BMP7 Increases UCP1-Dependent and Independent Thermogenesis with a Unique Gene Expression Program in Human Neck Area Derived Adipocytes

White adipocytes contribute to energy storage, accumulating lipid droplets, whereas brown and beige adipocytes mainly function in dissipating energy as heat primarily via the action of uncoupling protein 1 (UCP1). Bone morphogenic protein 7 (BMP7) was shown to drive brown adipocyte differentiation in murine interscapular adipose tissue. Here, we performed global RNA-sequencing and functional assays on adipocytes obtained from subcutaneous (SC) and deep-neck (DN) depots of human neck and differentiated with or without BMP7. We found that BMP7 did not influence differentiation but upregulated browning markers, including UCP1 mRNA and protein in SC and DN derived adipocytes. BMP7 also enhanced mitochondrial DNA content, levels of oxidative phosphorylation complex subunits, along with PGC1α and p-CREB upregulation, and fragmentation of mitochondria. Furthermore, both UCP1-dependent proton leak and UCP1-independent, creatine-driven substrate cycle coupled thermogenesis were augmented upon BMP7 addition. The gene expression analysis also shed light on the possible role of genes unrelated to thermogenesis thus far, including ACAN, CRYAB, and ID1, which were among the highest upregulated ones by BMP7 treatment in both types of adipocytes. Together, our study shows that BMP7 strongly upregulates thermogenesis in human neck area derived adipocytes, along with genes, which might have a supporting role in energy expenditure.

BMP7 increases UCP1-dependent and independent thermogenesis with a unique gene expression program in human neck area derived adipocytes

White adipocytes contribute to energy storage accumulating lipid droplets, whereas brown and beige adipocytes mainly function in dissipating energy as heat primarily via the action of uncoupling protein 1 (UCP1). Bone morphogenic protein 7 (BMP7) has been shown to drive brown adipocyte differentiation in mice. In this study, we have performed global RNA-sequencing and functional assays on adipocytes obtained from subcutaneous (SC) and deep-neck (DN) depots of human neck, and differentiated with or without BMP7. We found that BMP7 did not influence differentiation but upregulated browning markers, including UCP1 mRNA and protein. BMP7 also enhanced mitochondrial DNA content, fragmentation, and levels of oxidative phosphorylation complex subunits along with PGC1α and p-CREB upregulation. Furthermore, both UCP1-dependent proton leak and UCP1-independent, creatine driven substrate cycle coupled thermogenesis were augmented upon BMP7 treatment in SC and DN derived adipocytes. The gene expression analysis shed light also on possible role of genes unrelated to thermogenesis so far, including ACAN, CRYAB, and ID1, which were amongst the highest upregulated ones by BMP7 treatment in both types of adipocytes. Together, our study shows that BMP7 strongly upregulates thermogenesis in human neck area derived adipocytes, along with genes, which might have a supporting role in energy expenditure.

P–212 Mitochondrial DNA content shows a significant association with timing of human embryo development and fertility diagnosis in euploid embryos

