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Olfactory bulb hypoplasia in Prokr2 mice stems from defective neuronal progenitor migration and differentiation.

Prosser HM, Bradley A, Caldwell MA - Eur. J. Neurosci. (2007)

Bottom Line: In addition, there are increased numbers of doublecortin-positive neuroblasts in the RMS and increased PSA-NCAM (polysialylated form of the neural cell adhesion molecule) -positive neuronal progenitors around the olfactory ventricle, indicating their detachment from homotypic chains is compromised.Finally, in support of this, Prokr2-deficient cells expanded in vitro as neurospheres are incapable of migrating towards a source of recombinant human prokineticin 2 (PROK2).Together, these findings suggest an important role for Prokr2 in OB neurogenesis.

View Article: PubMed Central - PubMed

Affiliation: The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK.

ABSTRACT
New neurons are added on a daily basis to the olfactory bulb (OB) of a mammal, and this phenomenon exists throughout its lifetime. These new cells are born in the subventricular zone and migrate to the OB via the rostral migratory stream (RMS). To examine the role of the prokineticin receptor 2 (Prokr2) in neurogenesis, we created a Prokr2 mouse, and report a decrease in the volume of its OB and also a decrease in the number of bromodeoxyuridine (BrdU)-positive cells. There is disrupted architecture of the OB, with the glomerular layer containing terminal dUTP nick-end labeling (TUNEL) -positive nuclei and also a decrease in tyrosine hydroxylase-positive neurons in this layer. In addition, there are increased numbers of doublecortin-positive neuroblasts in the RMS and increased PSA-NCAM (polysialylated form of the neural cell adhesion molecule) -positive neuronal progenitors around the olfactory ventricle, indicating their detachment from homotypic chains is compromised. Finally, in support of this, Prokr2-deficient cells expanded in vitro as neurospheres are incapable of migrating towards a source of recombinant human prokineticin 2 (PROK2). Together, these findings suggest an important role for Prokr2 in OB neurogenesis.

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TUNEL staining and cell proliferation in the OB. (A) +/+ OB showing lack of TUNEL staining compared with (B) TUNEL-positive staining in the m/m mice shown in higher-power magnification in (C) Note, staining is highest in the GL where architecture is distorted (see also Fig. 1). (D) There is a decrease in bromodeoxyuridine (BrdU) staining in the OB of m/m mice compared with +/+ or +/m 21 days after a single injection of BrdU (***P < 0.001 versus +/+, +/m; n = 6). (E) BrdU staining of OB in +/+ mice (magnification 5 ×). The boxed region in (E) is shown in the corner of (E). (F) BrdU staining in OB of m/m mice (magnification 5 ×), the boxed region in (F) is shown in the corner of (F). Note, the difference in size of the OB at 5 × magnification. Scale bars: 100 µm (A and B); 20 µm (C); 500 µm (E and F).
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fig02: TUNEL staining and cell proliferation in the OB. (A) +/+ OB showing lack of TUNEL staining compared with (B) TUNEL-positive staining in the m/m mice shown in higher-power magnification in (C) Note, staining is highest in the GL where architecture is distorted (see also Fig. 1). (D) There is a decrease in bromodeoxyuridine (BrdU) staining in the OB of m/m mice compared with +/+ or +/m 21 days after a single injection of BrdU (***P < 0.001 versus +/+, +/m; n = 6). (E) BrdU staining of OB in +/+ mice (magnification 5 ×). The boxed region in (E) is shown in the corner of (E). (F) BrdU staining in OB of m/m mice (magnification 5 ×), the boxed region in (F) is shown in the corner of (F). Note, the difference in size of the OB at 5 × magnification. Scale bars: 100 µm (A and B); 20 µm (C); 500 µm (E and F).

Mentions: The generation of the prokr2Brdm1 (abbreviated here to m) allele has been described elsewhere (Prosser et al., 2007). Anatomical analysis of the brain demonstrated that the sizes of the right and left OB were symmetrically reduced in m/m mice (n = 7) when compared with their +/+ littermate controls (n = 6; Fig. 1A–D) and +/m controls (n = 7; data not shown). In addition, the normal morphology of the OB was distorted, in that there was a distinct absence of the glomerular layer (GL), mitral cell layer and internal plexiform layer in m/m mice (Fig. 1E and F). Volumetric analysis of the m/m OB demonstrated that they are four times smaller than those of either +/+ or +/m littermates (Fig. 1D). In addition, the width of the OB was narrower in m/m mice than either their +/+ or +/m littermates (+/+ 870 + 33; +/m 880 + 40; m/m 395 + 20 µm). In order to determine if ongoing cell death contributes to the OB defect of the m/m mice, TUNEL staining was performed that revealed this was indeed the case (Fig. 2A–C). Interestingly, TUNEL-positive nuclei were most pronounced in the area that should constitute the missing GL (Fig. 2C). There was no difference in TUNEL-positive staining between m/m and control mice elsewhere in the brain (data not shown).


