Genome-wide analysis of Smad and Schnurri transcription factors in C. elegans demonstrates widespread interaction and a function in collagen secretion.

Smads and their transcription factor partners mediate the transcriptional responses of target cells to secreted ligands of the Transforming Growth Factor-ß (TGF-ß) family, including those of the conserved bone morphogenetic protein (BMP) family, yet only a small number of direct target genes have been well characterized. In C. elegans, the BMP2/4 ortholog DBL-1 regulates multiple biological functions, including body size, via a canonical receptor-Smad signaling cascade. Here, we identify functional binding sites for SMA-3/Smad and its transcriptional partner SMA-9/Schnurri based on ChIP-seq peaks (identified by modEncode) and expression differences of nearby genes identified from RNA-seq analysis of corresponding mutants. We found that SMA-3 and SMA-9 have both overlapping and unique target genes. At a genome-wide scale, SMA-3/Smad acts as a transcriptional activator, whereas SMA-9/Schnurri direct targets include both activated and repressed genes. Mutations in sma-9 partially suppress the small body size phenotype of sma-3, suggesting some level of antagonism between these factors and challenging the prevailing model for Schnurri function. A functional analysis of target genes revealed a novel role in body size for genes involved in one-carbon metabolism and in the endoplasmic reticulum (ER) secretory pathway, including the disulfide reductase dpy-11. Our findings indicate that Smads and SMA-9/Schnurri have previously unappreciated complex genetic and genomic regulatory interactions that in turn regulate the secretion of extracellular components like collagen into the cuticle to mediate body size regulation.

The hypoxia response pathway promotes PEP carboxykinase and gluconeogenesis in C. elegans.

Actively dividing cells, including some cancers, rely on aerobic glycolysis rather than oxidative phosphorylation to generate energy, a phenomenon termed the Warburg effect. Constitutive activation of the Hypoxia Inducible Factor (HIF-1), a transcription factor known for mediating an adaptive response to oxygen deprivation (hypoxia), is a hallmark of the Warburg effect. HIF-1 is thought to promote glycolysis and suppress oxidative phosphorylation. Here, we instead show that HIF-1 can promote gluconeogenesis. Using a multiomics approach, we reveal the genomic, transcriptomic, and metabolomic landscapes regulated by constitutively active HIF-1 in C. elegans. We use RNA-seq and ChIP-seq under aerobic conditions to analyze mutants lacking EGL-9, a key negative regulator of HIF-1. We integrate these approaches to identify over two hundred genes directly and functionally upregulated by HIF-1, including the PEP carboxykinase PCK-1, a rate-limiting mediator of gluconeogenesis. This activation of PCK-1 by HIF-1 promotes survival in response to both oxidative and hypoxic stress. Our work identifies functional direct targets of HIF-1 in vivo, comprehensively describing the metabolome induced by HIF-1 activation in an organism.

Bone morphogenetic protein signaling regulation of AMPK and PI3K in lung cancer cells and C. elegans.

BACKGROUND: Bone morphogenetic protein (BMP) is a phylogenetically conserved signaling pathway required for development that is aberrantly expressed in several age-related diseases including cancer, Alzheimer's disease, obesity, and cardiovascular disease. Aberrant BMP signaling in mice leads to obesity, suggesting it may alter normal metabolism. The role of BMP signaling regulating cancer metabolism is not known. METHODS: To examine BMP regulation of metabolism, C. elegans harboring BMP gain-of-function (gof) and loss-of-function (lof) mutations were examined for changes in activity of catabolic and anabolic metabolism utilizing Western blot analysis and fluorescent reporters. AMP activated kinase (AMPK) gof and lof mutants were used to examine AMPK regulation of BMP signaling. H1299 (LKB1 wild-type), A549 (LKB1 lof), and A549-LKB1 (LKB1 restored) lung cancer cell lines were used to study BMP regulation of catabolic and anabolic metabolism. Studies were done using recombinant BMP ligands to activate BMP signaling, and BMP receptor specific inhibitors and siRNA to inhibit signaling. RESULTS: BMP signaling in both C. elegans and cancer cells is responsive to nutrient conditions. In both C. elegans and lung cancer cell lines BMP suppressed AMPK, the master regulator of catabolism, while activating PI3K, a regulator of anabolism. In lung cancer cells, inhibition of BMP signaling by siRNA or small molecules increased AMPK activity, and this increase was mediated by activation of LKB1. BMP2 ligand suppressed AMPK activation during starvation. BMP2 ligand decreased expression of TCA cycle intermediates and non-essential amino acids in H1299 cells. Furthermore, we show that BMP activation of PI3K is mediated through BMP type II receptor. We also observed feedback signaling, as AMPK suppressed BMP signaling, whereas PI3K increased BMP signaling. CONCLUSION: These studies show that BMP signaling suppresses catabolic metabolism and stimulates anabolic metabolism. We identified feedback mechanisms where catabolic induced signaling mediated by AMPK negatively regulates BMP signaling, whereas anabolic signaling produces a positive feedback regulation of BMP signing through Akt. These mechanisms were conserved in both lung cancer cells and C. elegans. These studies suggest that aberrant BMP signaling causes dysregulation of metabolism that is a potential mechanism by which BMP promotes survival of cancer cells.

