Human adipose tissue protein analyses using capillary western blot technology

Mineralocorticoid receptor signaling inhibits bladder cancer progression

The biological or clinical significance of mineralocorticoid receptor (MR) in urothelial cancer remains largely unknown. The present study aimed to determine the functional role of MR in bladder cancer progression. In two of the human bladder cancer lines expressing MR, treatment with a natural MR ligand, aldosterone, significantly reduced cell proliferation and migration, which was restored by three MR antagonists clinically used, spironolactone (except colony formation of androgen receptor-positive cells cultured in the presence of androgens), eplerenone, and esaxerenone. Similarly, MR knockdown via shRNA virus infection resulted in significant increases in cell viability/migration, as well as colony formation, compared with control sublines. In addition, MR knockdown augmented the expression of β-catenin, c-fos, and N-cadherin, and lowered that of E-cadherin and p53, indicating the induction of the cadherin switching. Immunohistochemistry in surgical specimens detected MR signals in 58 (92.1%; 36.5% weakly-positive/1+, 44.4% moderately-positive/2+, and 11.1% strongly-positive/3+) of 63 muscle-invasive bladder cancers, which was significantly lower than in adjacent non-neoplastic urothelial tissues (100%; 15.7% 1+, 37.3% 2+, and 47.1% 3+). Moreover, patients with MR-high (3+) tumor had a significantly lower risk of cancer-specific mortality (P=0.039). Multivariable analysis further showed that strong MR expression was an independent predictor of cancer-specific survival in patients with muscle-invasive bladder cancer (hazard ratio 0.117, P=0.039). These findings suggest that MR signaling functions as a tumor suppressor in urothelial carcinoma and prevents tumor growth. Accordingly, there is a possibility that the concurrent use of anti-mineralocorticoids, particularly eplerenone and esaxerenone, in patients with bladder cancer rather contributes to the promotion of disease progression.

Molecular dynamics of genome editing with CRISPR-Cas9 and rAAV6 virus in human HSPCs to treat sickle cell disease

Ex vivo gene correction with CRISPR-Cas9 and a recombinant adeno-associated virus serotype 6 (rAAV6) in autologous hematopoietic stem/progenitor cells (HSPCs) to treat sickle cell disease (SCD) has now entered early-phase clinical investigation. To facilitate the progress of CRISPR-Cas9/rAAV6 genome editing technology, we analyzed the molecular changes in key reagents and cellular responses during and after the genome editing procedure in human HSPCs. We demonstrated the high stability of rAAV6 to serve as the donor DNA template. We assessed the benefit of longer HSPC pre-stimulation in terms of increased numbers of edited cells. We observed that the p53 pathway was transiently activated, peaking at 6 h, and resolved over time. Notably, we revealed a strong correlation between p21 mRNA level and rAAV6 genome number in cells and beneficial effects of transient inhibition of p53 with siRNA on genome editing, cell proliferation, and cell survival. In terms of potential immunogenicity, we found that rAAV6 capsid protein was not detectable, while a trace amount of residual Cas9 protein was still detected at 48 h post-genome editing. We believe this information will provide important insights for future improvements of gene correction protocols in HSPCs.

Ketone Body Infusion Abrogates Growth Hormone-Induced Lipolysis and Insulin Resistance

CONTEXT

Exogenous ketone body administration lowers circulating glucose levels but the underlying mechanisms are uncertain.

OBJECTIVE

We tested the hypothesis that administration of the ketone body β-hydroxybutyrate (βOHB) acutely increases insulin sensitivity via feedback suppression of circulating free fatty acid (FFA) levels.

METHODS

In a randomized, single-blinded crossover design, 8 healthy men were studied twice with a growth hormone (GH) infusion to induce lipolysis in combination with infusion of either βOHB or saline. Each study day comprised a basal period and a hyperinsulinemic-euglycemic clamp combined with a glucose tracer and adipose tissue and skeletal muscle biopsies.

