Overexpressed human heme Oxygenase-1 decreases adipogenesis in pigs and porcine adipose-derived stem cells

Brown Algae Dictyopteris divaricata Attenuates Adipogenesis by Modulating Adipocyte Differentiation and Promoting Lipolysis through Heme Oxygenase-1 Activation in 3T3-L1 Cells

The present study aims to explore the probable anti-adipogenesis effect of Dictyopteris divaricata (D. divaricata) in 3T3-L1 preadipocytes by regulating heme oxygenase-1 (HO-1). The extract of D. divaricata retarded lipid accretion and decreased triglyceride (TG) content in 3T3-L1 adipocytes but increased free glycerol levels. Treatment with the extract inhibited lipogenesis by inhibiting protein expressions of fatty acid synthase (FAS) and lipoprotein lipase (LPL), whereas lipolysis increased by activating phosphorylation of hormone-sensitive lipase (p-HSL) and AMP-activated protein kinase (p-AMPK). The extract inhibited adipocyte differentiation of 3T3-L1 preadipocytes through down-regulating adipogenic transcription factors, including peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1). This is attributed to the triggering of Wnt/β-catenin signaling. In addition, this study found that treatment with the extract activated HO-1 expression. Pharmacological approaches revealed that treatment with Zinc Protoporphyrin (ZnPP), an HO-1 inhibitor, resulted in an increase in lipid accumulation and a decrease in free glycerol levels. Finally, three adipogenic transcription factors, such as PPARγ, C/EBPα, and SREBP1, restored their expression in the presence of ZnPP. Analysis of chemical constituents revealed that the extract of D. divaricata is rich in 1,4-benzenediol, 7-tetradecenal, fucosterol, and n-hexadecanoic acid, which are known to have multiple pharmacological properties.

Platelet lysate for expansion or osteogenic differentiation of bone marrow mesenchymal stem cells for 3D tissue constructs

Background

The use of mesenchymal stem cells (MSCs) for the development of tissue-engineered constructs has advanced in recent years. However, future clinically approved products require following good manufacturing practice (GMP) guidelines. This includes using alternatives to xenogeneic-derived cell culture supplements to avoid rejection of the transplants. Consequently, human platelet lysate (PLT) has been adopted as an affordable and effective alternative to foetal bovine serum (FBS) in traditional 2D cultures. However, little is known about its effect in more advanced 3D culture systems.

Methods

We evaluated bone marrow MSCs (BMSCs) proliferation and CD marker expression in cells expanded in FBS or PLT-supplemented media. Differentiation capacity of the BMSCs expanded in the presence of the different supplements was evaluated in 3D type I collagen hydrogels. Furthermore, the effects of the supplements on the process of differentiation were analyzed by using qPCR and histological staining.

Results

Cell proliferation was greater in PLT-supplemented media versus FBS. BMSCs expanded in PLT showed similar osteogenic differentiation capacity in 3D compared with FBS expanded cells. In contrast, when cells were 3D differentiated in PLT they showed lower osteogenesis versus the traditional FBS protocol. This was also the case for adipogenic differentiation, in which FBS supplementation was superior to PLT.

Conclusions

PLT is a superior alternative to FBS for the expansion of MSCs without compromising their subsequent differentiation capacity in 3D. However, differentiation in PLT is impaired. Thus, PLT can be used to reduce the time required to expand the necessary cell numbers for development of 3D tissue engineered MSC constructs.

RNA N6-methyladenosine profiling reveals differentially methylated genes associated with intramuscular fat metabolism during breast muscle development in chicken

