Linker histones (H1) are a family of lysine-rich proteins that bind to or near the point at which DNA enters and exits the nucleosomal core. A number of studies have shown that H1 expression levels are altered in cancer and that variant-specific changes can be observed in different tumor cells. Although several crystal structures are published for core-histone/DNA complex (nucleosome), the location of linker histone and its interactions are poorly understood. This study attempts to answer several questions regarding the interactions of histone H1 with double stranded partner DNA. Preliminary NMR assignments of this protein have been determined. We also investigated the structural changes in histone H1.0 globular domain induced by DNA binding. During the course of this project it was observed that subtle changes in pH could affect NMR spectral quality. We investigated the pH dependence of the protein stability by performing Circular Dichroism (CD) experiments.

Cleaved fragments of the extracellular matrix protein perlecan have been shown to promote neuroprotection and repair after ischemic stroke. The cysteine proteases cathepsin B and L as well as the metalloprotease bone morphogenic protein 1 (BMP-1) are capable of releasing the biologically active C-terminal laminin-like globular domain (LG3) of perlecan. Exercise, a known method of reducing stroke risk and severity, has been shown to increase the expression of some proteases associated with perlecan processing. Using a transient distal middle cerebral artery occlusion (MCAo) model for focal ischemic stroke we show that while 7 days of running only slightly decreased infarct volume, BMP1 and perlecan (HSPG2) RNA expression in skeletal muscle was significantly increased in 3-month-old male wild type C57/BL6 mice. Moreover, elevated levels of BMP1 RNA were still detectable after 3 days of detraining, suggesting a prolonged effect of exercise on BMP1 expression. Levels of LG3 in the blood were below the limit of detection in the current study, however it is likely that a more sensitive method would enable analysis of serum. These preliminary findings suggest that LG3 could be a molecular mediator of neuroprotection afforded by exercise though further studies are required.