Sajan M.P.,Medical and Research Services |
Farese R.V.,Medical and Research Services |
Farese R.V.,Roskamp Institute |
Farese R.V.,University of South Florida
Diabetologia | Year: 2012
Aims/hypothesis We examined the role of protein kinase C-ι (PKC-ι) in mediating alterations in the abundance of enzymes in hepatocytes of type 2 diabetic humans that contribute importantly to the development of lipid and carbohydrate abnormalities in type 2 diabetes. Methods We examined (1) insulin signalling in isolated hepatocytes of non-diabetic and type 2 diabetic humans and (2) the effects of two newly developed small molecule PKC-ι inhibitors on aberrant signalling and downstream processes. Results In contrast with PKC-ι deficiency in diabetic muscle, which diminishes glucose transport, PKC-ι in diabetic hepatocytes was overproduced and overactive, basally and after insulin treatment, and, moreover, was accompanied by increased abundance of PKC-ι-dependent lipogenic, proinflammatory and gluconeogenic enzymes. Heightened PKC-ι activity most likely reflected heightened activity of IRS-2-dependent phosphatidylinositol 3-kinase (PI3K), as IRS-1 levels and IRS-1/PI3K activity were markedly diminished. Importantly, insulin-stimulated PKC-ι abundance and its overabundance in diabetic hepatocytes was reversed in vitro by both insulin deprivation and PKC-ι inhibitors; this suggested operation of an insulin-driven, feed-forward/ positive-feedback mechanism. In contrast with PKC-ι, protein kinase B (Akt2) activity and activation by insulin was diminished, apparently reflecting IRS-1 deficiency. Treatment of diabetic hepatocytes with PKC-ι/λ inhibitors diminished abundance of lipogenic, proinflammatory and gluconeogenic enzymes. Conclusions/interpretation Our findings suggest that a vicious cycle of PKC-ι overactivity and overproduction exists in hepatocytes of humans with type 2 diabetes and contributes importantly to maintaining overactivity of lipogenic, proinflammatory and gluconeogenic pathways, which underlies the lipid and carbohydrate abnormalities in type 2 diabetes.© 2012 Springer-Verlag (outside the USA).
Sheinerman K.S.,Diamir, Llc |
Tsivinsky V.G.,Diamir, Llc |
Abdullah L.,Roskamp Institute |
Crawford F.,Roskamp Institute |
Umansky S.R.,Diamir, Llc
Aging | Year: 2013
A minimally invasive test for early detection and monitoring of Alzheimer's and other neurodegenerative diseases is a highly unmet need for drug development and planning of patient care. Mild Cognitive Impairment (MCI) is a syndrome characteristic of early stages of many neurodegenerative diseases. Recently, we have identified two sets of circulating brain-enriched miRNAs, the miR-132 family (miR-128, miR-132, miR-874) normalized per miR-491-5p and the miR-134 family (miR-134, miR-323-3p, miR-382) normalized per miR-370, capable of differentiating MCI from age-matched control (AMC) with high accuracy. Here we report a biomarker validation study of the identified miRNA pairs using larger independent sets of age- and gender- matched plasma samples. The biomarker pairs detected MCI with sensitivity, specificity and overall accuracy similar to those obtained in the first study. The miR-132 family biomarkers differentiated MCI from AMC with 84%-94% sensitivity and 96%-98% specificity, and the miR-134 family biomarkers demonstrated 74%- 88% sensitivity and 80-92% specificity. When miRNAs of the same family were combined, miR-132 and miR-134 family biomarkers demonstrated 96% and 87% overall accuracy, respectively. No statistically significant differences in the biomarker concentrations in samples obtained from male and female subjects were observed for either MCI or AMC. The present study also demonstrated that the highest sensitivity and specificity are achieved with pairs of miRNAs whose concentrations in plasma are highly correlated. © Sheinerman et al.
Cui J.,Roskamp Institute |
Shen Y.,Roskamp Institute |
Li R.,Roskamp Institute
Trends in Molecular Medicine | Year: 2013
Estrogens are the primary female sex hormones and play important roles in both reproductive and non-reproductive systems. Estrogens can be synthesized in non-reproductive tissues such as liver, heart, muscle, bone and brain, and tissue-specific estrogen synthesis is consistent with a diversity of estrogen actions. In this article we review tissue and cell-specific estrogen synthesis and estrogen receptor signaling in three parts: (i) synthesis and metabolism, (ii) the distribution of estrogen receptors and signaling, and (iii) estrogen functions and related disorders, including cardiovascular diseases, osteoporosis, Alzheimer's disease (AD), and Parkinson disease (PD). This comprehensive review provides new insights into estrogens by giving a better understanding of the tissue-specific estrogen effects and their roles in various diseases. © 2012 Elsevier Ltd.
