Hormonal responsiveness of a preadipose cell line derived from newborn mouse calvaria

Abstract

We established a clonal preadispose cell line from newborn mouse calvaria. Cells of this cell line, designated MC3T3-G2/PA6, had the capacity to convert to adipose cells, to accumulate triglycerides in their cytoplasm, and to mature to differentiated fat cells in a resting state. This adipose conversion was markedly accelerated by addition of dexamethasone, which was the most potent inducer among the steroid hormones tested. The presence of dexamethasone was needed during the steroid hormones tested. The presence of dexamethasone was needed during logarithmic growth phase for maximal conversion. The frequency of adipose conversion was dependent on exposure time to the hormone, but cells already committed to differentiation continued to accumulate lipid and developed into mature adipose cell even in its absence. This indicates that the hormone accelerates the initiation of the adipose conversion, but is not required for the ongoing conversion process. In fact, it was rather inhibitory for the process of fat accumulation. Insulin alone slightly inhibited the adipose conversion, but its combination with dexamethasone neutralized the above inhibitory effect of dexamethasone. The responsiveness of this cell line is consistent with that observed for mouse bone marrow preadipocytes in primary culture but differs from that for preadipose cell lines derived from extramedullary tissues. These results strongly suggest that the MC3T3-G2/PA6 cell line was derived from bone marrow.

The Bone-specific Expression of Runx2 Oscillates during the Cell Cycle to Support a G1-related Antiproliferative Function in Osteoblasts

“…Cell Culture and Synchronization-Experiments were performed with osteoblastic cells, which include rat calvarial osteoblasts, temperature-sensitive SV40 T antigen-transformed human osteoblasts (48), mouse MC3T3 cells (49), osteosarcoma cells (rat ROS17/2.8 and human SAOS-2 cells), chondrocytic cells (mouse ATDC5 clonal teratocarcinoma cells) (50), as well as primary human articular chondrocytes and mesenchymal progenitor cells (mouse C2C12 cells) (51). The osteoblastic cell line MC3T3-E1 was used for the majority of our experiments.…”

Insulin Signaling in Adipocytes Differentiated from Mouse Stromal MC3T3-G2/PA6 Cells

“…5) Preadipocytes required insulin, glucocorticoids and phosphodiesterase inhibitors, as external inducers, for the trigger of full differentiation into mature adipocytes. [20][21][22] Of those, insulin is well known to play a key role in adipocyte differentiation in vivo and in vitro.…”

“…5) Greenberger reported that corticosteroids accumulated lipids in primary cultured mammalian bone marrow preadipocytes, but insulin did not. 6,7) In addition, the adipogenesis in PA6 cells is also markedly accelerated by the addition of dexamethasone, but insulin is not required for the process.…”

“…6,7) In addition, the adipogenesis in PA6 cells is also markedly accelerated by the addition of dexamethasone, but insulin is not required for the process. 5) Insulin is a major hormone controlling critical energy functions such as glucose and lipid metabolism. Its effects result from insulin binding to a membrane receptor (insulin receptor), which is expressed highly on insulin target tissues, such as the liver, muscles and adipocytes.…”

“…5) was purchased from the Riken Bioresource Center, Tsukuba, Japan, and maintained in a-MEM supplemented with 10% heat-inactivated FBS and 60 mg/ml kanamycin in an atmosphere of 5% CO 2 at 37°C. Differentiation was induced by treating the confluent cells with a-MEM containing 0.5 mM IBMX, 0.25 mM Dex and 10% FBS for 4 d. The cells were further cultured in a-MEM supplemented with 10% FBS every other day for the subsequent 4-6 d.…”