Calpain 3 gene expression in skeletal muscle is associated with body fat content and measures of insulin resistance

OBJECTIVE: To investigate whether skeletal muscle gene expression of calpain 3 is related to obesity and insulin resistance.

DESIGN: Cross-sectional studies in 27 non-diabetic human subjects and in Psammomys obesus, a polygenic animal model of obesity and type 2 diabetes.

MEASUREMENTS: Expression of CAPN3 in skeletal muscle was measured using Taqman fluorogenic PCR. In the human subjects, body composition was assessed by DEXA and insulin sensitivity was measured by euglycemic-hyperinsulinemic clamp. In Psammomys obesus, body composition was determined by carcass analysis, and substrate oxidation rates, physical activity and energy expenditure were measured by whole-body indirect calorimetry.

RESULTS: In human subjects, calpain 3 gene expression was negatively correlated with total (P=0.022) and central abdominal fat mass (P=0.034), and with blood glucose concentration in non-obese subjects (P=0.017). In Psammomys obesus, calpain 3 gene expression was negatively correlated with circulating glucose (P=0.013) and insulin (P=0.034), and with body fat mass (P=0.049). Indirect calorimetry revealed associations between calpain 3 gene expression and carbohydrate oxidation (P=0.009) and energy expenditure (P=0.013).

CONCLUSION/INTERPRETATION: Lower levels of expression of calpain 3 in skeletal muscle were associated with reduced carbohydrate oxidation and elevated circulating glucose and insulin concentrations, and also with increased body fat and in particular abdominal fat. Therefore, reduced expression of calpain 3 in both humans and Psammomys obesus was associated with phenotypes related to obesity and insulin resistance.

New approaches to gene discovery with animal models of obesity and diabetes

DNA-based approaches to the discovery of genes contributing to the development of type 2 diabetes have not been very successful despite substantial investments of time and money. The multiple gene-gene and gene-environment interactions that influence the development of type 2 diabetes mean that DNA approaches are not the ideal tool for defining the etiology of this complex disease. Gene expression-based technologies may prove to be a more rewarding strategy to identify diabetes candidate genes. There are a number of RNA-based technologies available to identify genes that are differentially expressed in various tissues in type 2 diabetes. These include differential display polymerase chain reaction (ddPCR), suppression subtractive hybridization (SSH), and cDNA microarrays. The power of new technologies to detect differential gene expression is ideally suited to studies utilizing appropriate animal models of human disease. We have shown that the gene expression approach, in combination with an excellent animal model such as the Israeli sand rat (Psammomys obesus), can provide novel genes and pathways that may be important in the disease process and provide novel therapeutic approaches. This paper will describe a new gene discovery, beacon, a novel gene linked with energy intake. As the functional characterization of novel genes discovered in our laboratory using this approach continues, it is anticipated that we will soon be able to compile a definitive list of genes that are important in the development of obesity and type 2 diabetes.

A custom-built insulin resistance gene chip

Objectives/Aim—Microarray (gene chip) technology offers a powerful new tool for analyzing the expression of large numbers of genes in many experimental samples. The aim of this study was to design, construct, and use a gene chip to measure the expression levels of key genes in metabolic pathways related to insulin resistance.
Methods—We selected genes that were implicated in the development of insulin resistance, including genes involved in insulin signaling; glucose uptake, oxidation, and storage; fat uptake, oxidation, and storage; cytoskeletal components; and transcription factors. The key regulatory genes in the pathways were identified, along with other recently identified candidate genes such as calpain-10. A total of 242 selected genes (including 32 internal control elements) were sequence-verified, purified, and arrayed on aldehyde-coated slides.
Results—Where more than 1 clone containing the gene of interest was available, we chose those containing the genes in the 5' orientation and an insert size of around 1.5 kb. Of the 262 clones purchased, 56 (21%) were found to contain sequences other than those expected. In addition, 2 (1%) did not grow under standard conditions and were assumed to be nonviable. In these cases, alternate clones containing the gene of interest were chosen as described above. The current version of the Insulin Resistance Gene Chip contains 210 genes of interest, plus 48 control elements. A full list of the genes is available at http://www.hbs.deakin.edu.au/mru/research/gene_chip_tech/genechip_three.htm/.
Conclusions—The human Insulin Resistance Gene Chip that we have constructed will be a very useful tool for investigating variation in the expression of genes relevant to insulin resistance under various experimental conditions. Initially, the gene chip will be used in studies such as exercise interventions, fasting, euglycemic-hyperinsulinemic clamps, and administration of antidiabetic agents

