ABSTRACT
Fidgetin-like 2 (FL2) is a microtubule (MT) regulatory protein that modulates MT dynamics through its putative
MT-severing activity, regulating cell motility and axonal growth and guidance. Recently, we identified FL2 as a
negative regulator of axonal growth, and demonstrated that targeted depletion of FL2 following peripheral nerve
injury enhances functional nerve regeneration in rats. Our preliminary studies show that following injury FL2 is
upregulated at the injury site in several adult tissues including the spinal cord. In pilot studies using rodent SCI
models, we similarly found that local depletion of FL2 from the injury site using FL2 siRNA embedded in
nanoparticles (SiFi2) improved recovery of locomotor and bladder function after thoracic contusion and
compression injury. We hypothesize that FL2 negatively regulates axonal regeneration after SCI, and that
downregulation of FL2 after SCI will improve functional recovery. We aim to test this hypothesis with 3 specific
aims. The first aim will determine the extent and duration of FL2 silencing following SiFi2 treatment. The second
aim will evaluate the functional effects of SiFi2 treatment after SCI by exploring hindlimb locomotor and sensory
function after SiFi2 administration. The third aim will evaluate molecular and histological changes at the spinal
cord lesion site following SiFi2 treatment by examining axonal regeneration, glial scar formation, and
inflammatory response in the spinal cord tissue from Aim 2. These studies will be the first to evaluate FL2
regulation of the central nervous system (CNS) injury response, and the first to assess the therapeutic potential
of using RNAi to transiently downregulate FL2 expression in order to improve functional recovery after CNS
injury. While this proposal focuses specifically on SCI as a therapeutic application, we anticipate the data
generated from these studies will have broader implications as they will characterize the role of a previously
unstudied regulator of CNS traumatic injury response, one which can potentially be targeted to enhance
regeneration following a wide range of CNS injuries.
