Keratinocyte-specific Knockout Research Articles

Liraglutide Promotes Diabetic Wound Healing via Myo1c/Dock5.

Non-healing diabetic wounds and ulcer complications, with persistent cell dysfunction and obstructed cellular processes, are leading causes of disability and death in patients with diabetes. Currently, there is a lack of guideline-recommended hypoglycemic drugs in clinical practice, likely due to limited research and unclear mechanisms. In this study, it is demonstrated that liraglutide significantly accelerates wound closure in diabetic mouse models (db/db mice and streptozotocin-induced mice) by improving re-epithelialization, collagen deposition, and extracellular matrix remodeling, and enhancing the proliferation, migration, and adhesion functions of keratinocytes. However, these effects of improved healing by liraglutide are abrogated in dedicator of cytokinesis 5 (Dock5) keratinocyte-specific knockout mice. Mechanistically, liraglutide induces cellular function through stabilization of unconventional myosin 1c (Myo1c). Liraglutide directly binds to Myo1c at arginine 93, enhancing the Myo1c/Dock5 interaction by targeting Dock5 promoter and thus promoting the proliferation, migration, and adhesion of keratinocytes. Therefore, this study provides insights into liraglutide biology and suggests it may be an effective treatment for diabetic patients with wound-healing pathologies.

Keratinocyte and myeloid MCPIP1 have distinct roles in maintaining skin homeostasis

The skin is a complex organ, and the intricate network between keratinocytes and immune cells is critical for ensuring skin function. Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) is a ribonuclease that functions as a key negative modulator of inflammation. We previously reported that conditional deletion of MCPIP1 in keratinocytes (Mcpip1EKO) impairs skin integrity in adult mice. A similar phenotype was observed following the depletion of MCPIP1 in the myeloid compartment (Mcpip1MKO).The aim of this study was to develop a keratinocyte and myeloid double-MCPIP1 knockout mouse model to clarify the specific roles of myeloid and epidermal MCPIP1 in skin biology.Histological analyses indicated that the skin morphology changed after depletion of MCPIP1 in cells of myeloid origin as well as in keratinocytes. The thicknesses of the epidermal and subcutaneous fat layers increased in the mice with a loss of epidermal MCPIP1, whereas the loss of myeloid MCPIP1 had the opposite effect. In addition, both types of mice showed opposite responses to stimulation with 12-O-tetradecanoylphorbol-13-acetate. Transcriptomic profiling of whole-skin lysates revealed some common target transcripts in all the knockout mice. Further analyses revealed that distinct pathways are modulated following the loss of epidermal or myeloid MCPIP1. The skin morphology and inflammatory phenotype of keratinocyte and myeloid double-MCPIP1 knockout mice resembled those of mice with only keratinocyte-specific knockout of MCPIP1.Overall, myeloid and epidermal MCPIP1 play important but distinct roles in the modulation of skin-related processes.

IL-38 Aggravates Atopic Dermatitis via Facilitating Migration of Langerhans cells.

