Quantification of changes in human islet G protein‐coupled receptor mRNA expression in obesity

Abstract

Background G protein‐coupled receptors (GPCRs) play crucial roles in regulating islet function, with Gαs‐ and Gαq‐coupled receptors being linked to the stimulation of insulin secretion. We have quantified the mRNA expression of 384 non‐olfactory GPCRs in islets isolated from lean and obese organ donors to determine alterations in islet GPCR mRNA expression in obesity. Methods RT‐qPCR was used to quantify GPCR mRNAs relative to five reference genes (ACTB, GAPDH, PPIA, TBP, and TFRC) in human islets isolated from lean (BMI = 22.6 ± 0.5) and obese (BMI = 32.0 ± 0.8) donors. Results Overall, 197 and 256 GPCR mRNAs were detected above trace level in islets from lean and obese donors, respectively, with 191 GPCR mRNAs being common to the lean and obese groups. 40.9% (n = 157) and 27.1% (n = 104) of the mRNAs were expressed at trace level whilst 7.8% and 6.3% were absent in islets from lean and obese donors, respectively. Hundred and seventeen GPCR mRNAs were upregulated at least twofold in islets from obese donors, and there was >twofold downregulation of 21 GPCR mRNAs. Of particular interest, several receptors signalling via Gαs or Gαq showed significant mRNA upregulation in islets from obese donors (fold increase: PTH2R: 54.0 ± 14.6; MC2R: 34.3 ± 11.5; RXFP1: 8.5 ± 2.1; HTR2B: 6.0 ± 2.0; GPR110: 3.9 ± 1.2; PROKR2: 3.9 ± 0.7). Conclusions Under conditions of obesity, human islets showed significant alterations in mRNAs encoding numerous GPCRs. The increased expression of Gαs‐ and Gαq‐coupled receptors that have not previously been investigated in β‐cells opens up possibilities of novel therapeutic candidates that may lead to the potentiation of insulin secretion and/or β‐cell mass to regulate glucose homeostasis.

Mesenchymal stromal cell secretory molecules improve the functional survival of human islets

“…RNA was extracted from human islets using TRIzol, as previously described 26 . The purity and concentration of isolated RNAs were measured using a Nanodrop 1000 spectrophotometer.…”

“…The purity and concentration of isolated RNAs were measured using a Nanodrop 1000 spectrophotometer. Quality approved RNA samples were stored at −80°C prior to reverse transcription of mRNAs 26 . Qiagen QuantiTect primers were used to quantify the expression of individual mRNAs relative to the housekeeping genes (Beta‐actin, ACTB) using the ΔΔCt method.…”

“…Human islets isolated from ethically approved heart-beating donors (seven men/two women; Age: 36-57; BMI: [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] were supplied by King's College London Hospital Human tolerance in graft recipients, consistent with enhanced functional survival of the treated islets in vivo.…”

Stellar science: Basic science has lift off!

“…Rory McCrimmon, 9 this year's Dorothy Hodgkin Lecture recipient, has written an engaging overview of his prize lecture in which he has provided mechanistic insights into recurrent hypoglycaemia in diabetes. We are confident that the articles in this special issue, which are a mixture of primary research, [1][2][3][4][5]7 and state of the art reviews, 6,8,9 are accessible to nonspecialists and will be enjoyed by a wide readership.…”

“…We followed a similar strategy for this year's Basic Science Special Issue, for which we invited submissions from both early stage and more established researchers. We have four stimulating articles from PhD students who were nominated for the Diabetes UK 2022 Basic Science Poster Award (Zekun Lyu, 1 Tanyel Ashik, 2 Lydia Daniels‐Gatward 3 and Claire Williams 4 ), all of whom clearly have much to offer in their respective fields. There are also two high‐quality articles from the Diabetes UK 2022 Early Career Investigator Award nominees (Beth Williams 5 and the prize winner Ed Olaniru 6 ) who both wrote compelling articles in their specialist areas.…”