Bone morphogenetic protein receptor 2 inhibition destabilizes microtubules promoting the activation of lysosomes and cell death of lung cancer cells.

BACKGROUND: Recent studies have shown that bone morphogenetic protein receptor 2 (BMPR2) regulates cell survival signaling events in cancer cells independent of the BMP type 1 receptor (BMPR1) or the Smad-1/5 transcription factor. Mutations in BMPR2 trafficking proteins leads to overactive BMP signaling, which leads to neurological diseases caused by BMPR2 stabilization of the microtubules. It is not known whether BMPR2 regulates the microtubules in cancer cells and what effect this has on cell survival. It is also not known whether alterations in BMPR2 trafficking effects activity and response to BMPR2 inhibitors. METHODS: We utilized BMPR2 siRNA and the BMP receptor inhibitors JL5 and Ym155, which decrease BMPR2 signaling and cause its mislocalization to the cytoplasm. Using the JL5 resistant MDA-MD-468 cell line and sensitive lung cancer cell lines, we examined the effects of BMPR2 inhibition on BMPR2 mislocalization to the cytoplasm, microtubule destabilization, lysosome activation and cell survival. RESULTS: We show that the inhibition of BMPR2 destabilizes the microtubules. Destabilization of the microtubules leads to the activation of the lysosomes. Activated lysosomes further decreases BMPR2 signaling by causing it to mislocalizated to the cytoplasm and/or lysosome for degradation. Inhibition of the lysosomes with chloroquine attenuates BMPR2 trafficking to the lysosome and cell death induced by BMPR2 inhibitors. Furthermore, in MDA-MD-468 cells that are resistant to JL5 induced cell death, BMPR2 was predominately located in the cytoplasm. BMPR2 failed to localize to the cytoplasm and/or lysosome following treatment with JL5 and did not destabilize the microtubules or activate the lysosomes. CONCLUSIONS: These studies reveal that the inhibition of BMPR2 destabilizes the microtubules promoting cell death of cancer cells that involves the activation of the lysosomes. Resistance to small molecules targeting BMPR2 may occur if the BMPR2 is localized predominantly to the cytoplasm and/or fails to localize to the lysosome for degradation. Video Abstract.

Biogenic amine neurotransmitters promote eicosanoid production and protein homeostasis.

Metazoans use protein homeostasis (proteostasis) pathways to respond to adverse physiological conditions, changing environment, and aging. The nervous system regulates proteostasis in different tissues, but the mechanism is not understood. Here, we show that Caenorhabditis elegans employs biogenic amine neurotransmitters to regulate ubiquitin proteasome system (UPS) proteostasis in epithelia. Mutants for biogenic amine synthesis show decreased poly-ubiquitination and turnover of a GFP-based UPS substrate. Using RNA-seq and mass spectrometry, we found that biogenic amines promote eicosanoid production from poly-unsaturated fats (PUFAs) by regulating expression of cytochrome P450 monooxygenases. Mutants for one of these P450s share the same UPS phenotype observed in biogenic amine mutants. The production of n-6 eicosanoids is required for UPS substrate turnover, whereas accumulation of n-6 eicosanoids accelerates turnover. Our results suggest that sensory neurons secrete biogenic amines to modulate lipid signaling, which in turn activates stress response pathways to maintain UPS proteostasis.