Atopic dermatitis (AD) is a common inflammation skin disease that involves dysregulated interplay between immune cells and keratinocytes. Interleukin-38 (IL-38), a poorly characterized IL-1 family cytokine, its role and mechanism in the pathogenesis of AD is elusive. Here, we show that IL-38 is mainly secreted by epidermal keratinocytes and highly expressed in the skin and downregulated in AD lesions. We generated IL-38 keratinocyte-specific knockout mice (K14Cre/+-IL-38f/f ) and induced AD models by 2,4-dinitrofluorobenzene (DNFB). Unexpectedly, after treatment with DNFB, K14Cre/+-IL-38f/f mice were less susceptible to cutaneous inflammation of AD. Moreover, keratinocyte-specific deletion of IL-38 suppressed the migration of Langerhans cells (LCs) into lymph nodes which results in disturbed differentiation of CD4+T cells and decreased the infiltration of immune cells into AD lesions. LCs are a type of dendritic cell that reside specifically in the epidermis and regulate immune responses. We developed LC-like cells in vitro from mouse bone marrow (BM) and treated with recombined IL-38. The results show that IL-38 depended on IL-36R, activated the phosphorylated expression of IRAK4 and NF-κB P65 and upregulated the expression of CCR7 to promoting the migration of LCs, nevertheless, the upregulation disappeared with the addition of IL-36 receptor antagonist (IL-36RA), IRAK4 or NF-κB P65 inhibitor. Furthermore, after treatment with IRAK4 inhibitors, the experimental AD phenotypes were alleviated and so IRAK4 is considered a promising target for the treatment of inflammatory diseases. Overall, our findings indicated a potential pathway that IL-38 depends on IL-36R, leading to LCs migration to promote AD by upregulating CCR7 via IRAK4/NF-κB and implied the prevention and treatment of AD, supporting potential clinical utilization of IRAK4 inhibitors in AD treatment.

Discovery and Potential Functional Characterization of Long Noncoding RNAs Associated with Familial Acne Inversa with NCSTN Mutation

Background: Long noncoding RNAs (lncRNAs) are associated with many dermatologic diseases. However, little is known about the regulatory function of lncRNAs in familial acne inversa (AI) patients with nicastrin (NCSTN) mutation. Objectives: The aim of this study was to explore the regulatory function of lncRNAs in familial AI patients with NCSTN mutation. Methods: The expression profiles of lncRNAs and mRNAs in skin tissues from familial AI patients with NCSTN mutation and healthy individuals were analysed in this study via RNA sequencing (RNA-seq). Results: In total, 359 lncRNAs and 1,863 mRNAs were differentially expressed between the two groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the dysregulated mRNAs targeted by lncRNAs were mainly associated with the immune regulation, Staphylococcus aureus infection and B cell receptor signalling pathways. The lncRNA-miRNA-mRNA coexpression network contained 265 network pairs comprising 55 dysregulated lncRNAs, 11 miRNAs, and 74 mRNAs. Conservation analysis of the differentially expressed lncRNAs between familial AI patients with NCSTN mutation and Ncstn keratinocyte-specific knockout (Ncstn^ΔKC) mice identified 6 lncRNAs with sequence conservation; these lncRNAs may participate in apoptosis, proliferation, and skin barrier function. Conclusions: These findings provide a direction for exploring the regulatory mechanisms underlying the progression of familial AI patients with NCSTN mutation.

Soluble adenylyl cyclase contributes to imiquimod-mediated inflammation and is a potential therapeutic target in psoriasis.

Cyclic AMP (cAMP) has a key role in psoriasis pathogenesis, as indicated by the therapeutic efficacy of phosphodiesterase inhibitors that prevent the degradation of cAMP. However, whether soluble adenylate cyclase (sAC) (encoded by the ADCY10 gene), which is an important source for cAMP, is involved in Th17 cell-mediated inflammation or could be an alternative therapeutic target in psoriasis is unknown. We have utilized the imiquimod model of murine psoriasiform dermatitis to address this question. Adcy10-/- mice had reduced erythema, scaling and swelling in the skin and reduced CD4+ IL17+ cell numbers in the draining lymph nodes, compared with wild-type mice after induction of psoriasiform dermatitis with imiquimod. Keratinocyte-specific knock out of Adcy10 had no effect on imiquimod-induced ear swelling suggesting keratinocyte sAC has no role in imiquimod-induced inflammation. During Th17 polarization in vitro, naive T cells from Adcy10-/- mice exhibited reduced IL17 secretion and IL-17+ T-cell proliferation suggesting that differentiation into Th17 cells is suppressed without sAC activity. Interestingly, loss of sAC did not impact the expression of Th17 lineage-defining transcription factors (such as Rorc and cMaf) but rather was required for CREB-dependent gene expression, which is known to support Th17 cell gene expression. Finally, topical application of small molecule sAC inhibitors (sACi) reduced imiquimod-induced psoriasiform dermatitis and Il17 gene expression in the skin. Collectively, these findings demonstrate that sAC is important for psoriasiform dermatitis in mouse skin. sACi may provide an alternative class of topical therapeutics for Th17-mediated skin diseases.

