Varying capacities for replication of rat adipocyte precursor clones and adipose tissue growth.

Abstract

Rat adipocyte precursor populations contain clones varying in capacity for replication. In this study we explored factors controlling the frequency of clones of varying replicative capacities (clonal composition). We also explored the relationship between this frequency and fat depot growth.In perirenal and epididymal depots clonal composition was identical bilaterally; perirenal depots contained more extensively replicating clones. Although there were large interanimal differences in clonal composition, variation between animals was always in the same direction for both depots. Clonal composition was unaffected by undernutrition while with animal growth the frequency of the most extensively replicating clones was reduced. Differentiation of precursors occurred in all clones, while differentiation did not occur in skin fibroblasts cloned under identical conditions. Clonal composition and mature fat cell number were related in that fat cell numbers were identical bilaterally in both depots and increased more extensively with growth in perirenal than epididymal tissue.We conclude (a) that clonal composition of adipocyte precursor populations is regulated genetically and by age, (b) that this composition determines, at least in part, the capacity for adipose depot growth.

Increased CUG Triplet Repeat-binding Protein-1 Predisposes to Impaired Adipogenesis with Aging

“…They were considered to be stage 5 when they contained 2-5 large droplets and stage 6 when they contained a single large inclusion that laterally displaced the nucleus. The lipid nature of these inclusions was confirmed by staining with oil red O (31,32). In previous experiments, we demonstrated that inclusions of the type in stage 4 to 6 cells only appear in differentiating preadipocytes and not other cell types (e.g.…”

“…In previous experiments, we demonstrated that inclusions of the type in stage 4 to 6 cells only appear in differentiating preadipocytes and not other cell types (e.g. lung fibroblasts) in the differentiation medium we used, and that the proportion of such cells is highly correlated with glycerol-3-phosphate dehydrogenase activity (12,31,32).…”

Fat Depot–Specific Characteristics Are Retained in Strains Derived From Single Human Preadipocytes

“…6B). Such cells are not seen in cells in skin fibroblasts grown under these conditions (9), confirming the adipocytic lineage of the hTERT strains. aP2, PPAR␥2, and C/EBP␣ mRNA abundance was measured in the subcutaneous and omental strains following exposure to differentiation medium for 15 days (Fig.…”

“…Preadipocytes, the progenitors that differentiate into new fat cells, are an important cell type in their own right, accounting for 15-50% of cells in fat (4). Some investigators have reported that preadipocytes cultured under identical conditions originating from different depots from the same individuals vary in capacities for replication, differentiation, and apoptosis, consistent with the view that inherent preadipocyte characteristics contribute to distinct features of different depots (5)(6)(7)(8)(9)(10)(11)(12). Others, however, have not found regional variation in some of these preadipocyte characteristics (13)(14)(15).…”

“…Since fat tissue turns over in adulthood (4), inherent, fat depotdependent differences among the preadipocytes from which new fat cells arise could also contribute. Indeed, preadipocytes appear to vary in capacities for replication, adipogenesis, and apoptosis among fat depots, although there has been debate about this (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)28). Reasons for discrepant findings across studies may include differences in culture conditions, duration of exposure to agents such as those that induce adipogenesis, characteristics of subjects from whom preadipocytes were isolated, or contamination of primary cultures by other cell types potentially present in differing quantities among different fat depots.…”