TSHZ1-dependent gene regulation is essential for olfactory bulb development and olfaction
Daniela Ragancokova, Elena Rocca, Anne M.M. Oonk, Herbert Schulz, Elvira Rohde, Jan Bednarsch, Ilse Feenstra, Ronald J.E. Pennings, Hagen Wende, Alistair N. Garratt
Daniela Ragancokova, Elena Rocca, Anne M.M. Oonk, Herbert Schulz, Elvira Rohde, Jan Bednarsch, Ilse Feenstra, Ronald J.E. Pennings, Hagen Wende, Alistair N. Garratt
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Research Article Development Genetics Neuroscience

TSHZ1-dependent gene regulation is essential for olfactory bulb development and olfaction

Abstract

The olfactory bulb (OB) receives odor information from the olfactory epithelium and relays this to the olfactory cortex. Using a mouse model, we found that development and maturation of OB interneurons depends on the zinc finger homeodomain factor teashirt zinc finger family member 1 (TSHZ1). In mice lacking TSHZ1, neuroblasts exhibited a normal tangential migration to the OB; however, upon arrival to the OB, the neuroblasts were distributed aberrantly within the radial dimension, and many immature neuroblasts failed to exit the rostral migratory stream. Conditional deletion of Tshz1 in mice resulted in OB hypoplasia and severe olfactory deficits. We therefore investigated olfaction in human subjects from families with congenital aural atresia that were heterozygous for TSHZ1 loss-of-function mutations. These individuals displayed hyposmia, which is characterized by impaired odor discrimination and reduced olfactory sensitivity. Microarray analysis, in situ hybridization, and ChIP revealed that TSHZ1 bound to and regulated expression of the gene encoding prokineticin receptor 2 (PROKR2), a G protein–coupled receptor essential for OB development. Mutations in PROKR2 lead to Kallmann syndrome, characterized by anosmia and hypogonadotrophic hypogonadism. Our data indicate that TSHZ1 is a key regulator of mammalian OB development and function and controls the expression of molecules involved in human Kallmann syndrome.

Authors

Daniela Ragancokova, Elena Rocca, Anne M.M. Oonk, Herbert Schulz, Elvira Rohde, Jan Bednarsch, Ilse Feenstra, Ronald J.E. Pennings, Hagen Wende, Alistair N. Garratt

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Figure 9

Tshz1 regulates expression of Prokr2 in the OB.

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Tshz1 regulates expression of Prokr2 in the OB. (A–D) Coronal sections ...
(A–D) Coronal sections of OBs were examined by in situ hybridization using the indicated probes. (A) Tshz1 was expressed in both the RMSOB (arrow) and the outer granule cell layer (arrowhead) in control mice. (B) Prokr2 expression in the RMSOB (arrow) was strongly reduced in Tshz1 mutants at E18.5. (C) In postnatal OB, Prokr2 was expressed in the RMSOB (arrows) of controls and coTshz1 mutants, while radially migrating Prokr2-expressing neuroblasts were absent in the latter (insets; dotted lines denote lateral border of RMSOB). (D) Expression of the ligand PK2 in a subpopulation of granule cells was severely reduced in coTshz1 mutants. (E) Prokr2 gene. The positions of primers flanking the putative TSHZ1 binding site in intron 1 (red) and a site in the promoter region (orange) that served as a negative control for PCR after ChIP are denoted by arrows. Exons 1–3 (E1–E3), including the coding sequences (cds; white) or 5¢- and 3¢-untranslated regions (UTR; gray), are also shown. (F) Anti-TSHZ1 or preimmune serum (pre-IS) were used in ChIP of OB tissue, and interactions were tested using conventional PCR with primer pairs in the promoter region or intron 1. (G) Quantitative PCR after anti-TSHZ1 ChIP, normalized to levels with preimmune serum, revealed significant enrichment for binding of TSHZ1 to intron 1 of Prokr2. *P = 0.018. Scale bars: 500 μm (C and D), 200 μm (A and B), 50 μm (C and D, insets).