Fatty acid-related modulations of membrane fluidity in cells: detection and implications.

Metabolic homeostasis of fatty acids is complex and well-regulated in all organisms. The biosynthesis of saturated fatty acids (SFA) in mammals provides substrates for ß-oxidation and ATP production. Monounsaturated fatty acids (MUFA) are products of desaturases that introduce a methylene group in cis geometry in SFA. Polyunsaturated fatty acids (n-6 and n-3 PUFA) are products of elongation and desaturation of the essential linoleic acid and α-linolenic acid, respectively. The liver processes dietary fatty acids and exports them in lipoproteins for distribution and storage in peripheral tissues. The three types of fatty acids are integrated in membrane phospholipids and determine their biophysical properties and functions. This study was aimed at investigating effects of fatty acids on membrane biophysical properties under varying nutritional and pathological conditions, by integrating lipidomic analysis of membrane phospholipids with functional two-photon microscopy (fTPM) of cellular membranes. This approach was applied to two case studies: first, pancreatic beta-cells, to investigate hormetic and detrimental effects of lipids. Second, red blood cells extracted from a genetic mouse model defective in lipoproteins, to understand the role of lipids in hepatic diseases and metabolic syndrome and their effect on circulating cells.

Hyaluronan synthases and hyaluronidases in nasal polyps.

Nasal polyps (NPs) are benign lesions of nasal and paranasal sinuses mucosa affecting 1-4 % of all adults. Nasal polyposis affects the quality of patient's life as it causes nasal obstruction, postnasal drainage, purulent nasal discharge, hyposmia or anosmia, chronic sinusitis, facial pain and snoring. Without treatment, the disease can alter the craniofacial skeleton in cases of extended growth of polyps. The development of NPs is caused by the hyperplasia of nasal or paranasal sinuses mucosa, and edema of extracellular matrix. This is usually the result of high concentration of high molecular mass hyaluronan (HA) which is either overproduced or accumulated from blood supply. The size of HA presents high diversity and, especially in pathologic conditions, chains of low molecular mass can be observed. In NPs, chains of about 200 kDa have been identified and considered to be responsible for the inflammation. The purpose of the present study was the investigation, in NPs and normal nasal mucosa (NM), of the expression of the wild-type and alternatively spliced forms of hyaluronidases, their immunolocalization, and the expression of HA synthases to examine the isoform(s) responsible for the increased amounts of HA in NPs. Hyaluronidases' presence was examined on mRNA (RT-PCR analysis) and protein (immunohistochemistry) levels. Hyaluronan synthases' presence was examined on mRNA levels. Hyaluronidases were localized in the cytoplasm of epithelial and inflammatory cells, as well as in the matrix. On mRNA level, it was found that hyal-1-wt was decreased in NPs compared to NM and hyal-1-v3, -v4 and -v5 were substantially increased. Moreover, HAS2 and HAS3 were the only hyaluronan synthases detected, the expression of which was almost similar in NPs and NM. Overall, the results of the present study support that hyaluronidases are the main enzymes responsible for the decreased size of hyaluronan observed in NPs; thus they behave as inflammatory agents. Therefore, they could be a potential target for the design of a more advanced treatment for nasal polyposis.

Expression and distribution of aggrecanases in human larynx: ADAMTS-5/aggrecanase-2 is the main aggrecanase in laryngeal carcinoma.

Members of the ADAMTS family of proteases degrade proteoglycans and thereby have the potential to alter tissue architecture and regulate cellular functions. Aggrecanases are the main enzymes responsible for aggrecan degradation, due to their specific cleavage pattern. In this study, the expression status, the macromolecular organization and localization of ADAMTS-1, ADAMTS-4/aggrecanase-1 and ADAMTS-5/aggrecanase-2 in human normal larynx and laryngeal squamous cell carcinoma (LSCC) were investigated. On mRNA level, the results showed that ADAMTS-4 was the highest expressed enzyme in normal larynx, whereas ADAMTS-5 was the main aggrecanase in LSCC presenting a stage-related increase up to stage III (8-fold higher expression compared to normal), and thereafter decreased in stage IV. Accordingly, immunohistochemical analysis showed that ADAMTS-5, but not ADAMTS-4, was highly expressed by carcinoma cells. Sequential extraction revealed an altered distribution and organization of multiple molecular forms (latent, activated and fragmented forms) of the enzymes within the cancerous and their corresponding macroscopically normal laryngeal tissues, compared to the normal ones. Importantly, these analyses indicated that critical macromolecular changes occurred from the earliest LSCC stages not only in malignant parts of the tissue but also in areas that were not in proximity to carcinoma cells and appeared otherwise normal. Overall, the results of the present study show that ADAMTS-5/aggrecanase-2 is the main aggrecanase present in laryngeal carcinoma suggesting a critical role for the enzyme in aggrecan degradation and laryngeal tissue destruction during tumor progression.