The ANKH ΔE490Mutation in Calcium Pyrophosphate Dihydrate Crystal Deposition Disease (CPPDD) Affects Tissue Non-specific Alkaline Phosphatase (TNAP) Activities



John Wang1, Hing Wo Tsui1, Frank Beier2, Kenneth P.H. Pritzker3, Robert D. Inman1, 4, Florence W.L. Tsui* , 1, 4
1 Genetics and Development Division, Toronto Western Research Institute, Canada
2 Department of Physiology and Pharmacology, University of Western Ontario, Canada
3 Pathology and Laboratory Medicine, Mount Sinai Hospital, Canada
4 Department of Immunology, University of Toronto, Canada


Article Metrics

CrossRef Citations:
0
Total Statistics:

Full-Text HTML Views: 686
Abstract HTML Views: 364
PDF Downloads: 139
Total Views/Downloads: 1189
Unique Statistics:

Full-Text HTML Views: 403
Abstract HTML Views: 227
PDF Downloads: 98
Total Views/Downloads: 728



Bentham Science Publishers Ltd.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/), which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.

* Address correspondence to this author at the Toronto Western Hospital, Mc 14-419, 399 Bathurst Street, Toronto, ON M5T 2S8, Canada; Tel 416-603-5012; Fax: 416-603-5745; E-mail: ftsui@uhnres.utoronto.ca


Abstract

ANKH (human homolog of progressive ankylosis) regulates inorganic pyrophosphate (PPi) transport. Dominant ANKH mutations were detected in at least five multiplex families with calcium pyrophosphate dihydrate crystal deposition disease (CPPPD). The objective of this study is to assess the functional consequences of one CPPDD-associated ANKH mutation (ΔE490) in chondrogenic ATDC5 cells. Stable ATDC5 transfectants bearing myc-tagged constructs of wild-type ANKH, mutant ANKH (ΔE490) and neo controls were generated. Upon ITS (insulin, transferrin and selenium) induction, expression of chondrocyte markers including alkaline phosphatase activity in the various transfectants was assessed. The ANKH ΔE490- transfectants had low alkaline phosphatase activities throughout ITS treatment due to lower TNAP protein expression and the presence of intracellular low-molecular-weight inhibitors. Our results suggest that the interplay of ANKH and TNAP activities is tightly regulated.