Melanie E. DeFord

Characterization of kringle domains of angiostatin as antagonists of endothelial cell migration, an important process in angiogenesis.

Angiogenesis is a complex process that involves endothelial cell proliferation, migration, basement membrane degradation, and neovessel organization. Angiostatin, consisting of four homologous triple‐disulfide bridged kringle domains, has previously been shown to exhibit profound inhibition of endothelial cell proliferation in vitro and angiogenesis in vivo. It was also demonstrated that angiostatin could suppress the growth of a variety of tumors via the blocking of angiogenesis. The primary aim of our study was to characterize the kringle domains of angiostatin for their inhibitory activities of endothelial cell migration in order to elucidate their contributions to the anti‐angiogenic function of angiostatin. In this report, we demonstrate for the first time that the kringles of angiostatin play different roles in inhibiting endothelial cell migration, a crucial process in angiogenesis. Kringle 4, which has only marginal anti‐proliferative activity, is among the most potent fragments in inhibiting endothelial cell migration (IC50 of approximately 500 nM). In contrast, kringle 1–3, which is equivalent to angiostatin in inhibiting endothelial cell proliferation, manifests only a modest anti‐migratory effect. The combination of kringle 1–3 and kringle 4 results in an anti‐migratory activity comparable to that of angiostatin. When kringle 1 is removed from kringle 1–3, the resulting kringle 2–3 becomes more potent than kringle 1–3. This implies that kringle 1, although virtually ineffective in inhibiting endothelial cell migration, may influence the conformation of kringle 1–3 to alter its anti‐migratory activity. We also show that disruption of the kringle structure by reducing/alkylating agents markedly attenuates the anti‐migratory activity of angiostatin, demonstrating the significance of kringle conformation in maintaining the anti‐angiogenic activity of angiostatin. Our data suggest that different kringle domains may contribute to the overall anti‐angiogenic function of angiostatin by their distinct anti‐migratory activities.—Ji, W. R., Castellino, F. J., Chang, Y., DeFord, M. E., Gray, H., Villarreal, X., Kondri, M. E., Marti, D. N., Llinás, M., Schaller, J., Kramer, R. A., and Trail, P. A. Characterization of kringle domains of angiostatin as antagonists of endothelial cell migration, an important process in angiogenesis. FASEB J. 12, 1731–1738 (1998)

A total fibrinogen deficiency is compatible with the development of pulmonary fibrosis in mice.

In addition to their well-known roles in hemostasis, fibrinogen (Fg) and fibrin (Fn) have been implicated in a number of other physiological and pathophysiological events. One of these involves the fibroproliferative response after acute lung injury, which is the focus of the current study. Mice with a total Fg deficiency (FG(-/-)) were generated by breeding heterozygous (FG(+/-)) pairs, each of which contained an allele with a targeted deletion of its Fg-gamma-chain gene. The resulting FG(-/-) animals did not possess detectable plasma Fg. FG(-/-) mice were then used to assess the roles of Fg and Fn in a bleomycin-induced acute lung injury model. Intratracheal administration of bleomycin in wild-type and FG(-/-) mice resulted in equivalent deposition of interstitial collagen and fibrotic lesions at days 7 and 14 after administration. This indicates that Fg and/or Fn are not essential for the development of bleomycin-induced pulmonary fibrosis.

