Protein Tyrosine Phosphatase 1B is Impaired in Skeletal Muscle of Diabetic Psammomys Obesus |
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Authors: | Yukio Ikeda Ehud Ziv Eleazar Shafrir Luitgard Mosthaf-Seedorf |
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Institution: | 1. Department of Molecular Signaling, Hagedorn Research Institute, Gentofte, Denmark.;2. Department of Biochemistry and Diabetes Research Unit, Hadassah University Hospital, Jerusalem, 91120, Israel, |
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Abstract: | Protein tyrosine phosphatases (PTPases) have been suggested
to modulate the insulin receptor signal transduction pathways.We
studied PTPases in Psammomys obesus, an animal model of nutritionally
induced insulin resistance. No changes in the protein
expression level of src homology PTPase 2 (SHP-2) (muscle, liver)
or leukocyte antigen receptor (LAR) (liver) were detected. In contrast,
the expression level of PTPase 1B (PTP 1B) in the skeletal
muscle, but not in liver, was increased by 83% in the diabetic animals,
compared with a diabetes-resistant line. However, PTP 1B–
specific activity (activity/protein) significantly decreased (50% to
56%) in skeletal muscle of diabetic animals, compared with both
the diabetes-resistant line and diabetes-prone animals. In addition,
PTP 1B activity was inversely correlated to serum glucose level
(r = –.434, P < .02). These findings suggest that PTP 1B, though
overexpressed, is not involved in the susceptibility to insulin resistance
in Psammomys obesus and is secondarily attenuated by
hyperglycemia or other factors in the diabetic milieu. |
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