A novel role for neural cell adhesion molecule in modulating insulin signaling and adipocyte differentiation of mouse mesenchymal stem cells

Abstract

SummaryNeural cell adhesion molecule (NCAM) has recently been found on adult stem cells, but its biological significance remains largely unknown. In this study, we used bone-marrow-derived mesenchymal stem cells (MSCs) from wild-type and NCAM knockout mice to investigate the role of NCAM in adipocyte differentiation. It was demonstrated that NCAM isoforms 180 and 140 but not NCAM-120 are expressed on almost all wild-type MSCs. Upon adipogenic induction, Ncam -/-MSCs exhibited a marked decrease in adipocyte differentiation compared with wild-type cells. The role of NCAM in adipocyte differentiation was also confirmed in NCAM-silenced preadipocyte 3T3-L1 cells, which also had a phenotype with reduced adipogenic potential. In addition, we found that Ncam -/-MSCs appeared to be insulin resistant, as shown by their impaired insulin signaling cascade, such as the activation of the insulin-IGF-1 receptor, PI3K-Akt and CREB pathways. The PI3K-Akt inhibitor, LY294002, completely blocked adipocyte differentiation of MSCs, unveiling that the reduced adipogenic potential of Ncam -/-MSCs is due to insulin resistance as a result of loss of NCAM function. Furthermore, insulin resistance of Ncam -/-MSCs was shown to be associated with induction of tumor necrosis factor  (TNF-), a key mediator of insulin resistance. Finally, we demonstrated that re-expression of NCAM-180, but not NCAM-140, inhibits induction of TNF- and thereby improves insulin resistance and adipogenic potential of Ncam -/-MSCs. Our results suggest a novel role of NCAM in promoting insulin signaling and adipocyte differentiation of adult stem cells. These findings raise the possibility of using NCAM intervention to improve insulin resistance.

Neural cell adhesion molecule regulates chondrocyte hypertrophy in chondrogenic differentiation and experimental osteoarthritis

“…The Ncam −/− (knockout; KO) mice were generated on a C57/BL6 background as previously described . Wild‐type (WT) and KO MSCs were obtained from 8‐week‐old male mice as previously described . Briefly, cells were harvested from mouse bone marrow and cultured in low glucose Dulbecco's modified Eagle's medium (DMEM‐LG) containing 10% FBS, 100 IU/mL penicillin and 100 g/mL streptomycin.…”

“…NCAM is also expressed in MSCs, but its function remains largely unknown. We have previously demonstrated that NCAM promotes adipocyte differentiation of murine MSCs via PI3K‐Akt pathways . NCAM is also involved in chondrogenesis.…”

“…We have previously demonstrated that NCAM promotes adipocyte differentiation of murine MSCs via PI3K-Akt pathways. 18 NCAM is also involved in chondrogenesis. In the process of chondrogenic differentiation, NCAM is expressed in prechondrogenic cells and increased during cell condensation, 19 but it becomes undetectable in hypertrophic chondrocytes.…”

MicroRNAs as novel regulators of stem cell fate

“…The fate of HSCs is regulated by small molecules that promote self-renewal [181][182][183] . Using small molecules, multipotent MSCs can differentiate into various non-hematopoietic cells, such as chondrocytes [134,184] , osteoblasts [185,186] , hepatocytes [187] , cardiomyocytes [188,189] , adipocytes [190,191] and neuronal-like cells [192][193][194] . Additionally, the maintenance of MSCs is associated with the Wnt signaling pathway [195,196] .…”

An Open Source Based High Content Screening Method for Cell Biology Laboratories Investigating Cell Spreading and Adhesion

“…Even though cell-substrate adhesion modulating proteins are classically described to be important for cell migration it becomes increasingly apparent that these molecules can have a wide range of additional functions [1-3]. Vice versa, numerous proteins identified earlier as being involved in adhesion- or migration-unrelated cellular events are increasingly being recognized to also modulate cell attachment, spreading or migratory behavior of cells [4-6].…”