Intramuscular fat (IMF) is an important indicator for determining meat quality, and IMF deposition during muscle development is regulated by a complex molecular network involving multiple genes. The N⁶-methyladenosine (m⁶A) modification of mRNA plays an important regulatory role in muscle adipogenesis. However, the distribution of m⁶A and its role in IMF metabolism in poultry has not been reported. In the present study, a transcriptome-wide m⁶A profile was constructed using methylated RNA immunoprecipitation sequence (MeRIP-seq) and RNA sequence (RNA-seq) to explore the potential mechanism of regulating IMF deposition in the breast muscle based on the comparative analysis of IMF differences in the breast muscles of 42 (group G), 126 (group S), and 180-days old (group M) Jingyuan chickens. The findings revealed that the IMF content in the breast muscle increased significantly with the increase in the growth days of the Jingyuan chickens (P < 0.05). The m⁶A peak in the breast muscles of the 3 groups was highly enriched in the coding sequence (CDS) and 3' untranslated regions (3' UTR), which corresponded to the consensus motif RRACH. Moreover, we identified 129, 103, and 162 differentially methylated genes (DMGs) in the breast muscle samples of the G, S, and M groups, respectively. Functional enrichment analyses revealed that DMGs are involved in many physiological activities of muscle fat anabolism. The m⁶A-induced ferroptosis pathway was identified in breast muscle tissue as a new target for regulating IMF metabolism. In addition, association analysis demonstrated that LMOD2 and its multiple m⁶A negatively regulated DMGs are potential regulators of IMF differential deposition in muscle. The findings of the present study provide a solid foundation for further investigation into the potential role of m⁶A modification in regulating chicken fat metabolism.

Shortening of HO1 3'UTRs by Alternative Polyadenylation Suppresses Adipogenesis in 3T3-L1

Appropriately increasing intramuscular fat content can help improve meat quality, so it is necessary to explore the internal molecular mechanism of preadipocyte differentiation. The role of heme oxygenase 1 (HO1) in cell oxidative stress, energy metabolism, cell proliferation, and differentiation has gradually been revealed. Here, we used 3'RACE to identify the full-length 3' untranslated region (3'UTR) of HO1 and found that a very short 3'UTR variant was produced by alternative polyadenylation (APA). HO1 with a long 3'UTR variant was identified as a direct target of miR155-5P and miR377-3P. Our experimental results verified the inhibitory effect of HO1 on preadipocyte differentiation. In addition, our research confirms that by escaping microRNA inhibitory effects, the HO1 3'UTR short variant produced by APA has a higher level of expression. Thus, the HO1 3'UTR short variant has a stronger inhibitory effect on the preadipocyte differentiation than the HO1 3'UTR long variants in 3T3-L1.

Determinants of stem cell lineage differentiation toward chondrogenesis versus adipogenesis

Adult stem cells, also termed as somatic stem cells, are undifferentiated cells, detected among differentiated cells in a tissue or an organ. Adult stem cells can differentiate toward lineage specific cell types of the tissue or organ in which they reside. They also have the ability to differentiate into mature cells of mesenchymal tissues, such as cartilage, fat and bone. Despite the fact that the balance has been comprehensively scrutinized between adipogenesis and osteogenesis and between chondrogenesis and osteogenesis, few reviews discuss the relationship between chondrogenesis and adipogenesis. In this review, the developmental and transcriptional crosstalk of chondrogenic and adipogenic lineages are briefly explored, followed by elucidation of signaling pathways and external factors guiding lineage determination between chondrogenic and adipogenic differentiation. An in-depth understanding of overlap and discrepancy between these two mesenchymal tissues in lineage differentiation would benefit regeneration of high-quality cartilage tissues and adipose tissues for clinical applications.

Hmox1 promotes osteogenic differentiation at the expense of reduced adipogenic differentiation induced by BMP9 in C3H10T1/2 cells

Mesenchymal stem cells (MSCs) are multipotent progenitors that can differentiate into a variety of cell types under proper stimuli. Bone morphogenetic protein 9 (BMP9) is able to simultaneously induce both adipogenic and osteogenic differentiation of MSCs although the regulatory molecules involved remain to be fully identified and characterized. Heme oxygenase 1 (Hmox1) plays an essential role not only in fat metabolism, but also in bone development. In the present study, we investigated the functional role of Hmox1 in BMP9-induced osteogenic/adipogenic differentiation in MSCs line C3H10T1/2 and probed the possible mechanism involved. We found that BMP9 promoted the endogenous expression of Hmox1 in C3H10T1/2 cells. Overexpression of Hmox1 or cobalt protoporphyrin (CoPP), an inducer of Hmox1, increased BMP9-induced osteogenic differentiation in vitro. Subcutaneous stem cell implantation in nude mice further confirmed that Hmox1 potentiated BMP9-induced ectopic bone formation in vivo. In contrast, Hmox1 reduced BMP9-induced adipogenic differentiation in C3H10T1/2 cells. Although had no obvious effect on BMP9-induced Smad1/5/8 phosphorylation, Hmox1 enhanced phosphorylation of p38, and AKT, while decreased phosphorylation of ERK1/2. Furthermore, Hmox1 increased total β-catenin protein level, and promoted the nuclear translocation of β-catenin in C3H10T1/2 cells. Taken together, our study strongly suggests that Hmox1 is likely to potentiate osteogenic differentiation and yet decrease adipogenic differentiation induced by BMP9 possibly through regulation of multiple signaling pathways.

