Showing papers by "Michael B. Sporn published in 1993"
TL;DR: Pathological examination revealed an excessive inflammatory response with massive infiltration of lymphocytes and macrophages in many organs, but primarily in heart and lungs, which suggests a prominent role for TGF-beta 1 in homeostatic regulation of immune cell proliferation and extravasation into tissues.
Abstract: To delineate specific developmental roles of transforming growth factor beta 1 (TGF-beta 1) we have disrupted its cognate gene in mouse embryonic stem cells by homologous recombination to generate TGF-beta 1 null mice. These mice do not produce detectable amounts of either TGF-beta 1 RNA or protein. After normal growth for the first 2 weeks they develop a rapid wasting syndrome and die by 3-4 weeks of age. Pathological examination revealed an excessive inflammatory response with massive infiltration of lymphocytes and macrophages in many organs, but primarily in heart and lungs. Many lesions resembled those found in autoimmune disorders, graft-vs.-host disease, or certain viral diseases. This phenotype suggests a prominent role for TGF-beta 1 in homeostatic regulation of immune cell proliferation and extravasation into tissues.
1,923 citations
TL;DR: In vivo roles of TGF-β will be considered in the context of the inherent complexity of cell-matrix and cell-cell interactions characteristic of mixed cell populations, tissues, or organs.
Abstract: In the 10 years since its definition and characterization, TGF-β has come to be accepted as the prototypical multifunctional peptide growth factor. Attempts to understand its mechanism of action on cells have resulted in conceptual advances in knowledge of the contextual nature of growth factor activities. These have included modulatory effects both of sets of growth factors and of the cellular environment, including extracellular matrix (Sporn and Roberts, 1990; Nathan and Sporn, 1991). Because of the breadth of the cellular targets and activities of TGF-β it is impossible to be comprehensive in review of its physiological roles. Rather, we will cover selected aspects with emphasis on physiological roles which might ultimately find clinical application. As much as possible, we will consider in vivo roles of TGF-β in the context of the inherent complexity of cell-matrix and cell-cell interactions characteristic of mixed cell populations, tissues, or organs.
751 citations
TL;DR: It is proposed that one function of TGF-beta 1 during endochondral ossification is regulation of chondrocyte growth and differentiation through modulation of the relative expression of cartilage matrix proteins and metalloproteases.
244 citations
TL;DR: TGF- beta expression and function are compartmentalized in epidermis and epidermal tumors and that loss of TGF-beta is an early, biologically relevant risk factor for malignant progression is shown.
Abstract: Mouse skin carcinomas arise from a small subpopulation of benign papillomas with an increased risk of malignant conversion. These papillomas arise with limited stimulation by tumor promoters, appear rapidly, and do not regress, suggesting that they differ in growth properties from the majority of benign tumors. The transforming growth factor beta (TGF-beta) proteins are expressed in the epidermis and are growth inhibitors for mouse keratinocytes in vitro; altered TGF-beta expression could influence the growth properties of high-risk papillomas. Normal epidermis, tumor promoter-treated epidermis, and skin papillomas at low risk for malignant conversion express TGF-beta 1 in the basal cell compartment and TGF-beta 2 in the suprabasal strata. In low-risk tumors, 90% of the proliferating cells are confined to the basal compartment. In contrast, the majority of high-risk papillomas are devoid of both TGF-beta 1 and TGF-beta 2 as soon as they arise; these tumors have up to 40% of the proliferating cells in the suprabasal layers. Squamous cell carcinomas are also devoid of TGF-beta, suggesting that they arise from the TGF-beta-deficient high-risk papillomas. In some high-risk papillomas, TGF-beta 1 loss can occur first and correlates with basal cell hyperproliferation, while TGF-beta 2 loss correlates with suprabasal hyperproliferation. Similarly, TGF-beta 1-null transgenic mice, which express wild-type levels of TGF-beta 2 in epidermis but no TGF-beta 1 in the basal layer, have a hyperproliferative basal cell layer without suprabasal proliferation. In tumors, loss of TGF-beta is controlled at the posttranscriptional level and is associated with expression of keratin 13, a documented marker of malignant progression. These results show that TGF-beta expression and function are compartmentalized in epidermis and epidermal tumors and that loss of TGF-beta is an early, biologically relevant risk factor for malignant progression.
210 citations
TL;DR: Altered regulation of MHC expression may be a critical step leading to the multifocal inflammation and wasting syndrome seen in the TGF-beta 1 null mouse, and potential applications for T GF-beta in the management of autoimmune disease, allograft rejection, and other problems associated with altered MHCexpression are suggested.