Genetic interactions between the DBL-1/BMP-like pathway and dpy body size-associated genes in Caenorhabditis elegans.

Bone morphogenetic protein (BMP) signaling pathways control many developmental and homeostatic processes, including cell size and extracellular matrix remodeling. An understanding of how this pathway itself is controlled remains incomplete. To identify novel regulators of BMP signaling, we performed a forward genetic screen in Caenorhabditis elegans for genes involved in body size regulation, a trait under the control of BMP member DBL-1. We isolated mutations that suppress the long phenotype of lon-2, a gene that encodes a negative regulator that sequesters DBL-1. This screen was effective because we isolated alleles of several core components of the DBL-1 pathway, demonstrating the efficacy of the screen. We found additional alleles of previously identified but uncloned body size genes. Our screen also identified widespread involvement of extracellular matrix proteins in DBL-1 regulation of body size. We characterized interactions between the DBL-1 pathway and extracellular matrix and other genes that affect body morphology. We discovered that loss of some of these genes affects the DBL-1 pathway, and we provide evidence that DBL-1 signaling affects many molecular and cellular processes associated with body size. We propose a model in which multiple body size factors are controlled by signaling through the DBL-1 pathway and by DBL-1-independent processes.

Human Marfan and Marfan-like Syndrome associated mutations lead to altered trafficking of the Type II TGFß receptor in Caenorhabditis elegans.

The transforming growth factor-ß (TGFß) family plays an important role in many developmental processes and when mutated often contributes to various diseases. Marfan syndrome is a genetic disease with an occurrence of approximately 1 in 5,000. The disease is caused by mutations in fibrillin, which lead to an increase in TGFß ligand activity, resulting in abnormalities of connective tissues which can be life-threatening. Mutations in other components of TGFß signaling (receptors, Smads, Schnurri) lead to similar diseases with attenuated phenotypes relative to Marfan syndrome. In particular, mutations in TGFß receptors, most of which are clustered at the C-terminal end, result in Marfan-like (MFS-like) syndromes. Even though it was assumed that many of these receptor mutations would reduce or eliminate signaling, in many cases signaling is active. From our previous studies on receptor trafficking in C. elegans, we noticed that many of these receptor mutations that lead to Marfan-like syndromes overlap with mutations that cause mis-trafficking of the receptor, suggesting a link between Marfan-like syndromes and TGFß receptor trafficking. To test this hypothesis, we introduced three of these key MFS and MFS-like mutations into the C. elegans TGFß receptor and asked if receptor trafficking is altered. We find that in every case studied, mutated receptors mislocalize to the apical surface rather than basolateral surface of the polarized intestinal cells. Further, we find that these mutations result in longer animals, a phenotype due to over-stimulation of the nematode TGFß pathway and, importantly, indicating that function of the receptor is not abrogated in these mutants. Our nematode models of Marfan syndrome suggest that MFS and MFS-like mutations in the type II receptor lead to mis-trafficking of the receptor and possibly provides an explanation for the disease, a phenomenon which might also occur in some cancers that possess the same mutations within the type II receptor (e.g. colon cancer).

bantam microRNA is a negative regulator of the Drosophila decapentaplegic pathway.

Decapentaplegic (Dpp), the Drosophila homolog of the vertebrate bone morphogenetic protein (BMP2/4), is crucial for patterning and growth in many developmental contexts. The Dpp pathway is regulated at many different levels to exquisitely control its activity. We show that bantam (ban), a microRNA, modulates Dpp signaling activity. Over expression of ban decreases phosphorylated Mothers against decapentaplegic (Mad) levels and negatively affects Dpp pathway transcriptional target genes, while null mutant clones of ban upregulate the pathway. We provide evidence that dpp upregulates ban in the wing imaginal disc, and attenuation of Dpp signaling results in a reduction of ban expression, showing that they function in a feedback loop. Furthermore, we show that this feedback loop is important for maintaining anterior-posterior compartment boundary stability in the wing disc through regulation of optomotor blind (omb), a known target of the pathway. Our results support a model that ban functions with dpp in a negative feedback loop.

