Plasma heat shock protein response to euglycemia in type 2 diabetes

Abstract

Introduction: Glucose variability is associated with mortality and macrovascular diabetes complications. The mechanisms through which glucose variability mediates tissue damage are not well understood, although cellular oxidative stress is likely involved. As heat shock proteins (HSPs) play a role in the pathogenesis of type 2 diabetes (T2D) complications and are rapidly responsive, we hypothesized that HSP-related proteins (HSPRPs) would differ in diabetes and may respond to glucose normalization.

Research design and methods: A prospective, parallel study in T2D (n=23) and controls (n=23) was undertaken. T2D subjects underwent insulin-induced blood glucose normalization from baseline 7.6±0.4 mmol/L (136.8±7.2 mg/dL) to 4.5±0.07 mmol/L (81±1.2 mg/dL) for 1 hour. Control subjects were maintained at 4.9±0.1 mmol/L (88.2±1.8 mg/dL). Slow Off-rate Modified Aptamer-scan plasma protein measurement determined a panel of HSPRPs.

Results: At baseline, E3-ubiquitin-protein ligase (carboxyl-terminus of Hsc70 interacting protein (CHIP) or HSPABP2) was lower (p=0.03) and ubiquitin-conjugating enzyme E2G2 higher (p=0.003) in T2D versus controls. Following glucose normalization, DnaJ homolog subfamily B member 1 (DNAJB1 or HSP40) was reduced (p=0.02) in T2D, with HSP beta-1 (HSPB1) and HSP-70-1A (HSP70-1A) (p=0.07 and p=0.09, respectively) also approaching significance relative to T2D baseline levels.

Conclusions: Key HSPRPs involved in critical protein interactions, CHIP and UBE2G2, were altered in diabetes at baseline. DNAJB1 fell in response to euglycemia, suggesting that HSPs are reacting to basal stress that could be mitigated by tight glucose control with reduction of glucose variability.

Trial registration: ClinicalTrials.gov NCT03102801.

Keywords: blood glucose; diabetes mellitus; type 2.

Conflict of interest statement

Competing interests: None declared.

© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Comparison of HSPs HSP90alpha-A1, HSP90alpha-B1, HSP70-1A, HSP70-8, HSPB1, 60 kDa heat shock protein, mitochondrial (HSPD1), CDC37, and DNAJB1 in plasma at BL and after iatrogenic induction of euglycemia (BM) in T2D subjects. Blood sampling for proteomics was performed at baseline (BL) in controls (white circles) and T2D (black squares) and again at euglycemia (BM) in T2D subjects. Proteomic (Somalogic) analysis of HSP-related proteins was undertaken for HSPs HSP90alpha-A1 (A), HSP90alpha-B1 (B), HSP70-1A (C), HSP70-8 (D), HSPB1 (E), HSPD1 (F), CDC37 (G), and DNAJB1 (H). Statistics: $p

Figure 2

Comparison of HSPs PPID, STIP1, CHIP, UBE2G2 and heat shock protein 90 dimer (HSP90a/b) in plasma at BL and after iatrogenic induction of euglycemia (BM) in T2D subjects. Blood sampling for proteomics was performed at baseline (BL) in controls (white circles) and T2D (black squares) and again at euglycemia (BM) in T2D subjects. Proteomic (Somalogic) analysis of HSP-related proteins was undertaken for HSPs PPID (A), STIP1 (B), CHIP (C), UBE2G2 (D), and HSP90a/b (E). Statistics: * p

Figure 3

Correlation analyses of heat shock proteins. For age, there was a negative correlation with HSP70-1A (A) and HSPD1 (C) in T2D (blue squares) and a positive correlation for HSPB1 (B) in controls (black squares). For BMI, there was a negative correlation with HSPD1 (D) and a positive correlation with UBE2G2 (E). BMI, body mass index; HSP, heat shock protein; HSPB1, HSP beta-1; RFU, relative fluorescent units; T2D, type 2 diabetes; UBE2G2, ubiquitin-conjugating enzyme E2G2.

Figure 4

STRING interaction network showing the interactions of heat shock-related proteins. STRING 11.0 was used to visualize the known and predicted protein-protein interactions for proteins identified by SOMAscan assay in plasma of T2D vs control subjects (https://string-db.org/). Network nodes represent proteins and the lines reflect physical and/or functional interactions of proteins. Empty nodes represent the proteins of unknown three-dimensional structure, and filled nodes represent the proteins with some three-dimensional structure, either known or predicted. Different colored lines between the proteins represent the various types of interaction evidence in STRING (databases, experiments, neighborhood, gene fusion, co-occurrence, text mining, coexpression, and homology): here, known interactions are shown in light blue (from curated databases) and pink (experimentally determined); predicted interactions are shown in dark blue (gene co-occurrence); relationships gleaned from text mining (lime green), coexpression (black), and protein homology (mauve) are also shown. HSP, heat shock protein; HSPB1, HSP beta-1; STRING, Search Tool for the Retrieval of Interacting Genes; T2D, type 2 diabetes; UBE2G2, ubiquitin-conjugating enzyme E2G2.