miRNAs are important metabolic regulators and are altered at both the cellular and secreted levels in diseases, including type 2 diabetes (T2D). However, to what extent these alterations are in response to factors in the in vivo milieu or are cell-intrinsic remains unclear. Here we used a disease-in-a-dish model in which iPSCs from T2D patients and controls were differentiated into myoblasts (iMyos), and their cellular and secreted miRNAs were profiled. We found that iMyos from T2D donors exhibit cell-intrinsic alterations in miRNA expression and secretion in small extracellular vesicles (sEVs)/exosomes. Integrating miRNA-predicted targets with transcriptomic and proteomic data revealed that miRNAs altered in T2D iMyos were associated with coordinated changes in their predicted targets, but with a much greater impact on protein than on mRNA levels. This effect was validated by miRNA overexpression in control iMyos. The upregulated miRNAs targeted pathways related to aerobic respiration, membrane trafficking, and RNA metabolism. Even more marked changes were observed in sEV-associated miRNAs secreted by T2D iMyos, indicative of T2D-associated effects on miRNA sorting and release. Target genes of secreted miRNAs altered in T2D iMyos were enriched in metabolic pathways including insulin signaling and mitochondrial metabolism. Consistent with this, sEVs derived from control iMyos increased glucose uptake and mitochondrial function in recipient human white adipocytes, whereas sEVs from T2D iMyos did not. Thus, in T2D, muscle exhibits cell-intrinsic alterations in expression and secretion of miRNAs, which function as epigenetic regulators of protein expression locally, as well as potentially in distal tissues.

Hepatic insulin resistance is central to type 2 diabetes (T2D) and metabolic syndrome, but defining the molecular basis of this defect in humans is challenging because of limited tissue access. Utilizing inducible pluripotent stem cells differentiated into hepatocytes from control individuals and patients with T2D and liquid chromatography with tandem mass spectrometry-based (LC-MS/MS-based) phosphoproteomics analysis, we identified a large network of cell-intrinsic alterations in signaling in T2D. Over 300 phosphosites showed impaired or reduced insulin signaling, including losses in the classical insulin-stimulated PI3K/AKT cascade and their downstream targets. In addition, we identified over 500 phosphosites of emergent, i.e., new or enhanced, signaling. These occurred on proteins involved in the Rho-GTPase pathway, RNA metabolism, vesicle trafficking, and chromatin modification. Kinome analysis indicated that the impaired phosphorylation sites represented reduced actions of AKT2/3, PKCθ, CHK2, PHKG2, and/or STK32C kinases. By contrast, the emergent phosphorylation sites were predicted to be mediated by increased action of the Rho-associated kinases 1 and 2 (ROCK1/2), mammalian STE20-like protein kinase 4 (MST4), and/or branched-chain α-ketoacid dehydrogenase kinase (BCKDK). Inhibiting ROCK1/2 activity in T2D induced pluripotent stem cell-derived hepatocytes restored some of the alterations in insulin action. Thus, insulin resistance in the liver in T2D did not simply involve a loss of canonical insulin signaling but the also appearance of new phosphorylations representing a change in the balance of multiple kinases. Together, these led to altered insulin action in the liver and identified important targets for the therapy of hepatic insulin resistance.

