Semaglutide 6-months therapy of type 2 diabetes mellitus restores adipose progenitors potential to develop metabolically active adipocytes

BACKGROUND

Nowadays type 2 diabetes mellitus (T2DM) leads to population mortality growth. Today glucagon-like peptide type 1 receptor agonists (GLP-1 RA) are one of the most promising glucose-lowered drugs with anorexigenic and cardioprotective effects. The present study aims to determine the effects of GLP-1 RA semaglutide 6-month therapy on T2DM patient metabolic parameters and adipose progenitor cell health.

METHODS

T2DM patients (N = 8) underwent clinical characterization and subcutaneous fat biopsy at start point and after semaglutide 6-month therapy. Adipose-derived stem cells (ADSC) were isolated by enzymatic method. Cell proliferation analysis was performed by MTT and immunocytochemistry. White and beige adipogenesis was analyzed by BODIPY493/503 staining and confocal microscopy. Adipocyte's metabolic properties were estimated by 3H- and 14C-based metabolic assays. Thermogenesis analysis was performed by ERthermAC staining and confocal microscopy. Protein markers were assessed by Western blotting.

RESULTS

Semaglutide 6-month therapy demonstrated significant anorexigenic and glucose-lowering effects. However, insulin sensitivity (HOMA-IR and M-index) was unchanged after therapy. Semaglutide 6-month therapy increased ADSC proliferation and white and beige adipogenesis. Moreover, lipid droplets fragmentation was observed in beige adipocytes. Both white and beige adipocytes after semaglutide therapy demonstrated 2-3 fold growth of glucose uptake without changes in insulin sensitivity. Newly formed white adipocytes demonstrated glucose utilization for active ATP synthesis, whereas beige adipocytes for canonical thermogenesis.

CONCLUSIONS

Our study has revealed that semaglutide 6-month therapy has not only systemic anorexigenic effects, but can markedly improve adipose tissue health. We have demonstrated critical restoration of ADSC renewal functions, which potentially can be involved in semaglutide based weight loss.

Risk assessment of change in respiratory gas concentrations by native culturable bacteria in the air of sulfide ore mines

Sulfide ores are extracted from mines at considerable depths, that having unique a physical and chemical environment. On the one hand, physical, chemical, and biological processes taken place in the rocks produce this environment; on the other hand, they form unique bacterial communities. The aim of this study was to study the native culturable aerobic bacteria present in the sulfide ores of the deposits located in the Krasnoyarsk Territory (Russia) and evaluate their activity in relation to respiratory gases (oxygen and carbon dioxide) present in air. The results of the study established that the culturable bacteria present in the sulfide ore of the N1 deposit were related to genera Bacillus and Paenibacillus (class Bacilli), genera Citricoccus, Micrococcus, Brachybacterium, Microcella, Dietzia, and Rhodococcus (class Actinomycetia) and genera Paracoccus and Pseudomonas (class Proteobacteria). The culturable bacteria of the N2 sulfide ore deposit were represented by genera Bacillus, Oceanobacillus, Alicyclobacillus (class Bacilli) and genera Micrococcus and Agromyces (class Actinomycetia). The N2 deposit community contained the strain Nor9-1, which showed a high level of similarity with the Alicyclobacillus aeris ZJ-6 iron-/sulfur-oxidizing bacterium. The model systems showed a strong correlation (r² = 0.91-0.97) between the growth of the bacterial communities of the studied ores and changes in the concentrations of oxygen and carbon dioxide in the model atmosphere. Under the ecological optimum (specific growth rate of the culture constituting 0.519 d^-1) in 7 d, oxygen decreased to 0.34-1.48% and carbon dioxide increased to 7.44-14.88%. Under the ecological pessimum (restricted available organic carbon), given the predominant development of the chemolithotrophic group of bacteria (specific growth rate of 0.045 d^-1), changes in the respiratory gas concentrations constituted 0.9-2.7% of O₂ and 0.06-0.16% of CO₂. A relationship was established between the specific rate of O₂/CO₂ loss and specific growth rate of the bacterial communities. Thus, for the first time, indigenous cultivated aerobic bacteria of sulfide ores collected from the deposits of the Krasnoyarsk Territory were studied, and their effects on oxygen and carbon dioxide contents in the atmosphere of closed model systems were examined.

