Biology subjects

Kruger, K.

Publications and source records attributed to Kruger, K..

5 recordsLinked to original sources

bioRxiv2026

Monoclonal nephritic factors reveal insights into C3 convertase dynamics and dysregulation

C3- and C5-nephritic factors are potent but poorly understood autoantibodies that dysregulate complement convertases. To date, their underlying mechanisms of action, epitopes, and sequences remain unknown. To address this knowledge gap, we immune profiled B cells from a nephritic factor-positive C3 glomerulopathy patient and identified the first monoclonal C3- and C5-nephritic factors. We present the structure of a C3-nephritic factor bound to a C3 convertase with the convertase protease domain unexpectedly rotated and inhibited. This rotation advances our understanding of complement convertase progression and decay, explains disease-associated convertase variants, and reveals the molecular mechanism by which nephritic factors can either activate or inhibit convertase activity. We also detail heterogeneity within and between C3- and C5-nephritic factors in terms of convertase binding, stabilizing capacity, regulator inhibition, fluid-phase activation, and disease contribution. These findings improve stratification of patients with C3 glomerulopathy, redefine basic C3 convertase dynamics, and provide insights into antibody-mediated modulation of the complement system.

immunology↗

bioRxiv2024

Effects of fire and fire-induced changes in soil properties on post-burn soil respiration

BackgroundBoreal forests cover vast areas of land in the northern hemisphere and store large amounts of carbon (C) both aboveground and belowground. Wildfires, which are a primary ecosystem disturbance of boreal forests, affect soil C via combustion and transformation of organic matter during the fire itself, and via changes in plant growth and microbial activity post-fire. Wildfire regimes in many areas of the boreal forests of North America are shifting towards more frequent and severe fires driven by changing climate. As wildfire regimes shift and the effects of fire on belowground microbial community composition are becoming clearer, there is a need to link fire-induced changes in soil properties to changes in microbial functions such as respiration in order to better predict the impact of future fires on C cycling. ResultsWe used laboratory burns to simulate boreal crown fires on both organic-rich and sandy soil cores collected from Wood Buffalo National Park, Alberta, Canada, to measure the effects of burning on soil properties including pH, total C, and total nitrogen (N). We used 70-day soil incubations and two-pool exponential decay models to characterize the impacts of burning and its resulting changes in soil properties on soil respiration. Laboratory burns successfully captured a range of soil temperatures that were realistic for natural wildfire events. We found that burning increased pH and caused small decreases in C:N in organic soil. Overall, respiration per gram total (post-burn) C in burned soil cores was 16% lower than in corresponding unburned control cores, indicating that soil C lost during a burn may be partially offset by burn-induced decreases in respiration rates. Simultaneously, burning altered how remaining C cycled, causing an increase in the proportion of C represented in the modelled slow-cycling vs. fast-cycling C pool as well as an increase in fast-cycling C decomposition rates. ConclusionsTogether, our findings imply that C storage in boreal forests following wildfires will be driven by the combination of C losses during the fire itself as well as fire-induced changes to the soil C pool that modulate post-fire respiration rates. Moving forward, we will pair these results with soil microbial community data to understand how fire-induced changes in microbial community composition may influence respiration.

ecology↗

bioRxiv2023

Age-related phenotypes in breast cancer: a population- based study

Breast cancer in young (<40 years) is associated with a higher frequency of aggressive tumor types and poor prognosis. It remains unclear if there is an underlying age-related biology that contributes to the unfavorable outcome. We aim to investigate the relationship between age and breast cancer biology, with emphasis on proliferation. Clinico-pathologic information, immunohistochemical markers, and follow-up data were obtained for all patients aged <50 (Bergen cohort-1; n=355) and compared to previously obtained information on patients aged 50-69 (Bergen cohort-2; n=540), who participated in the Norwegian Breast Cancer Screening Program. Data from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) was applied for validation and for analyses of gene expression signatures. Young breast cancer patients presented more aggressive tumor features such as hormone receptor negativity, HER2 positivity, lymph-node metastasis, the HER2-enriched and triple negative subtypes, and shorter survival. Age <40 was significantly associated with features of stemness and higher proliferation (by Ki67), also in molecular subsets. Ki67 showed weaker prognostic value in young patients. We point to aggressive phenotypes, increased tumor cell proliferation and stem-like features in breast cancer of the young. Hence, tumors of young breast cancer patients may have a unique biology, also when accounting for screen/interval differences, that may open for new clinical opportunities, stratifying treatment by age.

pathology↗

bioRxiv2022

Neurogenesis and angiogenesis are associated features of aggressive breast cancer

The tumor microenvironment (TME) is important for cancer growth and progression. While angiogenesis is an established hallmark of cancer, the role of nerve fibers is less studied. Here, we investigated neurogenesis and angiogenesis in breast cancer and found them to be closely associated. Single-cell based spatial mapping by imaging mass cytometry (IMC) indicated close proximity between neural and vascular structures. Subsequent validation by tissue-based markers of neurogenesis and angiogenesis, supported by proteomics and transcriptomics data of tissues and cell lines, supported a link between these processes. A consolidated neuro-angiogenic signature score was linked to high-grade breast cancer and reduced patient survival, also within the low-grade luminal tumor subgroup. Our findings support that neurogenesis and angiogenesis are related in aggressive breast cancer and might possibly improve tumor stratification and clinical management.

cancer biology↗

bioRxiv2019

Development of the mandibular curve of Spee and maxillary compensating curve: A finite element model

The curved planes of the human dentition seen in the sagittal view, the mandibular curve of Spee and the maxillary compensating curve, have clinical importance to modern dentistry and potential relevance to the craniofacial evolution of hominins. However, the mechanism providing the formation of these curved planes is poorly understood. To explore this further, we use a simplified finite element model, consisting of maxillary and mandibular \"blocks\", developed to simulate tooth eruption, and forces opposing eruption, during simplified masticatory function. We test our hypothesis that curved occlusal planes develop from interplay between tooth eruption, occlusal load, and mandibular movement.\n\nOur results indicate that our simulation of rhythmic chewing movement, tooth eruption, and tooth eruption inhibition, applied concurrently, results in a transformation of the contacting maxillary and mandibular block surfaces from flat to curved. The depth of the curvature appears to be dependent on the radius length of the rotating (chewing) movement of the mandibular block. Our results suggest mandibular function and maxillo-mandibular spatial relationship may contribute to the development of human occlusal curvature.

developmental biology↗