Vaspin Is an Adipokine Ameliorating ER Stress in Obesity as a Ligand for Cell-Surface GRP78/MTJ-1 Complex

It is unknown whether adipokines derived from adipose tissues modulate endoplasmic reticulum (ER) stress induced in obesity. Here, we show that visceral adipose tissue-derived serine protease inhibitor (vaspin) binds to cell-surface 78-kDa glucose-regulated protein (GRP78), which is recruited from ER to plasma membrane under ER stress. Vaspin transgenic mice were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis, while vaspin-deficient mice developed glucose intolerance associated with upregulation of ER stress markers. With tandem affinity tag purification using HepG2 cells, we identified GRP78 as an interacting molecule. The complex formation of vaspin, GRP78, and murine tumor cell DnaJ-like protein 1 (MTJ-1) (DnaJ homolog, subfamily C, member 1) on plasma membrane was confirmed by cell-surface labeling with biotin and immunoprecipitation in liver tissues and H-4-II-E-C3 cells. The addition of recombinant human vaspin in the cultured H-4-II-E-C3 cells also increased the phosphorylation of Akt and AMP-activated protein kinase (AMPK) in a dose-dependent manner, and anti-GRP78 antibodies completely abrogated the vaspin-induced upregulation of pAkt and pAMPK Vaspin is a novel ligand for cell-surface GRP78/MTJ-1 complex, and its subsequent signals exert beneficial effects on ER stress-induced metabolic dysfunctions. Diabetes 61:2823-2832, 201

In Silico Prediction and Analysis of Caenorhabditis EF-hand Containing Proteins

Calcium (Ca+2) is a ubiquitous messenger in eukaryotes including Caenorhabditis. Ca+2-mediated signalling processes are usually carried out through well characterized proteins like calmodulin (CaM) and other Ca+2 binding proteins (CaBP). These proteins interact with different targets and activate it by bringing conformational changes. Majority of the EF-hand proteins in Caenorhabditis contain Ca+2 binding motifs. Here, we have performed homology modelling of CaM-like proteins using the crystal structure of Drosophila melanogaster CaM as a template. Molecular docking was applied to explore the binding mechanism of CaM-like proteins and IQ1 motif which is a ∼25 residues and conform to the consensus sequence (I, L, V)QXXXRXXXX(R,K) to serve as a binding site for different EF hand proteins. We made an attempt to identify all the EF-hand (a helix-loop-helix structure characterized by a 12 residues loop sequence involved in metal coordination) containing proteins and their Ca+2 binding affinity in Caenorhabditis by analysing the complete genome sequence. Docking studies revealed that F165, F169, L29, E33, F44, L57, M61, M96, M97, M108, G65, V115, F93, N104, E144 of CaM-like protein is involved in the interaction with IQ1 motif. A maximum of 170 EF-hand proteins and 39 non-EF-hand proteins with Ca+2/metal binding motif were identified. Diverse proteins including enzyme, transcription, translation and large number of unknown proteins have one or more putative EF-hands. Phylogenetic analysis revealed seven major classes/groups that contain some families of proteins. Various domains that we identified in the EF-hand proteins (uncharacterized) would help in elucidating their functions. It is the first report of its kind where calcium binding loop sequences of EF-hand proteins were analyzed to decipher their calcium affinities. Variation in Ca+2-binding affinity of EF-hand CaBP could be further used to study the behaviour of these proteins. Our analyses postulated that Ca+2 is likely to be key player in Caenorhabditis cell signalling

Urinary angiotensinogen is a marker for tubular injuries in patients with type 2 diabetes

Takahiro Terami,1 Jun Wada,1 Kentaro Inoue,1 Atsuko Nakatsuka,1,2 Daisuke Ogawa,1,2 Sanae Teshigawara,1 Kazutoshi Murakami,1,3 Akihiro Katayama,1 Jun Eguchi,1 Hirofumi Makino11Department of Medicine and Clinical Science, 2Department of Diabetic Nephropathy, 3Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, JapanPurpose: Urinary angiotensinogen has been reported as a marker for the activation of intrarenal renin–angiotensin system (RAS) in various kidney diseases. To investigate the importance of urinary angiotensinogen in diabetic nephropathy, we compared the urinary levels of angiotensinogen, albumin, and α1-microglobulin.Materials and methods: Japanese patients with type 2 diabetes at various stages of nephropathy (n=85) were enrolled, and we measured albumin/creatinine ratio (ACR) and urinary excretion of angiotensinogen and α1-microglobulin. We also compared the clinical data of the patients treated with or without angiotensin II receptor blockers or angiotensin-converting enzyme inhibitors (RAS inhibitors [+], n=51; RAS inhibitors [−], n=34).Results: Urinary angiotensinogen levels positively correlated with ACR (r =0.367, P=3.84×10-4) and urinary α1-microglobulin (r=0.734, P=1.32 × 10-15), while they negatively correlated with estimated glomerular filtration ratio (eGFR) (r=−0.350, P=1.02 × 10-3) and high-density lipoprotein cholesterol (r=−0.216, P=0.049). Multiple regression analysis was carried out to predict urinary angiotensinogen levels by employing eGFR, ACR, and urinary α1-microglobulin as independent variables; only urinary α1-microglobulin entered the regression equation at a significant level. Although ACR was higher in the RAS inhibitors (+) group, urinary α1-microglobulin and angiotensinogen did not show significant increase in the RAS inhibitors (+) group.Conclusion: Urinary angiotensinogen is well correlated with urinary α1-microglobulin and reflected the tubular injuries which may be associated with the intrarenal RAS activation in patients with type 2 diabetes.Keywords: diabetic nephropathy, urinary biomarkers, renin–angiotensin system, angiotensinogen, α1-microglobulin, albumi

Microwell-mediated Control of Embryoid Body Size Regulates Embryonic Stem Cell Fate Via Differential Expression of WNT5a and WNT11

Recently, various approaches for controlling the embryonic stem (ES) cell microenvironment have been developed for regulating cellular fate decisions. It has been reported that the lineage specific differentiation could be affected by the size of ES cell colonies and embryoid bodies (EBs). However, much of the underlying biology has not been well elucidated. In this study, we used microengineered hydrogel microwells to direct ES cell differentiation and determined the role of WNT signaling pathway in directing the differentiation. This was accomplished by forming ES cell aggregates within microwells to form different size EBs. We determined that cardiogenesis was enhanced in larger EBs (450 μm in diameter), and in contrast, endothelial cell differentiation was increased in smaller EBs (150 μm in diameter). Furthermore, we demonstrated that the EB-size mediated differentiation was driven by differential expression of WNTs, particularly noncanonical WNT pathway, according to EB size. The higher expression of WNT5a in smaller EBs enhanced endothelial cell differentiation. In contrast, the increased expression of WNT11 enhanced cardiogenesis. This was further validated by WNT5a-siRNA transfection assay and the addition of recombinant WNT5a. Our data suggest that EB size could be an important parameter in ES cell fate specification via differential gene expression of members of the noncanonical WNT pathway. Given the size-dependent response of EBs to differentiate to endothelial and cardiac lineages, hydrogel microwell arrays could be useful for directing stem cell fates and studying ES cell differentiation in a controlled manner.National Institutes of Health (U.S.) (DE019024, HL092836, and EB007249