ALDH3B2 inactivation shifted human pancreatic duct cells toward a β-like state in experiments using human cells and mice
ALDH3B2 inactivation shifted human pancreatic duct cells toward a β-like state in experiments using human cells and mice
On 2 September, Science Translational Medicine published a study describing how inactivation of a single gene changed a subset of the cells lining pancreatic ducts. When these cells were transplanted into diabetic mice, blood glucose was lower than in animals that received control cells.
Pancreatic β-cells secrete insulin, the hormone that regulates blood glucose. In diabetes, these cells are either too few or do not function adequately. Researchers are therefore trying to restore their function with donor islets and cells derived from stem cells. The authors investigated another potential source: the cells lining the ducts through which the pancreas releases digestive fluid.
To identify a gene that maintains these cells in their original state, the researchers conducted a genome-wide CRISPR screen. They inactivated different genes one at a time and selected cells in which the insulin gene became active. For this large-scale screen, they used the PANC-1 pancreatic duct cell line, which can be grown in large quantities. Among eight candidates, ALDH3B2 inactivation produced the highest insulin gene activity and the lowest KRT19 gene activity in this cell line. KRT19 is a marker of ductal cells.
The researchers then inactivated ALDH3B2 in purified primary human duct cells. These cells showed increased activity of β-cell genes and developed insulin-containing granules. An increase in glucose also triggered the secretion of human insulin. Modified cells or control cells were transplanted beneath the outer capsule of the kidney in two groups of five diabetic mice. Blood glucose was lower in the animals that received the modified cells. On day 56, after the graft was removed, blood glucose returned to the level observed in the control group. Human insulin was also detected in the blood after glucose administration.
Single-cell analysis, which measures gene activity separately in each cell, showed the extent of the transition. The insulin gene was active in 18.1% of cells with inactivated ALDH3B2 and in 0.6% of control cells. KRT19 remained active in approximately 93% of cells in both groups, indicating that they retained a ductal identity. The resulting β-like population was heterogeneous, with some cells showing features of both ductal cells and β-cells. ALDH3B2 therefore provides a genetic target for further study of whether cells already present in the pancreas can be directed to replace lost function.