Transcriptional response of endometrial cells to Insulin, cultured using microfluidics

Obesity is a rapidly growing public health issue among women of reproductive age associated with decreased reproductive function including implantation failure. This can result from a myriad of factors including impaired gametes and endometrial dysfunction. The mechanisms of how obesity-related hyperinsulinaemia disrupts endometrial function are poorly understood. We investigated potential mechanisms by which insulin alters endometrial transcript expression. Ishikawa cells were seeded into a microfluidics device attached to a syringe pump to deliver a constant flow rate of 1uL/min of the following: 1) control 2) vehicle control (acetic acid) or, 3) Insulin (10 ng/ml) for 24 hours (n=3 biological replicates). Insulin-induced transcriptomic response of endometrial epithelial cells was determined via RNA sequencing, and DAVID and Webgestalt to identify Gene Ontology (GO) terms and signalling pathways. A Total of 29 transcripts showed differential expression levels across two comparison groups (control v vehicle control; vehicle control v insulin). Nine transcripts were differentially expressed in vehicle control v insulin comparison (p<0.05). Functional annotation analysis of transcripts altered by insulin (n=9) identified three significantly enriched GO terms: SRP-dependent cotranslational protein targeting to membrane, poly(A) binding, and RNA binding (p<0.05). Over-representation analysis found three significantly enriched signalling pathways relating to insulin-induced transcriptomic response: protein export, glutathione metabolism, and ribosome pathways (p<0.05). Transfection of siRNA for RASPN successfully knocked down expression (p<0.05) but this did not have any effect on cellular morphology. Insulin-induced dysregulation of biological functions and pathways highlight potential mechanisms by which high insulin concentrations within maternal circulation may perturb endometrial receptivity.