bims-mitpro 2026-02-01 papers

Issue of 2026–02–01
three papers selected by
Andreas Kohler, Umeå University

Mol Cell. 2026 Jan 28. pii: S1097-2765(26)00021-3. [Epub ahead of print]

Mito-nuclear communication: From cellular responses to organismal health.

The co-evolution of mitochondria and the nucleus established constant mito-nuclear communication that is essential for both cellular and organismal homeostasis. At the cell-autonomous level, mitochondrial perturbations activate retrograde pathways such as the mitochondrial unfolded protein response (UPRmt) and the mitochondrial integrated stress response (ISRmt), which couple organelle dysfunction to nuclear transcriptional programs, thereby promoting mitochondrial function and preserving cellular integrity. Importantly, this communication is not confined to individual cells but extends across tissues to coordinate systemic adaptations. Stress signals can be sensed, broadcasted through secreted mitokines and neural circuits, and then interpreted by distal organs to coordinate systemic adaptations. These systemic responses integrate metabolism, immunity, and behavior, conferring resilience to stress and shaping the trajectory of aging. Understanding this multi-layered communication, from the organelle to the organism and its microbial ecosystem, promises new therapeutic strategies to enhance mitochondrial function, promote resilience, and extend healthspan.

Keywords: ISRmt; UPRmt; aging; mito-nuclear communication; mitokine; proteostasis

DOI: https://doi.org/10.1016/j.molcel.2026.01.001

Nat Commun. 2026 Jan 29.

ALKB-1-dependent tRNA methylation is required for efficient paternal mitochondrial elimination.

Zhenhuan Luo, Yimin Li, Chenyang He, Dan Wu, Wenyu Dai, Liubing Hu, Jing Yang, Brian L Harry, Zhenyu Ju, Nektarios Tavernarakis, Hao Wang, Qin-Li Wan, Qinghua Zhou.

Maternal mitochondrial inheritance is secured by mechanisms that exclude paternal mitochondrial DNA (mtDNA). While, epigenetic modifications are vital for spermatogenesis and embryo development, their roles in the paternal mitochondrial elimination (PME) remain poorly understood. Here, we identify ALKB-1, a DNA/RNA demethylase, as a pivotal factor for efficient PME in Caenorhabditis elegans (C. elegans), acting through ALKB-1-dependent modulation of tRNA m1A methylation. Mechanistically, ALKB-1 inactivation leads to m1A hypermethylation of tRNA, which subsequently disrupts protein translation, impairs mitochondrial proteostasis, and increases ROS levels. This cascade activates the oxidative stress response factor SKN-1/Nrf2 and initiates the mitochondrial unfolded protein response (UPRmt) through ATFS-1, causing accumulation of mitochondria and mtDNA in sperm, which ultimately impedes efficient paternal mitochondrial removal and negatively impacts male fertility and embryonic development. Our findings describe a mechanism whereby ALKB-1-mediated tRNA m1A epitranscriptomic modifications are necessary for maintaining mitochondrial quality control, thereby influencing PME efficiency, underscoring the importance of this epitranscriptomic stress checkpoint in upholding proper mitochondrial inheritance during reproduction.

DOI: https://doi.org/10.1038/s41467-026-68813-6

Nat Commun. 2026 Jan 27. 17(1): 1064

Cryo-EM structures of human ClpXP reveal mechanisms of assembly and proteolytic activation.

Wenqian Chen, Gabriel C Lander, Jie Yang.

The human ClpXP complex (hClpXP) orchestrates mitochondrial protein quality control through targeted degradation of misfolded and unnecessary proteins. While bacterial ClpXP systems are well characterized, the assembly and regulation of human ClpXP remain poorly understood. In this study, we elucidate the complete assembly pathway of hClpXP through high-resolution cryo-electron microscopy (cryo-EM) structures. Our findings confirm that hClpP exists as a single-ring heptamer in isolation and reveal a previously undocumented initial assembly complex in which hexameric hClpX first engages with heptameric hClpP. We further demonstrate how this interaction drives substantial conformational rearrangements that facilitate the formation of tetradecameric hClpP within the fully assembled complex. Notably, we characterize a unique eukaryotic sequence in hClpX, termed the E-loop, which plays a critical role in stabilizing hexamer assembly and maintaining ATPase activity. Additionally, we show that peptide binding at the hClpP active site triggers further structural changes essential for achieving full proteolytic competence. Together, these structures provide unprecedented mechanistic insights into the stepwise assembly and activation of hClpXP, significantly advancing our understanding of this essential mitochondrial protein degradation machinery.

DOI: https://doi.org/10.1038/s41467-025-67010-1