The Journal of Neuroscience, September 1, 2002, 22(17):7493-7501
Dynamic Pattern of Reg-2 Expression in Rat Sensory Neurons after
Peripheral Nerve Injury
Sharon
Averill1, *,
Danny R.
Davis2, *,
Peter J.
Shortland1,
John V.
Priestley1, and
Stephen P.
Hunt2
1 Department of Neuroscience, Queen Mary University of
London, London, E1 4NS, United Kingdom, and 2 Department of
Anatomy and Developmental Biology, University College London, London,
WC1E 6BT, United Kingdom
The 16 kDa pancreatitis-associated protein Reg-2 has recently been
shown to facilitate the regeneration of motor and sensory neurons after
peripheral nerve injury in the adult rat. Reg-2 has also been shown to
be a neurotrophic factor that is an essential intermediate in the
pathways through which CNTF supports the survival of motor neurons
during development. Here we report the dynamic expression of Reg-2 in
rat sensory neurons after peripheral nerve injury. Reg-2 is normally
not expressed by dorsal root ganglion (DRG) cells, but we show, using
immunocytochemistry, that Reg-2 is rapidly upregulated in DRG cells
after sciatic nerve transection and after 24 hr recovery is expressed
almost exclusively in small-diameter neurons that bind the
lectin Griffonia simplicifolia IB4 and express the
purinoceptor P2X3. However, by 7 d after axotomy,
Reg-2 is expressed in medium to large neurons and coexists partly with the neuropeptides galanin and neuropeptide Y, which are also
upregulated after peripheral nerve transection. At this time point,
Reg-2 is no longer expressed in small neurons, and there is no
colocalization with IB4 binding neurons, demonstrating a shift in Reg-2
expression from one subset of DRG neurons to another. We also show by
double labeling for activating transcription factor 3, a
transcription factor that is upregulated after nerve injury, that Reg-2
expression occurs predominantly in axotomized DRG cells but that a
small percentage of uninjured DRG cells also upregulate Reg-2. The
selective expression within IB4/P2X3 cells, and the dynamic
shift from small to large cells, is unique among DRG peptides and
suggests that Reg-2 has a distinctive role in the injury response.
Key words:
regeneration; axotomy; dorsal root ganglia; neuropeptide; peripheral nerve injury; Reg-2
*
S.A. and D.R.D. contributed equally to this study.