Development of Pulmonary Fibrosis in Fibrinogen-Deficient Mice

Abstract: Bleomycin is an antineoplastic drug commonly used for the treatment of many carcinomas and lymphomas. Its toxic side effect on lung tissue is a major limitation to its use, with approximately 3–5% of patients affected. Although the number of affected patients is small, the damage incurred by bleomycin in these patients is often irreversible and, at times, fatal. A number of therapies have been shown to be effective in animal studies to minimize damage, but to date no “magic bullet” has been identified. Many proteins of the fibrinolytic system have been implicated as playing a role in the progression of the disease, one of which is fibrinogen (Fg) acting in the context of a fibroproliferative agent. Its presence correlates with an upregulation of plasminogen activator inhibitor‐1 and tissue factor in alveolar cells surrounding the lesion area. It is believed that Fg participates in the activation and migration of fibroblasts and provides a scaffold, in the form of fibrin, for cell migration following induction of acute lung injury. To further understand the mechanism of injury following bleomycin treatment and the possible role of fibrinogen therein, mice have been generated with a targeted deletion of the gamma‐chain of Fg, which resulted in the absence of detectable circulating Fg. The offsprings of Fg heterozygous mice (FG+/−) mice follow Mendelian distributions indicating no embryonic lethality with this deletion. Approximately one‐half of the Fg‐deficient (FG−/−) neonates exhibited bleeding episodes, approximately one‐half of which were fatal. For the pulmonary fibrosis study, FG−/− mice and wildtype littermates were administered a bleomycin solution intratracheally and the disease was allowed to progress for two weeks. The mice were then sacrificed, the left lung was excised for hydroxyproline analysis, the right lung was processed for histologic profiling. Examination of trichrome stained sections, surprisingly, revealed no qualitative difference between wildtype and FG−/− animals. The extent and pattern of the deposition of collagen were also similar. These results were quantitatively confirmed by hydroxyproline analysis, which revealed equivalent increases in collagen content between wildtype and FG−/− animals when compared to appropriate saline controls. Analysis of the early acute inflammatory stage of the disease showed a difference in the neutrophil population between days three and five of the disease. These studies suggest that, although fibrinogen is not required for collagen deposition at the later stage of the disease, it may play a role in the early acute inflammation stage.

Cathepsin E Is a Specific Marker of Dysplasia in APCMin/+ Mouse Intestine

Transcriptional profiling of APCMin/+ mouse intestinal epithelial tissue has revealed that cathepsin E (catE) manifests high relative expression in adenomas and carcinomas relative to normal epithelium. Real-time RT-PCR data presented previously confirm the presence of catE transcript in APCMin/+ adenomatous cells compared with samples derived from normal APCMin/+ and wild-type tissue. At the protein level, strong, highly specific immunohistochemical staining for catE is displayed in dysplastic lesions of APCMin/+ mice. Using Western immunoblot analyses, it was additionally established that the urine of tumor-bearing mice contains higher levels of the monomeric form of catE than their wild-type counterparts. These results authenticate the relationship between transcript abundance and protein levels in transformed tissue and suggest potential utility for catE as a marker for the inception and progression of intestinal cancers.

Project Development Teams: A Novel Mechanism for Accelerating Translational Research

The trend in conducting successful biomedical research is shifting from individual academic labs to coordinated collaborative research teams. Teams of experienced investigators with a wide variety of expertise are now critical for developing and maintaining a successful, productive research program. However, assembling a team whose members have the right expertise requires a great deal of time and many resources. To assist investigators seeking such resources, the Indiana Clinical and Translational Sciences Institute (Indiana CTSI) created the Project Development Teams (PDTs) program to support translational research on and across the Indiana University–Purdue University Indianapolis, Indiana University, Purdue University, and University of Notre Dame campuses. PDTs are multidisciplinary committees of seasoned researchers who assist investigators, at any stage of research, in transforming ideas/hypotheses into well-designed translational research projects. The teams help investigators capitalize on Indiana CTSI resources by providing investigators with, as needed, mentoring and career development; protocol development; pilot funding; institutional review board, regulatory, and/or nursing support; intellectual property support; access to institutional technology; and assistance with biostatistics, bioethics, recruiting participants, data mining, engaging community health, and collaborating with other investigators. Indiana CTSI leaders have analyzed metrics, collected since the inception of the PDT program in 2008 from both investigators and team members, and found evidence strongly suggesting that the highly responsive teams have become an important one-stop venue for facilitating productive interactions between basic and clinical scientists across four campuses, have aided in advancing the careers of junior faculty, and have helped investigators successfully obtain external funds.