Extracellular matrix development during differentiation into adipocytes with a unique increase in type V and VI collagen

Abstract

In order to study how adipose conversion affects the extracellular environment, levels of extracellular matrix (ECM) proteins during differentiation were analyzed by 125I-labeled antibody binding to each specific primary antibody. When confluent bovine intramuscular preadipocytes (BIP) were stimulated with adipogenic medium, there was a significant accretion on the cell surface of type I-VI collagens, laminin and fibronectin, compared with undifferentiated cells. The deposition amount of ECM proteins had reached near maximal levels at an early stage of differentiation and lasted throughout the culture. However, the increasing manners were not all the same in these eight proteins. Type V and type VI collagen tended to show a transient decline after the rapid rise at the beginning of stimulation, and fibronectin instead, subsequently decreased. Further analysis by immunocytochemical staining showed that remodeling occurred in type V and VI collagen matrices during this period; extensive fibrillar networks seen at 10 d after stimulation were quite unlike that formed earlier. These specific increases and development of matrix during adipocyte differentiation imply some significance for organizing fat lobules in each ECM proteins, especially type V and VI collagens.

Characterization of PSPA Cell Differentiation,an Established Pig Preadipocyte Cell Line as an In Vitro Model for Pig Fat Development

“…These newly accumulated extracellular matrix (ECM) macromolecules are comprised of various numbers of collagens, structural glycoproteins and proteoglycans. As previously reported in both mouse and bovine adipocytes (Kubo et al 2000, Nakajima et al 2002a, we also observed the same phenomenon with porcine adipocytes in which a prominent fibrillar network of collagens developed only in differentiated cells, thus forming fat cell clusters (unpublished data). In addition, impairing these ECM networks by treatment of ethyl-3,4-dihydroxybenzoate, a specific inhibitor of collagen synthesis, reduced the level of adipogenesis in mice and bovine (Ibrahimi et al 1992, Nakajima et al 2002b, as well as pig adipocytes (unpublished data).…”

Metabolic Dysregulation and Adipose Tissue Fibrosis: Role of Collagen VI

“…Collagen VI is an ideal candidate due to its relatively abundant and highly enriched expression in adipose tissue. It is the most highly expressed collagen in differentiated adipocytes and undergoes dramatic structural changes during adipogenesis (38). Collagen VI fibrils alter their appearance during differentiation of 3T3-L1 preadipocytes, switching from a thin fibril texture at day 4 of differentiation to a very thick appearance in fully differentiated adipocytes.…”

Effects of dihydrotestosterone on adipose tissue measured by serial analysis of gene expression

“…The downregulation of these and other keratins in this study may affect adipocyte cell shape. Extracellular matrix (ECM) components, such as collagen types I, III, IV, V and VI, increase three-to sixfold under adipogenic conditions (Nakajima et al 2002). Moreover, MMP-2 is also involved in adipocyte development, since it regulates the balance between ECM deposition and degradation.…”