TY - JOUR

T1 - Characterization of the Met326Ile variant of phosphatidylinositol 3-kinase p85alpha

AU - Almind, Katrine

AU - Delahaye, Laurent

AU - Hansen, Torben

AU - Van Obberghen, Emmanuel

AU - Pedersen, Oluf

AU - Kahn, C Ronald

PY - 2002/2/19

Y1 - 2002/2/19

N2 - Phosphatidylinositol 3-kinase is a key step in the metabolic actions of insulin. Two amino acid substitutions have been identified in the gene for the regulatory subunit of human p85alpha, Met-326Ile, and Asn-330Asp, and the former has been associated with alterations in glucose/insulin homeostasis. When the four human p85alpha proteins were expressed in yeast, a 27% decrease occurred in the level of protein expression of p85alpha(Ile/Asp) (P = 0.03) and a 43% decrease in p85alpha(Ile/Asn) (P = 0.08) as compared with p85alpha(Met/Asp). Both p85alpha(Ile/Asp) and p85alpha(Ile/Asn) also exhibited increased binding to phospho-insulin receptor substrate-1 by 41% and 83%, respectively (P <0.001), as compared with p85alpha(Met/Asp). The expression of p85alpha(Ile) was also slightly decreased and the binding to insulin receptor substrate-1 slightly increased in brown preadipocytes derived from p85alpha knockout mice. Both p85alpha(Met) and p85alpha(Ile) had similar effects on AKT activity and were able to reconstitute differentiation of the preadipocytes, although the triglyceride concentration in fully differentiated adipocytes and insulin-stimulated 2-deoxyglucose uptake were slightly lower than in adipocytes expressing p85alpha(Met). Thus, the Met-326Ile variant of p85alpha is functional for intracellular signaling and adipocyte differentiation but has small alterations in protein expression and activity that could play a role in modifying insulin action.

AB - Phosphatidylinositol 3-kinase is a key step in the metabolic actions of insulin. Two amino acid substitutions have been identified in the gene for the regulatory subunit of human p85alpha, Met-326Ile, and Asn-330Asp, and the former has been associated with alterations in glucose/insulin homeostasis. When the four human p85alpha proteins were expressed in yeast, a 27% decrease occurred in the level of protein expression of p85alpha(Ile/Asp) (P = 0.03) and a 43% decrease in p85alpha(Ile/Asn) (P = 0.08) as compared with p85alpha(Met/Asp). Both p85alpha(Ile/Asp) and p85alpha(Ile/Asn) also exhibited increased binding to phospho-insulin receptor substrate-1 by 41% and 83%, respectively (P <0.001), as compared with p85alpha(Met/Asp). The expression of p85alpha(Ile) was also slightly decreased and the binding to insulin receptor substrate-1 slightly increased in brown preadipocytes derived from p85alpha knockout mice. Both p85alpha(Met) and p85alpha(Ile) had similar effects on AKT activity and were able to reconstitute differentiation of the preadipocytes, although the triglyceride concentration in fully differentiated adipocytes and insulin-stimulated 2-deoxyglucose uptake were slightly lower than in adipocytes expressing p85alpha(Met). Thus, the Met-326Ile variant of p85alpha is functional for intracellular signaling and adipocyte differentiation but has small alterations in protein expression and activity that could play a role in modifying insulin action.

KW - Adipocytes

KW - Adipose Tissue, Brown

KW - Animals

KW - Cattle

KW - Codon

KW - DNA, Complementary

KW - Dose-Response Relationship, Drug

KW - Genes, Reporter

KW - Glucose

KW - Humans

KW - Insulin

KW - Methionine

KW - Mice

KW - Models, Genetic

KW - Phosphatidylinositol 3-Kinases

KW - Phosphorylation

KW - Plasmids

KW - Protein Binding

KW - Rats

KW - Signal Transduction

KW - Time Factors

KW - Triglycerides

KW - Two-Hybrid System Techniques

U2 - 10.1073/pnas.042688799

DO - 10.1073/pnas.042688799

M3 - Journal article

C2 - 11842213

VL - 99

SP - 2124

EP - 2128

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 4

ER -