RESULTS

βOHB administration profoundly suppressed FFA levels concomitantly with a significant increase in glucose disposal and energy expenditure. This was accompanied by a many-fold increase in skeletal muscle content of both βOHB and its derivative acetoacetate.

CONCLUSION

Our data unravel an insulin-sensitizing effect of βOHB, which we suggest is mediated by concomitant suppression of lipolysis.

Protective role of mineralocorticoid receptor signaling in urothelial tumorigenesis

The expression status of mineralocorticoid receptor (MR) and its biological significance in human urothelial carcinoma remain unknown. The present study aimed to determine the functional role of MR in the development of urothelial cancer. In human normal urothelial SVHUC cells with exposure to a chemical carcinogen 3-methylcholanthrene (MCA), we assessed the effects of a natural MR ligand, aldosterone, and 3 MR antagonists, including spironolactone, eplerenone, and esaxerenone, as well as knockdown of MR via shRNA virus infection, on their neoplastic/malignant transformation. The in vitro system with carcinogen challenge showed that aldosterone and anti-mineralocorticoids significantly prevented and promoted, respectively, the neoplastic transformation of SVHUC cells. Similarly, MR knockdown in SVHUC cells considerably induced MCA-mediated neoplastic transformation, compared with a control subline. In addition, MR knockdown or antagonist treatment resulted in increases in the expression of β-catenin, c-Fos, and N-cadherin, and a decrease in that of E-cadherin. Meanwhile, spironolactone, which is known to possess anti-androgenic activity, rather suppressed the neoplastic transformation of a SVHUC subline stably expressing wild-type androgen receptor, indicating its dominant effect via the androgen receptor pathway. Immunohistochemistry in surgical specimens detected MR signals in 77 (98.7%; 23.1% weak/1+, 42.3% moderate/2+, and 33.3% strong/3+) of 78 non-invasive bladder tumors, which was significantly (P<0.001) lower than in adjacent non-neoplastic urothelial tissues (100%; 20.5% 2+ and 79.5% 3+). Moreover, the risks for disease recurrence after transurethral surgery were marginally lower in female patients with MR-high (2+/3+) tumor (P=0.068) and significantly lower in all patients with MR-high/glucocorticoid receptor-high tumor (P=0.025), compared with respective controls. These findings suggest that MR signaling functions as a suppressor for urothelial tumorigenesis.

Urinary ATP Levels Are Controlled by Nucleotidases Released from the Urothelium in a Regulated Manner

Adenosine 5′-triphosphate (ATP) is released in the bladder lumen during filling. Urothelial ATP is presumed to regulate bladder excitability. Urinary ATP is suggested as a urinary biomarker of bladder dysfunctions since ATP is increased in the urine of patients with overactive bladder, interstitial cystitis or bladder pain syndrome. Altered urinary ATP might also be associated with voiding dysfunctions linked to disease states associated with metabolic syndrome. Extracellular ATP levels are determined by ATP release and ATP hydrolysis by membrane-bound and soluble nucleotidases (s-NTDs). It is currently unknown whether s-NTDs regulate urinary ATP. Using etheno-ATP substrate and HPLC-FLD detection techniques, we found that s-NTDs are released in the lumen of ex vivo mouse detrusor-free bladders. Capillary immunoelectrophoresis by ProteinSimple Wes determined that intraluminal solutions (ILS) collected at the end of filling contain ENTPD3 > ENPP1 > ENPP3 ≥ ENTPD2 = NT5E = ALPL/TNAP. Activation of adenylyl cyclase with forskolin increased luminal s-NTDs release whereas the AC inhibitor SQ22536 had no effect. In contrast, forskolin reduced and SQ22536 increased s-NTDs release in the lamina propria. Adenosine enhanced s-NTDs release and accelerated ATP hydrolysis in ILS and lamina propria. Therefore, there is a regulated release of s-NTDs in the bladder lumen during filling. Aberrant release or functions of urothelial s-NTDs might cause elevated urinary ATP in conditions with abnormal bladder excitability.

