Project description:Human mesenchymal stem cells (hMSC) have an extensive potential for clinical applications in cell therapy. However, very little is known of the specific molecular regulatory mechanisms that control the therapeutical properties of these cells. We aimed to identify microRNAs (miRNAs) that could be involved in controlling the transition between the self-renewing (undifferentiated) and the reparative (differentiated) phenotypes of hMSCs. MicroRNA microarrays were used to identify miRNAs that are upregulated in undifferentiated hMSCs. For that, we compared the miRNA expression profiles of undifferentiated bone marrow-derived hMSCs with the same primary cell lines after 9 days of in vitro adipogenic or osteogenic induction. We also compared the miRNA expression profiles of undifferentiated hMSCs with skin fibroblasts (a mesenchymal cell lineage with a more restricted differentiation potential). These experiments allowed us to identify miR-335 as the only miRNA downregulated upon MSC differentiation as well as in MSCs in comparison with skin fibroblasts. Gene expression microarrays were used to identify genes that are downregulated in hMSCs overexpressing miR-335. We compared the miRNA expression profiles of hMSCs transduced with a lentiviral vector encoding miR-335 with MSCs transduced with a control lentiviral vector. Our results suggest miR-335 downregulation could be a critical trigger for the initiation of MSCs activities involved in tissue repair and remodelling, including cell proliferation, migration and differentiation.
Project description:Human mesenchymal stem cells (hMSC) have an extensive potential for clinical applications in cell therapy. However, very little is known of the specific molecular regulatory mechanisms that control the therapeutical properties of these cells. We aimed to identify microRNAs (miRNAs) that could be involved in controlling the transition between the self-renewing (undifferentiated) and the reparative (differentiated) phenotypes of hMSCs. MicroRNA microarrays were used to identify miRNAs that are upregulated in undifferentiated hMSCs. For that, we compared the miRNA expression profiles of undifferentiated bone marrow-derived hMSCs with the same primary cell lines after 9 days of in vitro adipogenic or osteogenic induction. We also compared the miRNA expression profiles of undifferentiated hMSCs with skin fibroblasts (a mesenchymal cell lineage with a more restricted differentiation potential). These experiments allowed us to identify miR-335 as the only miRNA downregulated upon MSC differentiation as well as in MSCs in comparison with skin fibroblasts. Gene expression microarrays were used to identify genes that are downregulated in hMSCs overexpressing miR-335. We compared the miRNA expression profiles of hMSCs transduced with a lentiviral vector encoding miR-335 with MSCs transduced with a control lentiviral vector. Our results suggest miR-335 downregulation could be one of the triggers for the initiation of MSCs activities involved in tissue repair and remodelling, including cell migration and differentiation. We compared the miRNA expression profiles of undifferentiated bone marrow-derived hMSCs with the same primary cell lines after 9 days of adipogenic or osteogenic induction, as well as with skin fibroblasts. A total of four independent samples were used for each condition. For the adipogenic/osteogenic vs. undifferentiated MSC comparison, the RNA samples were pooled (two independent samples/pool) before labeling. We also compared the miRNA expression profiles of hMSCs transduced with the lentiviral vector pLV-EmGFP-MIRN335 with MSCs transduced with the control vector pLV-EmGFP-Mock. For the gene expression microarrays, a total of three independent samples were used for each condition.
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:Notch signaling promotes commitment of keratinocytes to differentiation and suppresses tumorigenesis. p63, a p53 family member, has been implicated in establishment of the keratinocyte cell fate and/or maintenance of epithelial self-renewal. Here we show that p63 expression is suppressed by Notch1 activation in both mouse and human keratinocytes through a mechanism independent of cell cycle withdrawal and requiring down-modulation of selected interferon-responsive genes, including IRF7 and/or IRF3. In turn, elevated p63 expression counteracts the ability of Notch1 to restrict growth and promote differentiation. p63 functions as a selective modulator of Notch1-dependent transcription and function, with the Hes-1 gene as one of its direct negative targets. Thus, a complex cross-talk between Notch and p63 is involved in the balance between keratinocyte self-renewal and differentiation. Keywords: Notch1, p63, keratinocyte differentiation, gene expression profiling
Project description:Development of epidermis includes a complicated program of keratinocyte differentiation. Here we study a new membrane LIM-domain containing Zn-finger protein ZNF185 which is expressed in upper layers of human skin and is up-regulated during keratinocyte differentiation in vitro. Interestingly, depletion of ZNF185 causes delay of keratinocyte differentiation with decreased levels of FLG, LOR, LCEs expression.
Project description:Skin toxicity is a frequently observed side effect in the era of "molecularly targeted therapies". Skin toxicity following administration of protein kinase inhibitors such as sorafenib, regorafenib, lapatinib, sunitinib, and others can be debilitating to the patient, resulting in dose reduction and discontinuation of treatment. The mechanisms of skin toxicity induced by targeted chemotherapy, such as sorafenib or regorafenib, are poorly understood. Further research is warranted to better understand the pathophysiology of drug-related skin toxicity in this setting and develop correction strategies. This study tests the hypothesis that sorafenib and regorafenib interfere with p63 expression and keratinocyte differentiation and skin remodeling.
Eligible study participants will be evaluated clinically for evidence of skin toxicity during their visits to the outpatient Oncology clinics. Study participants will undergo skin biopsies before sorafenib or regorafenib treatment is initiated and once rash develops or 12 weeks into treatment with sorafenib or regorafenib. Skin biopsies will be performed in Oncology clinics by the study investigators and clinic support staff.
Study participants will undergo both skin biopsies regardless of whether they develop a rash. In patients who develop a rash the most representative lesion will be biopsied. A normal appearing area of skin will be biopsied in participants who do not develop a rash.