Learning Objectives:

Introduction: Wolfram syndrome is an autosomal recessive disorder, known as DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, and Deafness) syndrome. Its causative gene, WFS1, encodes an 890 amino acid protein, called WOLFRAMIN, which maintains calcium homeostasis and unfolded protein responses in the endoplasmic reticulum (ER). Limited literatures describing temporal bone pathology display loss of hair cells in the basal turn and atrophy of stria vascularis in the apical turn. However, the expression of Wolframin in mice was distributed widely and uniformly in the sensory epithelium and was absent in the stria vascularis. Moreover, WFS1 knockout mice did not suffer deafness.

Learning objectives: In order to elucidate the discrepancy of the phenotype among species, and to explore the pathophysiology of deafness associated with WFS1 mutations, we examined expression of WOLFRAMIN in a non-human primate, common marmoset (Callithrix jacchus), cochlea.

Methods: We examined the expression pattern of WOLFRAMIN with double staining of WFS1 with other markers. The primary antibodies used are as follows: anti-WFS1 (rabbit IgG), anti-MYOSIN7a (mouse IgG), anti-CALDESMON (mouse IgG), and anti-CONNEXIN26 (CX26) (mouse IgG).

Results: In marmoset cochlea, WFS1 immunoreactivity was observed in basal cells of stria vascularis, type I fibrocytes, outer hair cells, outer sulcus cells, Claudius cells, Hensen cells, and spiral ganglion. Immunostaining for WFS1 was co-labled with type I fibrocytes markers, CX26 and CALDESMON. In stria vascularis, immunoreactivity for WFS1 was co-labeled with a basal cell marker, CX26.

Conclusions: The expression pattern of WFS1 in common marmoset cochlea was different from that of mouse. The pattern suggests basal cells may play essential roles in the maintenance of stria vascularis. Clarifying the function of basal cells of primates, including human, may elucidate pathogenesis of hearing loss in Wolfram syndrome patients.