Biology subjects

Allen, W.

Publications and source records attributed to Allen, W..

4 recordsLinked to original sources

bioRxiv2026

The centromere localization domain of kinetoplastid kinetochore protein KKT2 recognizes the free N-terminus of histone H3

Kinetochores are multiprotein complexes that drive chromosome segregation in eukaryotes. Kinetoplastids, a group of early-diverging eukaryotes that lack canonical kinetochore components, have a unique set of kinetochore proteins. How their kinetochores are assembled specifically at centromeres in the absence of a centromere-specific histone H3 variant CENP-A remains unknown. Here, we demonstrate that the centromere localization (CL) domain of KKT2 has similarities to a ZZ domain. An invariant aspartate present in histone H3-binding ZZ domains is conserved in the KKT2 CL domain. Using nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry (ITC), we show that Trypanosoma brucei KKT2 CL binds the N-terminus of histone H3. Strikingly, even mono-methylation of the N-terminal amino group of histone H3 abolishes the binding. Our study raises a possibility that centromere-specific kinetochore assembly in T. brucei is ensured by abundant N-terminal methylations of histone H3 in non-centromeric regions.

cell biology↗

bioRxiv2025

Comparative Analysis of Primary and Liver Fibroblasts Reveals MET as a Potent Target in Pancreatic Cancer Metastasis

The tumor microenvironment drives many malignant features of pancreatic ductal adenocarcinoma (PDAC). The fibroblasts within pancreatic tumors promote tissue remodeling, immune suppression, and resistance to therapy. However, the interactions between stromal populations and pancreatic cancer cells are less understood in the liver, the most frequent site of PDAC metastasis. To address this, we employ single cell transcriptomics to compare primary pancreatic vs. liver PDAC lesions. Here, we identify the expression of hepatocyte growth factor (HGF) in fibroblasts and its receptor MET in cancer cells are both markedly increased in the PDAC liver niche. Using functional assays, we validate that mitogenic MET signaling is activated in PDAC cells by liver-derived fibroblasts. Importantly, the inhibition of MET signaling leads to reduced tumor growth in immune competent mouse models. Collectively, our data demonstrates that liver stromal-epithelial crosstalk networks engage in signaling pathways distinct from primary pancreatic tumors, highlighting opportunities to develop new treatments for metastatic disease.

cancer biology↗

bioRxiv2022

Divergent polo boxes in KKT2 and KKT3 initiate the kinetochore assembly cascade in Trypanosoma brucei

Chromosome segregation requires assembly of the macromolecular kinetochore complex onto centromeric DNA. While most eukaryotes have canonical kinetochore proteins that are widely conserved among eukaryotes, evolutionarily divergent kinetoplastids have a unique set of kinetochore proteins. Little is known about the mechanism of kinetochore assembly in kinetoplastids. In this study, we have characterized two homologous kinetoplastid kinetochore proteins, KKT2 and KKT3, that constitutively localize at centromeres and promote the recruitment of other kinetochore proteins. KKT2 and KKT3 have three domains that are highly conserved among kinetoplastids: an N-terminal kinase domain of unknown function, the centromere localization domain in the middle, and the C-terminal domain that has weak similarity to polo boxes of Polo-like kinases. We show that the kinase activity of KKT2 is essential for accurate chromosome segregation, while that of KKT3 is dispensable for cell growth in the procyclic form of Trypanosoma brucei. Crystal structures of their divergent polo boxes reveal differences between KKT2 and KKT3. We also show that the divergent polo boxes of KKT3 are sufficient to recruit KKT2 in T. brucei. Furthermore, we identify the C-terminal domain of KKT1 as a direct interaction partner for the divergent polo boxes of KKT2, but not KKT3. KKT6 is found to interact with KKT1. These results show that KKT2 and KKT3 recruit downstream kinetochore proteins by direct protein-protein interactions using their divergent polo boxes.

cell biology↗

bioRxiv2019

Dendritic calcium signals in rhesus macaque motor cortex drive an optical brain-computer interface

Calcium imaging has rapidly developed into a powerful tool for recording from large populations of neurons in vivo. Imaging in rhesus macaque motor cortex can enable the discovery of new principles of motor cortical function and can inform the design of next generation brain-computer interfaces (BCIs). Surface two-photon (2P) imaging, however, cannot presently access somatic calcium signals of neurons from all layers of macaque motor cortex due to photon scattering. Here, we demonstrate an implant and imaging system capable of chronic, motion-stabilized two-photon (2P) imaging of calcium signals from in macaques engaged in a motor task. By imaging apical dendrites, some of which originated from deep layer 5 neurons, as as well as superficial cell bodies, we achieved optical access to large populations of deep and superficial cortical neurons across dorsal premotor (PMd) and gyral primary motor (M1) cortices. Dendritic signals from individual neurons displayed tuning for different directions of arm movement, which was stable across many weeks. Combining several technical advances, we developed an optical BCI (oBCI) driven by these dendritic signals and successfully decoded movement direction online. By fusing 2P functional imaging with CLARITY volumetric imaging, we verify that an imaged dendrite, which contributed to oBCI decoding, originated from a putative Betz cell in motor cortical layer 5. This approach establishes new opportunities for studying motor control and designing BCIs.

neuroscience↗