The sterile alpha-motif (SAM) domain of p63 binds in vitro monoasialoganglioside (GM1) micelles (original) (raw)
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Structural basis of p63α SAM domain mutants involved in AEC syndrome
FEBS Journal, 2011
p63 is a member of the p53 tumour suppressor family that includes p73. The p63 gene encodes a protein comprising an N-terminal transactivation domain, a DNA binding domain and an oligomerization domain, but varies in the organization of the C-terminus as a result of complex alternative splicing. p63a contains a C-terminal sterile a motif (SAM) domain that is thought to function as a protein-protein interaction domain. Several missense and heterozygous frame shift mutations, encoded within exon 13 and 14 of the p63 gene, have been identified in the p63a SAM domain in patients suffering from ankyloblepharon-ectodermal dysplasia-clefting syndrome. Here we report the solution and high resolution crystal structures of the p63a SAM domain and investigate the effect of several mutations (L553F ⁄ V, C562G ⁄ W, G569V, Q575L and I576T) on the stability of the domain. The possible effects of other mutations are also discussed.
Journal of Cell Science, 2011
Heterozygous mutations of p63, a key transcription factor in epithelial development, are causative in a variety of human ectodermal dysplasia disorders. Although the mutation spectrum of these disorders displays a striking genotype–phenotype association, the molecular basis for this association is only superficially known. Here, we characterize the transcriptional activity and protein stability of ΔNp63 mutants (that is, mutants of a p63 isoform that lacks the N-terminal transactivation domain) that are found in ectrodactyly–ectodermal dysplasia–cleft syndrome (EEC), ankyloblepharon–ectodermal dysplasia–clefting syndrome (AEC) and nonsyndromic split-hand/split-foot malformation (SHFM). DNA-binding and sterile alpha motif (SAM) domain mutants accumulate in the skin of EEC and AEC syndrome patients, respectively, and show extended half lives in vitro. By contrast, C-terminal mutations found in SHFM patients have half-lives similar to that of the wild-type protein. The increased half-l...
Journal of Cell Science, 2011
Heterozygous mutations of p63, a key transcription factor in epithelial development, are causative in a variety of human ectodermal dysplasia disorders. Although the mutation spectrum of these disorders displays a striking genotype-phenotype association, the molecular basis for this association is only superficially known. Here, we characterize the transcriptional activity and protein stability of Np63 mutants (that is, mutants of a p63 isoform that lacks the N-terminal transactivation domain) that are found in ectrodactylyectodermal dysplasia-cleft syndrome (EEC), ankyloblepharon-ectodermal dysplasia-clefting syndrome (AEC) and nonsyndromic split-hand/split-foot malformation (SHFM). DNA-binding and sterile alpha motif (SAM) domain mutants accumulate in the skin of EEC and AEC syndrome patients, respectively, and show extended half lives in vitro. By contrast, C-terminal mutations found in SHFM patients have half-lives similar to that of the wild-type protein. The increased half-life of EEC and AEC mutant proteins was reverted by overexpression of wild-type Np63. Interestingly, the mutant proteins exhibit normal binding to and degradation by the E3 ubiquitin ligase Itch. Finally, EEC and AEC mutant proteins have reduced transcriptional activity on several skin-specific gene promoters, whereas SHFM mutant proteins are transcriptionally active. Our results, therefore, provide evidence for a regulatory feedback mechanism for p63 that links transcriptional activity to regulation of protein homeostasis by an unknown mechanism. Disruption of this regulatory mechanism might contribute to the pathology of p63-related developmental disorders.
Cellular and Molecular Life Sciences, 2008
The epidermis, the outer layer of the skin composed of keratinocytes, is a stratified epithelium that functions as a barrier to protect the organism from dehydration and external insults. The epidermis develops following the action of the transcription factor p63, a member of the p53 family of transcription factors. The Trp63 gene contains two promoters, driving the production of distinct proteins, one with an N-terminal transactivation domain (TAp63) and one without (DeltaNp63), although their relative contribution to epidermal development is not clearly established. Trp63 mutations are involved in the pathogenesis of several human diseases, phenotypically characterized by ectodermal dysplasia. In this review we summarise the current advances that have been made in understanding the role of p63 in epidermal morphogenesis.
