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Activation of TLR3 in keratinocytes increases expression of genes involved in formation of the epidermis, lipid accumulation, and epidermal organelles.

Borkowski AW, Park K, Uchida Y, Gallo RL - J. Invest. Dermatol. (2013)

Bottom Line: Injury to the skin, and the subsequent release of noncoding double-stranded RNA (dsRNA) from necrotic keratinocytes, has been identified as an endogenous activator of Toll-like receptor 3 (TLR3).Additionally, treatment with dsRNA resulted in increases in sphingomyelin and morphologic changes including increased epidermal lipid staining by Oil Red O and TLR3-dependent increases in lamellar bodies and keratohyalin granules.These observations show that dsRNA can stimulate some events in keratinocytes that are important for skin barrier repair and maintenance.

View Article: PubMed Central - PubMed

Affiliation: Division of Dermatology, University of California, San Diego, San Diego, California 92093-0869, USA.

ABSTRACT
Injury to the skin, and the subsequent release of noncoding double-stranded RNA (dsRNA) from necrotic keratinocytes, has been identified as an endogenous activator of Toll-like receptor 3 (TLR3). As changes in keratinocyte growth and differentiation follow injury, we hypothesized that TLR3 might trigger some elements of the barrier repair program in keratinocytes. dsRNA was observed to induce TLR3-dependent increases in human keratinocyte mRNA abundance for ABCA12 (ATP-binding cassette, sub-family A, member 12), glucocerebrosidase, acid sphingomyelinase, and transglutaminase 1. Additionally, treatment with dsRNA resulted in increases in sphingomyelin and morphologic changes including increased epidermal lipid staining by Oil Red O and TLR3-dependent increases in lamellar bodies and keratohyalin granules. These observations show that dsRNA can stimulate some events in keratinocytes that are important for skin barrier repair and maintenance.

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Gene expression profiling of NHEK identifies upregulation of genes involved in lipid biosynthesis, metabolism, and transporter pathways following treatment with dsRNA(a) Significantly changed genes analyzed using DAVID to identify significant pathways (EASE = 1.0). (b) Genes involved in barrier formation with a significant change as identified by SAM
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Figure 1: Gene expression profiling of NHEK identifies upregulation of genes involved in lipid biosynthesis, metabolism, and transporter pathways following treatment with dsRNA(a) Significantly changed genes analyzed using DAVID to identify significant pathways (EASE = 1.0). (b) Genes involved in barrier formation with a significant change as identified by SAM

Mentions: To identify gene expression pathways in addition to the known inflammatory response associated with TLR3 activation of keratinocytes, we examined the transcriptome of NHEK 24 hours after exposure to the dsRNA Poly(I:C). In response to Poly (I:C), a total of 5542 differentially regulated genes changed by at least 2-fold (2773 upregulated and 2769 downregulated; SAM: triplicate; FDR < 0.01%; delta value = 1.397) (Supplemental Figure S1a). These genes were further analyzed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) (Huang et al., 2009; Huang et al., 2009). This analysis suggested Poly(I:C) affected a number of pathways involved in lipid metabolism and transport. Specifically, changes were observed in the expression of genes in glycosphingolipid biosynthesis, ABC transporters, sphingolipid metabolism, and other lipid biosynthesis/metabolism and inflammatory pathways (Figure 1a). Several specific genes identified by this approach are known to play a role in maintaining or forming the skin barrier, such as: ABCA12 (3.74-fold), GBA (2.02-fold), SMPD1 (2.04-fold), TGM1 (2.40-fold), as well as tumor necrosis factor (TNF) (5.31-fold), interleukin 6 (IL-6) (27.31-fold), and TLR3 (14.58-fold). Involucrin (IVL), loricrin (LOR), keratin 1 (KRT1), keratin 14 (KRT14) and filaggrin (FLG), markers of epidermal differentiation, were not changed significantly (Figure 1b). The results of the microarray showed that genes involved in synthesis of ceramides (UGCG, SPTLC1, SPTLC2), free fatty acids (ACACA and FASN) and cholesterol (FDFT1, HMCCR, and HMGSC1) were not significantly altered other than acetyl CoA carboxylase (ACACA) (0.33-fold).


