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S-nitrosoglutathione reductase-dependent PPAR? denitrosylation participates in MSC-derived adipogenesis and osteogenesis.

ABSTRACT: Bone marrow-derived mesenchymal stem cells (MSCs) are a common precursor of both adipocytes and osteoblasts. While it is appreciated that PPAR? regulates the balance between adipogenesis and osteogenesis, the roles of additional regulators of this process remain controversial. Here, we show that MSCs isolated from mice lacking S-nitrosoglutathione reductase, a denitrosylase that regulates protein S-nitrosylation, exhibited decreased adipogenesis and increased osteoblastogenesis compared with WT MSCs. Consistent with this cellular phenotype, S-nitrosoglutathione reductase-deficient mice were smaller, with reduced fat mass and increased bone formation that was accompanied by elevated bone resorption. WT and S-nitrosoglutathione reductase-deficient MSCs exhibited equivalent PPAR? expression; however, S-nitrosylation of PPAR? was elevated in S-nitrosoglutathione reductase-deficient MSCs, diminishing binding to its downstream target fatty acid-binding protein 4 (FABP4). We further identified Cys 139 of PPAR? as an S-nitrosylation site and demonstrated that S-nitrosylation of PPAR? inhibits its transcriptional activity, suggesting a feedback regulation of PPAR? transcriptional activity by NO-mediated S-nitrosylation. Together, these results reveal that S-nitrosoglutathione reductase-dependent modification of PPAR? alters the balance between adipocyte and osteoblast differentiation and provides checkpoint regulation of the lineage bifurcation of these 2 lineages. Moreover, these findings provide pathophysiological and therapeutic insights regarding MSC participation in adipogenesis and osteogenesis.

SUBMITTER: Cao Y

PROVIDER: S-EPMC4396480 | biostudies-other | 2015 Apr

REPOSITORIES: biostudies-other

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S-nitrosoglutathione reductase-dependent PPARγ denitrosylation participates in MSC-derived adipogenesis and osteogenesis.

Cao Yenong Y Gomes Samirah A SA Rangel Erika B EB Paulino Ellena C EC Fonseca Tatiana L TL Li Jinliang J Teixeira Marilia B MB Gouveia Cecilia H CH Bianco Antonio C AC Kapiloff Michael S MS Balkan Wayne W Hare Joshua M JM

The Journal of clinical investigation 20150323 4

Bone marrow-derived mesenchymal stem cells (MSCs) are a common precursor of both adipocytes and osteoblasts. While it is appreciated that PPARγ regulates the balance between adipogenesis and osteogenesis, the roles of additional regulators of this process remain controversial. Here, we show that MSCs isolated from mice lacking S-nitrosoglutathione reductase, a denitrosylase that regulates protein S-nitrosylation, exhibited decreased adipogenesis and increased osteoblastogenesis compared with WT ...[more]

PMID: 25798618

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Project description:IntroductionSkeletal aging is associated not only with alterations in osteoblast (OB) and osteoclast (OC) number and activity within the basic metabolic unit, but also with increased marrow adiposity. Peroxisome proliferator-activated receptor gamma (PPAR?) is commonly considered the master transcriptional regulator of adipogenesis, however, it has known roles in osteoblast and osteoclast function as well. Here, we designed a lentiviral delivery system for PPAR? shRNA, and examined its effects in vitro on bone marrow stromal cells (BMSC) and in a mouse intramedullary injection model.MethodsPPAR? shRNA was delivered by a replication-deficient lentiviral vector, after in vitro testing to confirm purity, concentration, and efficacy for Pparg transcript reduction. Next, control green fluorescent protein lentivirus or PPAR? shRNA expressing lentivirus were delivered by intramedullary injection into the femoral bone marrow of male SCID mice. Analyses included daily monitoring of animal health, and postmortem analysis at 4 weeks. Postmortem analyses included high resolution microcomputed tomography (microCT) reconstructions and analysis, routine histology and histomorphometric analysis, quantitative real time polymerase chain reaction analysis of Pparg transcript levels, and immunohistochemical analysis for markers of adipocytes (PPAR?, fatty acid binding protein 4 [FABP4]), osteoblasts (alkaline phosphatase [ALP], osteocalcin [OCN]), and osteoclasts (tartrate-resistant acid phosphatase [TRAP], Cathepsin K).ResultsIn vitro, PPAR? shRNA delivery significantly reduced Pparg expression in mouse BMSC, accompanied by a significant reduction in lipid droplet accumulation. In vivo, a near total reduction in mature marrow adipocytes was observed at 4 weeks postinjection. This was accompanied by significant reductions in adipocyte-specific markers. Parameters of trabecular bone were significantly increased by both microCT and histomorphometric analysis. By immunohistochemical staining and semi-quantification, a significant increase in OCN+osteoblasts and decrease in TRAP+multinucleated osteoclasts was observed with PPAR? shRNA treatment.DiscussionThese findings suggest that acute loss of PPAR? in the bone marrow compartment has a significant role beyond anti-adipose effects. Specifically, we found pro-osteoblastogenic, anti-osteoclastic effects after PPAR? shRNA treatment, resulting in improved trabecular bone architecture. Future studies will examine the isolated and direct effects of PPAR? shRNA on OB and OC cell types, and it may help determine whether PPAR? antagonists are potential therapeutic agents for osteoporotic bone loss.

Project description:Mesenchymal stem cells (MSCs), also known as multipotent stromal cells, are used in clinical trials. However, the use of MSCs for medical treatment of patients poses a potential problem due to the possibility of transdifferentiation into unwanted tissues. Disruption of the balance during MSC differentiation leads to obesity, skeletal fragility, and osteoporosis. Differentiation of MSCs into either adipocytes or osteoblasts is transcriptionally regulated by the two key transcription factors PPAR?2 and Runx2. PPAR?2 is highly expressed during adipocyte differentiation and regulates expression of genes involved in adipogenesis. Runx2 induces osteogenic gene expression and, thereby, increases osteoblast differentiation. Although transcriptional modulation of PPAR?2 has been investigated in adipogenesis, the underlying molecular mechanisms to control the balance between adipogenesis and osteogenesis in MSCs remain unclear. In this study, the role of sLZIP in regulation of PPAR?2 transcriptional activation was investigated along with sLZIP's involvement in differentiation of MSCs into adipocytes and osteoblasts. sLZIP interacts with PPAR?2 and functions as a corepressor of PPAR?2. sLZIP enhances formation of the PPAR?2 corepressor complex through specific interaction with HDAC3, resulting in suppression of PPAR?2 transcriptional activity. We found that sLZIP prevents expression of PPAR?2 target genes and adipocyte differentiation both in vitro and in vivo. sLZIP also upregulates Runx2 transcriptional activity via inhibition of PPAR?2 activity, and promotes osteoblast differentiation. sLZIP transgenic mice exhibited enhanced bone mass and density, compared with wild-type mice. These results indicate that sLZIP has a critical role in the regulation of osteogenesis and bone development. However, sLZIP does not affect chondrogenesis and osteoclastogenesis. We propose that sLZIP is a novel PPAR?2 modulator for control of the balance between adipogenesis and osteogenesis during MSC differentiation, and that sLZIP can be used as a therapeutic target molecule for treatment of obesity, osteodystrophy, and osteoporosis.

Dataset Information

S-nitrosoglutathione reductase-dependent PPAR? denitrosylation participates in MSC-derived adipogenesis and osteogenesis.

Publications

S-nitrosoglutathione reductase-dependent PPARγ denitrosylation participates in MSC-derived adipogenesis and osteogenesis.

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