Identification of New p63 Targets in Human Keratinocytes
Cell Cycle, 2006
p63 is a transcription factor involved in the development of ectodermal tissues, including limb, skin and, in general, multilayered epithelia. We identified both activated and repressed genes in human keratinocytes via gene expression profiling of p63depleted cells and validated 21 new primary targets by RT-PCR and ChIP location analysis. The p63 isoforms differentially activate or repress selected promoters. ChIPs in primary keratinocytes indicate that p63 targets are generally shared with p53, but some are p63-specific. Several growth suppressors are among repressed genes. The newly identified genes belong to pathways of growth and differentiation and are regulated in HaCaT differentiation and in stratification of human skin.
A heterozygous mutation in the SAM domain of p63 underlies a mild form of ectodermal dysplasia
Journal of dermatological science, 2018
In conclusion, we demonstrate that an inhibitor of Hsp90 could enhance the apoptotic effect of hyperthermic conditions on melanoma cells. The Hsp90 inhibitor 17-DMAG inhibited the growth and enhanced the apoptosis of SK-MEL-2 melanoma cells through degradation of Hsp90 via the AKT and p38 MAPK pathways. Our results suggest that the Hsp 90 inhibitor under hyperthermic state could be an adjuvant treatment for melanoma.
Transcriptional control orchestrated by p63 in skin disease
2020
The transcription factor p63………………………………………………….11 Part I: p63 in skin cancers Skin cancers………………………………………………………………….16 3.1 Cutaneous squamous cell carcinoma (cSCC)……..………………………...17 3.2 p63 in cancer…………………………………………………………………..19 Biology of Poly (ADP-Ribose) Polymerases (PARPs)…………….………..21 4.1 Enzymology of PARPs………………………………………………………...22 4.2 PARP1 and poly-(ADP)-ribosylation in DNA repair………………...………..23 4.3 PARP1 involvement in chromatin structure and gene transcription control.….25 Aim I……………………………………………………………………………. 29 Results……………………………………………………………………...…….30 P63 is overexpressed in cutaneous squamous cell carcinoma……………….30 P63 gene regulation in cSCC………………………………….….………….32 P63 sustain cSCC cell proliferation………………………………..………...33 PARP1 is a novel interactor of p63………………………………….……….35 PARP1 is overexpressed in cSCC…………………………………...……….40 P63 and PARP1 regulates genes involved in cell proliferation……………....42 PARP1 is involved in the regulation of cancer cell growth………………….47
Identification of a Sam68 Ribonucleoprotein Complex Regulated by Epidermal Growth Factor
Journal of Biological Chemistry, 2009
Sam68, Src associated in mitosis of 68 kDa, is a known RNAbinding protein and a signaling adaptor protein for tyrosine kinases. However, the proteins associated with Sam68 and the existence of a Sam68 complex, its mass, and regulation are, however, unknown. Herein we identify a large Sam68 complex with a mass >1 MDa in HeLa cells that is composed of ϳ40 proteins using an immunoprecipitation followed by a mass spectrometry approach. Many of the proteins identified are RNA-binding proteins and are known components of a previously identified structure termed the spreading initiation center. The large Sam68 complex is a ribonucleoprotein complex, as treatment with RNases caused a shift in the molecular mass of the complex to 200 -450 kDa. Moreover, treatment of HeLa cells with phorbol 12-myristate 13-acetate or epidermal growth factor induced the disassociation of Sam68 from the large complex and the appearance of Sam68 within the smaller complex. Actually, in certain cell lines such as breast cancer cell lines MCF-7 and BT-20, Sam68 exists in equilibrium between a large and a small complex. The appearance of the small Sam68 complex in cells correlates with the ability of Sam68 to promote the alternative splicing of CD44 and cell migration. Our findings show that Sam68 exists in equilibrium in transformed cells between two complexes and that extracellular signals, such as epidermal growth factor stimulation, promote alternative splicing by modulating the composition of the Sam68 complex.