Ojo J.-O.,Roskamp Institute |
Mouzon B.,Roskamp Institute |
Greenberg M.B.,Roskamp Institute |
Bachmeier C.,Roskamp Institute |
And 2 more authors.
Journal of Neuropathology and Experimental Neurology | Year: 2013
Extensive tau-immunoreactive neurons and glial cells associated with chronic traumatic encephalopathy (CTE) have been documented in the brains of some professional athletes and others with a history of repetitive mild traumatic brain injury (r-mTBI). The neuropathology and tau involvement in mTBI have not been extensively studied in animal models, particularly in aged animals. We investigated the effects of single mTBI (s-mTBI) and r-mTBI in 18-month-old hTau mice, which express wild-type human tau isoforms on a null murine tau background (n = 3-5 per group). At this age, hTau mice already demonstrate tau pathology, but there was a significant increase in phospho-tau immunoreactivity in response to r-mTBI, but not to s-mTBI,as determined using multiple phospho-tau-specific antibodies. Repetitive mTBI also resulted in a marked increase in astrocyte/microglia activation notably in the superficial layer of the motor/somatosensory cortex and the corpus callosum. We did not observe the perivascular tau pathology, neuritic threads, or astrocytic tangles that are commonly found in human CTE. The increase in phospho-tau in the r-mTBI mice suggests that this may be a useful model for investigating further the link between mTBI, particularly r-mTBI, and tau pathobiology in CTE and in understanding responses of the aged brain to mTBI. © 2013 by the American Association of Neuropathologists, Inc.
Li R.,Roskamp Institute |
Singh M.,University of North Texas Health Science Center
Frontiers in Neuroendocrinology | Year: 2014
Studies have shown differences in specific cognitive ability domains and risk of Alzheimer's disease between the men and women at later age. However it is important to know that sex differences in cognitive function during adulthood may have their basis in both organizational effects, i.e., occurring as early as during the neuronal development period, as well as in activational effects, where the influence of the sex steroids influence brain function in adulthood. Further, the rate of cognitive decline with aging is also different between the sexes. Understanding the biology of sex differences in cognitive function will not only provide insight into Alzheimer's disease prevention, but also is integral to the development of personalized, gender-specific medicine. This review draws on epidemiological, translational, clinical, and basic science studies to assess the impact of sex differences in cognitive function from young to old, and examines the effects of sex hormone treatments on Alzheimer's disease in men and women. © 2014 Elsevier Inc.
Farese R.V.,University of South Florida |
Sajan M.P.,Roskamp Institute
American Journal of Physiology - Endocrinology and Metabolism | Year: 2010
Atypical protein kinase C (aPKC) isoforms mediate insulin effects on glucose transport in muscle and adipose tissues and lipid synthesis in liver and support other metabolic processes, expression of enzymes needed for islet insulin secretion and hepatic glucose production/release, CNS appetite suppression, and inflammatory responses. In muscle, selective aPKC deficiency impairs glucose uptake and produces insulin resistance and hyperinsulinemia, which, by activating hepatic aPKC, provokes inordinate increases in lipid synthesis and produces typical "metabolic syndrome" features. In contrast, hepatic aPKC deficiency diminishes lipid synthesis and protects against metabolic syndrome features. Unfortunately, aPKC is deficient in muscle but paradoxically conserved in liver in obesity and type 2 diabetes mellitus; this combination is particularly problematic because it promotes lipid and carbohydrate abnormalities. Accordingly, metabolic effects of aPKCs can be "good" or "bad," depending upon nutritional status; thus, muscle glucose uptake, islet insulin secretion, hepatic glucose and lipid production/release, and adipose fat synthesis/ storage would be important for survival during periods of limited food availability and therefore be "good." However, during times of food surfeit, excessive activation of hepatic aPKC, whether caused by overnutrition or impairments in extrahepatic effects of insulin, would lead to inordinate increases in hepatic lipid synthesis and metabolic syndrome features and therefore be "bad." In keeping with these ideas, the inhibition of hepatic aPKC markedly ameliorates lipid and carbohydrate abnormalities in experimental models of obesity and type 2 diabetes. We postulate that a similar approach may be useful for treating humans.
