Sebaceous tumours contain a subpopulation of cells expressing the keratin 15 stem cell marker.
Explore the source record for details and available documents.
Biomarkers, Tumor↗
Biomedical subjects
S Lyle
Publications and source records attributed to S Lyle.
Indian hedgehog and beta-catenin signaling: role in the sebaceous lineage of normal and neoplastic mammalian epidermis.
In mammalian epidermis, the level of beta-catenin signaling regulates lineage selection by stem cell progeny. High levels of beta-catenin stimulate formation of hair follicles, whereas low levels favor differentiation into interfollicular epidermis and sebocytes. In transgenic mouse epidermis, overexpression of beta-catenin leads to formation of hair follicle tumors, whereas overexpression of N-terminally truncated Lef1, which blocks beta-catenin signaling, results in spontaneous sebaceous tumors. Accompanying overexpression of beta-catenin is up-regulation of Sonic hedgehog (SHH) and its receptor, Patched (PTCH/Ptch). In DeltaNLef1 tumors Ptch mRNA is up-regulated in the absence of SHH. We now show that PTCH is up-regulated in both human and mouse sebaceous tumors and is accompanied by overexpression of Indian hedgehog (IHH). In normal sebaceous glands IHH is expressed in differentiated sebocytes and the transcription factor GLI1 is activated in sebocyte progenitors, suggesting a paracrine signaling mechanism. PTCH1 and IHH are up-regulated during human sebocyte differentiation in vitro and inhibition of hedgehog signaling inhibits growth and stimulates differentiation. Overexpression of DeltaNLef1 up-regulates IHH and stimulates proliferation of undifferentiated sebocytes. We present a model of the interactions between beta-catenin and hedgehog signaling in the epidermis in which SHH promotes proliferation of progenitors of the hair lineages whereas IHH stimulates proliferation of sebocyte precursors.
Animals↗
Atrichia caused by mutations in the vitamin D receptor gene is a phenocopy of generalized atrichia caused by mutations in the hairless gene.
Generalized atrichia with papules is a rare disorder characterized by loss of hair shortly after birth and development of cutaneous cysts. Mutations in the hairless gene (HR) cause this phenotype in both mouse and human. Here we present a case of atrichia with papules in a patient with a normal HAIRLESS gene but with mutations in both alleles of the VITAMIN D RECEPTOR. The patient exhibited vitamin D resistant rickets, which was confirmed by an absent response of her fibroblasts to 1,25-dihydroxyvitamin D3 in vitro. Similar to individuals with HAIRLESS mutations, her skin showed an absence of normal hair follicles and the presence of follicular remnants and cysts. The cyst epithelium contained keratin-15- and keratin-17-positive cells suggesting derivation from the hair follicle bulge and the presence of epithelial stem cells. Although hair loss has been reported in association with hereditary vitamin D resistant rickets, we now characterize this alopecia as clinically and pathologically indistinguishable from generalized atrichia with papules, which was previously thought to be caused only by mutations in HAIRLESS. These findings suggest that VDR and HR, which are both zinc finger proteins, may be in the same genetic pathway that controls postnatal cycling of the hair follicle.
Alopecia↗
Protection against pemphigus foliaceus by desmoglein 3 in neonates.
Explore the source record for details and available documents.
Adult↗
TIA-1 positive tumor-infiltrating lymphocytes in nevi and melanomas.
Tumor-infiltrating lymphocytes (TIL) have been shown to be an independent prognostic factor in melanomas. To better characterize the host immune response, we have classified TIL by their immunoreactivity against lymphoid markers in formalin-fixed, paraffin-embedded tissue. Monoclonal antibodies to leukocyte common antigen (LCA) and TIA-1 (a granule-associated protein of cytotoxic T cells and NK cells) were used to immunostain a series of benign nevi, nontumorigenic radial growth phase, and tumorigenic vertical growth phase melanomas and metastases. Among nine nevi, few LCA+ TIL were found, among which rare cells were positive for TIA-1 (mean, 2.0). Five nontumorigenic radial growth phase melanomas also had few total TIL and rare TIA-1+ TIL (mean, 3.4); the nontumorigenic radial growth phase component of seven tumorigenic vertical growth phase melanomas had higher numbers of TIA-1+ TIL (mean, 11). Twelve cases of tumorigenic vertical growth phase melanoma showed a variable but significantly greater number of both LCA+ TIL and TIA-1+ TIL (mean, 30.6). Nine cases of metastatic melanoma had a wide range of variation in LCA as well as in TIA-1+ TIL (mean, 46). Although the mean total number of TIA-1+ TIL increased from nontumorigenic radial growth phase to tumorigenic vertical growth phase to metastases, TIA-1+ as a percentage of TIL declined across these categories of tumor progression (42%, 31%, and 26%, respectively). Our results show that these attributes of TIA-1+ TIL, both increasing total number but decreasing percentage, appear to be a marker of tumor progression of malignant melanomas. In addition, there was significant variability in the number of TIA-1+ TIL among advanced melanomas, raising the possibility that an assessment of TIA-1+ TIL may prove a useful prognostic tool for the evaluation of primary melanomas.
