Project description:Uromodulin (Tamm-Horsfall protein, THP) is a glycoprotein uniquely produced in the kidney. It is released by cells of the thick ascending limbs (TAL) apically in the urine, and basolaterally in the renal interstitium and systemic circulation. Processing of mature urinary THP, which polymerizes into supra-molecular filaments, requires cleavage of an external hydrophobic patch (EHP) at the C terminus. However, THP in the circulation is not polymerized, and it remains unclear if non-aggregated forms of THP exist natively in the urine. We propose that an alternative processing path, which retains the EHP domain, can lead to a non-polymerizing form of THP. We generated an antibody that specifically recognizes THP with retained EHP (THP+EHP) and established its presence in the urine in a non-polymerized native state. Proteomic characterization of urinary THP+EHP revealed its C-terminus to end at F617. In the human kidney, THP+EHP was not only detected in TAL cells, but also diffusely in the renal parenchyma. Using C-terminus proteomic sequencing and immunoblotting, we then demonstrated that serum THP has also retained EHP. In a small cohort of patients at risk for acute kidney injury (AKI), admission urinary THP+EHP was significantly lower in patients who subsequently developed AKI during hospitalization. Our findings uncover novel insights into uromodulin biology by establishing the presence of an alternative path for cellular processing, which could explain the release of non-polymerizing THP in the circulation. Larger studies as needed to establish the utility of urinary THP+EHP as a sensitive biomarker of kidney health and susceptibility to injury.
Project description:Brain slice cultures offer advantages over other in vitro methods, as they mimic numerous in vivo aspects. For most purposes, slices of the developing brain, termed organotypic slice cultures , preserve a high degree of cellular differentiation and tissue organization. The entorhino-hippocampal connection (EHP) is the main entrance of information to the hippocampus proper and the dentate gyrus. Also it has some specific features that make them particularly interesting in studies of axonal regeneration: (i) the culture method obviates the need for extensive animal surgery and requires less time than other in vivo approaches; (ii) the EHP is reproduced easily in vitro in cultures with a degree of laminar specificity similar to that found in vivo; (iii) the EHP is myelinated both in vitro and in vivo; and (iv) most of the cellular and molecular barriers to axon regeneration are present after the axotomy of the EHP in vitro. Altogether this model is useful to evaluate axon regeneration and putative estrategies to promote axonal growth. Keywords: organotypic slice cultures; axonal lession; gene expression To evaluate the genes whose transcription was regulated after 1, 3 and 7 days after EHP (Entorhino-Hippocampal Pathway) axotomy, RNA samples were analyzed with Agilent whole genome rat long oligonucleotide (44 K base) probe based microarrays.
Project description:Brain slice cultures offer advantages over other in vitro methods, as they mimic numerous in vivo aspects. For most purposes, slices of the developing brain, termed organotypic slice cultures , preserve a high degree of cellular differentiation and tissue organization. The entorhino-hippocampal connection (EHP) is the main entrance of information to the hippocampus proper and the dentate gyrus. Also it has some specific features that make them particularly interesting in studies of axonal regeneration: (i) the culture method obviates the need for extensive animal surgery and requires less time than other in vivo approaches; (ii) the EHP is reproduced easily in vitro in cultures with a degree of laminar specificity similar to that found in vivo; (iii) the EHP is myelinated both in vitro and in vivo; and (iv) most of the cellular and molecular barriers to axon regeneration are present after the axotomy of the EHP in vitro. Altogether this model is useful to evaluate axon regeneration and putative estrategies to promote axonal growth. Keywords: organotypic slice cultures; axonal lession; gene expression