A role for Hydroxy-Acyl Coenzyme A dehydrogenase (HADH) in insulin secretion and type 2 diabetes development

The Hydroxy-Acyl Coenzyme-A Dehydrogenase (HADH) gene encodes the 3-hydroxyacyl-CoA dehydrogenase enzyme, which participates in mitochondrial β-oxidation of fatty acids, thereby regulating cellular functions. Loss-of-function mutations affecting HADH activity in pancreatic islets and adipose tissue have been linked to Hyperinsulinemic Hypoglycaemia (HH), a rare cause of Congenital Hyperinsulinism of Infancy (CHI). Dysregulation and accumulation of metabolic intermediates like 3-hydroxyacyl-CoAs can cause mitochondrial stress and impair insulin release, potentially leading to life-threatening hypoglycaemia. This study investigates the role of HADH in β-cell function, insulin secretion, and mitochondrial metabolism, aiming to determine whether modified HADH expression contributes to β-cell dysfunction in type 2 diabetes (T2D). Using a clonal rat-derive β-cell line (INS-1 832/13) with silenced gene expression via small interfering (si) RNAs, changes in β-cell function were assessed by quantitative (q) polymerase chain reaction (PCR), insulin secretion assays, e.g. glucose-stimulated insulin secretion (GSIS), enzyme-linked immunosorbent assay (ELISA), bicinchoninic acid assay (BCA), and Western blot. Results revealed successful siRNA-mediated knockdown of HADH at both mRNA (p=0.0020) and protein level (p=0.0168). Contrary to expectations and prior data, no significant difference in insulin release under varying metabolic conditions following GSIS (p=0.9295) was observed, likely due to experimental errors and limited cell response. Overall, despite the validation of the knockdown techniques used, future studies are needed to clarify the effects of HADH in insulin secretion and other β-cell responses, providing a deeper insight into its link to metabolic diseases.