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J T Elder

Publications and source records attributed to J T Elder.

At least 37 records · Page 2Linked to original sources
PubMed1998

EGF stimulates transcription of CaN19 (S100A2) in HaCaT keratinocytes.

CaN19 (S100A2), a member of the S100 family of calcium-binding proteins, was originally isolated in a screen for tumor suppressor genes. Recent work from our laboratory suggests that CaN19 is likely to be an effector of the regenerative hyperplasia pathway of epidermal differentiation. As other work from our laboratory in a human skin organ culture model suggests that this response is mediated by activation of the epidermal growth factor (EGF) receptor and/or related receptors of the ErbB family, we asked whether CaN19 expression could be increased by organ culture and by EGF treatment of human keratinocytes. CaN19 was strongly induced after 24 h of organ culture, and its induction could be blocked by PD153035, a specific inhibitor of EGF receptor tyrosine kinase activity. EGF treatment of immortalized human keratinocytes (HaCaT cells) increased CaN19 mRNA levels by 4.5-fold within 8 h, and a corresponding increase in CaN19 protein was observed by western blotting. EGF treatment had no effect on the expression of five other members of the S100A gene cluster. As assessed by nuclear run-off assay, CaN19 transcription increased rapidly in response to EGF, reaching a maximum induction of 16-fold after 2 h. In contrast, EGF treatment had no detectable effects on the decay of CaN19 transcripts, which were long lived (t1/2 > 6 h) in the presence or absence of EGF. PD153035 also blocked CaN19 transcription and the accumulation of CaN19 mRNA and protein in HaCaT cells. These results demonstrate that EGF receptor activation selectively stimulates CaN19 gene expression at the transcriptional level in human keratinocytes, and support the hypothesis that CaN19 is an important mediator of regenerative epidermal hyperplasia.

Calcium-Binding Proteins↗
PubMed1998

Linkage analysis of human leukocyte antigen (HLA) markers in familial psoriasis: strong disequilibrium effects provide evidence for a major determinant in the HLA-B/-C region.

Although psoriasis is strongly associated with certain human leukocyte antigens (HLAs), evidence for linkage to HLA markers has been limited. The objectives of this study were (1) to provide more definitive evidence for linkage of psoriasis to HLA markers in multiplex families; (2) to compare the major HLA risk alleles in these families with those determined by previous case-control studies; and (3) to localize the gene more precisely. By applying the transmission/disequilibrium test (TDT) and parametric linkage analysis, we found evidence for linkage of psoriasis to HLA-C, -B, -DR, and -DQ, with HLA-B and -C yielding the most-significant results. Linkage was detectable by parametric methods only when marker-trait disequilibrium was considered. Case-control association tests and the TDT identified alleles belonging to the EH57.1 ancestral haplotype as the major risk alleles in our sample. Among individuals carrying recombinant ancestral haplotypes involving EH57. 1, the class I markers were retained selectively among affecteds four times more often than among unaffecteds; among the few affected individuals carrying only the class II alleles from the ancestral haplotype, all but one also carried Cw6. These data show that familial and "sporadic" psoriasis share the same risk alleles. They also illustrate that substantial parametric linkage information can be extracted by accounting for linkage disequilibrium. Finally, they strongly suggest that a major susceptibility gene resides near HLA-C.

Adult↗
PubMed1998

Retinoid regulation of heparin-binding EGF-like growth factor gene expression in human keratinocytes and skin.

