We seek to understand the regulatory mechanisms that control the movements of mitochondria in cells. A protein complex that includes milton, Miro, and the kinesin-1 heavy chain (KHC) is essential for mitochondrial transport in neurons. Miro resides at the central hub to allow multiple cellular signals to control mitochondrial motility. These signals include mitophagy, calcium, hypoxia, and nutrient availability etc. Additionally, and most relevant to this proposal, we have obtained exciting preliminary results demonstrating that a novel machinery spanning both the mitochondrial outer and inner membranes–the mitochondrial intermembrane space bridging (MIB) complex, stabilizes Miro and regulates mitochondrial motility. This new discovery and our past work raise a burning question at the intersection of fundamental cell biology and neurobiology: How these discrete Miro-pathways functionally coordinate or converge on mitochondrial integrity in response to various stimuli and stresses? In this proposal, we will probe these questions using classical cell biological and neurobiological approaches combined with a powerful genetic tool (fruit flies) for functional validation. Aim 1: To dissect the functional significance of the MIB-Miro complex. Aim 2: To determine the nature of Miro interaction with its binding partners. Aim 3: To explore the interplay of the regulatory signals and machineries of Miro.