Interleukin-38 promotes skin tumorigenesis in an IL-1Rrp2-dependent manner.

Interleukin-38 (IL-38) is strongly associated with chronic inflammatory diseases; however, its role in tumorigenesis is poorly understood. We demonstrated that expression of IL-38, which exhibits high expression in the skin, is downregulated in human cutaneous squamous cell carcinoma and 7,12-dimethylbenzanthracene/12-O-tetradecanoyl phorbol-13-acetate-induced mouse skin tumorigenesis. IL-38 keratinocyte-specific knockout mice displayed suppressed skin tumor formation and malignant progression. Keratinocyte-specific deletion of IL-38 was associated with reduced expression of inflammatory cytokines, leading to reduced myeloid cell infiltration into the local tumor microenvironment. IL-38 is dispensable for epidermal mutagenesis, but IL-38 keratinocyte-specific deletion reduces proliferative gene expression along with epidermal cell proliferation and hyperplasia. Mechanistically, we first demonstrated that IL-38 activates the c-Jun N-terminal kinase (JNK)/activator protein 1 signal transduction pathway to promote the expression of cancer-related inflammatory cytokines and proliferation and migration of tumor cells in an IL-1 receptor-related protein 2 (IL-1Rrp2)-dependent manner. Our findings highlight the role of IL-38 in the regulation of epidermal cell hyperplasia and pro-tumorigenic microenvironment through IL-1Rrp2/JNK and suggest IL-38/IL-1Rrp2 as a preventive and potential therapeutic target in skin cancer.

Interleukin-38 promotes skin tumorigenesis via regulation of epidermal cell hyperplasia and pro-tumorigenic microenvironment in an IL-1Rrp2-dependent manner.

Abstract As the newest member of the IL-1 family, interleukin-38 (IL-38) has strong associations with chronic inflammatory diseases. However, its roles in tumorigenesis and the underlying mechanism remain poorly understood. Here, we demonstrated that IL-38, which was highly expressed in skin, downregulated in human cutaneous squamous cell carcinomas (CSCC) and 7,12-dimethylbenzanthracene (DMBA)/12-O-tetradecanoyl phorbol-13-acetate (TPA) induced mouse skin tumorigenesis. IL-38 keratinocyte-specific knockout mice (IL-38 cKO) dramatically promoted skin tumor formation and their malignant progression. Mechanistically, IL-38 is dispensable for epidermal mutagenesis. IL-38 keratinocyte-specific deletion reduced proliferative gene expression along with epidermal cell proliferation and hyperplasia. Additionally, keratinocyte-specific deletion of IL-38 was associated with reduced secretion of inflammatory cytokines leading to a decreased infiltration of myeloid cells into the local tumor microenvironment, these inflammation-driven tumorigenesis are essential for carcinogenesis process. Furthermore, we first demonstrated that IL-38 activated the c-Jun N-terminal kinase (JNK)/activator protein 1 (AP-1) signal transduction pathway to promote proliferation and migration of tumor cells and expression of cancer-related inflammatory cytokines in an IL-1 receptor (IL-1R)-related protein 2 (IL-1Rrp2)-dependent manner. Together, our findings highlight the role of IL-38 in the regulation of epidermal cell hyperplasia and pro-tumorigenic microenvironment through IL-1Rrp2 /JNK and establish a new defined factor IL-38/ IL-1Rrp2 as therapeutic targets in skin cancer.

