CD82 Protects Against Glaucomatous Axonal Transport Deficits via mTORC1 Activation in Mice

Abstract Background: Glaucoma is a leading cause of irreversible blindness worldwide characterized by progressive optic nerve degeneration and retinal ganglion cell (RGC) loss. Axonal transport deficits have been demonstrated to be the earliest crucial pathophysiological changes underlying axonal degeneration in glaucoma. The critical feature of this pathological process and the significance of early intervention remain to be further explored. Here, we explore the role of a tetraspanin superfamily member CD82 in protection of glaucomatous neurodegeneration in an acute ocular hypertension mouse model. Methods:Expression level of CD82 in retina was examined before and after an acute ocular hypertension (AOHT) model in mouse. Overexpression of CD82 was achieved by intraocular injection of adeno-associated virus vector expressing CD82. Axonal transport deficits were evaluated by intravitreally injected Cholera toxin B (CTB) from eyes to superior colliculus and the distribution of endogenous synaptophysin. Subsequent optic nerve (ON) degeneration phenotypes were also examined including axon loss, myelin damage, and Aβ accumulation. In vitro neurite outgrowth assay was performed in SH-SY5Y cells with Cd82-plasmid transfection. Another optic nerve crush (ONC) model was taken to further validate the neuroprotective effects of CD82 by evaluation of axonal regeneration, RGC survival, and visual function of mice. Downstream pathway of CD82 was analyzed by qPCR examination and western blotting analysis as well as phenotype detection.Results:We found a transient downregulation of CD82 after acute IOP elevation, with parallel emergence of axonal transport deficits. Overexpression of CD82 with AAV2/9 vector in mouse retina improved optic nerve (ON) axonal transport and ameliorated subsequent axon degeneration. In vitro neurite outgrowth assay displayed longer neurite length of SH-SY5Y cells with transfection of Cd82-plasmid. Moreover, CD82 overexpression could stimulate ON regeneration and restore mouse vision after an optic nerve crush model. CD82 exerted protective effect through upregulation of TRAF2, which was an E3 ubiquitin ligase and activated mTORC1 through K63-linked ubiquitylation and intracellular repositioning of Raptor. Conclusions:These findings indicate that CD82 overexpression protects against glaucomatous axonal transport deficits through TRAF2-dependent activation of mTORC1 pathway, which offers deeper insights into tetraspanins superfamily and demonstrated potential neuroprotective strategy in glaucoma treatments.

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CD82 protects against glaucomatous axonal transport deficits via mTORC1 activation in mice

Cell Death and Disease ◽

10.1038/s41419-021-04445-6 ◽

2021 ◽

Vol 12 (12) ◽

Author(s):

Meng Ye ◽

Jingqiu Huang ◽

Qianxue Mou ◽

Jing Luo ◽

Yuanyuan Hu ◽

...

Keyword(s):

Optic Nerve ◽

Axonal Transport ◽

Cell Loss ◽

Nerve Degeneration ◽

Mouse Retina ◽

Retinal Ganglion ◽

Nerve Crush ◽

Neuroprotective Strategy ◽

Mtorc1 Activation

AbstractGlaucoma is a leading cause of irreversible blindness worldwide and is characterized by progressive optic nerve degeneration and retinal ganglion cell loss. Axonal transport deficits have been demonstrated to be the earliest crucial pathophysiological changes underlying axonal degeneration in glaucoma. Here, we explored the role of the tetraspanin superfamily member CD82 in an acute ocular hypertension model. We found a transient downregulation of CD82 after acute IOP elevation, with parallel emergence of axonal transport deficits. The overexpression of CD82 with an AAV2/9 vector in the mouse retina improved optic nerve axonal transport and ameliorated subsequent axon degeneration. Moreover, the CD82 overexpression stimulated optic nerve regeneration and restored vision in a mouse optic nerve crush model. CD82 exerted a protective effect through the upregulation of TRAF2, which is an E3 ubiquitin ligase, and activated mTORC1 through K63-linked ubiquitylation and intracellular repositioning of Raptor. Therefore, our study offers deeper insight into the tetraspanin superfamily and demonstrates a potential neuroprotective strategy in glaucoma treatment.

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Rapid initiation of neurite outgrowth onto laminin from explants of adult mouse retina induced by optic nerve crush

Experimental Neurology ◽

10.1016/0014-4886(90)90138-i ◽

1990 ◽

Vol 107 (3) ◽

pp. 214-221 ◽

Cited By ~ 18

Author(s):

Ronald L. Meyer ◽

Jill Miotke

Keyword(s):

Optic Nerve ◽

Neurite Outgrowth ◽

Adult Mouse ◽

Mouse Retina ◽

Optic Nerve Crush ◽

Nerve Crush

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Citrus Naringenin Increases Neuron Survival in Optic Nerve Crush Injury Model by Inhibiting JNK-JUN Pathway

International Journal of Molecular Sciences ◽

10.3390/ijms23010385 ◽

2021 ◽

Vol 23 (1) ◽

pp. 385

Author(s):

Jie Chen ◽

Hui Li ◽

Changming Yang ◽

Yinjia He ◽

Tatsuo Arai ◽

...

