Epigenetic suppression of creatine kinase B in adipocytes links endoplasmic reticulum stress to obesity-associated inflammation

Creation of Genetically Modified Adipocytes for Tissue Engineering: Creatine Kinase B Overexpression Leads to Stimulated Glucose Uptake and Mitochondrial Potential Growth, but Lowered Lipid Synthesis

BACKGROUND

The global burden of obesity and type 2 diabetes mellitus is a significant contributor to mortality and disability in the modern world. In this regard, the modification of adipocyte metabolism has been identified as a promising approach to develop new genetic and cellular engineering therapeutics. In this study, we activate the expression of creatine kinase B (CKB), a key enzyme of a non-canonical futile cycle and the regulator of energy storage, to promote catabolic processes in mature adipocytes.

METHODS

The protein-coding sequence of CKB was amplified by PCR from Mus musculus brain mRNA. Lentiviral transduction was used to transfer the CKB sequence into mature adipocytes. Adipocyte metabolism was analyzed by radioisotope monitoring of labeled [3H]-2-deoxyglucose and [14C]-glucose. Confocal microscopy was applied to estimate lipid droplets morphology (BODIPY493/503 dye), mitochondrial membrane potential (JC-1 dye), and thermogenesis (ERthermAC dye).

RESULTS

After lentiviral delivery of the CKB-coding sequence, CKB mRNA level increased 75-fold and protein expression fivefold. CKB overexpression does not cause significant changes in lipid droplet morphology. Despite this, enhanced glucose uptake and reduced lipid synthesis under adrenergic stimulation are detected during CKB overexpression. CKB causes an increase in mitochondrial potential with no effect on thermogenesis in adipocytes.

CONCLUSIONS

In this study, we have shown that CKB overexpression in mature adipocytes allows us to obtain adipocytes with high glucose uptake, potency of ATP synthesis, and suppressed lipogenesis. These genetically modified cells may potentially exhibit a favorable metabolic effect in the context of excessive nutrient utilization.

Phosphatase and tensin homolog deficiency induces M2 macrophage polarization by promoting glycolytic activity in endometrial stromal cells

Endometriosis is a common gynecological disorder, whose pathogenesis remains incompletely understood. Macrophages, a key type of immune cell, are pivotal in the context of endometriosis. This study seeks to explore the interactions between endometriotic cells and macrophages. Quantitative real-time PCR (qRT-PCR) and Western blot experiments were employed to detect phosphatase and tensin homolog (PTEN) expression. Glucose consumption, lactate production, extracellular acidification rate, and oxygen consumption rate levels were used to assess cellular glycolytic capacity. The interaction between conditioned media from ectopic endometrial stromal cells (EESCs) and macrophages was investigated through co-culture experiments. The expression of M2 macrophage marker proteins and inflammatory factors was detected via qRT-PCR, immunofluorescence staining, and enzyme-linked immunosorbent assay. Cellular functions were evaluated using Cell Counting Kit-8, 5-Ethynyl-2'-deoxyuridine (EdU), and wound healing assays. We found that PTEN deficiency promoted the glycolytic activity of EESCs. Simultaneously, it significantly promoted the macrophages' polarization toward the M2 phenotype, demonstrated by increased expression of M2 markers (differentiation 206 (CD206), CD163, and (C-C motif) ligand 22 (CCL22)). Further studies revealed that PTEN-deficient EESCs increased the level of CCL2 via promoting glycolytic activity, which was reversed by glycolytic inhibitor. Moreover, lactate and conditioned media from overexpressed CCL2 EESCs facilitated M2 polarization of macrophages, while 2-deoxy-d-glucose reversed the promoting effect. Furthermore, lactate-facilitated macrophages promoted the proliferation and migration abilities of EESCs. PTEN deficiency induces M2 macrophage polarization by promoting glycolytic activity in EESCs, which deepens the knowledge of the pathophysiology of endometriosis and provides novel insights into its treatment.