ABSTRACT
Fatty acid synthase (FASN) predominantly generates straight-chain fatty acids using acetyl-CoA as the initiating substrate. However, monomethyl branched-chain fatty acids (mmBCFAs) are also present in mammals but are thought to be primarily diet derived. Here we demonstrate that mmBCFAs are de novo synthesized via mitochondrial BCAA catabolism, exported to the cytosol by adipose-specific expression of carnitine acetyltransferase (CrAT), and elongated by FASN. Brown fat exhibits the highest BCAA catabolic and mmBCFA synthesis fluxes, whereas these lipids are largely absent from liver and brain. mmBCFA synthesis is also sustained in the absence of microbiota. We identify hypoxia as a potent suppressor of BCAA catabolism that decreases mmBCFA synthesis in obese adipose tissue, such that mmBCFAs are significantly decreased in obese animals. These results identify adipose tissue mmBCFA synthesis as a novel link between BCAA metabolism and lipogenesis, highlighting roles for CrAT and FASN promiscuity influencing acyl-chain diversity in the lipidome.
Subject(s)
Adipose Tissue/enzymology , Amino Acids, Branched-Chain/metabolism , Fatty Acid Synthases/metabolism , Fatty Acids/biosynthesis , Obesity/enzymology , 3T3 Cells , Adipocytes/cytology , Animals , CRISPR-Cas Systems , Carnitine O-Acetyltransferase/metabolism , Cytosol/metabolism , Female , Hypoxia , Lentivirus/genetics , Lipogenesis , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Obese , RNA, Small Interfering/metabolismABSTRACT
Adipose tissue plays important roles in regulating carbohydrate and lipid homeostasis, but less is known about the regulation of amino acid metabolism in adipocytes. Here we applied isotope tracing to pre-adipocytes and differentiated adipocytes to quantify the contributions of different substrates to tricarboxylic acid (TCA) metabolism and lipogenesis. In contrast to proliferating cells, which use glucose and glutamine for acetyl-coenzyme A (AcCoA) generation, differentiated adipocytes showed increased branched-chain amino acid (BCAA) catabolic flux such that leucine and isoleucine from medium and/or from protein catabolism accounted for as much as 30% of lipogenic AcCoA pools. Medium cobalamin deficiency caused methylmalonic acid accumulation and odd-chain fatty acid synthesis. Vitamin B12 supplementation reduced these metabolites and altered the balance of substrates entering mitochondria. Finally, inhibition of BCAA catabolism compromised adipogenesis. These results quantitatively highlight the contribution of BCAAs to adipocyte metabolism and suggest that BCAA catabolism has a functional role in adipocyte differentiation.
Subject(s)
Adipocytes/cytology , Adipocytes/metabolism , Amino Acids, Branched-Chain/metabolism , Lipogenesis , Obesity/metabolism , 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)/genetics , 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)/metabolism , 3T3-L1 Cells/drug effects , Acetyl Coenzyme A/metabolism , Adipocytes/drug effects , Adipogenesis/physiology , Adipose Tissue/cytology , Adipose Tissue/metabolism , Animals , Base Sequence , Cell Differentiation/drug effects , Cell Differentiation/physiology , Humans , Mice , Molecular Sequence Data , Obesity/surgery , Tricarboxylic Acids/metabolism , Vitamin B 12/pharmacologyABSTRACT
AIMS/HYPOTHESIS: Tankyrase (TNKS) is a ubiquitously expressed molecular scaffold that is implicated in diverse processes. The catalytic activity of TNKS modifies substrate proteins through poly-ADP-ribosylation (PARsylation) and is responsive to cellular energetic state. Global deficiency of the TNKS protein in mice accelerates glucose utilisation and raises plasma adiponectin levels. The aim of this study was to investigate whether the PARsylation activity of TNKS in adipocytes plays a role in systemic glucose homeostasis. METHODS: To inhibit TNKS-mediated PARsylation, we fed mice with a diet containing the TNKS-specific inhibitor G007-LK. To genetically inactivate TNKS catalysis in adipocytes while preserving its function as a molecular scaffold, we used an adipocyte-selective Cre transgene to delete TNKS exons that encoded the catalytic domain at the C-terminus. Tissue-specific insulin sensitivity in mice was investigated using hyperinsulinaemic-euglycaemic clamps. To model adipose-liver crosstalk ex vivo, we applied adipocyte-conditioned media to hepatocytes and assessed the effect on gluconeogenesis. RESULTS: The TNKS inhibitor G007-LK improved glucose tolerance and insulin sensitivity and promptly increased plasma adiponectin levels. In female mice, but not in male mice, adipocyte-selective genetic inactivation of TNKS catalysis improved hepatic insulin sensitivity and post-transcriptionally increased plasma adiponectin levels. Both pharmacological and genetic TNKS inhibition in female mouse-derived adipocytes induced a change in secreted factors to decrease gluconeogenesis in primary hepatocytes. CONCLUSIONS/INTERPRETATION: Systemic glucose homeostasis is regulated by the PARsylation activity of TNKS in adipocytes. This regulation is mediated in part by adipocyte-secreted factors that modulate hepatic glucose production. Pharmacological TNKS inhibition could potentially be used to improve glucose tolerance.