Humans↗
Chemical modification and site-directed mutagenesis of conserved HXXH and PP-loop motif arginines and histidines in the murine bifunctional ATP sulfurylase/adenosine 5'-phosphosulfate kinase.
The sulfurylase domain of the mouse bifunctional enzyme ATP sulfurylase/adenosine 5'-phosphosulfate (APS) kinase contains HXXH and PP-loop motifs. To elucidate the functional importance of these motifs and of conserved arginines and histidines, chemical modification and site-directed mutagenesis studies were performed. Chemical modification of arginines and histidines with phenylglyoxal and diethyl pyrocarbonate, respectively, renders the enzyme inactive in sulfurylase, kinase, and overall assays. Data base searches and sequence comparison of bifunctional ATP sulfurylase/APS kinase and monofunctional ATP sulfurylases shows a limited number of highly conserved arginines and histidines within the sulfurylase domain. Of these conserved residues, His-425, His-428, and Arg-421 are present within or near the HXXH motif whereas His-506, Arg-510, and Arg-522 residues are present in and around the PP-loop. The functional role of these conserved residues was further studied by site-directed mutagenesis. In the HXXH motif, none of the alanine mutants (H425A, H428A, and R421A) had sulfurylase or overall activity, whereas they all exhibited normal kinase activity. A slight improvement in reverse sulfurylase activity (<10% residual activity) and complete restoration of forward sulfurylase was observed with R421K. Mutants designed to probe the PP-loop requirements included H506A, R510A, R522A, R522K, and D523A. Of these, R510A exhibited normal sulfurylase and kinase activity, R522A and R522K showed no sulfurylase activity, and H506A had normal sulfurylase activity but produced an effect on kinase activity (<10% residual activity). The single aspartate, D523A, which is part of the highly conserved GRD sequence of the PP-loop, affected both sulfurylase and kinase activity. This mutational analysis indicates that the HXXH motif plays a role only in the sulfurylase activity, whereas the PP-loop is involved in both sulfurylase and kinase activities. Residues specific for sulfurylase activity have also been distinguished from those involved in kinase activity.
Amino Acid Sequence↗
Human hair follicle bulge cells are biochemically distinct and possess an epithelial stem cell phenotype.
Stem cells are vital for the homeostasis of self-renewing tissues and their manipulation may have wide ranging applications, including gene therapy, wound repair, and tissue transplantation. Although rodent hair follicle stem cells have been localized to the follicle bulge, the location of human hair follicle stem cells is less clear, and their characterization has been hampered by a lack of cellular markers for the bulge area. We demonstrate that the C8/144B monoclonal antibody, originally raised against a CD8 peptide sequence, immunostains the human hair follicle bulge. We show that this antibody recognizes cytokeratin 15 (K15) in keratinocytes, and that K15-positive bulge cells possess a stem cell phenotype characterized by their slowly cycling nature, proliferation at the onset of new hair follicle growth, and high level of beta1 integrin expression. These results localize human hair follicle stem cells to the bulge and suggest that K15 is preferentially expressed in epithelial stem cells.
Antibodies, Monoclonal↗
Histopathologic effects of radiofrequency catheter ablation in previously infarcted human myocardium.