Capillary Western Immunoassay Optimization of Estrogen Related Factors in Human Subcutaneous Adipose Tissue

Lipedema is a multifaceted chronic fat disorder characterized by the bilateral and disproportionate accumulation of fat predominantly in the lower body regions of females. Research strongly supports that estrogen factors likely contribute to the pathophysiology of this disease. We aim to help demonstrate this link by quantifying estrogen factor differences between women with and without lipedema. For time and lipedema adipose tissue conservation, the Protein Simple WES machine will be utilized in place of traditional western blotting. Here, we are interested in evaluating estrogen related factors, such as, but not limited to, estrogen receptors and enzymes involved in the successive conversions of cholesterol and androgens to estrogens in human subcutaneous adipose. Evaluation of these factors within adipose tissue, however, is novel for this instrument. Thus, we optimized tissue lysis and protein extraction for 11 proteins of interest. Antibodies and their working concentrations were determined based upon specific and distinguishable (signal-to-noise) peaks from electropherogram outputs across different tissue lysate concentrations. We found that overnight acetone precipitation proved to be the best procedure for extracting protein from lipid rich adipose tissue samples. Six of the eleven proteins were found to migrate to their expected molecular weights, however, five did not. For proteins that did not migrate as expected, overexpression lysates and empty vector controls were used to validate detection antibodies. Protein extract from subcutaneous adipose tissue and overexpression lysates were then combined to understand if migration was specifically altered by adipose tissue. From these results, we concluded that the lipid rich nature of adipose tissue in combination with the separation matrix designated for use with the WES were preventing the appropriate migration of some proteins rather than non-specific antibody binding or inappropriate preparation methods.

Reversible insulin resistance in muscle and fat unrelated to the metabolic syndrome in patients with acromegaly

BACKGROUND

Patients with active acromegaly exhibit insulin resistance despite a lean phenotype whereas controlled disease improves insulin sensitivity and increases fat mass. The mechanisms underlying this paradox remain elusive, but growth hormone (GH)-induced lipolysis plays a central role. The aim of the study was to investigative the molecular mechanisms of insulin resistance dissociated from obesity in patients with acromegaly.

METHODS

In a prospective study, twenty-one patients with newly diagnosed acromegaly were studied at diagnosis and after disease control obtained by either surgery alone (n=10) or somatostatin analogue (SA) treatment (n=11) with assessment of body composition (DXA scan), whole body and tissue-specific insulin sensitivity and GH and insulin signalling in adipose tissue and skeletal muscle.

FINDINGS

Disease control of acromegaly significantly reduced lean body mass (p<0.001) and increased fat mass (p<0.001). At diagnosis, GH signalling (pSTAT5) was constitutively activated in fat and enhanced expression of GH-regulated genes (CISH and IGF-I) were detected in muscle and fat. Insulin sensitivity in skeletal muscle, liver and adipose tissue increased after disease control regardless of treatment modality. This was associated with enhanced insulin signalling in both muscle and fat including downregulation of phosphatase and tensin homolog (PTEN) together with reduced signalling of GH and lipolytic activators in fat.

INTERPRETATION

In conclusion, the study support that uncontrolled lipolysis is a major feature of insulin resistance in active acromegaly, and is characterized by upregulation of PTEN and suppression of insulin signalling in both muscle and fat.

FUNDING

This work was supported by a grant from the Independent Research Fund, Denmark (7016-00303A) and from the Alfred Benzon Foundation, Denmark.

Influence of Free Fatty Acid Concentrations and Weight Loss on Adipose Tissue Direct Free Fatty Acid Storage Rates

CONTEXT

The factors that determine the recycling of free fatty acids (FFA) back into different adipose tissue depots via the direct storage pathway are not completely understood.

OBJECTIVE

To assess the interactions between adipocyte factors and plasma FFA concentrations that determine regional FFA storage rates.

DESIGN

We measured direct adipose tissue FFA storage rates before and after weight loss under high FFA (intravenous somatostatin and epinephrine) and low (intravenous insulin and glucose) FFA concentrations.

