Biology subjects

Jacobsen, E.

Publications and source records attributed to Jacobsen, E..

4 recordsLinked to original sources

bioRxiv2025

Long-term temporal stability of circulating proteins in older adults

Circulating proteins reflect diverse biological processes and can offer critical insights into an individual s overall health and aging trajectory. The circulating proteome is shaped by a complex interplay of genetic, biological, and environmental factors across the lifespan. However, little is known about which factors influence its long-term temporal stability. Here we used SomaScan proteomics to evaluate the five-year temporal stability of 7,288 proteins measured in serum from 3,093 participants (mean age 76 years) of the Age, Gene/Environment Susceptibility (AGES)-Reykjavik study. We observed a wide variability in the temporal stability of individual proteins, with temporally stable proteins more often being extracellular and associated with diseases, while temporally variable proteins are typically involved in intracellular housekeeping functions. We demonstrate that temporal stability of circulating proteins does not reflect that of transcriptomic stability in tissues, and that genetic effects and disease stage are two major contributors to protein temporal stability in the circulation. Our findings underscore the protein-specific differences in long-term temporal stability, and the genetic and biological factors influencing them, which are particularly important to consider in the context of biomarker development and precision medicine.

genomics↗

bioRxiv2024

E-cadherin endocytosis promotes non-canonical EGFR:STAT signalling to induce cell death and inhibit heterochromatinisation

Signalling molecules often contribute to several signalling pathways that produce distinct transcriptional outputs and cellular phenotypes. One of the major unanswered questions in cell biology is how multiple activities of signalling molecules are coordinated in space and time in vivo. Here, we focus on the Signal Transducer and Activator of Transcription (STAT) protein as a paradigm of signalling molecules involved in several independent signalling pathways. In addition to the canonical pathways, whereby STAT is phosphorylated and activated by Janus Kinases, STAT is involved in at least two non-canonical pathways. In one pathway, STAT is activated by the Epidermal Growth Factor Receptor (EGFR) promoting apoptosis. In another, it binds the Heterochromatin Protein 1 (HP1) to enhance heterochromatin formation. Using Drosophila wing discs as an epithelial system, we demonstrate that all three STAT activities coexist in this tissue. We provide evidence that while the canonical STAT signalling is dominant over non-canonical pathways, EGFR:STAT and HP1:STAT pathways compete for the availability of unphosphorylated STAT. We also describe the role of the cell-cell adhesion protein E-cadherin in EGFR:STAT signalling. Both EGFR and STAT colocalise with E-cadherin at cell-cell junctions and on intracellular vesicles. Elevated intracellular E-cadherin promotes EGFR:STAT pathway leading to apoptosis, whereas blocking E-cadherin endocytosis prevents apoptosis induction. Altogether, we propose that E-cadherin endocytosis controls the balance between two non-canonical STAT activities in a potential tumour-suppressive mechanism - junctional disassembly in dysregulated epithelial-to-mesenchymal transitions would shift this balance towards the EGFR:STAT signalling to promote apoptosis.

cell biology↗

bioRxiv2024

The transcription factor Chronophage/BCL11A/B promotes intestinal stem cell proliferation and endocrine differentiation in the Drosophila intestine

Tissue-resident Adult Stem Cells (ASCs) need to continuously adapt their rate of division and differentiation based on their tissue environment. However, the gene regulatory networks that govern these decisions in ASCs and how they respond to challenges such as infection are often not fully understood. We identify a novel role for the transcription factor (TF) Chronophage (Cph) in ISC proliferation and entero-endocrine (EE) cell differentiation. Cph is a Z2H2 zinc TF orthologous to mammalian BCL11A/B that are involved in regulating adult stem cell fate in various contexts. We show here that Cph is expressed in ISCs and EEs in the Drosophila intestine. Increased levels of Cph correlates with increased ISC proliferation and EE differentiation. cph loss-of-function leads to impaired ISC proliferation. Cph levels are elevated during tumourigenesis as well as in ageing and infection conditions. Knockdown of Cph in a Notch-mutant tumour model reduces tumour size and incidence and extends lifespan. Mechanistically, Cph overexpression leads to an increase in enteroendocrine (EE) cells and DamID DNA-binding and qRT-PCR analysis reveals that Cph directly regulates the levels of key EE regulatory genes such as Prospero (pros) and Phyllopod (phyl). In addition, Cph directly regulates core cell cycle regulators such as E2F1 as well as the TF Nerfin-1 that controls ISC proliferation and maintenance. Together, these data support a role for Cph in finetuning the balance between differentiation and proliferation during entero-endocrine differentiation.

developmental biology↗

bioRxiv2020

Eosinophil peroxidase induces inflammation in an animal model of dermatitis

Eosinophils play an important role in mediating itch and inflammation in dermatitis. The role of the eosinophil granule protein eosinophil peroxidase (EPX) in mediating inflammation and itch was tested in a dermatitis mouse model. Mice were sensitized to trimellitic anhydride (TMA) and subsequently challenged chronically on the ear to establish dermatitis. Loss of EPX (in EPX (-/-) mice) or blocking EPX with the drug resorcinol significantly reduced dermatitis in mice exposed to TMA. Resorcinol also reduced levels of thymic stromal lymphopoietin protein (TSLP) in skin. Further studies showed that EPX increased different cytokines in keratinocytes in cell culture via two distinct mechanisms. EPX induced TSLP expression requires lysophosphatidic acid signaling while EPX induced expression of TNF-, CSF2, CSF3, and IL1 required IL-1 signaling. We also showed that blocking IL-1 reduced inflammation in skin following TMA exposure in mice. Thus, EPX is an important mediator of inflammation and itch, that are mediated via at least two pathways. This suggests that both EPX and its signaling pathways may provide novel therapeutic strategies in dermatitis.

immunology↗