PEGylated AdipoRon derivatives improve glucose and lipid metabolism under insulinopenic and high-fat diet conditions.

The pleiotropic actions of adiponectin in improving cell survival and metabolism have motivated the development of small-molecule therapeutic agents for treating diabetes and lipotoxicity. AdipoRon is a synthetic agonist of the adiponectin receptors, yet is limited by its poor solubility and bioavailability. In this work, we expand on the protective effects of AdipoRon in pancreatic ß-cells and examine how structural modifications could affect the activity, pharmacokinetics, and bioavailability of this small molecule. We describe a series of AdipoRon analogs containing amphiphilic ethylene glycol (PEG) chains. Among these, AdipoRonPEG5 induced pleiotropic effects in mice under insulinopenic and high-fat diet (HFD) conditions. While both AdipoRon and AdipoRonPEG5 substantially attenuate palmitate-induced lipotoxicity in INS-1 cells, only AdipoRonPEG5 treatment is accompanied by a significant reduction in cytotoxic ceramides. In vivo, AdipoRonPEG5 can substantially reduce pancreatic, hepatic, and serum ceramide species, with a concomitant increase in the corresponding sphingoid bases and improves insulin sensitivity of mice under HFD feeding conditions. Furthermore, hyperglycemia in streptozotocin (STZ)-induced insulinopenic adiponectin-null mice is also attenuated upon AdipoRonPEG5 treatment. Our results suggest that AdipoRonPEG5 is more effective in reducing ceramides and dihydroceramides in the liver of HFD-fed mice than AdipoRon, consistent with its potent activity in activating ceramidase in vitro in INS-1 cells. Additionally, these results indicate that the beneficial effects of AdipoRonPEG5 can be partially attributed to improved pharmacokinetics as compared with AdipoRon, thus suggesting that further derivatization may improve affinity and tissue-specific targeting.

ß1 Syntrophin Supports Autophagy Initiation and Protects against Cerulein-Induced Acute Pancreatitis.

Syntrophins are a family of proteins forming membrane-anchored scaffolds and serving as adaptors for various transmembrane and intracellular signaling molecules. To understand the physiological roles of ß1 syntrophin, one of the least characterized members, we generated mouse models to eliminate ß1 syntrophin specifically in the endocrine or exocrine pancreas. ß1 syntrophin is dispensable for the morphology and function of insulin-producing ß cells. However, mice with ß1 syntrophin deletion in exocrine acinar cells exhibit increased severity of cerulein-induced acute pancreatitis. Reduced expression of cystic fibrosis transmembrane conductance regulator and dilation of acinar lumen are potential predisposition factors. During the disease progression, a relative lack of autophagy is associated with deficiencies in both actin assembly and endoplasmic reticulum nucleation. Our findings reveal, for the first time, that ß1 syntrophin is a critical regulator of actin cytoskeleton and autophagy in pancreatic acinar cells and is potently protective against cerulein-induced acute pancreatitis.

Regulation of Dipeptidyl Peptidase-4, its Substrate Chemokines, and Their Receptors in Adipose Tissue of ob/ob Mice.

The physiological function of DPP-4 in proteolytic inactivation of incretins has been well established, however, there is limited information on the expression and the significance of DPP-4 in white adipose tissue with regard to obesity. The objective of the work was to reveal the expression and regulation of DPP-4 in adipocytes and compare the expression and activity of DPP-4 in white adipose tissue and several other organs such as the liver, muscle and kidney. We also investigated the gene expression levels of DPP-4 substrate chemokines, and their receptors in white adipose tissue. DPP-4 was mainly expressed in stromal vascular fraction (SVF), and downregulated in adipose tissue of ob/ob compared with C57BL6/J mice. Mimetic conditions of obese fat in vitro showed that differentiation of mouse primary preadipocytes into adipocytes was associated with marked downregulation of DPP-4 expression. Treatment with TNF-α or ROS even decreased DPP-4 expression in mouse primary adipocytes. Various DPP-4 substrate chemokines were expressed in white adipose tissue and regulated by obesity. The expression of receptors for DPP-4 substrate chemokines was markedly high and tightly regulated by obesity in white adipose tissue. Expression of DPP-4 was reduced in adipose tissues of ob/ob mice. Actions of several substrate chemokines might be potentiated by downregulation of DPP-4, synergistically with upregulation of chemokines and their receptors in adipose tissues of obese mice.

