Expression of protein-tyrosine phosphatases in the major insulin target tissues.
Protein-tyrosine phosphatases (PTPs) are key regulators of the insulin receptor signal transduction pathway. We have performed a detailed analysis of PTP expression in the major human insulin target tissues or cells (liver, adipose tissue, skeletal muscle and endothelial cells). To obtain a representative picture, all tissues were analyzed by PCR using three different primer sets corresponding to conserved regions of known PTPs. A total of 24 different PTPs were identified. A multiprobe RNase protection assay was developed to obtain a semiquantitative measure of the expression levels of selected PTPs. Surprisingly, PTP-LAR, previously suggested to be a major regulator of the insulin receptor tyrosine kinase, was expressed in extremely low levels in skeletal muscle, whereas the related receptor-type PTP-sigma and PTP-alpha were expressed in relatively high levels in all four tissues. The low levels of LAR PTP mRNA in skeletal muscle were further confirmed by Northern blot analysis.
Norris
K
K
Vessel Wall Biology, Novo Nordisk, Gentofte, Denmark. kn@novo.dk
Norris
F
F
Kono
D H
DH
Vestergaard
H
H
Pedersen
O
O
Theofilopoulos
A N
AN
Møller
N P
NP
D000273:Adipose Tissue / Q000201:enzymology / Q000378:metabolism; D015152:Blotting, Northern; D017931:DNA Primers; D004730:Endothelium, Vascular / Q000201:enzymology / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism; D010920:Placenta / Q000201:enzymology / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000235:genetics*; D015347:RNA Probes; D012333:RNA, Messenger / Q000032:analysis; D011972:Receptor, Insulin / Q000502:physiology*; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D011956:Receptors, Cell Surface; D012260:Ribonucleases / Q000378:metabolism; D015398:Signal Transduction
D017931:DNA Primers; D007527:Isoenzymes; D015347:RNA Probes; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D011972:Receptor, Insulin; D012260:Ribonucleases; C516841:PTPRA protein, human; D017027:Protein Tyrosine Phosphatases; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4