Sultana, J. | Search bioRxiv

bioRxiv2024

Experimental type 1 diabetes metabolically rejuvenates CD8+ T cells for improved control of tumor growth through an IGF1-IGF1R axis

AbstractEpidemiological studies suggest that patients with pre-existing type 1 diabetes (T1D) have a decreased risk of developing melanoma, prostate cancer, and breast cancer, although the underlying mechanism remains to be elucidated. In translational modelling, we observed that streptozotocin (STZ) induced T1D mice exhibited restricted melanoma and carcinoma (mammary, lung and colon) growth in association with extended overall survival. Tumor-infiltrating CD8+ T cells were found to be responsible for tumor growth restriction. Tumor infiltrating CD8+ T cells but not tumor cells themselves exhibited higher glycolytic and cytotoxic activities in T1D hosts. Such improved anti-tumor T cell function was linked to selective upregulated expression of insulin-like growth factor 1, insulin-like growth factor 1 receptor, and phospho-mTOR in CD8+ T cells in the TME. T1D patient derived CD8+ T cells displayed superior activation in vitro after tumor antigen stimulation vs. non-diabetic CD8+ T cells. Activation of T1D patient derived CD8+ T cells was sensitive to targeted antagonism of IGF1R and mTOR, supporting the operational involvement of the IGF1R-mTOR signaling axis. Our results suggest that selective activation of the intrinsic IGF1R-mTOR signaling axis in CD8+ T cells represents a preferred endpoint to achieving more effective immunotherapy outcomes and improved cancer patient management. SignificanceExperimental type 1 diabetes decelerates tumor growth through metabolic activation of cytotoxic T cells dependent on an IGF1R-mTOR signaling pathway. CD8+IGF1R+IGF1+ T cells play a crucial role in T1D dependent tumor control.

cancer biology↗

bioRxiv2023

Dysregulated actin dynamics and cofilin correlate with TDP-43 pathology in sporadic amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal, rapidly progressive neurodegenerative disorder affecting motor neurons, that overlaps significantly with frontotemporal dementia (FTD). Most cases are sporadic (90%) with undefined aetiology, but pathological forms of TAR-binding protein 43 (TDP-43), involving its misfolding, aggregation and mislocalisation from the nucleus to the cytoplasm, are present in motor neurons in almost all cases (97%) and [~]45% FTD cases. Actin is the most abundant protein in eukaryotic cells, with structural roles in the cytoskeleton and diverse signalling functions. This includes neuronal-specific roles in dendritic spines, synapses, axonal growth cones, and plasticity. Actin is in constant dynamic equilibrium between two forms: free monomeric, globular actin (G-actin) and polymeric, filamentous actin (F-actin). Actin dynamics is regulated by several key actin-binding proteins, including tropomyosin 4.2 (Tpm4.2) and cofilin, which depolymerises actin filaments. Cofilin is activated by phosphorylation at Ser3 via LIM domain kinase1/2 (LIMK1/2), which is also regulated by phosphorylation via Rac1/cdc42. Here we demonstrate that actin dynamics is closely associated with pathological TDP-43 in ALS. More F-actin relative to G-actin was detected in lumbar spinal cords from both sporadic ALS patients and a mouse model displaying TDP-43 pathology (rNLS), and in neuronal cells expressing cytoplasmic TDP-43. Hence actin dynamics is dysregulated in sporadic ALS, resulting in more actin polymerization. We also detected increased levels of Tpm 4.2, Rac1/cdc42, and increased phosphorylation of both LIMK1/2 and cofilin, in sporadic ALS patients. TDP-43 also physically interacted with actin in vitro and in cell lysates, providing additional insights into actin dysregulation in ALS. rNLS mice display motor neuron loss and key ALS/MND behavioural phenotypes, and increased cofilin phosphorylation was also detected in these animals at symptom onset, implying that actin dynamics actively contributes to neurodegeneration. Moreover, pharmacological induction of actin polymerization produced features typical of pathological TDP-43 (cytoplasmic mis-localisation and formation of inclusions and stress granules) implying that actin dysregulation contributes to TDP-43 pathology in ALS. Importantly, we also detected more cofilin phosphorylation in spinal motor neurons from sporadic patients compared to healthy controls, revealing that our observations are clinically relevant and present in the relevant cell type. This study therefore identifies dysregulated actin dynamics as a novel disease mechanism associated with TDP-43 pathology and hence most ALS cases. It also implies that regulating cofilin or LIMK1/2 phosphorylation may be a novel therapeutic strategy in ALS, FTD and other diseases involving TDP-43 pathology.

neuroscience↗