Abstract: The phenotype of the transforming growth factor beta 1 (TGF-beta 1) null mouse has been previously described and is characterized by inflammatory infiltrates in multiple organs leading to a wasting syndrome and death as early as 3 weeks after birth. Since this phenotype occurs in the absence of any detectable pathogen, potential autoimmune disease mechanisms were investigated. We examined major histocompatibility complex (MHC) mRNA expression in tissues of the TGF-beta 1 null mouse and found levels of both the class I and class II MHC mRNA elevated compared to normal or TGF-beta 1 heterozygous littermates. This elevated expression was seen prior to any evidence of inflammatory infiltrates, suggesting a causal relationship between increased MHC expression and activation of immune cell populations. Cell surface expression of MHC molecules was detected by immunohistochemistry and correlated well with mRNA levels. Expression of mRNA for interferon gamma and its receptor was unchanged at the ages when increased MHC expression became apparent. Down-regulation of class I MHC expression by TGF-beta 1 was also demonstrated in vitro in fibroblasts isolated from TGF-beta 1 null mice. These findings suggest that one natural function of TGF-beta 1 is to control expression of both MHC classes. Altered regulation of MHC expression may be a critical step leading to the multifocal inflammation and wasting syndrome seen in the TGF-beta 1 null mouse. These results suggest potential applications for TGF-beta in the management of autoimmune disease, allograft rejection, and other problems associated with altered MHC expression.
175 citations
TL;DR: Findings raise the possibility that TGF‐β may co‐operate with other growth factors to control astrocyte proliferation in vivo.
Abstract: We have studied the influence of three members of the transforming growth factor-beta (TGF-beta) family of multifunctional growth factors on the proliferation of cultured astrocytes isolated from newborn mouse cerebral cortex. Although TGF-beta s 1, 2, and 3 cause only a small reduction in the low level of astrocyte proliferation occurring in chemically defined medium, they each inhibit the effects of five astrocyte mitogens (bFGF, EGF, PDGF, IL-1 alpha, and IL-2). Inhibition is observed when astrocytes are exposed to mitogen and TGF-beta at the same time and when they are exposed to TGF-beta prior to, and separately from, mitogen. This latter effect appears to be due to the binding of TGF-beta s to astrocyte-secreted extracellular matrix. These findings raise the possibility that TGF-beta may co-operate with other growth factors to control astrocyte proliferation in vivo.
101 citations
Journal Article•
TL;DR: While its mechanism of action in this system remains unclear, fenretinide is an effective agent for the chemoprevention and growth modulation of oncogene-induced prostate cancer in the mouse prostate reconstitution model system and may be effective for the Chemopreventions of human prostate cancer.
Abstract: Several epidemiological studies have implicated low dietary and serum levels of retinol with an increased risk for the development of human prostate cancer. In a recent report, dietary fenretinide [ N -[(4-hydroxyphenyl)] retinamide], a synthetic retinoid with low toxicity, decreased the incidence of experimentally induced prostate cancer. Fenretinide is currently being evaluated in phase I and phase II clinical trials as an agent for both the treatment and chemoprevention of human prostate cancer. Because of these findings, we investigated whether dietary fenretinide could alter the incidence or phenotype of oncogene-induced prostate cancer in the mouse prostate reconstitution model system. When compared to control-fed animals, dietary fenretinide reduced the tumor incidence by 49% and the tumor mass by 52% of ras+myc -induced cancers in the mouse prostate reconstitution model system, which was modified to prolong the latency period before cancer development. Retinoids have a wide ranging effect on cellular differentiation, growth factor synthesis, and immune function. While its mechanism of action in this system remains unclear, fenretinide is an effective agent for the chemoprevention and growth modulation of oncogene-induced prostate cancer in the mouse prostate reconstitution model system and may be effective for the chemoprevention of human prostate cancer.
96 citations
TL;DR: In this paper, a Drosophila melanogaster cell culture system was employed to examine expression levels of pTGF-β::cat constructs coexpressed with an Spl expression plasmid in a cell background devoid of any Spl homolog.
83 citations
70 citations
TL;DR: The structural characteristics observed for T GF-beta 1 in solution generally agree closely with the recently derived crystal structures of TGF-beta 2 and several noteworthy differences were observed that may be related to function.
Abstract: Virtually complete backbone NMR signal assignments have been reported for transforming growth factor @1 (TGF-@1) (Archer et al. (1993) Biochemistry (preceding paper in this issue)). Herein we report the secondary structure of the protein in solution on the basis of these assignments and proton NOE's observed in a variety of 2D and 3D heteronuclear NMR spectra. Regular elements of secondary structure derived from the NOE data consist of (a) three helices spanning residues Y58-H68, F24429, and N5-F8 and (b) several pairs of two-stranded antiparallel @-sheets. The longest two-stranded sheet runs from residue L83 to V106 with a type I1 reverse turn at G93-R94 and a chain twist at residue N103-M104. These elements of regular structure were confirmed by hydrogen exchange, chemical shift, and coupling constant data. With the exception of residues G46453, which exhibit relatively few and weak intraresidue NOE's, residues in the rest of the protein adopt an irregular but well-defined structure. All peptide bonds are trans except for a cis peptide bond between Glu35 and Pro36. The structural characteristics observed for TGF-@l in solution generally agree closely with the recently derived crystal structures of TGF-@2 (Daopin et al. (1992) Science 257,369-374; Schlunegger & Griitter (1992) Nature 358,4304341. Several noteworthy differences were observed that may be related to function.