Keratinocyte-specific knockout mice models via Cre–loxP recombination system

The Cre recombinase/loxP (Cre/loxP) system has emerged as a useful tool in genetic manipulations. Generally, any DNA sequence of interest can be deleted when flanked with loxP sites. The conditional (timely or spatially controlled) expression of Cre recombinase enables to determine, where (e.g. in which cell type or tissue) and when (at which time of life or of developmental stage of cells/tissues) the deletion of the floxed DNA sequence should occur. Therefore, two mouse lines are usually needed for conditional site-specific genome modification. This review aims to provide a general overview of the Cre/loxP system, elaborate on the different keratinocyte specific knockout mice used to study gene function in keratinocytes, and finally demonstrate the generation of a conditional knockout mice. Knockout mice have been efficient and powerful approach to understand the functions of specific genes in development and physiological homeostasis. However, deletion of the specific genes which are concerned in stages of development induces to embryonic lethality. To overcome this obstacle, Cre/loxP system has been used to delete a gene in a specific organ or tissue, or at a specific embryonic developmental stage. Conditional knockout mice have allowed extensive research of the epidermis and helped elucidate roles of many gene functions in keratinocytes.

232 Deficiency of Wnt5a in keratinocyte does not ameliorate the imiquimod-induced psoriasis-like dermatitis

Objective Wnt5a activated signalling cascades has been proved to be involved in the development of Psoriasis. However, the importance of keratinocyte produced Wnt5a in Psoriasis remained to be tested. The present study aimed to determine the effect of keratinocyte-specific knockout of Wnt5a on psoriasis-like dermatitis in imiquimod-induced mice. Methods Eight weeks old mice,in keratinocyte-specific knockout of Wnt5a (Wnt5a-cKO) mice and control littermates, were randomly assigned to receive topical application of Imiquimod (5% cream, 50mg) (IMQ) or control vihicle (VEH) on their shaved back for 7 days. Phenotypical presentation and severity index (PASI) modified from the human PASI guidelines to score scales, erythema, skin thickness of mouse back skin. Skin barrier was assayed by gpskin.Spleen index was calculated fluorescence activated cell sorter (FACS) was used to assess theratios of CD11+, CD68 +, and CD4 +, γσTCR+ T cell subsets in peripheral blood. Expression of β-catenin and its phosphorylation were detected by western blot and Immunofluorescence staining. Results PASI score showed significantly higher score in IMQ treated mice, with no significant difference between cKO and control littermates.Skin barrier assay showed increased skin barrier score and TEWL in IMQ treated mice in both cKO and control littermates.IMQ induced mild splenomegaly with non-significant higher spleen index compared to VEH treated mice, FACS profiles showed increased levels or ratios of CD11+, CD68 +, and CD4 +, γσTCR+ T cell subsets by IMQ stimulation in both cKO and control.Western blot analysis indicated that phosphorylation of β-catenin was markedly enhanced in control littermates, but not cKO mice, after 1 week IMQ treatment. Conclusions These results indicate that keratinocyte produced wnt5a is not nessecary for psoriasis-like dermatitis development in imiquimod-induced mice,even though the enhanced phosphorylation of β-catenin by IMQ stimulation was repressed in wnt5a cKO mice.