C. elegans SMA-10 regulates BMP receptor trafficking.

Signal transduction of the conserved transforming growth factor-ß (TGFß) family signaling pathway functions through two distinct serine/threonine transmembrane receptors, the type I and type II receptors. Endocytosis orchestrates the assembly of signaling complexes by coordinating the entry of receptors with their downstream signaling mediators. Recently, we showed that the C. elegans type I bone morphogenetic protein (BMP) receptor SMA-6, part of the TGFß family, is recycled through the retromer complex while the type II receptor, DAF-4 is recycled in a retromer-independent, ARF-6 dependent manner. From genetic screens in C. elegans aimed at identifying new modifiers of BMP signaling, we reported on SMA-10, a conserved LRIG (leucine-rich and immunoglobulin-like domains) transmembrane protein. It is a positive regulator of BMP signaling that binds to the SMA-6 receptor. Here we show that the loss of sma-10 leads to aberrant endocytic trafficking of SMA-6, resulting in its accumulation in distinct intracellular endosomes including the early endosome, multivesicular bodies (MVB), and the late endosome with a reduction in signaling strength. Our studies show that trafficking defects caused by the loss of sma-10 are not universal, but affect only a limited set of receptors. Likewise, in Drosophila, we find that the fly homolog of sma-10, lambik (lbk), reduces signaling strength of the BMP pathway, consistent with its function in C. elegans and suggesting evolutionary conservation of function. Loss of sma-10 results in reduced ubiquitination of the type I receptor SMA-6, suggesting a possible mechanism for its regulation of BMP signaling.

Efficient Screening of CRISPR/Cas9-Induced Events in Drosophila Using a Co-CRISPR Strategy.

Genome editing using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and associated nuclease (Cas9) enables specific genetic modifications, including deletions, insertions, and substitutions in numerous organisms, such as the fruit fly Drosophila melanogaster One challenge of the CRISPR/Cas9 system can be the laborious and time-consuming screening required to find CRISPR-induced modifications due to a lack of an obvious phenotype and low frequency after editing. Here we apply the successful co-CRISPR technique in Drosophila to simultaneously target a gene of interest and a marker gene, ebony, which is a recessive gene that produces dark body color and has the further advantage of not being a commonly used transgenic marker. We found that Drosophila broods containing higher numbers of CRISPR-induced ebony mutations ("jackpot" lines) are significantly enriched for indel events in a separate gene of interest, while broods with few or no ebony offspring showed few mutations in the gene of interest. Using two different PAM sites in our gene of interest, we report that ∼61% (52-70%) of flies from the ebony-enriched broods had an indel in DNA near either PAM site. Furthermore, this marker mutation system may be useful in detecting the less frequent homology-directed repair events, all of which occurred in the ebony-enriched broods. By focusing on the broods with a significant number of ebony flies, successful identification of CRISPR-induced events is much faster and more efficient. The co-CRISPR technique we present significantly improves the screening efficiency in identification of genome-editing events in Drosophila.

CeleST: computer vision software for quantitative analysis of C. elegans swim behavior reveals novel features of locomotion.

In the effort to define genes and specific neuronal circuits that control behavior and plasticity, the capacity for high-precision automated analysis of behavior is essential. We report on comprehensive computer vision software for analysis of swimming locomotion of C. elegans, a simple animal model initially developed to facilitate elaboration of genetic influences on behavior. C. elegans swim test software CeleST tracks swimming of multiple animals, measures 10 novel parameters of swim behavior that can fully report dynamic changes in posture and speed, and generates data in several analysis formats, complete with statistics. Our measures of swim locomotion utilize a deformable model approach and a novel mathematical analysis of curvature maps that enable even irregular patterns and dynamic changes to be scored without need for thresholding or dropping outlier swimmers from study. Operation of CeleST is mostly automated and only requires minimal investigator interventions, such as the selection of videotaped swim trials and choice of data output format. Data can be analyzed from the level of the single animal to populations of thousands. We document how the CeleST program reveals unexpected preferences for specific swim "gaits" in wild-type C. elegans, uncovers previously unknown mutant phenotypes, efficiently tracks changes in aging populations, and distinguishes "graceful" from poor aging. The sensitivity, dynamic range, and comprehensive nature of CeleST measures elevate swim locomotion analysis to a new level of ease, economy, and detail that enables behavioral plasticity resulting from genetic, cellular, or experience manipulation to be analyzed in ways not previously possible.

