Squamous cell carcinomas and increased apoptosis in skin with inhibited Rel/nuclear factor-kappaB signaling.
(17/1203)
The Rel/nuclear factor-kappaB (Rel/NF-kappaB) transcription factors have been implicated previously in control of apoptosis, cell proliferation, and oncogenesis. Here we show that selective inhibition of Rel/NF-kappaB signaling in murine skin, by targeted overexpression of a super-repressor form of IkappaB-alpha, results in an increased basal frequency of apoptotic cells and the spontaneous development of squamous cell carcinomas. Presence of hyperplasia and hair follicle degeneration demonstrate an important role for Rel/NF-kappaB signaling in normal epidermal development and homeostasis. Transgenic skin, in addition, showed an enhanced sensitivity to UV-induced apoptosis. These data suggest an involvement of the Rel/NF-kappaB signaling pathway in apoptosis and cancer development of the skin. (+info)
Successful treatment of alopecia areata-like hair loss with the contact sensitizer squaric acid dibutylester (SADBE) in C3H/HeJ mice.
(18/1203)
A type of hair loss closely resembling human alopecia areata has been described in C3H/HeJ mice. In order to test the assumed analogy with human alopecia areata, we investigated the efficacy of treatment with the contact allergen squaric acid dibutylester. In 12 C3H/HeJ mice with alopecia areata an allergic contact dermatitis was induced and elicited weekly on one side of the back by topical applications of squaric acid dibutylester. Overt hair regrowth was observed only on the treated side of the back in nine of 12 mice. Histopathologic examination revealed a change in the distribution of the inflammatory infiltrate from a dense perifollicular lymphocytic infiltrate around the mid and lower regions of hair follicles in untreated skin to a uniform presence in the upper dermis in treated skin. Immunohistomorphometric studies revealed that treatment with squaric acid dibutylester increased the CD4+/CD8+ ratio from approximately 1:2 in untreated alopecia areata to 1:1 in treated alopecia areata. Additional immunohistochemical investigations showed an aberrant expression of major histocompatibility complex class I, major histocompatibility complex class II and intercellular adhesion molecule 1 on keratinocytes of the mid and lower parts of hair follicles in untreated alopecia areata. In successfully treated skin ectopic major histocompatibility complex class I and II expression was clearly reduced, whereas intercellular adhesion molecule 1 expression showed only minor changes. In conclusion, alopecia areata-like hair loss in C3H/HeJ mice responded to treatment with the contact sensitizer squaric acid dibutylester analogous to human alopecia areata. Moreover, successful treatment changes the aberrant expression of major histocompatibility complex class I and II in a way similar to that observed in human alopecia areata. These observations support the concept that alopecia areata-like hair loss in C3H/HeJ mice can be utilized as an appropriate model for the study of human alopecia areata. (+info)
1.3 kilobases of the lung type I cell T1alpha gene promoter mimics endogenous gene expression patterns during development but lacks sequences to enhance expression in perinatal and adult lung.
(19/1203)
The T1alpha gene is one of few markers for the type I cell phenotype in the adult mammalian lung. Type I cells form a large, thin epithelial layer that facilitates gas exchange and transport of fluids between the air spaces and capillaries. The T1alpha gene has a complex pattern of developmental expression in lung and brain; in vitro studies indicate that expression is regulated in part by thyroid transcription factor 1, forkhead proteins, and Sp1/Sp3 proteins. To explore the mechanisms that confine T1alpha expression in intact adult animals to alveolar type I and choroid plexus epithelial cells, we generated mice bearing a 1.3-kb T1alpha promoter-chloramphenicol acetyltransferase (CAT) gene. In situ hybridization and RNase protection assays show that the 1.3-kb promoter confers a pattern of CAT expression that largely matches the endogenous T1alpha in embryos and mid-term fetuses in lung and central nervous system. However, the 1.3-kb promoter lacks elements important for perinatal up-regulation of T1alpha in the lung and maintenance of that expression in the adult lung and brain. The final adult pattern of T1alpha expression may be directed by elements outside the 1.3-kb fragment, perhaps those 5' to the 1.3-kb fragment as we show herein, or in 3' and intronic regions. Dev Dyn 1999;215:319-331. (+info)
The TGF-beta2 isoform is both a required and sufficient inducer of murine hair follicle morphogenesis.
(20/1203)
Hair follicle development serves as an excellent model to study control of organ morphogenesis. Three specific isoforms of TGF-beta exist which exhibit a distinct pattern of expression during hair follicle morphogenesis. To clarify the still elusive role of these factors in hair follicle development, we have used a combined genetic and functional approach: analysis of hair follicle development in mice with disruptions of the TGF-beta1, 2, and 3 genes was coupled with a direct functional test of the effect of added purified factors on fetal hair follicle development in skin organ cultures. TGF-beta2 null mice exhibited a profound delay of hair follicle morphogenesis, with a 50% reduced number of hair follicles. In contrast to hair follicle development, growth and differentiation of interfollicular keratinocytes proceeded unimpaired. Unlike TGF-beta2-/- mice, mice with a disruption of the TGF-beta1 gene showed slightly advanced hair follicle formation, while lack of the TGF-beta3 gene did not have any effects. Treatment of wild-type, embryonic skin explants (E14.5 or E15.5) with TGF-beta2 protein in either soluble form or slow release beads induced hair follicle development and epidermal hyperplasia, while similar TGF-beta1 treatment exerted suppressive effects. Thus, the TGF-beta2 isoform plays a specific role, not shared by the other TGF-beta isoforms, as an inducer of hair follicle morphogenesis and is both required and sufficient to promote this process. (+info)
Analysis of 1,25-dihydroxyvitamin D(3) receptors (VDR) in basal cell carcinomas.
