Overview of previous research

1. Insulin biosynthesis and secretion

Diabetes mellitus is a chronic hyperglycemic condition in which blood sugar is not taken up by tissues due to deficiency or reduced action of insulin. Insulin biosynthesis and secretion in pancreatic β cells, which are insulin-producing cells, is a central problem of β cell biology. We are studying glucose-stimulated insulin biosynthesis and secretion, focusing on the CD38-cyclic ADP-ribose-ryanodine receptor-Ca2+ signaling system discovered in our laboratory.

2. Death and regeneration of insulin-producing cells

Pancreatic β cells, which are insulin-producing cells, are damaged by immune abnormalities and various radicals, leading to their death. Therefore, their regeneration would be expected to contribute to a fundamental cure for diabetes. We are studying the “Reg (regenerating gene) protein/Reg receptor signaling system” in which Reg proteins act on receptors as cell growth factors to explore the possibility of tissue regeneration.

3. Molecular biology of intermittent hypoxia

Sleep apnea syndrome (SAS), which is characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]), is a risk factor for lifestyle diseases such as diabetes, obesity, hypertension, and atherosclerosis. We are attempting to elucidate the effects of IH on the complications of lifestyle diseases from a molecular biological perspective. We have found that IH causes impaired function and compensatory proliferation of pancreatic β cells, increased expression of hepatokines in hepatocytes, increased expression of adipokines in adipocytes, and increased expression of myokines in skeletal muscle cells, which may increase the susceptibility to complications of type 2 diabetes.