Nur77 gene expression levels were involved in different ACTH-secretion autonomy between Cushing's disease and subclinical Cushing's disease.

Cushing's disease (CD) and subclinical Cushing's disease (subCD) are both diseases caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas. However, ACTH autonomy in subCD is weaker than in CD and there are no Cushingoid features in subCD. The differences of molecular mechanisms in ACTH autonomy between CD and subCD have not yet been reported. Therefore, we aimed to investigate the differences in molecular mechanisms of ACTH-secretion autonomy between CD and subCD. The study included 23 patients [7 CD, 6 subCD, and 10 non-functioning pituitary tumors (NFTs)] who underwent transsphenoidal surgery at the Osaka University Hospital between December 2009 and October 2013. Using quantitative real-time PCR, various ACTH-related gene expressions in tumor tissues from CD, subCD, and NFT were measured such as pro-opiomelanocortin (POMC), POMC transcription factor (Tpit, Pitx1, NeuroD1, and Nur77), POMC peptide processing enzymes (prohormone convertase: PC1/3 and PC2), and ACTH secretion-related factors (corticotropin-releasing hormone receptor 1: CRHR1 and glucocorticoid receptor α: GRα). Only Nur77 mRNA levels were significantly higher in CD than in subCD. Furthermore, we stained 6 CD and 6 subCD with anti-Nur77 antibody. All tumor samples from CD had Nur77 protein positive cells. On the other hand, Nur77 protein was expressed in only one tumor sample from subCD. This sample showed high expression of Nur77 mRNA. Nur77 is an important to regulate POMC transcription and negative-feedback by glucocorticoids. Nur77 gene expression levels might involve different autonomy of ACTH production between CD and subCD.

Clinical significance of fluctuations in thyroid hormones after surgery for Cushing's syndrome.

Patients with Cushing's syndrome (CS) frequently develop hyperthyroidism after surgery due to SITSH (syndrome of inappropriate secretion of TSH) and this SITSH contributed to the symptoms of steroid withdrawal syndrome (SWS). However, the duration of fluctuations in thyroid hormones after surgery for CS remains unknown. The aim of this prospective study was to investigate the clinical course of fluctuation in thyroid hormone level in CS patients after surgery. Thyroid hormone levels [free T3 (FT3), free T4 (FT4) and TSH] and serum cortisol levels were measured before and 1, 3, 6 and 12 months after surgery in 8 patients with active CS (3 pituitary CS and 5 adrenal CS). FT3 levels were above the normal range in 75% of patients up to 6 months after surgery, but returned to the normal range by 12 months. However, TSH levels were not suppressed below the normal range throughout the first 12 months after surgery. Serious symptoms of SWS appeared during the 6-month period after surgery, but disappeared with normalization of thyroid function at 12 months, which was not related to the recovery of function hypothalamus-pituitary-adrenal axis after CS surgery. Therefore, T3 toxicosis could result in deterioration of SWS after surgery for CS. These results indicate that physicians need to take T3 toxicosis into consideration in the pathological evaluation of SWS within 12 months after surgery for CS.

Rapid decline in bone turnover markers but not bone mineral density in acromegalic patients after transsphenoidal surgery.