HMOX1 as a marker of iron excess-induced adipose tissue dysfunction, affecting glucose uptake and respiratory capacity in human adipocytes

AIMS/HYPOTHESIS

Iron excess in adipose tissue is known to promote adipose tissue dysfunction. Here, we aimed to investigate the possible role of haem oxygenase 1 (HMOX1) in iron excess-induced adipose tissue dysfunction.

METHODS

Cross-sectionally, HMOX1 gene expression in subcutaneous and visceral adipose tissue was analysed in two independent cohorts (n = 234 and 40) in relation to obesity. We also evaluated the impact of weight loss (n = 21), weight gain (in rats, n = 20) on HMOX1 mRNA; HMOX1 mRNA levels during human adipocyte differentiation; the effects of inflammation and iron on adipocyte HMOX1; and the effects of HMOX1-induced activity on adipocyte mitochondrial respiratory function, glucose uptake and adipogenesis.

RESULTS

Adipose tissue HMOX1 was increased in obese participants (p = 0.01) and positively associated with obesity-related metabolic disturbances, and markers of iron accumulation, inflammation and oxidative stress (p < 0.01). HMOX1 was negatively correlated with mRNAs related to mitochondrial biogenesis, the insulin signalling pathway and adipogenesis (p < 0.01). These associations were replicated in an independent cohort. Bariatric surgery-induced weight loss led to reduced HMOX1 (0.024 ± 0.010 vs 0.010 ± 0.004 RU, p < 0.0001), whereas in rats, high-fat diet-induced weight gain resulted in increased Hmox1 mRNA levels (0.22 ± 0.15 vs 0.54 ± 0.22 RU, p = 0.005). These changes were in parallel with changes in BMI and adipose tissue markers of iron excess, adipogenesis and inflammation. In human adipocytes, iron excess and inflammation led to increased HMOX1 mRNA levels. HMOX1 induction (by haem arginate [hemin] administration), resulted in a significant reduction of mitochondrial respiratory capacity (including basal respiration and spare respiratory capacity), glucose uptake and adipogenesis in parallel with increased expression of inflammatory- and iron excess-related genes.

CONCLUSIONS/INTERPRETATION

HMOX1 is an important marker of iron excess-induced adipose tissue dysfunction and metabolic disturbances in human obesity.

Linoelaidic acid enhances adipogenic differentiation in adipose tissue-derived stromal cells through suppression of Wnt/β-catenin signaling pathway in vitro

Obesity has become a major health problem which is related with high-trans fatty acids diet. Adipogenic differentiation of adipose tissue-derived stromal cells (ADSCs) plays an important role in the development of adipose tissue. In order to determine the effect of trans fatty acids on adipogenic differentiation in ADSCs, cells were treated with linoelaidic acid, as well as linoleic acid and linolenic acid. We found that linoelaidic acid significantly increased the lipid droplet formation and triglyceride content compared with linoleic acid and linolenic acid. Linoelaidic acid also down-regulated the levels of β-catenin in cells and inhibited the accumulation of β-catenin in cell nuclei. Lithium chloride, an activator of Wnt/β-catenin pathway, antagonized the enhancement of linoelaidic acid on adipogenesis and up-regulated the levels of β-catenin in ADSCs. These results indicated that linoelaidic acid could enhance the adipogenic differentiation in ADSCs in vitro, which is partly due to the suppression of Wnt/β-catenin pathway.