Mitochondrial transfer mediates metabolic communication between beta cells and islet macrophages

Pancreatic islet macrophages play a crucial role in maintaining islet homeostasis and adjusting their metabolic functions based on external signals. Among these signals are factors released by beta cells, which are known for their robust secretory activity. To investigate whether beta cells can transfer mitochondria to these macrophages, researchers created mice with beta cell-specific expression of mitochondrial green fluorescent protein (PhAMfloxIns1Cre).

The study revealed that beta cells do indeed transfer mitochondria to islet macrophages both in live animals and in laboratory conditions.

The transfer of mitochondria from beta cells to macrophages was observed in both scenarios, confirming the biological process. However, diabetogenic stressors did not impact the frequency of mitochondrial transfer, indicating that this mechanism operates independently of stress. Macrophages containing mitochondria derived from beta cells showed higher protein synthesis rates compared to those without the mitochondrial transfer.

Genetic analysis using RNA sequencing showed that macrophages receiving mitochondria from beta cells upregulated the expression of activity-regulated cytoskeleton associated protein (Arc). This protein is involved in cytoskeleton dynamics, which are crucial for the transfer process.

Interestingly, disrupting the actin cytoskeleton in macrophages prevented the mitochondrial transfer, suggesting a direct link between cytoskeleton structure and the process. These findings present mitochondrial transfer as a novel mechanism through which beta cells and islet macrophages communicate. This communication could potentially contribute to the maintenance of islet homeostasis and immune regulation within the pancreas.