Submitted to: Journal of Animal Science
Publication Type: Review Article
Publication Acceptance Date: 9/25/2011
Publication Date: 9/30/2011
Citation: Hausman, G.J. 2011. The influence of extracelluar matrix on intramuscular and extramuscular adipogenesis. Journal of Animal Science. 90(3):942-9. Interpretive Summary: The material that surrounds or coats many types of cells can have a major influence on cell growth, development and determining what type of cell it will become. The complete coating material from one cell source and a specific major component of the complete coating material called laminin increased many aspects of fat cell development. Furthermore, cell cultures showed that fat cell precursors express the coating components after commitment of precursor cells to fat cells. The growth of intramuscular fat cells may be dependent on cell coating collagen newly made and organized by the fat cell per se. Fat accretion of bovine intramuscular fat cell is inhibited by a general inhibitor of collagen biosynthesis.In conclusion, the existing literature indicates that the role of the cell coating material in fat cell formation may be multi-faceted and/or location dependent.
Technical Abstract: The extracellular matrix (ECM) and specific ECM components can have a major influence on cell growth, development and phenotype. The influence of the ECM and ECM components on adipogenesis in vivo and in vitro will be reviewed. Engelbreth-Holm-Swarm (EHS) substratum and laminin per se markedly increased attachment, spreading, and hypertrophy of preadipocytes in serum free primary cultures of porcine adipose tissue stromal-vascular (S-V) cells. Furthermore, primary cultures of S-V cells showed that preadipocytes express ECM components after preadipocyte recruitment. Staining for plant lectins, type IV collagen and laminin in fetal pig adipose tissue demonstrates that adipocyte reactivity for laminin was strong throughout fetal development and was similar for developing adipocytes and vasculature. However, lectin binding and type IV collagen reactivity of blood vessels preceded that for adipocytes. Therfore, these studies indicated that the ECM and in particular laminin may play a critical role in morphological aspects of preadipocyte development. Specific inhibitors and modulators of collagen synthesis have been used to evaluate the role of collagens in the differentiation of bovine intramuscular preadipocytes (BIP) and other preadipocyte cell lines. Triglyceride accretion of BIP cells was inhibited by a general inhibitor of collagen biosynthesis whereas specific inhibitors and/or modulators of type IV collagen inhibited 3T3-L1 cell differentiation. Further study discovered that compared to collagens types I-IV, type V and VI collagens have an important and active role in BIP adipogenesis. The growth of intramuscular bovine adipose tissue may be dependent on collagen newly synthesized and organized by the adipocyte per se. The role of extracellular or ECM proteolysis in regulating adipogenesis was also reviewed. Many members of the matrix metalloproteinases (MMPs) family are expressed by adipocytes and specific inhibition of MMP-9 greatly reduces adipogenesis in vitro. Possibly, MMPs and other proteases regulate turnover of key adipocyte ECM proteins which are involved in the regulation preadipocyte proliferation and differentiation.