Generation of fatty acids from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/cardiolipin liposomes that stabilize recombinant human serum albumin.

CONTEXT: At elevated temperatures, studies have shown that serum albumin undergoes irreversible changes to its secondary structure. Anionic fatty acids and/or anionic surfactants have been shown to stabilize human serum albumin (HSA) against thermal denaturation through bridging hydrophobic domains and cationic amino acids residues of the protein. OBJECTIVE: As albumin can readily interact with a variety of liposomes, this study proposes that cardiolipin delivered via 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes can improve the thermal stability of recombinant HSA produced in Saccharomyces cerevisiae (ScrHSA) in a similar manner to anionic fatty acids. MATERIALS AND METHODS: Thermal stability and structure of ScrHSA in the absence and presence of DPPC/cardiolipin liposomes was assessed with U/V circular dichroism spectropolarimetry and protein thermal stability was confirmed with differential scanning calorimetry. RESULTS: Although freshly prepared DPPC/cardiolipin liposomes did not improve the stability of ScrHSA, DPPC/cardiolipin liposomes incubated at room temperature for 7 d (7dRT) dramatically improved the thermal stability of the protein. Mass spectrometry analysis identified the presence of fatty acids in the 7dRT liposomes, not identified in freshly prepared liposomes, to which the improved stability was attributed. DISCUSSION AND CONCLUSION: The generation of fatty acids is attributed to either the chemical hydrolysis or oxidative cleavage of the unsaturated acyl chains of cardiolipin. By modulating the lipid composition through the introduction of lipids with higher acyl chain unsaturation, it may be possible to generate the stabilizing fatty acids in a more rapid manner.

Implication of microRNA deregulation in the response of vertebrates to endocrine disrupting chemicals.

Micro ribonucleic acids (miRNAs) are recently discovered small regulatory molecules that control messenger RNA (mRNA) translation in plants and animals and have been implicated in a variety of hormone-related physiological pathways. Estrogens, thyroid hormones, and gonadotropins are all known to act on miRNA abundance to cause major shifts in cellular activity, physiology, and homeostatic control mechanisms. Research on cancer biology has also recently considered miRNA as therapeutic targets, because the deregulation of specific miRNAs in various tissues has been correlated with tumorigenesis and other carcinogenic responses. Because many pharmaceuticals are considered to be endocrine-disrupting chemicals (EDCs), their effects on miRNAs may be important to our understanding of basic physiological control and phenotypic outcomes of wildlife exposed to EDCs. Presented is a brief overview of the synthesis, control, and action of miRNAs, focusing on endocrine systems. The antidepressant fluoxetine will be used as an example for miRNA studies in aquatic species, one of the few examples in ecotoxicology. Given the mounting evidence that miRNAs are regulated by hormones, a clear need exists to investigate the potential for environmental EDCs to deregulate miRNA expression and action.