Raman spectroscopy and partial least squares analysis in discrimination of peripheral cells affected by Huntington's disease

Abstract

Huntington's disease (HD) is a neurodegenerative disorder caused by trinucleotide CAG (Cytosine–Adenine–Guanine) expansion on the Huntingtin gene (HTT) encoding for the Huntingtin protein (Htt). The protein has been linked in peripheral fibroblasts with dysregulation of cellular components which are part of lipid rafts in plasma membrane sub-domains. Therefore the analysis of the plasma membrane might be a useful diagnostic biomarker for the detection of the presence and possible onset of HD in readily accessible peripheral cells. Here Raman spectroscopy has been used with a chemometric approach in the form of Partial Least Square (PLS) for an initial corroboration that the plasma membrane is indeed a sub-cellular biomarker discriminator for HD identification. Observations were made in the spectral regions from 400 to 1800cm−1 and 2700 to 3200cm−1 with the former region displaying the most significant differences and peak displacement between plasma membranes extracted from HD and control fibroblast cells. The major differences in plasma membrane composition reside in sub-cellular elements putatively associated to cholesterol, phospholipids (mainly phophatidylinositol) as well as proteins containing tyrosine. These findings are indicative of the plasma membrane as an amenable biomarker for HD for further in vitro research with possible applications in vivo models.