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A novel member of the netrin family, beta-netrin, shares homology with the beta chain of laminin: identification, expression, and functional characterization.

Koch M, Murrell JR, Hunter DD, Olson PF, Jin W, Keene DR, Brunken WJ, Burgeson RE - J. Cell Biol. (2000)

Bottom Line: In addition, beta-netrin is expressed in a limited set of fiber tracts within the brain, including the lateral olfactory tract and the vomeronasal nerve.Functional studies were performed and show that beta-netrin promotes neurite elongation from olfactory bulb explants.Together, these data suggest that beta-netrin is important in neural, kidney, and vascular development.

View Article: PubMed Central - PubMed

Affiliation: Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.

ABSTRACT
The netrins are a family of laminin-related molecules. Here, we characterize a new member of the family, beta-netrin. beta-Netrin is homologous to the NH(2) terminus of laminin chain short arms; it contains a laminin-like domain VI and 3.5 laminin EGF repeats and a netrin C domain. Unlike other netrins, this new netrin is more related to the laminin beta chains, thus, its name beta-netrin. An initial analysis of the tissue distribution revealed that kidney, heart, ovary, retina, and the olfactory bulb were tissues of high expression. We have expressed the molecule in a eukaryotic cell expression system and made antibodies to the expressed product. Both in situ hybridization and immunohistochemistry were used to describe the cellular source of beta-netrin and where beta-netrin is deposited. beta-Netrin is a basement membrane component; it is present in the basement membranes of the vasculature, kidney, and ovaries. In addition, beta-netrin is expressed in a limited set of fiber tracts within the brain, including the lateral olfactory tract and the vomeronasal nerve. Functional studies were performed and show that beta-netrin promotes neurite elongation from olfactory bulb explants. Together, these data suggest that beta-netrin is important in neural, kidney, and vascular development.

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β-Netrin produces neurite outgrowth from olfactory bulb explants. (A–C) Representative cultures treated as indicated. Treatment with rβNΔC or full-length rβN proteins increases the number of neurites produced by the explants. (D) Quantification of data obtained on neurite outgrowth; the total length of all neurites produced by explants is given here (Sum Length). Protein additions are noted below the bars; the line indicates that cultures were treated identically; the concentrations of protein additions are noted below the line. β-Netrin conventions are as above; 14 nM + AB indicates the simultaneous addition of 14 nM βN and pooled polyclonal antisera to βN. γ2SA denotes the short arm of the laminin γ2 chain; similar conventions are used for γ3 and β2 chains. * Statistically significant difference versus control; # statistically significant difference versus 14 nM βN or 9 nM γ3SA, respectively; P < 0.05.
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Figure 10: β-Netrin produces neurite outgrowth from olfactory bulb explants. (A–C) Representative cultures treated as indicated. Treatment with rβNΔC or full-length rβN proteins increases the number of neurites produced by the explants. (D) Quantification of data obtained on neurite outgrowth; the total length of all neurites produced by explants is given here (Sum Length). Protein additions are noted below the bars; the line indicates that cultures were treated identically; the concentrations of protein additions are noted below the line. β-Netrin conventions are as above; 14 nM + AB indicates the simultaneous addition of 14 nM βN and pooled polyclonal antisera to βN. γ2SA denotes the short arm of the laminin γ2 chain; similar conventions are used for γ3 and β2 chains. * Statistically significant difference versus control; # statistically significant difference versus 14 nM βN or 9 nM γ3SA, respectively; P < 0.05.

Mentions: Because of the similarity in structure of β-netrin to netrins 1–3, and because β-netrin expression was detected in the output pathways of the olfactory bulb and the retina, we tested the ability of β-netrin to promote neurite outgrowth. Explants of E15 rat olfactory bulb were dissected, embedded in collagen gels, and incubated with soluble recombinant full-length and truncated β-netrin (rβ-N and rβ-NΔC; Fig. 10). In control cultures, neurites extend around the circumference of the explant (Fig. 10 A). Treatment with rβ-netrin increases both the neurite length and the number of neurites extending from cultures (Fig. 10B and Fig. C). We measured several parameters of this increase in neurite outgrowth including the following: total number of neurites; average neurite length; total length of neurites (sum neurite length); and total neurite area (Table ). By all measures, the addition of rβ-N produced an increase in neurite outgrowth; these data are shown graphically in Fig. 10. With the addition of rβ-N, there was a dose-dependent increase in both the sum length of all neurites and the number of neurites (normalized to explant circumference) of up to 400% of control measurements (Fig. 10D and Fig. E, Fig. rβ-N); values in the presence of all but the lowest concentration of rβ-N were statistically different from control values (P < 0.05). The addition of an affinity-purified preparation of pooled anti–β-netrin antisera antagonized this effect, reducing neurite length and number to control levels.