Subject(s)
Adipose Tissue/drug effects , Adipose Tissue/enzymology , Glucose/metabolism , Tankyrases/metabolism , Animals , Blood Glucose/drug effects , Carbohydrate Metabolism/drug effects , Female , Male , Mice , Sulfones/pharmacology , Tankyrases/antagonists & inhibitors , Triazoles/pharmacologyABSTRACT
Reduced capillary density is a feature of skeletal muscle (SkM) in type 2 diabetes (T2D), which is associated with multiple metabolic and functional abnormalities. SkM has been identified as a secretory tissue, releasing myokines that regulate multiple processes, including vascularization. We sought to determine how myokines secreted from T2D myotubes might influence SkM angiogenesis. Conditioned media (CM) were generated by myotubes from T2D and nondiabetic (ND) subjects. Primary human endothelial cells (HUVEC) and SkM explants were exposed to CM or recombinant myokines, and tube number or capillary outgrowth was determined as well as measurement of protein expression and phosphorylation. CM from ND myotubes stimulated tube formation of HUVEC to a greater extent than T2D myotubes (T2D-CM = 100%, ND-CM = 288 ± 90% after 48 h, P < 0.05). The effects of T2D myotube CM were mediated by IL-8, not IL-15 or GROα, and were due not to cell damage but rather through regulating tube production and maintenance (response to T2D-IL-8 = 100%, response to ND-IL-8 = 263 ± 46% after 48 h, P < 0.05). A similar effect was seen in SkM explants with exposure to IL-8. The dose-dependent effect of IL-8 on tube formation was also observable in the PI3K and FAK signaling pathways and mediated at least in part by PI3K, leading to regulation of Tie2 expression. These results suggest that elevated levels of IL-8 secreted from T2D myotubes create a muscle microenvironment that supports reduced capillarization in T2D. Impaired vascularization of SkM limits the availability of substrates, including glucose and contributes to the T2D phenotype.
Subject(s)
Diabetes Mellitus, Type 2/metabolism , Interleukin-8/metabolism , Muscle Fibers, Skeletal/physiology , Muscle, Skeletal/metabolism , Phosphatidylinositol 3-Kinases/physiology , Receptor, TIE-2/physiology , Case-Control Studies , Cell Proliferation , Cells, Cultured , Diabetes Mellitus, Type 2/pathology , Female , Human Umbilical Vein Endothelial Cells , Humans , Interleukin-8/blood , Male , Middle Aged , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/pathology , Signal Transduction/physiologyABSTRACT
Summary: A 6.6-year-old female presented to endocrinology with precocious puberty for evaluation and management. Workup was initiated, and a diagnosis of central precocious puberty was confirmed. A decision was made to initiate pubertal blockade using gonadotropin-releasing hormone agonist (GnRHa) therapy with depot leuprolide acetate injections every 3 months. The patient received the first depot leuprolide acetate injection in the right ventrogluteal area. Six hours following the injection, the patient was reported to be inconsolable in pain, which was localized to the right hip site of the earlier injection and associated with a refusal to ambulate. The pain and discomfort continued to progress over the next 24 h despite an alternating regimen of Tylenol and ibuprofen prompting admission to the emergency department. Vital signs demonstrated a low-grade fever and elevated C-reactive protein. An ultrasound of the right hip demonstrated fluid accumulation within the joint. Over the next week, the patient was unable to walk independently and required assistance for activities of daily living. By 2 weeks after the injection, the pain began to remit, and the patient resumed activities of daily living. Following consultation with allergy, a decision was made to continue GnRHa suppressive therapy with an alternative analog (Triptodur). The patient tolerated subsequent treatment without reaction. Learning points: Although gonadotropin-releasing hormone agonists (GnRHa) have a generally good safety profile, there is a history of both local and systemic hypersensitivity reactions associated with their use. Despite the long-acting formulation of depot leuprolide acetate, the systemic reaction in this case appears to be self-limited. Discontinuation of therapy or a change to an alternative formulation of GnRHa analog should be considered based on the need for therapy versus the potential risk of rechallenge.
