We conjecture some spontaneous protective mechnisms may be activated to inhibit this process

ab7 and rabbit anti-NFAT2 were purchased from Cell Signaling Technology. Rabbit anti-cathepsin K was a gift from Dr. Eunice Lee, Shriners Hospital for Children, Montreal, Canada; rabbit anti-TRAP was a gift from Dr. Gran Andersson, Karolinska Institutet, Stockholm, Sweden; rabbit anti-a3-vATPase was a gift from Dr. Beth Lee, Ohio State University, Columbus, OH. Anti-Plekhm1 antibody was raised in rabbits against the N-terminal 497 amino acids of human Plekhm1 protein using a standard PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19667322 immunization protocol, PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19666584 and the antiserum was affinity purified against the immunizing protein using UltraLink Biosupport resin. Anti-TRAFD1 antibody was raised in chicken against whole affinity purified human TRAFD1 protein using a standard immunization protocol. IgY was precipitated from egg yolk and affinity purified with the immunizing antigen using Ultra Link Iodoacetyl Gel resin according to the manufacturer’s protocol. Secondary HRP-conjugated antibodies used for immunoblotting were: goat anti-rabbit IgG and rabbit anti-goat IgG, sheep anti-mouse IgG, and donkey anti-chicken IgY. Secondary fluorescent dye-conjugated antibodies used for immunofluorescence: donkey anti-chicken IgY, Alexa 488 and TRITC, donkey anti-goat IgG, Alexa 488, and donkey anti-rabbit IgG, Alexa 568, purchased from Jackson ImmunoResearch Laboratories Inc.. Donkey anti-rabbit IgG, Alexa 488 was from Life Technologies. 3 / 21 TRAFD1 in Osteoclast Activity Cell cultures RAW264.7 and HEK 293 cells were maintained in -minimum essential medium or Dulbecco’s modified Eagle’s medium, respectively, supplemented with 10% FBS, 1% penicillin/streptomycin in a humidified incubator at 37C in 5% CO2. Bone marrow mononuclear cells and splenocytes were collected from mice and rats as described previously.Viral infections of RAW264.7 cells were carried out at a multiplicity of infection of 1 with 8 g/ml of hexadimethrine bromide. To obtain stable cell lines with TRAFD1 knocked down, colonies of virally transduced RAW264.7 cells were selected by culturing in medium containing 3 g/ml of puromycin. Cells were routinely maintained in 1 g/ml puromycin. Knock down efficiency was confirmed using RT-qPCR with gene expression normalized to acidic ribosomal phosphoprotein P0 . Tandem-affinity purification and mass spectrometry The pIRES-puro Glue vector, generated by Angers et al.,, was purchased from Addgene. Full-length cDNA for human Plekhm1 was amplified and 1268798 cloned into the pIRES-puro Glue vector downstream of the dual affinity tag. Construct sequences were verified by sequencing. The purification procedure was described previously. Briefly, cell lysate from HEK293 cells stably expressing low levels of TAP-tagged Plekhm1 was incubated overnight at 4C with 100 l packed volume of Streptavidin Sepharose. Streptavidin beads were washed and protein complexes were eluted from the streptavidin resin in calmodulin binding buffer supplemented with 50 mM biotin. The second round of affinity purification was performed using 100 l of Calmodulin Sepharose. After washing, the protein complexes were eluted twice with 100 l wash buffer containing EGTA. The eluates were combined, run briefly into an SDS-PAGE gel, excised, and sent to the Proteomic and Mass Spectrometry Facility at University of Massachusetts Medical School to be digested with trypsin and analyzed by LC-MS/MS. 4 / 21 TRAFD1 in Osteoclast Activity Immunoprecipitation/pull down Full-length human cDNA for Plekhm1 and various deletion mutants were PCR-amplifi