A novel member of the netrin family, beta-netrin, shares homology with the beta chain of laminin: identification, expression, and functional characterization.

Koch M, Murrell JR, Hunter DD, Olson PF, Jin W, Keene DR, Brunken WJ, Burgeson RE - J. Cell Biol. (2000)

β-Netrin produces neurite outgrowth from olfactory bulb explants. (A–C) Representative cultures treated as indicated. Treatment with rβNΔC or full-length rβN proteins increases the number of neurites produced by the explants. (D) Quantification of data obtained on neurite outgrowth; the total length of all neurites produced by explants is given here (Sum Length). Protein additions are noted below the bars; the line indicates that cultures were treated identically; the concentrations of protein additions are noted below the line. β-Netrin conventions are as above; 14 nM + AB indicates the simultaneous addition of 14 nM βN and pooled polyclonal antisera to βN. γ2SA denotes the short arm of the laminin γ2 chain; similar conventions are used for γ3 and β2 chains. * Statistically significant difference versus control; # statistically significant difference versus 14 nM βN or 9 nM γ3SA, respectively; P < 0.05.
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Related In: Results  -  Collection

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Figure 10: β-Netrin produces neurite outgrowth from olfactory bulb explants. (A–C) Representative cultures treated as indicated. Treatment with rβNΔC or full-length rβN proteins increases the number of neurites produced by the explants. (D) Quantification of data obtained on neurite outgrowth; the total length of all neurites produced by explants is given here (Sum Length). Protein additions are noted below the bars; the line indicates that cultures were treated identically; the concentrations of protein additions are noted below the line. β-Netrin conventions are as above; 14 nM + AB indicates the simultaneous addition of 14 nM βN and pooled polyclonal antisera to βN. γ2SA denotes the short arm of the laminin γ2 chain; similar conventions are used for γ3 and β2 chains. * Statistically significant difference versus control; # statistically significant difference versus 14 nM βN or 9 nM γ3SA, respectively; P < 0.05.
Mentions: Because of the similarity in structure of β-netrin to netrins 1–3, and because β-netrin expression was detected in the output pathways of the olfactory bulb and the retina, we tested the ability of β-netrin to promote neurite outgrowth. Explants of E15 rat olfactory bulb were dissected, embedded in collagen gels, and incubated with soluble recombinant full-length and truncated β-netrin (rβ-N and rβ-NΔC; Fig. 10). In control cultures, neurites extend around the circumference of the explant (Fig. 10 A). Treatment with rβ-netrin increases both the neurite length and the number of neurites extending from cultures (Fig. 10B and Fig. C). We measured several parameters of this increase in neurite outgrowth including the following: total number of neurites; average neurite length; total length of neurites (sum neurite length); and total neurite area (Table ). By all measures, the addition of rβ-N produced an increase in neurite outgrowth; these data are shown graphically in Fig. 10. With the addition of rβ-N, there was a dose-dependent increase in both the sum length of all neurites and the number of neurites (normalized to explant circumference) of up to 400% of control measurements (Fig. 10D and Fig. E, Fig. rβ-N); values in the presence of all but the lowest concentration of rβ-N were statistically different from control values (P < 0.05). The addition of an affinity-purified preparation of pooled anti–β-netrin antisera antagonized this effect, reducing neurite length and number to control levels.

Bottom Line: In addition, beta-netrin is expressed in a limited set of fiber tracts within the brain, including the lateral olfactory tract and the vomeronasal nerve.Functional studies were performed and show that beta-netrin promotes neurite elongation from olfactory bulb explants.Together, these data suggest that beta-netrin is important in neural, kidney, and vascular development.

View Article: PubMed Central - PubMed

Affiliation: Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.

ABSTRACT
The netrins are a family of laminin-related molecules. Here, we characterize a new member of the family, beta-netrin. beta-Netrin is homologous to the NH(2) terminus of laminin chain short arms; it contains a laminin-like domain VI and 3.5 laminin EGF repeats and a netrin C domain. Unlike other netrins, this new netrin is more related to the laminin beta chains, thus, its name beta-netrin. An initial analysis of the tissue distribution revealed that kidney, heart, ovary, retina, and the olfactory bulb were tissues of high expression. We have expressed the molecule in a eukaryotic cell expression system and made antibodies to the expressed product. Both in situ hybridization and immunohistochemistry were used to describe the cellular source of beta-netrin and where beta-netrin is deposited. beta-Netrin is a basement membrane component; it is present in the basement membranes of the vasculature, kidney, and ovaries. In addition, beta-netrin is expressed in a limited set of fiber tracts within the brain, including the lateral olfactory tract and the vomeronasal nerve. Functional studies were performed and show that beta-netrin promotes neurite elongation from olfactory bulb explants. Together, these data suggest that beta-netrin is important in neural, kidney, and vascular development.

Show MeSH
Related in: MedlinePlus