Knockdown of PTRF ameliorates adipocyte differentiation and functionality of human mesenchymal stem cells

Abstract

Healthy expansion of human adipose tissue requires mesenchymal stem cells (hMSC) able to proliferate and differentiate into mature adipocytes. Hence, characterization of those factors that coordinate hMSC-to-adipocyte transition is of paramount importance to modulate the adipose tissue expansion. It has been previously reported that the adipogenic program of hMSC can be disrupted by upregulating caveolar proteins, and polymerase I and transcript release factor (PTRF) is an integral component of caveolae, highly expressed in adipose tissue. Here, we hypothesized that the role of PTRF in adipocyte functionality might stem from an effect on hMSC. To test this hypothesis, we isolated hMSC from the subcutaneous fat depot. We found an upregulated expression of the PTRF associated with decreased adipogenic potential of hMSC, likely due to the existence of senescent adipocyte precursors. Employing short hairpin RNA-based constructs to stably reduce PTRF, we were able to restore insulin sensitivity and reduced basal lipolysis and leptin levels in human adipocytes with high levels of PTRF. Additionally, we pinpointed the detrimental effect caused by PTRF on the adipose tissue to the existence of senescent adipocyte precursors unable to proliferate and differentiate into adipocytes. This study provides evidence that impaired adipocyte functionality can be corrected, at least partially, by PTRF downregulation and warrants further in vivo research in patients with dysfunctional adipose tissue to prevent metabolic complications.

Pharmacologic concentrations of linezolid modify oxidative phosphorylation function and adipocyte secretome

“…Each lot of hASCs originates from a single donor of human lipoaspirate tissue, and the two previously characterized lots used here [7], are named hASCs-1 and hASCs-2. In some experiments, we used hASCs derived from 13 different donors, after a signed informed consent was obtained [19].…”

Maresin 1 improves insulin sensitivity and attenuates adipose tissue inflammation in ob/ob and diet‐induced obese mice

“…All donors signed the written consent, and the study was approved by the local Institutional Review Board (CEIC-A) and the Ethics Committee of the University of Navarra. hMSCs were isolated as described in Perez-Diaz et al (28) and maintained in 10% fetal bovine serum (FBS) low-glucose DMEM at 37°C and 5% CO 2 . After reaching confluence, hMSCs were differentiated into adipocytes using an adipogenic cocktail that included 500 mM IBMX, 1.67 mM insulin, 1 mM dexamethasone, 1 mM rosiglitazone, and 10% FBS highglucose medium for 6 d. After 3 d, the medium was removed, and new adipogenic cocktail was added.…”

PTRF acts as an adipokine contributing to adipocyte dysfunctionality and ectopic lipid deposition

“…Obesity occurs with an expansion of the adipose tissue to store energy surplus. Increases of adipocyte number (hyperplasia) and adipocyte size (hypertrophy) jointly determine adipose expansion and endogenous PTRF plays an important role in regulating the balance between those two mechanisms [15,16]. In this work, we showed that PTRF can also be found in human plasma and increases adipocyte hypertrophy and senescence in vitro.…”

“…Polymerase I and transcription release factor (PTRF) production by the adipocytes has been proposed as a mechanism leading to a dysfunctional AT [16]. In a previous work, we found an upregulated expression of the PTRF associated with senescence and decreased adipogenic potential of human adipocyte precursors [15].…”

“…Furthermore, we demonstrated for the first time differences in PTRF production between subcutaneous and visceral fat tissue in obese individuals and also we found a positive correlation between circulating PTRF and the concentration of PTRF in the visceral fat depot. We, and others, have defined some mechanisms whereby PTRF plays a crucial role in impeding a healthy adipose tissue expansion [1,15,16]. For this work, we set out to test whether PTRT might have some endocrine/paracrine influence beyond its effect as endogenous factor.…”