Olfactory bulb hypoplasia in Prokr2 mice stems from defective neuronal progenitor migration and differentiation.

Prosser HM, Bradley A, Caldwell MA - Eur. J. Neurosci. (2007)

TUNEL staining and cell proliferation in the OB. (A) +/+ OB showing lack of TUNEL staining compared with (B) TUNEL-positive staining in the m/m mice shown in higher-power magnification in (C) Note, staining is highest in the GL where architecture is distorted (see also Fig. 1). (D) There is a decrease in bromodeoxyuridine (BrdU) staining in the OB of m/m mice compared with +/+ or +/m 21 days after a single injection of BrdU (***P < 0.001 versus +/+, +/m; n = 6). (E) BrdU staining of OB in +/+ mice (magnification 5 ×). The boxed region in (E) is shown in the corner of (E). (F) BrdU staining in OB of m/m mice (magnification 5 ×), the boxed region in (F) is shown in the corner of (F). Note, the difference in size of the OB at 5 × magnification. Scale bars: 100 µm (A and B); 20 µm (C); 500 µm (E and F).
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fig02: TUNEL staining and cell proliferation in the OB. (A) +/+ OB showing lack of TUNEL staining compared with (B) TUNEL-positive staining in the m/m mice shown in higher-power magnification in (C) Note, staining is highest in the GL where architecture is distorted (see also Fig. 1). (D) There is a decrease in bromodeoxyuridine (BrdU) staining in the OB of m/m mice compared with +/+ or +/m 21 days after a single injection of BrdU (***P < 0.001 versus +/+, +/m; n = 6). (E) BrdU staining of OB in +/+ mice (magnification 5 ×). The boxed region in (E) is shown in the corner of (E). (F) BrdU staining in OB of m/m mice (magnification 5 ×), the boxed region in (F) is shown in the corner of (F). Note, the difference in size of the OB at 5 × magnification. Scale bars: 100 µm (A and B); 20 µm (C); 500 µm (E and F).
Mentions: The generation of the prokr2Brdm1 (abbreviated here to m) allele has been described elsewhere (Prosser et al., 2007). Anatomical analysis of the brain demonstrated that the sizes of the right and left OB were symmetrically reduced in m/m mice (n = 7) when compared with their +/+ littermate controls (n = 6; Fig. 1A–D) and +/m controls (n = 7; data not shown). In addition, the normal morphology of the OB was distorted, in that there was a distinct absence of the glomerular layer (GL), mitral cell layer and internal plexiform layer in m/m mice (Fig. 1E and F). Volumetric analysis of the m/m OB demonstrated that they are four times smaller than those of either +/+ or +/m littermates (Fig. 1D). In addition, the width of the OB was narrower in m/m mice than either their +/+ or +/m littermates (+/+ 870 + 33; +/m 880 + 40; m/m 395 + 20 µm). In order to determine if ongoing cell death contributes to the OB defect of the m/m mice, TUNEL staining was performed that revealed this was indeed the case (Fig. 2A–C). Interestingly, TUNEL-positive nuclei were most pronounced in the area that should constitute the missing GL (Fig. 2C). There was no difference in TUNEL-positive staining between m/m and control mice elsewhere in the brain (data not shown).

Bottom Line: In addition, there are increased numbers of doublecortin-positive neuroblasts in the RMS and increased PSA-NCAM (polysialylated form of the neural cell adhesion molecule) -positive neuronal progenitors around the olfactory ventricle, indicating their detachment from homotypic chains is compromised.Finally, in support of this, Prokr2-deficient cells expanded in vitro as neurospheres are incapable of migrating towards a source of recombinant human prokineticin 2 (PROK2).Together, these findings suggest an important role for Prokr2 in OB neurogenesis.

View Article: PubMed Central - PubMed

Affiliation: The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK.

ABSTRACT
New neurons are added on a daily basis to the olfactory bulb (OB) of a mammal, and this phenomenon exists throughout its lifetime. These new cells are born in the subventricular zone and migrate to the OB via the rostral migratory stream (RMS). To examine the role of the prokineticin receptor 2 (Prokr2) in neurogenesis, we created a Prokr2 mouse, and report a decrease in the volume of its OB and also a decrease in the number of bromodeoxyuridine (BrdU)-positive cells. There is disrupted architecture of the OB, with the glomerular layer containing terminal dUTP nick-end labeling (TUNEL) -positive nuclei and also a decrease in tyrosine hydroxylase-positive neurons in this layer. In addition, there are increased numbers of doublecortin-positive neuroblasts in the RMS and increased PSA-NCAM (polysialylated form of the neural cell adhesion molecule) -positive neuronal progenitors around the olfactory ventricle, indicating their detachment from homotypic chains is compromised. Finally, in support of this, Prokr2-deficient cells expanded in vitro as neurospheres are incapable of migrating towards a source of recombinant human prokineticin 2 (PROK2). Together, these findings suggest an important role for Prokr2 in OB neurogenesis.

Show MeSH
Related in: MedlinePlus