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play important roles in maintaining bone metabolism and bone mineral density (BMD) in adulthood, in addition to stimulating longitudinal bone growth in childhood. However, information on the effect of GH excess on bone metabolism and BMD is incomplete and requires further analysis. The aim of this study is to clarify the effect of rapid decline in GH levels after transsphenoidal surgery (TSS) on bone metabolism in acromegalic patients. In this prospective study, 22 patients (11 males and 11 females) with active acromegaly underwent TSS. Bone formation marker (serum bone alkaline phosphatase: BAP), bone resorption marker (urinary type I collagen cross-linked N-telopeptide: urinary NTx) and BMD were measured before and at 3 and 12 months after TSS. BAP was significantly decreased at 12 months after TSS, but not at 3 months. Urinary NTx was significantly decreased at 3 and 12 months after TSS. BMD did not change after TSS. In conclusion, the rapid fall in GH level after TSS had no effect on BMD for up to 12 months after TSS despite the decrease in markers of bone formation and resorption.

Downregulation of the kidney glucagon receptor, essential for renal function and systemic homeostasis, contributes to chronic kidney disease.

The glucagon receptor (GCGR) in the kidney is expressed in nephron tubules. In humans and animal models with chronic kidney disease, renal GCGR expression is reduced. However, the role of kidney GCGR in normal renal function and in disease development has not been addressed. Here, we examined its role by analyzing mice with constitutive or conditional kidney-specific loss of the Gcgr. Adult renal Gcgr knockout mice exhibit metabolic dysregulation and a functional impairment of the kidneys. These mice exhibit hyperaminoacidemia associated with reduced kidney glucose output, oxidative stress, enhanced inflammasome activity, and excess lipid accumulation in the kidney. Upon a lipid challenge, they display maladaptive responses with acute hypertriglyceridemia and chronic proinflammatory and profibrotic activation. In aged mice, kidney Gcgr ablation elicits widespread renal deposition of collagen and fibronectin, indicative of fibrosis. Taken together, our findings demonstrate an essential role of the renal GCGR in normal kidney metabolic and homeostatic functions. Importantly, mice deficient for kidney Gcgr recapitulate some of the key pathophysiological features of chronic kidney disease.

Obstructive sleep apnea syndrome causes a pseudo-Cushing's state in Japanese obese patients with type 2 diabetes mellitus.

Activation of the hypothalamic-pituitary-adrenal axis has been reported in some patients with the obstructive sleep apnea syndrome (OSAS). In current study, we investigated whether OSAS affect the screening test for subclinical Cushing's disease using 0.5 mg overnight dexamethasone suppression test (DST) in Japanese obese diabetic patients with OSAS. Among Japanese obese patients with type 2 diabetes mellitus who had been hospitalized in our department, we selected 20 patients with moderate to severe untreated OSAS (apnea-hypoxia index, AHI, of ≥15 events/hour). All patients underwent 0.5 mg DST. The same test was repeated in patients with positive response of it within a few days after continuous positive airway pressure (CPAP) therapy. We found that five patients showed positive response of DST (25%). Three of these patients continued to use CPAP, and they showed normal response of DST after CPAP therapy. Serum cortisol after 0.5 mg DST measured before CPAP therapy correlated significantly with fasting serum cortisol level (r=0.764, p<0.0001), but not with various clinical parameters, including AHI (p=0.784), body mass index (p=0.984), waist circumference (p=0.957), HbA1c (p=0.261), fasting plasma glucose (p=0.420) and HOMA-IR (p=0.500). Our study show that OSAS causes a pseudo-Cushing's syndrome in obese patients with type 2 diabetes mellitus, which phenomena can be reversed by CPAP therapy.

HSP47 levels determine the degree of body adiposity.