P4406New hypothesis of the insulin resistance development: role of adipose-derived stem cell proliferation and adipogenesis

Background

Obesity, remaining a topical issue of modern medicine, leads to development of latent inflammation and insulin resistance in adipose tissue with subsequent development of type 2 diabetes mellitus (T2DM). Among patients with obesity, patients with obesity and normal glucose tolerance (NGT) are often encountered. In our study we have tested the hypothesis that low proliferative potential of adipose derived stromal cells (ADSC) associates with reduced formation of new fat depots, excess accumulation of fat in the functional adipocytes and their hypertrophy, resulting in fat inflammation and insulin resistance.

Methods

We screened two groups of obese patients with or without T2DM, matched for BMI, age, and duration of obesity to test the hypothesis that hypertrophy and decreased renewal of adipocytes may underlie transition from obesity to T2DM. All patients were matched for carbohydrate metabolism (fasting blood glucose level, glycated hemoglobin, HOMA-IR index and M-index). The subcutaneous and omental fat tissue biopsies were obtained during bariatric surgery from obese individuals with or without T2DM. The morphology and immunophenotype of subcutaneous and omental fat was assessed in frozen tissue sections. ADSC were isolated from both types of fat tissue biopsies and screened for morphology, proliferative potential and inflammatory status.

Results

The non-diabetic patients had normal carbohydratemetabolism andmoderate insulin resistancemeasured byHOMA-IR and hyperinsulinemic clamp (M-index),while T2DM patientswere extremely insulin resistant by both indexes. The average size of diabetic adipocytes was higher than that of non-diabetic in both subcutaneous and omental fat tissues, indicating adipocyte hypertrophy in T2DM. We have shown that ADSC from T2DM patients had significantly higher level of inflammation. According to measurement of p62 expression and LC3 modification we can say that ADSC from T2DM patients have less autophagy level compare with ADSC from NGT patients. Immunohistochemistry have shown that patients with T2DM have much more infiltration of CD68+-cells in subcutaneous and omental adipose tissue and immunophenotype (balance of M1-M2 macrophages) of adipose tissue at this patients shift toward inflammatory state.

Conclusion

These results suggest that decreased proliferation and increased hypertrophy of diabetic ADSC may lead to reduced insulin sensitivity via increased inflammation mediated by M1-macrophages and JNK1/2 pathway.

Acknowledgement/Funding

This work was supported by RSF grant #17-15-01435

Low proliferative potential of adipose-derived stromal cells associates with hypertrophy and inflammation in subcutaneous and omental adipose tissue of patients with type 2 diabetes mellitus

BACKGROUND

Obesity and type 2 diabetes mellitus (T2DM) are among the most important morbidity factors. In this study we tested the hypothesis that low proliferative potential of adipose derived stromal cells (ADSC) associates with reduced formation of new fat depots, excess accumulation of fat in the functional adipocytes and their hypertrophy, resulting in fat inflammation and insulin resistance.

METHODS

We screened two groups of obese patients with or without T2DM, matched for BMI, age, and duration of obesity to test the hypothesis that hypertrophy and decreased renewal of adipocytes may underlie transition from obesity to T2DM. All patients were matched for carbohydrate metabolism (fasting blood glucose level, glycated hemoglobin, HOMA-IR index and M-index). The subcutaneous and omental fat tissue biopsies were obtained during bariatric surgery from obese individuals with or without T2DM. The morphology and immunophenotype of subcutaneous and omental fat was assessed in frozen tissue sections. ADSC were isolated from both types of fat tissue biopsies and screened for morphology, proliferative potential and inflammatory status.

