Isolation and characterization of insulin from the Brockmann body of Dissostichus mawsoni, an Antarctic teleost fish

Tissue-Specific Modulation of Gluco- and Growth-Regulatory Factor Abundance by Nesfatin-1 and Nesfatin-1-like Peptide in Goldfish

Nesfatin-1 and nesfatin-1-like peptide (Nlp) are derived from precursors nucleobindin-2 and -1, two calcium and DNA binding proteins, respectively. Both peptides exhibit hormone-like actions in mammals and fish. These functions include insulinotropic effects of nesfatin-1 and Nlp seen in mice and their growth hormone suppressive actions reported in goldfish. We hypothesized that nesfatin-1 and Nlp are insulin stimulatory (in adipose tissue) and modulate growth hormone and insulin-like growth factors and glucose transporters in goldfish. To test this, goldfish were intraperitoneally injected with either nesfatin-1 or Nlp (50 ng/g BW) or saline alone (control) and sampled at one-hour post-injection (in vivo study). In a separate study, tissue samples were collected and were incubated with either nesfatin-1 or Nlp for one or six hours (in vitro study). Transcript (mRNA) abundance data from the adipose tissue suggest that both nesfatin-1 and Nlp significantly upregulate the abundance of preproinsulin, insulin receptors, and pcsk1 and pcsk2 mRNAs. Meanwhile, the abundance of preproglucagon mRNA in the adipose tissue was significantly downregulated in both in vivo and in vitro studies. These results agree with the insulinotropic and glucagonostatic roles for nesfatin-1 and Nlp reported in rodents. The transcript abundance of growth regulators (igf1, igf2a, and ghra) and glucose transporters (slc2a2 and slc5a1) were upregulated in the muscle, while an opposite effect on these mRNAs was found in the liver of goldfish following nesfatin-1 and Nlp administration. Our results suggest that both nesfatin-1 and Nlp have tissue-specific regulatory roles on growth and glucoregulatory elements in the liver and muscle of goldfish. This agrees with our previous studies that showed a suppressive action of nesfatin-1 on growth hormone in goldfish liver. The results presented here provide strong supportive/confirmatory evidence for tissue-specific insulinotropic and gluco- and growth-regulatory actions of nesfatin-1 and Nlp in goldfish.

Goldfish adipocytes are pancreatic beta cell-like, glucose-responsive insulin-producing cells

Glucose homeostasis plays a key role in maintaining stable physiological conditions, and its dysfunction causes severe chronic health issues including diabetes. In this study, we have characterized goldfish adipocytes as cells with properties similar to that of pancreatic β-cells: they express considerable high levels of preproinsulin mRNAs, possess the necessary machinery for processing preproinsulin (prohormone convertases 1 and 2, carboxypeptidase E and trypsin) and responding to extracellular glucose (glucokinase and the glucose transporters 1, 2, and 4), produce insulin in a glucose-responsive manner and express key transcription factors typically involved in pancreas development (Pdx1, Neurogenin3, Nkx2.2, Pax6, and FOXO1A). These findings reinforce the feature of fish adipocytes as alternate sources of active insulin, holding the promise that they could eventually be developed as transplantable sources of this vital hormone.

Biochemical Characterization of Medaka (Oryzias latipes) Transglutaminases, OlTGK1 and OlTGK2, as Orthologues of Human Keratinocyte-Type Transglutaminase

Calcium-dependent transglutaminases (TGs) are a family of enzymes that catalyze protein cross-linking and/or attachment of primary amines in a variety of organisms. Mammalian TGs are implicated in multiple biological events such as skin formation, blood coagulation, and extracellular matrix stabilization. Medaka (Oryzias latipes) has been used as a model fish to investigate the physiological functions of mammalian proteins. By analysis of the medaka genome, we found seven TGs orthologues, some of which apparently corresponded to the mammalian TG isozymes, TG1, TG2, and Factor XIII. All orthologues had preserved amino acid residues essential for enzymatic activity in their deduced primary structures. In this study, we analyzed biochemical properties of two orthologues (OlTGK1 and OlTGK2) of mammalian epithelium-specific TG (TG1) that are significantly expressed at the transcriptional level. Using purified recombinant proteins for OlTGK1 and OlTGK2, we characterized their catalytic reactions. Furthermore, immunohistochemical analyses of fish sections revealed higher expression in the pancreas (OTGK1), intervertebral disk (OlTGK2) and pharyngeal teeth (OlTGK2) as well as in the skin epidermis.

Changes in transcriptional output of human peripheral blood mononuclear cells following resistance exercise

Various types of exercise alter the population of circulating peripheral blood mononuclear cells (PBMCs) and change their transcriptional output. This work examines changes in PBMC populations and transcription in response to resistance exercise training (RET), and identify key transcriptional changes in PBMCs that may play a role in altering peripheral tissues in response to RET. Ten resistance-trained men (20-24 years), performed an acute bout of RET for ~30 min following a 12 h fast. Venous blood was sampled at rest, immediately following exercise, and at 2 h post-exercise and analyzed for total and differential leukocytes and global gene expression using Affymetrix Genechips. Results showed elevated leukocytes, monocytes, lymphocytes, and lactate values immediately post-exercise (P < 0.05) over baseline. At 2 h post-exercise, leukocytes, and granulocytes remained elevated (P < 0.05), whereas lymphocytes were lower than (P < 0.05) baseline values. Initial microarray results showed the greatest transcriptional changes in pathways related to immune response, inflammation, and cellular communication. The change in PBMC population (2 h time point) correlated with a dramatic decrease in the expression of CD160, and XCL1, markers of lymphocyte populations. At the 2 h recovery time point upregulation of matrix metalloproteinase 9, orosomucoid 1, dishevelled-associated activator of morphogenesis 2, and arginase 1 suggest an induction in muscle damage and repair during this time frame. These results demonstrate that an acute bout of RET disrupts cellular homeostasis, induces a transient redistribution of certain leukocytes, and results in transcriptional changes in PBMCs translating into systemic changes in response to RET.