Cloning and functional characterization of a folate transporter from the nematode Caenorhabditis elegans

Krishnaswamy Balamurugan, Balasubramaniem Ashokkumar, Mustapha Moussaif, Ji Ying Sze, Hamid M. Said

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Two putative orthologs to the human reduced folate carrier (hRFC), folt-1 and folt-2, which share a 40 and 31% identity, respectively, with the hRFC sequence, have been identified in the Caenorhabditis elegans genome. Functional characterization of the open reading frame of the putative folt-1 and folt-2 showed folt-1 to be a specific folate transporter. Transport of folate by folt-1 expressed in a heterologous expression system showed an acidic pH dependence, saturability (apparent Km of 1.23 ± 0.18 μM), a similar degree of inhibition by reduced and substituted folate derivatives, sensitivity to the anti-inflammatory drug sulfasalazine (apparent Ki of 0.13 mM), and inhibition by anion transport inhibitors, e.g., DIDS. Knocking down (silencing) or knocking out the folt-1 gene led to a significant inhibition of folate uptake by intact living C. elegans. We also cloned the 5′-regulatory region of the folt-1 gene and confirmed promoter activity of the construct in vivo in living C. elegans. With the use of the transcriptional fusion construct (i.e., folt-1::GFP), the expression pattern of folt-1 in different tissues of living animal was found to be highest in the pharynx and intestine. Furthermore, folt-1::GFP expression was developmentally and adaptively regulated in vivo. These studies demonstrate for the first time the existence of a specialized folate uptake system in C. elegans that has similar characteristics to the folate uptake process of the human intestine. Thus C. elegans provides a genetically tractable model that can be used to study integrative aspects of the folate uptake process in the context of the whole animal level.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume293
Issue number2
DOIs
StatePublished - Aug 2007
Externally publishedYes

Fingerprint

Folic Acid Transporters
Cloning
Caenorhabditis elegans
Folic Acid
Organism Cloning
Reduced Folate Carrier Protein
Genes
Intestines
Animals
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
Sulfasalazine
Nucleic Acid Regulatory Sequences
Pharynx
Open Reading Frames
Anions
Anti-Inflammatory Agents
Fusion reactions
Genome
Tissue
Derivatives

Keywords

  • Folate transport
  • Integrative transport physiology
  • Transport regulation

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

Cloning and functional characterization of a folate transporter from the nematode Caenorhabditis elegans. / Balamurugan, Krishnaswamy; Ashokkumar, Balasubramaniem; Moussaif, Mustapha; Sze, Ji Ying; Said, Hamid M.

In: American Journal of Physiology - Cell Physiology, Vol. 293, No. 2, 08.2007.

Research output: Contribution to journalArticle

Balamurugan, Krishnaswamy ; Ashokkumar, Balasubramaniem ; Moussaif, Mustapha ; Sze, Ji Ying ; Said, Hamid M. / Cloning and functional characterization of a folate transporter from the nematode Caenorhabditis elegans. In: American Journal of Physiology - Cell Physiology. 2007 ; Vol. 293, No. 2.
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