Retinoic acid (RA) has profound effects on epidermal homeostasis; however, the molecular mechanisms by which retinoids regulate keratinocyte cell proliferation and differentiation are not well understood. Here we report that mRNA expression of heparin-binding EGF-like growth factor (HB-EGF), a member of the EGF family of growth factors, is induced by RA in human keratinocytes and skin, and is overexpressed in the context of epidermal hyperplasia in vivo. Treatment of normal adult human keratinocytes with micromolar concentrations of RA significantly induced the expression of HB-EGF. The response was efficiently blocked by specific inhibitors of ErbB tyrosine kinase activity, MAP kinase kinase (MEK), or p38 stress-activated protein kinase. RA also enhanced the induction of HB-EGF mRNA in human skin organ culture, an ex vivo model system displaying many similarities to wound healing in vivo. HB-EGF transcripts were markedly increased in human skin by topical treatment with RA under conditions known to provoke epidermal hyperplasia. HB-EGF transcripts were also markedly overexpressed in the hyperplastic epidermis of psoriatic lesions, relative to normal skin. These results support the hypothesis that the effects of RA on epidermal hyperplasia are mediated at least in part by HB-EGF, and suggest that signal transduction mechanisms other than or in addition to nuclear RA receptors contribute to this effect.

Cells, Cultured↗
PubMed1998

Human psoriatic skin in organ culture: comparison with normal skin exposed to exogenous growth factors and effects of an antibody to the EGF receptor.

Organ cultures were established from psoriatic lesional skin of 24 different individuals and maintained for 8 days under serum-free, growth-factor-free conditions. Nonlesional skin from 14 of the same individuals and normal skin from another 12 individuals were also maintained in organ culture. At the end of the incubation period, the tissues were fixed in formalin and examined histologically. Lesional skin continued to express features of psoriatic plaque, which included irregularly shaped epithelial cells arranged in a disorganized fashion, and elongation of the rete ridges with a thickening in their lower portion. Abnormal epidermal differentiation and separation of the upper epidermal layers from the lower layers was also a consistent feature. In contrast, nonlesional skin from psoriatic patients exhibited a histological appearance which resembled that of site-matched normal skin. When normal skin was exposed to a growth-factor-enriched culture medium during the 8-day incubation period, it exhibited a histological appearance similar to that of psoriatic skin. In addition to abnormal histological features, the psoriatic skin in organ culture released higher amounts of matrix metalloproteinase-9 (MMP-9; 92-kD gelatinase B/type IV collagenase) into the culture fluid than either nonlesional skin or normal skin. Organ cultures of psoriatic lesional skin from 6 individuals were maintained for 8 days in the presence of an antibody to the human epidermal growth-factor (EGF) receptor. The abnormal histological features of the psoriatic tissue were partially ameliorated in the presence of the antibody. These data suggest that growth factors which act through the EGF receptor help to maintain the psoriatic phenotype in organ culture. They also suggest that organ culture may provide a useful tool with which to elucidate the pathophysiological mechanisms of altered keratinocyte proliferation and differentiation in psoriasis.

Antibodies, Monoclonal↗
PubMed1997

Positional cloning of novel skin-specific genes from the human epidermal differentiation complex.

The epidermal differentiation complex, located on human chromosomal band 1q21, contains at least 20 genes expressed during epidermal differentiation. We constructed a 1.2-Mb YAC contig spanning the SPRR and S100 gene clusters. Restriction mapping and FISH confirmed the colinearity of the contig with the genomic restriction map (A. Volz et al., 1993, Genomics 18:92-99). However, the YAC clones revealed several additional restriction sites not previously detected in genomic DNA, presumably due to CpG methylation. Making use of cDNA selection, we have identified three novel cDNAs, all of which map to the SPRR/IVL region. All three transcripts are expressed at high levels in normal and psoriatic skin, but not in cultured keratinocytes or in a variety of cell lines and human tissues. The molecular cloning of this region provides a valuable tool for identifying additional epidermal differentiation genes and for elucidating the relationship between chromatin structure and gene expression during terminal differentiation.

Amino Acid Sequence↗
PubMed1997

CaN19 expression in benign and malignant hyperplasias of the skin and oral mucosa: evidence for a role in regenerative differentiation.