ABSTRACT
Summary: An 11-year-old girl with past medical history of septic shock and multi-organ failure at age 5 presented to her primary care doctor with concern for pallor of the lips. Laboratory studies demonstrated low free thyroxine (T4) and normal thyroid-stimulating hormone (TSH). A referral to endocrinology was made where the patient was evaluated, and laboratory evaluation was repeated. The patient was asymptomatic and clinically euthyroid with a height consistent with her mid-parental height and was in mid- to late-puberty. The repeated laboratory evaluation demonstrated a pattern suggestive of primary hypothyroidism with low free T4 and an elevated TSH. However, the magnitude of elevation of TSH was less than expected, given the degree of lowering of free T4; therefore, central hypothyroidism was considered. Workup was initiated, and laboratory studies and MRI imaging confirmed an underlying diagnosis of panhypopituitarism in the setting of pituitary stalk interruption syndrome. Learning points: Pituitary stalk interruption syndrome is a rare but important cause of panhypopituitarism. Central hypothyroidism should be suspected in patients with low free thyroxine with an inappropriate degree of elevation of thyroid-stimulating hormone. Workup of central hypothyroidism should include multi-pituitary hormone assessment, and, if evident, MRI imaging should be done. Adrenal insufficiency should be suspected in a hypotensive, critically ill patient who is failing to improve on standard-of-care therapy.
ABSTRACT
OBJECTIVE: To determine the effects of cysteamine on adiponectin multimerization in sera of patients with nonalcoholic fatty liver disease (NAFLD). STUDY DESIGN: Sera from 10 children with biopsy-proven NAFLD treated with cysteamine were assayed for adiponectin multimers at baseline, after 24 weeks of treatment, and again 16 weeks after discontinuing treatment. Pretreatment sera from subjects with NAFLD and from adult controls without NAFLD controls (n = 8) were incubated in cysteamine and multimers were measured 1 hour later. A cysteamine/adiponectin multimer dose-response curve was created. RESULTS: Following 24 weeks of cysteamine therapy, the mean percentage increase for high, medium (MMW), and low (LMW) molecular weight multimers and total adiponectin from baseline was 53% (P = .02), 19% (P = .02), 29.4% (P = .03), and 49.3% (P = .05), respectively. Levels returned to baseline at 16 weeks after stopping therapy, unlike hepatic transaminase levels which remained low. Sera from 0 week, incubated in cysteamine for 1 hour, showed a significant mean percent increase in LMW adiponectin levels and a mean percent reduction in MMW levels compared with baseline in adults with and without NAFLD. CONCLUSIONS: Cysteamine impacts adiponectin multimerization. Long-term cysteamine therapy increases levels of all multimers, whereas, in vitro short-term exposure causes a rapid increase in LMW and reduction in MMW multimers in NAFLD and healthy controls. Cysteamine may be a potential therapeutic agent for conditions associated with insulin-resistance, oxidative stress, and depressed adiponectin levels.
Subject(s)
Adiponectin/chemistry , Cysteamine/pharmacology , Protein Multimerization/drug effects , Adiponectin/blood , Antioxidants/pharmacology , Antioxidants/therapeutic use , Child , Cysteamine/therapeutic use , Dose-Response Relationship, Drug , Electrophoresis, Gel, Two-Dimensional , Fatty Liver , Humans , Non-alcoholic Fatty Liver DiseaseABSTRACT
BACKGROUND: Elevated stearoyl-CoA desaturase activity has been described in obese states, with an increased desaturation index (DI) suggesting enhanced lipogenesis. Differences in the DI among various phenotypes of abnormal adiposity have not been studied. Abnormal accumulation of subcutaneous adipose tissue occurs in rare adipose disorders (RADs) including Dercum's disease (DD), multiple symmetric lipomatosis (MSL), and familial multiple lipomatosis (FML). Examining the DI in subcutaneous fat of people with DD, MSL and FML may provide information on adipose tissue fatty acid metabolism in these disorders. The aims of this pilot study were: 1) to determine if differences in adipose tissue DIs are present among RADs, and 2) to determine if the DIs correlate to clinical or biochemical parameters. METHODS: Subcutaneous adipose tissue was obtained from human participants with DD (n = 6), MSL (n = 5), FML (n = 8) and obese Controls (n = 6). Fatty acid composition was determined by gas chromatography/mass spectrometry. The DIs (palmitoleic/palmitic, oleic/stearic, vaccenic/stearic ratios) were calculated from the gas chromatogram peak intensities. SCD1 gene expression was determined. Spearman's correlations between the DIs and available clinical or biochemical data were performed. RESULTS: In DD subjects, the vaccenic/stearic index was lower (p < 0.05) in comparison to Controls. Percent of total of the saturated fatty acid myristic acid was higher in DD compared with Controls and FML. Percent of monounsaturated vaccenic acid in DD trended lower when compared with Controls, and was decreased in comparison to FML. In MSL, total percent of the polyunsaturated fatty acids was significantly lower than in the Control group (p < 0.05). In the total cohort of subjects, the palmitoleic/palmitic and oleic/stearic DIs positively correlated with age, BMI, and percent body fat. CONCLUSIONS: The positive associations between the DIs and measures of adiposity (BMI and percent body fat) support increased desaturase activity in obesity. The lower vaccenic/stearic DI in DD SAT compared with Controls suggests presence of other factors involved in fat accumulation in addition to lifestyle. Other mechanisms driving fat accumulation in DD such as inflammation or lymphatic dysfunction should be investigated.