Deletion of microRNA-80 activates dietary restriction to extend C. elegans healthspan and lifespan.

Caloric/dietary restriction (CR/DR) can promote longevity and protect against age-associated disease across species. The molecular mechanisms coordinating food intake with health-promoting metabolism are thus of significant medical interest. We report that conserved Caenorhabditis elegans microRNA-80 (mir-80) is a major regulator of the DR state. mir-80 deletion confers system-wide healthy aging, including maintained cardiac-like and skeletal muscle-like function at advanced age, reduced accumulation of lipofuscin, and extended lifespan, coincident with induction of physiological features of DR. mir-80 expression is generally high under ad lib feeding and low under food limitation, with most striking food-sensitive expression changes in posterior intestine. The acetyltransferase transcription co-factor cbp-1 and interacting transcription factors daf-16/FOXO and heat shock factor-1 hsf-1 are essential for mir-80(Δ) benefits. Candidate miR-80 target sequences within the cbp-1 transcript may confer food-dependent regulation. Under food limitation, lowered miR-80 levels directly or indirectly increase CBP-1 protein levels to engage metabolic loops that promote DR.

The CD225 domain of IFITM3 is required for both IFITM protein association and inhibition of influenza A virus and dengue virus replication.

The interferon-induced transmembrane protein 3 (IFITM3) gene is an interferon-stimulated gene that inhibits the replication of multiple pathogenic viruses in vitro and in vivo. IFITM3 is a member of a large protein superfamily, whose members share a functionally undefined area of high amino acid conservation, the CD225 domain. We performed mutational analyses of IFITM3 and identified multiple residues within the CD225 domain, consisting of the first intramembrane domain (intramembrane domain 1 [IM1]) and a conserved intracellular loop (CIL), that are required for restriction of both influenza A virus (IAV) and dengue virus (DENV) infection in vitro. Two phenylalanines within IM1 (F75 and F78) also mediate a physical association between IFITM proteins, and the loss of this interaction decreases IFITM3-mediated restriction. By extension, similar IM1-mediated associations may contribute to the functions of additional members of the CD225 domain family. IFITM3's distal N-terminal domain is also needed for full antiviral activity, including a tyrosine (Y20), whose alteration results in mislocalization of a portion of IFITM3 to the cell periphery and surface. Comparative analyses demonstrate that similar molecular determinants are needed for IFITM3's restriction of both IAV and DENV. However, a portion of the CIL including Y99 and R87 is preferentially needed for inhibition of the orthomyxovirus. Several IFITM3 proteins engineered with rare single-nucleotide polymorphisms demonstrated reduced expression or mislocalization, and these events were associated with enhanced viral replication in vitro, suggesting that possessing such alleles may impact an individual's risk for viral infection. On the basis of this and other data, we propose a model for IFITM3-mediated restriction.

Sitagliptin exerts an antinflammatory action.

CONTEXT: Sitagliptin is an inhibitor of the enzyme dipeptidyl peptidase-IV (DPP-IV), which degrades the incretins, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, and thus, sitagliptin increases their bioavailability. The stimulation of insulin and the suppression of glucagon secretion that follow exert a glucose lowering effect and hence its use as an antidiabetic drug. Because DPP-IV is expressed as CD26 on cell membranes and because CD26 mediates proinflammatory signals, we hypothesized that sitagliptin may exert an antiinflammatory effect. PATIENTS AND METHODS: Twenty-two patients with type 2 diabetes were randomized to receive either 100 mg daily of sitagliptin or placebo for 12 wk. Fasting blood samples were obtained at baseline and at 2, 4, and 6 hours after a single dose of sitagliptin and at 2, 4, 8, and 12 wk of treatment. RESULTS: Glycosylated hemoglobin fell significantly from 7.6 ± 0.4 to 6.9 ± 3% in patients treated with sitagliptin. Fasting glucagon-like peptide-1 concentrations increased significantly, whereas the mRNA expression in mononuclear cell of CD26, the proinflammatory cytokine, TNFα, the receptor for endotoxin, Toll-like receptor (TLR)-4, TLR-2, and proinflammatory kinases, c-Jun N-terminal kinase-1 and inhibitory-κB kinase (IKKß), and that of the chemokine receptor CCR-2 fell significantly after 12 wk of sitagliptin. TLR-2, IKKß, CCR-2, and CD26 expression and nuclear factor-κB binding also fell after a single dose of sitagliptin. There was a fall in protein expression of c-Jun N-terminal kinase-1, IKKß, and TLR-4 and in plasma concentrations of C-reactive protein, IL-6, and free fatty acids after 12 wk of sitagliptin. CONCLUSIONS: These effects are consistent with a potent and rapid antiinflammatory effect of sitagliptin and may potentially contribute to the inhibition of atherosclerosis. The suppression of CD26 expression suggests that sitagliptin may inhibit the synthesis of DPP-IV in addition to inhibiting its action.