RESULTS

The non-diabetic patients had normal carbohydrate metabolism and moderate insulin resistance measured by HOMA-IR and hyperinsulinemic clamp (M-index), while T2DM patients were extremely insulin resistant by both indexes. The average size of diabetic adipocytes was higher than that of non-diabetic in both subcutaneous and omental fat tissues, indicating adipocyte hypertrophy in T2DM. Both these tissues contained higher level of macrophage infiltration and increased M1-like to M2-like ratio of macrophage subpopulations, suggesting increased fat inflammation in T2DM. This was confirmed by increased activatory phosphorylation of stress-induced JNK1/2 in diabetic ADSC.

CONCLUSION

These results suggest that blunted proliferation and increased hypertrophy of diabetic ADSC may lead to reduced insulin sensitivity via increased inflammation mediated by M1 macrophages and JNK1/2 pathway.

Role of MicroRNAs in the Regulation of Subcutaneous White Adipose Tissue in Individuals With Obesity and Without Type 2 Diabetes

Obesity is a high-risk factor for such comorbidities as cardiovascular disease, several types of cancer, and type 2 diabetes; however not all individuals with obesity have such complications. Approximately 20% of individuals with obesity are metabolically healthy. This study focused on differences between obese individuals with and without type 2 diabetes (T2D+ and T2D-, respectively) on the transcriptome level. Subjects included were 35 T2D- patients with obesity and 35 T2D+ patients with obesity with the same body mass index (BMI). The study was based on the transcription analysis of mRNA and microRNAs (miRs) by RNAseq. In the first step, we performed RNAseq of miRs, in the second step, we analyzed only those mRNA, which appeared targets for significant miRs from the first step. All RNAseq results were validated by qPCR. There were seven miRs differently expressed with adjusted p-value <0.1, which were confirmed by qPCR. Five among them: miR-204-5p, miR125b-5p, miR-125a-5p, miR320a, miR-99b-were upregulated in T2D+ patients with obesity, while only two miRs, miR-23b-3p, and miR197-3p, were increased in T2D- patients with obesity. These seven miRs target two groups of genes: matrix metalloproteinases and TGFβ signal pathway genes. According to the results of transcriptome analysis, the main difference between T2D+ and T2D- patients with obesity was in adipogenesis and fibrosis regulation by matrix metalloproteinases and SMAD4-RUNX2 signal cascade. Based on the data about transcription profiles of both groups, we suggested that the process of fibrosis in T2D+ patients with obesity is more pronounced than in T2D- patients with obesity.

Association of the interferon-β gene with pericentromeric heterochromatin is dynamically regulated during virus infection through a YY1-dependent mechanism

Nuclear architecture as well as gene nuclear positioning can modulate gene expression. In this work, we have analyzed the nuclear position of the interferon-β (IFN-β) locus, responsible for the establishment of the innate antiviral response, with respect to pericentromeric heterochromatin (PCH) in correlation with virus-induced IFN-β gene expression. Experiments were carried out in two different cell types either non-infected (NI) or during the time course of three different viral infections. In NI cells, we showed a monoallelic IFN-β promoter association with PCH that strongly decreased after viral infection. Dissociation of the IFN-β locus away from these repressive regions preceded strong promoter transcriptional activation and was reversible within 12 h after infection. No dissociation was observed after infection with a virus that abnormally maintained the IFN-β gene in a repressed state. Dissociation induced after virus infection specifically targeted the IFN-β locus without affecting the general structure and nuclear distribution of PCH clusters. Using cell lines stably transfected with wild-type or mutated IFN-β promoters, we identified the proximal region of the IFN-β promoter containing YY1 DNA-binding sites as the region regulating IFN-β promoter association with PCH before as well as during virus infection.

