Na⁺/Ca²⁺ Exchanger a Druggable Target to Promote β-Cell Proliferation and Function

Area of Science:

• Endocrinology
• Molecular Biology
• Cell Biology

Background:

• Type 2 diabetes is characterized by reduced beta-cell mass, necessitating strategies to enhance beta-cell proliferation.
• Previous studies demonstrated that heterozygous inactivation of the Na+/Ca2+ exchanger (NCX1) increases beta-cell proliferation, mass, and function in mice.

Purpose of the Study:

• To investigate the role of NCX1 in beta-cell proliferation in aged mice.
• To evaluate the efficacy of small molecules targeting NCX1 for stimulating beta-cell proliferation in vitro and in vivo.
• To elucidate the molecular mechanisms underlying NCX1 inhibition-induced beta-cell proliferation and survival.

Main Methods:

• Genetic inactivation of Ncx1 in aged mice.
• Treatment of adult mice and insulin-producing cells with NCX1 inhibitors (small molecules and small interfering RNA).
• Analysis of beta-cell proliferation, apoptosis, gene expression (Ins1, Ins2, Pdx1), and signaling pathways (calcineurin/NFAT).
• Assessment of tumor suppressor and cell cycle inhibitor activity (pRb, miR-193a, p53).

Main Results:

• NCX1 inactivation increased beta-cell proliferation in 2-year-old mice.
• Benzoxyphenyl-family small molecules targeting NCX1 stimulated beta-cell proliferation both in vitro and in vivo.
• NCX1 inhibition activated the calcineurin/NFAT pathway and reduced apoptosis induced by immunosuppressors.
• NCX1 inhibition upregulated beta-cell-specific genes and downregulated tumor suppressors and cell cycle inhibitors.

Conclusions:

• Na+/Ca2+ exchange is a druggable target for stimulating beta-cell function and proliferation.
• Specific beta-cell inhibition of NCX1 using phenoxybenzamyl derivatives offers a novel approach for beta-cell regeneration in diabetes.
• This strategy may enhance the efficacy of pancreatic islet transplantation for diabetes treatment.