Journal of molecular endocrinology最新文献

Type 2 diabetes mellitus (DM) is closely associated with cellular senescence (SnC), a state of irreversible cell cycle arrest marked by functional decline. Preventing cellular senescence in already diagnosed DM patients is crucial for limiting disease progression and the onset of co-morbidities. The relationship between oxidative stress, DNA damage, and telomere shortening provides a mechanistic framework for elucidating the role of cellular senescence in the pathogenesis and progression of type 2 DM. This senescence-driven model of metabolic dysfunction not only accounts for impaired β-cell function and insulin resistance but also for the systemic complications observed in DM patients. The accumulation of senescent cells, particularly in metabolically active tissues such as adipose tissue, is increasingly recognised as both a cause and a consequence of the chronic inflammatory environment that characterises diabetes. Evidence from in vitro and preclinical studies highlights the detrimental effects of the senescence-associated secretory phenotype, reinforcing tissue damage through paracrine and autocrine signalling mechanisms. Despite its complexity, approaches targeting the senescent phenotype offer a promising avenue for adjunct therapies. Senotherapeutics, such as senomorphic agents that protect cells from cytotoxic damage and mitigate oxidative stress, can potentially protect against disease onset, whereas senolytic agents have the potential to eliminate senescent cells to limit metabolic disease progression, mitigate complications, and ultimately improve patient outcomes. There is, however, an urgent need to translate the preclinical findings into clinical trials to assess the safety, efficacy, and long-term effects of senotherapeutic agents.

Maturity-onset diabetes of the young (MODY) is a form of monogenic diabetes caused by single-gene mutations. MODY3, the most common subtype, results from mutations in the hepatocyte nuclear factor 1-alpha (HNF1α) gene. HNF1α is a transcription factor essential for pancreatic β-cell function and insulin production. Clinically, β-cells in MODY3 patients generally retain intact sulfonylurea receptor function, making sulfonylureas the preferred treatment. However, a novel loss-of-function variant, HNF1α-Q125ter, has been shown to induce sulfonylurea insensitivity in MODY3 patients. This study aimed to investigate the role and mechanism of HNF1α-Q125ter-mediated mitochondrial dysfunction and impaired mitophagy in new variant-induced β-cell dysfunction. Mitophagy-related protein and transcription levels were analysed by Western blotting and reverse transcription-quantitative PCR (RT-qPCR). Mitochondrial morphology was examined by transmission electron microscopy. Ins-1 cells were transfected with overexpression constructs for HNF1α-Q125ter or short hairpin RNA targeting HNF1a (shHNF1α) to assess its effects on mitochondrial function and mitophagy. Ins-1 cells expressing HNF1α-Q125ter showed decreased mitochondrial number, oxygen consumption, and energy metabolism. Correspondingly, mitochondrial morphology was damaged in an hnf1a+/- zebrafish model. HNF1α-Q125ter also inhibited mitophagy by suppressing the mRNA expression of PTEN-induced kinase 1 (PINK1), pyruvate dehydrogenase E1 subunit α1 (PDHA1), and Parkin RBR E3 ubiquitin-protein ligase (Parkin). Mechanistically, HNF1α-Q125ter impaired autophagy by downregulating phosphorylated mammalian target of rapamycin (p-mTOR) (Ser2448) and phosphorylated-70 kDa ribosomal protein S6 kinase (p-p70S6K) (Thr389). In conclusion, our findings suggest that HNF1α-Q125ter induces mitophagy dysfunction by suppressing the p-mTOR(ser2448)/p-p70S6K(Thr389) signalling pathway, providing novel insights into the mechanisms underlying sulfonylurea insensitivity in patients with this variant.

Insulin resistance is often characterized as the factor that contributes to the emergence of metabolic diseases. Hepatic microRNAs (miRNAs) played critical roles in the development of metabolic-associated steatotic liver disease (MASLD) and insulin resistance. To investigate the effects of hepatic miR-411-5p in regulating insulin resistance, the present study utilized primary mouse hepatocytes and mice with MASLD. Suppression of miR-411-5p decreased hepatocyte glycogen production and phosphorylation of AKT, but miR-411-5p mimic improved insulin sensitivity. Mechanistically, 3'-UTR of transcription factor Sp2 was one of the binding sites of miR-411-5p. Treatment of miR-411-5p mimic suppressed the Sp2 mRNA and protein levels, enhancing the insulin signaling activity in the primary mouse hepatocytes. Hepatocyte-specific overexpression of Sp2 induced hepatic lipid accumulation and activation of related metabolic pathways. In contrast, inhibition of miR-411-5p reversely upregulated the expression of Sp2 and exaggerated insulin resistance in primary hepatocytes and the mouse model. Similarly, miR-411-5p mimic decreased obesity-induced hyperinsulinemia, glucose intolerance, insulin intolerance, and pyruvate intolerance. Furthermore, the parameters of MASLD, including lipid deposits, inflammation, and fibrosis, were improved after miR-411-5p replenishment, but co-administration with adeno-associated virus (AAV)-Sp2 abolished these benefits in the obese mouse model. Taken together, these findings demonstrated that Sp2-dependent miR-411-5p action regulates insulin resistance and MASLD, which provides a therapeutic approach toward resolving insulin resistance.

