Learning about genomics and disease from the anucleate human red blood cell

Lipid transport proteins in malaria, from Plasmodium parasites to their hosts

Eukaryotic unicellular pathogens from the genus Plasmodium are the etiological agents of malaria, a disease that persists over a wide range of vertebrate species, including humans. During its dynamic lifecycle, survival in the different hosts depends on the parasite's ability to establish a suitable environmental milieu. To achieve this, specific host processes are exploited to support optimal growth, including extensive modifications to the infected host cell. These modifications include the formation of novel membranous structures, which are induced by the parasite. Consequently, to maintain a finely tuned and dynamic lipid environment, the organisation and distribution of lipids to different cell sites likely requires specialised lipid transfer proteins (LTPs). Indeed, several parasite and host-derived LTPs have been identified and shown to be essential at specific stages. Here we describe the roles of LTPs in parasite development and adaptation to its host including how the latest studies are profiting from the improved genetic, lipidomic and imaging toolkits available to study Plasmodium parasites. Lastly, a list of predicted Plasmodium LTPs is provided to encourage research in this field.

Modulation of L-Arginine-Arginase Metabolic Pathway Enzymes: Immunocytochemistry and mRNA Expression in Peripheral Blood and Tissue Levels in Head and Neck Squamous Cell Carcinomas in North East India

BACKGROUND

Arginine may play important roles in tumor progression by providing ornithine for polyamine biosynthesis, required for cell growth. The aim of this work was to determine the expression of arginine metabolic pathway enzymes in head and neck squamous cell carcinoma (HNSCC) in northeast India.

MATERIALS AND METHODS

The expressions of arginase isoforms (ARG1 and ARG2), ornithine aminotransferase (OAT) and ornithine decarboxylase (ODC) were examined in fifty paired HNSCC and adjacent non-tumor tissues by immunohistochemistry. Immunocytochemistry, semiquantitative reverse transcription sq-PCR and quantitative real-time qPCR were used to assess protein and mRNA expressions in peripheral blood of fifty HNSCC patients and hundred controls.

RESULTS

ARG1 and ODC protein and mRNA were strongly expressed in peripheral blood from HNSCC patients. No ARG2 expression was observed. In vivo, expression of ARG1, ARG2 and ODC was significantly higher in tumor than in non-tumor tissues. Most tumors expressed low levels of OAT, with no difference in tissues or blood, compared to controls. The absolute extent of maximal ARG1 upregulation with qPCR showed 6.23 fold increase in HNSCC.

CONCLUSIONS

These findings strongly suggest that in HNSCCs, the ARG1 pathway is stimulated leading to the formation of polyamines as indicated by higher ODC expression, which promote tumor growth.

Chromatin boundaries require functional collaboration between the hSET1 and NURF complexes

Chromatin insulators protect erythroid genes from being silenced during erythropoiesis, and the disruption of barrier insulator function in erythroid membrane gene loci results in mild or severe anemia. We showed previously that the USF1/2-bound 5'HS4 insulator mediates chromatin barrier activity in the erythroid-specific chicken β-globin locus. It is currently not known how insulators establish such a barrier. To understand the function of USF1, we purified USF1-associated protein complexes and found that USF1 forms a multiprotein complex with hSET1 and NURF, thus exhibiting histone H3K4 methyltransferase- and ATP-dependent nucleosome remodeling activities, respectively. Both SET1 and NURF are recruited to the 5'HS4 insulator by USF1 to retain the active chromatin structure in erythrocytes. Knock-down of NURF resulted in a rapid loss of barrier activity accompanied by an alteration of nucleosome positioning, increased occupancy of the nucleosome-free linker region at the insulator site, and increased repressive H3K27me3 levels in the vicinity of the HS4 insulator. Furthermore, suppression of SET1 reduced barrier activity, decreased H3K4me2 and acH3K9/K14, and diminished the recruitment of BPTF at several erythroid-specific barrier insulator sites. Therefore, our data reveal a synergistic role of hSET1 and NURF in regulating the USF-bound barrier insulator to prevent erythroid genes from encroachment of heterochromatin.