Clarin-1 expression in adult mouse and human retina highlights a role of Müller glia in Usher syndrome

Lei Xu, Susan N. Bolch, Clayton P. Santiago, Frank M. Dyka, Omar Akil, Ekaterina S. Lobanova, Yuchen Wang, Kirill A. Martemyanov, William W. Hauswirth, W. Clay Smith, James T. Handa, Seth Blackshaw, John D. Ash, Astra Dinculescu

Research output: Contribution to journalArticle

Abstract

Usher syndrome type 3 (USH3) is an autosomal recessively inherited disorder caused by mutations in the gene clarin-1 (CLRN1), leading to combined progressive hearing loss and retinal degeneration. The cellular distribution of CLRN1 in the retina remains uncertain, either because its expression levels are low or because its epitopes are masked. Indeed, in the adult mouse retina, Clrn1 mRNA is developmentally downregulated, detectable only by RT-PCR. In this study we used the highly sensitive RNAscope in situ hybridization assay and single-cell RNA-sequencing techniques to investigate the distribution of Clrn1 and CLRN1 in mouse and human retina, respectively. We found that Clrn1 transcripts in mouse tissue are localized to the inner retina during postnatal development and in adult stages. The pattern of Clrn1 mRNA cellular expression is similar in both mouse and human adult retina, with CLRN1 transcripts being localized in Müller glia, and not photoreceptors. We generated a novel knock-in mouse with a hemagglutinin (HA) epitope-tagged CLRN1 and showed that CLRN1 is expressed continuously at the protein level in the retina. Following enzymatic deglycosylation and immunoblotting analysis, we detected a single CLRN1-specific protein band in homogenates of mouse and human retina, consistent in size with the main CLRN1 isoform. Taken together, our results implicate Müller glia in USH3 pathology, placing this cell type to the center of future mechanistic and therapeutic studies to prevent vision loss in this disease.

Original languageEnglish (US)
Pages (from-to)195-204
Number of pages10
JournalJournal of Pathology
Volume250
Issue number2
DOIs
StatePublished - Feb 1 2020

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Keywords

  • Müller glia
  • Usher syndrome pathology
  • clarin-1 expression
  • human retina
  • retinal degeneration
  • transcriptomic analysis

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Xu, L., Bolch, S. N., Santiago, C. P., Dyka, F. M., Akil, O., Lobanova, E. S., Wang, Y., Martemyanov, K. A., Hauswirth, W. W., Smith, W. C., Handa, J. T., Blackshaw, S., Ash, J. D., & Dinculescu, A. (2020). Clarin-1 expression in adult mouse and human retina highlights a role of Müller glia in Usher syndrome. Journal of Pathology, 250(2), 195-204. https://doi.org/10.1002/path.5360