IRAK (Pelle) family member IRAK-2 and MyD88 as proximal mediators of IL-1 signaling

The interleukin-1 receptor (IL-1R) signaling pathway leads to nuclear factor kappa B (NF-kappaB) activation in mammals and is similar to the Toll pathway in Drosophila: the IL-1R-associated kinase (IRAK) is homologous to Pelle. Two additional proximal mediators were identified that are required for IL-1R-induced NF-kappaB activation: IRAK-2, a Pelle family member, and MyD88, a death domain-containing adapter molecule. Both associate with the IL-1R signaling complex. Dominant negative forms of either attenuate IL-1R-mediated NF-kappaB activation. Therefore, IRAK-2 and MyD88 may provide additional therapeutic targets for inhibiting IL-1-induced inflammation.

BLyS: member of the tumor necrosis factor family and B lymphocyte stimulator

The tumor necrosis factor (TNF) superfamily of cytokines includes both soluble and membrane-bound proteins that regulate immune responses. A member of the human TNF family, BLyS (B lymphocyte stimulator), was identified that induced B cell proliferation and immunoglobulin secretion. BLyS expression on human monocytes could be up-regulated by interferon-gamma. Soluble BLyS functioned as a potent B cell growth factor in costimulation assays. Administration of soluble recombinant BLyS to mice disrupted splenic B and T cell zones and resulted in elevated serum immunoglobulin concentrations. The B cell tropism of BLyS is consistent with its receptor expression on B-lineage cells. The biological profile of BLyS suggests it is involved in monocyte-driven B cell activation.

Hierarchically ordered oxides

Porous silica, niobia, and titania with three-dimensional structures patterned over multiple length scales were prepared by combining micromolding, polystyrene sphere templating, and cooperative assembly of inorganic sol-gel species with amphiphilic triblock copolymers. The resulting materials show hierarchical ordering over several discrete and tunable length scales ranging from 10 nanometers to several micrometers. The respective ordered structures can be independently modified by choosing different mold patterns, latex spheres, and block copolymers. The examples presented demonstrate the compositional and structural diversities that are possible with this simple approach.

Synthesis and release of B-lymphocyte stimulator from myeloid cells

B-lymphocyte stimulator (BLyS) is a recently identified novel member of the tumor necrosis factor ligand superfamily shown to exist in a membrane-bound and soluble form. BLyS was found to be specifically expressed on cells of myeloid lineage and to selectively stimulate B-lymphocyte proliferation and immunoglobulin production. The expression of a cytokine involved in potentiation of humoral immune responses, such as BLyS, is expected to be strictly controlled. The goal of the present study was to examine regulation of BLyS levels in monocytic cells in response to cytokines and during their differentiation to macrophages and dendritic cells. The presence of BLyS on the cell surface and in the culture medium of both normal blood monocytes and on tumor cells of myelomonocytic origin was demonstrated. BLyS gene expression and levels of membrane-associated and soluble BLyS were found to be regulated by cytokines, in particular interferon (IFN)-gamma and to a lesser extent interleukin-10 (IL-10). The expression of BLyS on monocyte membranes was retained following differentiation into macrophages, but detection on the surface of monocyte-derived dendritic cells required stimulation with IFN-gamma. Both IFN-gamma and IL-10 enhanced the release of soluble BLyS that was active in B-cell proliferation assays. Cells transfected with BLyS complementary DNA mutated in a predicted cleavage site failed to release BLyS into the culture medium, thereby suggesting that soluble BLyS was derived from the membrane form. These results provide further support for an important role for BLyS expressed in myeloid cells in B-cell expansion and antibody responses.

Simultaneous identification of strains of Escherichia coli serotype O157:H7 and their Shiga-like toxin type by mismatch amplification mutation assay-multiplex PCR

Mismatch amplification mutation assay primers, specific for a unique base substitution in uidA of Escherichia coli O157:H7, was coupled with primers for the Shiga-like toxin I (SLT-I) and SLT-II genes in a multiplex PCR assay. Analysis of 108 bacteria showed that all Escherichia coli serotype O157:H7 strains were identified simultaneously with the SLT types encoded by these strains.