Study question Does mitochondrial DNA content (mtDNA) correlate with clinical parameters and embryo morphokinetics using advanced time-lapse technology? Summary answer mtDNA correlated with embryo morphokinetics and the growth trajectory of euploid embryos. Maternal age, anti-mullerian hormone level and fertility diagnosis were significantly associated with mtDNA. What is known already With the push towards single embryo transfers, laboratories are working to improve embryo selection. In addition to conventional microscopy, preimplantation genetic testing and time-lapse microscopy have been utilized to aid in embryo selection. More recently, as mtDNA may represent the energy potential of an embryo, some data have supported the use of mtDNA as an additional tool. Limited studies have suggested that a lower amount of mtDNA is associated with higher rates of implantation and improved embryo quality. Study design, size, duration This is a retrospective chart review. All embryos that underwent preimplantation genetic testing for aneuploidy (PGT-A) between January to December of 2020 were studied. Participants/materials, setting, methods Women undergoing in vitro fertilization (IVF) with intracytoplasmic sperm injection undergoing PGT-A were studied. All patients were from a single academic institution. This study exclusively examined the characteristics of euploid embryos. Mitochondrial DNA content was expressed as a ratio of mtDNA:nDNA (MitoScore). Time-lapse imaging was utilized to evaluate embryo development every 15 minutes in 5–7 focal planes. Chi square test and Spearman correlation analysis were performed with a p-value of < 0.05 considered significant. Main results and the role of chance A total of 494 embryos from 52 women who underwent 58 IVF cycles were cultured to blastocyst and 331 embryos were biopsied for PGT-A evaluation. Of these, 132 embryos were diagnosed as euploid. A moderate positive correlation was found between MitoScore and time to morula, time to blast and time to expanded blast (correlation value 0.54, 0.50 and 0.54, respectively; p < 0.001). Consistent with this trend, day 5 blastocysts had a significantly lower MitoScore values than day 6 blastocysts (20.2 v. 29.2; p < 0.001). When examining all biopsied euploid embryos, no significant association was found between MitoScore, blastocyst maturity, trophectoderm or inner cell mass scores. Our data also demonstrated a positive correlation between MitoScore and maternal age (correlation factor 0.33; p < 0.001). A negative association between MitoScore and serum anti-mullerian hormone levels (correlation factor –0.20; p < 0.021) was also noted. Of particular interest was the significant association between fertility diagnosis and mitochondrial score (p < 0.001). Even amongst euploid embryos, mtDNA content varied widely, potentially reflecting differences in embryo potential and quality. Additionally, the significant difference in MitoScore between that day 5 and day 6 blastocysts may reflect a fundamental difference in cytoplasmic characteristics and requires further study. Limitations, reasons for caution Due to the study cohort of euploid embryos undergoing PGT-A, this study was biased for the selection of high grade embryos. This limited diversity in embryo quality may have masked other potential associations between mitochondrial content and blastocyst quality. Wider implications of the findings: mtDNA may be additional tool aiding in embryo selection as IVF labs work to improve pregnancy rates while minimizing the risks of transferring multiple embryos. To our knowledge, this is the largest study assessing the relationship of mtDNA content of blastocysts and the timing of embryo development using time-lapse imaging. Trial registration number None

Ndufs1 Deficiency Aggravates the Mitochondrial Membrane Potential Dysfunction in Pressure Overload-Induced Myocardial Hypertrophy

Mitochondrial dysfunction has been suggested to be the key factor in the development and progression of cardiac hypertrophy. The onset of mitochondrial dysfunction and the mechanisms underlying the development of cardiac hypertrophy (CH) are incompletely understood. The present study is based on the use of multiple bioinformatics analyses for the organization and analysis of scRNA-seq and microarray datasets from a transverse aortic constriction (TAC) model to examine the potential role of mitochondrial dysfunction in the pathophysiology of CH. The results showed that NADH:ubiquinone oxidoreductase core subunit S1- (Ndufs1-) dependent mitochondrial dysfunction plays a key role in pressure overload-induced CH. Furthermore, in vivo animal studies using a TAC mouse model of CH showed that Ndufs1 expression was significantly downregulated in hypertrophic heart tissue compared to that in normal controls. In an in vitro model of angiotensin II- (Ang II-) induced cardiomyocyte hypertrophy, Ang II treatment significantly downregulated the expression of Ndufs1 in cardiomyocytes. In vitro mechanistic studies showed that Ndufs1 knockdown induced CH; decreased the mitochondrial DNA content, mitochondrial membrane potential (MMP), and mitochondrial mass; and increased the production of mitochondrial reactive oxygen species (ROS) in cardiomyocytes. On the other hand, Ang II treatment upregulated the expression levels of atrial natriuretic peptide, brain natriuretic peptide, and myosin heavy chain beta; decreased the mitochondrial DNA content, MMP, and mitochondrial mass; and increased mitochondrial ROS production in cardiomyocytes. The Ang II-mediated effects were significantly attenuated by overexpression of Ndufs1 in rat cardiomyocytes. In conclusion, our results demonstrate downregulation of Ndufs1 in hypertrophic heart tissue, and the results of mechanistic studies suggest that Ndufs1 deficiency may cause mitochondrial dysfunction in cardiomyocytes, which may be associated with the development and progression of CH.