CaN19, a member of the S100 family of calcium-binding proteins, is known to be "underexpressed" in cultured breast carcinoma-derived cell lines relative to their normal counterparts. By Northern blotting, we confirm these results and find that CaN19 is also markedly "underexpressed" in several carcinoma-derived cell lines of the skin, oral mucosa, and urogenital tract. However, exceptions to the inverse correlation between CaN19 expression and malignancy have been identified, bringing into question the hypothesis that CaN19 functions as a tumor suppressor gene. Unexpectedly, CaN19 mRNA was strongly expressed in bulk specimens of basal and squamous cell carcinomas of the skin and oral cavity. However, in situ hybridization revealed only limited CaN19 expression in tumor cells themselves; the bulk of expression is localized to hyperplastic perilesional epidermis. Tumor cell expression of CaN19 was similar in primary and locally metastatic tumors, indicating that this gene is not necessarily down-regulated during tumor progression. Coordinate overexpression of CaN19 and the "hyperproliferalive" keratin K6a was observed only in tissues undergoing squamous differentiation. Taken together with other recent results from our laboratory, these findings suggest the hypothesis that CaN19 participates in an epidermal growth factor receptor-dependent pathway of regenerative squamous differentiation.

Basal Cell Carcinoma↗
PubMed1997

Evaluation of the hairless rat as a model for in vivo percutaneous absorption.

Percutaneous absorption of topically applied mannitol and progesterone was compared in vivo with the hairless and hairy rat. Urinary excretion and skin concentration profiles after topical application of mannitol demonstrated that hairless rat skin was a "leakier" barrier to percutaneous absorption of polar compounds than was hairy rat skin, independent of formulation. Liposomal, but not aqueous mannitol was retained in hairy rat skin (> 0.5% after 12 h), whereas only negligible amounts were retained in hairless rat skin, regardless of formulation. Progesterone absorption from hydroalcohol and liposomal formulations into hairless rat skin was about five times greater than that in hairy rat skin. Skin delipidization by acetone resulted in a dramatic reduction in the cutaneous barrier to systemic mannitol absorption, which was much more pronounced in hairy than in hairless rat skin. Histological findings of patulous cysts and enlarged, highly vascularized sebaceous glands in the hairless rat suggested that these structures may enhance polar pathways and provide a lipophilic reservoir relative to the fully developed hair follicles of the hairy rat. Collectively, the results document percutaneous absorption differences as a function of animal model, and also suggest that follicular structures make a major contribution to passive percutaneous absorption.

Acetone↗
PubMed1997

Evidence for two psoriasis susceptibility loci (HLA and 17q) and two novel candidate regions (16q and 20p) by genome-wide scan.

In a 12.5 cM genome-wide scan for psoriasis susceptibility loci, recombination-based tests revealed linkage to the HLA region (Zmax = 3.52), as well as suggestive linkage to two novel regions: chromosome 16q (60-83.1 cM from pter, Zmax = 2.50), and chromosome 20p (7.5-25 cM from pter, Zmax = 2.62). All three regions yielded P values < or = 0.01 by non-parametric analysis. Recombination-based and allele sharing methods also confirmed a previous report of a dominant susceptibility locus on distal chromosome 17q (108.2 cM from pter, Zmax = 2.09, GENEHUNTER P = 0.0056). We could not confirm a previously reported locus on distal chromosome 4q; however, a broad region of unclear significance was identified proximal to this proposed locus (153.6-178.4 cM from pter, Zmax = 1.01). Taken together with our recent results demonstrating linkage to HLA-B and -C, this genome-wide scan identifies a psoriasis susceptibility locus at HLA, confirms linkage to 17q, and recommends two novel genomic regions for further scrutiny. One of these regions (16q) overlaps with a recently-identified susceptibility locus for Crohn's disease. Psoriasis is much more common in patients with Crohn's disease than in controls, suggesting that an immunomodulatory locus capable of influencing both diseases may reside in this region.

Adult↗
PubMed1996

Lineage-specific CaN19 expression in human skin: lack of expression in normal melanocytes.

Although expression of CaN19 is reduced in cell lines derived from tumors of diverse origin, its expression in their normal counterparts has not been studied in detail. We find that CaN19 mRNA is expressed at very low to undetectable levels in normal melanocytes as well as malignant melanoma cell lines, confirming that CaN19 expression in normal cells is lineage-dependent.