Genotypic and phenotypic changes in the emergence of Escherichia coli O157:H7

Escherichia coli O157:H7 is a foodborne pathogen distinguished from typical E. coli by the production of Shiga toxins (Stx) and the inability to ferment sorbitol (SOR) and to express beta-glucuronidase (GUD) activity. An allele-specific probe for the GUD gene (uidA) and multilocus enzyme electrophoresis were used to elucidate stages in the evolutionary emergence of E. coli O157: H7. A point mutation at +92 in uidA was found only in O157:H7 and its nonmotile relatives, including a SOR+ O157:H clone implicated in outbreaks of hemolytic-uremic syndrome in Germany. The results support a model in which O157:H7 evolved sequentially from an O55:H7 ancestor, first by acquiring the Stx2 gene and then by diverging into two branches; one became GUD- SOR- , resulting in the O157:H7 clone that spread worldwide, and the other lost motility, leading to the O157:H clone that is an increasing public health problem in Europe.

Rapid detection of food-borne pathogenic bacteria

Recent advancements in biotechnology are rapidly altering the diagnostic procedures used in microbiologic analysis of foods. Biochemical identification tests have been miniaturized and automated, making them faster and more economical. Pathogenic bacteria that were previously isolated and identified after labor- and time-intensive enrichment and plating procedures can now be detected by measuring specific physicochemical changes resulting from their growth or metabolic activity. Nucleic acid and antibody-based assays are now used to rapidly and reliably detect pathogenic bacteria in foods. Nevertheless, foods offer unique challenges to the application of these techniques because of their complexity and variety, their interference with the rapid detection methods, and the need to detect pathogenic bacteria when they are present in foods at very low levels. Methods to sequester target pathogenic bacteria from interfering food components and to concentrate them in small volumes are needed to enable the efficient application of rapid detection and identification methods.

Interferon-kappa, a novel type I interferon expressed in human keratinocytes

High throughput cDNA sequencing has led to the identification of interferon-kappa, a novel subclass of type I interferon that displays approximately 30% homology to other family members. Interferon-kappa consists of 207 amino acids, including a 27-amino acid signal peptide and a series of cysteines conserved in type I interferons. The gene encoding interferon-kappa is located on the short arm of chromosome 9 adjacent to the type I interferon gene cluster and is selectively expressed in epidermal keratinocytes. Expression of interferon-kappa is significantly enhanced in keratinocytes upon viral infection, upon exposure to double-stranded RNA, or upon treatment with either interferon-gamma or interferon-beta. Administration of interferon-kappa recombinant protein imparts cellular protection against viral infection in a species-specific manner. Interferon-kappa activates the interferon-stimulated response element signaling pathway and a panel of genes similar to those regulated by other type I interferons including anti-viral mediators and transcriptional regulators. An antibody that neutralizes the type I interferon receptor completely blocks interferon-kappa signaling, demonstrating that interferon-kappa utilizes the same receptor as other type I interferons. Interferon-kappa therefore defines a novel subclass of type I interferon that is expressed in keratinocytes and expands the repertoire of known proteins mediating host defense.

Tumor necrosis factor (TNF) receptor superfamily member TACI is a high affinity receptor for TNF family members APRIL and BLyS

An expression cloning approach was employed to identify the receptor for B-lymphocyte stimulator (BLyS) and identified the tumor necrosis factor receptor superfamily member TACI as a BLyS-binding protein. Expression of TACI in HEK293T cells confers on the cells the ability to bind BLyS with subnanomolar affinity. Furthermore, a TACI-Fc fusion protein recognizes both the cleaved, soluble form of BLyS as well as the membrane BLyS present on the cell surface of a recombinant cell line. TACI mRNA is found predominantly in B-cells and correlates with BLyS binding in a panel of B-cell lines. We also demonstrate that TACI interacts with nanomolar affinity with the BLyS-related tumor necrosis factor homologue APRIL for which no clear in vivo role has been described. BLyS and APRIL are capable of signaling through TACI to mediate NF-kappaB responses in HEK293 cells. We conclude that TACI is a receptor for BLyS and APRIL and discuss the implications for B-cell biology.