SETTING

Mayo Clinic Clinical Research Unit.

PATIENTS

Sixteen premenopausal women, body mass index 30 to 37 kg/m2.

INTERVENTION

Comprehensive lifestyle weight loss program.

MAIN OUTCOME MEASURE

Direct FFA storage rates in upper and lower body subcutaneous fat.

RESULTS

Over the entire range of FFA and under isolated conditions of elevated FFA concentrations, the storage rates of FFA into upper and lower body subcutaneous fat per unit lipid were associated with concentrations, not adipocyte fatty acid storage factors. Under low FFA conditions, direct FFA storage rates were related to adipocyte CD36 content, not tissue level content of fatty acid storage factors. Weight loss did not change these relationships.

CONCLUSIONS

The regulation of direct FFA storage under low FFA concentration conditions appears to be at the level of the cell/adipocyte content of CD36, whereas under high FFA concentration conditions, direct FFA storage at the tissue level is predicted by plasma FFA concentrations, independent of adipocyte size or fatty acid storage factors. These observations offer novel insights into how adipose tissue regulates direct FFA storage in humans.

Adipocyte Proteins and Storage of Endogenous Fatty Acids in Visceral and Subcutaneous Adipose Tissue in Severe Obesity

OBJECTIVE

This study tested whether substrate concentrations or fatty acid storage proteins predict storage of endogenous lipids in visceral adipose tissue (VAT) and upper body subcutaneous adipose tissue (UBSQ) fat.

METHODS

The day prior to surgery, 25 patients undergoing bariatric procedures received an infusion of autologous [1-¹⁴ C]triolein-labeled very low-density lipoprotein (VLDL) particles, and during surgery, they received a continuous [U-¹³ C]palmitate infusion/bolus [9,10-³ H]palmitate tracer. VAT and UBSQ fat were collected to measure VLDL-triglyceride (TG) storage, direct free fatty acid (FFA) storage rates, CD36 content, lipoprotein lipase (LPL), acyl-CoA synthetase, diacylglycerol acetyl-transferase, and glycerol-3-phosphate acyltransferase activities.

RESULTS

Storage of VLDL-TG and FFA-palmitate in UBSQ and VAT was not different. Plasma palmitate concentrations correlated with palmitate storage rates in UBSQ and VAT (r = 0.46, P = 0.02 and r = 0.46, P = 0.02, respectively). In VAT, VLDL-TG storage was correlated with VLDL concentrations (r = 0.53, P < 0.009) and LPL (r = 0.42, P < 0.05). In UBSQ, VLDL-TG storage was correlated with LPL (r = 0.42, P < 0.05). CD36, acyl-CoA synthetase, glycerol-3-phosphate acyltransferase, and diacylglycerol acetyl-transferase were not correlated with VLDL-TG or palmitate storage.

CONCLUSIONS

Adipose storage of VLDL-TG is predicted by VLDL-TG concentrations and LPL; FFA concentrations predict direct adipose tissue FFA storage rates.

Apolipoprotein M promotes cholesterol uptake and efflux from mouse macrophages

Apolipoprotein M (ApoM) exhibits various anti-atherosclerotic functions as a component of high-density lipoprotein (HDL) particles. Scavenger receptor class B type I (SR-BI) is a classic HDL receptor that mediates selective cholesterol uptake and enhances the efflux of cellular cholesterol to HDL. However, the effect of ApoM on cholesterol transport in macrophages remains unclear. In this study, we identified for the first time that ApoM is expressed in mouse macrophages and is involved in cholesterol uptake, similar to SR-BI. NBD-cholesterol uptake and efflux in cells were characterized using fluorescence spectrophotometry. The uptake ratios of cholesterol by macrophages from ApoM-/- SR-BI-/- mice were significantly lower than those from ApoM+/+ SR-BI-/- and ApoM-/- SR-BI+/+ mice. Real-time fluorescence quantitative PCR was used to analyze the expression of cholesterol transport-related genes involved in cholesterol uptake. ApoM-enriched HDL (ApoM+ HDL) facilitated more cholesterol efflux from murine macrophage Ana-1 cells than ApoM-free HDL (ApoM- HDL). However, recombinant human ApoM protein inhibited the ability of ApoM- HDL to induce cholesterol efflux. In conclusion, ApoM promotes cholesterol uptake and efflux in mouse macrophages. A better understanding of ApoM function may lead to the development of novel therapeutic strategies for treating atherosclerotic diseases.