Exenatide exerts a potent antiinflammatory effect.

OBJECTIVE: Our objective was to determine whether exenatide exerts an antiinflammatory effect. RESEARCH DESIGN AND METHODS: Twenty-four patients were prospectively randomized to be injected sc with either exenatide 10 µg twice daily [n = 12; mean age = 56 ± 3 yr; mean body mass index = 39.8 ± 2 kg/m(2); mean glycosylated hemoglobin (HbA1c) = 8.6 ± 0.4%] or placebo twice daily (n = 12; mean age = 54 ± 4 yr; mean body mass index = 39.1 ± 1.6 kg/m(2); mean HbA1c = 8.5 ± 0.3%) for 12 wk. Fasting blood samples were obtained at 0, 3, 6, and 12 wk. Blood samples were also collected for up to 6 h after a single dose of exenatide (5 µg) or placebo. RESULTS: Fasting blood glucose fell from 139 ± 17 to 110 ± 9 mg/dl, HbA1c from 8.6 ± 0.4 to 7.4 ± 0.5% (P < 0.05), and free fatty acids by 21 ± 5% from baseline (P < 0.05) with exenatide. There was no weight loss. There was a significant reduction in reactive oxygen species generation and nuclear factor-κB binding by 22 ± 9 and 26 ± 7%, respectively, and the mRNA expression of TNFα, IL-1ß, JNK-1, TLR-2, TLR-4, and SOCS-3 in mononuclear cells by 31 ± 12, 22 ± 10, 20 ± 11, 22 ± 9, 16 ± 7, and 31 ± 10%, respectively (P < 0.05 for all) after 12 wk of exenatide. After a single injection of exenatide, there was a reduction by 20 ± 7% in free fatty acids, 19 ± 7% in reactive oxygen species generation, 39 ± 11% in nuclear factor-κB binding, 18 ± 9% in TNFα expression, 26 ± 7% in IL-1ß expression, 18 ± 7% in JNK-1 expression, 24 ± 12% in TLR-4 expression, and 23 ± 11% in SOCS-3 expression (P < 0.05 for all). The plasma concentrations of monocyte chemoattractant protein-1, matrix metalloproteinase-9, serum amyloid A, and IL-6 were suppressed after 12 wk exenatide treatment by 15 ± 7, 20 ± 11, 16 ± 7, and 22 ± 12%, respectively (P < 0.05 for all). CONCLUSIONS: Exenatide exerts a rapid antiinflammatory effect at the cellular and molecular level. This may contribute to a potentially beneficial antiatherogenic effect. This effect was independent of weight loss.

Low estradiol concentrations in men with subnormal testosterone concentrations and type 2 diabetes.