Large-cage zeolite structures with multidimensional 12-ring channels

Zeolite type structures with large cages interconnected by multidimensional 12-ring (rings of 12 tetrahedrally coordinated atoms) channels have been synthesized; more than a dozen large-pore materials were created in three different topologies with aluminum (or gallium), cobalt (or manganese, magnesium, or zinc), and phosphorus at the tetrahedral coordination sites. Tetragonal UCSB-8 has an unusually large cage built from 64 tetrahedral atoms and connected by an orthogonal channel system with 12-ring apertures in two dimensions and 8-ring apertures in the third. Rhombohedral UCSB-10 and hexagonal UCSB-6 are structurally related to faujasite and its hexagonal polymorph, respectively, and have large cages connected by 12-ring channels in all three dimensions.

Molecular characterization of the gene encoding H antigen in Escherichia coli and development of a PCR-restriction fragment length polymorphism test for identification of E. coli O157:H7 and O157:NM

Recent outbreaks of disease caused by Escherichia coli O157:H7 have focused much attention on this newly emerged pathogen. Identification of the H7 flagellar antigen is critical for the confirmation of E. coli O157:H7; however, clinical isolates are frequently nonmotile and do not produce detectable H antigen. To further characterize nonmotile isolates (designated NM), we developed a PCR-restriction fragment length polymorphism (PCR-RFLP) test to identify and characterize the gene encoding the H antigen (fliC) in E. coli. The entire coding sequence of fliC was amplified by PCR, the amplicon was restricted with RsaI, and the restriction fragment pattern was examined after gel electrophoresis. Two hundred eighty E. coli isolates representing serotypes O157:H7 and O157:NM, flagellar antigen H7 groups associated with other O serogroups, and all other flagellar antigen groups were analyzed. A single restriction pattern (pattern A) was identified for O157:H7 isolates, O157:NM isolates that produced Shiga toxin (formerly Shiga-like toxin or verotoxin), and 16 of 18 O55:H7 isolates. Flagellar antigen group H7 isolates of non-O157 serotypes had one of three banding patterns distinct from pattern A. A wide variety of patterns were found among isolates of the other 52 flagellar antigen groups; however, none was identical to the O157:H7 pattern. Thirteen of 15 nonmotile strains that did not produce the A pattern had patterns that matched those of other known H groups. The PCR-RFLP in conjunction with O serogroup determination will be useful in identifying E. coli O157:H7 and related strains that do not express immunoreactive H antigen and could be expanded to include other clinically important E. coli strains.

Role of zinc in the pathogenesis and treatment of prostate cancer: critical issues to resolve

The most consistent and persistent biochemical characteristic of prostate cancer (PCa) is the marked decrease in zinc and citrate levels in the malignant cells. This relationship provides compelling evidence that the lost ability of the malignant cells to accumulate zinc is an important factor in the development and progression of prostate malignancy. In addition, this relationship provides a rational basis for the concept that restoration of high zinc levels in malignant cells could be efficacious in the treatment and prevention of PCa. Epidemiological studies regarding dietary zinc effects on PCa have been conflicting and confusing. The purpose of this presentation is to present a current state of information regarding zinc relationships in the pathogenesis and treatment of PCa. We also hope to bring more attention to the medical and research community of the critical need for concerted clinical and basic research regarding zinc and PCa.