INTRODUCTION: The use of catheter-based radiofrequency (RF) ablation for the treatment of ventricular tachyarrhythmias due to previous myocardial infarction has been steadily increasing. The histopathologic changes caused by this technique are not well described in humans. METHODS AND RESULTS: Three patients with hemodynamically tolerated ventricular tachycardias (VTs) due to previous myocardial infarction underwent endocardial mapping and catheter based RF ablation. All patients received between 5 and 11 RF lesions each of 60-second duration. One patient underwent myocardial resection of a left ventricular aneurysm 1 day following RF ablation, one expired 7 days after RF ablation, and one expired 9 months after RF ablation. None of the deaths occurred as a result of RF ablation. Pathologic specimens obtained early after RF ablation revealed areas of focal acute inflammation and fibrin deposition. Later specimens revealed several focal areas of fibrosis and granulation tissue. Specimens obtained late after RF ablation revealed a dense band of fibrosis, measuring 17 x 17 x 5 mm (1,250 mm3). CONCLUSION: Catheter-based RF ablation of ischemic VT in humans causes lesions that initially resemble coagulation necrosis. This is followed by the development of an inflammatory infiltrate and, finally, the development of fibrosis. Repeated application of RF ablation may result in much larger lesions than have been previously reported.
Aged↗
Cytokeratin 15 expression in trichoepitheliomas and a subset of basal cell carcinomas suggests they originate from hair follicle stem cells.
Trichoepitheliomas and many basal cell carcinomas appear to arise from the hair follicle, and in particular from the hair follicle bulge. This histogenesis is suggested from both morphological and immunohistochemical studies on tumor cells and stroma. Epithelial stem cells are thought to be important in tumorigenesis, and we previously localized a population of stem cells to the bulge area of the outer root sheath. We recently identified an anti-CD8 monoclonal antibody (DAKO clone C8/144B) that cross-reacts with cytokeratin 15 (K15), and serves as a specific marker for the bulge. In this study, we screened a series of trichoepitheliomas (n=13), basal cell carcinomas (n=37) and a variety of other skin tumors with this antibody. All trichoepitheliomas (100%) showed keratin 15 expression, while only a subset of basal cell carcinomas (27%) was K15-positive. Epidermal tumors, including squamous cell carcinomas, were K15-negative. Tumors of follicular derivation such as proliferating trichilemmal cysts were also K15-positive, while others such as pilomatricoma were K15-negative. Expression of K15 in trichoepitheliomas, some basal cell carcinomas and other follicular tumors suggests that these tumors are related to hair follicle stem cells in the bulge.
Antibodies, Monoclonal↗
Ultrasound-guided fine-needle aspiration diagnosis of adenocarcinoma of esophagus with signet-ring cell features arising in Barrett's esophagus: a case report.
We report a rarely documented case of adenocarcinoma of esophagus with signet-ring cell features arising in a Barrett's esophagus. This was diagnosed by employing combined endosonography and fine-needle aspiration cytology. The patient had progressive dysphagia and a poorly circumscribed mass involving the distal esophagus and gastroesophageal junction. An incisional biopsy was performed which showed Barrett's esophagus with highly atypical glands suspicious for adenocarcinoma. Following that, an ultrasound-guided endoscopic fine-needle aspiration revealed a cellular specimen with multiple groups and singly dispersed atypical glandular cells with a predominance of signet-rings features. These findings represented an adenocarcinoma with signet-ring cell features arise in Barrett's esophagus.
Adenocarcinoma↗
Sulfate activation and transport in mammals: system components and mechanisms.
Extensive studies on the mammalian sulfate-activating enzymes and PAPS translocase have enhanced our understanding of the overall pathway of sulfate activation and utilization. Isolation of the PAPS-synthesizing activities from rat chondrosarcoma and preparation of stable non-hydrolyzable analogs of APS and PAPS have facilitated the kinetic characterization of mammalian ATP sulfurylase and APS kinase. These studies provided the basis for further experimental work showing that APS, the labile intermediate product, is channeled directly between the sulfurylase and kinase active sites. The defect in the brachymorphic mutant mouse lies in this channeling mechanism, thus interfering with efficient PAPS production. The rat chondrosarcoma ATP sulfurylase and APS kinase activities, in fact, reside in a single bifunctional cytoplasmic protein, which has now been cloned and expressed. The mechanism by which PAPS reaches its sites of utilization in the Golgi lumen has also been elucidated: The PAPS translocase is a 230-kDa integral Golgi membrane protein which functions as an antiport.
Animals↗
The C8/144B monoclonal antibody recognizes cytokeratin 15 and defines the location of human hair follicle stem cells.
