METTL3 and obesity due to melanocortin 4 receptor deficiency: Evidence from APP/PS1, 5xFAD, tau transgenic, and Drosophila models demonstrates that regulators such as methyltransferase-like 3 and fat mass and obesity-associated protein influence Alzheimer's disease progression through neuroinflammation, circular RNAs dysregulation, and autophagy-related mechanisms.