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Glucose and glycerol transport in adipocytes from a structural perspective

Huang, Peng LU (2022) In Lund University, Faculty of Medicine Doctoral Dissertation Series
Abstract
Adipocytes are crucial energy reservoirs to maintain metabolic homeostasis of glucose and lipids in the human body.
Glucose transporters (GLUTs) and aquaporins (AQPs) play an important role in metabolic regulation of glucose and
lipids in human adipocytes. Specifically, glucose transporter 4 (GLUT4) and aquaporin 7 (AQP7) are the central
players for glucose transport and glycerol efflux in adipocytes. In addition, GLUT family members are overexpressed
in a vast majority of cancer cells to satisfy their increased energy demand, thus, inhibitors targeting GLUTs are
becoming relevant therapeutics for cancers treatment. To control the uptake/release of nutrients, GLUTs and AQPs
have been suggested to be controlled by... (More)
Adipocytes are crucial energy reservoirs to maintain metabolic homeostasis of glucose and lipids in the human body.
Glucose transporters (GLUTs) and aquaporins (AQPs) play an important role in metabolic regulation of glucose and
lipids in human adipocytes. Specifically, glucose transporter 4 (GLUT4) and aquaporin 7 (AQP7) are the central
players for glucose transport and glycerol efflux in adipocytes. In addition, GLUT family members are overexpressed
in a vast majority of cancer cells to satisfy their increased energy demand, thus, inhibitors targeting GLUTs are
becoming relevant therapeutics for cancers treatment. To control the uptake/release of nutrients, GLUTs and AQPs
have been suggested to be controlled by trafficking mechanisms. TUG (tether containing UBX domain for GLUT4
in mouse) and PLIN1 (human perilipin 1) have previously been suggested to bind with GLUT4 and AQP7
intracellularly and release them upon hormonal stimulation. Here, the mRNA expression levels of GLUTs and AQPs
in adipose tissue has been investigated, and detailed characterization of the interaction between GLUT4 and ASPL
(human TUG homolog) and AQP7 and PLIN1 in vitro have been executed. In addition, a new series of glucose
transporter 1 (GLUT1) inhibitors was structurally and functionally investigated. Finally, the AQP7 structure was
elucidated by single particle cryo-EM.
In this thesis I suggest that GLUT4 interacts with ASPL using its intracellular helical domain to bind to the Cterminus
of ASPL. Rat GLUT4 was expressed in Pichia pastoris, and purified, and showing even single-particle
distribution in negative staining, providing insight on further structural study of GLUT4 by single particle cryo-EM.
Docking models of the complex of GLUT4 and ASPL were generated and suggest that ASPL forms complex with
GLUT4 by multiple domains including both ubiquitin-like domain (UBL2) and ubiquitin domain (UBX). In addition,
PGL13 and PGL14, as new series of GLUT1 inhibitors were suggested to utilize two sites of GLUT1, the
transmembrane domain and intracellular helical domain. Moreover, in human adipocytes AQP7 gene showed
markedly higher-level expression than other aquaglyceroporins. The C-terminal domain of PLIN1 was suggested
to be central for the complex formation with AQP7 and AQP3. The AQP7 structure was determined at the
resolution of 2.55 Å by cryo-EM, adopting the formation of dimer of tetramers. Two tetramers were dimerized by
extracellular protruding C loops with a rotation of approximate 11° around central axis. The central pore is formed
by four monomers and restricted by two leucine filters. Moreover, well-defined densities were discovered in the
central pores showing decent fitting with some small metabolic products. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Drew, David, Stockholm University
organization
publishing date
type
Thesis
publication status
published
subject
keywords
adipocytes, glucose and glycerol metabolism, glucose transporters, aquaglyceroporins, glucose transporter 4, aquaglyceroporin 7, protein and protein interaction, structure, single particle cryo-EM
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
issue
2022:8
pages
85 pages
publisher
Lund University, Faculty of Medicine
defense location
Segerfalksalen, BMC A10, Sölvegatan 17 i Lund. Join by Zoom: https://lu-se.zoom.us/j/69869391433
defense date
2022-01-27 13:00:00
ISSN
1652-8220
ISBN
978-91-8021-169-7
language
English
LU publication?