RAP80-directed tuning of BRCA1 homologous recombination function at ionizing radiation-induced nuclear foci

In response to DNA double-strand breaks (DSBs), BRCA1 forms biochemically distinct complexes with certain other DNA damage response proteins. These structures, some of which are required for homologous recombination (HR)-type DSB repair, concentrate at distinct nuclear foci that demarcate sites of genome breakage. Polyubiquitin binding by one of these structures, the RAP80/BRCA1 complex, is required for efficient BRCA1 focal recruitment, but the relationship of this process to the execution of HR has been unclear. We found that this complex actively suppresses otherwise exaggerated, BRCA1-driven HR. By controlling the kinetics by which other BRCA1-interacting proteins that promote HR concentrate together with BRCA1 in nuclear foci, RAP80/BRCA1 complexes suppress excessive DSB end processing, HR-type DSB repair, and overt chromosomal instability. Since chromosomal instability emerges when BRCA1 HR function is either unbridled or absent, active tuning of BRCA1 activity, executed in nuclear foci, is important to genome integrity maintenance.

Further evidence for BRCA1 communication with the inactive X chromosome

BRCA1, a breast and ovarian cancer-suppressor gene, exerts tumor-suppressing functions that appear to be associated, at least in part, with its DNA repair, checkpoint, and mitotic regulatory activities. Earlier work from our laboratory also suggested an ability of BRCA1 to communicate with the inactive X chromosome (Xi) in female somatic cells (Ganesan et al., 2002). Xiao et al. (2007) (this issue of Cell) have challenged this conclusion. Here we discuss recently published data from our laboratory and others and present new results that, together, provide further support for a role of BRCA1 in the regulation of XIST concentration on Xi in somatic cells.

How is epigenetic information on chromatin inherited after DNA replication?

Although most somatic cells have identical genetic information, gene expression profiles are quite distinct in each cell type. The gene expression profiles are considered to be determined mainly by chromatin-encoded epigenetic information that includes histone modifications, histone variants, and factors such as HP1 and polycomb group proteins that organize higher-ordered chromatin structures. To gain insights into how such epigenetic information on chromatin is inherited on daughter DNA strands after DNA replication, we have purified the preassembled form of histone H3 by immunoaffinity purification. The histone H3 complex contains the two histone H3-H4 chaperones CAF1 and ASF1. Surprisingly, the H3 complex also contains a pair of H3-H4 dimers. This observation is striking because histones H3-H4 are known to exist as tetramers in solution. Since histones H3-H4 in the predeposition complex exist as a dimer, this raises the possibility that the H3-H4 dimer in the complex pairs with a parental H3-H4 dimer, assembling the de novo-synthesized and parental H3-H4 dimers in the same nucleosome. Based on these results, we propose a semi-conservative model of nucleosome duplication, which allows for segregation of parental H3-H4 dimers with encoded epigenetic information evenly to daughter DNA strands.

Tau protein binds to pericentromeric DNA: a putative role for nuclear tau in nucleolar organization

The microtubule-associated tau protein participates in the organization and integrity of the neuronal cytoskeleton. A nuclear form of tau has been described in neuronal and non-neuronal cells, which displays a nucleolar localization during interphase but is associated with nucleolar-organizing regions in mitotic cells. In the present study, based on immunofluorescence, immuno-FISH and confocal microscopy, we show that nuclear tau is mainly present at the internal periphery of nucleoli, partially colocalizing with the nucleolar protein nucleolin and human AT-rich alpha-satellite DNA sequences organized as constitutive heterochromatin. By using gel retardation, we demonstrate that tau not only colocalizes with, but also specifically binds to, AT-rich satellite DNA sequences apparently through the recognition of AT-rich DNA stretches. Here we propose a functional role for nuclear tau in relation to the nucleolar organization and/or heterochromatinization of a portion of RNA genes. Since nuclear tau has also been found in neurons from patients with Alzheimer's disease (AD), aberrant nuclear tau could affect the nucleolar organization during the course of AD. We discuss nucleolar tau associated with AT-rich alpha-satellite DNA sequences as a potential molecular link between trisomy 21 and AD.