Cells, Cultured↗
PubMed1996

Extraction of human epidermis treated with retinol yields retro-retinoids in addition to free retinol and retinyl esters.

Vitamin A, all-trans-retinol, is metabolized to retinoic acid in vivo by a tightly controlled two-step conversion. Retinoic acid then binds to nuclear receptors and modulates cellular proliferation and differentiation. Because only a small fraction of retinol applied topically can be metabolized to retinoic acid, alternative pathways of retinol metabolism in skin were investigated. Retinol (0.4%) was applied to adult human skin under occlusion for 6 h to 4 d. The conversion of retinol into various metabolites such as 14-hydroxy-4,14-retro-retinol, anhydroretinol, 4-oxo-retinol, retinyl esters, and retinyl glucuronides was investigated. The level of 14-hydroxy-retro-retinol was increased from undetectable at time 0 to 326 ng/g wet weight of tissue at 6 h (6% of the retinol level) and maintained approximately the same concentration at 24 h to 409 ng/g wet weight (1.9% of the retinol level); it decreased to 48 ng/g wet weight of tissue (12% of its maximum level) by 4 d. Anhydroretinol was undetectable at time 0, increased only slightly at 6 h, and remained at the same level. We did not detect 4-oxo-retinol. Because 14-hydroxy-retro-retinol was found in the retinol-treated areas, its effects on epidermis were compared with those of retinol. Topical application of trans-retinol (0.3%) significantly increased both epidermal thickness and cellular retinoic acid binding protein II mRNA, whereas 14-hydroxy-4,14-retro-retinol (0.3%) did not increase either of these well-characterized cutaneous retinoid responses. Retinol, when applied topically in pharmacologic doses to human epidermis, remained as free retinol, was metabolized primarily to retinol ester, and was metabolized to a lesser extent to retro-retinoids and didehydroretinol.

Adult↗
PubMed1996

Retinoid induction of CRABP II mRNA in human dermal fibroblasts: use as a retinoid bioassay.

Cellular retinoic acid binding protein II (CRABP II) mRNA is selectively induced by all-trans retinoic acid in human skin and dermal fibroblasts. In order to determine whether this response can be used as a reliable measure of retinoid potency and activity, we treated human skin fibroblasts for 24 h with increasing concentrations of several natural and synthetic retinoids. CRABP II mRNA levels were measured by quantitative Northern blotting and compared, when possible, with those obtained after topical application of the same retinoids to human skin. All eight active retinoids tested induced a concentration-dependent CRABP II mRNA response in the fibroblast assay. In contrast, one known inactive retinoid (meta-carboxy TTNPB), differing from the active form only in the position of the carboxyl substituent, failed to evoke a response. The fibroblast and human skin bioassays agreed with respect to relative potency and response amplitude for three of the three retinoids tested. Retinoic acid was approximately 10-fold more potent than retinal in both assays, suggesting that oxidation to retinoic acid underlies the activity of retinol in fibroblasts as well as in intact skin. In support of this hypothesis, treatment with liarozole, an inhibitor of P450-mediated retinoic acid oxidative catabolism, significantly increased fibroblast CRABP II mRNA levels and potentiated the effects of retinol by 1.5-fold at concentrations at which it had no effect on its own. Taken together, these results identify the fibroblast CRABP II response as a reproducible measure of retinoid bioactivity with promise as a predictor of human skin responses and further suggest that metabolism is an important determinant of retinoid bioactivity in vivo.

Biological Assay↗
PubMed1996

Assignment of psoriasin to human chromosomal band 1q21: coordinate overexpression of clustered genes in psoriasis.

