Abstract
In the mammalian organ of Corti (OC), the stereocilia on the apical surface of hair cells (HCs) are uniformly organized in a neural to abneural axis (or medial-laterally). This organization is regulated by planar cell polarity (PCP) signaling. Mutations of PCP genes, such as Vangl2, Dvl1/2, Celsr1, and Fzd3/6, affect the formation of HC orientation to varying degrees. Prickle1 is a PCP signaling gene that belongs to the prickle / espinas / testin family. Prickle1 protein is shown to be asymmetrically localized in the HCs of the OC, and this asymmetric localization is associated with loss of PCP in Smurf mutants, implying that Prickle1 is involved in HC PCP development in the OC. A follow-up study found no PCP polarity defects after loss of Prickle1 (Prickle1-/-) in the cochlea. We show here strong Prickle1 mRNA expression in the spiral ganglion by in situ hybridization and β-Gal staining, and weak expression in the OC by β-Gal staining. Consistent with this limited expression in the OC, cochlear HC PCP is unaffected in either Prickle1C251X/C251X mice or Prickle1f/f; Pax2-cre conditional null mice. Meanwhile, type II afferents of apical spiral ganglion neurons (SGN) innervating outer hair cells (OHC) have unusual neurite growth. In addition, afferents from the apex show unusual collaterals in the cochlear nuclei that overlap with basal turn afferents. Our findings argue against the role of Prickle1 in regulating hair cell polarity in the cochlea. Instead, Prickle1 regulates the polarity-related growth of distal and central processes of apical SGNs.
Highlights
The organ of Corti (OC), the mammalian sensory organ for hearing, is located within the cochlea, and is the most sophisticated cellular assembly of the mammalian body [1]
This contrasted to Vangl2, whose signal was strong in the OC at E15.5 (Fig 1B)
The function of Prickle1 has been closely linked with Wnt/Planar cell polarity (PCP) signaling in the development of several systems, such as limb [34], palate [35] and facial motor neurons [36]
Summary
The organ of Corti (OC), the mammalian sensory organ for hearing, is located within the cochlea, and is the most sophisticated cellular assembly of the mammalian body [1]. Its core members include Vang-like 1/2 (Vangl1/2), Frizzled class receptor 3/6 (Fzd3/6), Dishevelled segment polarity protein 1/2/3 (Dvl1/2/3), and Prickle planar cell polarity protein 1/2/3/4 (Prickle1/2/3/4), among others [4, 5]. Some of these core PCP proteins are localized asymmetrically at the cell membrane during PCP development: Vangl1/2 are expressed in HC-SC (supporting cell) boundary medial to HCs, mostly in the supporting cells [6,7,8]; Fzd3/6 are expressed in the medial side of HCs [9]; Dvl1/2/3 are expressed in the lateral side of HCs [10, 11]. Dvl3-/-; Vangl2Lp/+ mice have severely misoriented cochlear HCs while Dvl3-/- only have mild defects and no detectable defects in Vangl2Lp/+ cochlea [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