831 ARHGAP29 regulates keratinocyte migration in vitro but not in vivo

ARHGAP29 is a Rho GTPase Activating Protein with a high affinity for the small GTPase RhoA. In endothelial cells, ARHGAP29 regulates tubulogenesis and endothelial barrier function. However, very little is know about the role of ARHGAP29 in keratinocytes. We previously demonstrated that ARHGAP29 was reduced in Irf6-deficient skin and keratinocytes. Beause IRF6 is required for keratinocyte migration, we hypothesize that ARHGAP29 also regulates keratinocyte migration. To test this hypothesis, we used CRISPR-Cas9 technology to generate keratinocyte cell lines possessing two mutant alleles for ARHGAP29. ARHGAP29 mutant keratinocytes had more rounded cell morphology, irregular cellular edges and a disorganized actin cytoskeleton. We also observed an increased incidence of cellular blebbing, a phenomenon previously associated with increased RhoA activity. Using these cells, we performed in vitro scratch assays and observed that ARHGAP29 mutant keratinocytes were significantly delayed in their ability to close the scratch. Live imaging analysis of individual cells at the scratch edge showed that ARHGAP29 mutant keratinocytes migrated with significantly reduced migration speed, directionality, and persistence. To test a similar role for ARHGAP29 in vivo, we generated a keratinocyte-specific knockout of Arhgap29. These animals were viable and did not exhibit macroscopic cutaneous defects. Following excisional wounds, keratinocyte migration was not altered 7 days post-injury. Together, these data demonstrate that ARHGAP29 is required for proper keratinocyte morphology and migration in vitro, and additional wound healing time points will be needed to fully investigate the function of ARHGAP29 in in vivo keratinocyte migration.

STIM1 Thermosensitivity Defines the Optimal Preference Temperature for Warm Sensation in Mice

Mammals possess a remarkable ability to sense subtle temperature deviations from the thermoneutral skin temperature of ~33 °C, which ensures precise warm sensation. However, the underlying mechanisms remain unclear. Here we show that STIM1, an endoplasmic reticulum (ER) resident transmembrane protein that responds to both ER Ca2+ depletion and heat, mediates temperature-induced Ca2+ influx in skin keratinocytes via coupling to Orai Ca2+ channels in plasma membrane. Behaviorally, the keratinocyte-specific knockout of STIM1 shifts the optimal preference temperature (OPT) of mice from ~32 °C to ~34 °C, resulting in a strikingly reversed preference between 32 °C and 34 °C. Importantly, the thermally inactive STIM1-ΔK knock-in mice show altered OPT and warm preference behaviors as well, demonstrating the requirement of STIM1 thermosensitivity for warm sensation. Furthermore, the wild-type and mutant mice prefer temperatures closer to their respective OPTs, but poorly distinguish temperatures that are equally but oppositely deviated from their OPTs. Mechanistically, keratinocyte STIM1 affects the in vivo warm responses of sensory neurons by likely involving TRPA1 as a downstream transduction channel. Collectively, our data suggest that STIM1 serves as a novel in vivo thermosensor in keratinocytes to define the OPT, which might be utilized as a peripheral reference temperature for precise warm sensation.

IL-6 Negatively Regulates IL-22Rα Expression on Epidermal Keratinocytes: Implications for Irritant Contact Dermatitis.

Irritant Contact Dermatitis (ICD) is characterized by epidermal hyperplasia and inflammatory cytokine release. IL-6 has been shown to be involved in the pathogenesis of ICD; however, the involvement of the IL-22/IL-22Rα axis and its relation to IL-6 in the inflammatory response following irritant exposure are unknown. Using a chemical model of ICD, it was observed that mice with a keratinocyte-specific knockout of IL-6Rα (IL-6RαΔker) presented with increased inflammation and IL-22Rα and IL-22 protein expression relative to WT following irritant exposure, indicating that IL-6Rα deficiency in epidermal keratinocytes leads to the upregulation of IL-22Rα and its ligand during ICD. Furthermore, it was shown that IL-6 negatively regulates the expression of IL-22Rα on epidermal keratinocytes. This effect is functional as the effects of IL-22 on keratinocyte proliferation and differentiation were markedly reduced when keratinocytes were pretreated with IL-6 prior to IL-22 treatment. These results show that IL-6 modulates the IL-22/IL-22Rα axis in the skin and suggest that this occurrence may be associated with the increased epidermal hyperplasia and exacerbated inflammatory response observed in IL-6RαΔker mice during ICD.

STIM1 thermosensitivity defines the optimal preference temperature for warm sensation in mice.

