BADERC-Benjamin Neel

Benjamin Neel, M.D. Ph.D.

ProteinTyrosine Phosphatases in Insulin Action

The long range goal of our laboratory is to understand the biological function of several members of the protein-tyrosine phosphatase (PTP) gene family and whether and how mutations and/or altered regulation of PTPs contribute to human disease. At present, we have several ongoing projects with direct relevance to diabetes; this work is being carried out in close collaboration with our colleague, Dr. Barbara Kahn of the Endocrine Division of B.I.D.M.C. First, previous work by several laboratories, most notably that of Barry Goldstein at Thomas Jefferson University, has found that at least two PTPs, a non-transmembrane PTP, PTP-1B, and an transmembrane PTP, LAR, are over-expressed in insulin-resistant states. Since insulin resistance is a post-receptor defect(s), and other work suggest that PTPs are hyperactive in diabetes and other insulin resistant states, these data suggest a potential causal role for these molecules in insulin resistance. However, a direct, in vivo test of the role(s) of these PTPs in normal insulin signaling and/or pathogenesis has not been performed.

We generated and characterized transgenic mice over-expressing LAR selectively in muscle by means of the MCK promoter. These mice are insulin resistant, but do not develop frank diabetes. We have generated an analogous construct that directs PTP-1B expression. These mice also are insulin resistant, but interestingly, preliminary data indicate that when the two are bred to make compound mutants over-expressing both PTPs, there is no further increase in insulin resistance. We plan to continue the latter studies and assess the biochemical effects of combined over-expression on IR signaling.

In addition, to test the role of PTP-1B in normal insulin signaling, we generated PTP-1B knockout mice. Remarkably, PTP1B-/- mice are hypersensitive to insulin. This is due to enhanced IR signaling, consistent with the identification of PTP1B as an insulin receptor phosphatase. Interestingly, our work also showed that insulin sensitivity is tissue specific, affecting fat and liver, but not muscle. Unexpectedly, we also found that PTP1B- mice were resistant to high fat diet induced obesity. In subsequent work, we have found that at least part of this may be explained by regulation of leptin receptor signaling by PTP1B action on Jak2. To clarify the role of PTP1B deficiency further, we have generated a floxed allele of PTP1B and are currently breeding it to liver, fat, muscle and brain-specific Cre lines.

Finally, the SH2 domain containing PTP Shp2 also is implicated in insulin and leptin signaling. We have generated floxed Shp2 mice and are currently breeding them to fat- and muscle-specific Cre lines to assess the function of Shp2 in these signaling pathways in vivo.

References:

1. Venable CL, Frevert EU, Kim Y-B, Fischer BM, Kamatkar S, Neel BG and Kahn BB. Overexpression of protein tyrosine phosphatase-1B in adipocytes inhibits insulin- stimulated phosphoinositide 3-kinase activity with altering glucose transport or Akt/PKB activation. J. Biol. Chem.,2000; 275:26959-66.

2. Klaman LD, Boss O, Peroni OD, Kim JK, Martino JL, Zabolotny JM, Moghal N, Lubkin M, Kim Y-B, Sharpe AH, Stricker- Krongard A, Shulman GI, Neel BG and Kahn BB. Increased energy expenditure, decreased adiposity and tissue-specific insulin sensitivity in protein-tyrosine phosphatase 1B (PTP-1B)-deficient mice. Mol. Cell. Biol., 2000; 20:5479-5489.

3. Zabolotny JM, Kim Y-B, Peroni OD, Kim JK, Pani MA, Boss O, Klaman LD, Kamatkar S, Shulman GI, Kahn BB and Neel BG. Overexpression of the leukocyte antigen-related (LAR) protein tyrosine phosphatase in muscle causes insulin resistance. Proc. Natl. Acad. Sci., 2001 Apr 24;98:5187-92.

4. Bjorbaek C, Buchholz RM, Davis SM, Bates SH, Pierroz DD, Gu H, Neel BG, Myers MG Jr, Flier JS. The role of SHP-2 in MAPK activation by leptin receptors. J Biol Chem., 2001; 276:4747-55.