Polymerase chain reaction identification of Vibrio vulnificus in artificially contaminated oysters

DNAs extracted from Vibrio vulnificus seeded into oyster homogenates were evaluated as templates for the polymerase chain reaction. Several extraction procedures were examined, and it was determined that DNA recovered from cells lysed by guanidine isothiocyanate, extracted with chloroform, and precipitated with ethanol was most suitable for use as a polymerase chain reaction template. The region targeted was a 519-bp portion of the cytotoxin-hemolysin gene of V. vulnificus. This region was amplified only when DNA from this species was present in the homogenate. V. vulnificus seeded into oyster homogenates at an initial level of 10(2) CFU/g of oyster meat was consistently observed after 24 h of incubation in alkaline peptone water.

Structure of the NGFI-A gene and detection of upstream sequences responsible for its transcriptional induction by nerve growth factor

The NGFI-A gene encodes a "zinc-finger" protein that is rapidly induced by nerve growth factor (NGF) in PC12 rat pheochromocytoma cells. The complete exon/intron organization and nucleotide sequence of the rat NGFI-A gene have been determined. The gene spans 3789 nucleotides (nt) and is interrupted by a single intron at nt 588. All three zinc-finger DNA-binding domains are contiguously coded for within the 3' exon; this is in contrast to the structure described by others for the Xenopus laevis transcription factor TFIIIA gene. To analyze the transcription of this gene, we have determined the transcription start site and nucleotide sequence of the 5' flanking region. Transfection of PC12 cells with a fragment from the 5' flanking region linked to the chloramphenicol acetyltransferase (CAT) gene revealed that it contains an element which imparts an NGF-inducible phenotype to the normally silent CAT gene. Several regions with homologies to recognizable sequence elements are present in this fragment, including a TATA box at nt -27, serum response elements at nt -84, -106, -370, and -408, a cAMP-responsive element at nt -140, and a transcription factor Sp1-binding site at nt -286. These results establish the genomic structure of this mammalian multifinger protein and demonstrate that an NGF-responsive element lies upstream of the NGFI-A gene.

Human ZIP1 is a major zinc uptake transporter for the accumulation of zinc in prostate cells

The prostate gland of humans and other animals accumulates a level of zinc that is 3-10 times greater than that found in other tissues. Associated with this ability to accumulate zinc is a rapid zinc uptake process in human prostate cells, which we previously identified as the hZIP1 zinc transporter. We now provide additional evidence that hZIP1 is an important operational transporter that allows for the transport and accumulation of zinc. The studies reveal that hZIP1 (SLC39A1) but not hZIP2 (SLC39A2) is expressed in the zinc-accumulating human prostate cell lines, LNCaP and PC-3. Transfected PC-3 cells that overexpress hZIP1 exhibit increased uptake and accumulation of zinc. The V(max) for zinc uptake was increased with no change in K(m). Along with the increased intracellular accumulation of zinc, the overexpression of hZIP1 also results in the inhibition of growth of PC-3 cells. Down-regulation of hZIP1 by treatment of PC-3 cells with hZIP1 antisense oligonucleotide resulted in a decreased zinc uptake. Uptake of zinc from zinc chelated with citrate was as rapid as from free zinc ions; however, the cells did not take up zinc chelated with EDTA. The cellular uptake of zinc is not dependent upon an available pool of free Zn(2+) ions. Instead, the mechanism of transport appears to involve the transport of zinc from low molecular weight ligands that exist in circulation as relatively loosely bound complexes with zinc.

Escherichia coli serotype O157:H7: novel vehicles of infection and emergence of phenotypic variants

Escherichia coli serotype O157:H7 was only recognized as a human pathogen a little more than a decade ago, yet it has become a major foodborne pathogen. In the United States, the severity of serotype O157:H7 infections in the young and the elderly has had a tremendous impact on human health, the food industry, and federal regulations regarding food safety. The implication of acidic foods as vehicles of infection has dispelled the concept that low-pH foods are safe. Further, the association of nonbovine products with outbreaks suggests that other vehicles of transmission may exist for this pathogen. In laboratory diagnosis, most microbiologic assays rely on a single phenotype to selectively isolate this pathogen. However, the increasing evidence that phenotypic variations exist among isolates in this serogroup may eventually necessitate modifications in assay procedures to detect them.

