Michael B. Sporn

Bio: Michael B. Sporn is an academic researcher from Dartmouth College. The author has contributed to research in topics: Transforming growth factor & Transforming growth factor beta. The author has an hindex of 157, co-authored 559 publications receiving 94605 citations. Previous affiliations of Michael B. Sporn include Cornell University & Reata Pharmaceuticals.

Transforming growth factor type beta induces monocyte chemotaxis and growth factor production

Abstract: Recent studies have focused on the potential role of transforming growth factor type beta (TGF-beta) as an immunoregulatory peptide. In this context, we demonstrate that TGF-beta is a potent chemoattractant for human peripheral blood monocytes. At concentrations from 0.1 to 10 pg/ml, TGF-beta induces directed monocyte migration in vitro. Consistent with this observation is the expression of high-affinity TGF-beta receptors on the monocytes with a Kd of 1-10 pM. At higher concentrations of TGF-beta (greater than or equal to 1 ng/ml), monocytes are stimulated to generate biologically active mediator(s) that enhance fibroblast growth. Gene expression for one of these growth factors, interleukin 1, is induced in monocytes within hours after exposure to TGF-beta. Thus, TGF-beta may provide an important signal for monocyte recruitment and for regulation of their synthesis of mediators of fibroblast growth and activity in wound healing.

Transforming growth factor-beta: biological function and chemical structure

Abstract: Transforming growth factor-beta (TGF-beta) is a multifunctional peptide that controls proliferation, differentiation, and other functions in many cell types. Many cells synthesize TGF-beta and essentially all of them have specific receptors for this peptide. TGF-beta regulates the actions of many other peptide growth factors and determines a positive or negative direction of their effects. Its marked ability to enhance formation of connective tissue in vivo suggests several therapeutic applications.

Peptide Growth Factors and Their Receptors

Abstract: This two-volume treatise, the collected effort of more than 50 international experts, represents the first comprehensive survey of the chemistry and biology of the set of molecules known as peptide growth factors. These substances are of universal importance in biology and medicine and are the basis of common language of intercellular communication.-The detailed description of each of the major peptide growth factors is the principal focus of these volumes. Essential information is provided on the primary structure, gene structure, gene regulation, cell surface receptors, biological activity, and potential therapeutic applications of each growth factor. The coordinate actions of sets of growth factors and their role in controlling fundamental processes that pertain to many different cells and tissues are also dealt with.-The peptides described here are of fundamental importance for understanding the behavior of all cells, and they will be of major importance in the practice of clinical medicine in the years to come.- These volumes will be of value to both researchers and clinicians in their pursuit and application of new knowledge in this promising area.

Transforming growth factor alpha: mutation of aspartic acid 47 and leucine 48 results in different biological activities.

Abstract: To study the relationship between the primary structure of transforming growth factor alpha (TGF-alpha) and some of its functional properties (competition with epidermal growth factor (EGF) for binding to the EGF receptor and induction of anchorage-independent growth), we introduced single amino acid mutations into the sequence for the fully processed, 50-amino-acid human TGF-alpha. The wild-type and mutant proteins were expressed in a vector by using a yeast alpha mating pheromone promoter. Mutations of two amino acids that are conserved in the family of the EGF-like peptides and are located in the carboxy-terminal part of TGF-alpha resulted in different biological effects. When aspartic acid 47 was mutated to alanine or asparagine, biological activity was retained; in contrast, substitutions of this residue with serine or glutamic acid generated mutants with reduced binding and colony-forming capacities. When leucine 48 was mutated to alanine, a complete loss of binding and colony-forming abilities resulted; mutation of leucine 48 to isoleucine or methionine resulted in very low activities. Our data suggest that these two adjacent conserved amino acids in positions 47 and 48 play different roles in defining the structure and/or biological activity of TGF-alpha and that the carboxy terminus of TGF-alpha is involved in interactions with cellular TGF-alpha receptors. The side chain of leucine 48 appears to be crucial either indirectly in determining the biologically active conformation of TGF-alpha or directly in the molecular recognition of TGF-alpha by its receptor.

Type beta transforming growth factor: a bifunctional regulator of cellular growth.

Abstract: Type beta transforming growth factor (TGF-beta) is a two-chain polypeptide of 25,000 daltons isolated from many tissues, including bovine kidney, human placenta, and human platelets. It has been characterized by its ability to stimulate reversible transformation of nonneoplastic murine fibroblasts, as measured by the formation of colonies of these cells in soft agar (ED50 = 4 pM TGF-beta for NRK fibroblasts). We now show that the response of cells to TGF-beta is bifunctional, in that TGF-beta inhibits the anchorage-dependent growth of NRK fibroblasts and of human tumor cells by increasing cell cycle time. Moreover, the anchorage-independent growth of many human melanoma, lung carcinoma, and breast carcinoma cell lines is inhibited by TGF-beta at concentrations in the same range as those that stimulate colony formation of NRK fibroblasts (average ED50 = 10-30 pM TGF-beta for inhibition). Whereas epidermal growth factor and TGF-beta synergize to induce anchorage-independent growth of NRK fibroblasts, their effects on the growth of A-549 human lung carcinoma cells are antagonistic. The bifunctional response of cells to TGF-beta is further demonstrated in Fischer rat 3T3 fibroblasts transfected with a cellular myc gene. In these cells TGF-beta synergizes with platelet-derived growth factor to stimulate colony formation but inhibits the colony formation induced by epidermal growth factor. The data indicate that the effects of TGF-beta on cells are not a function of the peptide itself, but rather of the total set of growth factors and their receptors that is operant in the cell at a given time.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The pathogenesis of atherosclerosis: a perspective for the 1990s

Abstract: Atherosclerosis, the principal cause of heart attack, stroke and gangrene of the extremities, is responsible for 50% of all mortality in the USA, Europe and Japan. The lesions result from an excessive, inflammatory-fibroproliferative response to various forms of insult to the endothelium and smooth muscle of the artery wall. A large number of growth factors, cytokines and vasoregulatory molecules participate in this process. Our ability to control the expression of genes encoding these molecules and to target specific cell types provides opportunities to develop new diagnostic and therapeutic agents to induce the regression of the lesions and, possibly, to prevent their formation.

TGF-beta signal transduction.

Abstract: The transforming growth factor beta (TGF-beta) family of growth factors control the development and homeostasis of most tissues in metazoan organisms. Work over the past few years has led to the elucidation of a TGF-beta signal transduction network. This network involves receptor serine/threonine kinases at the cell surface and their substrates, the SMAD proteins, which move into the nucleus, where they activate target gene transcription in association with DNA-binding partners. Distinct repertoires of receptors, SMAD proteins, and DNA-binding partners seemingly underlie, in a cell-specific manner, the multifunctional nature of TGF-beta and related factors. Mutations in these pathways are the cause of various forms of human cancer and developmental disorders.