5. Zabolotny JM, Bence-Hanulec KK, Stricker-Krongard A, Haj F, Wang YP, Minokoshi Y, Kim Y-B, Elmquist JK, Tartaglia LA, Kahn BB and Neel BG. PTP1B regulates leptin signal transduction in vivo. Developmental Cell, 2002; 2:489-49518.

6. Zhang SQ, Tsiaras WG, Araki T, Wen G, Minichiello L, Klein R and Neel BG. Receptor-specific regulation of PI-3K activation by the protein-tyrosine phosphatase Shp2. Mol Cell Biol. 2002; 22:4062-4072.

7. Haj FG, Verveer PJ, Squire A, Neel BG and Bastiaens PIH. Imaging PTP1B/receptor interactions localizes RTK dephosphorylation on the surface of the endoplasmic reticulum. Science, 2002; 295:1708-1711.

8. Haj FG, Markova B, Klaman LD, Bohmer FD, Neel BG. Regulation of receptor tyrosine kinase signaling by protein tyrosine phosphatase-1B (PTP1B). J. Biol. Chem., 2003; 278:739-44.

9. Bates SH, Stearns WH, Dundon TA, Schubert M, Tso AW, Wang Y, Banks AS, Lavery HJ, Haq AK, Maratos-Flier E, Neel BG, Schwartz MW, Myers MG Jr. STAT3 signalling is required for leptin regulation of energy balance but not reproduction. Nature. 2003; 421:856-9.

10. Zhang SQ, Yang W, Kontaridis MI, Bivona TG, Wen G, Araki T, Luo J, Thompson JA, Schraven BL, Philips MR, Neel BG. Shp2 regulates SRC family kinase activity and Ras/Erk activation by controlling Csk recruitment. Mol Cell. 2004;13:341-55.

11. Kushner JA, Haj FG, Klaman LD, Dow MA, Kahn BB, Neel BG, White MF. Islet-sparing effects of protein tyrosine phosphatase-1b deficiency delays onset of diabetes in IRS2 knockout mice. Diabetes. 2004 Jan;53:61-6.