Transforming growth factor-beta stimulates meiotic maturation of the rat oocyte

The effect of transforming growth factor-beta (TGF beta) on meiotic maturation was analyzed in oocytes from immature rats treated with PMSG. TGF beta accelerated the maturation of both follicle-enclosed oocytes and cumulus-oocyte complexes, as measured by an increase in the percentage of oocytes with germinal vesicle breakdown. Concentrations of the growth factor as low as 1 pM (25 pg/ml) increased oocyte maturation by 50% above control values, and 100 pM TGF beta caused a maximal 2-fold rise in the maturation rate. Germinal vesicle breakdown was significantly increased by TGF beta during the first 4 h of incubation, and stimulatory effects were observed as early as 1 h. However, by 8 h over 90% of the oocytes showed maturation in the absence or presence of TGF beta, indicating that the growth factor enhanced the spontaneous rate of oocyte development. TGF beta had no effect in denuded oocytes, demonstrating that the growth factor altered maturation through an action on the surrounding cumulus cells. Oocyte maturation was not accelerated by TGF beta in the presence of inhibitors of germinal vesicle breakdown, such as cAMP and hypoxanthine. Other growth factors, including IGF-I (50 ng/ml) and IGF-II (50 ng/ml), also stimulated oocyte maturation, while platelet-derived growth factor (100 ng/ml) and insulin (1 microgram/ml) had minimal effects on germinal vesicle breakdown. Although epidermal growth factor (EGF; 100 ng/ml) also increased the maturation of oocytes, lower concentrations of TGF beta (1-10 pM) suppressed EGF action by up to 30%. TGF beta, EGF, and insulin-like growth factors had minimal effects on cAMP production by cumulus-oocyte complexes. These results demonstrate that TGF beta and other growth factors are potent in vitro stimulators of oocyte maturation in the rat. Such effects of growth factors in vivo, in the presence of endogenous follicular factors and gonadotropic hormones, may regulate the selection and meiotic maturation of oocytes during follicular development. The rapidity of growth factor action in the oocyte provides a defined model to study signal transduction pathways of growth factors in relationship to their biological activity.

Extracellular matrix protein 1 (ECM1) has angiogenic properties and is expressed by breast tumor cells

Tumor growth and metastasis are critically dependent on the formation of new blood vessels. The present study found that extracellular matrix protein 1 (ECM1), a newly described secretory glycoprotein, promotes angiogenesis. This was initially suggested by in situ hybridization studies of mouse embryos indicating that the ECM1 message was associated with blood vessels and its expression pattern was similar to that of flk-1, a recognized marker for endothelium. More direct evidence for the role of ECM1 in angiogenesis was provided by the fact that highly purified recombinant ECM1 stimulated the proliferation of cultured endothelial cells and promoted blood vessel formation in the chorioallantoic membrane of chicken embryos. Immunohistochemical staining with specific antibodies indicated that ECM1 was expressed by the human breast cancer cell lines MDA-435 and LCC15, both of which are highly tumorigenic. In addition, staining of tissue sections from patients with breast cancer revealed that ECM1 was present in a significant proportion of primary and secondary tumors. Collectively, the results of this study suggest that ECM1 possesses angiogenic properties that may promote tumor progression.

mRNA decay during herpesvirus infections: interaction between a putative viral nuclease and a cellular translation factor