Psoriasin is an abundant low molecular weight protein in keratinocytes from psoriatic lesions. Because of similarities in gene structure and expression to other genes on human chromosomal band 1q21, we hypothesized that psoriasin might also map to this region. To test this hypothesis, we identified and used a genomic lambda clone (lambda 9.2) as a probe for fluorescent in situ hybridization. lambda 9.2 detected the 1q21 region in 81% of 52 chromosomes 1 examined, although it also hybridized to acrocentric chromosomes. lambda 9.2 DNA yielded polymerase chain reaction amplification of 121-bp sequence colinear with psoriasin cDNA, as did genomic DNA from hybrid cell lines containing all or part of chromosome 1. The psoriasin gene was present on a 380-kb yeast artificial chromosome clone that was previously mapped to 1q21 and shown to contain calcyclin; here it is also shown to contain MRP8 and CaN19. Psoriasin and several other tightly linked 1q21 genes were markedly overexpressed in psoriatic lesions, suggesting a role for these clustered genes in the regulation of epidermal proliferation.

Base Sequence↗
PubMed1995

Application of retinol to human skin in vivo induces epidermal hyperplasia and cellular retinoid binding proteins characteristic of retinoic acid but without measurable retinoic acid levels or irritation.

We investigated the clinical, histologic, and molecular responses of normal human skin to all-trans-retinol (ROL) application, compared to those induced by topical all-trans-retinoic acid (RA), and measured ROL-derived metabolites. Up to 1.6% ROL, 0.025% RA in vehicle (70% ethanol/30% propylene glycol), or vehicle alone were applied in a double-blind fashion to normal buttock skin and occluded for 4 d. ROL produced from none to only trace erythema, which was clinically and statistically insignificant, whereas RA induced a significant 3.7-fold increase in erythema score compared to vehicle (n = 10, p < 0.01). However, ROL induced significant epidermal thickening (1.5-fold at 1.6% ROL, p < 0.01), similar to RA (1.6-fold at 0.025% RA, p < 0.01), relative to the vehicle. ROL, compared with vehicle, also increased mRNA levels of cellular retinoic acid binding protein (CRABP-II) and cellular retinol binding protein (CRBP) genes as determined by Northern analysis (5-6-fold and 6-7-fold, respectively) and riboprobe in situ hybridization. CRABP-II and CRBP protein levels were also higher following ROL than vehicle treatment, as measured by ligand binding (3.2-fold, p < 0.001; n = 7) and Western analysis (3.6-fold, p < 0.003; n = 6), respectively. Epidermal retinyl ester (RE) content, measured after removal of stratum corneum, rose 240-fold (p < 0.005, n = 5) by 24 h of ROL occlusion. RA content, however, was undetectable or detectable only at trace amounts in all samples obtained at 0, 6, 24, and 96 h after ROL occlusion. Detectability of RA was not correlated with ROL treatment (compared to untreated normal skin, p = 0.86) or baseline skin ROL levels (average r = -0.1, p > 0.3). These data demonstrate that ROL application 1) produces trace erythema not significantly different from vehicle, whereas RA causes erythema; 2) induces epidermal thickening and enhances expression of CRABP-II and CRBP mRNAs and proteins as does RA; 3) causes marked accumulation of retinyl ester; and 4) does not significantly increase RA levels. Taken together, the data are compatible with the idea that ROL may be a prohormone of RA, because it produces changes in skin similar to those produced by RA but without measurable RA or irritation.

Administration, Cutaneous↗
PubMed1995

Regulation of cellular retinoic acid binding protein expression in rhino mouse skin by all-trans-retinoic acid.

Cellular retinoic acid binding proteins (CRABP) are cytoplasmic proteins that bind all-trans-retinoic acid (RA) and other retinoids. The purpose of these studies was to determine the effects of topically applied RA on CRABP expression in rhino mouse skin. CRABP-II mRNA was significantly induced (3- to 4.5-fold) by a single dose of RA at 6 and 16 h after RA treatment, with a return to control levels at 48 h. CRABP-II message was not significantly elevated by 3 or 4 consecutive days of RA treatment, when assessed 24 h after the last treatment. CRABP-I mRNA was undetectable in control and RA-treated skin. We used radiolabelled RA binding combined with non-denaturing PAGE blot autoradiography to distinguish the CRABP subtypes. By this protein assay method, increases in CRABP-II were detected 24 and 48 h after a single application of RA, as well as after 3 and 4 days of RA treatment. RA treatment did not alter CRABP-I expression relative to the vehicle control. These results demonstrate that in mouse skin CRABP-II, but not CRAB-I, is inducible by RA, and is similar to how RA regulates CRABP in human skin.

