RETRACTED ARTICLE: Calcium-dependent transcriptional changes in human pancreatic islet cells reveal functional diversity in islet cell subtypes

• Published in: Diabetologia 2022-09, Vol.65 (9), p.1519-1533
• Main Authors: Yoon, Ji Soo, Sasaki, Shugo, Velghe, Jane, Lee, Michelle Y. Y., Winata, Helena, Nian, Cuilan, Lynn, Francis C.
• Format: Article
• Language: English
• Subjects: Human Physiology; Internal Medicine; Medicine; Medicine & Public Health; Metabolic Diseases
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-022-05718-1

Aims/hypothesis Pancreatic islets depend on cytosolic calcium (Ca 2+ ) to trigger the secretion of glucoregulatory hormones and trigger transcriptional regulation of genes important for islet response to stimuli. To date, there has not been an attempt to profile Ca 2+ -regulated gene expression in all islet cell types. Our aim was to construct a large single-cell transcriptomic dataset from human islets exposed to conditions that would acutely induce or inhibit intracellular Ca 2+ signalling, while preserving biological heterogeneity. Methods We exposed intact human islets from three donors to the following conditions: (1) 2.8 mmol/l glucose; (2) 16 mmol/l glucose and 40 mmol/l KCl to maximally stimulate Ca 2+ signalling; and (3) 16 mmol/l glucose, 40 mmol/l KCl and 5 mmol/l EGTA (Ca 2+ chelator) to inhibit Ca 2+ signalling, for 1 h. We sequenced 68,650 cells from all islet cell types, and further subsetted the cells to form an endocrine cell-specific dataset of 59,373 cells expressing INS , GCG , SST or PPY . We compared transcriptomes across conditions to determine the differentially expressed Ca 2+ -regulated genes in each endocrine cell type, and in each endocrine cell subcluster of alpha and beta cells. Results Based on the number of Ca 2+ -regulated genes, we found that each alpha and beta cell cluster had a different magnitude of Ca 2+ response. We also showed that polyhormonal clusters expressing both INS and GCG , or both INS and SST , are defined by Ca 2+ -regulated genes specific to each cluster. Finally, we identified the gene PCDH7 from the beta cell clusters that had the highest number of Ca 2+ -regulated genes, and showed that cells expressing cell surface PCDH7 protein have enhanced glucose-stimulated insulin secretory function. Conclusions/interpretation Here we use our large-scale, multi-condition, single-cell dataset to show that human islets have cell-type-specific Ca 2+ -regulated gene expression profiles, some of them specific to subpopulations. In our dataset, we identify PCDH7 as a novel marker of beta cells having an increased number of Ca 2+ -regulated genes and enhanced insulin secretory function. Data availability A searchable and user-friendly format of the data in this study, specifically designed for rapid mining of single-cell RNA sequencing data, is available at https://lynnlab.shinyapps.io/Human_Islet_Atlas/ . The raw data files are available at NCBI Gene Expression Omnibus (GSE196715). Graphical abstract