(21/1203)
We have analyzed expression of 1,25-dihydroxyvitamin D(3) receptor (VDR) protein and mRNA in basal cell carcinomas (BCC) of human skin. VDR immunoreactivity in BCCs was compared with the staining pattern of the proliferation marker Ki-67 in the same tumors. Additionally, VDR staining was compared to staining pattern of apoptotic cells by terminal UTP nucleotide end labeling assay. Frozen sections of superficial type, nodular type, and fibrosing type BCCs were consistently immunoreactive for VDR (mAb 9A7gamma) with almost every tumor cell labeled (n = 15). In general, VDR staining was pronounced in peripheral tumor cells. VDR immunoreactivity was consistently stronger in tumor cells than in adjacent or unaffected epidermis. No visual correlation was found in BCCs comparing labeling patterns of Ki-67-positive or apoptotic cells and mAb 9A7gamma. VDR mRNA was increased in BCCs (n = 6) compared to normal human skin (n = 5), as revealed by reverse transcription-polymerase chain reaction analysis. Our findings indicate that VDR is strongly expressed in BCCs and may be involved in the growth regulation of this tumour, and VDR mRNA and protein are increased in BCCs as compared to normal human epidermis. (+info)
In vivo transduction of mouse epidermis with recombinant retroviral vectors: implications for cutaneous gene therapy.
(22/1203)
Gene-based therapies may provide a way to treat inherited skin disorders but current approaches suffer serious limitations. The surgical procedures required to transplant ex vivo modified keratinocytes are likely to result in scarring and contracture, thereby limiting the area that can be treated. In addition, none of the methods currently available for in vivo gene transfer to epidermis leads to long-term transgene expression. The goal of this study was to develop a means for in vivo gene transfer to epidermis that would result in long-term transgene expression. We report here the first successful in vivo gene transfer that results in sustained transgene expression in epidermis. Hyperplastic mouse skin was transduced by direct injection of VSV-G pseudotyped retroviral vectors encoding the LacZ reporter gene. In mice tolerant to beta-galactosidase (beta-gal), transgene expression was noted in hair follicles and interfollicular epidermis for the duration of the experiment (16 weeks after transduction). Based on the kinetics of epidermal turnover in mouse skin, expression for this length of time strongly suggests stem cell transduction. In immunocompetent mice intolerant to beta-gal, transgene expression was lost by 3 weeks after transduction, concurrent with the onset of host immune responses to the transgene product. (+info)
The interaction of hydrocortisone and thyroxine during fetal adipose tissue differentiation: CCAAT enhancing binding protein expression and capillary cytodifferentiation.
(23/1203)
Late-term fetal pigs from genetically obese dams have elevated levels of thyroid hormones and glucocorticoids, depressed levels of GH, larger fat cells and elevated lipogenesis than do fetal pigs from lean dams. We investigated the influence of elevated levels of thyroid hormones and glucocorticoids per se on adipose tissue traits by chronically treating hypophysectomized (hypox; d 70) fetal pigs between d 90 and 105 of gestation with either thyroxine (T4), hydrocortisone (HC), or the combination of T4 + HC. Treatment with T4 and T4 + HC increased serum T4 and IGF-I levels and enhanced skin and hair development. Treatment with HC and T4 + HC increased serum HC levels, fat cell size, and inner subcutaneous adipose tissue thickness. Quantitative analysis of stained adipose tissue sections indicated that T4 + HC treatment increased lipid accretion and fat cell cluster development more than did either hormone alone. The T4 + HC markedly increased apparent fat cell number, because there was only a 19% increase in fat cell size. A hypox-induced deficit in cytodifferentiation of capillaries associated with adipocytes was not influenced by T4, but was partially normalized by treatment with HC and T4 + HC. Immunocytochemical and Western blot analyses showed no influence of hormonal treatment on expression of three CCAAT enhancing binding protein (C/EBP) isoforms. However, expression of C/EBPdelta in adipose tissue was markedly reduced in control fetal pigs compared with hypox fetal pigs. These studies indicate that concurrent action of glucocorticoids and thyroid hormones may be the critical aspect of endocrine regulation of fetal adipogenesis. (+info)
Bikunin, a serine protease inhibitor, is present on the cell boundary of epidermis.
(24/1203)
Bikunin, which is an inhibitor of serine proteases, is widely distributed in human tissues, including liver, kidney, and mucous membranes of the stomach and colon. The aim of this study was to clarify whether bikunin is expressed in human epidermis and its appendages. Immunoblot analysis using a specific polyclonal antibody to bikunin revealed that a single 43 kDa protein is present in the cell lysate from the human keratinocyte cell line HaCaT. Immunohistochemically, dotted reaction products stained with anti-bikunin antibody were localized on the cell boundary in both basal and spinous cell layers, except on the cell boundary of the basal cells facing the basal membrane. There were no reaction products in the granular-horny cell layers. Reaction products stained with anti-bikunin antibody were also observed on the hair bulb cells and eccrine sweat gland cells, but not on apocrine sweat glands. Also, reaction products were observed on the luminal surface of the renal proximal tubules and in the cytoplasm of these cells. In immunoelectron microscopy, gold particles were observed on the cell membranes close to the desmosomal structures. Reverse transcription-polymerase chain reaction and northern blot analyses showed that mRNA specific for bikunin was expressed in HaCaT cells and human epidermal keratinocytes obtained from suction blisters, and was contained in a commercially available human keratinocyte cDNA preparation. These findings indicate that bikunin is expressed in keratinocytes and may play an important part in regulating keratinocytes in either mitosis or inflammation. (+info)