During lytic infections, the virion host shutoff (Vhs) protein (UL41) of herpes simplex virus destabilizes both host and viral mRNAs. By accelerating mRNA decay, it helps determine the levels and kinetics of viral and cellular gene expression. In vivo, Vhs shows a strong preference for mRNAs, as opposed to non-mRNAs, and degrades the 5' end of mRNAs prior to the 3' end. In contrast, partially purified Vhs is not restricted to mRNAs and causes cleavage of target RNAs at various sites throughout the molecule. To explain this discrepancy, we searched for cellular proteins that interact with Vhs using the Saccharomyces cerevisiae two-hybrid system. Vhs was found to interact with the human translation initiation factor, eIF4H. This interaction was verified by glutathione S-transferase pull-down experiments and by coimmunoprecipitation of Vhs and epitope-tagged eIF4H from extracts of mammalian cells. The interaction was abolished by several point mutations in Vhs that abrogate its ability to degrade mRNAs in vivo. The results suggest that Vhs is a viral mRNA degradation factor that is targeted to mRNAs, and to regions of translation initiation, through an interaction with eIF4H.

Novel taxa of thermally dimorphic systemic pathogens in the Ajellomycetaceae (Onygenales)

Recent discoveries of novel systemic fungal pathogens with thermally dimorphic yeast-like phases have challenged the current taxonomy of the Ajellomycetaceae, a family currently comprising the genera Blastomyces, Emmonsia, Emmonsiellopsis, Helicocarpus, Histoplasma, Lacazia and Paracoccidioides. Our morphological, phylogenetic and phylogenomic analyses demonstrated species relationships and their specific phenotypes, clarified generic boundaries and provided the first annotated genome assemblies to support the description of two new species. A new genus, Emergomyces, accommodates Emmonsia pasteuriana as type species, and the new species Emergomyces africanus, the aetiological agent of case series of disseminated infections in South Africa. Both species produce small yeast cells that bud at a narrow base at 37°C and lack adiaspores, classically associated with the genus Emmonsia. Another novel dimorphic pathogen, producing broad-based budding cells at 37°C and occurring outside North America, proved to belong to the genus Blastomyces, and is described as Blastomyces percursus.

Modulation of T-cell responses to alloantigens by TR6/DcR3

TR6 (DcR3) is a new member of the TNF receptor (TNFR) family that lacks a transmembrane domain in its sequence, indicating that it is a secreted molecule. TR6 can bind to FasL and prevent FasL-induced apoptosis; it can also associate with LIGHT, another TNF family member. The role of TR6 in immune responses was investigated in this study. According to flow cytometry, recombinant human TR6-Fc binds to human LIGHT expressed on 293 cells or on activated human T cells and competes with the LIGHT receptor TR2 for the binding to LIGHT on these cells. Human TR6 could cross-react with mouse LIGHT in immunoprecipitation. TR6-Fc also downregulates cytotoxic T lymphocyte activity in vitro and graft-versus-host responses in mice. Moreover, TR6-Fc modulates lymphokine production by alloantigen-stimulated mouse T cells. TR6-Fc ameliorated rejection response to mouse heart allograft. These results indicate that TR6 can dampen T-cell responses to alloantigens. Such regulatory effects of TR6 probably occur via interference with interaction between pairs of related TNF and TNFR family members, LIGHT/TR2 being one of the possible candidate pairs.

N-acetylation phenotype and genotype and risk of bladder cancer in benzidine-exposed workers

Several studies in subjects occupationally exposed to arylamine carcinogens have shown increased risks for bladder cancer associated with the slow acetylator phenotype. To follow up these reports, a case-control study of N-acetylation and bladder cancer risk was carried out among subjects occupationally exposed to benzidine, in benzidine dye production and use facilities in China. Thirty-eight bladder cancer cases and 43 controls from these factories were included for study of acetylation phenotype, by dapsone administration, and for polymorphisms in the NAT2 gene, by a polymerase chain reaction (PCR)-based test. In contrast to previous studies, no increase in bladder cancer risk was found for the slow N-acetylation phenotype (OR = 0.3; 95% CI = 0.1-1.3) or for slow N-acetylation-associated double mutations in NAT2 (OR = 0.5; 95% CI = 0.1-1.8). Examination of specific mutations and adjustment for age, weight, city and tobacco use did not alter the results. When examined by level of benzidine exposure in the cases, the bladder cancer risks associated with low (OR = 0.3, 95% CI = 0.0-2.2), medium (OR = 0.7, 95% CI = 0.1-4.5) and high (OR = 0.6, 95% CI = 0.1-3.5) exposure showed no interaction between genotype and benzidine exposure, within the range of exposures experienced by subjects in this study. This study, which is the first to incorporate phenotypic and genotypic analyses, provides evidence that the NAT2-related slow N-acetylation polymorphism is not associated with an increased risk of bladder cancer in workers exposed to benzidine, and may have a protective effect.