			Benjamin Neel, M.D. Ph.D. ProteinTyrosine Phosphatases in Insulin Action The long range goal of our laboratory is to understand the biological function of several members of the protein-tyrosine phosphatase (PTP) gene family and whether and how mutations and/or altered regulation of PTPs contribute to human disease. At present, we have several ongoing projects with direct relevance to diabetes; this work is being carried out in close collaboration with our colleague, Dr. Barbara Kahn of the Endocrine Division of B.I.D.M.C. First, previous work by several laboratories, most notably that of Barry Goldstein at Thomas Jefferson University, has found that at least two PTPs, a non-transmembrane PTP, PTP-1B, and an transmembrane PTP, LAR, are over-expressed in insulin-resistant states. Since insulin resistance is a post-receptor defect(s), and other work suggest that PTPs are hyperactive in diabetes and other insulin resistant states, these data suggest a potential causal role for these molecules in insulin resistance. However, a direct, in vivo test of the role(s) of these PTPs in normal insulin signaling and/or pathogenesis has not been performed. We generated and characterized transgenic mice over-expressing LAR selectively in muscle by means of the MCK promoter. These mice are insulin resistant, but do not develop frank diabetes. We have generated an analogous construct that directs PTP-1B expression. These mice also are insulin resistant, but interestingly, preliminary data indicate that when the two are bred to make compound mutants over-expressing both PTPs, there is no further increase in insulin resistance. We plan to continue the latter studies and assess the biochemical effects of combined over-expression on IR signaling. In addition, to test the role of PTP-1B in normal insulin signaling, we generated PTP-1B knockout mice. Remarkably, PTP1B-/- mice are hypersensitive to insulin. This is due to enhanced IR signaling, consistent with the identification of PTP1B as an insulin receptor phosphatase. Interestingly, our work also showed that insulin sensitivity is tissue specific, affecting fat and liver, but not muscle. Unexpectedly, we also found that PTP1B- mice were resistant to high fat diet induced obesity. In subsequent work, we have found that at least part of this may be explained by regulation of leptin receptor signaling by PTP1B action on Jak2. To clarify the role of PTP1B deficiency further, we have generated a floxed allele of PTP1B and are currently breeding it to liver, fat, muscle and brain-specific Cre lines. Finally, the SH2 domain containing PTP Shp2 also is implicated in insulin and leptin signaling. We have generated floxed Shp2 mice and are currently breeding them to fat- and muscle-specific Cre lines to assess the function of Shp2 in these signaling pathways in vivo. References: 1. Venable CL, Frevert EU, Kim Y-B, Fischer BM, Kamatkar S, Neel BG and Kahn BB. Overexpression of protein tyrosine phosphatase-1B in adipocytes inhibits insulin- stimulated phosphoinositide 3-kinase activity with altering glucose transport or Akt/PKB activation. J. Biol. Chem.,2000; 275:26959-66. 2. Klaman LD, Boss O, Peroni OD, Kim JK, Martino JL, Zabolotny JM, Moghal N, Lubkin M, Kim Y-B, Sharpe AH, Stricker- Krongard A, Shulman GI, Neel BG and Kahn BB. Increased energy expenditure, decreased adiposity and tissue-specific insulin sensitivity in protein-tyrosine phosphatase 1B (PTP-1B)-deficient mice. Mol. Cell. Biol., 2000; 20:5479-5489. 3. Zabolotny JM, Kim Y-B, Peroni OD, Kim JK, Pani MA, Boss O, Klaman LD, Kamatkar S, Shulman GI, Kahn BB and Neel BG. Overexpression of the leukocyte antigen-related (LAR) protein tyrosine phosphatase in muscle causes insulin resistance. Proc. Natl. Acad. Sci., 2001 Apr 24;98:5187-92. 4. Bjorbaek C, Buchholz RM, Davis SM, Bates SH, Pierroz DD, Gu H, Neel BG, Myers MG Jr, Flier JS. The role of SHP-2 in MAPK activation by leptin receptors. J Biol Chem., 2001; 276:4747-55. 5. Zabolotny JM, Bence-Hanulec KK, Stricker-Krongard A, Haj F, Wang YP, Minokoshi Y, Kim Y-B, Elmquist JK, Tartaglia LA, Kahn BB and Neel BG. PTP1B regulates leptin signal transduction in vivo. Developmental Cell, 2002; 2:489-49518. 6. Zhang SQ, Tsiaras WG, Araki T, Wen G, Minichiello L, Klein R and Neel BG. Receptor-specific regulation of PI-3K activation by the protein-tyrosine phosphatase Shp2. Mol Cell Biol. 2002; 22:4062-4072. 7. Haj FG, Verveer PJ, Squire A, Neel BG and Bastiaens PIH. Imaging PTP1B/receptor interactions localizes RTK dephosphorylation on the surface of the endoplasmic reticulum. Science, 2002; 295:1708-1711. 8. Haj FG, Markova B, Klaman LD, Bohmer FD, Neel BG. Regulation of receptor tyrosine kinase signaling by protein tyrosine phosphatase-1B (PTP1B). J. Biol. Chem., 2003; 278:739-44. 9. Bates SH, Stearns WH, Dundon TA, Schubert M, Tso AW, Wang Y, Banks AS, Lavery HJ, Haq AK, Maratos-Flier E, Neel BG, Schwartz MW, Myers MG Jr. STAT3 signalling is required for leptin regulation of energy balance but not reproduction. Nature. 2003; 421:856-9. 10. Zhang SQ, Yang W, Kontaridis MI, Bivona TG, Wen G, Araki T, Luo J, Thompson JA, Schraven BL, Philips MR, Neel BG. Shp2 regulates SRC family kinase activity and Ras/Erk activation by controlling Csk recruitment. Mol Cell. 2004;13:341-55. 11. Kushner JA, Haj FG, Klaman LD, Dow MA, Kahn BB, Neel BG, White MF. Islet-sparing effects of protein tyrosine phosphatase-1b deficiency delays onset of diabetes in IRS2 knockout mice. Diabetes. 2004 Jan;53:61-6.