MicroRNAs are important regulators of metabolism in health and disease, and alterations in miRNAs can impact key metabolic pathways/processes, including insulin signaling, beta cell function, and fat/liver function. miRNAs are also secreted from cells in exosomes or small extracellular vesicles (sEVs) which can be taken up and regulate gene/protein expression in cells at a distance. To determine how T2D can modify the expression of cellular and sEV-secreted miRNAs, we have used a disease-in-a-dish model in which iPS cells from T2D patients and controls were differentiated into myoblasts (iMyos), and cellular and secreted sEV miRNAs assessed using a nuclease protection assay, which assesses all known human miRNAs. We show that, compared to controls, iMyos from T2D in vitro exhibit significant alterations in cellular expression of 71 miRNAs, with 22 up-regulated and 49 down-regulated. Overlapping the predicted miRNA-targets of the up-regulated miRNAs with global proteomics data revealed 123 proteins that were targeted and down-regulated by these miRNAs, consistent with the fact that a single miRNA has multiple targets and indicating that T2D-induced alterations in miRNA expression contribute to broad range of changes in cellular protein. In the sEVs secreted from iMyo, there were even more marked changes, with 70 up- and 296 down-regulated miRNAs, demonstrating a major alteration in regulation of miRNA secretion by muscle in T2D. Importantly, most of the T2D-regulated sEV are known to be involved in the development of insulin resistance and T2D. For example, levels of miR-1299, miR-1324, and miR-378h were elevated in T2D-derived sEVs, and we show that these miRNAs can suppress gene expression of PTEN, PGC-1α/β and FASN in adipose tissue. The dysregulated miRNA expression and secretion contribute to altered gene/protein expression in the myoblast itself, as well as targeting metabolic and signaling genes in other tissues, such as adipose tissue, thereby contributing to the pathogenesis of T2D. Disclosure A. Nawaz: None. M. Lino: None. A. Gattu: None. N. Haider: None. C. Kahn: Consultant; Cellarity. Other Relationship; 1825 Therapeutics. Advisory Panel; TIXiMED, Senseion, ERX.

Hepatic insulin resistance is central to type 2 diabetes (T2D), fatty liver disease, and metabolic syndrome. To identify the fundamental, cell-autonomous defects underlying hepatic insulin resistance in T2D, we have used inducible human pluripotent stem (iPS) cells derived from 16 individuals with and without T2D differentiated to hepatocytes (iHeps) and studied in vitro. Consistent with pathway selective insulin resistance, we find that insulin failed to suppress gene expression of critical gluconeogenic enzymes (PCK1, G6PC) but continued to stimulate increased expression of the lipogenic enzymes, fatty acid synthase and acetyl Co-A carboxylase 1 in T2D iHeps. iHeps from T2D also displayed reduced insulin receptor tyrosine phosphorylation and reduced phosphorylation through the IRS/Akt pathway. Global phosphoproteomics in control and T2D iHeps identified 378 unique phosphosites regulated by insulin, and many dysregulated phosphosites within the classical insulin signaling pathway (IRS, AKT1/2, GSK3, FOXO1, RPS6KB1, TSC2) and components of gene transcription regulation, membrane trafficking, Rho-GTPases, vesicle transport. Using a kinome-wide data set created with synthetic peptide libraries to profile almost all functional known human serine/threonine kinases, we found the alterations in insulin signaling mapped to AKT, P70S6K, P90S6K, RSK, PKCτ, and SGK kinases. Thus, iHeps from T2D patients show pathway-selective insulin resistance with a loss of suppression of gluconeogenesis by insulin yet persistent activation of lipogenesis, even in vitro, in the absence of any circulating factor exposure. T2D iHeps also show a dysregulated phosphorylation network that provides new clues to the kinases whose action is altered in T2D and hepatic insulin resistance. Disclosure A.Gattu: None. A.Krook: None. J.R.Zierath: None. M.Mann: None. C.Kahn: None. Funding National Institutes of Health (T32DK007260-46)

Insulin and IGF-1 receptors (IR and IGF1R) are highly homologous and share similar signaling systems, but each has a unique physiological role, with IR primarily regulating metabolic homeostasis and IGF1R regulating mitogenic control and growth. Here, we show that replacement of a single amino acid at position 973, just distal to the NPEY motif in the intracellular juxtamembrane region, from leucine, which is highly conserved in IRs, to phenylalanine, the highly conserved homologous residue in IGF1Rs, resulted in decreased IRS-1/PI3K/Akt/mTORC1 signaling and increased Shc/Gab1/MAPK cell cycle signaling. As a result, cells expressing L973F-IR exhibited decreased insulin-induced glucose uptake, increased cell growth, and impaired receptor internalization. Mice with knockin of the L973F-IR showed similar alterations in signaling in vivo, and this led to decreased insulin sensitivity, a modest increase in growth, and decreased weight gain when mice were challenged with a high-fat diet. Thus, leucine-973 in the juxtamembrane region of the IR acts as a crucial residue differentiating IR signaling from IGF1R signaling.

