Figure 6.

Increasing fusion chronically, either genetically or pharmacologically, alters RGC growth cone responses to both inhibitory and to permissive guidance cues. A. RGCs normally turn and fail to cross chondroitin sulfate proteoglycan (CSPG) borders (green). B. Overexpressing Mfn2 or treating RGCs with Mdivi-1 (not shown) prior to axon initiation permits RGC growth cones to cross CSPG stripes without altering neurite growth rate (not shown). B. Schematic of increasing fusion on RGC axon decision-making. Untreated RGCs, turn and grow along CSPG stripes whereas Mfn2 overexpressing or DRP-1 inhibited RGC axons cross CSPG stripes. Inhibiting DRP-1 with Mdivi-1 also alters RGC responses to permissive cues netrin-1 and fibronectin by decreasing crossing from netrin-1 and fibronectin onto laminin [43]. Bar is 10 μm. C. Summary: Increasing fusion by either inhibiting DRP-1 mediated fission or increasing fusion by overexpressing Mfn2 alters growth cone decision making.