Estrogens are steroid hormones that regulate antioxidant and mitochondrial bioenergetic metabolism in addition to activating nuclear genomic pathways. Concentrating these effects within the mitochondria is a novel strategy for ameliorating mitochondrial dysfunction, which is characteristic of cancer, metabolic, and neurodegenerative diseases. The use of synthetic mitochondria-targeted estrogens containing a triphenylphosphonium group may provide a basis for improving mitochondrial function in these conditions. Here, we evaluate the effects of two compounds, one derived from 17β-estradiol (mitoE2) and the other from 17α-ethinylestradiol (mitoEE2), on cell viability in MCF-7 and CCD-1112Sk cells. We further examine their influence on the activities of superoxide dismutase (MnSOD), citrate synthase (CS), cytochrome c oxidase (COX), and ATP synthase, as well as on the glycolytic reserve and cellular respiration. In both cellular models, cell viability assays indicated that mitoE2 was well tolerated below 500 nM, while mitoEE2 allowed treatments up to 100 nM for up to 24 h. We found that the molecules act differently on enzymatic targets. Exposure of MCF-7 cells to mitoE2 resulted in reduced MnSOD activity. Pretreatment with mitoE2 or mitoEE2 restored the viability of MCF-7 cells exposed to H2O2-induced oxidative damage to levels comparable to untreated controls. In addition, mitoEE2 increased the activities of CS and COX. Both mitochondria-targeted estrogens increased glycolytic reserve and mitochondrial respiration, as determined by extracellular flux assays. Overall, these findings suggest that the antioxidant and bioenergetic effects observed encourage further investigation into their potential as therapeutic strategies for conditions linked to mitochondrial dysfunction.

Orbital fibroblast proliferation and activation contribute to the development of thyroid-associated ophthalmopathy (TAO). In this study, nuclear receptor subfamily 4 group A member 3 (NR4A3) was predicted to play a role in TAO based on bioinformatics analysis. Validation of NR4A3 expression in human TAO orbital samples confirmed its elevated levels compared to normal controls. In vitro studies demonstrated that transforming growth factor beta 1 (TGF-β1)-induced NR4A3 expression in human TAO orbital fibroblasts (OFs) enhanced cell viability, DNA synthesis, and fibrotic marker expression. Conversely, NR4A3 knockdown inhibited these fibrotic responses, suggesting a pro-fibrotic role for NR4A3 in TAO. In vivo experiments further validated these findings, with NR4A3 knockdown in a TAO mouse model leading to reduced pathological injury and fibrosis in orbital tissues. In addition, NR4A3 knockdown decreased the expression of fibrotic markers in the orbital tissues of TAO mice, corroborating the in vitro results. Finally, NR4A3 was shown to modulate the nuclear factor kappa B (NF-κB) pathway, which is activated in TAO. NR4A3 overexpression enhanced, while its knockdown suppressed, NF-κB activation in both human TAO OFs and orbital tissues from TAO mice. These findings suggest that NR4A3 promotes TAO progression through its pro-fibrotic effects and activation of NF-κB signaling, highlighting its potential as a therapeutic target for TAO. Collectively, NR4A3 plays a pivotal regulatory role in both fibroblast proliferation and the fibrotic response in TAO, acting through mechanisms involving the NF-κB signaling pathway. Its ability to enhance TGF-β1-induced changes and activate NF-κB underscores its potential as a key therapeutic target for addressing the complex pathophysiology of TAO.

Approximately 10% of children born small for gestational age (SGA) fail to achieve catch-up growth, resulting in persistent short stature and eligibility for growth hormone (GH) therapy under established guidelines. Pathogenic variants in insulin-like growth factor 1 receptor (IGF1R) are associated with SGA, syndromic short stature, neurocognitive impairment, and variable responsiveness to GH therapy. This study aimed to characterize the clinical phenotype and elucidate the molecular mechanism underlying a rare intronic variant in IGF1R identified in an affected family. Here, we performed whole-exome sequencing (WES) on a single individual, followed by segregation studies in the family and Sanger sequencing. cDNA studies were pursued to evaluate mis-spliced transcripts. WES of the proband's affected mother revealed a rare heterozygous variant in IGF1R (NM_000875.5): c.3722+5G>A. Sanger sequencing confirmed segregation of the variant with the affected status in available family members. cDNA analysis showed that the variant results in intronic retention of 134 nucleotides immediately following the penultimate exon of IGF1R. This leads to a frameshift and introduction of a premature truncation codon, supporting the classification of the variant as likely pathogenic. Our study highlights the utility of genetic testing in SGA children with persistent short stature. By characterizing a novel IGF1R intronic variant causing aberrant splicing, we expand the understanding of its clinical spectrum and molecular underpinning. The findings underscore the importance of molecular diagnostics in unexplained short stature and neurodevelopmental disorders and may inform future therapeutic strategies targeting the IGF1R signaling.

