Synergistic activation of p70S6 kinase associated with stem cell factor in MO7e cells

Stem cell factor (SCF) is an early-acting cytokine inducing proliferative synergy with other cytokines in hematopoietic cells. We earlier showed that p21 was synergistically induced in SCF synergy and the p44/42 MAPK pathway was essential for the transcriptional control of p21. SCF synergy accompanies protein synthesis. p70S6K implicated in translational control in many other systems has not been shown in SCF synergy induced system. GM-CSF dependent human cell line MO7e was stimulated with GM-CSF with SCF, and investigated activation of p70S6K by using phospho-specific antibody. A possible contribution of p70S6K to SCF synergy was examined by measuring p21 induction as a model system. p70S6K was slightly activated by GM-CSF alone and markedly activated by SCF alone. Combined stimulation with these two cytokines synergistically activated p70S6K resulting in persistent activation. Addition of the pathway- specific inhibitors for PI3K or FRAP/TOR, two upstream pathways of p70S6K resulted in abolishment of p70S6K phosphorylation and also significant reduction of p21 protein level. These data suggest that synergistically activated p70S6K by GM-CSF plus SCF involves, at least in part, protein translational control including regulation of p21 protein.

Identification rhFKBP12 by ESI-quadrupole-oa-TOF tandem mass spectrometry / 药学学报

<p><b>AIM</b>To identify recombinant protein rhFKBP12 by new technique ESI-quadrupole-oa-TOF tandem mass spectrometry.</p><p><b>METHODS</b>The molecular weight of rhFKBP12 was measured by ESI-MS. Digest rhFKBP12 by trypsin at 37 degrees C over night. The tryptic digested peptides were measured and then two doublely charged peptides were selected to measure their amino acid sequence by ESI-MS/MS. Search database with the measured amino acid sequence to identify rhFKBP12.</p><p><b>RESULTS</b>The calculated molecular weight of rhFKBP12 was 11,819.54 and the measured value was 11,820.38. The measurement percent error was only 0.007%. The sequence measured by ESI-MS/MS was QVETMS and EEGVAQMSV and then the database search results with them were both hFKBP12.</p><p><b>CONCLUSION</b>The study proves that the primary structure of rhFKBP12 is correct and there is no amino acid deletion, mutation and modification in its expression, refolding and purification. It also shows that ESI-MS/MS is a good method to identify protein with advantage of sensitivity, high speed and accuracy.</p>

FKBP-12 Exhibits an Inhibitory Activity on Calcium Oxalate Crystal Growth in Vitro

Urolithiasis and calcium oxalate crystal deposition diseases are still significant medical problems. In the course of nephrocalcin cDNA cloning, we have identified FKBP-12 as an inhibitory molecule of calcium oxalate crystal growth. lambdagt 11 cDNA libraries were constructed from renal carcinoma tissues and screened for nephrocalcin cDNA clones using anti-nephrocalcin antibody as a probe. Clones expressing recombinant proteins, which appeared to be antigenically cross-reactive to nephrocalcin, were isolated and their DNA sequences and inhibitory activities on the calcium oxalate crystal growth were determined. One of the clone lambdagt 11 #31-1 had a partial fragment (80 bp) of FKBP-12 cDNA as an insert. Therefore, a full-length FKBP-12 cDNA was PCR-cloned from the lambdagt 11 renal carcinoma cDNA library and was subcloned into an expression vector. The resultant recombinant FKBP-12 exhibited an inhibitory activity on the calcium oxalate crystal growth (Kd=10(-7) M). Physiological effect of the extracellular FKBP-12 was investigated in terms of macrophage activation and proinflammatory cytokine gene induction. Extracellular FKBP-12 failed to activate macrophages even at high concentrations. FKBP-12 seems an anti-stone molecule for the oxalate crystal deposition disease and recurrent stone diseases.

Molecular Cloning of Mouse FK-506 Binding Protein 12.6 Gene and Its Biological Function and Expression Patterns in the Various Models of Heart Disease

BACKGROUND AND OBJECTIVES: The FK-506 binding protein 12 (FKBP12) regulates intracellular Ca2+ release by stabilizing the Ca2+-induced Ca2+-release channel (ryanodine receptor) in skeletal muscle. It has been recently shown that a different FKBP, FKBP12.6, is specifically associated with cardiac ryanodine receptor. Since the role of FKBP12.6 in excitation-contraction coupling in the cardiac muscle has not been precisely determined, its biological function was assessed and expression patterns of FKBP12.6 were evaluated in the various models of heart disease. MATERIAL AND METHODS: The mouse (m) FKBP12.6 gene was cloned and characterized after screening a mouse genomic DNA library using a mFKBP12.6 cDNA obtained through reverse transcriptase-polymerase chain reaction. Expression levels of mFKBP12.6 was evaluated during cardiac development and in the models of cardiac hypertrophy and failure. RESULTS: Both mFKBP12.6 and mFKBP12 contain an open reading frame of 327 nucleotides encoding 108 amino acids. Comparison of mFKBP12.6 cDNA to rat FKBP12.6, human FKBP12.6 and mFKBP12 cDNA revealed 95%, 94% and 74% identity in nucleotide sequence and 98%, 97% and 80% identity in amino acid sequence, respectively. Purified recombinant mFKBP12.6 migrated slower than either mFKBP12 or human FKBP12 on an SDS-polyacrylamide gel, despite having the same number of amino acids and a slightly lower calculated molecular mass. Northern blot analysis showed that the expression of FKBP12 and FKBP12.6 to be highest in brain. While the expression of FKBP12 was much stronger in adult than in embryonic hearts, it was further increased following pressure overload hypertrophy. FKBP12.6 mRNA expression analyzed by RNase protection assay was upregulated after induction of cardiac hypertrophy like FKBP12, whereas it was decreased in the failing heart. The mFKBP12.6 gene contains 5 exons and the proteincoding region of the gene was divided into 4 exon modules. CONCLUSION: We report the molecular cloning and characterization of the mouse FKBP12.6 gene. According to these results, FKBP12 and FKBP12.6 may play a role in the development of cardiac hypertrophy and transition to heart failure. To precisely determine the role of FKBP12 and FKBP12.6 in the heart, a strategy using homologous recombination in embryonic stem cells to conditionally ablate exon 2 of mFKBP12.6 gene has been developed and initial characterization is now underway.