Protein tyrosine phosphatases ε and α perform nonredundant roles in osteoclasts.
Female mice lacking protein tyrosine phosphatase ε (PTP ε) are mildly osteopetrotic. Osteoclasts from these mice resorb bone matrix poorly, and the structure, stability, and cellular organization of their podosomal adhesion structures are abnormal. Here we compare the role of PTP ε with that of the closely related PTP α in osteoclasts. We show that bone mass and bone production and resorption, as well as production, structure, function, and podosome organization of osteoclasts, are unchanged in mice lacking PTP α. The varying effects of either PTP on podosome organization in osteoclasts are caused by their distinct N-termini. Osteoclasts express the receptor-type PTP α (RPTPa), which is absent from podosomes, and the nonreceptor form of PTP ε (cyt-PTPe), which is present in these structures. The presence of the unique 12 N-terminal residues of cyt-PTPe is essential for podosome regulation; attaching this sequence to the catalytic domains of PTP α enables them to function in osteoclasts. Serine 2 within this sequence regulates cyt-PTPe activity and its effects on podosomes. We conclude that PTPs α and ε play distinct roles in osteoclasts and that the N-terminus of cyt-PTPe, in particular serine 2, is critical for its function in these cells.
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
Eynat
E
Finkelshtein
Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115.
Sutada
S
Lotinun
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
Einat
E
Levy-Apter
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
Esther
E
Arman
Hubrecht Institute-Koninklijke Nederlandse Akademie van Wetenschappen and University Medical Center Utrecht, 3584 CX Utrecht, NetherlandsInstitute of Biology Leiden, Leiden University, 2333 BE Leiden, Netherlands.
Jeroen
J
den Hertog
Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115.
Roland
R
Baron
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel ari.elson@weizmann.ac.il.
Ari
A
Elson
D000595:Amino Acid Sequence; D000818:Animals; D024042:Collagen Type I / Q000378:metabolism; D005260:Female; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010010:Osteoclasts / Q000201:enzymology*; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4 / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D013977:Tibia / Q000473:pathology; D019061:src-Family Kinases / Q000378:metabolism
D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D012694:Serine; D019061:src-Family Kinases; C516843:Ptpra protein, mouse; C098067:Ptpre protein, mouse; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4