Journal Club: Autophagy in spiral ganglion neuron as therapeutic target in cisplatin-ototoxicity

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Today's journal article

Wang F, Xu Y, Wang Y, Liu Q, Li Y, Zhang W, Nong H, Zhang J, Zhao H, Yang H, Guo L, Li J, Li H, Yang Q. FAM134B-mediated endoplasmic reticulum autophagy protects against cisplatin-induced spiral ganglion neuron damage. 

Why I picked this article

This study investigates a protein called FAM134B as a potential therapeutic target for preventing sensorineural hearing loss in patients receiving cisplatin treatment. 

Cisplatin is a chemotherapy drug used to treat a wide range of malignant tumours, including paediatric cancers. While it is effective, it comes with side effects; one of the most common side effects is sensorineural hearing loss. Given the impact of hearing loss on quality of life, it is important to reduce the chance of side effects like hearing loss for the long-term well-being of the patient. 

Cells have adaptive responses to toxic agents, including cisplatin, presumably as part of a survival mechanism. When proteins in the cell are damaged by toxic agents like cisplatin, cells try to break down the damaged protein in a process called "autophagy". During this process, small functional compartments or organelles in each cell play a very important part. In particular, organelles such as the "lysosome" and the "endoplasmic reticulum" are important in protein breakdown and renewal. 

This study builds on the previous research that if autophagy and problems in the endoplasmic reticulum are not regulated well, cells will die via programmed cell death (= apoptosis).  The protein FAM134B (other names = JK 1, RETREG1) may be involved in regulating such a balance, and this is investigated in the present study. 

Part of Figure 4a, Wang et al (2025)

Some of the research findings

Animal model:

  • Wild-type (WT) C57BL/6 mice (4-day-old, 1 month, 4 month, and 12-month-old)
  • Cultured spiral ganglion neurons were prepared from 4-day-old mouse cochleae, and cultured in DMEM/ F12 media supplemented with other factors. 
  • Cisplatin toxicity was modelled by using 30 μM cisplatin in the cisplatin group. 
  • Autophagy was manipulated by pre-treating (for 6 hours) with: 
    • autophagy activator, RAPA (100 nM), or 
    • autophagy inhibitor, 3-MA (5 mM)

Detection of FAM134B

  • Microscopy, using antibody: anti-FAM134B antibody (1: 1000, 83414S, CST)
  • Other antibodies used: anti-LC3B antibody (1:1000, AB48394, Abcam), anti-cleaved caspase-3 antibody (1:1000, 9664S, CST), anti-caspase 12 antibody (1:1000, 35965S, CST), anti-Bcl-2 antibody (1:1000, A19693, Abclonal), anti-P-IRE1α antibody (1:1000, AB124945, Abcam), and anti-β-actin antibody (1:1000, GB11001, Servicbio)
Finding
  • The target protein, FAM134B, was found in the cytoplasm (space inside the cell but not the nucleus) of the auditory neurons = spiral ganglion cells (microscopy). The amount of FAM134B protein seems to be high at P5, decreases later and increases again at 12-month-old age. 
  • When cisplatin toxicity was modelled in cultured spiral ganglion neurons, the neurons slowly died over 24 hours via programmed cell death. 
  • When cisplatin toxicity induced neuron cell death in culture, the amount of FAM134B protein also decreased. 
  • Autophagy activator reduced death of spiral ganglion neurons by cisplatin treatment, while the opposite was the case with the autophagy inhibitor. 
  • In terms of FAM134B level, the autophagy inhibitor mitigated the effect of cisplatin, while the autophagy stimulator extended the effect of cisplatin treatment. 
  • When the FAM134B protein level was artificially decreased by genetic manipulation, the effect of cisplatin was aggravated.
Overall, the function of FAM134B and autophagy is important in increasing the survival of spiral ganglion neurons in cellular response to cisplatin exposure, in culture. 

Haruna's takeaway

By far, the majority of research on the pathophysiology of cisplatin-induced sensorineural hearing loss focuses on the role of reactive oxygen species. To reduce reactive oxygen species, antioxidants like NAC (compared and used in this publication too) are studied extensively. This study adds a different angle by investigating a newly discovered protein that can regulate some cellular responses during ototoxic stress. Autophagy is implicated in other pathologies other than cisplatin-induced hearing loss. It is hard to investigate organelles like the endoplasmic reticulum because they are so small, but it is also interesting to imagine how dynamic cells must be. It will be interesting to see how this may translate in live animals and with ageing and other stressors that affect spiral ganglion neurons. 

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This is Haruna's 14/100 of the 100-day challenge to post a science blog article every day! I love inner ear biology & cochlear physiology.