Sequential in vivo labeling of insulin secretory granule pools in INS-SNAP transgenic pigs

The failure of β cells to secrete sufficient amounts of insulin is a key feature of diabetes mellitus. Each β cell secretes only a small amount of insulin upon stimulation in a highly regulated fashion: young insulin is preferentially released, whereas old insulin is mainly degraded within the β cell. How this process is regulated in vivo and likely altered in diabetes is currently unknown. We present here a transgenic pig model that allows the in vivo fluorescent labeling of age-distinct insulin secretory granule pools, hence providing a close-to-life readout of insulin turnover. This will enable the study of alterations in β cell function in an animal model close to humans