Subject(s)
Fatty Acids/metabolism , Lipomatosis/metabolism , Subcutaneous Fat/metabolism , Adult , Body Mass Index , Case-Control Studies , Female , Gene Expression , Humans , Lipogenesis , Male , Middle Aged , Obesity/metabolism , Stearoyl-CoA Desaturase/genetics , Stearoyl-CoA Desaturase/metabolismABSTRACT
BACKGROUND: Activated phosphoinositide 3-kinase (PI3K) δ syndrome (APDS) is a rare form of primary immunodeficiency with 243 known cases reported in the literature. Known findings associated with the condition include recurrent sinusitis and bronchitis, bronchiectasis, immune cytopenias, mild developmental delay, splenomegaly, and lymphadenopathy. We report the case of a child with APDS accompanied by unique clinical features: nephromegaly and growth hormone deficiency with associated pituitary anatomic abnormality. CASE PRESENTATION: The patient is a nine-year-old boy with a heterozygous de novo variant in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit δ (p.E1021K), previously reported in association with APDS. Our patient, who had no family history of immunodeficiency, exhibits classic findings of this syndrome but also has unique features that extend the phenotypic spectrum of this disorder. At 5 years of age, the patient showed marked growth deceleration and was demonstrated to have growth hormone (GH) deficiency with associated pituitary anatomic abnormality. He started GH therapy with an excellent response. He additionally has bilateral nephromegaly of unclear etiology, microscopic hematuria and proteinuria, asthma, and has developed left hip pain with arthrocentesis consistent with oligoarticular juvenile idiopathic arthritis. At age nine, the patient was referred to genetics and whole exome sequencing revealed APDS. Though there was initial concern that GH may increase risk for malignancy as GH signals through the PI3K pathway, he was allowed to continue treatment as the PI3K pathway was considered constitutively active at baseline. CONCLUSIONS: Our patient's unique presentation adds to the clinical information regarding APDS, demonstrates the utility of genetic testing and illustrates the importance of a multidisciplinary collaborative approach in managing this complex syndrome.
ABSTRACT
OBJECTIVES: The Bethesda system for reporting cytopathology (TBSRTC) has been widely adopted in the management of thyroid nodules. Based on the limited pediatric data available, the implied malignancy risk for each of the categories may be significantly different in pediatrics vs. adults, especially in the indeterminate categories (Bethesda Class III or IV). We report the diagnostic utility of fine needle aspiration (FNA) biopsy at our institution based on the Bethesda system and the risk of malignancy in each category. METHODS: We retrospectively reviewed all patients who underwent a thyroid FNA at our tertiary pediatric hospital from 12/1/2002 to 11/30/2018. FNA results were classified according to TBSRTC. Patient demographics, cytology, histopathology, radiological and clinical follow-ups were examined. RESULTS: A total of 171 patients were included with 203 cytological samples. Average age at initial FNA was 14.7 years (range 6.9-18.6 years). The numbers of nodules reported for Bethesda categories I-VI were 29, 106, 22, 14, 6 and 26, respectively, and the rate of malignancy was: 13.8, 4.7, 22.7, 35.7, 83.3 and 100%, respectively. Use of ultrasound guidance reduced the non-diagnostic rate from 38.1 to 11.5%. Introduction of on-site adequacy testing further reduced the non-diagnostic rate to 6.5% since 2014. CONCLUSIONS: The risk of malignancy for thyroid nodules in this pediatric cohort is higher than reported in adults. However, rates described here are much closer to adult ranges than previously published pediatric cohorts. The addition of adequacy testing improved the non-diagnostic rate of FNA procedures performed with ultrasound guidance.
Subject(s)
Biopsy, Fine-Needle/methods , Thyroid Nodule/diagnosis , Thyroid Nodule/pathology , Adolescent , Child , Cytodiagnosis/methods , Female , Humans , Male , Reproducibility of Results , Retrospective Studies , Thyroid Neoplasms/classification , Thyroid Neoplasms/diagnosis , Thyroid Neoplasms/pathology , Thyroid Nodule/classification , Ultrasonography, InterventionalABSTRACT
Adiponectin, an insulin-sensitizing factor secreted from adipose tissue, is decreased in individuals with type 2 diabetes (T2D) and increased in response to thiazolidinedione (TZD) therapy. Changes in its secretion and assembly into higher-order forms affect insulin sensitivity. To determine the relative potency of TZDs on intra-adipocyte multimerization and secretion of adiponectin, we assessed the impact of in vivo low- or high-dose rosiglitazone treatment alone or combined with metformin in subjects with T2D. T2D subjects received high-dose rosiglitazone (8 mg/day), high-dose metformin (2,000 mg/day), or low-dose combination rosiglitazone-metformin therapy (4 mg + 1,000 mg/day) for 4 mo. All subjects were then switched to high-dose rosiglitazone-metformin combination therapy (8 mg + 2,000 mg/day) for another 4 mo. Low-dose rosiglitazone increased serum adiponectin, whereas the high dose increased both adipocyte content and serum adiponectin levels. TZDs selectively increased the percentage of circulating adiponectin in the potent, high-molecular-weight (HMW) form. No TZD effects were evident on multimer distribution in the cell. Expression of the chaperone protein ERp44, which retains adiponectin within the cell, was decreased by TZD treatment. No changes occurred in Ero1-Lalpha expression. Metformin had no effect on any of these measures. Increases in adiponectin correlated with improvements in insulin sensitivity. In vivo, TZDs have apparent dose-dependent effects on cellular and secreted adiponectin. TZD-mediated improvements in whole body insulin sensitivity are associated with increases in circulating but not cellular levels of the HMW adiponectin multimer. Finally, TZDs promote the selective secretion of HMW adiponectin, potentially, in part, through decreasing the expression of the adiponectin-retaining protein ERp44.