Adiposity varies among individuals with the influence of diverse physiological, pathological, environmental, hormonal, and genetic factors, but a unified molecular basis remains elusive. Here, we identify HSP47, a collagen-specific chaperone, as a key determinant of body adiposity. HSP47 expression is abundant in adipose tissue; increased with feeding, overeating, and obesity; decreased with fasting, exercise, calorie restriction, bariatric surgery, and cachexia; and correlated with fat mass, BMI, waist, and hip circumferences. Insulin and glucocorticoids, respectively, up- and down-regulate HSP47 expression. In humans, the increase of HSP47 gene expression by its intron or synonymous variants is associated with higher body adiposity traits. In mice, the adipose-specific knockout or pharmacological inhibition of HSP47 leads to lower body adiposity compared to the control. Mechanistically, HSP47 promotes collagen dynamics in the folding, secretion, and interaction with integrin, which activates FAK signaling and preserves PPARγ protein from proteasomal degradation, partly related to MDM2. The study highlights the significance of HSP47 in determining the amount of body fat individually and under various circumstances.

Protective roles of adiponectin and molecular signatures of HNF4α and PPARα as downstream targets of adiponectin in pancreatic ß cells.

The disease progression of the metabolic syndrome is associated with prolonged hyperlipidemia and insulin resistance, eventually giving rise to impaired insulin secretion, often concomitant with hypoadiponectinemia. As an adipose tissue derived hormone, adiponectin is beneficial for insulin secretion and ß cell health and differentiation. However, the down-stream pathway of adiponectin in the pancreatic islets has not been studied extensively. Here, along with the overall reduction of endocrine pancreatic function in islets from adiponectin KO mice, we examine PPARα and HNF4α as additional down-regulated transcription factors during a prolonged metabolic challenge. To elucidate the function of ß cell-specific PPARα and HNF4α expression, we developed doxycycline inducible pancreatic ß cell-specific PPARα (ß-PPARα) and HNF4α (ß-HNF4α) overexpression mice. ß-PPARα mice exhibited improved protection from lipotoxicity, but elevated ß-oxidative damage in the islets, and also displayed lowered phospholipid levels and impaired glucose-stimulated insulin secretion. ß-HNF4α mice showed a more severe phenotype when compared to ß-PPARα mice, characterized by lower body weight, small islet mass and impaired insulin secretion. RNA-sequencing of the islets of these models highlights overlapping yet unique roles of ß-PPARα and ß-HNF4α. Given that ß-HNF4α potently induces PPARα expression, we define a novel adiponectin-HNF4α-PPARα cascade. We further analyzed downstream genes consistently regulated by this axis. Among them, the islet amyloid polypeptide (IAPP) gene is an important target and accumulates in adiponectin KO mice. We propose a new mechanism of IAPP aggregation in type 2 diabetes through reduced adiponectin action.

Endogenous renal adiponectin drives gluconeogenesis through enhancing pyruvate and fatty acid utilization.

Adiponectin is a secretory protein, primarily produced in adipocytes. However, low but detectable expression of adiponectin can be observed in cell types beyond adipocytes, particularly in kidney tubular cells, but its local renal role is unknown. We assessed the impact of renal adiponectin by utilizing male inducible kidney tubular cell-specific adiponectin overexpression or knockout mice. Kidney-specific adiponectin overexpression induces a doubling of phosphoenolpyruvate carboxylase expression and enhanced pyruvate-mediated glucose production, tricarboxylic acid cycle intermediates and an upregulation of fatty acid oxidation (FAO). Inhibition of FAO reduces the adiponectin-induced enhancement of glucose production, highlighting the role of FAO in the induction of renal gluconeogenesis. In contrast, mice lacking adiponectin in the kidney exhibit enhanced glucose tolerance, lower utilization and greater accumulation of lipid species. Hence, renal adiponectin is an inducer of gluconeogenesis by driving enhanced local FAO and further underlines the important systemic contribution of renal gluconeogenesis.

SARS-CoV-2 infection impairs the insulin/IGF signaling pathway in the lung, liver, adipose tissue, and pancreatic cells via IRF1.

