Ruiz Lab (Hupho group)

Human Phosphate Research Group (Hupho Group)

Contact Information:
Felix A. Ruiz
Hospital Universitario "Puerta de Mar", Unidad de Investigación. 9ª planta,
Avda. Ana de Viya, 21, 11009-Cadiz, SPAIN
Phone: 34-956003156 - Fax: 34-956002347
email: felix.ruiz at - Personal Web Page

Roles and Metabolism of Phosphate Moieties in Human Cells and Tissues

Our group is interested in the study of phosphate moieties in human cells and tissues. More particularly, we are focused in phosphate biopolymers that have been ignored for a long time: inorganic polyphosphates.

Inorganic Polyphosphates

The term “Inorganic polyphosphate” or “polyP” includes linear polymers of orthophosphate residues linked by phosphoanhydride bonds. The biological functions of polyP have been investigated mostly in microorganisms. Unicellular organisms, like algae, bacteria and fungi, use polyP to compensate for drastic environmental changes. In pathogenic bacteria, polyP has been discovered to be a critical feature for virulence. The enzyme responsible for synthesis of polyP, polyphosphate kinase, has been described to be a target for very promising antibiotics.

Scheme of polyP structure. The value for “n” is superior than 1 and could be many hundreds. (Adapted from Kronberg 1999, Prog Mol Subcell Biol. 23:1).

Although the presence of polyP has been demonstrated in the rat tissues, and few human cells lines, little is known regarding the functions of polyP and the effects of polyP on mammalian cells. Therefore, we are interested in the study of polyP roles in the biology of human cells types. In this regard, we have recently described the presence of high concentration of polyp in human platelets. In platelets, polyP is preferentially located in acidic calcium vacuoles known as dense granules.

The picture shows the localization of polyP in human platelets. Platelets were stained with 4’, 6-diamidino-2-phenylindole (DAPI) and checked by confocal laser scanning microscopy. DAPI is a useful tool in the fluorometric analysis of DNA but can also be used to study polyPs. Note the accumulation of DAPI in small organelles.

Current findings of high levels of polyP in platelets dense granules suggested that these organelles are similar to the acidocalcisomes described in other species such as parasites, bacteria, algae, and slime mold.

Related Publications:

Hernández-Ruiz L, Sáez-Benito A, Pujol-Moix N, Rodríguez-Martorell J, Ruiz FA. (2008) Platelet inorganic polyphosphate decreases in patients with delta storage pool disease. J Thromb Haemost. 2008 Nov 25. [Epub ahead of print]

Hernandez-Ruiz L, Valverde F, Jimenez-Nunez MD, Ocana E, Saez-Benito A, Rodriguez-Martorell J, Bohorquez JC, Serrano A, Ruiz FA. (2007) Organellar Proteomics of Human Platelet Dense Granules Reveals That 14-3-3zeta Is a Granule Protein Related to Atherosclerosis. J Proteome Res. Nov;6(11):4449-57.

Hernandez-Ruiz L, Gonzalez-Garcia I, Castro C, Brieva JA, Ruiz FA. (2006) Inorganic polyphosphate and specific induction of apoptosis in human plasma cells. Haematologica. 91(9):1180-6.

Ruiz FA, Lea CR, Oldfield E, Docampo R. (2004) Human platelet dense granules contain polyphosphate and are similar to acidocalcisomes of bacteria and unicellular eukaryotes. J Biol Chem. 279(43):44250-7.

Seufferheld M, Vieira MC, Ruiz FA, Rodrigues CO, Moreno SN, Docampo R. (2003) Identification of organelles in bacteria similar to acidocalcisomes of unicellular eukaryotes. J Biol Chem. 278(32):29971-8

Marchesini N, Ruiz FA, Vieira M, Docampo R. (2002) Acidocalcisomes are functionally linked to the contractile vacuole of Dictyostelium discoideum. J Biol Chem. 277(10):8146-53

Ruiz FA, Marchesini N, Seufferheld M, Govindjee, Docampo R. (2001) The polyphosphate bodies of Chlamydomonas reinhardtii possess a proton pumping pyrophosphatase and are similar to acidocalcisomes. J Biol Chem. 276(49):46196-203

Ruiz FA, Rodriguez CO, Docampo R. (2001) Rapid changes in polyphosphate content within acidocalcisomes in response to cell growth, differentiation and environmental stress in Trypanosoma cruzi. J Biol Chem. 276(28):26114-21.

This page was last updated on December 12, 2008. Please send comments to felix.ruiz at

Powered by