Subject(s)
Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/metabolism , Hypoglycemic Agents/pharmacology , Intracellular Space/metabolism , Protein Multimerization/drug effects , Adiponectin/blood , Adiponectin/chemistry , Adiponectin/metabolism , Adult , Aged , Diabetes Mellitus, Type 2/blood , Dose-Response Relationship, Drug , Double-Blind Method , Female , Humans , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/therapeutic use , Intracellular Space/drug effects , Male , Metformin/administration & dosage , Middle Aged , Molecular Weight , Protein Isoforms/blood , Protein Isoforms/chemistry , Protein Isoforms/metabolism , Rosiglitazone , Substrate Specificity , Thiazolidinediones/administration & dosage , Thiazolidinediones/pharmacology , Thiazolidinediones/therapeutic use , Young AdultABSTRACT
BACKGROUND: Adiponectin is an adipokine with anti-atherogenic and insulin-sensitizing properties. Specific adiponectin receptors, adiponectin receptors 1 (AdipoR1) and 2 (AdipoR2), are present in adipose tissue, indicating adiponectin might have autocrine/paracrine effects on its production or action. In addition, endoplasmic reticulum oxidoreductase 1-Lalpha might mediate regulation of its secretion. The study aim was to determine the subcutaneous adipose tissue (SAT) adiponectin gene and protein expression and their correlation to metabolic parameters during metabolically distinct times after gastric bypass surgery. METHODS: A total of 12 morbidly obese male patients underwent SAT biopsy during gastric bypass surgery, active weight loss (negative energy state), and at weight stabilization (steady state energy). The SAT mRNA and protein content of adiponectin, AdipoR1 and AdipoR2, and endoplasmic reticulum oxidoreductase 1-Lalpha protein levels and the serum levels of adiponectin were assessed. RESULTS: SAT adiponectin, AdipoR1, and AdipoR2 gene expression increased significantly at the negative energy state, with no further change at steady state energy (P<.05, P<.05, and P=.04, respectively), without significant increases in protein at any stage. Changes in SAT adiponectin protein correlated with changes in AdipoR1 and AdipoR2 during steady state energy (P=.003 and P=.002, respectively). Changes in SAT adiponectin expression did not correlate with those in circulating levels. Changes in endoplasmic reticulum oxidoreductase 1-Lalpha did not correlate with either SAT or circulating levels of adiponectin. CONCLUSION: Our data indicate distinct functions of adiponectin receptors, AdipoR1 and AdipoR2, mediate the autocrine/paracrine actions of adiponectin. The lack of correlation between changes in SAT adiponectin gene and protein expression and its circulating levels suggests that adipose tissue synthesis and release of adiponectin are highly regulated pathways.
Subject(s)
Adiponectin/genetics , DNA/genetics , Gene Expression Regulation , Obesity, Morbid/genetics , Receptors, Adiponectin/genetics , Subcutaneous Fat/metabolism , Adiponectin/blood , Adult , Autoradiography , Biomarkers/metabolism , Biopsy , Blotting, Western , Energy Metabolism/genetics , Follow-Up Studies , Gastric Bypass , Genetic Predisposition to Disease , Humans , Laparoscopy , Male , Membrane Glycoproteins/biosynthesis , Membrane Glycoproteins/genetics , Middle Aged , Obesity, Morbid/metabolism , Obesity, Morbid/surgery , Oxidoreductases Acting on Sulfur Group Donors/biosynthesis , Oxidoreductases Acting on Sulfur Group Donors/genetics , Polymerase Chain Reaction , Postoperative Period , Prognosis , Receptors, Adiponectin/biosynthesis , Subcutaneous Fat/pathologyABSTRACT
Girls with either hypo- or hypergonadotropic hypogonadism need treatment with estrogens to initiate puberty and maintain a normal hormonal milieu. The focus of this review is hormone replacement treatment in girls with hypogonadism, to initiate and progress through puberty, and to maintain a healthy hormonal milieu in women. It also addresses what is known in the literature regarding estrogen levels in girls and women, instructive cases, practical tables for reference and application, and thoughts on future directions in this area. It represents a thorough literature review with author opinions and recommendations. Girls with normal ovarian function begin puberty on average at 10.5 years old, although there is variation according to ethnicity and degree of excess weight gain. The aim of estrogen therapy to initiate puberty is to mimic normal onset and rate of progression. On the basis of the currently available literature, when a diagnosis of hypogonadism is established, we recommend initiating treatment between age 11 and 12 years of age, with dose increases approximately every 6 months until adult levels are reached. In some situations, treatment may be delayed to allow time for diagnosis or permit more time for linear growth, or address unique risks found in girls treated for various cancers or blood disorders. When adult dosing is reached, progestins are also used to protect uterine health. This can be combined sequentially, allowing regular menstruation, or combined continuously when menstrual bleeding is not preferred. Treatment is continued until the average age of menopause, again with various considerations for longer or shorter duration on the basis of risk-benefit ratios. Transdermal estrogens are considered the most physiologic replacement and theoretically might have fewer associated risks. We review what is known about risks and outcomes and areas for future research.