Stem cells are vital for the homeostasis of self-renewing tissues such as the hair follicle. Epithelial stem cells have been implicated in tumorigenesis and wound healing, and their manipulation may have wide ranging applications including gene therapy and tissue transplantation. Rodent hair follicle stem cells have been localized to an area of the follicle called the bulge, however, the identification and characterization of human hair follicle stem cells has been hampered by a lack of cellular markers for this area. We have determined that the C8/144B monoclonal antibody, originally generated against a short intracytoplasmic peptide of CD8, preferentially immunostains hair follicle bulge keratinocytes without staining the remaining hair follicle. Using expression cloning, we identified cytokeratin 15 as the keratinocyte protein recognized by the C8/144B monoclonal antibody. By delineating the bulge using this antibody, we demonstrated that bulge cells possess a stem cell phenotype characterized by their slowly-cycling nature, preferential proliferation at the onset of new hair follicle growth, high level of beta1 integrin expression, and expression of cytokeratin 19.
Adult↗
Burnout exists ... solutions lie within.
Explore the source record for details and available documents.
Burnout, Professional↗
Sulfate-activating enzymes in normal and brachymorphic mice: evidence for a channeling defect.
The severe reduction in the amount of 3'-phosphoadenosine 5'-phosphosulfate (PAPS) in cartilage from homozygous brachymorphic mice results from a decrease in the activities of both ATP sulfurylase (50%) and adenosine 5'-phosphosulfate (APS) kinase (14% of normal). In order to better understand the etiology of this double enzyme defect, a dual approach to elucidating the nature of the enzyme complex as well as its mechanistic properties was undertaken. Antibody reagents that react with both activities provide evidence for a single, bifunctional protein in both normal and mutant cartilage. Quantitative Western blot analysis indicates that a normal amount of a dysfunctional protein is produced in mutant cartilage. Kinetic studies show that the Vmax for mutant kinase is significantly reduced and that mutant sulfurylase and kinase appear to have lower KmAPS values than normal. Interestingly, the mutation appears to disrupt the channeling mechanism that has recently been demonstrated for this pathway [Lyle et al. (1994) Biochemistry 33, 6822-6827]. APS kinase from normal mouse cartilage utilizes APS supplied by ATP sulfurylase much more efficiently than APS which is added exogenously; i.e., channeling efficiency is > 90%. In contrast, the mutant enzymes exhibit only 54% channeling efficiency. Lastly, isotope dilution and enrichment experiments show directly that the APS binding sites of the mutant enzymes are more accessible to free APS than are those of the normal enzymes. These data suggest that the mutation primarily affects the catalytic properties of the PAPS activation system by altering the function of the novel coupling mechanism between the two activities, causing a decrease in the ability to channel APS and produce PAPS efficiently.
Animals↗
Kinetic mechanism of ATP-sulphurylase from rat chondrosarcoma.
ATP-sulphurylase catalyses the production of adenosine 5'-phosphosulphate (APS) from ATP and free sulphate with the release of PPi. APS kinase phosphorylates the APS intermediate to produce adenosine 3'-phosphate 5'-phosphosulphate (PAPS). The kinetic mechanism of rat chondrosarcoma ATP-sulphurylase was investigated by steady-state methods in the physiologically forward direction as well as the reverse direction. The sulphurylase activity was coupled to APS kinase activity in order to overcome the thermodynamic constraints of the sulphurylase reaction in the forward direction. Double-reciprocal initial-velocity plots for the forward sulphurylase intersect to the left of the ordinate for this reaction. KmATP and Kmsulphate were found to be 200 and 97 microM respectively. Chlorate, a competitive inhibitor with respect to sulphate, showed uncompetitive inhibition with respect to ATP with an apparent Ki of 1.97 mM. Steady-state data from experiments in the physiologically reverse direction also yielded double-reciprocal initial-velocity patterns that intersect to the left of the ordinate axis, with a KmAPS of 39 microM and a Kmpyrophosphate of 18 microM. The results of steady-state experiments in which Mg2+ was varied indicated that the true substrate is the MgPPi complex. An analogue of APS, adenosine 5'-[beta-methylene]phosphosulphate, was a linear inhibitor competitive with APS and non-competitive with respect to MgPPi. The simplest formal mechanism that agrees with all the data is an ordered steady-state single displacement with MgATP as the leading substrate in the forward direction and APS as the leading substrate in the reverse direction.