The use of correspondence analysis to develop a scale to measure workplace morale from multi-level data

This paper focuses on the issue of comparing social groups or collectivities using measures derived from individual-level multivariate data. In this case, groups need to be differentiated such that: (a) between-group differences are maximized; (b) within-group differences are minimised; and (c) `differences' are calibrated to a scale that reflects a set indicators or observed variables.This paper demonstrates empirically how correspondence analysis can achieve this. It presents a scale of `workplace morale' derived from the responses of employees in a large sample of workplaces to questions concerning satisfaction with various facets of their job and their workplace. The scale derived through correspondence analysis is shown to achieve the three criteria described above.

Obesity and diabetes gene discovery approaches

New treatments are currently required for the common metabolic diseases obesity and type 2 diabetes. The identification of physiological and  biochemical factors that underlie the metabolic disturbances observed in obesity and type 2 diabetes is a key step in developing better therapeutic outcomes. The discovery of new genes and pathways involved in the  pathogenesis of these diseases is critical to this process, however  identification of genes that contribute to the risk of developing these diseases represents a significant challenge as obesity and type 2 diabetes are complex diseases with many genetic and environmental causes. A number of diverse approaches have been used to discover and validate potential new targets for obesity and diabetes. To date, DNA-based approaches using candidate gene and genome-wide linkage analysis have had limited success in identifying genomic regions or genes involved in the development of these diseases. Recent advances in the ability to evaluate linkage analysis data from large family pedigrees using variance components based linkage analysis show great promise in robustly identifying genomic regions associated with the development of obesity and diabetes. RNA-based technologies such as cDNA microarrays have identified many genes differentially expressed in tissues of healthy and diseased subjects. Using a combined approach, we are endeavouring to focus attention on differentially expressed genes located in chromosomal regions previously linked with obesity and / or diabetes. Using this strategy, we have identified Beacon as a potential new target for obesity and diabetes.

Elevation in tanis expression alters glucose metabolism and insulin sensitivity in H4IIE cells

Increased hepatic glucose output and decreased glucose utilization are implicated in the development of type 2 diabetes. We previously reported that the expression of a novel gene, Tanis, was upregulated in the liver during fasting in the obese/diabetic animal model Psammomys obesus. Here, we have further studied the protein and its function. Cell fractionation indicated that Tanis was localized in the plasma membrane and microsomes but not in the nucleus, mitochondria, or soluble protein fraction. Consistent with previous gene expression data, hepatic Tanis protein levels increased more significantly in diabetic P. obesus than in nondiabetic controls after fasting. We used a recombinant adenovirus to increase Tanis expression in hepatoma H4IIE cells and investigated its role in metabolism. Tanis overexpression reduced glucose uptake, basal and insulin-stimulated glycogen synthesis, and glycogen content and attenuated the suppression of PEPCK gene expression by insulin, but it did not affect insulin-stimulated insulin receptor phosphorylation or triglyceride synthesis. These results suggest that Tanis may be involved in the regulation of glucose metabolism, and increased expression of Tanis could contribute to insulin resistance in the liver.

Teaching organisational theory in undergraduate management programmes: an exercise in facilitated theory testing for active experimentation

This paper argues that there is an opportunity to improve the way that social science theory is taught by introducing an exercise in facilitated theory testing through active experimentation. This paper describes a learning experience that enables students to discover the dynamic nature of theoretical discoveries. This idea is grounded in the notion that students will gain much from learning about and testing theory experientially using real world data. A data based exercise is outlined and illustrated to reveal a learning experience that provides an opportunity to improve the way social science is taught by linking theory to empirical data. We argue that this provides an opportunity to offer a more holistic learning experience for theory teaching. The paper will be of special interest to those teaching theory in management, commerce, business and organisational studies courses. It will also be of interest to a more general audience because it provides a framework that can be modified whenever forging a connection between theory and 'the real world' is a primary learning objective.

