Temporal Transcriptome Analysis Reveals Dynamic Gene Expression Patterns Driving β-Cell Maturation

Abstract

Newly differentiated pancreatic β cells lack proper insulin secretion profiles of mature functional β cells. The global gene expression differences between paired immature and mature β cells have been studied, but the dynamics of transcriptional events, correlating with temporal development of glucose-stimulated insulin secretion (GSIS), remain to be fully defined. This aspect is important to identify which genes and pathways are necessary for β-cell development or for maturation, as defective insulin secretion is linked with diseases such as diabetes. In this study, we assayed through RNA sequencing the global gene expression across six β-cell developmental stages in mice, spanning from β-cell progenitor to mature β cells. A computational pipeline then selected genes differentially expressed with respect to progenitors and clustered them into groups with distinct temporal patterns associated with biological functions and pathways. These patterns were finally correlated with experimental GSIS, calcium influx, and insulin granule formation data. Gene expression temporal profiling revealed the timing of important biological processes across β-cell maturation, such as the deregulation of β-cell developmental pathways and the activation of molecular machineries for vesicle biosynthesis and transport, signal transduction of transmembrane receptors, and glucose-induced Ca2+ influx, which were established over a week before β-cell maturation completes. In particular, β cells developed robust insulin secretion at high glucose several days after birth, coincident with the establishment of glucose-induced calcium influx. Yet the neonatal β cells displayed high basal insulin secretion, which decreased to the low levels found in mature β cells only a week later. Different genes associated with calcium-mediated processes, whose alterations are linked with insulin resistance and deregulation of glucose homeostasis, showed increased expression across β-cell stages, in accordance with the temporal acquisition of proper GSIS. Our temporal gene expression pattern analysis provided a comprehensive database of the underlying molecular components and biological mechanisms driving β-cell maturation at different temporal stages, which are fundamental for better control of the in vitro production of functional β cells from human embryonic stem/induced pluripotent cell for transplantation-based type 1 diabetes therapy.

mTORC1 is required for epigenetic silencing during β-cell functional maturation

“…Pancreatic β-cell plays a crucial role in maintaining normal glucose homeostasis. A large-scale rewiring of transcriptional programs have proposed that downregulation of β-cell immature genes is required for transition from β-cell progenitor to mature β-cells [ 8 , 29 ]. Immature genes, such as Mafb [ 30 ], Pdgfrα [ 31 ] and Prdm16 [ 32 ], are highly expressed in β-cell progenitors, promote differentiation or proliferation to expand β-cell mass.…”

EZH2 inhibitors promote β-like cell regeneration in young and adult type 1 diabetes donors

“…We also observe trends in transcriptional expression indices (TEI) for pancreatic β-cell maturation that include PAX4 , NKX6-1 , NKX2-2 , KAT2B , ONECUT , HNF1A , GCK , MAFA and PDX1 . 25 Furthermore, we observe strong correspondence with NGN3 + progenitor and pancreatic precursor pathways with transcriptional expression of FGF10, PTF1A, NKX6-1, NKX2-2, KAT2B, PDX1, PAX4 and ONECUT3 indicative of endocrine progenitor specification and β-cell development. 26 Differential expression in the IGF pathway genes such as FGA, VWA1, TGOLN2, ALB, CTSG, IL6, APOB , and FUCA2 indicate regulatory roles in IGF signalling essential for β-cell proliferation and survival.…”

Type 2 Diabetes Mellitus: Pathogenic Features and Experimental Models in Rodents

“…С помощью нокаутных и трансгенных мышей получено понимание того, какие факторы транскрипции участвуют в развитии поджелудочной железы и каковы пути передачи сигналов инсулина. Тканеспецифические нокауты оказались особенно полезными при изучении передачи сигналов инсулина, поскольку мыши с глобальным нокаутом рецептора инсулина нежизнеспособны [119][120][121][122][123].…”

“…The use of knockout and transgenic mice made it possible to identify the transcription factors involved in the pancreas development and insulin signaling pathways. Tissue-specific knockouts turned out to be particularly useful in studying insulin signaling, since mice with global knockout of the insulin receptor are not viable [ 119 , 120 , 121 , 122 , 123 ].…”