Transcription factor YY1 binds to the murine beta interferon promoter and regulates its transcriptional capacity with a dual activator/repressor role

The induction of the beta interferon (IFN-beta) gene constitutes one of the first responses of the cell to virus infection. Its regulation is achieved through an intricate combination of virus-induced binding of transcription factors and local chromatin remodeling. In this work, we demonstrate that transcription factor YY1, known to interact with histone deacetylases (HDAC) and histone acetyltransferases, has a dual activator/repressor role during the regulation of the IFN-beta promoter activity. We show that YY1 specifically binds in vitro and in vivo to the murine IFN-beta promoter at positions -90 and -122. Overexpression of YY1 strongly repressed the transcriptional capacity of a stably integrated IFN-beta promoter fused to a chloramphenicol acetyltransferase reporter gene as well as the endogenous IFN activity of murine L929 cells via an HDAC activity. Stably integrated IFN-beta promoters mutated at the -90 site were no longer repressed by YY1, could no longer be activated by trichostatin A, displayed a retarded postinduction turn off, and a reduced virus-induced activity. Introduction of a mutation at the -122 site did not affect YY1-induced repression, but promoters with this mutation displayed a reduced virus-induced activity. Stably integrated full-length promoters (from position -330 to +20) mutated at both YY1-binding sites displayed extremely reduced promoter activities. We conclude that YY1 has a dual activator/repressor role on IFN-beta promoter activity depending on its binding site and time after infection.

Inhibition of histone deacetylation induces constitutive derepression of the beta interferon promoter and confers antiviral activity

The induction of alpha/beta interferon (IFN-alpha/beta) genes constitutes one of the first responses of the cell to virus infection. The IFN-beta gene is constitutively repressed in uninfected cells and is transiently activated after virus infection. In this work we demonstrate that histone deacetylation regulates the silent state of the murine IFN-beta gene. Using chromatin immunoprecipitation (ChIP) assays, we show a direct in vivo correlation between the transcriptionally silent state and a state of hypoacetylation of histone H4 on the IFN-beta promoter region. Trichostatin A (TSA), a specific inhibitor of histone deacetylases, induced strong, constitutive derepression of the murine IFN-beta promoter stably integrated into a chromatin context, as well as the hyperacetylation of histone H4, without requiring de novo protein synthesis. We also show in this work that TSA treatment strongly enhances the endogenous IFN level and confers an antiviral state to murine fibroblastic L929 cells. Inhibition of histone deacetylation with TSA protected the cells against the lost of viability induced by vesicular stomatitis virus (VSV) and inhibited VSV multiplication. Using antibodies neutralizing IFN-alpha/beta, we show that the antiviral state induced by TSA is due to TSA-induced IFN production. The demonstration of the predominant role of histone deacetylation during the regulation of the constitutive repressed state of the IFN-beta promoter constitutes an interesting advance on the understanding of the negative regulation of this gene and opens up the possibility of new therapeutic perspectives.

Epithelial and fibroblastoid cells contain numerous cell-type specific putative microtubule-regulating proteins, among which are ezrin and fodrin

Upon cell junction formation, the microtubules of polarizing epithelial cells become reorganized by unknown signaling mechanisms and regulating proteins. Microtubule-associated (MAPs) and other types of proteins are likely to be involved in this process, but most of these are unknown. Such proteins are called here collectively microtubule-regulating proteins (MRPs). As a first step towards their characterization, we used co-sedimentation of cytosolic proteins of MDCK cells and A72, a dog fibroblastoid line, with an excess of taxol-stabilized MTs, to obtain a cell fraction enriched in putative MRPs ("MRPs"). Additional tests have led to the inventory of around 40 "MRPs" among the 80 proteins present in the microtubule pellet. We also found that "MRPs" are recovered in higher amounts from MDCK cytosol, and that half of these are cell-type specific. These results corroborate data from yeast cells and insect eggs, and show that in mammalian somatic cells too, a large number of proteins seems to be involved in microtubule regulation, and that different cell types use a specific set of MRPs. "MRPs" found in both cell types are the intermediate chain of cytoplasmic dynein, Arp1, the major subunit of the dynactin complex, and CLIP-170. Two MDCK-specific "MRPs" were identified as the actin-binding proteins ezrin and alpha-fodrin. These results are discussed with regard to a possible involvement of ezrin and fodrin in morphogenetic interactions of microtubules with the membrane cytoskeleton in polarizing epithelia upon junction formation.