Li R.,Roskamp Institute |
Shen Y.,Roskamp Institute
Life Sciences | Year: 2013
The study of specific target protein expression is often performed by western blotting, a commonly used method to measure the protein expression in neuroscience research by specific antibodies. Housekeeping proteins are used as an internal control for protein loading as well as reference in the western blotting analysis. This practice is based on the belief that such housekeeping genes are considered to be ubiquitously and constitutively expressed in every tissue and produce the minimal essential transcripts necessary for normal cellular function. The most commonly used housekeeping proteins are β-actin, β-tubulin, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). However, recent studies have shown significant variation in some housekeeping genes both at the mRNA and protein levels in various neuropathological events, such as spinal cord injury and Alzheimer's diseases. Changes of housekeeping genes are also induced by non-neuronal diseases in various tissues. Therefore, these discoveries raise a potential concern regarding whether using a housekeeping protein as an internal standard for target protein analysis is an appropriate practice. This minireview will focus on (I) the effects of neuronal and non-neuronal diseases, experimental condition, and tissue-specific roles on alteration of housekeeping genes, and (II) alternative internal standards for gene and protein expression analysis. © 2013 Elsevier Inc.
Laco G.S.,Roskamp Institute
Biochimie | Year: 2015
A key target in the treatment of HIV-1/AIDS has been the viral protease. Here we first studied in silico the evolution of protease resistance. Primary active site resistance mutations were found to weaken interactions between protease and both inhibitor and substrate P4-P4′ residues. We next studied the effects of secondary resistance mutations, often distant from the active site, on protease binding to inhibitors and substrates. Those secondary mutations contributed to the rise of multi-drug resistance while also enhancing viral replicative capacity. Here many secondary resistance mutations were found in the HIV-1 protease substrate-grooves, one on each face of the symmetrical protease dimer. The protease active site binds substrate P4-P4′ residues, while the substrate-groove allows the protease to bind residues P12-P5/P5′-P12′, for a total of twenty-four residues. The substrate-groove secondary resistance mutations were found to compensate for the loss of interactions between the inhibitor resistant protease active site and substrate P4-P4′ residues, due to primary resistance mutations, by increasing interactions with substrate P12-P5/P5′-P12′ residues. In vitro experiments demonstrated that a multi-drug resistant protease with substrate-groove resistance mutations was slower than wild-type protease in cleaving a peptide substrate, which did not allow for substrate-groove interactions, while it had similar activity as wild-type protease when using a Gag polyprotein in which cleavage-site P12-P5/P5′-P12′ residues could be bound by the protease substrate-grooves. When the Gag MA/CA cleavage site P12-P5/P5′-P12′ residues were mutated the multi-drug resistant protease cleaved the mutant Gag significantly slower, indicating the importance of the protease S-grooves in binding to substrate. © 2015 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). Al1 rights reserved.
Li R.,Roskamp Institute |
Cui J.,Roskamp Institute |
Shen Y.,Roskamp Institute
Molecular and Cellular Endocrinology | Year: 2014
Estrogens can be synthesized in non-reproductive tissues such as liver, heart, muscle, bone and the brain. During the past decade, increasing evidence suggests that brain estrogen can not only be synthesized by neurons, but also by astrocytes. Brain estrogen also works locally at the site of synthesis in paracrine and/or intracrine fashion to maintain important tissue-specific functions. Here, we will focus on the biology of brain estrogen and its impact on cognitive function and Alzheimer's disease. This comprehensive review provides new insights into brain estrogens by presenting a better understanding of the tissue-specific estrogen effects and their roles in healthy ageing and cognitive function. © 2014 Elsevier Ireland Ltd.
Li R.,Roskamp Institute
Journal of Sport and Health Science | Year: 2014
The differences of learning and memory between males and females have been well documented and confirmed by both human and animal studies. The sex differences in cognition started from early stage of neuronal development and last through entire lifespan. The major biological basis of the gender-dependent cognitive activity includes two major components: sex hormone and sex-related characteristics, such as sex-determining region of the Y chromosome (SRY) protein. However, the knowledge of how much biology of sex contributes to normal cognitive function and elite athletes in various sports are still pretty limited. In this review, we will be focusing on sex differences in spatial learning and memory - especially the role of male- and female-type cognitive behaviors in sports. © 2014 Shanghai University of Sport.