Biology subjects

Fujita, B.

Publications and source records attributed to Fujita, B..

3 recordsLinked to original sources

bioRxiv2025

Genetically encoded mechano-sensors with versatile readouts and compact size

Mechanical forces are critical for virtually all fundamental biological processes, yet quantification of mechanical forces at the molecular scale in vivo remains challenging. Here, we present a new strategy using calibrated coiled coils as genetically encoded, compact, tunable, and modular mechano-sensors to substantially simplify force measurement in vivo, via diverse readouts (luminescence, fluorescence and analytical biochemistry) and instrumentation readily available in biology labs. We demonstrate the broad applicability and ease-of-use of these coiled coil mechano-sensors by measuring forces during cytokinesis (formin Cdc12) and endocytosis (epsin Ent1) in yeast, force distributions in nematode axons ({beta}-spectrin UNC-70), and forces transmitted to the nucleus (mini-nesprin-2G) and within focal adhesions (vinculin) in mammalian cells. We report discoveries in intracellular force transmission that have been elusive to existing tools.

cell biology↗

bioRxiv2023

A mechanical circuit in End4p coordinates force transmission during clathrin-mediated endocytosis

Mechanical forces are transmitted from the actin cytoskeleton to the membrane during clathrin-mediated endocytosis (CME) in the fission yeast Schizosaccharomyces pombe. The onset and termination of force transmission is tightly regulated temporally during different stages of CME, and spatially over the surface of the invaginated membrane. How force transmission is regulated and coordinated at the molecular scale is unclear. An adaptor protein in CME, End4p, directly transmits force by binding to both the membrane (through ANTH domain) and F-actin (through THATCH domain). We show that 8pN is required for stable binding between THATCH and F-actin. We also report the discovery and characterization of a new domain on End4p, which we named Rend (R domain in End4p), that resembles R12 of talin. Membrane localization of Rend primes the binding of THATCH to F-actin, and force-induced unfolding of Rend at 15pN terminates the transmission of force during CME. We show that the mechanical properties (mechanical stability, unfolding length, hysteresis) of Rend and THATCH are tuned to form an auto-regulated circuit for the initiation, transmission and termination of force between the actin cytoskeleton and membrane. Shorting the circuit leads to permanent End4p association with the membrane or with F-actin, or failure to enter the force transmission cycle. Mathematical modeling of force transmission through Rend-THATCH connection shows that input force from F-actin is buffered to a narrow range towards the membrane. The mechanical circuit by Rend and THATCH may be conserved and coopted evolutionarily in cell adhesion complexes.

cell biology↗

bioRxiv2019

Identification of a human adult cardiac stem cell population with neural crest origin

Cardiovascular diseases are the major cause of death worldwide, emphasizing the necessity to better understand adult human cardiac cell biology and development. Although the adult heart was considered as a terminally differentiated organ, rare populations of cardiac stem cells (CSCs) have been described so far, with their developmental origin and endogenous function still being a matter of debate.\n\nHere, we identified a Nestin+/S100+/CD105+/Sca1+/cKit- population of CSCs in the myocardium of the adult human heart auricle. Isolated cells showed expression of characteristic neural crest-derived stem cell (NCSC) markers and kept their genetic stability during cultivation in vitro. Cultivated hCSCs efficiently gave rise to functional, beating cardiomyocytes, osteoblasts, adipocytes and neurons. Global transcriptome analysis via RNAseq showed a high similarity between the expression profiles of Nestin+/S100+/CD105+/Sca1+/cKit- hCSCs and adult human NCSCs from the nasal cavity (inferior turbinate stem cells, ITSCs). In detail, 88.1 % of all genes were significantly expressed in both stem cell populations particularly including common NCSC-markers. Based on these observations, we suggest a similar developmental origin of both stem cell populations.\n\nIn summary, we identified a human adult cardiac stem cell population with neural crest-origin, which may also contribute to endogenous cardiac tissue homeostasis and tissue repair in vivo.

cell biology↗