Adenosine Phosphosulfate↗
Kinetic mechanism of adenosine 5'-phosphosulphate kinase from rat chondrosarcoma.
Biosynthesis of the activated sulphate donor adenosine 3'-phosphate 5'-phosphosulphate (PAPS) involves the sequential action of two enzyme activities. ATP-sulphurylase catalyses the formation of APS (adenosine 5'-phosphosulphate) from ATP and free sulphate, and APS is then phosphorylated by APS kinase to produce PAPS. Initial-velocity patterns for rat chondrosarcoma APS kinase indicate a single-displacement formal mechanism with KmAPS 76 nM and KmATP = 24 microM. Inhibition studies using analogues of substrates and products were carried out to determine the reaction mechanism. An analogue of PAPS, adenosine 3'-phosphate 5'-[beta-methylene]phosphosulphate, exhibited competitive inhibition with APS and non-competitive inhibition with ATP. An analogue of APS, adenosine 5'-[beta-methylene]phosphosulphate was also competitive with APS and non-competitive with ATP. Adenosine 5'-[beta gamma-imido]triphosphate showed competitive inhibition with respect to ATP and produced mixed-type inhibition, with a pronounced intercept effect and a small slope effect, with respect to APS. These results are in accord with the formulation of the predominant pathway as a steady-state ordered mechanism with APS as the leading substrate and PAPS as the final product released.
Adenosine Phosphosulfate↗
Intermediate channeling between ATP sulfurylase and adenosine 5'-phosphosulfate kinase from rat chondrosarcoma.
Biosynthesis of the activated sulfate donor PAPS (3'-phosphoadenosine 5'-phosphosulfate) involves the sequential action of two enzyme activities. ATP sulfurylase catalyzes the formation of APS (adenosine 5'-phosphosulfate) from ATP and free sulfate, and APS is then phosphorylated by APS kinase to produce PAPS. Using rat chondrosarcoma ATP sulfurylase and APS kinase, a newly developed assay system, which permits measuring the accumulation of both APS and PAPS in the presence of both enzyme activities, produces a PAPS/APS ratio corresponding to a "channeling efficiency" of 96%. The velocity of the APS kinase reaction measured in the overall system with endogenously synthesized APS is 8-fold greater than that of the isolated kinase reaction using exogenous APS. Most conclusively, isotope dilution and enrichment experiments show that the APS intermediate does not equilibrate with APS in the bulk medium but remains largely bound in the rat enzyme system. In contrast, control experiments with a nonchanneled system containing a mixture of the sulfurylase and kinase isolated from Penicillium chrysogenum give the results expected for a nonchanneled pathway. These data indicate that APS is channeled between the active sites of ATP sulfurylase and APS kinase during the production of PAPS in rat chondrosarcoma.
Adenosine Phosphosulfate↗
Rat chondrosarcoma ATP sulfurylase and adenosine 5'-phosphosulfate kinase reside on a single bifunctional protein.
The sulfate-activation pathway consists of the sequential action of ATP sulfurylase (ATP: sulfate adenylyltransferase, EC 2.7.7.4) and adenosine 5'-phosphosulfate kinase ATP:adenylylsulfate 3'-phosphotransferase, EC 2.7.1.25). Both sulfurylase and kinase from rat chondrosarcoma were copurified through substrate affinity chromatography using stable analogs of APS (adenosine 5'-phosphosulfate) and PAPS (3'-phosphoadenosine 5'-phosphosulfate). A 56-kDa protein, containing both activities, was then purified to apparent homogeneity through reversed-phase chromatography and observed on denaturing polyacrylamide gels. The molecular mass of the native active unit containing both activities in the purified preparation corresponded to approximately 60 kDa by analytical gel filtration. Coincident binding and elution of ATP sulfurylase and APS kinase by immunoaffinity chromatography, using polyclonal serum generated against the 56-kDa protein, also demonstrated that the enzyme contains both activities. Lastly, a single N-terminal amino acid sequence was obtained from the 56-kDa band isolated by gel electrophoresis. These results all suggest that ATP sulfurylase and APS kinase from rat chondrosarcoma residue on a single bifunctional protein.
Amino Acid Sequence↗