While pregnancy is known to be an inflammatory condition, preeclampsia (PE) is associated with higher chemokines and pro-inflammatory cytokines and higher Th1/Th2 and Th17/Treg ratios. Since the uteroplacental space can secrete cytokines, including TNF and IL1B, a common assumption is that the proinflammatory immune cell profile of Th1 and Th17 cells dominating over Th2 and Treg cells begins in that space. To date, a possible role for endothelium in this initiation process has not been considered. Nonetheless, recent publications show that endothelium can become immunomodulatory on exposure to TNF and IL1B, and in systemic hypertension, endothelium has been shown to exist as multiple cell subtypes. We have recently shown that uterine artery endothelial cells from late-pregnant sheep (P-UAEC) treated with TNF alone secrete many of the chemokines and cytokines further elevated in PE subjects. Herein, we show that P-UAEC also exist in multiple subtypes with distinct chemokine and cytokine secretory and immunomodulatory properties. The five subtypes are differentially regulated by TNF-alpha (TNF) and IL1-beta (IL1B), which may favor subtype-specific binding and interaction with distinct classes of Th cells, and an altered ability to respond to Th-secreted cytokines (such as IL17 and IL10). Thus, our data demonstrate the possibility that certain endothelial cell subtypes can be pushed to express immunomodulatory proteins by early exposure to increases in TNF or IL1B of immune cell, trophoblast, and decidual origin. This, in turn, begs the question of whether such endothelial changes could contribute to subsequent immune disturbances seen at the time of clinical presentation.

The glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) are important incretin receptors that are therapeutic targets for the treatment of type 2 diabetes and obesity. This study extensively characterised the metabolic phenotype of mice with global deletion of either the GLP-1R or GIPR side by side under identical conditions. Age-matched male wild-type (WT) C57Bl6NTac, GLP-1RKO or GIPRKO mice were placed on a high-fat or chow diet for 12 weeks, and a range of in vivo (weight gain, food intake, glucose tolerance, insulin tolerance, and whole-body energy metabolism) and ex vivo (white adipocyte lipolysis, brown adipose tissue and liver mitochondrial function, adipocyte and islet size, and hepatic steatosis) parameters were measured. While both WT and GLP-1RKO mice gained weight similarly on a HFD, obese high-fat-fed GLP-1RKO mice had altered glucose and insulin tolerance, and exhibited hepatic steatosis, highlighting the physiological importance of the GLP-1R in the regulation of blood glucose and lipid homoeostasis. In contrast, GIPRKO mice were partially resistant to diet-induced obesity compared to the WT mice, which was associated with a small reduction in food intake and intact epididymal and subcutaneous white adipocyte β-adrenoceptor-mediated lipolysis. Similarly, WT mice treated with a GIPR antagonist prevented weight gain due to a reduction in food intake on a HFD. These findings provide further support that the GLP-1R is important for normal glycaemic control, whereas the GIPR may play a role in the regulation of body weight.

Bone marrow stromal cells (BMSCs) play an important role in bone regeneration, but their functional activity is affected by oxidative stress, which is a key pathological feature of osteoporosis. The aim of this study was to investigate the effects of capsaicin on the proliferation and differentiation of BMSCs under oxidative stress. We assessed cell viability and osteogenic potential of capsaicin in promoting BMSC survival and enhancing osteogenic capacity under oxidative stress by cell counting kit-8 (CCK-8), reactive oxygen species fluorescence staining, alkaline phosphatase (ALP) staining, Alizarin Red S (ARS) staining, Western blot (WB), and real-time PCR (RT-PCR). Our results indicate that capsaicin improves cell viability, antioxidant capacity, and osteogenic differentiation in rat BMSCs treated with hydrogen peroxide (H2O2). In addition, immunohistochemistry (IHC) analysis revealed that the surface of BMSCs expressed the capsaicin receptor transient receptor potential vanilloid protein 1 (TRPV1). More importantly, capsaicin increased Ca2+ influx and autophagy and inhibited phosphorylation of the PI3K/AKT/mTOR signaling pathway. In conclusion, capsaicin protects BMSC function during oxidative stress, possibly through inducing TRPV1-mediated Ca2+ influx and PI3K/AKT/mTOR-activated autophagy. The results suggest the potential of capsaicin as a therapeutic agent for osteoporosis.