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Identification of skeletal muscle protein-tyrosine phosphatases by amplification of conserved cDNA sequences
1Research Division, Joslin Diabetes Center, Brigham and Women's Hospital, Boston, MA.
Abstract:
Specific protein-tyrosine phosphatase (PTPase) enzymes that regulate signal transduction by the insulin receptor in target tissues have not been identified. We evaluated the expression of PTPase homologs in skeletal muscle since this tissue is the major site of insulin-mediated glucose disposal in vivo. A rat skeletal muscle cDNA pool was prepared with a set of degenerate oligonucleotide primers and PTPase cDNA sequences were amplified using pairs of "guess-mers" that were deduced from highly conserved residues within the known catalytic domains of these enzymes. Sequences encoding three "receptor-like" transmembrane PTPases were identified and two of these (known as LAR and LRP) were confirmed to be expressed in muscle by subsequent cDNA library screening and Northern blot analysis. The expression of the LAR and LRP PTPases in skeletal muscle suggests that these enzymes might have a role in the regulation of insulin action in muscle and other insulin-sensitive tissues.
Insights
Researchers identified specific protein-tyrosine phosphatase (PTPase) enzymes, LAR and LRP, expressed in skeletal muscle. This finding suggests their potential role in regulating insulin action and glucose disposal in insulin-sensitive tissues.
Area of Science:
- Molecular Biology
- Biochemistry
- Physiology
Background:
- Specific protein-tyrosine phosphatase (PTPase) enzymes regulating insulin receptor signal transduction remain unidentified.
- Skeletal muscle is a primary site for insulin-mediated glucose disposal in vivo.
- Understanding PTPase involvement is crucial for elucidating insulin action mechanisms.
Purpose of the Study:
- To identify PTPase homologs expressed in skeletal muscle.
- To investigate the potential role of identified PTPases in insulin signaling within muscle tissue.
Main Methods:
- Preparation of a rat skeletal muscle cDNA pool.
- Amplification of PTPase cDNA sequences using degenerate oligonucleotide primers and deduced "guess-mers".
- Confirmation of PTPase expression via cDNA library screening and Northern blot analysis.
Main Results:
- Identification of sequences encoding three "receptor-like" transmembrane PTPases.
- Confirmation of LAR and LRP PTPase expression in skeletal muscle.
- Demonstration of LAR and LRP PTPase presence in a key tissue for glucose metabolism.
Conclusions:
- LAR and LRP PTPases are expressed in skeletal muscle.
- These PTPases may play a significant role in regulating insulin action in muscle.
- Further research into LAR and LRP PTPases could reveal novel therapeutic targets for metabolic disorders.