PubMed · 11613776
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H Buntz. 1985. [Not Available].. https://pubmed.ncbi.nlm.nih.gov/11613776/
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The stria vascularis (SV) is an essential component of the inner ear that regulates the ionic environment required for hearing. SV degeneration disrupts cochlear homeostasis, leading to irreversible hearing loss, yet a comprehensive understanding of the SV, and consequently therapeutic availability for SV degeneration, is lacking. We developed a whole-tissue explant model from neonatal and mature mice to create a platform for advancing SV research. We validated our model by demonstrating that the proliferative behavior of the SV in vitro mimics SV in vivo. We also provided evidence for pharmacological experimentation by investigating the role of Wnt/β-catenin signaling in SV proliferation. Finally, we performed single-cell RNA sequencing from in vivo neonatal and mature mouse SV and surrounding tissue and revealed key genes and pathways that may play a role in SV proliferation and maintenance. Together, our results contribute new insights into investigating biological solutions for SV-associated hearing loss.
Structural factors to regulate the heme reorientation reaction in myoglobin were examined and we found that the side chain at position 107 (Ile107), which is located between the 2-vinyl and 3-methyl groups of heme, forms a kinetic barrier for the heme rotation about the alpha-gamma axis. The phenylalanine-substituted mutant showed an extremely slow heme reorientation rate, compared to that of the wild-type protein, while replacement by the decreased side chain, valine, at position 107 accelerated the reorientation reaction. Considering that the spectroscopic data show only minor structural changes in the heme environments of the Ile107 mutants, the side chain at position 107 sterically interacts with the heme peripheral groups in the activation state for the heme reorientation, which supports the intramolecular mechanism that the heme rotates about the alpha-gamma axis without leaving the "protein cage."
Numerous features distinguish prokaryotes from eukaryotes, chief among which are the distinctive internal membrane systems of eukaryotic cells. These membrane systems form elaborate compartments and vesicular trafficking pathways, and sequester the chromatin within the nuclear envelope. The nuclear pore complex is the portal that specifically mediates macromolecular trafficking across the nuclear envelope. Although it is generally understood that these internal membrane systems evolved from specialized invaginations of the prokaryotic plasma membrane, it is not clear how the nuclear pore complex could have evolved from organisms with no analogous transport system. Here we use computational and biochemical methods to perform a structural analysis of the seven proteins comprising the yNup84/vNup107-160 subcomplex, a core building block of the nuclear pore complex. Our analysis indicates that all seven proteins contain either a beta-propeller fold, an alpha-solenoid fold, or a distinctive arrangement of both, revealing close similarities between the structures comprising the yNup84/vNup107-160 subcomplex and those comprising the major types of vesicle coating complexes that maintain vesicular trafficking pathways. These similarities suggest a common evolutionary origin for nuclear pore complexes and coated vesicles in an early membrane-curving module that led to the formation of the internal membrane systems in modern eukaryotes.