Heme utilization in the Caenorhabditis elegans hypodermal cells is facilitated by heme-responsive gene-2

J Biol Chem. 2012 Mar 16;287(12):9601-12. doi: 10.1074/jbc.M111.307694. Epub 2012 Feb 2.

Abstract

The roundworm Caenorhabditis elegans is a heme auxotroph that requires the coordinated actions of HRG-1 heme permeases to transport environmental heme into the intestine and HRG-3, a secreted protein, to deliver intestinal heme to other tissues including the embryo. Here we show that heme homeostasis in the extraintestinal hypodermal tissue was facilitated by the transmembrane protein HRG-2. Systemic heme deficiency up-regulated hrg-2 mRNA expression over 200-fold in the main body hypodermal syncytium, hyp 7. HRG-2 is a type I membrane protein that binds heme and localizes to the endoplasmic reticulum and apical plasma membrane. Cytochrome heme profiles are aberrant in HRG-2-deficient worms, a phenotype that was partially suppressed by heme supplementation. A heme-deficient yeast strain, ectopically expressing worm HRG-2, revealed significantly improved growth at submicromolar concentrations of exogenous heme. Taken together, our results implicate HRG-2 as a facilitator of heme utilization in the Caenorhabditis elegans hypodermis and provide a mechanism for the regulation of heme homeostasis in an extraintestinal tissue.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / chemistry
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / chemistry
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Line
  • Heme / metabolism*
  • Hemeproteins / chemistry
  • Hemeproteins / genetics
  • Hemeproteins / metabolism*
  • Humans
  • Molecular Sequence Data
  • Sequence Alignment
  • Subcutaneous Tissue / metabolism*

Substances

  • Caenorhabditis elegans Proteins
  • Hemeproteins
  • hrg-2 protein, C elegans
  • Heme