Coordinates: 39°2′11.67″N 94°34′27.08″W / 39.0365750°N 94.5741889°W / 39.0365750; -94.5741889The Stowers Institute for Medical Research is a biomedical research organization that conducts basic research on genes and proteins that control fundamental processes in living cells to analyze diseases and find keys to their causes, treatment, and prevention. It is located in Kansas City, Missouri adjacent to the University of Missouri–Kansas City main campus.The Institute has spent over 1 billion $US on research.
Telomerase biogenesis is a multistep process requiring the coordinated action of several accessory factors. In the fission yeast Schizosaccharomyces pombe, the telomerase RNA TER1 undergoes spliceosome-mediated 3'-end processing, followed by association with the Pof8/Bmc1/Thc1 complex, which facilitates binding of the Lsm2-8 complex. Lsm2-8 protects TER1 from nucleolytic degradation and promotes recruitment of the catalytic subunit Trt1. Here, we identify Pop6, Pop7, and Pop100, three subunits of the RNase P/MRP complex, as components of the active telomerase holoenzyme. These proteins associate with a stem-loop-stem structure near the TER1 pseudoknot that resembles the P3 domain found in RNase P/MRP RNAs. A single-nucleotide change within this P3-like loop disrupts Pop protein binding, resulting in reduced telomerase activity and severe telomere shortening. This mutation also impairs the assembly of key telomerase subunits and alters the folding of the template-pseudoknot region of TER1. Our findings reveal a critical role for Pop6, Pop7, and Pop100 in chaperoning TER1 into a conformation that promotes functional telomerase assembly and underscore the remarkable evolutionary plasticity of telomerase biogenesis.
Intrinsically disordered regions (IDRs) and intrinsically disordered proteins (IDPs) play pivotal roles in cellular signaling, molecular recognition, and the regulation of various biological processes. These flexible and conformationally dynamic protein segments are difficult to study using structural analysis methods and computational approaches including AlphaFold. Therefore a critical challenge arises when attempting to understand the structural basis of protein-protein interactions involving IDRs. Here we demonstrate that the poorly characterized C16orf87 protein, which we rename as MHAP1, forms a stable complex with HDAC2 and MIER1. These three proteins all contain IDRs whose structure is unknown. We implemented an integrative approach combining experimental crosslinking data with computational modeling techniques (I-TASSER, HADDOCK, AlphaFold) to probe the IDR-driven assembly of the HDAC1:MIER2:MHAP1 complex and build an integrative structural model of this complex. The C-terminal domain of HDAC2, a poorly characterized IDR, promotes interactions between the ELM2 domain of MIER1 as well as the N- and C-termini of MHAP1. These results contrast with most current literature, including the results from AlphaFold alone that are missing structural information on HDAC C-domain. The approach herein can be generalized to study other complexes, emphasizing the need for integrative approaches in determining the 3D structures of IDR/IDP-driven complexes.
Planarian flatworms are known for their remarkable regenerative capacity; however, the precise intercellular communication mechanisms underlying this process remain unsolved. Here, we report the discovery and characterization of abundant extracellular vesicles (EVs) in planarians. Using imaging and molecular analysis, we show conservation of biogenesis, morphology, and protein composition of planarian EVs. Environmental stressors significantly elevate EV release, indicating that planarians dynamically regulate vesicle production. Functionally, planarian EVs mediate intercellular communication by transferring regulatory signals: We find that they shuttle small RNAs that effect systemic RNA interference (RNAi) throughout the organism. Notably, gene knockdown experiments reveal a crucial role for AGO-3, a member of the Argonaute family of proteins, in modulating the association of small interfering RNAs with EVs, linking the intracellular RNAi machinery to EV-based signaling. These findings highlight EVs as pivotal mediators of cell-cell communication in planarians, with broad implications for understanding the coordination of gene regulation and tissue regeneration in animals.
Age-dependent reproductive decline has become a significant global health concern as the average maternal age at first birth increases. Fertility loss associated with reproductive aging is driven in part by alterations to ovarian composition and function, dysregulation of folliculogenesis, and increased inflammatory signaling. Our understanding of the molecular changes underlying ovarian aging has been expanded by single-cell and spatial transcriptomic studies, which identified infiltration of immune cells as a feature of ovarian aging. However, the function of these age-associated immune cells and their potential contributions to the inflammaging phenotype remain unclear. In this study, we integrate single-cell and spatial transcriptomics to define changes in the composition and intercellular signaling in the aging mouse ovary. We identify specific macrophage and T cell subpopulations that increase with age and are key sources of pro-inflammatory signaling in old ovaries. Further, we predict bidirectional signaling between these pro-inflammatory cells and granulosa cell populations that may impair follicular growth and development while promoting immune cell recruitment. These findings provide insights into the mechanisms that drive ovarian inflammaging.
Memory requires experience-dependent alterations in the synaptic proteome. Chaperones interface between the environment and the proteome. Manipulating J-domain protein (JDP) chaperones, the most diverse family of chaperones, in a Drosophila neuronal circuit that encodes associative long-term memories, we identified yet uncharacterized JDPs that transduce sensory cues. One of these JDPs, CG10375, which we named Funes, enhances memory when overexpressed and impairs memory when functionally impaired. Funes overexpression enhances memory formation even when sensory stimuli are suboptimal. At the circuit level, Funes acts on neurons where conditioned and unconditioned stimuli converge to form associative memories. From a proteomic-based screen, we found that overexpression of Funes changes the solubility of a small subset of proteins, one of which is the mRNA-binding protein Orb2. Combining in vitro and in vivo biophysical, biochemical, and cryo-EM structural analyses, we found that Funes associates with oligomeric Orb2 and promotes the formation of translationally active amyloids. Perturbation of the conserved J domain eliminates the ability of Funes to facilitate amyloid assembly and promote memory. We posit that the brain harbors chaperones that influence memory by regulating physiological amyloid formation.