60 citations
TL;DR: To the authors' knowledge, this is the first report of the use of an animal cell expression system to obtain extensive isotopic enrichment and resonance assignments of TGF-beta 1 in order to sequentially assign a protein.
Abstract: The transforming growth factor 8s are a homologous family of multifunctional cytokines that regulate cell growth and differentiation. As a prelude to studies of the solution structure and dynamics of TGF-81, we report virtually complete assignment of 'H and 15N resonances for this 25-kDa homodimeric protein. Recombinant TGF-81 was expressed in Chinese hamster ovary cells. The cells were grown either in a completely 15N-enriched medium or in a medium containing selectively 13C,15N-labeled amino acids to obtain either uniformly or specifically labeled protein, respectively. Two- and three-dimensional heteronuclear edited magnetic resonance spectra of the uniformly 15N-labeled protein and three samples selectively labeled with 13C and 15N yielded assignments for 96% of the backbone amide and Ca protons and 87% of the side chain protons. To our knowledge, this is the first report of the use of an animal cell expression system to obtain extensive isotopic enrichment in order to sequentially assign a protein. The methodology described herein for the isotopic enrichment and resonance assignments of TGF-81 should be generally applicable to other eukaryotic proteins expressed by animal cells. The transforming growth factor Bs (TGF-Ps)' are important regulators of numerous physiological processes including normal tissue growth and wound repair (Roberts & Sporn, 1990; Sporn & Roberts, 1990; Massagub, 1990). The diverse activities of these proteins include their ability to act as multifunctional regulators of the growth and differentiation of many types of cells. The TGF-Bs are important in maintenance of normal epithelial structures, in the formation and repair of connective tissue and bone, and in the formation and function of the cells of the blood and the immune system. TGF-@s and their receptors are present in nearly all cells. Five homologous forms of TGF-19 have been characterized, two of which have been isolated from natural sources in significant quantities: TGF-01 and TGF-82. TGF-B1 was originally isolated from human platelets but also has been purified from additional sources including bovine kidney, bovine bone, and porcine platelets. Recently, TGF-B1 has been cloned and
TL;DR: Two distinct functional domains of TGF-beta are identified involved in determining the biological potencies and functions of the molecule and are important for determining the potency of T GF-beta to inhibit growth of the LS513 human colorectal cancer cell line.
Abstract: Three distinct isoforms of transforming growth factor beta (TGF-beta) are expressed in mammalian cells. Although many cells respond equivalently to all three isoforms, certain cells respond selectively. Using chimeric proteins in which selected regions of the different isoforms were interchanged, we have identified two distinct functional domains of TGF-beta involved in determining the biological potencies and functions of the molecule. The first domain is important for determining whether TGF-beta can be sequestered by alpha 2-macroglobulin. By replacing aa 45 and 47 of TGF-beta 2 with the corresponding amino acids of TGF-beta 1, sequestration of the TGF-beta molecule by alpha 2-macroglobulin was markedly reduced. The second domain is functionally different from the alpha 2-macroglobulin sequestration site and is important for determining the potency of TGF-beta to inhibit growth of the LS513 human colorectal cancer cell line. Neither the TGF-beta 2/beta 1-(40-47) replacement construct nor a chimera containing aa 1-39 of TGF-beta 2, aa 40-82 of TGF-beta 1, and aa 83-112 of TGF-beta 2 was equivalent to TGF-beta 1 in inhibiting growth of LS513 cells. This fact suggests that additional amino acids outside of the aa 40-82 region are required to specify TGF-beta 1 activity with these cells.
Journal Article•
TL;DR: High levels of SGP-2 expression are found in the epithelial component of carcinomas of the prostate and seminal vesicle after initiation with N-nitroso-N-methylurea and promotion with testosterone propionate.
