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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 HSCs after BDNF treatment. BDNF (100 pM) was administered to treat the human Schwann cells at 0 min, 10 min, 30 min, 60 min, 120 min, 24 hr and 72 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 60 min (lane 4) (*P<0.01). In human Schwann cells, STAT3/STAT1 phosphorylation sustained for a relatively longer response period than in rat Schwann cells. Two hours later, the pSTAT1 returned to near baseline level (lane 5), while the pSTAT3 remained at a higher than baseline level. In addition, STAT3/STAT1 regained phosphorylation and reached a second peak at 24–48 hr (lane 6&7) (#P<0.01). The activation of STAT1 was totally quenched at 72 hr post-BDNF treatment (lane 8), while pSTAT3 remained at a higher than baseline level also. (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in HSCs. Three independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; HSCs, human Schwann cells; BDNF, brain-derived neurotrophic factor.
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f3: Time response of JAK/STAT pathway activation in HSCs after BDNF treatment. BDNF (100 pM) was administered to treat the human Schwann cells at 0 min, 10 min, 30 min, 60 min, 120 min, 24 hr and 72 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 60 min (lane 4) (*P<0.01). In human Schwann cells, STAT3/STAT1 phosphorylation sustained for a relatively longer response period than in rat Schwann cells. Two hours later, the pSTAT1 returned to near baseline level (lane 5), while the pSTAT3 remained at a higher than baseline level. In addition, STAT3/STAT1 regained phosphorylation and reached a second peak at 24–48 hr (lane 6&7) (#P<0.01). The activation of STAT1 was totally quenched at 72 hr post-BDNF treatment (lane 8), while pSTAT3 remained at a higher than baseline level also. (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in HSCs. Three independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; HSCs, human Schwann cells; BDNF, brain-derived neurotrophic factor.

Mentions: Since HSCs share the same biological properties with RSCs, we repeated the experiment in HSCs. To observe the sustained time frame of the second activation of JAK/STAT pathway, another time point (72 hr) was added. Similar to RSCs RT4-D6P2T, the initial activation time for STAT3/STAT1 was 10 min after the treatment of BDNF. However, in HSCs, STAT3/STAT1 phosphorylation was sustained for a relatively longer response period, and the phosphorylation level peaks appeared later, at 60 min. Two hours later, the pSTAT1 returned to near baseline, while pSTAT3 remained at higher than baseline level. Interestingly, STAT3/STAT1 phosphorylation also peaked again at 24–48 hr. The activation of STAT1 was totally quenched at 72 hr post-BDNF treatment, while pSTAT3 remained at a higher level than baseline (Figure 3).


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 HSCs after BDNF treatment. BDNF (100 pM) was administered to treat the human Schwann cells at 0 min, 10 min, 30 min, 60 min, 120 min, 24 hr and 72 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 60 min (lane 4) (*P<0.01). In human Schwann cells, STAT3/STAT1 phosphorylation sustained for a relatively longer response period than in rat Schwann cells. Two hours later, the pSTAT1 returned to near baseline level (lane 5), while the pSTAT3 remained at a higher than baseline level. In addition, STAT3/STAT1 regained phosphorylation and reached a second peak at 24–48 hr (lane 6&7) (#P<0.01). The activation of STAT1 was totally quenched at 72 hr post-BDNF treatment (lane 8), while pSTAT3 remained at a higher than baseline level also. (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in HSCs. Three independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; HSCs, human Schwann cells; BDNF, brain-derived neurotrophic factor.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4837308&req=5

f3: Time response of JAK/STAT pathway activation in HSCs after BDNF treatment. BDNF (100 pM) was administered to treat the human Schwann cells at 0 min, 10 min, 30 min, 60 min, 120 min, 24 hr and 72 hr. STAT3/STAT1 were activated at 10 min after the treatment with BDNF (lane 2), and the phosphorylation level peaked at 60 min (lane 4) (*P<0.01). In human Schwann cells, STAT3/STAT1 phosphorylation sustained for a relatively longer response period than in rat Schwann cells. Two hours later, the pSTAT1 returned to near baseline level (lane 5), while the pSTAT3 remained at a higher than baseline level. In addition, STAT3/STAT1 regained phosphorylation and reached a second peak at 24–48 hr (lane 6&7) (#P<0.01). The activation of STAT1 was totally quenched at 72 hr post-BDNF treatment (lane 8), while pSTAT3 remained at a higher than baseline level also. (A) Panel represents western blotting and (B) panel represents the phosphorylation ratio of STAT1 and STAT3 in HSCs. Three independent experiments were done for each data point, and the error bars represent ± SD. JAK, Janus kinase; STAT, signal transducer and activator of transcription; HSCs, human Schwann cells; BDNF, brain-derived neurotrophic factor.
Mentions: Since HSCs share the same biological properties with RSCs, we repeated the experiment in HSCs. To observe the sustained time frame of the second activation of JAK/STAT pathway, another time point (72 hr) was added. Similar to RSCs RT4-D6P2T, the initial activation time for STAT3/STAT1 was 10 min after the treatment of BDNF. However, in HSCs, STAT3/STAT1 phosphorylation was sustained for a relatively longer response period, and the phosphorylation level peaks appeared later, at 60 min. Two hours later, the pSTAT1 returned to near baseline, while pSTAT3 remained at higher than baseline level. Interestingly, STAT3/STAT1 phosphorylation also peaked again at 24–48 hr. The activation of STAT1 was totally quenched at 72 hr post-BDNF treatment, while pSTAT3 remained at a higher level than baseline (Figure 3).

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