A Human Variant of Glucose-Regulated Protein 94 That Inefficiently Supports IGF Production

TY - JOUR

T1 - A Human Variant of Glucose-Regulated Protein 94 That Inefficiently Supports IGF Production

AU - Marzec, Michal

AU - Hawkes, Colin P

AU - Eletto, Davide

AU - Boyle, Sarah

AU - Rosenfeld, Ron G

AU - Hwa, Vivian

AU - Wit, Jan M

AU - van Duyvenvoorde, Hermine A

AU - Oostdijk, Wilma

AU - Losekoot, Monique

AU - Pedersen, Oluf

AU - Yeap, Bu Beng

AU - Flicker, Leon

AU - Barzilai, Nir

AU - Atzmon, Gil

AU - Grimberg, Adda

AU - Argon, Yair

PY - 2016/5

Y1 - 2016/5

N2 - IGFs are critical for normal intrauterine and childhood growth and sustaining health throughout life. We showed previously that the production of IGF-1 and IGF-2 requires interaction with the chaperone glucose-regulated protein 94 (GRP94) and that the amount of secreted IGFs is proportional to the GRP94 activity. Therefore, we tested the hypothesis that functional polymorphisms of human GRP94 affect IGF production and thereby human health. We describe a hypomorphic variant of human GRP94, P300L, whose heterozygous carriers have 9% lower circulating IGF-1 concentration. P300L was found first in a child with primary IGF deficiency and was later shown to be a noncommon single-nucleotide polymorphism with frequencies of 1%-4% in various populations. When tested in the grp94(-/-) cell-based complementation assay, P300L supported only approximately 58% of IGF secretion relative to wild-type GRP94. Furthermore, recombinant P300L showed impaired nucleotide binding activity. These in vitro data strongly support a causal relationship between the GRP94 variant and the decreased concentration of circulating IGF-1, as observed in human carriers of P300L. Thus, mutations in GRP94 that affect its IGF chaperone activity represent a novel causal genetic mechanism that limits IGF biosynthesis, quite a distinct mechanism from the known genes in the GH/IGF signaling network.

AB - IGFs are critical for normal intrauterine and childhood growth and sustaining health throughout life. We showed previously that the production of IGF-1 and IGF-2 requires interaction with the chaperone glucose-regulated protein 94 (GRP94) and that the amount of secreted IGFs is proportional to the GRP94 activity. Therefore, we tested the hypothesis that functional polymorphisms of human GRP94 affect IGF production and thereby human health. We describe a hypomorphic variant of human GRP94, P300L, whose heterozygous carriers have 9% lower circulating IGF-1 concentration. P300L was found first in a child with primary IGF deficiency and was later shown to be a noncommon single-nucleotide polymorphism with frequencies of 1%-4% in various populations. When tested in the grp94(-/-) cell-based complementation assay, P300L supported only approximately 58% of IGF secretion relative to wild-type GRP94. Furthermore, recombinant P300L showed impaired nucleotide binding activity. These in vitro data strongly support a causal relationship between the GRP94 variant and the decreased concentration of circulating IGF-1, as observed in human carriers of P300L. Thus, mutations in GRP94 that affect its IGF chaperone activity represent a novel causal genetic mechanism that limits IGF biosynthesis, quite a distinct mechanism from the known genes in the GH/IGF signaling network.

U2 - 10.1210/en.2015-2058

DO - 10.1210/en.2015-2058

M3 - Journal article

C2 - 26982636

SN - 0013-7227

VL - 157

SP - 1914

EP - 1928

JO - Endocrinology

JF - Endocrinology

IS - 5

ER -