The circulating concentrations of total and free testosterone vary substantially in people over time due to biologic factors as well as due to measurement variation. Accurate measurement of total and free testosterone is essential for making the diagnosis of androgen disorders. Total testosterone should ideally be measured in a fasting state in the morning using a reliable assay, such as liquid chromatography tandem mass spectrometry, in a laboratory that is certified by an accuracy-based benchmark. Free testosterone levels should be measured in men in whom alterations in binding protein concentrations are suspected or in whom total testosterone levels are only slightly above or slightly below the lower limit of the normal male range for testosterone.

Aging is associated with a progressive decrease in skeletal muscle mass, strength and power and impairment of physical function. Serum testosterone concentrations in men decrease with advancing age due to defects at all levels of the hypothalamic-pituitary–testicular axis. Testosterone administration increases skeletal muscle mass, strength and power in older men with low or low normal testosterone levels, but the effects on performance-based measures of physical function have been inconsistent. Adequately powered randomized trials are needed to determine the long-term safety and efficacy of testosterone in improving physical function and quality of life in older adults with functional limitations.

The increased hepatic gluconeogenesis in type 2 diabetes mellitus has often been ascribed to increased transcription of phosphoenolpyruvate carboxykinase 1, cystolic form (PEPCK1), although recent evidence has questioned this attribution. To assess the metabolic role of PEPCK1, we treated regular chow fed and high-fat fed (HFF) male Sprague-Dawley rats with a 2'-O-methoxyethyl chimeric antisense oligonucleotide (ASO) against PEPCK1 and compared them with control ASO-treated rats. PEPCK1 ASO effectively decreased PEPCK1 expression in the liver and white adipose tissue. In chow fed rats, PEPCK1 ASO did not alter adiposity, plasma glucose, or insulin. In contrast, PEPCK1 ASO decreased the white adipose tissue mass in HFF rats but without altering basal rates of lipolysis, de novo lipogenesis, or glyceroneogenesis in vivo. Despite the protection from adiposity, hepatic insulin sensitivity was impaired in HFF PEPCK1 ASO-treated rats. PEPCK1 ASO worsened hepatic steatosis, although without additional impairments in hepatic insulin signaling or activation of inflammatory signals in the liver. Instead, the development of hepatic insulin resistance and the decrease in hepatic glycogen synthesis during a hyperglycemic clamp was attributed to a decrease in hepatic glucokinase (GCK) expression and decreased synthesis of glycogen via the direct pathway. The decrease in GCK expression was associated with increased expression of activating transcription factor 3, a negative regulator of GCK transcription. These studies have demonstrated that PEPCK1 is integral to coordinating cellular metabolism in the liver and adipose tissue, although it does not directly effect hepatic glucose production or adipose glyceroneogenesis.

Significance The paradox of selective hepatic insulin resistance, wherein the insulin-resistant liver fails to suppress glucose production but continues to produce triglycerides, is central to the pathophysiology of type 2 diabetes. We hypothesized that hepatic triglyceride synthesis is regulated mostly by fatty acid delivery to the liver and independent of changes in hepatic insulin signaling. To examine this hypothesis, we used a novel LC-MS/MS method to measure rates of hepatic fatty acid esterification in vivo. In contrast to hepatic de novo hepatic lipogenesis, rates of hepatic esterification of fatty acids into triglyceride was primarily dependent on fatty acid delivery and independent of hepatic insulin action, providing an explanation for increased hepatic triglyceride synthesis in the presence of hepatic insulin resistance.