Mammals possess a remarkable ability to sense subtle temperature deviations from the thermoneutral skin temperature of ~33 °C, which ensures precise warm sensation. However, the underlying mechanisms remain unclear. Here we show that STIM1, an endoplasmic reticulum (ER) resident transmembrane protein that responds to both ER Ca2+ depletion and heat, mediates temperature-induced Ca2+ influx in skin keratinocytes via coupling to Orai Ca2+ channels in plasma membrane. Behaviorally, the keratinocyte-specific knockout of STIM1 shifts the optimal preference temperature (OPT) of mice from ~32 °C to ~34 °C, resulting in a strikingly reversed preference between 32 °C and 34 °C. Importantly, the thermally inactive STIM1-ΔK knock-in mice show altered OPT and warm preference behaviors as well, demonstrating the requirement of STIM1 thermosensitivity for warm sensation. Furthermore, the wild-type and mutant mice prefer temperatures closer to their respective OPTs, but poorly distinguish temperatures that are equally but oppositely deviated from their OPTs. Mechanistically, keratinocyte STIM1 affects the in vivo warm responses of sensory neurons by likely involving TRPA1 as a downstream transduction channel. Collectively, our data suggest that STIM1 serves as a novel in vivo thermosensor in keratinocytes to define the OPT, which might be utilized as a peripheral reference temperature for precise warm sensation.

SMAD7 in keratinocytes promotes skin carcinogenesis by activating ATM-dependent DNA repair and an EGFR-mediated cell proliferation pathway.

SMA- and MAD-related protein 7 (SMAD7) is a general inhibitor of transforming growth factor-β (TGF-β) signaling that acts through interaction and degradation of TGF-β receptors. SMAD7 has been demonstrated to be transcriptionally upregulated in chemical-induced skin tumors and TGF-β-treated normal keratinocytes. To evaluate the function of SMAD7 in skin carcinogenesis in vivo, Smad7 transgenic mice that specifically express either wild-type (WT) SMAD7 (TG-Smad7-WT) or mutant SMAD7 (TG-Smad7-MT) in keratinocytes, as well as Smad7 keratinocyte-specific knockout (Smad72f/2f-K14Cre) mice, were subjected to chemical-induced skin carcinogenesis. WT-SMAD7-expressing transgenic mice showed significantly greater papilloma formation than did non-TG control and Smad7-MT mice. The expression of WT-SMAD7 attenuated DNA damage-induced apoptosis in epidermal keratinocytes by stimulating the ATM-dependent DNA repair pathway. Nonetheless, overexpression of WT-SMAD7 caused a susceptibility to 12-O-tetradecanoylphorbol-13-acetate-induced epidermal hyperproliferation through activation of epidermal growth factor (EGF) signaling. In agreement with the transgenic mouse data, keratinocyte-specific deletion of SMAD7 markedly suppressed the tumor formation by inhibiting ATM and epidermal growth factor receptor (EGFR) signaling. Moreover, specific inhibition of EGFR signaling attenuated the hyperproliferation and tumor formation in TG-Smad7-WT mice. Taken together, these data support a novel role for SMAD7 as a tumor promoter in skin carcinogenesis where SMAD7 stimulates the DNA repair pathway and EGFR signaling activation.

Inducible basal keratinocyte-specific knockout of the LamA3 gene: A model for wound healing and fibrosis?

Inducible basal keratinocyte-specific knockout of the LamA3 gene: A model for wound healing and fibrosis?

