Deletion of Transmembrane protein 184b leads to retina degeneration in mice

TL;DR

Deleting the Tmem184b protein in mice causes retinal degeneration, affecting vision and leading to cell death and inflammation.

Contribution

This study identifies Tmem184b as a key protein in retinal health and reveals its deletion causes retinal degeneration in mice.

Findings

Tmem184b deletion in mice leads to retinal degeneration with loss of photoreceptor and neuronal cells.

KO mice show reduced ERG amplitudes and down-regulated photo-transduction proteins.

RNA sequencing shows down-regulated genes related to visual perception and hypoxia response.

Abstract

Transmembrane protein 184b (Tmem184b) has been implicated in axon degeneration and neuromuscular junction dysfunction. Notably, Tmem184b exhibits high expression levels in the retina; however, its specific function within this tissue remains poorly understood. To elucidate the role of Tmem184b in the mammalian visual system, we developed a Tmem184b knockout (KO) model for further investigation. Loss of Tmem184b led to significant decreases in both a and b wave amplitudes of scotopic electroretinogram (ERG) and reduced b wave amplitudes of photopic ERG, respectively, reflecting damage to both the photoreceptors and secondary neuronal cells of the retina. Histologic analyses showed a progressive retinal thinning accompanied by the significantly loss of retinal cells including cone, rod, bipolar, horizontal and retinal ganglion cells. The expression levels of photo‐transduction‐related proteins were down‐regulated in KO retina. TUNEL (terminal deoxynucleotidyl transferase‐mediated biotinylated Uridine‐5'‐triphosphate [UTP] nick end labelling) and glial fibrillary acidic protein (GFAP)‐labelling results suggested the increased cell death and inflammation in the KO mice. RNA‐sequencing analysis and GO enrichment analysis revealed that Tmem184b deletion resulted in down‐regulated genes involved in various biological processes such as visual perception, response to hypoxia, regulation of transmembrane transporter activity. Taken together, our study revealed essential roles of Tmem184b in the mammalian retina and confirmed the underlying mechanisms including cell death, inflammation and hypoxia pathway in the absence of Tmem184b, providing a potential target for therapeutic and diagnostic development.

Our study characterized the retinal phenotypes of Tmem184b KO mice and confirmed the underlying mechanisms including cell death, inflammation and response to hypoxia pathway for retinal degeneration (RD) in the absence of TMEM184B, providing a rationale for therapeutic and diagnostic applications of RD.

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