to PPxY peptides and to β-dystroglycan requires the presence of the EF hands and ZZ domain. When the ZZ domain is either deleted or engaged in binding to calmodulin, the utrophin β-dystroglycan complex cannot be formed. These findings suggest a potential regulatory mechanism by means of which the attachment of utrophin to the DAP complex can be modulated by the Ca2+-dependent binding of calmodulin. The remaining two motifs found in the carboxy-terminus (H1–H2) mediate the formation of utrophin–dystrobrevin hybrids but do not select ligands in a repertoire of random nonapeptides
TOMMASI DI VIGNANO, Alessandro: La permeabilità intersistemática tra ordinamenti di Stati diversi (lntroduzione allo studio del Diritto internazionale privato). Herbita Editrice. Palermo, 1975 (302 págs.) [RECENSIÓN]
No full textIdentification of epidermal Pdx1 expression discloses different roles of Notch1 and Notch2 in murine KrasG12D-induced skin carcinogenesis in vivo
No full textBackground
The Ras and Notch signaling pathways are frequently activated during development to control many diverse cellular processes and are often dysregulated during tumorigenesis. To study the role of Notch and oncogenic Kras signaling in a progenitor cell population, Pdx1-Cre mice were utilized to generate conditional oncogenic KrasG12D mice with ablation of Notch1 and/or Notch2.
Methodology/Principal Findings
Surprisingly, mice with activated KrasG12D and Notch1 but not Notch2 ablation developed skin papillomas progressing to squamous cell carcinoma providing evidence for Pdx1 expression in the skin. Immunostaining and lineage tracing experiments indicate that PDX1 is present predominantly in the suprabasal layers of the epidermis and rarely in the basal layer. Further analysis of keratinocytes in vitro revealed differentiation-dependent expression of PDX1 in terminally differentiated keratinocytes. PDX1 expression was also increased during wound healing. Further analysis revealed that loss of Notch1 but not Notch2 is critical for skin tumor development. Reasons for this include distinct Notch expression with Notch1 in all layers and Notch2 in the suprabasal layer as well as distinctive p21 and β-catenin signaling inhibition capabilities.
Conclusions/Significance
Our results provide strong evidence for epidermal expression of Pdx1 as of yet not identified function. In addition, this finding may be relevant for research using Pdx1-Cre transgenic strains. Additionally, our study confirms distinctive expression and functions of Notch1 and Notch2 in the skin supporting the importance of careful dissection of the contribution of individual Notch receptors
Bone morphogenetic protein signaling regulates size of hair follicles and modulates the expression of cell cycle-associated genes.
No full textNoBone morphogenetic protein (BMP) signaling is involved in the regulation of a large variety of developmental programs, including those controlling organ sizes. Here, we show that transgenic (TG) mice overexpressing the BMP antagonist noggin (promoter, K5) are characterized by a marked increase in size of anagen hair follicles (HFs) and by the replacement of zig-zag and auchen hairs by awl-like hairs, compared with the age-matched WT controls. Markedly enlarged anagen HFs of TG mice show increased proliferation in the matrix and an increased number of hair cortex and medulla cells compared with WT HFs. Microarray and real-time PCR analyses of the laser-captured hair matrix cells show a strong decrease in expression of Cdk inhibitor p27(Kip1) and increased expression of selected cyclins in TG vs. WT mice. Similar to TG mice, p27(Kip1) knockout mice also show an increased size of anagen HFs associated with increased cell proliferation in the hair bulb. Primary epidermal keratinocytes (KC) from TG mice exhibit significantly increased proliferation and decreased p27(Kip1) expression, compared with WT KC. Alternatively, activation of BMP signaling in HaCaT KC induces growth arrest, stimulates p27(Kip1) expression, and positively regulates p27(Kip1) promoter activity, thus further supporting a role of p27(Kip1) in mediating the effects of BMP signaling on HF size. These data suggest that BMP signaling plays an important role in regulating cell proliferation and controls the size of anagen HFs by modulating the expression of cell-cycle-associated genes in hair matrix KC
The FoxO3a gene is a key negative target of canonical Notch signalling in the keratinocyte UVB response
No full text