Abstract 2106: Twist1 regulates keratinocyte stem cell proliferation and migration and is required for skin tumor formation

Abstract Twist1 is a basic helix-loop-helix transcription factor and is known to play a role in tumor progression through regulation of genes involved in epithelial-mesenchymal transition. Twist1 is a known transcriptional target of signal transducer and activator of transcription-3 (Stat3). In previous studies, Stat3 was shown to play a role in skin tumor progression in the two-stage skin carcinogenesis model, at least in part, by regulating the levels of Twist1. Recent studies using keratinocyte-specific knockout (KO) of Twist1 indicate that Twist1 regulates keratinocyte proliferation during skin tumor promotion. Western blot analysis of lysates from both Twist1 deficient mouse primary keratinocytes and from epidermis isolated from BK5.Cre x Twist1flox/flox mice indicated that Twist1 KO leads to reduced levels of the cell cycle proteins Cyclin E1, E2F1, and Cdk2 and increased expression of p21 following treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). ChIP analysis of epidermal lysates from BK5.Cre x Twist1flox/flox mice revealed that Twist1 bound to the promoter regions of Cyclin E1, E2F1, and c-Myc, indicating direct transcriptional regulation of these cell cycle regulators. Moreover, Twist1 KO in keratinocytes impeded cell cycle progression by reducing the number of cells that advanced to S-phase. Further analyses have demonstrated that deletion of Twist1 either in primary keratinocytes or in vivo leads to an upregulation of p53, which is responsible for the increased expression of p21 observed in these cells. Keratinocyte specific deletion of Twist1 in vivo suppressed epidermal proliferation induced by TPA treatment compared to that observed in wild-type (WT) mice. To further characterize the potential role of Twist1 during epithelial carcinogenesis, we analyzed the impact of Twist1 deletion in vivo on bulge region keratinocyte stem cells (KSCs). Keratinocyte specific deletion of Twist1 in vivo led to a significant reduction in the number of label-retaining cells as well as the number of α6-integrin+/CD34+ cells in the hair follicles of untreated mice. An ongoing two-stage skin carcinogenesis experiment shows that BK5.Cre x Twist1flox/flox mice have significantly reduced tumor development as observed by decreased tumor multiplicity and delayed latency compared WT mice. Furthermore, tumors that developed in BK5.Cre x Twist1flox/flox mice have significantly reduced size compared to tumors on WT mice. Collectively, these findings suggest that Twist1 has a novel role in epithelial carcinogenesis by regulating proliferation and migration of keratinocytes and KSCs. Research supported by RP140108, CA76520, and T32 ES007247. Citation Format: Jaya Srivastava, Okkyung Rho, John DiGiovanni. Twist1 regulates keratinocyte stem cell proliferation and migration and is required for skin tumor formation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2106. doi:10.1158/1538-7445.AM2015-2106

Targeted Disruption of Glutathione Peroxidase 4 in Mouse Skin Epithelial Cells Impairs Postnatal Hair Follicle Morphogenesis that Is Partially Rescued through Inhibition of COX-2

Selenoproteins are essential molecules for the mammalian antioxidant network. We previously demonstrated that targeted loss of all selenoproteins in mouse epidermis disrupted skin and hair development and caused premature death. In the current study we targeted specific selenoproteins for epidermal deletion to determine whether similar phenotypes developed. Keratinocyte-specific knockout mice lacking either the glutathione peroxidase 4 (GPx4) or thioredoxin reductase 1 (TR1) gene were generated by cre-lox technology using K14-cre. TR1 knockout mice had a normal phenotype in resting skin while GPx4 loss in epidermis caused epidermal hyperplasia, dermal inflammatory infiltrate, dysmorphic hair follicles and alopecia in perinatal mice. Unlike epidermal ablation of all selenoproteins, mice ablated for GPx4 recovered after 5 weeks and had a normal lifespan. GPx1 and TR1 were upregulated in the skin and keratinocytes of GPx4 knockout mice. GPx4 deletion reduces keratinocyte adhesion in culture and increases lipid peroxidation and COX-2 levels in cultured keratinocytes and whole skin. Feeding a COX-2 inhibitor to nursing mothers partially prevents development of the abnormal skin phenotype in knockout pups. These data link the activity of cutaneous GPx4 to the regulation of COX-2 and hair follicle morphogenesis and provide insight into the function of individual selenoprotein activity in maintaining cutaneous homeostasis.