A SLC4 family bicarbonate transporter is critical for intracellular pH regulation and biomineralization in sea urchin embryos

Elife. 2018 May 1;7:e36600. doi: 10.7554/eLife.36600.


Efficient pH regulation is a fundamental requisite of all calcifying systems in animals and plants but with the underlying pH regulatory mechanisms remaining largely unknown. Using the sea urchin larva, this work identified the SLC4 HCO3- transporter family member SpSlc4a10 to be critically involved in the formation of an elaborate calcitic endoskeleton. SpSlc4a10 is specifically expressed by calcifying primary mesenchyme cells with peak expression during de novo formation of the skeleton. Knock-down of SpSlc4a10 led to pH regulatory defects accompanied by decreased calcification rates and skeleton deformations. Reductions in seawater pH, resembling ocean acidification scenarios, led to an increase in SpSlc4a10 expression suggesting a compensatory mechanism in place to maintain calcification rates. We propose a first pH regulatory and HCO3- concentrating mechanism that is fundamentally linked to the biological precipitation of CaCO3. This knowledge will help understanding biomineralization strategies in animals and their interaction with a changing environment.

Keywords: Na+/HCO3- cotransporter; Strongylocentrotus purpuratus; calcification; ecology; larval skeleton; ocean acidification; primary mesenchyme cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bicarbonates / metabolism*
  • Biomineralization*
  • Calcification, Physiologic
  • Calcium / metabolism
  • Carbon Dioxide / metabolism
  • Embryo, Nonmammalian / cytology
  • Embryo, Nonmammalian / physiology*
  • Hydrogen-Ion Concentration
  • Larva / metabolism
  • Phylogeny
  • Sea Urchins / embryology
  • Sea Urchins / physiology*
  • Sodium-Bicarbonate Symporters / genetics
  • Sodium-Bicarbonate Symporters / metabolism*


  • Bicarbonates
  • Sodium-Bicarbonate Symporters
  • Carbon Dioxide
  • Calcium

Grant support

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.