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Reduced-folate carrier (RFC) is expressed in placenta and yolk sac, as well as in cells of the developing forebrain, hindbrain, neural tube, craniofacial region, eye, limb buds and heart.

Maddox DM, Manlapat A, Roon P, Prasad P, Ganapathy V, Smith SB - BMC Dev. Biol. (2003)

Bottom Line: Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking.Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy.These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, USA. oxmandm@yahoo.com

ABSTRACT

Background: Folate is essential for cellular proliferation and tissue regeneration. As mammalian cells cannot synthesize folates de novo, tightly regulated cellular uptake processes have evolved to sustain sufficient levels of intracellular tetrahydrofolate cofactors to support biosynthesis of purines, pyrimidines, and some amino acids (serine, methionine). Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking. We utilized in situ hybridization and immunolocalization to determine the developmental distribution of RFC message and protein, respectively.

Results: In the mouse, RFC transcripts and protein are expressed in the E10.0 placenta and yolk sac. In the E9.0 to E11.5 mouse embryo RFC is widely detectable, with intense signal localized to cell populations in the neural tube, craniofacial region, limb buds and heart. During early development, RFC is expressed throughout the eye, but by E12.5, RFC protein becomes localized to the retinal pigment epithelium (RPE).

Conclusions: Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy. The mechanism, however, by which folate supplementation ameliorates the occurrence of developmental defects is unclear. The present work demonstrates that RFC is present in placenta and yolk sac and provides the first evidence that it is expressed in the neural tube, craniofacial region, limb buds and heart during organogenesis. These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

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Immunohistochemical detection of RFC in developing mouse embryos. Panels A and B demonstrate staining for RFC in an E9.0 and E9.5 embryo, respectively. Positive signal is detected throughout the embryo, with the signal being more intense in the optic vesicles, mandible, heart, somites, limb buds and tail bud. At E10.5 (panel C) expression of RFC is present in the aforementioned tissues as well as in the neural tube, nasal pits and developing eye. Control embryos incubated with pre-blocked antibody demonstrated no signal (Panel D). optic vesicle, OV; mandible, M; heart, H; somites, S; limb buds, LB; tail bud, TB; neural tube, NT; nasal pits, NP; developing eye, DE. Scale bar represents 50 μm in A, C, E and F and 100 μm in B and D.
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Figure 3: Immunohistochemical detection of RFC in developing mouse embryos. Panels A and B demonstrate staining for RFC in an E9.0 and E9.5 embryo, respectively. Positive signal is detected throughout the embryo, with the signal being more intense in the optic vesicles, mandible, heart, somites, limb buds and tail bud. At E10.5 (panel C) expression of RFC is present in the aforementioned tissues as well as in the neural tube, nasal pits and developing eye. Control embryos incubated with pre-blocked antibody demonstrated no signal (Panel D). optic vesicle, OV; mandible, M; heart, H; somites, S; limb buds, LB; tail bud, TB; neural tube, NT; nasal pits, NP; developing eye, DE. Scale bar represents 50 μm in A, C, E and F and 100 μm in B and D.

Mentions: The distribution pattern of RFC protein in E9.0 through E10.5 ICR mouse embryos was determined by whole-mount immunohistochemical localization. Positive signal was ubiquitously present, but at E9.0 the signal was most intense in the optic vesicles, forebrain, mandible, heart, somites and tail bud (Figure 3A). At E9.5 RFC protein was detectable in the developing limb buds (Figure 3B) and by E10.5, besides being present in the developing eye, forebrain, hindbrain, somites, mandible, heart and limb buds, RFC was detectable also in the neural tube and nasal pits (Figure 3C). Control experiments in which tissues were incubated with pre-blocked primary antibody exhibited little background staining (Figure 3D).


Reduced-folate carrier (RFC) is expressed in placenta and yolk sac, as well as in cells of the developing forebrain, hindbrain, neural tube, craniofacial region, eye, limb buds and heart.

Maddox DM, Manlapat A, Roon P, Prasad P, Ganapathy V, Smith SB - BMC Dev. Biol. (2003)

Immunohistochemical detection of RFC in developing mouse embryos. Panels A and B demonstrate staining for RFC in an E9.0 and E9.5 embryo, respectively. Positive signal is detected throughout the embryo, with the signal being more intense in the optic vesicles, mandible, heart, somites, limb buds and tail bud. At E10.5 (panel C) expression of RFC is present in the aforementioned tissues as well as in the neural tube, nasal pits and developing eye. Control embryos incubated with pre-blocked antibody demonstrated no signal (Panel D). optic vesicle, OV; mandible, M; heart, H; somites, S; limb buds, LB; tail bud, TB; neural tube, NT; nasal pits, NP; developing eye, DE. Scale bar represents 50 μm in A, C, E and F and 100 μm in B and D.
© Copyright Policy
Related In: Results  -  Collection

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Figure 3: Immunohistochemical detection of RFC in developing mouse embryos. Panels A and B demonstrate staining for RFC in an E9.0 and E9.5 embryo, respectively. Positive signal is detected throughout the embryo, with the signal being more intense in the optic vesicles, mandible, heart, somites, limb buds and tail bud. At E10.5 (panel C) expression of RFC is present in the aforementioned tissues as well as in the neural tube, nasal pits and developing eye. Control embryos incubated with pre-blocked antibody demonstrated no signal (Panel D). optic vesicle, OV; mandible, M; heart, H; somites, S; limb buds, LB; tail bud, TB; neural tube, NT; nasal pits, NP; developing eye, DE. Scale bar represents 50 μm in A, C, E and F and 100 μm in B and D.
Mentions: The distribution pattern of RFC protein in E9.0 through E10.5 ICR mouse embryos was determined by whole-mount immunohistochemical localization. Positive signal was ubiquitously present, but at E9.0 the signal was most intense in the optic vesicles, forebrain, mandible, heart, somites and tail bud (Figure 3A). At E9.5 RFC protein was detectable in the developing limb buds (Figure 3B) and by E10.5, besides being present in the developing eye, forebrain, hindbrain, somites, mandible, heart and limb buds, RFC was detectable also in the neural tube and nasal pits (Figure 3C). Control experiments in which tissues were incubated with pre-blocked primary antibody exhibited little background staining (Figure 3D).

Bottom Line: Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking.Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy.These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, USA. oxmandm@yahoo.com

ABSTRACT

Background: Folate is essential for cellular proliferation and tissue regeneration. As mammalian cells cannot synthesize folates de novo, tightly regulated cellular uptake processes have evolved to sustain sufficient levels of intracellular tetrahydrofolate cofactors to support biosynthesis of purines, pyrimidines, and some amino acids (serine, methionine). Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking. We utilized in situ hybridization and immunolocalization to determine the developmental distribution of RFC message and protein, respectively.

Results: In the mouse, RFC transcripts and protein are expressed in the E10.0 placenta and yolk sac. In the E9.0 to E11.5 mouse embryo RFC is widely detectable, with intense signal localized to cell populations in the neural tube, craniofacial region, limb buds and heart. During early development, RFC is expressed throughout the eye, but by E12.5, RFC protein becomes localized to the retinal pigment epithelium (RPE).

Conclusions: Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy. The mechanism, however, by which folate supplementation ameliorates the occurrence of developmental defects is unclear. The present work demonstrates that RFC is present in placenta and yolk sac and provides the first evidence that it is expressed in the neural tube, craniofacial region, limb buds and heart during organogenesis. These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

Show MeSH
Related in: MedlinePlus