Biology subjects

Taga, Y.

Publications and source records attributed to Taga, Y..

4 recordsLinked to original sources

bioRxiv2026

Platinum Cross-linked Collagen Matrices with Tunable Stiffness as a Platform to Investigate Cellular Mechanosensing

The mechanical properties of the cellular microenvironment are key regulators of cellular physiology. Although the field of cancer mechanobiology has attracted attention, the availability of matrix systems with independently and precisely tunable mechanical properties remains limited. Our group previously developed a collagen gel with enhanced mechanical strength by cross-linking collagen molecules using a platinum complex. In this study, we investigated the tunability of the mechanical properties of the platinum cross-linked collagen gel (PCG) and demonstrated that mechanical parameters can be controlled by varying the amount of the platinum complex. In addition, we examined how matrix mechanical properties modulate the phenotypes of lung adenocarcinoma A549 cells using the collagen matrix. Although A549 cells exhibited significant morphological alterations on stiffer matrices, these changes were not accompanied by classical epithelial-to-mesenchymal transition (EMT). Instead, they were associated with the upregulation of diverse gene expression related to cancer malignancy. We focused on maternal embryonic leucine zipper kinase (MELK) whose gene expression increased on stiffer matrices. Consistently, A549 cells cultured on stiffer matrices displayed enhanced sensitivity to a MELK-targeting anticancer drug. These findings highlight the potential of the matrices with tunable mechanical parameters not only to provide variety of physiological microenvironment but also to advance anticancer drug screening when combined with gene expression analysis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/720034v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@419074org.highwire.dtl.DTLVardef@72ef67org.highwire.dtl.DTLVardef@1c36e17org.highwire.dtl.DTLVardef@170dc33_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIPlatinum cross-linked collagen gel enables independent tuning of compressive and shear elasticities. C_LIO_LICellular functions may be regulated by matrix mechanical parameters through distinct mechanisms. C_LIO_LICorrelation analysis between matrix mechanical parameters and cancer cell gene expression provides a rational strategy for therapeutic drug screening. C_LI

bioengineering↗

bioRxiv2025

A facile method for fluorescent visualization of newly synthesized fibrous collagen by capturing the allysine aldehyde groups serving as cross-link precursors

The fibrous structures of collagen provide physical strength and stability to tissues and organs. Abnormalities in their orientation, growth, and remodeling cause morphogenetic defects and diseases including fibrosis, highlighting the importance of understanding how collagen fibers are organized within tissues. However, this process remains difficult to study, as methods for fluorescently labeling collagen fibers with simple protocols and visualizing their three-dimensional structure are still limited. Here we describe a convenient method for fluorescent labeling of collagen fibers in vertebrate tissues. Using DAF-FM, a probe originally developed for nitric oxide detection, premature collagen fibers can be visualized through covalent binding to allysine residues, which serve as precursors of collagen cross-linking. We further show that combining two probes with different emission spectra, DAF-FM and DAR-4M, enables pulse-chase labeling of newly synthesized collagen fibers. This approach provides a practical tool for investigating collagen dynamics during tissue development and remodeling.

developmental biology↗

bioRxiv2021

Preservation of collagen in the soft tissues of frozen mammoths

We investigated the characteristics of extracellular matrix (ECM) in the soft tissue of two frozen baby woolly mammoths (Mammuthus primigenius) that died and were buried in Siberian permafrost approximately 40,000 years ago. Morphological and biochemical analyses of mammoth lung and liver demonstrated that those soft tissues were preserved at the gross anatomical and histological levels. The ultrastructure of ECM components, namely a fibrillar structure with a collagen-characteristic pattern of cross-striation, was clearly visible with transmission and scanning electron microscopy. Type I and type IV collagens were detected by immunohistochemical observation. Quantitative amino acid analysis of liver and lung tissues of the baby mammoths indicated that collagenous protein is selectively preserved in these tissues as a main protein. Type I and type III collagens were detected as major components by means of liquid chromatography-mass spectrometry analysis after digestion with trypsin. These results indicate that the triple helical collagen molecule, which is resistant to proteinase digestion, has been preserved in the soft tissues of these frozen mammoths for 40,000 years.

paleontology↗

bioRxiv2019

Re-evaluation of lysyl hydroxylation in the collagen triple helix: lysyl hydroxylase 1 and prolyl 3-hydroxylase 3 have site-differential and collagen type-dependent roles in lysine hydroxylation.

Collagen is the most abundant protein in humans and is heavily post-translationally modified. Its biosynthesis is very complex and requires three different types of hydroxylation (two for proline and one for lysine) that are generated in the rough endoplasmic reticulum (rER). These processes involve many enzymes and chaperones which were collectively termed the molecular ensemble for collagen biosynthesis. However, the function of some of the proteins in this molecular ensemble is controversial. While prolyl 3-hydroxylase 1 and 2 (P3H1, P3H2) are bona fide collagen prolyl 3-hydroxylases, the function of prolyl 3-hydroxylase 3 (P3H3) is less clear. A recent study of P3H3 null mice demonstrated that this enzyme had no activity as prolyl 3-hydroxylase but may instead act as a chaperone for lysyl hydroxylase 1 (LH1). LH1 is required to generate hydroxylysine for crosslinking within collagen triple helical sequences. If P3H3 is a LH1 chaperone that is critical for LH1 activity, P3H3 and LH1 null mice should have similar deficiency in lysyl hydroxylation. To test this hypothesis, we compared lysyl hydroxylation in type I and V collagen from P3H3 and LH1 null mice. Our results indicate LH1 plays a global role for lysyl hydroxylation in triple helical domain of type I collagen while P3H3 is indeed involved in lysyl hydroxylation particularly at crosslink formation sites but is not required for all lysyl hydroxylation sites in type I collagen triple helix. Furthermore, although type V collagen from LH1 null mice surprisingly contained as much hydroxylysine as type V collagen from wild type, the amount of hydroxylysine in type V collagen was clearly suppressed in P3H3 null mice. In summary, our study suggests that P3H3 and LH1 likely have two distinct mechanisms to distinguish crosslink formation sites from other sites in type I collagen and to recognize different collagen types in the rER. Author summaryCollagen is one of the most heavily post-translationally modified proteins in the human body and its post-translational modifications provide biological functions to collagen molecules. In collagen post-translational modifications, crosslink formation on a collagen triple helix adds important biomechanical properties to the collagen fibrils and is mediated by hydroxylation of very specific lysine residues. LH1 and P3H3 show the similar role in lysine hydroxylation for specific residues at crosslink formation sites of type I collagen. Conversely, they have very distinct rules in lysine hydroxylation at other residues in type I collagen triple helix. Furthermore, they demonstrate preferential recognition and modification of different collagen types. Our findings provide a better understanding of the individual functions of LH1 and P3H3 in the rER and also offer new directions for the mechanism of lysyl hydroxylation followed by crosslink formation in different tissues and collagens.

biochemistry↗