A novel annexin A2 protein with platelet aggregation-inhibiting activity from amphibian Bombina maxima skin

Proteins from toad's parotoid macroglands: do they play a role in gland functioning and chemical defence?

BACKGROUND

Parotoid gland secretion of bufonid toads is a rich source of toxic molecules that are used against predators, parasites and pathogens. Bufadienolides and biogenic amines are the principal compounds responsible for toxicity of parotoid secretion. Many toxicological and pharmacological analyses of parotoid secretions have been performed, but little is known about the processes related to poison production and secretion. Therefore, our aim was to investigate protein content in parotoids of the common toad, Bufo bufo, to understand the processes that regulate synthesis and excretion of toxins as well as functioning of parotoid macroglands.

RESULTS

Applying a proteomic approach we identified 162 proteins in the extract from toad's parotoids that were classified into 11 categories of biological functions. One-third (34.6%) of the identified molecules, including acyl-CoA-binding protein, actin, catalase, calmodulin, and enolases, were involved in cell metabolism. We found many proteins related to cell division and cell cycle regulation (12.0%; e.g. histone and tubulin), cell structure maintenance (8.4%; e.g. thymosin beta-4, tubulin), intra- and extracellular transport (8.4%), cell aging and apoptosis (7.3%; e.g. catalase and pyruvate kinase) as well as immune (7.0%; e.g. interleukin-24 and UV excision repair protein) and stress (6.3%; including heat shock proteins, peroxiredoxin-6 and superoxide dismutase) response. We also identified two proteins, phosphomevalonate kinase and isopentenyl-diphosphate delta-isomerase 1, that are involved in synthesis of cholesterol which is a precursor for bufadienolides biosynthesis. STRING protein-protein interaction network predicted for identified proteins showed that most proteins are related to metabolic processes, particularly glycolysis, stress response and DNA repair and replication. The results of GO enrichment and KEGG analyses are also consistent with these findings.

CONCLUSION

This finding indicates that cholesterol may be synthesized in parotoids, and not only in the liver from which is then transferred through the bloodstream to the parotoid macroglands. Presence of proteins that regulate cell cycle, cell division, aging and apoptosis may indicate a high epithelial cell turnover in parotoids. Proteins protecting skin cells from DNA damage may help to minimize the harmful effects of UV radiation. Thus, our work extends our knowledge with new and important functions of parotoids, major glands involved in the bufonid chemical defence.

Hematological manifestations of antiphospholipid syndrome: Going beyond thrombosis

Thrombotic complications are a hallmark of antiphospholipid syndrome (APS). These vascular - arterial, venous, and/or small vessel - complications are well described and known to hematologists and healthcare providers caring for patients with this disease. In this review, we shed light on other hematological manifestations of the disease, including bleeding, thrombocytopenia, autoimmune hemolytic anemia, and thrombotic microangiopathy syndromes. While these manifestations are not bona fide clinical criteria for the diagnosis of APS, they frequently interact and contribute to the complexity of clinical management of APS.

Significance of expression of PKCα, Annexin A2 and S100A10 proteins in gastric cancer

AIM: To investigate the clinical significance of expression of protein kinase C (PKC), Annexin A2 and S100A10 proteins in gastric cancer and provide valuable data for finding diagnosis related proteins in gastric cancer.

METHODS: The expression of PKCα, Annexin A2 and S100A10 proteins was detected by Western blot in normal gastric mucosa and gastric cancer tissues. Moreover, their expression was analyzed by immunohistochemistry in a tissue array containing normal gastric mucosa and gastric cancer tissues. The clinicopathologic significance of their expression was evaluated.

RESULTS: Western blot analysis showed that the expression of PKCα, Annexin A2 and S100A10 proteins was significantly higher in gastric cancer tissue than in normal gastric mucosa tissue (P < 0.01 for all). Immunohistochemistry analysis showed that the positive expression rates of PKCα, Annexin A2 and S100A10 proteins were significantly lower in normal gastric mucosa tissue than in gastric cancer tissue [8.82% (3/34) vs 76.54% (62/81), 5.88% (2/34) vs 79.01% (64/81), 2.94% (1/34) vs 59.26% (48/81); P < 0.01 for all].

CONCLUSION: The expression of PKCα, Annexin A2 and S100A10 proteins is up-regulated in gastric cancer tissue compared with normal gastric mucosa tissue and may be related with the occurrence and differentiation degree of gastric cancer.