RESUMEN
Chaperones safeguard protein homeostasis by promoting folding and preventing aggregation. HSP110 is a cytosolic chaperone that functions as a nucleotide exchange factor for the HSP70 cycle. Together with HSP70 and a J-domain protein (JDP), HSP110 maintains protein folding and resolubilizes aggregates. Interestingly, HSP110 is vital for the HSP70/110/JDP-mediated disaggregation of amyloidogenic proteins implicated in neurodegenerative diseases (i.e., α-synuclein, HTT, and tau). However, despite its abundance, HSP110 remains still an enigmatic chaperone, and its functional spectrum is not very well understood. Of note, the disaggregation activity of neurodegenerative disease-associated amyloid fibrils showed both beneficial and detrimental outcomes in vivo. To gain a more comprehensive understanding of the chaperone HSP110 in vivo, we analyzed its role in neuronal proteostasis and neurodegeneration in C. elegans. Specifically, we investigated the role of HSP110 in the regulation of amyloid beta peptide (Aß) aggregation using an established Aß-C. elegans model that mimics Alzheimer's disease pathology. We generated a novel C. elegans model that over-expresses hsp-110 pan-neuronally, and we also depleted hsp-110 by RNAi-mediated knockdown. We assessed Aß aggregation in vivo and in situ by fluorescence lifetime imaging. We found that hsp-110 over-expression exacerbated Aß aggregation and appeared to reduce the conformational variability of the Aß aggregates, whereas hsp-110 depletion reduced aggregation more significantly in the IL2 neurons, which marked the onset of Aß aggregation. HSP-110 also plays a central role in growth and fertility as its over-expression compromises nematode physiology. In addition, we found that HSP-110 modulation affects the autophagy pathway. While hsp-110 over-expression impairs the autophagic flux, a depletion enhances it. Thus, HSP-110 regulates multiple nodes of the proteostasis network to control amyloid protein aggregation, disaggregation, and autophagic clearance.
RESUMEN
Matrix metalloproteinases (MMP) are a family of more than 25 zinc-dependent enzymes that are centrally involved in cellular migration, tissue remodeling, cancer invasion and metastasis. Besides degrading extracellular matrix proteins, MMPs are crucial for growth factor and cytokine release and activation. At the same time, they can inactivate inflammatory mediators and enzymes themselves through protein degradation. Subclasses of MMPs include collagenases, gelatinases, stromelysins, membrane-bound MMPs, and others. With regard to the stromelysin subfamily, three members exist, e.g., stromelysin-1 (MMP-3), stromelysin-2 (MMP-10), and stromelysin-3 (MMP-11). MMP-3, and MMP-10 share extensive similarities at the amino acid level that made it difficult to develop specific antibodies distinguishing between MMP-3 and MMP-10. Scrutinizing published data on and performing different analyses with detection of both stromelysins with commercially available or lab-made antibodies showed ambiguous results with regard to specificity of antibodies used to date. We developed new specific antibodies against the most divergent parts of the active forms of both proteins. We assessed the specificity of our novel specific anti-human and anti-mouse MMP-3 and MMP-10 antibodies in cell lysates and different human and murine skin tissues. Tests analyzing specificity of the novel antibodies included Western immunoblotting, immunofluorescence, and immunohistochemistry on paraffin sections. Analyses demonstrated specific detection of respective protein for human or mouse samples except for the anti-human MMP-3 antibody. The aim of this summary was to call attention the MMP research community to distinguish clearly between both enzymes. Our new specific anti-mouse MMP-3 and both MMP-10 antibodies allow us to address this detection problem and to enable comparative studies between both stromelysins with regard to their respective location and function in the tissue.