yes
id
7754e017-032e-485c-aa10-e2eabad0b558
date added to LUP
2021-12-03 14:57:59
date last changed
2022-01-06 09:03:01
@phdthesis{7754e017-032e-485c-aa10-e2eabad0b558,
  abstract     = {{Adipocytes are crucial energy reservoirs to maintain metabolic homeostasis of glucose and lipids in the human body.<br/>Glucose transporters (GLUTs) and aquaporins (AQPs) play an important role in metabolic regulation of glucose and<br/>lipids in human adipocytes. Specifically, glucose transporter 4 (GLUT4) and aquaporin 7 (AQP7) are the central<br/>players for glucose transport and glycerol efflux in adipocytes. In addition, GLUT family members are overexpressed<br/>in a vast majority of cancer cells to satisfy their increased energy demand, thus, inhibitors targeting GLUTs are<br/>becoming relevant therapeutics for cancers treatment. To control the uptake/release of nutrients, GLUTs and AQPs<br/>have been suggested to be controlled by trafficking mechanisms. TUG (tether containing UBX domain for GLUT4<br/>in mouse) and PLIN1 (human perilipin 1) have previously been suggested to bind with GLUT4 and AQP7<br/>intracellularly and release them upon hormonal stimulation. Here, the mRNA expression levels of GLUTs and AQPs<br/>in adipose tissue has been investigated, and detailed characterization of the interaction between GLUT4 and ASPL<br/>(human TUG homolog) and AQP7 and PLIN1 in vitro have been executed. In addition, a new series of glucose<br/>transporter 1 (GLUT1) inhibitors was structurally and functionally investigated. Finally, the AQP7 structure was<br/>elucidated by single particle cryo-EM.<br/>In this thesis I suggest that GLUT4 interacts with ASPL using its intracellular helical domain to bind to the Cterminus<br/>of ASPL. Rat GLUT4 was expressed in Pichia pastoris, and purified, and showing even single-particle<br/>distribution in negative staining, providing insight on further structural study of GLUT4 by single particle cryo-EM.<br/>Docking models of the complex of GLUT4 and ASPL were generated and suggest that ASPL forms complex with<br/>GLUT4 by multiple domains including both ubiquitin-like domain (UBL2) and ubiquitin domain (UBX). In addition,<br/>PGL13 and PGL14, as new series of GLUT1 inhibitors were suggested to utilize two sites of GLUT1, the<br/>transmembrane domain and intracellular helical domain. Moreover, in human adipocytes AQP7 gene showed<br/>markedly higher-level expression than other aquaglyceroporins. The C-terminal domain of PLIN1 was suggested<br/>to be central for the complex formation with AQP7 and AQP3. The AQP7 structure was determined at the<br/>resolution of 2.55 Å by cryo-EM, adopting the formation of dimer of tetramers. Two tetramers were dimerized by<br/>extracellular protruding C loops with a rotation of approximate 11° around central axis. The central pore is formed<br/>by four monomers and restricted by two leucine filters. Moreover, well-defined densities were discovered in the<br/>central pores showing decent fitting with some small metabolic products.}},
  author       = {{Huang, Peng}},
  isbn         = {{978-91-8021-169-7}},
  issn         = {{1652-8220}},
  keywords     = {{adipocytes; glucose and glycerol metabolism; glucose transporters; aquaglyceroporins; glucose transporter 4; aquaglyceroporin 7; protein and protein interaction; structure; single particle cryo-EM}},
  language     = {{eng}},
  number       = {{2022:8}},
  publisher    = {{Lund University, Faculty of Medicine}},
  school       = {{Lund University}},
  series       = {{Lund University, Faculty of Medicine Doctoral Dissertation Series}},
  title        = {{Glucose and glycerol transport in adipocytes from a structural perspective}},
  url          = {{https://lup.lub.lu.se/search/files/111098776/Peng_Huang_thesis_web.pdf}},
  year         = {{2022}},
}