BACKGROUND: COVID-19 can cause multiple organ damages as well as metabolic abnormalities such as hyperglycemia, insulin resistance, and new onset of diabetes. The insulin/IGF signaling pathway plays an important role in regulating energy metabolism and cell survival, but little is known about the impact of SARS-CoV-2 infection. The aim of this work was to investigate whether SARS-CoV-2 infection impairs the insulin/IGF signaling pathway in the host cell/tissue, and if so, the potential mechanism and association with COVID-19 pathology. METHODS: To determine the impact of SARS-CoV-2 on insulin/IGF signaling pathway, we utilized transcriptome datasets of SARS-CoV-2 infected cells and tissues from public repositories for a wide range of high-throughput gene expression data: autopsy lungs from COVID-19 patients compared to the control from non-COVID-19 patients; lungs from a human ACE2 transgenic mouse infected with SARS-CoV-2 compared to the control infected with mock; human pluripotent stem cell (hPSC)-derived liver organoids infected with SARS-CoV-2; adipose tissues from a mouse model of COVID-19 overexpressing human ACE2 via adeno-associated virus serotype 9 (AAV9) compared to the control GFP after SARS-CoV-2 infection; iPS-derived human pancreatic cells infected with SARS-CoV-2 compared to the mock control. Gain and loss of IRF1 function models were established in HEK293T and/or Calu3 cells to evaluate the impact on insulin signaling. To understand the mechanistic regulation and relevance with COVID-19 risk factors, such as older age, male sex, obesity, and diabetes, several transcriptomes of human respiratory, metabolic, and endocrine cells and tissue were analyzed. To estimate the association with COVID-19 severity, whole blood transcriptomes of critical patients with COVID-19 compared to those of hospitalized noncritical patients with COVID-19. RESULTS: We found that SARS-CoV-2 infection impaired insulin/IGF signaling pathway genes, such as IRS, PI3K, AKT, mTOR, and MAPK, in the host lung, liver, adipose tissue, and pancreatic cells. The impairments were attributed to interferon regulatory factor 1 (IRF1), and its gene expression was highly relevant to risk factors for severe COVID-19; increased with aging in the lung, specifically in men; augmented by obese and diabetic conditions in liver, adipose tissue, and pancreatic islets. IRF1 activation was significantly associated with the impaired insulin signaling in human cells. IRF1 intron variant rs17622656-A, which was previously reported to be associated with COVID-19 prevalence, increased the IRF1 gene expression in human tissue and was frequently found in American and European population. Critical patients with COVID-19 exhibited higher IRF1 and lower insulin/IGF signaling pathway genes in the whole blood compared to hospitalized noncritical patients. Hormonal interventions, such as dihydrotestosterone and dexamethasone, ameliorated the pathological traits in SARS-CoV-2 infectable cells and tissues. CONCLUSIONS: The present study provides the first scientific evidence that SARS-CoV-2 infection impairs the insulin/IGF signaling pathway in respiratory, metabolic, and endocrine cells and tissues. This feature likely contributes to COVID-19 severity with cell/tissue damage and metabolic abnormalities, which may be exacerbated in older, male, obese, or diabetic patients.

GPR92 activation in islet macrophages controls ß cell function in a diet-induced obesity model.

The molecular mechanisms underlying obesity-induced increases in ß cell mass and the resulting ß cell dysfunction need to be elucidated further. Our study revealed that GPR92, expressed in islet macrophages, is modulated by dietary interventions in metabolic tissues. Therefore, we aimed to define the role of GPR92 in islet inflammation by using a high-fat diet-induced (HFD-induced) obese mouse model. GPR92-KO mice exhibited glucose intolerance and reduced insulin levels - despite the enlarged pancreatic islets - as well as increased islet macrophage content and inflammation level compared with WT mice. These results indicate that the lack of GPR92 in islet macrophages can cause ß cell dysfunction, leading to disrupted glucose homeostasis. Alternatively, stimulation with the GPR92 agonist farnesyl pyrophosphate results in the inhibition of HFD-induced islet inflammation and increased insulin secretion in WT mice, but not in GPR92-KO mice. Thus, our study suggests that GPR92 can be a potential target to alleviate ß cell dysfunction via the inhibition of islet inflammation associated with the progression of diabetes.

