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Brain-derived neurotrophic factor promotes nerve regeneration by activating the JAK/STAT pathway in Schwann cells.

Lin G, Zhang H, Sun F, Lu Z, Reed-Maldonado A, Lee YC, Wang G, Banie L, Lue TF - Transl Androl Urol (2016)

Bottom Line: We hypothesize that brain-derived neurotrophic factor (BDNF) activates the Janus kinase (JAK)/(signal transducer and activator of transcription) STAT pathway in Schwann cells, not in neuronal axonal fibers, with the resultant secretion of cytokines from Schwann cells to facilitate nerve recovery.We demonstrated for the first time the indirect mechanism of BDNF enhancement of nerve regeneration through the activation of JAK/STAT pathway in Schwann cells, rather than directly on neurons.As a result of BDNF application, Schwann cells produce cytokines that promote nerve regeneration.

View Article: PubMed Central - PubMed

Affiliation: 1 Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, CA, USA ; 2 Minimally Invasive Urology Center, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250012, China ; 3 Department of Urology, The First Hospital of Jilin University, Changchun 130021, China ; 4 Department of Urology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.

ABSTRACT

Background: Radical prostatectomy (RP) carries the risk of erectile dysfunction (ED) due to cavernous nerve (CN) injury. Schwann cells are essential for the maintenance of integrity and function of peripheral nerves such as the CNs. We hypothesize that brain-derived neurotrophic factor (BDNF) activates the Janus kinase (JAK)/(signal transducer and activator of transcription) STAT pathway in Schwann cells, not in neuronal axonal fibers, with the resultant secretion of cytokines from Schwann cells to facilitate nerve recovery.

Methods: Using four different cell lines-human neuroblastoma BE(2)-C and SH-SY5Y, human Schwann cell (HSC), and rat Schwann cell (RSC) RT4-D6P2T-we assessed the effect of BDNF application on the activation of the JAK/STAT pathway. We also assessed the time response of JAK/STAT pathway activation in RSCs and HSCs after BDNF treatment. We then assayed cytokine release from HSCs as a response to BDNF treatment using oncostatin M and IL6 as markers.

Results: We showed extensive phosphorylation of STAT3/STAT1 by BDNF at high dose (100 pM) in RSCs, with no JAK/STAT pathway activation in human neuroblastoma cell lines. The time response of JAK/STAT pathway activation in RSCs and HSCs after BDNF treatment showed an initial peak at shortly after treatment and then a second higher peak at 24-48 hours. Cytokine release from HSCs increased progressively after BDNF application, reaching statistical significance for IL6.

Conclusions: We demonstrated for the first time the indirect mechanism of BDNF enhancement of nerve regeneration through the activation of JAK/STAT pathway in Schwann cells, rather than directly on neurons. As a result of BDNF application, Schwann cells produce cytokines that promote nerve regeneration.

No MeSH data available.


Related in: MedlinePlus

Time response of JAK/STAT pathway activation in RT4-D6P2T after BDNF administration. BDNF (100 pM) was administered to treat rat Schwann cells RT4-D6P2T at 0 min, 10 min, 30 min, 60 min, 120 min and 24 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 30 min (lane 3) (*P<0.01). One hour later, the pSTAT3/pSTAT1 returned to baseline level (lane 4). Interestingly, STAT3/STAT1 regained phosphorylation at 2 hr post BDNF treatment (lane 5) and reached a second peak at 24 hr, which was even higher than the first peak (lane 6) (#P<0.01). (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in RT4-D6P2T. Four independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; BDNF, brain-derived neurotrophic factor.
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f2: Time response of JAK/STAT pathway activation in RT4-D6P2T after BDNF administration. BDNF (100 pM) was administered to treat rat Schwann cells RT4-D6P2T at 0 min, 10 min, 30 min, 60 min, 120 min and 24 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 30 min (lane 3) (*P<0.01). One hour later, the pSTAT3/pSTAT1 returned to baseline level (lane 4). Interestingly, STAT3/STAT1 regained phosphorylation at 2 hr post BDNF treatment (lane 5) and reached a second peak at 24 hr, which was even higher than the first peak (lane 6) (#P<0.01). (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in RT4-D6P2T. Four independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; BDNF, brain-derived neurotrophic factor.

Mentions: To explore the detailed response of JAK/STAT to BDNF, time response was checked in the RT4-D6P2T cells. One hundred pM BDNF was administered to treat the RSCs at different times, including 0 min, 10 min, 30 min, 60 min, 120 min and 24 hr. The phosphorylation levels of STAT3 at Tyr705 and STAT1 at Tyr701 began to increase 10 min after the treatment with BDNF and peaked at 30 min (*P<0.01). After reaching its peak, the pSTAT3/pSTAT1 returned to near baseline. Surprisingly, STAT3 and STAT1 regained phosphorylation at 2 hr post-treatment by BDNF and reached a second peak at 24 hr, which was even higher than the first one (#P<0.01). The second round activation may relate to mechanisms other than the direct effect of BDNF (Figure 2).


