Sunday Driver/JIP3 binds kinesin heavy chain directly and enhances its motility

Abstract

Neuronal development, function and repair critically depend on axonal transport of vesicles and protein complexes, which is mediated in part by the molecular motor kinesin-1. Adaptor proteins recruit kinesin-1 to vesicles via direct association with kinesin heavy chain (KHC), the force-generating component, or via the accessory light chain (KLC). Binding of adaptors to the motor is believed to engage the motor for microtubule-based transport. We report that the adaptor protein Sunday Driver (syd, also known as JIP3 or JSAP1) interacts directly with KHC, in addition to and independently of its known interaction with KLC. Using an in vitro motility assay, we show that syd activates KHC for transport and enhances its motility, increasing both KHC velocity and run length. syd binding to KHC is functional in neurons, as syd mutants that bind KHC but not KLC are transported to axons and dendrites similarly to wild-type syd. This transport does not rely on syd oligomerization with itself or other JIP family members. These results establish syd as a positive regulator of kinesin activity and motility.

c-Jun NH2-terminal Kinase (JNK)-interacting Protein-3 (JIP3) Regulates Neuronal Axon Elongation in a Kinesin- and JNK-dependent Manner

“…1C). Previous reports have shown that JIP3 concentrates in the axon tips (6,26). Our results extend this finding by examining the stages of hippocampal process outgrowth.…”

“…Interestingly, JIP3 is selectively expressed in the embryonic and adult mouse brains (3,4). Furthermore, the expression of JIP3 is predominantly localized in the cell bodies and axons of developing neurons and concentrates at axon tips in cultured hippocampal neurons (5,6). Together, these studies prompt the hypothesis that JIP3 might regulate axon development.…”

“…As a member of the JIPs, JIP3 has been suggested to tether specific JNK signaling modules, thereby promoting signal transmission (3)(4)(5)(6). The JNK pathway is involved in axon formation/polarization, extension, synaptic plasticity, and dendrite development (7)(8)(9)(10)(11).…”

JSAP1/JIP3 and JLP regulate kinesin-1-dependent axonal transport to prevent neuronal degeneration

“…JSAP1 and JLP may also increase kinesin-1 motor activity by enhancing kinesin-1-MT binding. Indeed, using an in vitro motility assay, Sun et al 26 showed that JSAP1 binding to KHC enhances KHC's motility along MTs. We found that the kinesin-1-MT binding was reduced in AxCANCre-infected Jsap1:Jlp dKO neurons at 3 d.p.i.…”

“…26 We used lentiviral vectors to express these wild-type and mutant JSAP1 forms as hemagglutinin (HA)-tagged proteins (designated HA-JSAP1-WT, -LZ and -ΔKBD) in primary hippocampal neurons. Although HA-JSAP1-WT, -LZ and -ΔKBD were widely distributed along the axons, double-mutant HA-JSAP1-LZ/ΔKBD failed to exit the cell body, as reported previously 26 (Figure 5a). We next conducted a time-lapse study using Jsap1:Jlp dKO neurons infected with the various HA-JSAP1 lentiviral constructs.…”