Smaldone, G. | Search bioRxiv

bioRxiv2024

Comparative Analysis of Stain-Free Fourier Ptychographic Microscopy and Traditional Histopathological Light Microscopy in Renal Membranous Nephropathy

BackgroundHistology remains a cornerstone in the diagnosis and prognosis of renal diseases, with histopathological analysis of kidney tissue being crucial for understanding renal pathophysiology. The availability of multiple stained sections is essential for conducting a comprehensive histopathological analysis and achieving an accurate diagnosis. Recently, Fourier Ptychographic Microscopy (FPM) earned a spot among the most promising microscopy techniques. The ability to provide high-resolution, quantitative phase-contrast images over a wide area, particularly in a stain-free mode, makes FPM highly appealing to experts in histopathology. Since renal pathologies are characterized by subtle morphological changes encoded in tissue slides, phase maps obtained using FPM are well-suited for providing detailed, high-contrast images of tissue structures. Thus, FPM provides a quantitative imaging tool that can be descriptive of the sample and/or expressive of the disease. MethodsIn this study, we explore FPM capability to image pathological kidney tissue, enabling pathologists to select regions of interest within the intricate architecture of renal tissue and zoom in to observe minute submicron structures, ranging from overall tissue organization and glomeruli distribution to individual cell membranes. Attention is focused on membranous glomerulonephritis since it is a nephropathy highly dependent on histological examination. ResultsThe comparative analysis between FPM and traditional light microscopy showed a difference in thickness of glomerular basal membranes between healthy kidney tissues and those affected by membranous glomerulonephritis (MG). Moreover, the results reported in our investigation revealed better glomerular membranes contrast in FPM images with respect to the H&E-stained images. ConclusionsOur study shows the broad potential of FPM in characterizing hallmarks of MG disease even in stain-free tissue slides.

pathology↗

bioRxiv2024

Structural studies of KCTD1 and its disease-causing mutant P20S provide insights into the protein function and misfunction

Members of the KCTD protein family play key roles in fundamental physio-pathological processes. A plethora of literature studies have demonstrated their involvement in cancer, neurodevelopmental disorders, and genetic diseases. Despite two decades of intense investigations, the definition of structure-(mis)function relationships for these proteins is still rather limited. Here, we derived atomic-level structural data on KCTD1, by determining the crystal structure of its P20S mutant, which causes the scalp-ear-nipple syndrome, and performing molecular dynamics simulations. In addition to the expected folded domains (BTB and CTD) the crystal structure unravels that also the N-terminal region that precedes the BTB domain (preBTB) adopts a folded polyproline II (PPII) state. The global structure of the KCTD1 pentamer is characterized by an intricate architecture in which the different subunits mutually exchange domains to generate a closed domain swapping motif. In this framework, the BTB domain of each chain makes peculiar contact with the preBTB and the CTD regions of an adjacent chain. Indeed, the BTB-preBTB interaction is made of a PPII-PPII recognition motif whereas the BTB-CTD contacts are mediated by an unusual (+/-) helix discontinuous association. The inspection of the protein structure, along with the data that emerged from the MD data, provides a clear explanation of the pathogenicity of the SENS mutation P20S and unravels the role of the BTB-preBTB interaction in the insurgence of the disease. Finally, the presence of potassium bound to the central cavity of the CTD pentameric assembly provides insights into the role of the protein in metal homeostasis.

biochemistry↗