Figure 1
From: The precision of axon targeting of mouse olfactory sensory neurons requires the BACE1 protease
BACE1 expression in mouse olfactory epithelium and olfactory bulb is activity dependent.
(a – c) BACE1 immunoreactivity (IR) is enriched in the axon bundles (arrows) of olfactory sensory neurons (OSNs), where it is colocalized with NCAM, an axon-specific marker protein. The insets indicate that BACE1 is partially colocalized with NCAM in the axon bundles. (d) BACE1 IR is present in the olfactory bulb, with the highest level in the glomerular layer (GL), a modest level in the external plexiform layer (EPL) and absent in the mitral cell layer (MCL). (e – f) BACE1 IR is reduced in BACE1 heterozygous mice (BACE1 +/−) and absent in BACE1 homozygous knockout mice (BACE1 −/−). (g) Quantification of BACE1 IR intensity in the olfactory bulb. (h – i) In situ hybridization reveals graded levels of BACE1 mRNA in the olfactory epithelium (h) and robust staining in the mitral cell layer of the olfactory bulb (i). Unilateral naris closure in control mice reveals a marked increase in the BACE1 mRNA levels on the closed side of the olfactory epithelium (j) but not in the mitral cells of the olfactory bulb (k). Quantitation of the BACE1 protein levels in the glomeruli of the olfactory bulb (l) reveals significant increases (m) in the dorsal, medial and lateral regions of the olfactory bulb (p < 0.001). Black bars represent closed side and gradient bars represent the open side.