Activation of TLR3 in keratinocytes increases expression of genes involved in formation of the epidermis, lipid accumulation, and epidermal organelles.

Borkowski AW, Park K, Uchida Y, Gallo RL - J. Invest. Dermatol. (2013)

Gene expression profiling of NHEK identifies upregulation of genes involved in lipid biosynthesis, metabolism, and transporter pathways following treatment with dsRNA(a) Significantly changed genes analyzed using DAVID to identify significant pathways (EASE = 1.0). (b) Genes involved in barrier formation with a significant change as identified by SAM
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3686920&req=5

Figure 1: Gene expression profiling of NHEK identifies upregulation of genes involved in lipid biosynthesis, metabolism, and transporter pathways following treatment with dsRNA(a) Significantly changed genes analyzed using DAVID to identify significant pathways (EASE = 1.0). (b) Genes involved in barrier formation with a significant change as identified by SAM
Mentions: To identify gene expression pathways in addition to the known inflammatory response associated with TLR3 activation of keratinocytes, we examined the transcriptome of NHEK 24 hours after exposure to the dsRNA Poly(I:C). In response to Poly (I:C), a total of 5542 differentially regulated genes changed by at least 2-fold (2773 upregulated and 2769 downregulated; SAM: triplicate; FDR < 0.01%; delta value = 1.397) (Supplemental Figure S1a). These genes were further analyzed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) (Huang et al., 2009; Huang et al., 2009). This analysis suggested Poly(I:C) affected a number of pathways involved in lipid metabolism and transport. Specifically, changes were observed in the expression of genes in glycosphingolipid biosynthesis, ABC transporters, sphingolipid metabolism, and other lipid biosynthesis/metabolism and inflammatory pathways (Figure 1a). Several specific genes identified by this approach are known to play a role in maintaining or forming the skin barrier, such as: ABCA12 (3.74-fold), GBA (2.02-fold), SMPD1 (2.04-fold), TGM1 (2.40-fold), as well as tumor necrosis factor (TNF) (5.31-fold), interleukin 6 (IL-6) (27.31-fold), and TLR3 (14.58-fold). Involucrin (IVL), loricrin (LOR), keratin 1 (KRT1), keratin 14 (KRT14) and filaggrin (FLG), markers of epidermal differentiation, were not changed significantly (Figure 1b). The results of the microarray showed that genes involved in synthesis of ceramides (UGCG, SPTLC1, SPTLC2), free fatty acids (ACACA and FASN) and cholesterol (FDFT1, HMCCR, and HMGSC1) were not significantly altered other than acetyl CoA carboxylase (ACACA) (0.33-fold).

Bottom Line: Injury to the skin, and the subsequent release of noncoding double-stranded RNA (dsRNA) from necrotic keratinocytes, has been identified as an endogenous activator of Toll-like receptor 3 (TLR3).Additionally, treatment with dsRNA resulted in increases in sphingomyelin and morphologic changes including increased epidermal lipid staining by Oil Red O and TLR3-dependent increases in lamellar bodies and keratohyalin granules.These observations show that dsRNA can stimulate some events in keratinocytes that are important for skin barrier repair and maintenance.

View Article: PubMed Central - PubMed

Affiliation: Division of Dermatology, University of California, San Diego, San Diego, California 92093-0869, USA.

ABSTRACT
Injury to the skin, and the subsequent release of noncoding double-stranded RNA (dsRNA) from necrotic keratinocytes, has been identified as an endogenous activator of Toll-like receptor 3 (TLR3). As changes in keratinocyte growth and differentiation follow injury, we hypothesized that TLR3 might trigger some elements of the barrier repair program in keratinocytes. dsRNA was observed to induce TLR3-dependent increases in human keratinocyte mRNA abundance for ABCA12 (ATP-binding cassette, sub-family A, member 12), glucocerebrosidase, acid sphingomyelinase, and transglutaminase 1. Additionally, treatment with dsRNA resulted in increases in sphingomyelin and morphologic changes including increased epidermal lipid staining by Oil Red O and TLR3-dependent increases in lamellar bodies and keratohyalin granules. These observations show that dsRNA can stimulate some events in keratinocytes that are important for skin barrier repair and maintenance.

Show MeSH
Related in: MedlinePlus