Insulin-Stimulated Muscle Glucose Uptake and Insulin Signaling in Lean and Obese Humans

PURPOSE

Skeletal muscle is the primary site for insulin-stimulated glucose disposal, and muscle insulin resistance is central to abnormal glucose metabolism in obesity. Whether muscle insulin signaling to the level of Akt/AS160 is intact in insulin-resistant obese humans is controversial.

METHODS

We defined a linear range of insulin-stimulated systemic and leg glucose uptake in 14 obese and 14 nonobese volunteers using a 2-step insulin clamp (Protocol 1) and then examined the obesity-related defects in muscle insulin action in 16 nonobese and 25 obese male and female volunteers matched for fitness using a 1-step, hyperinsulinemic, euglycemic clamp coupled with muscle biopsies (Protocol 2).

RESULTS

Insulin-stimulated glucose disposal (Si) was reduced by > 60% (P < 0.0001) in the obese group in Protocol 2; however, the phosphorylation of Akt and its downstream effector AS160 were not different between nonobese and obese groups. The increase in phosphorylation of Akt2 in response to insulin was positively correlated with Si for both the nonobese (r = 0.53, P = 0.03) and the obese (r = 0.55, P = 0.01) groups. Total muscle GLUT4 protein was 17% less (P < 0.05) in obese subjects.

CONCLUSIONS

We suggest that reduced muscle glucose uptake in obesity is not due to defects in the insulin signaling pathway at the level of Akt/AS160, which suggests there remain significant gaps in our knowledge of muscle insulin resistance in obesity. Our data imply that models of acute lipotoxicity do not replicate the pathophysiology of obesity.

Regulation of direct adipose tissue free fatty acid storage during mixed meal ingestion and high free fatty acid concentration conditions

We found that direct free fatty acid (FFA) storage (fatty acid cycling back into adipose tissue) in leg vs. abdominal subcutaneous fat is related to regional differences in adipose tissue diacylglycerol acyltransferase (DGAT) activity under high-FFA conditions and to differences in adipose tissue acyl-CoA synthetase (ACS)activity under meal ingestion conditions. We also found that direct FFA storage rates in leg fat were significantly less in physically active than sedentary adults. Direct FFA storage into adipocytes relates to body fat distribution. Adipose tissue CD36, ACS, and DGAT may account for some of the between-depot and interindividual variability in FFA storage. These studies were to test whether CD36, ACS, or DGAT might be important for direct palmitate storage under meal ingestion or high-FFA conditions. We measured upper (UBSQ) and lower body subcutaneous (LBSQ) adipose tissue FFA storage rates by infusing palmitate tracers intravenously and performing adipose biopsies under hypoinsulinemic (high-FFA) and mixed-meal conditions. We recruited five postmenopausal women, physically active males (5) and females (5), and sedentary males (5) and females (5). We found that 1) the ratio of UBSQ to LBSQ DGAT activity predicted the ratio of palmitate storage [adjusted R = 0.25, F = 8.0, P = 0.01, 95% CI (0.07, 0.48)] under high-FFA conditions; 2) the ratio of UBSQ to LBSQ ACS activity predicted the ratio of palmitate storage under meal conditions [adjusted R = 0.18, F = 6.3, P = 0.02, 95% CI (0.12, 1.28)]; 3) LBSQ direct palmitate storage rates were significantly less in physically active than sedentary and 4) adipose tissue CD36 protein content, ACS, or DGAT activities did not independently predict palmitate storage rates. We conclude that physically active adults have lesser fatty acid cycling back into adipose tissue and that adipose ACS and DGAT may affect competition between UBSQ and LBSQ adipose for direct palmitate storage.

