Biology subjects

Riggs, A. D.

Publications and source records attributed to Riggs, A. D..

3 recordsLinked to original sources

bioRxiv2026

Optimal compositions of potent sliced-siRNA with DNA bases substitution and insights of Ago2 slicing actions

We have previously characterized the nucleotide compositions of single-stranded ago2-sliced small interfering RNAs (sliced-siRNA, sliRNA), a novel type of potent RNAi trigger designed based on the biogenesis mechanism of miRNA-451. sliRNAs have on par antisense mediated silencing activity but about 1000-fold reduced passenger strand activity compared to siRNA. In the current study, to further characterize sliRNAs to facilitate their in vivo application, we have investigated the effects of substituting RNA nucleotides (nts) in sliRNA with DNA nts (sliDRNAs), which will allow us to study the potential effects on their processing, maturation, and silencing activity from individual or multiple nts at different positions. Our results showed sliDRNAs have distinguished composition from siRNA with DNA nts (siDRNA), indicated that, in addition to their different biogenesis mechanisms, these two types of RNAi triggers may also have adopted additional different silencing mechanisms. Our results also revealed some mechanism related to how Ago2 executes its slicer activity and the effects on sliRNA potency by trimming and tailing during sliRNA maturation. These results have paved the way for using other chemically modified nts in sliRNAs that may enhance their in vivo stability and transportability to facilitate their in vivo applications.

molecular biology↗

bioRxiv2024

Multi-omics analysis of long-term cultured human islets

Beta-cell dysfunction in pancreatic islets, characterized as either the loss of beta-cell mass or the resistance of beta-cell to glucose, is the leading cause of progression to diabetes. Islet transplantation became a promising approach to replenish functional beta-cell mass. However, not much known about changes in islets used for transplantation after isolation. We have subjected human islets into long-term in vitro culture (LTC) and characterized those survived islets. While most of the dysregulated genes were downregulated during LTC, specific groups of mRNA or miRNA were upregulated, and they are involved in specific pathways. In general, alpha-cells and beta-cells of LTC-islets have elevated expressions of MAFB and MAFA genes, respectively. We also found that exocrine cells were eliminated faster than endocrine cells, and beta-cells were lost at a higher rate than alpha-cells. Interestingly, one specific group of cells that have characteristics of immature alpha-cells or beta-cells, were enriched in LTC-islets, revealing the possibility of transdifferentiation of alpha-cells to beta-cells, or dedifferentiation of beta-cells to alpha-cells, under in vitro culture. Our results suggest that there are intrinsic cellular and molecular mechanisms in pancreatic cells that are associated with their maturity and correlated with their survival ability under unfavorable living conditions.

molecular biology↗

bioRxiv2022

Identification of a distinct ductal subpopulation with self-renewal and differentiation potential from the adult murine pancreas

Pancreatic ducts function to deliver digestive enzymes into the intestines. Upon injury, ducts can become proliferative and contribute to tissue regeneration; however, the identity of the ductal cells that contribute to these processes is unknown. We combined fluorescence-activated cell sorting, a methylcellulose-containing 3-dimensional culture, droplet RNA-sequencing, and a clonal lineage tracing tool to identify and isolate a distinct subpopulation of pancreatic ductal cells that exhibit progenitor cell properties. These ductal cells are unique in that they form tightly-bound clusters (termed FSCmid-high), with an average of 8 cells per cluster. FSCmid-high clusters comprise only about 0.1% of the total pancreas, are tri-potent for duct, acinar and endocrine lineages, and self-renew robustly in vitro. Transcriptomic analysis of FSCmid-high clusters reveals enrichment for genes involved in cell-cell interactions, organ development, and cancer pathways. FSCmid-high clusters express embryonic pancreatic progenitor markers Sox9, Pdx1, and Nkx6-1 at both transcription and protein levels. FSCmid-high clusters are resistant to enzymatic dissociation and survive severe in vivo acinar injury, which induces formation of ductal rosettes that become proliferative within 14 days. Thus, FSCmid-high clusters represent a small subset of ductal cells with progenitor cell properties. These rare progenitor-like duct cell clusters have implications in pancreas regeneration and tumor initiation/progression.

cell biology↗