Abstract: To understand the molecular mechanism of carcinogenesis in androgen-dependent tumors, we have searched for new markers which are associated with this process. In normal rat prostate and seminal vesicle, sulfated glycoprotein 2 (SGP-2) messenger RNA is barely detectable. However, we have found high levels of SGP-2 expression in the epithelial component of carcinomas of the prostate and seminal vesicle after initiation with N-nitroso-N-methylurea and promotion with testosterone propionate. We have also observed induction of SGP-2 expression in epithelial cells at early stages in carcinogenesis when cytologically malignant cells first begin to appear. SGP-2 has been reported previously to be associated with a variety of models of programmed cell death (apoptosis), including the prostate following castration. Our present findings provide a novel marker for carcinogenesis in the rat prostate and seminal vesicle.
TL;DR: The increase in TGF-beta s after hyperthermia could play a role in mediating the reported cardioprotective effects of heat shock, as well as in the heart in vivo.
Abstract: Hyperthermia causes changes in expression of TGF-beta mRNA and protein in cultured cardiac cells, as well as in the heart in vivo. 12 h after hyperthermia, primary cultures of neonatal rat cardiomyocytes show a two- to threefold decreased expression of TGF-beta mRNAs which returns to control levels by 48 h after heat shock. In cultures of cardiac fibroblasts, expression of TGF-beta mRNAs increases 5-25-fold, 12-48 h after heat shock, while fetal bovine heart endothelial cells show little change in TGF-beta expression after hyperthermia. In each case, mRNAs for TGF-beta s 1, 2, and 3 are regulated similarly. Hearts isolated from rats exposed to hyperthermia show an initial 20-fold decrease in TGF-beta 1 and 3 mRNA levels which return to control levels by 24 h and subsequently are elevated two- to threefold above normal 48-72 h after heat shock; there is little change in TGF-beta 2 mRNA. Expression of immunoreactive TGF-beta 1 and 3 protein, localized intracellularly in myocytes, follows the same pattern as the mRNA expression. By 72 h, some myocytes show hyperstaining for TGF-beta 1. Staining for extracellular TGF-beta 1/3 exhibits the opposite time course, being most intense 3-6 h after heat shock and returning to control levels by 48 h. The increase in TGF-beta s after hyperthermia could play a role in mediating the reported cardioprotective effects of heat shock.
Journal Article•
TL;DR: The results suggest different roles for TGF-betas 1 and 3 in neuroblastoma and rhabdomyosarcoma, in contrast to previous work which suggested these proteins may promote the growth of rhabDomyosARcoma by suppressing differentiation.
Abstract: The transforming growth factor (TGF)-betas are a highly conserved group of potent multifunctional cell regulatory proteins with variable effects on cell growth and differentiation Most of the small round cell group of childhood tumors are thought to arise from either primitive mesenchyme or neuroectoderm and show evidence of skeletal muscle or neural differentiation, and rarely both To investigate the possibility that the TGF-betas have a role in the growth or differentiation of these neoplasms, we used antibodies specific for peptide sequences of the three known mammalian TGF-beta isoforms (TGF-betas 1, 2, and 3) to probe for TGF-beta protein expression in a total of 49 cases TGF-beta 1 immunoreactivity was present in 16/17 (94%) of rhabdomyosarcomas, and the staining intensity was usually strong TGF-beta 1 was also present in three of three ectomesenchymomas In contrast, TGF-beta 1 was absent in all but one out of nine poorly differentiated neuroblastomas Differentiating neuronal cells of ganglioneuroblastomas, however, were strongly positive for TGF-beta 1 Ewing's sarcomas and peripheral primitive neuroectodermal tumors had a less consistent, but usually positive, staining pattern TGF-beta 3 staining patterns were very similar to those of TGF-beta 1 TGF-beta 2 immunoreactivity was only rarely detected in this group of tumors The results suggest different roles for TGF-betas 1 and 3 in neuroblastoma and rhabdomyosarcoma Expression of TGF-betas 1 and 3 is associated with neuronal differentiation of neuroblastoma In contrast, these proteins may promote the growth of rhabdomyosarcoma by suppressing differentiation
TL;DR: Data suggest that TGF-β will be useful clinically in treatment of both reperfusion injury and inflammatory diseases of the heart.
TL;DR: The results of investigations directed at elucidating the role of TGF-s are discussed, with emphasis on its localization in the adult myocardium, its possible function in maintaining the rhythmic, contractile nature of cardiac tissue, and its role in response of the heart to injury and to ischemia.
Abstract: Recently it has become appreciated that the myocardium produces several growth factors (cytokines) and that their expression is highly regulated not only in development but also in injury and disease [1]. One of these cytokines, transforming growth factor-s (TGF-s), a dimeric, multifunctional peptide [2], is expressed at high levels in the heart during both embryonic and adult life [3,4]. In this brief review, we will discuss the results of investigations directed at elucidating the role of TGF-s in the heart with emphasis on its localization in the adult myocardium, its possible function in maintaining the rhythmic, contractile nature of cardiac tissue, and its role in response of the heart to injury and to ischemia.