Proteomics approach to identifying ATP-covalently modified proteins

This study aims to investigate functionally similar proteins based on their capacity to remain bound to ATP under stringent resolving conditions. Using two-dimensional gel electrophoresis and capillary liquid chromatography on-line mass spectrometry, we have identified several mammalian and E. coli proteins that appear to covalently bind ATP. To validate this approach, we obtained commercially purified forms of proteins identified from two-dimensional protein maps and tested their capacity to bind alpha 32P phosphate labeled ATP. This proteomics approach provides an initial screening method of identifying functionally similar proteins for further scrutiny by a more traditional analysis.     

Unusual presentation of choriocarcinoma

Background  

Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain.     

Differential expression level of cytokeratin 8 in cells of the bovine nucleus pulposus complicates the search for specific intervertebral disc cell markers

Introduction  

Development of cell therapies for repairing the intervertebral disc is limited by the lack of a source of healthy human disc cells. Stem cells, particularly mesenchymal stem cells, are seen as a potential source but differentiation strategies are limited by the lack of specific markers that can distinguish disc cells from articular chondrocytes.     

Mass spectrometric analysis of protein histidine phosphorylation

Summary. Protein histidine phosphorylation is now recognized as an important form of post-translational modification. The acid-lability of phosphohistidine has meant that this phosphorylation has not been as well studied as serine/threonine or tyrosine phosphorylation. We show that phosphohistidine and phosphohistidine-containing phosphopeptides derived from proteolytic digestion of phosphohistone H4 are detectable by ESI-MS. We also demonstrate reverse-phase HPLC separation of these phosphopeptides and their detection by MALDI-TOF-MS.     

Frequent Seizures Are Associated with a Network of Gray Matter Atrophy in Temporal Lobe Epilepsy with or without Hippocampal Sclerosis

Objective

Patients with temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) have diffuse subtle gray matter (GM) atrophy detectable by MRI quantification analyses. However, it is not clear whether the etiology and seizure frequency are associated with this atrophy. We aimed to evaluate the occurrence of GM atrophy and the influence of seizure frequency in patients with TLE and either normal MRI (TLE-NL) or MRI signs of HS (TLE-HS).

Methods

We evaluated a group of 172 consecutive patients with unilateral TLE-HS or TLE-NL as defined by hippocampal volumetry and signal quantification (122 TLE-HS and 50 TLE-NL) plus a group of 82 healthy individuals. Voxel-based morphometry was performed with VBM8/SPM8 in 3T MRIs. Patients with up to three complex partial seizures and no generalized tonic-clonic seizures in the previous year were considered to have infrequent seizures. Those who did not fulfill these criteria were considered to have frequent seizures.

Results

Patients with TLE-HS had more pronounced GM atrophy, including the ipsilateral mesial temporal structures, temporal lobe, bilateral thalami and pre/post-central gyri. Patients with TLE-NL had more subtle GM atrophy, including the ipsilateral orbitofrontal cortex, bilateral thalami and pre/post-central gyri. Both TLE-HS and TLE-NL showed increased GM volume in the contralateral pons. TLE-HS patients with frequent seizures had more pronounced GM atrophy in extra-temporal regions than TLE-HS with infrequent seizures. Patients with TLE-NL and infrequent seizures had no detectable GM atrophy. In both TLE-HS and TLE-NL, the duration of epilepsy correlated with GM atrophy in extra-hippocampal regions.

Conclusion

Although a diffuse network GM atrophy occurs in both TLE-HS and TLE-NL, this is strikingly more evident in TLE-HS and in patients with frequent seizures. These findings suggest that neocortical atrophy in TLE is related to the ongoing seizures and epilepsy duration, while thalamic atrophy is more probably related to the original epileptogenic process.     

Histone H4 histidine phosphorylation: kinases, phosphatases, liver regeneration and cancer

Phosphorylation of histone H4 on one or both of its two histidine residues has been known to occur in liver cells for nearly 40?years and has been associated with proliferation of hepatocytes during regeneration of the liver following mechanical damage. More recently, large increases in histone H4 histidine kinase activity have been found to occur associated with proliferation and differentiation of liver progenitor cells following chemical damage that prevents hepatocyte proliferation. In addition, it has been shown this histone H4 histidine kinase activity is elevated nearly 100-fold in human foetal liver and several hundredfold in hepatocellular carcinoma tissue compared with normal adult liver. In the present paper, we review what is currently known about histone H4 histidine phosphorylation, the kinase(s) responsible and the phosphatases capable of catalysing its dephosphorylation, and briefly summarize the techniques used to detect and measure the histidine phosphorylation of histone H4 and the corresponding kinase activity.     

Parallel evolution between aromatase and androgen receptor in the animal kingdom

There are now many known cases of orthologous or unrelated proteinsin different species that have undergone parallel evolutionto satisfy a similar function. However, there are no reportedcases of parallel evolution for proteins that bind a commonligand but have different functions. We focused on two proteinsthat have different functions in steroid hormone biosynthesisand action but bind a common ligand, androgen. The first protein,androgen receptor (AR), is a nuclear hormone receptor and thesecond one, aromatase (cytochrome P450 19 [CYP19]), convertsandrogen to estrogen. We hypothesized that binding of the androgenligand has exerted common selective pressure on both AR andCYP19, resulting in a signature of parallel evolution betweenthese two proteins, though they perform different functions.Consistent with this hypothesis, we found that rates of aminoacid change in AR and CYP19 are strongly correlated across themetazoan phylogeny, whereas no significant correlation was foundin the control set of proteins. Moreover, we inferred that genomictoolkits required for steroid biosynthesis and action were presentin a basal metazoan, cnidarians. The close similarities betweenvertebrate and sea anemone AR and CYP19 suggest a very ancientorigin of their endocrine functions at the base of metazoanevolution. Finally, we found evidence supporting the hypothesisthat the androgen-to-estrogen ratio determines the gonadal sexin all metazoans.