Brain-derived neurotrophic factor promotes nerve regeneration by activating the JAK/STAT pathway in Schwann cells.

Lin G, Zhang H, Sun F, Lu Z, Reed-Maldonado A, Lee YC, Wang G, Banie L, Lue TF - Transl Androl Urol (2016)

Time response of JAK/STAT pathway activation in RT4-D6P2T after BDNF administration. BDNF (100 pM) was administered to treat rat Schwann cells RT4-D6P2T at 0 min, 10 min, 30 min, 60 min, 120 min and 24 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 30 min (lane 3) (*P<0.01). One hour later, the pSTAT3/pSTAT1 returned to baseline level (lane 4). Interestingly, STAT3/STAT1 regained phosphorylation at 2 hr post BDNF treatment (lane 5) and reached a second peak at 24 hr, which was even higher than the first peak (lane 6) (#P<0.01). (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in RT4-D6P2T. Four independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; BDNF, brain-derived neurotrophic factor.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4837308&req=5

f2: Time response of JAK/STAT pathway activation in RT4-D6P2T after BDNF administration. BDNF (100 pM) was administered to treat rat Schwann cells RT4-D6P2T at 0 min, 10 min, 30 min, 60 min, 120 min and 24 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 30 min (lane 3) (*P<0.01). One hour later, the pSTAT3/pSTAT1 returned to baseline level (lane 4). Interestingly, STAT3/STAT1 regained phosphorylation at 2 hr post BDNF treatment (lane 5) and reached a second peak at 24 hr, which was even higher than the first peak (lane 6) (#P<0.01). (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in RT4-D6P2T. Four independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; BDNF, brain-derived neurotrophic factor.
Mentions: To explore the detailed response of JAK/STAT to BDNF, time response was checked in the RT4-D6P2T cells. One hundred pM BDNF was administered to treat the RSCs at different times, including 0 min, 10 min, 30 min, 60 min, 120 min and 24 hr. The phosphorylation levels of STAT3 at Tyr705 and STAT1 at Tyr701 began to increase 10 min after the treatment with BDNF and peaked at 30 min (*P<0.01). After reaching its peak, the pSTAT3/pSTAT1 returned to near baseline. Surprisingly, STAT3 and STAT1 regained phosphorylation at 2 hr post-treatment by BDNF and reached a second peak at 24 hr, which was even higher than the first one (#P<0.01). The second round activation may relate to mechanisms other than the direct effect of BDNF (Figure 2).

Bottom Line: We hypothesize that brain-derived neurotrophic factor (BDNF) activates the Janus kinase (JAK)/(signal transducer and activator of transcription) STAT pathway in Schwann cells, not in neuronal axonal fibers, with the resultant secretion of cytokines from Schwann cells to facilitate nerve recovery.We demonstrated for the first time the indirect mechanism of BDNF enhancement of nerve regeneration through the activation of JAK/STAT pathway in Schwann cells, rather than directly on neurons.As a result of BDNF application, Schwann cells produce cytokines that promote nerve regeneration.

View Article: PubMed Central - PubMed

Affiliation: 1 Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, CA, USA ; 2 Minimally Invasive Urology Center, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250012, China ; 3 Department of Urology, The First Hospital of Jilin University, Changchun 130021, China ; 4 Department of Urology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.

ABSTRACT

Background: Radical prostatectomy (RP) carries the risk of erectile dysfunction (ED) due to cavernous nerve (CN) injury. Schwann cells are essential for the maintenance of integrity and function of peripheral nerves such as the CNs. We hypothesize that brain-derived neurotrophic factor (BDNF) activates the Janus kinase (JAK)/(signal transducer and activator of transcription) STAT pathway in Schwann cells, not in neuronal axonal fibers, with the resultant secretion of cytokines from Schwann cells to facilitate nerve recovery.

Methods: Using four different cell lines-human neuroblastoma BE(2)-C and SH-SY5Y, human Schwann cell (HSC), and rat Schwann cell (RSC) RT4-D6P2T-we assessed the effect of BDNF application on the activation of the JAK/STAT pathway. We also assessed the time response of JAK/STAT pathway activation in RSCs and HSCs after BDNF treatment. We then assayed cytokine release from HSCs as a response to BDNF treatment using oncostatin M and IL6 as markers.

Results: We showed extensive phosphorylation of STAT3/STAT1 by BDNF at high dose (100 pM) in RSCs, with no JAK/STAT pathway activation in human neuroblastoma cell lines. The time response of JAK/STAT pathway activation in RSCs and HSCs after BDNF treatment showed an initial peak at shortly after treatment and then a second higher peak at 24-48 hours. Cytokine release from HSCs increased progressively after BDNF application, reaching statistical significance for IL6.

Conclusions: We demonstrated for the first time the indirect mechanism of BDNF enhancement of nerve regeneration through the activation of JAK/STAT pathway in Schwann cells, rather than directly on neurons. As a result of BDNF application, Schwann cells produce cytokines that promote nerve regeneration.

No MeSH data available.


Related in: MedlinePlus