Keyword(s):

Optic Nerve ◽

Nerve Injury ◽

Ganglion Cells ◽

Crush Injury ◽

Optic Nerve Crush ◽

Nerve Crush ◽

Injury Model ◽

Nerve Crush Injury

Traumatic nerve injury activates cell stress pathways, resulting in neuronal death and loss of vital neural functions. To date, there are no available neuroprotectants for the treatment of traumatic neural injuries. Here, we studied three important flavanones of citrus components, in vitro and in vivo, to reveal their roles in inhibiting the JNK (c-Jun N-terminal kinase)-JUN pathway and their neuroprotective effects in the optic nerve crush injury model, a kind of traumatic nerve injury in the central nervous system. Results showed that both neural injury in vivo and cell stress in vitro activated the JNK-JUN pathway and increased JUN phosphorylation. We also demonstrated that naringenin treatment completely inhibited stress-induced JUN phosphorylation in cultured cells, whereas nobiletin and hesperidin only partially inhibited JUN phosphorylation. Neuroprotection studies in optic nerve crush injury mouse models revealed that naringenin treatment increased the survival of retinal ganglion cells after traumatic optic nerve injury, while the other two components had no neuroprotective effect. The neuroprotection effect of naringenin was due to the inhibition of JUN phosphorylation in crush-injured retinal ganglion cells. Therefore, the citrus component naringenin provides neuroprotection through the inhibition of the JNK-JUN pathway by inhibiting JUN phosphorylation, indicating the potential application of citrus chemical components in the clinical therapy of traumatic optic nerve injuries.

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miRNA Changes in Retinal Ganglion Cells after Optic Nerve Crush and Glaucomatous Damage

Cells ◽

10.3390/cells10071564 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1564

Author(s):

Ben Mead ◽

Alicia Kerr ◽

Naoki Nakaya ◽

Stanislav I. Tomarev

Keyword(s):

Optic Nerve ◽

Ocular Hypertension ◽

Retinal Ganglion Cells ◽

Ganglion Cells ◽

Optic Nerve Crush ◽

Retinal Ganglion ◽

Nerve Crush ◽

Rat Retina ◽

Retinal Injury ◽

Generation Sequencing

The purpose of this study was to characterize the miRNA profile of purified retinal ganglion cells (RGC) from healthy and diseased rat retina. Diseased retina includes those after a traumatic optic nerve crush (ONC), and after ocular hypertension/glaucoma. Rats were separated into four groups: healthy/intact, 7 days after laser-induced ocular hypertension, 2 days after traumatic ONC, and 7 days after ONC. RGC were purified from rat retina using microbeads conjugated to CD90.1/Thy1. RNA were sequenced using Next Generation Sequencing. Over 100 miRNA were identified that were significantly different in diseased retina compared to healthy retina. Considerable differences were seen in the miRNA expression of RGC 7 days after ONC, whereas after 2 days, few changes were seen. The miRNA profiles of RGC 7 days after ONC and 7 days after ocular hypertension were similar, but discrete miRNA differences were still seen. Candidate mRNA showing different levels of expression after retinal injury were manipulated in RGC cultures using mimics/AntagomiRs. Of the five candidate miRNA identified and subsequently tested for therapeutic efficacy, miR-194 inhibitor and miR-664-2 inhibitor elicited significant RGC neuroprotection, whereas miR-181a mimic and miR-181d-5p mimic elicited significant RGC neuritogenesis.

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The levels and significance of inflammasomes in the mouse retina following optic nerve crush

International Immunopharmacology ◽

10.1016/j.intimp.2019.03.029 ◽

2019 ◽

Vol 71 ◽

pp. 313-320 ◽

Cited By ~ 4

Author(s):

Zheng Qijun ◽

Zou Huan ◽

Gao Ling ◽

Chen Kaijian ◽

Liu Wei ◽

...

Keyword(s):

Optic Nerve ◽

Mouse Retina ◽

Optic Nerve Crush ◽

Nerve Crush

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Differential Effects of Immunophilin-Ligands (FK506 and V-10,367) on Survival and Regeneration of Rat Retinal Ganglion Cells In Vitro and after Optic Nerve Crush In Vivo

Journal of Neurotrauma ◽

10.1089/089771503321532888 ◽

2003 ◽

Vol 20 (3) ◽

pp. 297-307 ◽

Cited By ~ 20

Author(s):

Philip Rosenstiel ◽

Peter Schramm ◽

Stefan Isenmann ◽

Stefan Brecht ◽

Christian Eickmeier ◽

...

Keyword(s):

Optic Nerve ◽

Retinal Ganglion Cells ◽

Ganglion Cells ◽

Optic Nerve Crush ◽

Retinal Ganglion ◽

Nerve Crush ◽

Differential Effects

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Ligand-Induced GPR110 Activation Facilitates Axon Growth after Injury

International Journal of Molecular Sciences ◽

10.3390/ijms22073386 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3386

Author(s):

Heungsun Kwon ◽

Karl Kevala ◽

Hu Xin ◽

Samarjit Patnaik ◽

Juan Marugan ◽

...

Keyword(s):

Optic Nerve ◽

Neurite Outgrowth ◽

Nerve Injury ◽

Cortical Neurons ◽

Axon Growth ◽

Neurite Growth ◽

Nerve Crush ◽

Developing Neurons

Recovery from axonal injury is extremely difficult, especially for adult neurons. Here, we demonstrate that the activation of G-protein coupled receptor 110 (GPR110, ADGRF1) is a mechanism to stimulate axon growth after injury. N-docosahexaenoylethanolamine (synaptamide), an endogenous ligand of GPR110 that promotes neurite outgrowth and synaptogenesis in developing neurons, and a synthetic GPR110 ligand stimulated neurite growth in axotomized cortical neurons and in retinal explant cultures. Intravitreal injection of GPR110 ligands following optic nerve crush injury promoted axon extension in adult wild-type, but not in gpr110 knockout, mice. In vitro axotomy or in vivo optic nerve injury rapidly induced the neuronal expression of gpr110. Activating the developmental mechanism of neurite outgrowth by specifically targeting GPR110 that is upregulated upon injury may provide a novel strategy for stimulating axon growth after nerve injury in adults.

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