TY - JOUR

T1 - RNA sequencing unravels novel L cell constituents and mechanisms of GLP-1 secretion in human gastric bypass-operated intestine

AU - Miskelly, Michael G.

AU - Lindqvist, Andreas

AU - Piccinin, Elena

AU - Hamilton, Alexander

AU - Cowan, Elaine

AU - Nergård, Bent Johnny

AU - Del Giudice, Rita

AU - Ngara, Mtakai

AU - Cataldo, Luis R.

AU - Kryvokhyzha, Dmytro

AU - Volkov, Petr

AU - Engelking, Luke

AU - Artner, Isabella

AU - Lagerstedt, Jens O.

AU - Eliasson, Lena

AU - Ahlqvist, Emma

AU - Moschetta, Antonio

AU - Hedenbro, Jan

AU - Wierup, Nils

N1 - Publisher Copyright: © 2023, The Author(s).

PY - 2023

Y1 - 2023

N2 - Aims/hypothesis: Roux-en-Y gastric bypass surgery (RYGB) frequently results in remission of type 2 diabetes as well as exaggerated secretion of glucagon-like peptide-1 (GLP-1). Here, we assessed RYGB-induced transcriptomic alterations in the small intestine and investigated how they were related to the regulation of GLP-1 production and secretion in vitro and in vivo. Methods: Human jejunal samples taken perisurgically and 1 year post RYGB (n=13) were analysed by RNA-seq. Guided by bioinformatics analysis we targeted four genes involved in cholesterol biosynthesis, which we confirmed to be expressed in human L cells, for potential involvement in GLP-1 regulation using siRNAs in GLUTag and STC-1 cells. Gene expression analyses, GLP-1 secretion measurements, intracellular calcium imaging and RNA-seq were performed in vitro. OGTTs were performed in C57BL/6j and iScd1 −/− mice and immunohistochemistry and gene expression analyses were performed ex vivo. Results: Gene Ontology (GO) analysis identified cholesterol biosynthesis as being most affected by RYGB. Silencing or chemical inhibition of stearoyl-CoA desaturase 1 (SCD1), a key enzyme in the synthesis of monounsaturated fatty acids, was found to reduce Gcg expression and secretion of GLP-1 by GLUTag and STC-1 cells. Scd1 knockdown also reduced intracellular Ca2+ signalling and membrane depolarisation. Furthermore, Scd1 mRNA expression was found to be regulated by NEFAs but not glucose. RNA-seq of SCD1 inhibitor-treated GLUTag cells identified altered expression of genes implicated in ATP generation and glycolysis. Finally, gene expression and immunohistochemical analysis of the jejunum of the intestine-specific Scd1 knockout mouse model, iScd1 −/−, revealed a twofold higher L cell density and a twofold increase in Gcg mRNA expression. Conclusions/interpretation: RYGB caused robust alterations in the jejunal transcriptome, with genes involved in cholesterol biosynthesis being most affected. Our data highlight SCD as an RYGB-regulated L cell constituent that regulates the production and secretion of GLP-1. Graphical Abstract: [Figure not available: see fulltext.]

AB - Aims/hypothesis: Roux-en-Y gastric bypass surgery (RYGB) frequently results in remission of type 2 diabetes as well as exaggerated secretion of glucagon-like peptide-1 (GLP-1). Here, we assessed RYGB-induced transcriptomic alterations in the small intestine and investigated how they were related to the regulation of GLP-1 production and secretion in vitro and in vivo. Methods: Human jejunal samples taken perisurgically and 1 year post RYGB (n=13) were analysed by RNA-seq. Guided by bioinformatics analysis we targeted four genes involved in cholesterol biosynthesis, which we confirmed to be expressed in human L cells, for potential involvement in GLP-1 regulation using siRNAs in GLUTag and STC-1 cells. Gene expression analyses, GLP-1 secretion measurements, intracellular calcium imaging and RNA-seq were performed in vitro. OGTTs were performed in C57BL/6j and iScd1 −/− mice and immunohistochemistry and gene expression analyses were performed ex vivo. Results: Gene Ontology (GO) analysis identified cholesterol biosynthesis as being most affected by RYGB. Silencing or chemical inhibition of stearoyl-CoA desaturase 1 (SCD1), a key enzyme in the synthesis of monounsaturated fatty acids, was found to reduce Gcg expression and secretion of GLP-1 by GLUTag and STC-1 cells. Scd1 knockdown also reduced intracellular Ca2+ signalling and membrane depolarisation. Furthermore, Scd1 mRNA expression was found to be regulated by NEFAs but not glucose. RNA-seq of SCD1 inhibitor-treated GLUTag cells identified altered expression of genes implicated in ATP generation and glycolysis. Finally, gene expression and immunohistochemical analysis of the jejunum of the intestine-specific Scd1 knockout mouse model, iScd1 −/−, revealed a twofold higher L cell density and a twofold increase in Gcg mRNA expression. Conclusions/interpretation: RYGB caused robust alterations in the jejunal transcriptome, with genes involved in cholesterol biosynthesis being most affected. Our data highlight SCD as an RYGB-regulated L cell constituent that regulates the production and secretion of GLP-1. Graphical Abstract: [Figure not available: see fulltext.]

KW - Gastric bypass surgery

KW - GLP-1

KW - Glucagon-like peptide-1

KW - Intestine

KW - Obesity

KW - Remission

KW - RNA sequencing

KW - SCD

KW - Stearoyl-CoA desaturase

KW - Type 2 diabetes

U2 - 10.1007/s00125-023-06046-8

DO - 10.1007/s00125-023-06046-8

M3 - Journal article

C2 - 38032369

AN - SCOPUS:85178171702

VL - 67

SP - 356

EP - 370

JO - Diabetologia

JF - Diabetologia

SN - 0012-186X

IS - 2

ER -