Conditional Deletion of Activating Rearranged During Transfection Receptor Tyrosine Kinase Leads to Impairment of Photoreceptor Ribbon Synapses and Disrupted Visual Function in Mice

Wei-Hao Peng; Meng-Lin Liao; Wan-Chun Huang; Pei-Kang Liu; Sarah R Levi; Yun-Ju Tseng; Chia-Ying Lee; Lung-Kun Yeh; Kuan-Jen Chen; Chung-Liang Chien; Nan-Kai Wang

doi:10.3389/fnins.2021.728905

Conditional Deletion of Activating Rearranged During Transfection Receptor Tyrosine Kinase Leads to Impairment of Photoreceptor Ribbon Synapses and Disrupted Visual Function in Mice

Front Neurosci. 2021 Nov 5:15:728905. doi: 10.3389/fnins.2021.728905. eCollection 2021.

Authors

Wei-Hao Peng¹, Meng-Lin Liao², Wan-Chun Huang², Pei-Kang Liu^{3

4

5

6}, Sarah R Levi⁶, Yun-Ju Tseng⁶, Chia-Ying Lee⁷, Lung-Kun Yeh^{7

8}, Kuan-Jen Chen^{7

8}, Chung-Liang Chien², Nan-Kai Wang⁶

Affiliations

¹ School of Medicine for International Students, College of Medicine, I-Shou University, Kaohsiung, Taiwan.
² Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
³ Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁴ School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁵ Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan.
⁶ Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, New York, NY, United States.
⁷ Department of Ophthalmology, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
⁸ College of Medicine, Chang Gung University, Taoyuan, Taiwan.

Abstract

Purpose: The rearranged during transfection (RET) receptor tyrosine kinase plays a key role in transducing signals related to cell growth and differentiation. Ret mutant mice show abnormal retinal activity and abnormal levels and morphology of bipolar cells, yet die on the 21^st day after birth as a result of renal underdevelopment. To extend the observation period, we generated the Ret conditional knockout Chx10-Cre;C-Ret ^lx/lx mouse model and analyzed the retinal function and morphological changes in mature and aging Chx10-Cre;C-Ret ^lx/lx mice. Methods: Retina-specific depletion of Ret was achieved using mice with floxed alleles of the Ret gene with CHX10-driven Cre recombinase; floxed mice without Cre expression were used as controls. Retinal function was examined using electroretinography (ERG), and 2-, 4-, 12-, and 24-month-old mice were analyzed by hematoxylin staining and immunohistochemistry to evaluate retinal morphological alterations. The ultrastructure of photoreceptor synapses was evaluated using electron microscopy. Results: The results of the ERG testing showed that b-wave amplitudes were reduced in Chx10-Cre;C-Ret ^lx/lx mice, whereas a-waves were not affected. A histopathological analysis revealed a thinner and disorganized outer plexiform layer at the ages of 12 and 24 months in Chx10-Cre;C-Ret ^lx/lx mice. Moreover, the data provided by immunohistochemistry showed defects in the synapses of photoreceptor cells. This result was confirmed at the ultrastructural level, thus supporting the participation of Ret in the morphological changes of the synaptic ribbon. Conclusion: Our results provide evidence of the role of Ret in maintaining the function of the retina, which was essential for preserving the structure of the synaptic ribbon and supporting the integrity of the outer plexiform layer.

Keywords: Cre-loxP knockout mice; GDNF family of ligands (GFL); mouse retina; rearranged during transfection (RET); ribbon synapses.

Abstract

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