Vitamin D-binding protein/GC-globulin: a novel regulator of alpha cell function and glucagon secretion

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@article{609d0a35a27e465b8d2519a3ce689ee3,
title = "Vitamin D-binding protein/GC-globulin: a novel regulator of alpha cell function and glucagon secretion",
abstract = "The contribution of glucagon to type 1 and type 2 diabetes has long been known, but the underlying defects in alpha cell function are not well‐described. During both disease states, alpha cells respond inappropriately to stimuli, leading to dysregulated glucagon secretion, impaired glucose tolerance and hypoglycaemia. The mechanisms involved in this dysfunction are complex, but possibly include changes in alpha cell glucose‐sensing, alpha cell de‐differentiation, paracrine feedback, as well as alpha cell mass. However, the molecular underpinnings of alpha cell failure are still poorly understood. Recent transcriptomic analyses have identified vitamin D binding protein (DBP), encoded by GC/Gc, as an alpha cell signature gene. DBP is highly localized to the liver and alpha cells and is virtually absent from other tissues and cell types under non‐pathological conditions. While the vitamin D transportation role of DBP is well characterized in the liver and circulation, its function in alpha cells remains more enigmatic. Recent work reveals that loss of DBP leads to smaller and hyperplastic alpha cells, which secrete less glucagon in response to low glucose concentration, despite vitamin D sufficiency. Alpha cells lacking DBP display impaired Ca2+ fluxes and Na+ conductance, as well as changes in glucagon granule distribution. Underlying these defects is an increase in the ratio of cytoskeletal F‐actin to G‐actin, highlighting a novel intracellular actin scavenging role for DBP in islets.",
keywords = "GC, GC-globulin, alpha cell, glucagon, metabolism, type 1 diabetes, type 2 diabetes, vitamin D, vitamin D-binding protein",
author = "Katrina Viloria and Martin Hewison and David Hodson",
note = "Funding Information: D.J.H. was supported by MRC (MR/N00275X/1 and MR/S025618/1) and Diabetes UK (17/0005681) Project Grants. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Starting Grant 715884 to D.J.H.). Publisher Copyright: {\textcopyright} 2021 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society",
year = "2021",
month = mar,
day = "15",
doi = "10.1113/JP280890",
language = "English",
journal = "The Journal of Physiology",
issn = "0022-3751",
publisher = "Wiley",

}

RIS

TY - JOUR

T1 - Vitamin D-binding protein/GC-globulin

T2 - a novel regulator of alpha cell function and glucagon secretion

AU - Viloria, Katrina

AU - Hewison, Martin

AU - Hodson, David

N1 - Funding Information: D.J.H. was supported by MRC (MR/N00275X/1 and MR/S025618/1) and Diabetes UK (17/0005681) Project Grants. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Starting Grant 715884 to D.J.H.). Publisher Copyright: © 2021 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society

PY - 2021/3/15

Y1 - 2021/3/15

N2 - The contribution of glucagon to type 1 and type 2 diabetes has long been known, but the underlying defects in alpha cell function are not well‐described. During both disease states, alpha cells respond inappropriately to stimuli, leading to dysregulated glucagon secretion, impaired glucose tolerance and hypoglycaemia. The mechanisms involved in this dysfunction are complex, but possibly include changes in alpha cell glucose‐sensing, alpha cell de‐differentiation, paracrine feedback, as well as alpha cell mass. However, the molecular underpinnings of alpha cell failure are still poorly understood. Recent transcriptomic analyses have identified vitamin D binding protein (DBP), encoded by GC/Gc, as an alpha cell signature gene. DBP is highly localized to the liver and alpha cells and is virtually absent from other tissues and cell types under non‐pathological conditions. While the vitamin D transportation role of DBP is well characterized in the liver and circulation, its function in alpha cells remains more enigmatic. Recent work reveals that loss of DBP leads to smaller and hyperplastic alpha cells, which secrete less glucagon in response to low glucose concentration, despite vitamin D sufficiency. Alpha cells lacking DBP display impaired Ca2+ fluxes and Na+ conductance, as well as changes in glucagon granule distribution. Underlying these defects is an increase in the ratio of cytoskeletal F‐actin to G‐actin, highlighting a novel intracellular actin scavenging role for DBP in islets.

AB - The contribution of glucagon to type 1 and type 2 diabetes has long been known, but the underlying defects in alpha cell function are not well‐described. During both disease states, alpha cells respond inappropriately to stimuli, leading to dysregulated glucagon secretion, impaired glucose tolerance and hypoglycaemia. The mechanisms involved in this dysfunction are complex, but possibly include changes in alpha cell glucose‐sensing, alpha cell de‐differentiation, paracrine feedback, as well as alpha cell mass. However, the molecular underpinnings of alpha cell failure are still poorly understood. Recent transcriptomic analyses have identified vitamin D binding protein (DBP), encoded by GC/Gc, as an alpha cell signature gene. DBP is highly localized to the liver and alpha cells and is virtually absent from other tissues and cell types under non‐pathological conditions. While the vitamin D transportation role of DBP is well characterized in the liver and circulation, its function in alpha cells remains more enigmatic. Recent work reveals that loss of DBP leads to smaller and hyperplastic alpha cells, which secrete less glucagon in response to low glucose concentration, despite vitamin D sufficiency. Alpha cells lacking DBP display impaired Ca2+ fluxes and Na+ conductance, as well as changes in glucagon granule distribution. Underlying these defects is an increase in the ratio of cytoskeletal F‐actin to G‐actin, highlighting a novel intracellular actin scavenging role for DBP in islets.

KW - GC

KW - GC-globulin

KW - alpha cell

KW - glucagon

KW - metabolism

KW - type 1 diabetes

KW - type 2 diabetes

KW - vitamin D

KW - vitamin D-binding protein

UR - http://www.scopus.com/inward/record.url?scp=85104513186&partnerID=8YFLogxK

U2 - 10.1113/JP280890

DO - 10.1113/JP280890

M3 - Article

C2 - 33719063

JO - The Journal of Physiology

JF - The Journal of Physiology

SN - 0022-3751

ER -