Constitutive expression of IDO by dendritic cells of mesenteric lymph nodes: functional involvement of the CTLA-4/B7 and CCL22/CCR4 interactions.

Dendritic cells (DCs) express the immunoregulatory enzyme IDO in response to certain inflammatory stimuli, but it is unclear whether DCs express this enzyme under steady-state conditions in vivo. In this study, we report that the DCs in mesenteric lymph nodes (MLNs) constitutively express functional IDO, which metabolizes tryptophan to kynurenine. In line with a previous report that regulatory T cells (Tregs) can induce IDO in DCs via the CTLA-4/B7 interaction, a substantial proportion of the MLN DCs were located in juxtaposition to Tregs, whereas this tendency was not observed for splenic DCs, which do not express IDO constitutively. When CTLA-4 was selectively deleted in Tregs, the frequency of IDO-expressing DCs in MLNs decreased significantly, confirming CTLA-4's role in IDO expression by MLN DCs. We also found that the MLN DCs produced CCL22, which can attract Tregs via CCR4, and that the phagocytosis of autologous apoptotic cells induced CCL22 expression in CCL22 mRNA-negative DCs. Mice genetically deficient in the receptor for CCL22, CCR4, showed markedly reduced IDO expression in MLN-DCs, supporting the involvement of the CCL22/CCR4 axis in IDO induction. Together with our previous observation that MLN DCs contain much intracytoplasmic cellular debris in vivo, these results indicate that reciprocal interactions between the DCs and Tregs via both B7/CTLA-4 and CCL22/CCR4 lead to IDO induction in MLN DCs, which may be initiated and/or augmented by the phagocytosis of autologous apoptotic cells by intestinal DCs. Such a mechanism may help induce the specific milieu in MLNs that is required for the induction of oral tolerance.

From friend to foe: Pro-apoptotic action of nuclear ARC in diabetes.

Apoptosis repressor with caspase recruitment domain (ARC) is an established cytoplasmic anti-apoptotic factor relevant for cancer and metabolic disease. In this issue of Developmental Cell, McKimpson et al. show that ARC can assume potent pro-apoptotic effects in ß cells of the endocrine pancreas via translocation to the nucleus.

Adiponectin preserves metabolic fitness during aging.

Adiponectin is essential for the regulation of tissue substrate utilization and systemic insulin sensitivity. Clinical studies have suggested a positive association of circulating adiponectin with healthspan and lifespan. However, the direct effects of adiponectin on promoting healthspan and lifespan remain unexplored. Here, we are using an adiponectin null mouse and a transgenic adiponectin overexpression model. We directly assessed the effects of circulating adiponectin on the aging process and found that adiponectin null mice display exacerbated age-related glucose and lipid metabolism disorders. Moreover, adiponectin null mice have a significantly shortened lifespan on both chow and high-fat diet. In contrast, a transgenic mouse model with elevated circulating adiponectin levels has a dramatically improved systemic insulin sensitivity, reduced age-related tissue inflammation and fibrosis, and a prolonged healthspan and median lifespan. These results support a role of adiponectin as an essential regulator for healthspan and lifespan.

A Novel Model of Diabetic Complications: Adipocyte Mitochondrial Dysfunction Triggers Massive ß-Cell Hyperplasia.