The steroid receptor coactivator 1 (SRC1) regulates key metabolic pathways, including glucose homeostasis. SRC1(-/-) mice have decreased hepatic expression of gluconeogenic enzymes and a reduction in the rate of endogenous glucose production (EGP). We sought to determine whether decreasing hepatic and adipose SRC1 expression in normal adult rats would alter glucose homeostasis and insulin action. Regular chow-fed and high-fat-fed male Sprage-Dawley rats were treated with an antisense oligonucleotide (ASO) against SRC1 or a control ASO for 4 wk, followed by metabolic assessments. SRC1 ASO did not alter basal EGP or expression of gluconeogenic enzymes. Instead, SRC1 ASO increased insulin-stimulated whole body glucose disposal by ~30%, which was attributable largely to an increase in insulin-stimulated muscle glucose uptake. This was associated with an approximately sevenfold increase in adipose expression of lipocalin-type prostaglandin D2 synthase, a previously reported regulator of insulin sensitivity, and an approximately 70% increase in plasma PGD2 concentration. Muscle insulin signaling, AMPK activation, and tissue perfusion were unchanged. Although GLUT4 content was unchanged, SRC1 ASO increased the cleavage of tether-containing UBX domain for GLUT4, a regulator of GLUT4 translocation. These studies point to a novel role of adipose SRC1 as a regulator of insulin-stimulated muscle glucose uptake.

Pigment epithelium-derived factor (PEDF) is an antiinflammatory protein that circulates at high levels in the metabolic syndrome. Metabolic studies of PEDF knockout (KO) mice were conducted to investigate the relationship between PEDF, inflammatory markers, and metabolic homeostasis. Male PEDF KO mice demonstrated a phenotype consisting of increased adiposity, glucose intolerance, and elevated serum levels of metabolites associated with the metabolic syndrome. Genome expression analysis revealed an increase in IL-1β signaling in the livers of PEDF KO mice that was accompanied by impaired IRS and Akt signaling. In human hepatocytes, PEDF blocked the effects of an IL-1β challenge by suppressing activation of the inflammatory mediator c-Jun N-terminal kinase while restoring Akt signaling. RNA interference of PEDF in human hepatocytes was permissive for c-Jun N-terminal kinase activation and decreased Akt signaling. A metabolomics profile identified elevated circulating levels of tricarboxyclic acid cycle intermediates including succinate, an inducer of IL-1β, in PEDF KO mice. Succinate-dependent IL-1β expression was blocked by PEDF in PEDF KO, but not wild-type hepatocytes. In vivo, PEDF restoration reduced hyperglycemia and improved hepatic insulin signaling in PEDF KO mice. These findings identify elevated PEDF as a homeostatic mechanism in the human metabolic syndrome.

Binge drinking, the most common form of alcohol consumption, is associated with increased mortality and morbidity; yet, its biological consequences are poorly defined. Previous studies demonstrated that chronic alcohol use results in increased gut permeability and increased serum endotoxin levels that contribute to many of the biological effects of chronic alcohol, including alcoholic liver disease. In this study, we evaluated the effects of acute binge drinking in healthy adults on serum endotoxin levels. We found that acute alcohol binge resulted in a rapid increase in serum endotoxin and 16S rDNA, a marker of bacterial translocation from the gut. Compared to men, women had higher blood alcohol and circulating endotoxin levels. In addition, alcohol binge caused a prolonged increase in acute phase protein levels in the systemic circulation. The biological significance of the in vivo endotoxin elevation was underscored by increased levels of inflammatory cytokines, TNFα and IL-6, and chemokine, MCP-1, measured in total blood after in vitro lipopolysaccharide stimulation. Our findings indicate that even a single alcohol binge results in increased serum endotoxin levels likely due to translocation of gut bacterial products and disturbs innate immune responses that can contribute to the deleterious effects of binge drinking.