OBJECTIVE: It has been suggested that the high prevalence of subnormal free testosterone concentrations, along with low or inappropriately normal gonadotropins in men with type 2 diabetes, may be the result of an increase in plasma estradiol concentrations secondary to an increase in aromatase activity in the adipose tissue that leads to the suppression of the hypothalamo-hypophyseal-gonadal axis. RESEARCH DESIGN AND METHODS: To investigate this hypothesis, plasma estradiol, testosterone, leutinizing hormone, follicle-stimulating hormone, and sex hormone-binding globulin (SHBG) concentrations were measured in fasting blood samples of 240 men with type 2 diabetes. Free estradiol concentrations were either calculated (n = 198) using total estradiol and SHBG measured by immunoassay or directly measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) and equilibrium dialysis (n = 102). RESULTS: The calculated free estradiol concentration in men with subnormal free testosterone concentrations was lower than that in men with normal free testosterone concentrations (median 0.047 vs. 0.063 ng/dL, P < 0.001). Directly measured (LC-MS/MS) free estradiol concentrations were also lower in men with subnormal free testosterone concentrations (median 0.025 vs. 0.045 ng/dL, P = 0.008). Free estradiol concentrations were directly related to free testosterone but not to BMI or age. CONCLUSIONS: These data show that the suppression of the hypothalamo-hypophyseal-gonadal axis in patients with subnormal free testosterone concentrations and type 2 diabetes is not associated with increased estradiol concentrations. The pathogenesis of subnormal free testosterone concentrations in type 2 diabetes needs to be investigated further.

Liraglutide as additional treatment for type 1 diabetes.

OBJECTIVE: To determine whether the addition of liraglutide to insulin to treat patients with type 1 diabetes leads to an improvement in glycemic control and diminish glycemic variability. SUBJECTS AND METHODS: In this study, 14 patients with well-controlled type 1 diabetes on continuous glucose monitoring and intensive insulin therapy were treated with liraglutide for 1 week. Of the 14 patients, eight continued therapy for 24 weeks. RESULTS: In all the 14 patients, mean fasting and mean weekly glucose concentrations significantly decreased after 1 week from 130±10 to 110±8  mg/dl (P<0.01) and from 137.5±20 to 115±12  mg/dl (P<0.01) respectively. Glycemic excursions significantly improved at 1 week. The mean s.d. of glucose concentrations decreased from 56±10 to 26±6  mg/dl (P<0.01) and the coefficient of variation decreased from 39.6±10 to 22.6±7 (P<0.01). There was a concomitant fall in the basal insulin from 24.5±6 to 16.5±6 units (P<0.01) and bolus insulin from 22.5±4 to 15.5±4 units (P<0.01). In patients who continued therapy with liraglutide for 24 weeks, mean fasting, mean weekly glucose concentrations, glycemic excursions, and basal and bolus insulin dose also significantly decreased (P<0.01). HbA1c decreased significantly at 24 weeks from 6.5 to 6.1% (P=0.02), as did the body weight by 4.5±1.5  kg (P=0.02). CONCLUSION: Liraglutide treatment provides an additional strategy for improving glycemic control in type 1 diabetes. It also leads to weight loss.

Durability of effects of exenatide treatment on glycemic control, body weight, systolic blood pressure, C-reactive protein, and triglyceride concentrations.

OBJECTIVE: To determine (1) whether long-term treatment with exenatide is associated with reductions in C-reactive protein (CRP), systolic blood pressure (BP), and triglyceride concentrations in addition to reductions in body weight and hemoglobin A(1c) (A1C) levels and (2) whether these beneficial results persist without any loss of effect while exenatide is being used, and whether they reverse after its cessation. METHODS: We conducted a retrospective review of 141 patients with type 2 diabetes mellitus treated with exenatide at a tertiary clinic. RESULTS: Exenatide (mean duration of treatment, 1.4 years) decreased A1C (0.7%), weight (5 kg), systolic BP (8 mm Hg), and triglyceride concentrations (46 mg/dL) (P<.05 for all). Sixty-one patients continued exenatide therapy throughout the study (mean duration of use, 2.4 years). Exenatide treatment reduced their mean weight by 7 kg, systolic BP by 8 mm Hg, triglycerides by 52 mg/dL, A1C by 1.3%, and CRP by 2.4 mg/L (P<.05 for all). Reductions in systolic BP and CRP were not related to weight loss. The reduction in CRP concentration was significantly related to the baseline CRP concentration (r = 0.78; P<.001) and to change in A1C (r = 0.68; P = .02). Patients who stopped taking exenatide had a reversal of the benefits within 6 months after cessation of treatment. CONCLUSION: Exenatide treatment in patients with type 2 diabetes has durable and persistent beneficial effects on A1C, weight, CRP, systolic BP, and triglyceride concentrations. Cessation of treatment reverses all these beneficial effects within 6 months. There was no evidence of loss of its effects while exenatide treatment was continued.