Increase of gremlin 2 with age in human adipose-derived stromal/stem cells and its inhibitory effect on adipogenesis

Abstract

IntroductionAdipose-derived stromal/stem cells (ASCs) have attracted attention as a promising material for regenerative medicine. Previously, we reported an age-related decrease in the adipogenic potential of ASCs from human subjects and found that the individual difference in this potential increased with age, although the mechanisms remain unclear. Recently, other groups demonstrated that a secreted antagonist of bone morphogenetic protein (BMP) signaling, Gremlin 2 (GREM2), inhibits the differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) into osteoblasts and the adipogenesis of 3T3-L1 cell. Here, we examined the effects of GREM2 on the differentiation of ASCs into adipocytes.MethodsTo examine changes in GREM2 expression levels with age, immunohistochemistry was performed on subcutaneous adipose tissues from subjects 12–97 years of age. Next, GREM2 gene expression levels in ASCs collected from subjects 5–90 years of age were examined by RT-PCR, and the change with age and correlation between the expression level and the adipogenic potential of ASCs were analyzed. In addition, to assess whether GREM2 affects adipogenesis, ASCs (purchased from a vendor) were cultured to induce adipogenesis with recombinant GREM2 protein, and siRNA-induced GREM2 knockdown experiment was also performed using aged ASCs.ResultsIn adipose tissues, GREM2 expression was observed in cells, including ASCs, but not in mature adipocytes, and the expression level per cell increased with age. GREM2 expression levels in ASCs cultured in vitro also increased with age, and the individual differences in the level increased with age. Of note, partial correlation analysis controlled for age revealed that the adipogenic potential of ASCs and the GREM2 gene expression level were negatively correlated. Furthermore, based on a GREM2 addition experiment, GREM2 has inhibitory effects on the adipogenesis of ASCs through activation of Wnt/β-catenin signaling. On the other hand, GREM2 knockdown in aged ASCs promoted adipogenesis.ConclusionsThe GREM2 expression level was confirmed to play a role in the age-related decrease in adipogenic potential observed in ASCs isolated from adipose tissues as well as in the enhancement of the individual difference, which increased with age. GREM2 in adipose tissues increased with age, which suggested that GREM2 functions as an inhibitory factor of adipogenesis in ASCs.

GREM2 is associated with human central obesity and inhibits visceral preadipocyte browning

“…However, other experimental data, especially for Grem2 concentrations in the portal vein and different fat depots, still require extensive evidence in human subjects under various pathophysiological stimuli. 15 In addition, the expression profile of GREM2 in various human tissues needs more detailed characterization.…”

“… 11 , 12 , 13 As two attractive BMPs, BMP4 mediates the browning of white adipose tissues (WATs) to improve glucose and energy homeostasis, 12 while BMP7 acts as a key regulator of classical brown adipose tissue (BAT) development. 14 In comparison with BMP members, few studies have investigated the clinical implications and biological roles of BMP antagonists in metabolic disorders, among which Gremlin 2 (GREM2) was reported to increase in adipose tissues with aging 15 and regulate the adipogenesis 16 and osteogenesis. 17 However, the effects of GREM2 on the browning program and central obesity are poorly understood.…”

Gremlin 2 suppresses differentiation of stem/progenitor cells in the human skin

“…We also showed that GREM2 expression was higher in the skin from the elderly than from the young and that the individual differences GREM2 expression varied more largely in the elderly [ 18 ]. Moreover, we showed that GREM2 suppressed the differentiation of human adipose-derived stromal/stem cells (ASCs) [ 29 ]. These findings suggest that GREM2 expression increases with age and that GREM2 plays a role as a SASP factor in affecting the homeostasis of the skin and may directly affect stem cells in the skin.…”

“…These findings indicate that GREM2 has a great influence on the proliferation and differentiation of stem cells. In our previous study, we focused on GREM2 as a SASP factor in the skin and found that GREM2 suppressed the differentiation of stem cells in the subcutaneous adipose tissue [ 29 ]. However, whether GREM2 is expressed in the epidermis and dermis as well as its effect on epidermal and dermal stem cells were unclear.…”

Generation of cardiomyocytes from human induced pluripotent stem cells resembling atrial cells with ability to respond to adrenoceptor agonists

“…Their study thus provides molecular insights that aid in developing strategies for the generation of atrial cardiomyocytes from pluripotent stem cells. Additionally, other groups have inspected Gremlin2 as a pro-atrial differentiation factor and reported promising results [17]. Gremlin 2 is a signalling molecule involved in cardiac development and atrial specific differentiation as cardiac progenitor cells migrate [17; 18; 19].…”