Temporal patterns of lipolytic regulators in adipose tissue after acute growth hormone exposure in human subjects: A randomized controlled crossover trial

Objective

Growth hormone (GH) stimulates lipolysis, but the underlying mechanisms remain incompletely understood. We examined the effect of GH on the expression of lipolytic regulators in adipose tissue (AT).

Methods

In a randomized, placebo-controlled, cross-over study, nine men were examined after injection of 1) a GH bolus and 2) a GH-receptor antagonist (pegvisomant) followed by four AT biopsies. In a second study, eight men were examined in a 2 × 2 factorial design including GH infusion and 36-h fasting with AT biopsies obtained during a basal period and a hyperinsulinemic-euglycemic clamp. Expression of GH-signaling intermediates and lipolytic regulators were studied by PCR and western blotting. In addition, mechanistic experiments in mouse models and 3T3-L1 adipocytes were performed.

Results

The GH bolus increased circulating free fatty acids (p < 0.0001) together with phosphorylation of signal transducer and activator of transcription 5 (STAT5) (p < 0.0001) and mRNA expression of the STAT5-dependent genes cytokine-inducible SH2-containing protein (CISH) and IGF-1 in AT. This was accompanied by suppressed mRNA expression of G0/G1 switch gene 2 (G0S2) (p = 0.007) and fat specific protein 27 (FSP27) (p = 0.002) and upregulation of phosphatase and tensin homolog (PTEN) mRNA expression (p = 0.03). Suppression of G0S2 was also observed in humans after GH infusion and fasting, as well as in GH transgene mice, and in vitro studies suggested MEK-PPARγ signaling to be involved.

Conclusions

GH-induced lipolysis in human subjects in vivo is linked to downregulation of G0S2 and FSP27 and upregulation of PTEN in AT. Mechanistically, in vitro data suggest that GH acts via MEK to suppress PPARγ-dependent transcription of G0S2. ClinicalTrials.govNCT02782221 and NCT01209429.

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Acute GH exposure in human subjects in vivo stimulates lipolysis and release of FFA together with GH signaling in adipose tissue.

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GH-induced lipolysis is associated with suppression of G0S2 and FSP27 and upregulation of PTEN in human subjects in vivo.

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Inhibition of MEK and activation of PPARγ abrogate GH-induced suppression of G0S2 mRNA expression in vitro.

A Concomitant Muscle Injury Does Not Worsen Traumatic Brain Injury Outcomes in Mice

Traumatic brain injury (TBI) often involves multitrauma in which concurrent extracranial injury occurs. We previously demonstrated that a long bone fracture exacerbates neuroinflammation and functional outcomes in mice given a TBI. Whether other forms of concomitant peripheral trauma that are common in the TBI setting, such as skeletal muscle injury, have similar effects is unknown. As such, here we developed a novel mouse multitrauma model by combining a closed-skull TBI with a cardiotoxin (CTX)-induced muscle injury to investigate whether muscle injury affects TBI outcomes. Adult male mice were assigned to four groups: sham-TBI + sham-muscle injury (SHAM); sham-TBI + CTX-muscle injury (CTX); TBI + sham-muscle injury (TBI); TBI + CTX-muscle injury (MULTI). Some mice were euthanized at 24 h post-injury to assess neuroinflammation and cerebral edema. The remaining mice underwent behavioral testing after a 30-day recovery period, and were euthanized at 35 days post-injury for post-mortem analysis. At 24 h post-injury, both TBI and MULTI mice had elevated edema, increased expression of GFAP (i.e., a marker for reactive astrocytes), and increased mRNA levels of inflammatory chemokines. There was also an effect of injury on cytokine levels at 35 days post-injury. However, the TBI and MULTI mice did not significantly differ on any of the measures assessed. These initial findings suggest that a concomitant muscle injury does not significantly affect preclinical TBI outcomes. Future studies should investigate the combination of different injury models, additional outcomes, and other post-injury time points.