Subject(s)
Estrogen Replacement Therapy/methods , Estrogens/therapeutic use , Hypogonadism/drug therapy , Adolescent , Child , Estrogens/pharmacology , Female , Humans , Sexual Maturation/drug effectsABSTRACT
We recently reported that stressed adipocytes release extracellular vesicles (EVs) that act as "find-me" signals to promote macrophage migration and activation. In this study, we performed a comprehensive characterization of stressed adipocyte-derived EVs, assessing their antigenic composition, lipidomics, and RNA profiles. Perilipin A was identified as one of the adipose-specific proteins and studied as a potential novel biomarker to detect adipocyte-derived EVs in circulation. Circulating EVs were significantly increased in mice with diet-induced obesity (DIO) and in obese humans with metabolic syndrome compared to lean controls. This increase was associated with decreased glucose tolerance in the DIO mice and metabolic dysfunction, elevated insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) in the obese humans. EVs from both DIO mice and obese humans were enriched in perilipin A, a central gatekeeper of the adipocyte lipid storehouse and a marker of adipocyte differentiation. In obese humans, circulating levels of EVs enriched in perilipin A were dynamic, decreasing 35 % (p < 0.05) after a 3-month reduced calorie diet intervention. This translational study provides an extensive characterization of adipocyte-derived EVs. The findings identify perilipin A as a novel biomarker of circulating EVs of adipocyte origin and support the development of circulating perilipin A-positive EVs as indicators of adipose tissue health. KEY MESSAGE: ⢠Extensive characterization of 3T3L1 EVs identified perilipin A in their composition. ⢠Circulating EVs are elevated in obese mice and associated with glucose intolerance. ⢠Circulating EVs are elevated in obese human and correlated with metabolic factors. ⢠Perilipin A and EV levels are increased in the circulation of obese mice and human. ⢠Circulating EV and perilipin A levels decrease with low calorie intervention.
Subject(s)
Adipocytes/metabolism , Extracellular Vesicles/metabolism , Stress, Physiological , 3T3-L1 Cells , Adipocytes/drug effects , Adult , Animals , Biomarkers/metabolism , Caloric Restriction , Cells, Cultured , Extracellular Vesicles/drug effects , Humans , Insulin/blood , Insulin/pharmacology , Insulin Resistance , Lipids/analysis , Metabolomics , Mice , Mice, Inbred C57BL , MicroRNAs/metabolism , Obesity/blood , Obesity/metabolism , Obesity/pathology , Perilipin-1/metabolism , Proteins/metabolism , Proteomics , Sequence Analysis, RNA , Stress, Physiological/drug effectsABSTRACT
BACKGROUND: Well-differentiated thyroid cancer (WDTC) incidence in pediatrics is rising, most being papillary thyroid carcinoma (PTC). The objective of the study was to assess the prevalence of different mutations in pediatric WDTC and correlate the genotype with the clinical phenotype. METHODS: This is a single-center retrospective study. Thyroid tissue blocks from 42 consecutive pediatric WDTC patients who underwent thyroidectomy between 2001 and 2013 were analyzed at Quest Diagnostics for BRAF(V600E), RAS mutations (N,K,H), and RET/PTC and PAX8/PPARγ rearrangements, using validated molecular methods. Thyroid carcinomas included PTC, follicular thyroid carcinoma (FTC), and follicular variant of PTC (FVPTC). RESULTS: Thirty-nine samples (29 females) were genotyped. The mean age at diagnosis was 14.7 years (range 7.9-18.4 years), and most were Hispanic (56.4%) or Caucasian (35.9%). The mean follow-up period was 2.9 years. Mutations were noted in 21/39 (53.8%), with both BRAF(V600E) (n = 9), and RET/PTC (n = 6) detected only in PTC. Mutations were detected in 2/5 FTC (PAX8/PPARγ and NRAS) and 3/6 FVPTC cases (PAX8/PPARγ). Of 28 PTC patients, 57.1% had mutations: 32.1% with BRAF(V600E), 21.4% with RET/PTC, and 3.6% with NRAS. Of patients with BRAF(V600E), 77.8% were Hispanic and 88.9% were >15 years, while all RET/PTC-positive patients were ≤15 years (p = 0.003). Tumor size, lymph node involvement, and distant metastasis at diagnosis (or soon after (131)I ablation) did not vary significantly based on the mutation. CONCLUSIONS: BRAF(V600E) was the most common mutation, especially in older and Hispanic adolescents. A larger, ethnically diverse pediatric cohort followed long term will enable the genotypic variability, clinical presentation, and response to therapy to be better assessed.
