Limits...
HB-GAM (pleiotrophin) reverses inhibition of neural regeneration by the CNS extracellular matrix

View Article: PubMed Central - PubMed

ABSTRACT

Chondroitin sulfate (CS) glycosaminoglycans inhibit regeneration in the adult central nervous system (CNS). We report here that HB-GAM (heparin-binding growth-associated molecule; also known as pleiotrophin), a CS-binding protein expressed at high levels in the developing CNS, reverses the role of the CS chains in neurite growth of CNS neurons in vitro from inhibition to activation. The CS-bound HB-GAM promotes neurite growth through binding to the cell surface proteoglycan glypican-2; furthermore, HB-GAM abrogates the CS ligand binding to the inhibitory receptor PTPσ (protein tyrosine phosphatase sigma). Our in vivo studies using two-photon imaging of CNS injuries support the in vitro studies and show that HB-GAM increases dendrite regeneration in the adult cerebral cortex and axonal regeneration in the adult spinal cord. Our findings may enable the development of novel therapies for CNS injuries.

No MeSH data available.


HB-GAM turns the CSPG aggrecan to a potent activator of neurite growth.(a–c) Neurite outgrowth in cortical neurons on substrates coated with aggrecan (AGG), aggrecan + IgG or aggrecan + HB-GAM. Neurons display poor attachment and no neurite growth on aggrecan (10 μg/ml) or aggrecan + IgG (both at 10 μg/ml)-precoated substrate. (c,d) In contrast, HB-GAM precoated together with aggrecan (both at 10 μg/ml) induces neurite growth (150–200 μm/neuron) compared to unprecoated plastic, aggrecan or aggrecan + IgG. (c,e) HB-GAM (10 μg/ml) added to the culture medium induces robust neurite outgrowth on the substrate coated with aggrecan but even inhibits neurite outgrowth on uncoated substrate. The scale bar in a (20 μm) is valid for (a,b,d,e). Error bars represent standard error of mean (SEM), symbols *, ** and *** represent P < 0.05, 0.01 and 0.001, respectively. All data are based on 3 independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037378&req=5

f1: HB-GAM turns the CSPG aggrecan to a potent activator of neurite growth.(a–c) Neurite outgrowth in cortical neurons on substrates coated with aggrecan (AGG), aggrecan + IgG or aggrecan + HB-GAM. Neurons display poor attachment and no neurite growth on aggrecan (10 μg/ml) or aggrecan + IgG (both at 10 μg/ml)-precoated substrate. (c,d) In contrast, HB-GAM precoated together with aggrecan (both at 10 μg/ml) induces neurite growth (150–200 μm/neuron) compared to unprecoated plastic, aggrecan or aggrecan + IgG. (c,e) HB-GAM (10 μg/ml) added to the culture medium induces robust neurite outgrowth on the substrate coated with aggrecan but even inhibits neurite outgrowth on uncoated substrate. The scale bar in a (20 μm) is valid for (a,b,d,e). Error bars represent standard error of mean (SEM), symbols *, ** and *** represent P < 0.05, 0.01 and 0.001, respectively. All data are based on 3 independent experiments.

Mentions: We first studied the effect of HB-GAM on neurite growth from primary CNS neurons plated on aggrecan, a major CSPG in the CNS17. As expected, the aggrecan matrix effectively prevented neurite outgrowth from the CNS neurons (Fig. 1a–c). Coating of HB-GAM together with aggrecan overcame the inhibitory effect (Fig. 1c,d). Moreover, delayed addition of HB-GAM to culture media promoted neurite extension from the primary CNS neurons already inhibited by aggrecan (Supplementary Fig. S1).


HB-GAM (pleiotrophin) reverses inhibition of neural regeneration by the CNS extracellular matrix
HB-GAM turns the CSPG aggrecan to a potent activator of neurite growth.(a–c) Neurite outgrowth in cortical neurons on substrates coated with aggrecan (AGG), aggrecan + IgG or aggrecan + HB-GAM. Neurons display poor attachment and no neurite growth on aggrecan (10 μg/ml) or aggrecan + IgG (both at 10 μg/ml)-precoated substrate. (c,d) In contrast, HB-GAM precoated together with aggrecan (both at 10 μg/ml) induces neurite growth (150–200 μm/neuron) compared to unprecoated plastic, aggrecan or aggrecan + IgG. (c,e) HB-GAM (10 μg/ml) added to the culture medium induces robust neurite outgrowth on the substrate coated with aggrecan but even inhibits neurite outgrowth on uncoated substrate. The scale bar in a (20 μm) is valid for (a,b,d,e). Error bars represent standard error of mean (SEM), symbols *, ** and *** represent P < 0.05, 0.01 and 0.001, respectively. All data are based on 3 independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037378&req=5

f1: HB-GAM turns the CSPG aggrecan to a potent activator of neurite growth.(a–c) Neurite outgrowth in cortical neurons on substrates coated with aggrecan (AGG), aggrecan + IgG or aggrecan + HB-GAM. Neurons display poor attachment and no neurite growth on aggrecan (10 μg/ml) or aggrecan + IgG (both at 10 μg/ml)-precoated substrate. (c,d) In contrast, HB-GAM precoated together with aggrecan (both at 10 μg/ml) induces neurite growth (150–200 μm/neuron) compared to unprecoated plastic, aggrecan or aggrecan + IgG. (c,e) HB-GAM (10 μg/ml) added to the culture medium induces robust neurite outgrowth on the substrate coated with aggrecan but even inhibits neurite outgrowth on uncoated substrate. The scale bar in a (20 μm) is valid for (a,b,d,e). Error bars represent standard error of mean (SEM), symbols *, ** and *** represent P < 0.05, 0.01 and 0.001, respectively. All data are based on 3 independent experiments.
Mentions: We first studied the effect of HB-GAM on neurite growth from primary CNS neurons plated on aggrecan, a major CSPG in the CNS17. As expected, the aggrecan matrix effectively prevented neurite outgrowth from the CNS neurons (Fig. 1a–c). Coating of HB-GAM together with aggrecan overcame the inhibitory effect (Fig. 1c,d). Moreover, delayed addition of HB-GAM to culture media promoted neurite extension from the primary CNS neurons already inhibited by aggrecan (Supplementary Fig. S1).

View Article: PubMed Central - PubMed

ABSTRACT

Chondroitin sulfate (CS) glycosaminoglycans inhibit regeneration in the adult central nervous system (CNS). We report here that HB-GAM (heparin-binding growth-associated molecule; also known as pleiotrophin), a CS-binding protein expressed at high levels in the developing CNS, reverses the role of the CS chains in neurite growth of CNS neurons in vitro from inhibition to activation. The CS-bound HB-GAM promotes neurite growth through binding to the cell surface proteoglycan glypican-2; furthermore, HB-GAM abrogates the CS ligand binding to the inhibitory receptor PTP&sigma; (protein tyrosine phosphatase sigma). Our in vivo studies using two-photon imaging of CNS injuries support the in vitro studies and show that HB-GAM increases dendrite regeneration in the adult cerebral cortex and axonal regeneration in the adult spinal cord. Our findings may enable the development of novel therapies for CNS injuries.

No MeSH data available.