Animals↗
PubMed1994

Direct evidence for homologous sequences on the paracentric regions of human chromosome 1.

Calcyclin is a member of the S100 family of proteins, many of which are encoded by genes that have been localized to the proximal long arm of human chromosome 1 (bands q21-q22). A 450-kb yeast artificial chromosome clone containing the human calcyclin gene was identified by PCR screening and used as a probe for fluorescence in situ hybridization (FISH). Along with the expected hybridization to 1q21, simultaneous, specific hybridization to the centromeric region of the short arm of chromosome 1 was also observed. An identical pattern of hybridization was observed when microdissected 1q21 DNA sequences were used as a probe for FISH, confirming the presence of homologous sequences flanking both sides of the centromere of human chromosome 1. These results are consistent with a model in which human chromosome 1 arose by insertion of the centromere and heterochromatin into an ancestral chromosome containing chromosome-specific repetitive sequences.

Animals↗
PubMed1994

Epidemiology and the genetics of psoriasis.

Several lines of compelling epidemiologic evidence indicate that susceptibility to psorasis is inherited, albeit not in a simple monogenic fashion. Psoriasis is one of a number of diseases with a presumed autoimmune pathogenesis that display significant human leukocyte antigen (HLA) associations. However, only a small fraction of those who carry the implicated HLA susceptibility alleles develop disease. Taken together with the epidemiologic data indicative of high heritability, this observations suggests that one or more loci in addition to HLA are necessary for the development of psoriasis. As the identity of these other genes is unknown, genetic linkage analysis offers an attractive strategy for their identification. To this end, we have initiated a large linkage study of multiplex psoriasis kindreds, and PCR-based genotyping of CA repeat polymorphisms has been performed for several markers in the HLA region (6p21.3). As expected given the hypothesis of oligogenic inheritance, these analyses have thus far failed to reveal tight linkage of psoriasis to the 6p21 region. Nevertheless, the substantial homogeneity of the psoriatric phenotype and the clear evidence for increased HLA association and heritability in juvenile onset disease (40 years) indicate that, like insulin-dependent diabetes mellitus, psoriasis is an HLA-associated, genetically complex disease whose etiology is potentially amenable to elucidation through linkage analysis.

Alleles↗
PubMed1994

Of genes and antigens: the inheritance of psoriasis.

Psoriasis is one of a number of autoimmune diseases that display significant HLA associations. In particular, individuals with onset of disease prior to 40 years of age display striking associations with HLA-Cw6 and are much more likely to have a positive family for psoriasis. However, only about 10% of Cw6-positive individuals develop disease, suggesting that other genetic and/or environmental factors must be involved. Several compelling lines of epidemiologic evidence indicate that psoriasis susceptibility is inherited, albeit not in a simple monogenic fashion, and that genetic, rather than environmental, factors are primarily responsible for the variability in inheritance of psoriasis. Taken together, these observations suggest that one or more loci in addition to HLA are necessary for the development of psoriasis. The number of additional loci is likely to be small, because i) the disease is very common ii) substantial excess risk of psoriasis is observed in first degree relatives, and iii) nevoid variants of psoriasis have been reported, suggestive of somatic mutation of a single gene during development. The substantial homogeneity of the psoriatic phenotype and the clear evidence for increased HLA association and heritability in juvenile onset disease indicate that despite its complexity, psoriasis is a common disease whose etiology is amendable to elucidation through the techniques of modern molecular genetics.

Age of Onset↗