Subject(s)
Adenocarcinoma, Follicular/genetics , Carcinoma, Papillary, Follicular/genetics , DNA Mutational Analysis , Thyroid Neoplasms/genetics , Adenocarcinoma, Follicular/ethnology , Adolescent , Age Factors , Carcinoma, Papillary, Follicular/ethnology , Cell Differentiation , Child , Ethnicity , Female , Follow-Up Studies , Genetic Association Studies , Genetic Predisposition to Disease , Humans , Male , Phenotype , Retrospective Studies , Thyroid Neoplasms/ethnology , Young AdultABSTRACT
CONTEXT: The insulin analog LysB3,GluB29-insulin (glulisine) displays accelerated in vivo bioavailability compared with native insulin. OBJECTIVE: Biological properties of this rapid-acting insulin analog were compared with the actions of native insulin and IGF-I. DESIGN: The effects of the hormones on hormone binding, glucose uptake, and thymidine uptake were evaluated in cultured human skeletal muscle cells. SETTING: This study was performed at a Veterans Administration hospital for patient characterization and tissue biopsies; in vitro studies were performed in a research laboratory. PATIENTS OR OTHER PARTICIPANTS: Skeletal muscle tissue was obtained from nondiabetic (n = 13) and type 2 diabetic (n = 14) subjects. INTERVENTION: Cultured skeletal muscle cells were treated acutely (15-90 min) or chronically (16 h) with varying concentrations of hormones. MAIN OUTCOME: The main study outcomes were measures of sensitivity (concentration required to attain 50% displacement of specific [125I]insulin or [125I]IGF-I bound and sensitivity (EC50) and potency (maximal response) for hormone binding and biological responses. RESULTS: Insulin and glulisine were comparable in their ability to displace insulin binding. Neither insulin nor glulisine competed efficiently for IGF-I binding. Insulin, glulisine, and IGF-I were equipotent in the stimulation of glucose uptake. Maximal stimulation of phosphorylation of Akt was greatest for IGF-I, whereas sensitivities were similar to those for glucose uptake. Sensitivities were comparable in muscle cells from nondiabetic and type 2 diabetic subjects. Stimulation of [3H]thymidine uptake was most responsive to IGF-I; insulin and glulisine were equally less effective, with sensitivities approximately 1-2% of that for IGF-I. Stimulation of p42/44 MAPK phosphorylation reflected the behavior of thymidine uptake. CONCLUSIONS: Although altered pharmacokinetics of glulisine can have therapeutic advantages, glulisine is indistinguishable from native insulin at the skeletal muscle level.
Subject(s)
Hypoglycemic Agents/pharmacology , Insulin-Like Growth Factor I/pharmacology , Insulin/analogs & derivatives , Muscle, Skeletal/drug effects , Adult , Cells, Cultured , DNA/biosynthesis , Diabetes Mellitus, Type 2/metabolism , Diabetes Mellitus, Type 2/pathology , Female , Glucose/metabolism , Humans , Insulin/metabolism , Insulin/pharmacology , Insulin Resistance/physiology , Insulin-Like Growth Factor I/metabolism , Male , Middle Aged , Mitogen-Activated Protein Kinases/metabolism , Mitosis/drug effects , Muscle, Skeletal/metabolism , Phosphorylation , Signal Transduction/drug effects , Thymidine/metabolismABSTRACT
The relationship between insulin action and control of the adipocyte-derived factor adiponectin was studied in age- and weight-matched obese individuals with type 2 diabetes failing sulfonylurea therapy. After initial metabolic characterization, subjects were randomized to troglitazone or metformin treatment groups; all subjects received glyburide (10 mg BID) as well. Treatment was continued for 3 months. The extent of glycemic control after treatment was similar in both groups. However, the increase in maximal insulin-stimulated glucose disposal rate was greater following troglitazone therapy (+44%) compared with metformin treatment (+20%). Troglitazone treatment increased serum adiponectin levels nearly threefold. There was no change in serum adiponectin with metformin treatment. A positive correlation was found between increases in whole-body glucose disposal rates and serum adiponectin levels after troglitazone; no such relationship was seen with metformin. The adiponectin protein content of subcutaneous abdominal adipocytes was increased following troglitazone treatment and unchanged after metformin. Adiponectin release from adipocytes was also augmented with troglitazone treatment. Adiponectin was present in adipocytes and plasma in several multimeric forms; a trimer was the major form secreted from adipocytes. These results indicate that increases in adiponectin content and secretion are associated with improved insulin action but are not directly related to glycemic control. Modulation of adipocyte function, including upregulation of adiponectin synthesis and secretion, may be an important mechanism by which thiazolidinediones influence insulin action.