Hormonal control of epidermal growth factor receptors by gonadotropins during granulosa cell differentiation

The hormonal induction of epidermal growth factor (EGF) receptor formation was analyzed during the maturation of granulosa cells obtained from diethylstilbestrol-implanted immature rats. In the absence of FSH, EGF receptors (as measured by the binding of [125I]iodo-EGF to the intact cells) rose by 50% at 6 h of culture, but then declined to about 25-40% of their initial levels at 24-96 h of culture. Scatchard analyses demonstrated the presence of high affinity EGF-binding sites in both freshly prepared cells and after FSH treatment. FSH stimulated a dose-dependent increase in the EGF receptor content of granulosa cells during a 96-h culture period. Concentrations of FSH as low as 2.5-5 ng/ml elevated EGF receptor levels 2- to 3-fold compared to those in untreated control cells, and 30 ng/ml FSH caused a maximal 15-fold rise. FSH increased EGF receptor levels approximately 2-fold in the first 6 h of culture and by up to 7-fold at 96 h compared to levels in freshly prepared cells. FSH treatment did not change the binding affinity (Kd = 5-6 X 10(-11) M) of the EGF receptor, but increased the total number of EGF-binding sites. The stimulatory effects of FSH on EGF receptor expression were mimicked by other cAMP-inducing ligands, including 8-bromo-cAMP, forskolin, and choleragen. Ligands known to inhibit granulosa cell function, including GnRH agonists and the phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate, reduced the stimulation of EGF receptors by FSH. However, only 12-O-tetradecanoyl-phorbol 13-acetate suppressed the induction of EGF receptors by 8-bromo-cAMP. In granulosa cells cultured for 48 h with FSH, subsequent treatment with hCG for 24 h reduced EGF receptor content by 25%. Autoradiographic studies with [125I]iodo-EGF in ovarian thin sections demonstrated that EGF-binding sites were uniformly dispersed throughout the ovaries of diethylstilbestrol-implanted rats. Treatment with PMSG markedly increased EGF receptors in the outer walls of the growing follicles, while hCG treatment after PMSG caused a general decline in ovarian labeling. These results indicate that FSH maintains and increases the number of EGF receptors during granulosa cell differentiation, while LH/hCG reduces EGF-binding sites. Such changes in EGF receptors in the presence of endogenous growth factors may influence the number and selection of follicles destined for ovulation.

The human extracellular matrix gene 1 (ECM1): genomic structure, cDNA cloning, expression pattern, and chromosomal localization

The Ecm1 gene encodes an 85-kDa protein of unknown function that was originally identified as a secretory protein of the murine osteogenic stromal cell line MN7. This paper describes the isolation of a genomic clone containing the human ECM1 gene from a chromosome 1 cosmid library and the characterization of its exon-intron structure. The protein coding region comprises 10 exons. The ECM1 gene maps at chromosome 1q21 outside the epidermal differentiation complex region. The ECM1 gene appears to be expressed as a 1.8-kb transcript predominantly in placenta and heart, while an additional 1.4-kb alternatively spliced message was detected in tonsils. The full-length human ECM1 transcript contains 1838 bp and has an overall homology of 79.6% with the mouse Ecm1 cDNA. This transcript codes for a protein of 540 amino acids that is 69.4% identical and 81.3% similar to the corresponding mouse protein. The alternatively spliced variant, 1450 bp long, encodes a protein of 415 amino acids.