UBC9-mediated SUMOylation of Lamin B1 enhances DNA-damage-induced nuclear DNA leakage and autophagy after spinal cord injury.

Recent studies have shown that nucleophagy can mitigate DNA damage by selectively degrading nuclear components protruding from the nucleus. However, little is known about the role of nucleophagy in neurons after spinal cord injury (SCI). Western blot analysis and immunofluorescence were performed to evaluate the nucleophagy after nuclear DNA damage and leakage in SCI neurons in vivo and NSC34 expression in primary neurons cultured with oxygen-glucose deprivation (OGD) in vitro, as well as the interaction and colocalization of autophagy protein LC3 with nuclear lamina protein Lamin B1. The effect of UBC9, a Small ubiquitin-related modifier (SUMO) E2 ligase, on Lamin B1 SUMOylation and nucleophagy was examined by siRNA transfection or 2-D08 (a small-molecule inhibitor of UBC9), immunoprecipitation, and immunofluorescence. In SCI and OGD injured NSC34 or primary cultured neurons, neuronal nuclear DNA damage induced the SUMOylation of Lamin B1, which was required by the nuclear Lamina accumulation of UBC9. Furthermore, LC3/Atg8, an autophagy-related protein, directly bound to SUMOylated Lamin B1, and delivered Lamin B1 to the lysosome. Knockdown or suppression of UBC9 with siRNA or 2-D08 inhibited SUMOylation of Lamin B1 and subsequent nucleophagy and protected against neuronal death. Upon neuronal DNA damage and leakage after SCI, SUMOylation of Lamin B1 is induced by nuclear Lamina accumulation of UBC9. Furthermore, it promotes LC3-Lamin B1 interaction to trigger nucleophagy that protects against neuronal DNA damage.

Forest gaps regulate seed germination rate and radicle growth of an endangered plant species in a subtropical natural forest.

The survival rate of Castanopsis kawakamii from seed to seedling is relatively low, leading to difficulties in the regeneration of its natural forests. Forest gaps play a vital role in plant regeneration and biodiversity maintenance in forest ecosystems. Unfortunately, our understanding of the effects of gap size and within-gap position on the seed germination and radicle growth of C. kawakamii is still limited. In particular, our knowledge on the relationship between gap size and environmental factors and their influence on seed germination and radicle growth is incomplete. In the present study, we studied the influences of forest gaps and within-gap position on seed regeneration on the germination and radicle growth of an endangered species C. kawakamii in a subtropical natural forest in China. We selected three large gaps (LG, gap size above 200 m2), three medium gaps (MG, gap size 50-100 m2), three small gaps (SG, gap size 30-50 m2), and non-gap (NG), and planted the seeds of C. kawakamii in five positions within each gap. The results showed that (1) the influence of forest gaps on seed germination rate was, from highest to lowest, medium gaps (51%), non-gap (47%), small gaps (40%) and large gaps (17%), and the seed germination rate was the highest in all positions in medium gaps, with the exception of the east position. (2) Radicle length in forest gaps was, from highest to lowest, medium gaps, small gaps, large gaps and non-gap, and it was the highest in the east, south, west and north positions of medium gaps. (3) Canopy openness (gap size) and air temperature were the main factors influencing seed germination and radicle growth of C. kawakamii. We concluded that medium-sized gaps were the most suitable for seed germination and radicle growth of C. kawakamii, and they promote the regeneration of this endangered species in the investigated natural forest.

[Clinical application of percutaneous transforaminal endoscope-assisted lumbar interbody fusion].

OBJECTIVE: To conclude of the technical notes of percutaneous transforaminal endoscope-assisted lumbar interbody fusion (PT-Endo-LIF), and to investigate its safety and efficacy for treatment of degenerative lumbar disease. METHODS: Twenty-four patients were treated by PT-Endo-LIF combined with posterior percutaneous pedicle screws fixation from October 2017 to April 2018. There were 16 males and 8 females, ranging in age from 39 to 72 years old, with a mean of (59.6±9.5) years old. There were 15 cases diagnosed with lumbar intervertebral disc herniation combined with degenerative disc, the other 9 cases were diagnosed as low level lumbar spondylolistheses w/o segmental instability. Single segmental fusion was performed for 22 cases(one for L2,3, 3 for L3,4 and 18 for L4,5) and 2 segmental fusion was performed for the other 2 cases (both for L3,4 and L4,5). PT-Endo-LIF was performed under local anesthesia with conscious sedation, followed by decompression through endoscopic technics. After that, end-plate preparation and autogenous bone and expandable cage implantation were performed. Finally, percutaneous screws and rod instrumentation were used. The visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical efficacy. The operation time, intraoperative bleeding volume, intraoperative and postoperative complications were recorded. All patients underwent X-ray, CT plain scan, three-dimensional reconstruction and MRI examination to evaluate the stability of the implants and fusion rate before 3 days and 1, 3, 6, 12 and 18 months after operation. RESULTS: All patients were followed up, and the duration ranged from 12 to 18 months. The operation time of single-segment fusion was (192.3±22.7) min, and that of double-segment fusion was (272.5±24.7) min. The estimated intraoperative bleeding volume was less than 50 ml per segment, and no blood transfusion was performed in all patients. The VAS improved from preoperative 7.4±1.1 to postoperative 2.3±0.8 (t=-19.65, P<0.000 5). The ODI improved from preoperative (41.2±3.3)% to the final follow-up (12.3±2.5)%(t=-35.76, P<0.000 5). Postoperative complications occurred in 4 cases, and contralateral radicular symptoms occurred in 2 cases. After contralateral foraminoscopic decompression, the symptoms were completely alleviated. One case had neurological symptoms related to percutaneous screw placement, and the symptoms were alleviated after removal of the lateral screw rod internal fixation. The other cases had surgical incision infection and improved after debridement and suture. At the latest follow-up, no displacement or loosening of the fusion cage and screw rod system occurred in all patients, and 14 cases showed signs of fusion. CONCLUSIONS: PT-Endo-LIF is a minimal invasive, safe and efficient surgical procedure for treatment of degenerative lumbar disease. Nevertheless, the long-term results still need to be confirmed by a multi-center and lagre sample follow-up study.