bims-raghud 2026-01-25 papers

Issue of 2026–01–25
three papers selected by
Irene Sambri, TIGEM

Cell Commun Signal. 2026 Jan 20.

Peripheral lysosome levels dictate mTORC1 inactivation even when catabolically impaired.

Huy Quang Dang, Therése Forssén, Spyridon Pantelios, Aisegkioul Nteli Chatzioglou, Ewa Kurzejamska, C Theresa Vincent, Yasir Ibrahim, Anders P Mutvei.

The mechanistic target of rapamycin complex 1 (mTORC1) is a central driver of cell growth that is frequently hyperactivated in cancer. While mTORC1 is activated at the lysosomal surface in response to growth factors and amino acids, the processes governing its inactivation are not fully understood. Here, we report that sustained mTORC1 suppression during leucine or arginine starvation requires the translocation of peripheral lysosomes to the perinuclear region. Our data suggest that a pool of mTOR remains active at peripheral lysosomes during starvation, and that increased spatial separation between lysosomes and the plasma membrane attenuates PI3K/Akt signaling-thereby reducing inputs that otherwise maintain mTORC1 activity. Consequently, preventing lysosome translocation and increasing peripheral lysosome levels sustains mTORC1 signaling during prolonged starvation in a PI3K/Akt-dependent manner independently of autophagy. Under these conditions, mTORC1 signaling persists even when lysosomal catabolism is perturbed by chloroquine or concanamycin A. Collectively, these data indicate that the peripheral lysosome pool, even when catabolically impaired, can sustain mTORC1 signaling under nutrient scarcity, by modulating PI3K/Akt signaling input to the pathway. These observations identify peripheral lysosome levels as a critical determinant of mTORC1 inactivation during nutrient stress and may have implications for diseases with aberrant mTORC1 signaling, including cancer.

Keywords: Amino acid deprivation; Catabolically impaired lysosomes; Lysosome positioning; MTORC1; PI3K-Akt signaling; Rab7; Rap1

DOI: https://doi.org/10.1186/s12964-026-02659-9

EMBO Rep. 2026 Jan 20.

Hyperactivation of mTORC1 blocks stem cell fate transitions through TFE3-NuRD association.

Peizhi Li, Shuhui Xu, Xinyu Wu, Yin Gao, Tanveer Ahmed, Yinghua Huang, Dajiang Qin, Baoming Qin, Lulu Wang, Xueting Xu.

Mechanistic target of rapamycin complex 1 (mTORC1) integrates signals from nutrients, growth factors, and cellular stress to regulate biosynthesis and maintain homeostasis. Dysregulated mTORC1 disrupts stem cell homeostasis and impairs cell fate transitions in vivo and in vitro. Previous studies have shown that mTORC1 hyperactivation promotes nuclear translocation of TFE3, blocking pluripotency exit in both mouse and human naïve embryonic stem cells. Similarly, our earlier work has demonstrated that sustained mTORC1 activation impedes somatic cell reprogramming via the transcriptional coactivator PGC1α. This raises the question of how mTORC1 coordinates gene transcription across distinct transitions in pluripotent cells. Here, we show that TFE3 mediates the transcriptional blockade induced by mTORC1 hyperactivation during reprogramming. Notably, during both pluripotency exit and reprogramming, TFE3 recruits the NuRD corepressor complex to repress genes essential for cell fate transitions. These findings uncover a shared mechanism by which mTORC1 and TFE3 regulate stem cell identity, highlighting the dual regulatory role of TFE3 and its potential implications in development, aging, and tumorigenesis.

Keywords: NuRD Complex; Pluripotency Exit; Somatic Cell Reprogramming; TFE3; mTORC1

DOI: https://doi.org/10.1038/s44319-025-00544-z

Front Bioeng Biotechnol. 2025 ;13 1719533

Mini-hearts for disease modeling and drug testing - process optimization versus biological functionality.

Jana Hecking, Mariel Cano-Jorge, Robert Passier, José Manuel Rivera-Arbeláez.

Traditional two-dimensional cell cultures and in vivo animal studies fail to fully recapitulate human cardiac physiology, highlighting the urgent need for more relevant human-based models. Engineered three-dimensional cardiac systems - including organoids, engineered heart tissues, and heart-on-chip platforms offer promising alternatives, providing structural and functional insights into cardiac biology. However, a critical limitation of these models is their inability to perform fluid pumping and relaxation, which together define fundamental heart function. Engineered cardiac chambers have emerged to address this gap, enabling physiologically relevant pressure-volume measurements and capturing both contractile and diastolic dynamics that mimic aspects of native cardiac hemodynamics. This mini-review examines the current state of engineered cardiac chambers and highlights their main design features. We discuss their applications in disease modeling and drug testing, and outline key factors influencing the optimization of these models, including balancing biological fidelity with process efficiency through modular design principles. Overall, engineered cardiac chambers represent a unique, powerful platform to improve mechanistic understanding of cardiac disease, offering significant potential to advance cardiovascular research and therapeutic development.

Keywords: 3D cardiac models; disease modeling; drug testing; engineered cardiac chambers; tissue engineering

DOI: https://doi.org/10.3389/fbioe.2025.1719533