Subject(s)
Adipose Tissue/metabolism , Diabetes Mellitus, Type 2/drug therapy , Hypoglycemic Agents/therapeutic use , Intercellular Signaling Peptides and Proteins , Proteins/metabolism , Thiazolidinediones , Adipocytes/chemistry , Adiponectin , Adult , Aged , Biopsy , Chromans/therapeutic use , Culture Media, Conditioned , Diabetes Mellitus/blood , Diabetes Mellitus/drug therapy , Diabetes Mellitus/metabolism , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/metabolism , Female , Glyburide/therapeutic use , Humans , Male , Metformin/therapeutic use , Middle Aged , Molecular Weight , Obesity/blood , Obesity/metabolism , Proteins/analysis , Proteins/chemistry , Thiazoles/therapeutic use , Tissue Distribution , TroglitazoneABSTRACT
Adiponectin is an insulin sensitizing fat cell (FC) hormone whose levels are related to adipose tissue (AT) mass and depot distribution. We hypothesized that the nature of AT expansion (hypertrophy vs. hyperplasia) contributes to obesity-related reductions in serum adiponectin and that this effect is influenced by the regional distribution of AT to subcutaneous (S) and visceral (V) depots. Thirteen obese subjects provided paired AT biopsies. Serum total and high molecular weight (HMW) adiponectin levels were determined by ELISA. Secretion was quantified following 24-h explant culture. FC size, number, % large, and % small FC were determined by microscopic analysis. Secretion of total adiponectin was highest by SAT (P = 0.008) and correlated more strongly with serum adiponectin (total: P = 0.015, r = 0.77; HMW: P = 0.005, r = 0.83) than did secretion by VAT (P = 0.05, r = 0.66 for both). FC size was greatest in SAT and correlated negatively with both serum (total: P = 0.01, r = -0.74; HMW: P = 0.03, r = -0.69) and secreted (total: P = 0.05, r = -0.72; HMW: P = 0.02, r = -0.87) adiponectin. The % small FC in SAT correlated positively with both serum (total: P = 0.006, r = 0.87; HMW: P = 0.009, r = 0.79) and secreted (total: P = 0.03, r = 0.75; HMW: P = 0.01, r = 0.92) adiponectin. VAT FC size correlated negatively with serum HMW adiponectin (P = 0.01, r = -0.76) but not with any measure of secretion. VAT had the greatest % small FC, which related positively to serum HMW (P = 0.004, r = 0.81) and to secreted total adiponectin (P = 0.02, r = 0.78). These studies indicate that differences in fat cell size and depot distribution of AT expansion are important influences on adiponectin in obesity.
ABSTRACT
Adiponectin is an insulin-sensitizing and anti-inflammatory fat cell hormone that has immense potential as a therapeutic target for a multitude of obesity-associated diseases, including type 2 diabetes, NASH and atherosclerosis (Chandran M, Phillips SA, Ciaraldi T, Henry RR: Adiponectin: more than just another fat cell hormone?Diabetes Care 2003, 26:2442-2450). The adiponectin gene is located in chromosome 3q27, a susceptibility locus for T2DM and metabolic disorders (Saito K, Tobe T, Minoshima S, Asakawa S, Sumiya J, Yoda M, Nakano Y, Shimizu N, Tomita M: Organization of the gene for gelatin-binding protein (GBP28). Gene 1999, 229:67-73). Increased circulating levels of adiponectin are associated with improvement in the metabolic syndrome and reductions are strongly predictive of diabetes risk (Li S, Shin HJ, Ding EL, van Dam RM: Adiponectin levels and risk of type 2 diabetes: a systematic review and meta-analysis. JAMA 2009, 302:179-188. Extensive efforts have been made to understand how adiponectin levels can be elevated. The complex post-translational processing and secretion of adiponectin provides a rich area where pharmacologic manipulation may be developed to increase adiponectin levels in humans. Circulating adiponectin levels are increased by many commonly used drugs, such as statins, angiotensin converting enzyme (ACE) inhibitors, and thiazolidinediones (TZDs) providing an important opportunity to gain insight into the mechanisms underlying their effects. This review describes the cellular processes by which adiponectin is synthesized and secreted, current therapeutics known to affect this pathway and the potential for therapeutic manipulation in human subjects.