Defective cytoplasmic granule formation

Abstract 

We investigated the development of secretory granules in the pancreatic acinar cells of normal (C57BL/6J +/+) and beige (C57BL/6J Lyst ^bg /Lyst ^bg) mice by analyzing the distribution of ³H label in pancreatic acinar cells after a pulse of [³H]glycine administered in vivo. The results provide quantitative confirmation of the hypothesis that the maturation of condensing vacuoles/immature granules to mature granules in pancreatic acinar cells is associated with a significant volume reduction. Beige mice differ from control mice by exhibiting a more rapid distribution of ³H label from the rough endoplasmic reticulum-rich cytoplasm to the secretory granules and a slightly faster rate of maturation of ³H-labeled granules. Beige mouse pancreatic acinar cells also exhibited, as early as 1 h after pulsing with [³H]glycine, a much higher proportion of ³H-labeled secretory granules than did the cells of control mice. These findings identify additional abnormalities in secretory granule formation in pancreatic acinar cells which are related to the beige (Lyst ^bg) mutation and provide support for the hypothesis that beige mice exhibit an abnormal pattern of granule-granule fusion.