HGF Signaling in Adipose Tissue Growth and Metabolism

脂肪组织生长和代谢中的 HGF 信号传导

• 批准号: 7784838
• 负责人: Robert V Considine
• 金额: $ 34.65万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-20 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7784838
• 关键词: Acute; Address; Adipocytes; Adipose tissue; Animals; Apoptosis; Area; Attenuated; BALB/c Nude Mouse; Biology; Blood Vessels; Blood capillaries; Cardiovascular Diseases; Cells; Complex; Complex Mixtures; Critiques; Data; Development; Diabetes Mellitus; Endothelial Cells; Event; Fatty acid glycerol esters; Foundations; Funding; Future; Genetic; Genomics; Growth; Growth Factor Overexpression; Hepatocyte Growth Factor; Hormones; Human; Immune response; Immunocompetent; Immunodeficient Mouse; Immunologic Deficiency Syndromes; Impairment; Implant; Inbred BALB C Mice; Individual; Investigation; Left; Malignant Neoplasms; Metabolism; Mind; Modeling; Molecular; Mus; Nude Mice; Obesity; Pericytes; Physiological; Process; Property; Public Health; Published Comment; Publishing; Regulation; Reporting; Research; Rivers; Role; Signal Transduction; Skin; Solid; Stem cells; Structure; Surface; System; Testing; Therapeutic Intervention; Tissue Expansion; Tissues; Tube; Vascular blood supply; Vascularization; Xenograft procedure; angiogenesis; autocrine; base; capillary; experience; in vivo; innovation; insight; interest; model development; monolayer; mouse model; neovascularization; novel; novel strategies; overexpression; prevent; public health relevance; research study; response

We appreciate the significant enthusiasm expressed by the reviewers for the previous submission. It was noted in the Summary that the application addresses a very important, interesting and understudied question. Noted strengths of the application were the novel, timely and significant research topic, the high degree of innovation, the solid preliminary data, the experience of the applicant, and the number of improvements made in response to prior reviewer comments. We also thank the reviewers for their continued thoughtful critique and insight into other potential problems and pitfalls. We have addressed these concerns in the current submission which has been tightly focused into a 2 year proposal. Three main points were raised in the critique of the previous application. The Reviewers were very enthusiastic about the in vivo studies proposed in Aim 1, but were concerned about genetic differences in vascularization between C57 and BALB/c nude mice. The reviewers correctly point out that BALB/c mice have less collateral blood vessels and do not remodel as efficiently as do C57 mice (for example see: Chalothorn et al, Physiol Genomics 30:179-91; 2007), and suggest that “effects of HGF knockdown and overexpression need to be interpreted carefully and on the same genetic background”. We fully agree that genetic differences in vascular development must be considered during interpretation of our experiments. In Aim #1 we will investigate the effect of both HGF knockdown and HGF overexpression on fat pad development in BALB/c nude mice, which are routinely used in xenotransplantation experiments due to their immunodeficiency. Although collateral development has not been studied in BALB/c nude mice, we expect that it will be limited as observed in standard BALB/c mice from which the nude mice were derived. We and others have shown that vascularized fat pads develop in BALB/c nude mice and thus do not expect that attenuated collateral development in these mice will prevent completion of our proposed studies. In these experiments, the effect of mouse genetic background will be identical for both the HGF knockdown and HGF overexpression experiments, which will simply interpretation of findings. As suggested by the reviewers, in Aim #1 we will also inject HGF knockdown and overexpressing 3T3-F442A preadipocytes under the skin of C57 mice and evaluate fat pad formation. We have previously carried out an acute fat pad development experiment in HGF overexpressing mice on the C57 background (Bell et al. Am J Physiol 294:E336-44;2008). However, it is not known if implanted cells left longer than 72 h in the host will induce an immune response in immunocompetent C57 mice that will destroy the developing fat pad. If long term fat pad development is not viable in C57 mice, we can also pursue experiments in Nu/Nu mice (CrlLNU-Foxn1nu; Charles River), an outbred immunodeficient mouse that is not associated with any stock or strain. Collateral development in Nu/Nu mice may be more efficient as has been observed for C57 mice. The second general criticism was that Aims 2 and 3 were significant but underdeveloped. To address this concern we will focus in Aim #2 on the experiments that test the ability of preadipocytes with and without competent HGF signaling to function as pericytes to stabilize vascular structures. The proposed experiments will be carried out using the preadipocyte monolayer system as the only model, in order to simplify interpretation of the findings. These experiments, although simplified to a two cell system, were considered highly innovative. Experiments will systematically test if HGF is required for preadipocytes to function as pericytes, and if mature adipocytes are unable to act as pericytes to stabilize vascular structures. These experiments will fill a significant gap in our understanding of preadipocyte pericytic function and provide an important base for further development of this area of investigation. The third criticism was that the “complexity of the system was not rigorously considered.” We address this valid point by elimination of Aim 3, which was underdeveloped, and focusing Aim 2 to directly test the function of HGF in preadipocyte pericytic function. We recognize that vascular development is a complex process in which many factors are likely involved. We also understand that the two component system to be used in Aim #2, which has the advantage of being well-defined, may not fully reflect the complex mixture of cells present in growing adipose tissue. We will keep this latter point in mind as we interpret the findings of experiments in Aim 2, which will provide important information in this understudied area of adipose tissue biology. Overall the changes that have been made focus and strengthen this proposal to elucidate the mechanisms through which HGF regulates vascular development and preadipocyte pericytic function to promote adipose tissue growth. The proposed studies can be completed within a two year funding period, and will provide an important foundation, in a novel area of research, on which future proposals will be based.

我们感谢审稿人对之前提交的材料所表达的极大热情。摘要中指出，该应用程序解决了一个非常重要、有趣和尚未得到充分研究的问题。该申请的优点是研究课题新颖、及时和重要，创新程度高，初步数据扎实，申请人经验丰富，并根据先前审稿人的意见进行了大量改进。我们也感谢审稿人持续的深思熟虑的批评和对其他潜在问题和陷阱的洞察。我们已经在当前的提交中解决了这些问题，该提交已紧密集中在一个为期2年的提案中。