Expression patterns of chaperone proteins in cerebral cortex of the fetus with Down syndrome: dysregulation of T-complex protein 1.

Chaperone proteins reduce stress-induced denaturation and aggregation of intracellular proteins and exert protective actions by interfering with the stress-induced apoptotic pathway in the neuronal cells. Although many studies have focused on the critical role of chaperones in protein folding and their relevance in protein conformational diseases such as Alzheimer's disease (AD) and prion disease, limited information is available on their expression pattern in AD-related disease, Down Syndrome (DS). In a previous study, we reported differentially expressed molecular chaperone proteins in the brains of adult DS patients. This report demonstrated the relevance of the aberrant expression patterns to biochemical and neuropathological abnormalities in adult DS brain. To investigate whether this aberrant expression patterns already exist in second trimester DS brain, we performed two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-associated laser desorption ionization mass spectroscopy (MALDI-MS) using fetal DS brain. We unambiguously identified and quantified twelve heat shock proteins (HSPs), three glucose regulated proteins (GRPs) and eight T-complex 1 (TCP-1) subunits. Unlike in adult brain with DS, these studies provide evidence for the normal response of most molecular chaperone proteins at the given time point of DS brain development. However, chaperonin protein TCP-1 alpha and beta subunits showed a significant decrease (P < 0.05) in second trimester brain with DS. Comparable response of chaperone proteins in fetal DS brain suggests that not heat-shock induced proteins but rather chaperonin protein TCP-1 may contribute significantly to neuropathogenesis in the early second trimester DS brain. This study extends observations of distinct expression patterns of molecular chaperones in DS brain and we discuss the relevance of aberrant TCP-1 expression patterns to developmental DS brain at the early stage.