Experiential learning in social science theory: an investigation of the relationship between student enjoyment and learning

This paper provides an analysis of student experiences of an approach to teaching theory that integrates the teaching of theory and data analysis. The argument that supports this approach is that theory is most effectively taught by using empirical data in order to generate and test propositions and hypotheses, thereby emphasising the dialectic relationship between theory and data through experiential learning. Bachelor of Commerce students in two second-year substantive organisational theory subjects were introduced to this method of learning at a large, multi-campus Australian university. In this paper, we present a model that posits a relationship between students' perceptions of their learning, the enjoyment of the experience and expected future outcomes. The results of our evaluation reveal that a majority of students:

•enjoyed this way of learning;
•believed that the exercise assisted their learning of substantive theory, computing applications and the nature of survey data; and
•felt that what they have learned could be applied elsewhere.

We argue that this approach presents the potential to improve the way theory is taught by integrating theory, theory testing and theory development; moving away from teaching theory and analysis in discrete subjects; and, introducing iterative experiences in substantive subjects.

Beacon interacts with cdc2/cdc28-like kinases

Previously we found elevated beacon gene expression in the hypothalamus of obese Psammomys obesus. Beacon administration into the lateral ventricle of P. obesus stimulated food intake and body weight gain. In the current study we used yeast two-hybrid technology to screen for proteins in the human brain that interact with beacon. CLK4, an isoform of cdc2/cdc28-like kinase family of proteins, was identified as a strong interacting partner for beacon. Using active recombinant proteins and a surface plasmon resonance based detection technique, we demonstrated that the three members of this subfamily of kinases (CLK1, 2, and 4) all interact with beacon. Based on the known sequence and functional properties of beacon and CLKs, we speculate that beacon could either modulate the function of key regulatory molecules such as PTP1B or control the expression patterns of specific genes involved in the central regulation of energy metabolism.

The effects of technical and social conditions on workplace trust

This paper investigates the extent to which the technical and social contexts of organizations independently affect levels of workplace trust. We argue that, in an organizational context, trust is not just a relationship between an individual subject (the truster) and an object (the trustee) but is subject to effects from the conditions of the work relationship itself. We describe the organizational context as comprising both a technical system of production (where work gets done through the specification of tasks) and a social system of work (where problems of effort, compliance, conformity and motivation are managed). We analyse the relationship between trust and these two aspects of workplace context (technical and social systems). We also operationalize this in terms of differences between industries,  occupational composition and human resource management practices. The model is tested using data drawn from the 1995 Australian Workplace Industrial Relations Survey. The results confirm that differences in industry, occupational composition and HRM practices all impact on levels of workplace trust. We review these results in terms of their implications for future research into the problem of analysing variation in trust at both the workplace and individual levels.

Reporting and the politics of difference : (non) disclosure on ethnic minorities

This article is based on two related research questions. First, what is the level of disclosure on ethnic minorities in the two sectors of the U.K. economy that historically have employed the most ethnic minorities: the banking and retail sectors? And secondly, what influences the (non)disclosure? It specifically investigates the level of disclosures from 1935 to 1998 and situates them within the changing social, political and economic context of this period. It is contended that the changing pattern of disclosure during this period can be understood with reference to changes in the political strategies for managing the threat of racism adopted by successive governments. The article provides some tentative theoretical reflections on the nature of the racism problematic and the way in which power may be seen to operate through (non)disclosure in this particular instance.

Identification and characterization of a lymphocytic Rho-GTPase effector: rhotekin-2

Rhotekin belongs to the group of proteins containing a Rho-binding domain that are target peptides (effectors) for the Rho-GTPases. We previously identified a novel cDNA with homology to human rhotekin and in this study we cloned and characterized the coding region of this novel 12-exon gene. The ORF encodes a 609 amino-acid protein comprising a Class I Rho-binding domain and pleckstrin homology (PH) domain. Cellular cDNA expression of this new protein, designated Rhotekin-2 (RTKN2), was shown in the cytosol and nucleus of CHO cells. Using bioinformatics and RTPCR we identified three major splice variants, which vary in both the Rho-binding and PH domains. Real-time PCR studies showed exclusive RTKN2 expression in pooled lymphocytes and further purification indicated sole expression in CD4^_pos T-cells and bone marrow-derived B-cells. Gene expression was increased in quiescent T-cells but negligible in activated proliferating cells. In malignant samples expression was absent in myeloid leukaemias, low in most B-cell malignancies and CD8^pos T-cell malignancies, but very high in CD4^pos/CD8^pos T-lymphoblastic lymphoma. As the Rho family is critical in lymphocyte development and function, RTKN2 may play an important role in lymphopoiesis.