No abstract available.
GRB2 Adaptor Protein*

BACKGROUND: Arteriosclerosis obliterans (ASO) is a major cause of adult limb loss worldwide. Autophagy of vascular endothelial cell (VEC) contributes to the ASO progression. However, the molecular mechanism that controls VEC autophagy remains unclear. In this study, we aimed to explore the role of the GRB2 associated binding protein 1 (GAB1) in regulating VEC autophagy. METHODS: In vivo and in vitro studies were applied to determine the loss of adapt protein GAB1 in association with ASO progression. Histological GAB1 expression was measured in sclerotic vascular intima and normal vascular intima. Gain- and loss-of-function of GAB1 were applied in VEC to determine the effect and potential downstream signaling of GAB1. RESULTS: The autophagy repressor p62 was significantly downregulated in ASO intima as compared to that in healthy donor (0.80 vs. 0.20, t = 6.43, P < 0.05). The expression level of GAB1 mRNA (1.00 vs. 0.24, t = 7.41, P < 0.05) and protein (0.72 vs. 0.21, t = 5.97, P < 0.05) was significantly decreased in ASO group as compared with the control group. Loss of GAB1 led to a remarkable decrease in LC3II (1.19 vs. 0.68, t = 5.99, P < 0.05), whereas overexpression of GAB1 significantly led to a decrease in LC3II level (0.41 vs. 0.93, t = 7.12, P < 0.05). Phosphorylation levels of JNK and p38 were significantly associated with gain- and loss-of-function of GAB1 protein. CONCLUSION Loss of GAB1 promotes VEC autophagy which is associated with ASO. GAB1 and its downstream signaling might be potential therapeutic targets for ASO treatment.
Adaptor Proteins, Signal Transducing ; Adult ; Arteriosclerosis Obliterans/genetics* ; Autophagy ; GRB2 Adaptor Protein ; Humans ; Phosphoproteins/metabolism* ; Phosphorylation ; Protein Binding ; Signal Transduction

AIMTo investigate whether free fatty acid impair insulin signaling proteins to inhibit insulin action in rat islet cells.

METHODSAfter rat islet cells were incubated with palmitate (0.25 mmol/L) or oleate (0.125 mmol/L) for 12 hours, 24 hours and 36 hours, western bolt was used to assess the protein abundance of cPKCalpha, Grb2 and FERK2.

RESULTSThe protein content of cPKCalpha were significantly upregulated and the protein abundance of Grb2 and ERK2 was decreased comparing with control in rat islet cells after incubated with free fatty acids.

CONCLUSIONSFree fatty acids may inhibit insulin activity in rat islet cells through up-regulating the expression of cPKCalpha or down-regulating the expression of Grb2 and ERK2.

Animals ; Cells, Cultured ; Fatty Acids, Nonesterified ; blood ; GRB2 Adaptor Protein ; metabolism ; Insulin ; metabolism ; Islets of Langerhans ; metabolism ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Protein Kinase C-alpha ; metabolism ; Rats ; Rats, Sprague-Dawley ; Signal Transduction

AIMTo compare the effects of the non-mitogenetic human acidic fibroblast growth factor (nmhaFGF) and the human acidic fibroblast growth factor (haFGF) on the proliferation and MAPK signal transduction pathway of the malignant tumor cell and to study the clinical safety of nmhaFGF.

METHODSThe mammary tumor cells (MCF-7) were treated with haFGF and nmhaFGF separately. The mitogenic activities of both haFGF and nmhaFGF were detected by MTT method and the cell cycle was analyzed by flow cytometer (FCM). The expression levels of the signal proteins, Grb2 (growth factor receptor bound 2) and ERK1/2 (extracellular signal-regulated kinase 1/2), were detected by semi-quantitative Western blotting method.

RESULTSThe mitogenic activity of nmhaFGF was obviously lower than that of haFGF. The activity of nmhaFGF was weaker than that of the haFGF. The ratio of G1/G0, G2/M of haFGF was markedly lower than that of nmhaFGF and control group, and was reverse in S phase. The expression levels of both Grb2 and ERK1/2 of the nmhaFGF treated group were lower than that of the haFGF treated group and approaching the control group.

CONCLUSIONThe mitogenic activity of the nmhaFGF decreased remarkably. Its mechanism probably via down-regulation of the expression of the signal moleculars, MAPK-ERK1/2 and Grb2.

Breast Neoplasms ; metabolism ; pathology ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Down-Regulation ; Female ; Fibroblast Growth Factor 1 ; genetics ; pharmacology ; GRB2 Adaptor Protein ; metabolism ; Humans ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Mitosis ; drug effects ; Mutation