Biology subjects

Mitchel, A.

Publications and source records attributed to Mitchel, A..

3 recordsLinked to original sources

bioRxiv2025

RAB1A is a novel vulnerability in uveal melanoma revealed by dual inhibition of MNK1/2 and mTOR.

Uveal melanoma (UM) is an eye cancer that is fatal upon metastasis to the liver. Most treatments trialed in UM fail to provide therapeutic benefit, thus there is an urgent need for novel treatment strategies. The MAPK and PI3K signaling pathways, key molecular drivers found to be hyper-activated in UM, converge on the MNK1/2-eIF4E and mTORC1/2-4EBP axes. Here, we demonstrate that the pharmacologic inhibition of MNK1/2 in combination with an mTOR inhibitor impairs clonogenic outgrowth and UM cell invasion. Using proteomic analyses, we reveal that combined MNK1/2 and mTOR inhibition disrupts Golgi homeostasis and protein vesicle trafficking mainly due to downregulated RAB1A expression, a master regulator of intracellular protein transport. We uncover that the knockdown of RAB1A blocks liver metastasis, a result that is recapitulated by combined pharmacologic inhibition of MNK1/2 and mTOR. Finally, we show that RAB1A expression reshapes the surfaceome by increasing the abundance of plasma membrane proteins associated with poor overall survival in UM, highlighting its potential as a biomarker. This study identifies protein vesicle transport as an unrecognized vulnerability in UM and supports a mechanistic rationale for targeting MNK1/2 and mTOR in metastatic UM.

cancer biology↗

bioRxiv2025

Blood Vessels Bioengineered from Induced Pluripotent Stem Cell Derived Mesenchymal Stem Cells and Functional Scaffolds

The development of small-diameter vascular grafts remains a major challenge in tissue engineering due to limited remodelling and regenerative capabilities. While strides have been made on the biofabrication of vessel mimics, little clinical translation success had been achieved to treat coronary artery disease (CAD). This study aimed to fabricate patient-specific bioengineered vessels using induced pluripotent stem cells (iPSCs) and functionalised biodegradable scaffolds. Human iPSCs were differentiated into mesenchymal stem cells (iMSCs) using SB431542, then further into vascular smooth muscle cells (VSMCs) with PDGF-BB and TGF-{beta}1. Human bone marrow-derived MSCs (hBM-MSCs) were used to optimize differentiation protocols. Electrospun poly-L-lactide (PLLA) scaffolds coated with silk fibroin improved cell adhesion and proliferation. Both hBM-MSCs and iMSCs were seeded on these scaffolds for in-scaffold VSMC differentiation. The resulting cell-laden scaffolds were rolled into tubular structures ([~]3 mm inner diameter, [~]20 mm length). Over 34-36 days, iPSCs differentiated into iMSCs expressing MSC markers (CD73, CD90, CD105), followed by successful VSMC differentiation within 9 days, confirmed by -SMA, CNN1, SM22, and MYH-11 expression. Silk fibroin-coated PLLA scaffolds enhanced MSC adhesion and proliferation compared to uncoated scaffolds. The engineered tubular grafts displayed VSMC markers and mechanical properties akin to autologous coronary artery bypass grafting (CABG) grafts. This study developed a versatile method to fabricate tissue-engineered blood vessels using stem cells and silk fibroin-coated scaffolds. The resulting grafts exhibited tunica media-like structures and mechanical properties comparable to autografts used in CABG, showing strong potential for clinical application.

bioengineering↗

bioRxiv2021

The Cell Adhesion Molecule TMIGD1 Binds to Moesin and Regulates Tubulin Acetylation and Cell Migration

BackgroundThe cell adhesion molecule transmembrane and immunoglobulin (Ig) domain containing1 (TMIGD1) is a novel tumor suppressor that plays important roles in regulating cell-cell adhesion, cell proliferation and cell cycle. However, the mechanisms of TMIGD1 signaling are not yet fully elucidated. ResultsTMIGD1 binds to the ERM family proteins moesin and ezrin, and an evolutionarily conserved RRKK motif on the carboxyl terminus of TMIGD1 mediates the interaction of TMIGD1 with the N-terminal ERM domains of moesin and ezrin. TMIGD1 governs the apical localization of moesin and ezrin, as the loss of TMIGD1 in mice altered apical localization of moesin and ezrin in epithelial cells. In cell culture, TMIGD1 inhibited moesin-induced filopodia-like protrusions and cell migration. More importantly, TMIGD1 stimulated the Lysine (K40) acetylation of -tubulin and promoted mitotic spindle organization and CRISPR/Cas9-mediated knockout of moesin impaired the TMIGD1-mediated acetylation of -tubulin and filamentous (F)-actin organization. ConclusionsTMIGD1 binds to moesin and ezrin, and regulates their cellular localization. Moesin plays critical roles in TMIGD1-dependent acetylation of -tubulin, mitotic spindle organization and cell migration. Our findings offer a molecular framework for understanding the complex functional interplay between TMIGD1 and the ERM family proteins in the regulation of cell adhesion and mitotic spindle assembly, and have wide-ranging implications in physiological and pathological processes such as cancer progression.

cell biology↗