Aerobic exercise increases muscle glucose and improves insulin action through numerous pathways, including activation of Ca2+/calmodulin-dependent protein kinases (CAMKs) and peroxisome proliferator γ coactivator 1α (PGC-1α). While overexpression of PGC-1α increases muscle mitochondrial content and oxidative type I fibres, it does not improve insulin action. Activation of CAMK4 also increases the content of type I muscle fibres, PGC-1α level and mitochondrial content. However, it remains unknown whether CAMK4 activation improves insulin action on glucose metabolism in vivo.

Pigment epithelium-derived factor (PEDF), the protein product of the SERPINF1 gene, has been linked to distinct diseases involving adipose or bone tissue, the metabolic syndrome, and osteogenesis imperfecta (OI) type VI. Since mesenchymal stem cell (MSC) differentiation into adipocytes vs. osteoblasts can be regulated by specific factors, PEDF-directed dependency of murine and human MSCs was assessed. PEDF inhibited adipogenesis and promoted osteoblast differentiation of murine MSCs, osteoblast precursors, and human MSCs. Blockade of adipogenesis by PEDF suppressed peroxisome proliferator-activated receptor- (PPAR), adiponectin, and other adipocyte markers by nearly 90% compared with control-treated cells (P<0.001). Differentiation to osteoblasts by PEDF resulted in a common pathway that involved PPAR suppression (P<0.01). Canonical Wnt--catenin signaling results in a MSC differentiation pattern analogous to that seen with PEDF. Thus, adding PEDF enhanced Wnt--catenin signal transduction in human MSCs, demonstrating a novel Wnt agonist function. In PEDF knockout (KO) mice, total body adiposity was increased by >50% compared with controls, illustrating its systemic role as a negative regulator of adipogenesis. Bones from KO mice demonstrated a reduction in mineral content recapitulating the OI type VI phenotype. These results demonstrate that the human diseases associated with PEDF reflect its ability to modulate MSC differentiation.Gattu, A. K., Swenson, E. S., Iwakiri, Y., Samuel, V. T., Troiano, N., Berry, R., Church, C. D., Rodeheffer, M. S., Carpenter, T. O., Chung, C. Determination of mesenchymal stem cell fate by pigment epithelium-derived factor (PEDF) results in increased adiposity and reduced bone mineral content.

To assess the efficacy and safety of pancreatin (pancrelipase) enteric-coated minimicrospheres (MMS) over a one-year period in patients with pancreatic exocrine insufficiency (PEI) due to chronic pancreatitis (CP).This was a 51-week, open-label extension (OLE) of a one-week, multicenter, double-blind, randomized, placebo-controlled trial in India that enrolled patients ≥18 years of age with confirmed PEI due to CP. Patients received pancreatin (Creon® 40000 MMS™) at a dose of 80,000 Ph. Eur. lipase units with each of three main meals/day and 40,000 with each of up to three snacks/day.Of 61 patients entering the OLE, 48 completed treatment (nine were lost to follow up, two withdrew consent, one discontinued due to adverse event [acute exacerbation of CP], one protocol violation). There were significant improvements from baseline to end of OLE in mean ± SD coefficient of fat absorption (CFA: 22.7 ± 12.2%), coefficient of nitrogen absorption (CNA: 6.5 ± 7.9%), body weight (4.9 ± 4.9 kg), BMI (1.9 ± 1.9 kg/m2), and most nutritional laboratory parameters tested (p ≤ 0.001). Mean daily stool frequency was reduced from 2.8 to 1.6 (p < 0.001). Improvements in clinical symptoms, clinical global impression of disease symptoms, and quality of life were also observed. Treatment-emergent adverse events (TEAEs) were observed in 64% of patients overall. Only 13% of patients experienced TEAEs judged treatment related.In patients with PEI due to CP, treatment with pancreatin for one year was associated with significant improvements in fat absorption, nitrogen absorption, and nutritional parameters, improvements in clinical symptoms, and a favorable safety and tolerability profile.