Jin Zuo

Proteomics-Based Identification of Differentially-Expressed Proteins Including Galectin-1 in the Blood Plasma of Type 2 Diabetic Patients

Type 2 diabetes (T2D) is a very heterogeneous and multifactorial disease. The pathophysiology of T2D is presumed to occur with an alteration in the levels of plasma proteins. To identify these differentially expressed proteins, plasma samples from normal and T2D humans were subjected to two-dimensional gel electrophoresis, quantitative densitometry, and mass spectrometry. Up to 200 protein spots were visible on each gel, of which 57 appeared modulated in diabetic individuals. Subsequently, 31 spots with > or =2-fold change in their expression were analyzed by MALDI-TOF mass spectrometry leading to the identification of 11 proteins with average sequence coverage of approximately 38%. The expression of apolipoprotein A-I was reduced by 4.2-fold, and galectin-1 was increased 4.8 times in diabetic samples. Induction of galectin-1 in T2D samples was confirmed by ELISA. In addition, the dose-dependent treatment of rat L6 skeletal muscle cells with glucose resulted in an upregulation of galectin-1. These data implicate the association of galectin-1 with the pathophysiology of diabetes and identify galectin-1 as a novel diagnostic marker protein in T2D patients.

Protein kinase C-ζ regulation of GLUT4 translocation through actin remodeling in CHO cells

Actin remodeling plays a crucial role in insulin-induced translocation of glucose transporter 4 (GLUT4) from the cytoplasm to the plasma membrane and subsequent glucose transport. Protein kinase C (PKC) ζ has been implicated in this translocation process, although the exact mechanism remains unknown. In this study, we investigated the effect of PKCζ on actin cytoskeleton and translocation of GLUT4 in CHO-K1 cells expressing myc-tagged GLUT4. Insulin stimulated the phosphorylation of PKCζ at Thr410 with no apparent effect on its protein expression. Moreover, insulin promoted colocalization of PKCζ and actin that could be abolished by Latrunculin B. The overexpression of PKCζ mimicked the insulin-induced change in actin cytoskeleton and translocation of GLUT4. These effects were also completely abrogated by Latrunculin B treatment. Using cell-permeable pseudosubstrate (PS) inhibitor of PKCζ, the response to insulin could be alleviated. Our results strongly suggest that PKCζ mediates the stimulatory effect of insulin on GLUT4 translocation through its interaction with actin cytoskeleton.

High glucose upregulates pantothenate kinase 4 (PanK4) and thus affects M2-type pyruvate kinase (Pkm2)

A new Rattus norvegicus PanK gene was isolated by mRNA differential display from high concentration glucose-stimulated rat, which encodes a human PanK4-like protein with KOG2201 and KOG4584 domain. Proteins that interact with rat PanK4 were identified by the application of the yeast two-hybrid system. One of the components, Pkm2, was found to be associated with rat PanK4 and its two domains under both in vitro and in vivo conditions. Immunofluorescence staining and confocal scanning experiments showed that PanK4 could transiently co-express with Pkm2 in the cytoplasm of HeLa cell and HEK293T cell. These findings suggest that PanK4 interacts with Pkm2 and thereby may modulate the glucose metabolism through regulating the activity of Pkm2.

Gene Expression Profile of Human Skeletal Muscle and Adipose Tissue of Chinese Han Patients with Type 2 Diabetes Mellitus

OBJECTIVE To study the differential patterns of gene expression in skeletal muscle and adipose tissue between type 2 diabetes mellitus (T2DM) patients and healthy subjects using DNA microarray analysis. METHODS T2DM patiens were divided into female group, young male group and old male group. DNA microarray analysis and quantitative real-time PCR were carried out to analyze the relation between gene expressions and T2DM. RESULTS The mRNA expression of 298, 578, and 350 genes was changed in the skeletal muscle of diabetes mellitus patients compared with control subjects. The 1320, 1143, and 2847 genes were modified in adipose tissue of the three groups. Among the genes surveyed, the change of 25 and 39 gene transcripts in skeletal muscle and adipose tissue was > or = 2 folds. These differentially expressed genes were classified into 15 categories according to their functions. CONCLUSION New genes are found and T2DM can be prevented or cured.

Cobalt protoporphyrin induces HO-1 expression mediated partially by FOXO1 and reduces mitochondria-derived reactive oxygen species production.

Background Reactive oxygen species arise in the mitochondria as byproducts of respiration and oxidase activity and have important roles in many physiological and pathophysiological conditions. The level of reactive oxygen species is regulated by a number of enzymes and physiological antioxidants, including HO-1, Sod2, catalase and COX-2, etc. And HO-1 against oxidative stress requires an increase in stress-responsive genes, such as Sod2 and catalase. Especially for the activity of HO-1, cobalt protoporphyrin is known to be a potent and effective inducer in many tissues. The transcription factor, FOXO1 is resistant to oxidative stress through downregulating reactive oxygen species production. Previous study showed that FOXO1 induces HO-1 expression by binding to HO-1 promoter. The question whether cobalt protoporphyrin induces HO-1 expression mediated by FOXO1 and subsequently lessens reactive oxygen species production remains to be elucidated. Results Cobalt protoporphyrin enhances the expression of FOXO1 and facilitates FOXO1 binding to HO-1 promoter and increasing its transcriptional activity without influencing the FOXO1 protein stability. CoPP induces HO-1 and other oxidative stress-responsive genes expression, such as catalase, cytochrome c, Sod2, and COX-2, and decreases mitochondria-derived reactive oxygen species production, which are mediated partially by FOXO1. Conclusions Cobalt protoporphyrin induces HO-1 and other oxidative stress-responsive genes expression mediated partially by FOXO1, and has an important role in reducing cellular reactive oxygen species level. Cobalt protoporphyrin may be a more promising therapeutic agent to upregulate some antioxidantive genes.

Pentaspan membrane glycoprotein, prominin-1, is involved in glucose metabolism and cytoskeleton alteration.

This study constitutes the first report revealing the participation of prominin-1 in glucose metabolism and cytoskeleton alteration. Upon stimulation with high glucose, the expression of prominin-1 was up-regulated with concomitant down-regulation of its phosphorylation. Prominin-1 mutated at its phosphorylation site inflicted a global change in the expression of several genes associated with glucose metabolism in L6 myotube cells. Further, the over-expression of prominin-1 promoted glucose uptake in these cells. Prominin-1 undergoes sustained repression of its expression during confluence and differentiation of L6 myotube cells. The expression of prominin-1 in the MDCK cell modulated cell morphology and promoted cellular migration. These data imply that prominin-1 is involved in glucose metabolism and may regulate cellular glucose through its effect on cytoskeleton.

Genetic variations of the CDC2L2 gene are associated with type 2 diabetes in a Han Chinese cohort

The purpose of the present study was to study the potential association of CDC2L2 variations with type 2 diabetes (T2D).

PanK4 inhibits pancreatic β-cell apoptosis by decreasing the transcriptional level of pro-caspase-9

PanK4 inhibits pancreatic β-cell apoptosis by decreasing the transcriptional level of pro-caspase-9