caa a22 4500 475771893 CHVBK 20180406123619.0 cr unu---uuuuu 170329e20000301xx s 000 0 eng 10.1007/s001250050050 doi (NATIONALLICENCE)springer-10.1007/s001250050050 Natural variants of human p85 α phosphoinositide 3-kinase in severe insulin resistance: a novel variant with impaired insulin-stimulated lipid kinase activity [Elektronische Daten] [K. C.R. Baynes, C. A. Beeton, G. Panayotou, R. Stein, M. Soos, T. Hansen, H. Simpson, S. O'Rahilly, P. R. Shepherd, J. P. Whitehead] Abstract : Aims/hypothesis. Phosphoinositide 3-kinase (PI 3K) plays a central part in the mediation of insulin-stimulated glucose disposal. No genetic studies of this enzyme in human syndromes of severe insulin resistance have been previously reported.¶Methods. Phosphoinositide 3-kinase p85α regulatory subunit cDNA was examined in 20 subjects with syndromes of severe insulin resistance by single strand conformational polymorphism and restriction fragment length polymorphism analyses. Insulin-stimulated phosphoinositide 3-kinase activity and recruitment into phosphotyrosine complexes of variants of p85α were studied in transiently transfected HEK293 cells. Phosphopeptide binding characteristics of wild-type and mutant p85α-GST fusion proteins were examined by surface plasmon resonance.¶Results. The common p85α variant, Met326I1e, was identified in 9 of the 20 subjects. Functional studies of the Met326Ile variant showed it to have equivalent insulin-stimulated lipid kinase activity and phosphotyrosine recruitment as wild-type p85α. A novel heterozygous mutation, Arg409Gln, was detected in one subject. Within the proband's family, carriers of the mutation had a higher median fasting plasma insulin (218 pmol/l) compared with wild-type relatives (72 mol/l) (n = 8 subjects, p = 0.06). The Arg409Gln p85α subunit was associated with lower insulin-stimulated phosphoinositide 3-kinase activity compared with wild-type (mean reduction 15 %, p < 0.05, n = 5). The recruitment of Arg409Gln p85α into phosphotyrosine complexes was not significantly impaired. GST fusion proteins of wild-type and mutant p85α showed identical binding to phosphopeptides in surface plasmon resonance studies.¶Conclusion/interpretation. Mutations in p85α are uncommon in subjects with syndromes of severe insulin resistance. The Met326Ile p85α variant appears to have no functional effect on the insulin-stimulated phosphoinositide 3-kinase activity. The impaired phosphoinositide 3-kinase activity of the Arg409Gln mutant suggests that it could contribute to the insulin resistance seen in this family. [Diabetologia (2000) 43: 321-331] Springer-Verlag Berlin Heidelberg, 2000 Keywords Keywords Genetics, insulin signalling, phosphatidylinositol 3-kinase nationallicence Baynes K. C.R. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut Beeton C. A. Department of Biochemistry, University College London, UK, GB aut Panayotou G. Ludwig Institute of Cancer Research, London, UK, GB aut Stein R. Ludwig Institute of Cancer Research, London, UK, GB aut Soos M. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut Hansen T. Steno Diabetes Center, Gentofte, Denmark, DK aut Simpson H. Diabetes Centre, Royal Berkshire Hospital, Reading, UK, GB aut O'Rahilly S. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut Shepherd P. R. Department of Biochemistry, University College London, UK, GB aut Whitehead J. P. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut https://doi.org/10.1007/s001250050050 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s001250050050 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Baynes K. C.R. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut NATIONALLICENCE 700 1- Beeton C. A. Department of Biochemistry, University College London, UK, GB aut NATIONALLICENCE 700 1- Panayotou G. Ludwig Institute of Cancer Research, London, UK, GB aut NATIONALLICENCE 700 1- Stein R. Ludwig Institute of Cancer Research, London, UK, GB aut NATIONALLICENCE 700 1- Soos M. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut NATIONALLICENCE 700 1- Hansen T. Steno Diabetes Center, Gentofte, Denmark, DK aut NATIONALLICENCE 700 1- Simpson H. Diabetes Centre, Royal Berkshire Hospital, Reading, UK, GB aut NATIONALLICENCE 700 1- O'Rahilly S. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut NATIONALLICENCE 700 1- Shepherd P. R. Department of Biochemistry, University College London, UK, GB aut NATIONALLICENCE 700 1- Whitehead J. P. Departments of Medicine and Clinical Biochemistry, University of Cambridge, UK, GB aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer