Biology subjects

Leidinger, M. R.

Publications and source records attributed to Leidinger, M. R..

7 recordsLinked to original sources

bioRxiv2025

Deficiency of Mesencephalic Astrocyte-derived Neurotrophic Factor Aggravates Acute Pancreatitis in Mice

Acute pancreatitis (AP) is a complex and potentially severe inflammatory disorder of the pancreas and is one of the most common causes of gastrointestinal hospitalization. Although environmental risk factors such as alcohol and gallstones are well recognized, only a subset of exposed individuals develop AP, suggesting that intrinsic factors, including genetic susceptibility, influence disease onset and progression. Endoplasmic reticulum (ER) stress has emerged as a key mechanism in AP pathogenesis, because ER is essential for protein synthesis, folding, degradation and secretion (proteostasis). Mesencephalic astrocyte-derived neurotrophic factor (MANF), an ER stress-inducible protein highly expressed in the pancreas, plays a critical role in maintaining proteostasis, yet its involvement in AP remains unclear. To investigate the functional role of MANF in AP, we generated pancreas-specific MANF knockout (MANF-KO) mice using the Cre/loxP system and subjected them to moderate experimental AP, that is caerulein- or alcohol-induced AP in mice. In the caerulein model, MANF deficiency exacerbated pancreatic injury in both sexes, as indicated by increased apoptosis (cleaved caspase-3, caspase-12), ER stress markers (eIF2, p-eIF2, GRP78), inflammation (IL-6, TNF), regenerative activity (Ki67), and pancreatic lipase levels. Notably, male MANF-KO mice exhibited enhanced inflammation (HMGB1), macrophage infiltration (CD68), and oxidative stress (DNP, HNE), which were not observed in females. In the alcoholic AP model, both male and female MANF-KO mice showed increased ER stress (p-IRE1, p-eIF2, GRP78), apoptosis, inflammation, macrophage infiltration, regeneration, and lipase levels, whereas elevated HMGB1 expression and oxidative stress again predominantly occurred in male MANF-KO mice. Together, these findings reveal a critical and sex-specific role for MANF in regulating pancreatic stress responses and inflammatory injury, supporting its potential contribution as a genetic factor in AP pathogenesis.

pathology↗

bioRxiv2025

Spatial Transcriptomics Analysis Uncovers ER stress in MANF-deficient Purkinje Cells Underlying Alcohol-induced Cerebellar Vulnerability in Mice

Cerebellar Purkinje cells (PCs) are among the most vulnerable neurons to alcohol neurotoxicity. Alcohol can induce endoplasmic reticulum (ER) stress and alter the structure and function of PCs. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an ER stress inducible protein highly expressed in PCs. It is neuroprotective in various pathological conditions where ER stress is induced. However, it is unknown whether MANF plays a role in protecting PCs from alcohol induced ER stress. In this study, we generated PC-specific MANF knockout (KO) mouse model to test the hypothesis that MANF deficient PCs are more susceptible to binge alcohol exposure induced ER stress and neurodegeneration in the adult brain. We found that PC-specific MANF KO animals show moderate motor function deficit, which was exacerbated by alcohol exposure. Interestingly, female KOs were more sensitive than male KOs to alcohol-induced motor function impairments. In accordance with the behavior changes, alcohol exposure also caused UPR activation, increased intranuclear expression of calcium binding protein Calbindin, and PC degeneration in female but not male MANF KO mice. Spatial transcriptomics and high throughput in situ analyses demonstrated that MANF deficiency altered the transcriptomic landscape in PCs in a sex-specific manner and triggered the expression of genes involved in protein folding and response to ER stress. These results suggests that MANF KO PCs may be predisposed with a higher risk to UPR activation and ER stress in a sex dependent manner, contributing to their vulnerability to alcohol neurotoxicity.