Obesity-associated type 2 diabetes mellitus (T2DM) entails insulin resistance and loss of ß-cell mass. Adipose tissue mitochondrial dysfunction is emerging as a key component in the etiology of T2DM. Identifying approaches to preserve mitochondrial function, adipose tissue integrity, and ß-cell mass during obesity is a major challenge. Mitochondrial ferritin (FtMT) is a mitochondrial matrix protein that chelates iron. We sought to determine whether perturbation of adipocyte mitochondria influences energy metabolism during obesity. We used an adipocyte-specific doxycycline-inducible mouse model of FtMT overexpression (FtMT-Adip mice). During a dietary challenge, FtMT-Adip mice are leaner but exhibit glucose intolerance, low adiponectin levels, increased reactive oxygen species damage, and elevated GDF15 and FGF21 levels, indicating metabolically dysfunctional fat. Paradoxically, despite harboring highly dysfunctional fat, transgenic mice display massive ß-cell hyperplasia, reflecting a beneficial mitochondria-induced fat-to-pancreas interorgan signaling axis. This identifies the unique and critical impact that adipocyte mitochondrial dysfunction has on increasing ß-cell mass during obesity-related insulin resistance.

Lipotoxicity and ß Cell Maintenance in Obesity and Type 2 Diabetes.

Obesity and diabetes are often associated with lipotoxic conditions in multiple tissues. The insulin-producing ß cells are susceptible to elevated lipid levels and the ensuing lipotoxicity. The preservation of ß cell mass and function is one of the main goals of diabetes management under these metabolically stressful conditions. However, the adverse effects from the adaptive signaling pathways that ß cells use to counteract lipotoxic stress have secondary negative effects in their own right. Antilipotoxic signaling cascades in ß cells can contribute to their eventual failure. Such dual roles are seen for many other biological adaptive processes as well.

Adipocyte GR Inhibits Healthy Adipose Expansion Through Multiple Mechanisms in Cushing Syndrome.

In Cushing syndrome, excessive glucocorticoids lead to metabolic disturbances, such as insulin resistance, adipocyte hypertrophy, and liver steatosis. In vitro experiments have highlighted the importance of adipocyte glucocorticoid receptor (GR), but its metabolic roles in vivo have not been fully elucidated in Cushing syndrome. In this study, using clinical samples from patients with Cushing syndrome and adipocyte-specific GR knockout (AGRKO) mice, we investigated the roles of adipocyte GR and its clinical relevance in Cushing syndrome. Under chronic treatment with corticosterone, AGRKO mice underwent healthy adipose expansion with diminished ectopic lipid deposition and improved insulin sensitivity. These changes were associated with Atgl-mediated lipolysis through a novel intronic glucocorticoid-responsive element. Additionally, integrated analysis with RNA sequencing of AGRKO mice and clinical samples revealed that healthy adipose expansion was associated with dysregulation of tissue remodeling, preadipocyte proliferation, and expression of the circadian gene. Thus, our study revealed the roles of adipocyte GR on healthy adipose expansion and its multiple mechanisms in Cushing syndrome.

Dermal adipose tissue has high plasticity and undergoes reversible dedifferentiation in mice.

Dermal adipose tissue (also known as dermal white adipose tissue and herein referred to as dWAT) has been the focus of much discussion in recent years. However, dWAT remains poorly characterized. The fate of the mature dermal adipocytes and the origin of the rapidly reappearing dermal adipocytes at different stages remain unclear. Here, we isolated dermal adipocytes and characterized dermal fat at the cellular and molecular level. Together with dWAT's dynamic responses to external stimuli, we established that dermal adipocytes are a distinct class of white adipocytes with high plasticity. By combining pulse-chase lineage tracing and single-cell RNA sequencing, we observed that mature dermal adipocytes undergo dedifferentiation and redifferentiation under physiological and pathophysiological conditions. Upon various challenges, the dedifferentiated cells proliferate and redifferentiate into adipocytes. In addition, manipulation of dWAT highlighted an important role for mature dermal adipocytes for hair cycling and wound healing. Altogether, these observations unravel a surprising plasticity of dermal adipocytes and provide an explanation for the dynamic changes in dWAT mass that occur under physiological and pathophysiological conditions, and highlight the important contributions of dWAT toward maintaining skin homeostasis.