Project description:Disrupted skin barrier due to altered keratinocyte differentiation is common in pathologic conditions such as atopic dermatitis, ichthyosis and psoriasis. However, the molecular cascades governing keratinocyte terminal differentiation are still poorly understood. We have previously demostrated that a dominante mutation in ZNF750 leads to a clinical phenotype that reminiscent of psoriasis and seborrehic dermatitis. We defined ZNF750 as a nuclear effector that is atrongly activated in and essiential for keratinocyte terminal differentiation. ZNF750 knockdown in HaCaT keratinocytes markedly reduced the expression of epidermal late differentiation markers, including gene subsets of epidermal differentiation complex and skin barrier formation such as FLG, LOR, SPINK5, ALOX12B and DSG1, known to be mutated in various human skin diseases. Furthermore, ZNF750 over-expression in undifferentiated cells induced terminal differentiation genes. Thus, ZNF750 is a regulator of keratinocyte terminal differnetiation, and with its downstream targets can serve in future elucidation of therapeutics for common disease of skin barrier Gene expression analysis: To determine the differentaition signature for HaCaT keratinocytes, with ZNF750 gene silencing, total RNA was isolated in biologic triplicates from cells induced to differentiate for twelve days and hybridized to Affymerix Human Gene 1.0 ST arrays.
Project description:Disrupted skin barrier due to altered keratinocyte differentiation is common in pathologic conditions such as atopic dermatitis, ichthyosis and psoriasis. However, the molecular cascades governing keratinocyte terminal differentiation are still poorly understood. We have previously demonstrated that a dominant mutation in ZNF750 leads to a clinical phenotype that reminiscent of psoriasis and seborrheic dermatitis. We defined ZNF750 as a nuclear effector that is strongly activated in and essential for keratinocyte terminal differentiation. ZNF750 knockdown in HaCaT keratinocytes markedly reduced the expression of epidermal late differentiation markers, including gene subsets of epidermal differentiation complex and skin barrier formation such as FLG, LOR, SPINK5, ALOX12B and DSG1, known to be mutated in various human skin diseases. Furthermore, ZNF750 over-expression in undifferentiated cells induced terminal differentiation genes. Thus, ZNF750 is a regulator of keratinocyte terminal differentiation, and with its downstream targets can serve in future elucidation of therapeutics for common disease of skin barrier
Project description:Disrupted differentiation is a hallmark of numerous diseases, which in epidermis alone impact >25% of the population. In a search for dominant mediators of differentiation, we defined a requirement for the ZNF750 nuclear protein in terminal epidermal differentiation. ZNF750 controlled genes mutated in numerous human skin diseases, including FLG, LOR, LCE3B, ALOXE3, and SPINK5. ZNF750 potently induced progenitor differentiation via an evolutionarily conserved C2H2 zinc finger motif. The epidermal master regulator, p63, bound the ZNF750 promoter and was necessary for its induction. ZNF750 restored differentiation to p63-deficient tissue, suggesting it acts downstream of p63. A search for functionally important ZNF750 targets via analysis of ZNF750-regulated genes identified KLF4, a transcription factor that activates late epidermal differentiation genes. ZNF750 binds the Klf4 promoter and controls its expression. ZNF750 thus provides a direct link between a tissue-specifying factor, p63, and an effector of terminal differentiation, Klf4, and represents a potential future target for disorders of this process.
Project description:Disrupted differentiation is a hallmark of numerous diseases, which in epidermis alone impact >25% of the population. In a search for dominant mediators of differentiation, we defined a requirement for the ZNF750 nuclear protein in terminal epidermal differentiation. ZNF750 controlled genes mutated in numerous human skin diseases, including FLG, LOR, LCE3B, ALOXE3, and SPINK5. ZNF750 potently induced progenitor differentiation via an evolutionarily conserved C2H2 zinc finger motif. The epidermal master regulator, p63, bound the ZNF750 promoter and was necessary for its induction. ZNF750 restored differentiation to p63-deficient tissue, suggesting it acts downstream of p63. A search for functionally important ZNF750 targets via analysis of ZNF750-regulated genes identified KLF4, a transcription factor that activates late epidermal differentiation genes. ZNF750 binds the Klf4 promoter and controls its expression. ZNF750 thus provides a direct link between a tissue-specifying factor, p63, and an effector of terminal differentiation, Klf4, and represents a potential future target for disorders of this process. Gene expression analysis: To establish a differentiation signature for primary human keratinocytes, with ZNF750-depleted, and Klf4-depleted, total RNA was isolated in biologic duplicate from cells in different conditions and hybridized to Affymetrix HG-U133 2.0 Plus arrays.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:The skin epidermis is a constantly renewing stratified epithelial tissue that provides essential protective barrier functions. The major barrier is at the outermost layers of the epidermis, formed by terminally differentiated keratinocytes reinforced by proteins and lipids of their cornified envelope (CE), and disruptions to this process characterizes common skin disorders. ZNF750 is an epithelial transcription factor essential for in vitro keratinocyte differentiation, whose autosomal dominant mutation in humans causes psoriasis-like skin disease. Here, we report epidermal-specific Znf750 conditional knockout mouse model utilized to uncover the role of Znf750 in epidermal development. We show that deletion of Znf750 in the developing skin does not block epidermal differentiation, suggesting in vivo compensatory feedback mechanisms, yet results in impaired barrier function and perinatal lethality. Molecular dissection uncovered ultrastructural defects in the differentiated layers of the epidermis, accompanied by alterations in the expression of ZNF750-dependent genes encoding for key proteins and lipids involved in CE formation, including gene subsets known to be mutated in skin disease with impaired barrier function.
Project description:As the evolution of miRNA genes has been found to be one of the important factors in formation of the modern type of man, we performed a comparative analysis of the evolution of miRNA genes in two archaic hominines, Homo sapiens neanderthalensis and Homo sapiens denisova, and elucidated the expression of their target mRNAs in bain.A comparative analysis of the genomes of primates, including species in the genus Homo, identified a group of miRNA genes having fixed substitutions with important implications for the evolution of Homo sapiens neanderthalensis and Homo sapiens denisova. The mRNAs targeted by miRNAs with mutations specific for Homo sapiens denisova exhibited enhanced expression during postnatal brain development in modern humans. By contrast, the expression of mRNAs targeted by miRNAs bearing variations specific for Homo sapiens neanderthalensis was shown to be enhanced in prenatal brain development.Our results highlight the importance of changes in miRNA gene sequences in the course of Homo sapiens denisova and Homo sapiens neanderthalensis evolution. The genetic alterations of miRNAs regulating the spatiotemporal expression of multiple genes in the prenatal and postnatal brain may contribute to the progressive evolution of brain function, which is consistent with the observations of fine technical and typological properties of tools and decorative items reported from archaeological Denisovan sites. The data also suggest that differential spatial-temporal regulation of gene products promoted by the subspecies-specific mutations in the miRNA genes might have occurred in the brains of Homo sapiens denisova and Homo sapiens neanderthalensis, potentially contributing to the cultural differences between these two archaic hominines.