molecular biology↗

bioRxiv2022

Mice expressing P301S mutant human tau have deficits in interval timing

Interval timing is a key executive process that involves estimating the duration of an interval over several seconds or minutes. Patients with Alzheimers disease (AD) have deficits in interval timing. Since temporal control of action is highly conserved across mammalian species, studying interval timing tasks in animal AD models may be relevant to human disease. Amyloid plaques and tau neurofibrillary tangles are hallmark features of AD. While rodent models of amyloid pathology are known to have interval timing impairments, to our knowledge, interval timing has not been studied in models of tauopathy. Here, we evaluate interval timing performance of P301S transgenic mice, a widely studied model of tauopathy that overexpresses human tau with the P301S mutation. We employed the switch interval timing task, and found that P301S mice consistently underestimated temporal intervals compared to wild-type controls, responding early in anticipation of the target interval. Our study indicating timing deficits in a mouse tauopathy model could have relevance to human tauopathies such as AD. HIGHLIGHTSO_LIWe examined interval timing behavior in mice expressing P301S mutant tau C_LIO_LIP301S mice responded earler than littermate controls C_LIO_LIThese data provide insight into animal models of tauopathy C_LI

neuroscience↗

bioRxiv2021

Oncogenic RABL6A promotes NF1-associated MPNST progression in vivo

BackgroundMalignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that display complex molecular and genetic alterations. Powerful tumor suppressors CDKN2A and TP53 are commonly disrupted in these lesions along with NF1, a gene that encodes a negative regulator of Ras. Many additional factors have been implicated in MPNST pathogenesis. A greater understanding of critical drivers of the disease is needed to guide more informed targeted therapies for patients. RABL6A is a newly identified driver of MPNST cell survival and proliferation whose in vivo role in the disease is unknown. MethodsUsing CRISPR-Cas9 targeting of Nf1+Cdkn2a or Nf1+Tp53 in the sciatic nerve to form de novo MPNSTs, we investigated the biological significance of RABL6A in MPNST development. Molecular evaluation of terminal tumors (western blot, qRT-PCR, immunohistochemistry) yielded several insights. ResultsMice lacking Rabl6 displayed slower tumor growth and extended survival relative to wildtype animals in both genetic contexts. YAP oncogenic activity was selectively downregulated in RABL6A-null, Nf1+Cdkn2a lesions but not in RABL6A-null, Nf1+Tp53 tumors. Regardless of genetic context, loss of RABL6A caused upregulation of the CDK inhibitor, p27 in tumors. Paradoxically, both models displayed elevated Myc protein expression and Ki67 staining in terminal tumors lacking RABL6A. ConclusionsThese findings demonstrate RABL6A is required for optimal tumor progression of NF1 mutant MPNSTs in vivo in both Cdkn2a and p53 inactivated settings. However, sustained RABL6A loss may provide selective pressure for molecular alterations, such as Myc upregulation, that ultimately promote an unwanted, hyper-proliferative tumor phenotype akin to drug resistant lesions. Importance of the StudyMPNSTs are aggressive, deadly, and challenging to treat tumors due to location around nerves and high mutational burden. Many factors implicated in MPNST genesis have yet to be fully tested for biological significance in disease formation. We establish a critical physiological role for a new oncoprotein, RABL6A, in promoting NF1-associated MPNST progression. We identify novel RABL6A-regulated pathways that likely contribute to tumor growth, specifically YAP and Myc signaling, and found that sustained RABL6A loss eventually yields more proliferative tumors. We liken RABL6A deficient tumors to those being treated with therapies targeting RABL6A effectors, such as CDKs. Therefore, those lesions should provide a powerful platform to uncover key mediators of drug resistance. Our data suggest oncogenic YAP and Myc could be such mediators of resistance. This study provides a novel system to examine one of the most pressing clinical challenges, drug resistant tumor growth and relapse, in cancer therapy.

cancer biology↗

bioRxiv2021

RABL6A promotes pancreatic neuroendocrine tumor angiogenesis and progression in vivo

Pancreatic neuroendocrine tumors (pNETs) are difficult-to-treat neoplasms whose incidence is rising. Greater understanding of pNET pathogenesis is needed to identify new biomarkers and targets for improved therapy. RABL6A, a novel oncogenic GTPase, is highly expressed in patient pNETs and required for pNET cell proliferation and survival in vitro. Here, we investigated the role of RABL6A in pNET progression in vivo using a well-established model of the disease. RIP-Tag2 (RT2) mice develop functional pNETs (insulinomas) due to SV40 large T-antigen expression in pancreatic islet {beta} cells. RABL6A loss in RT2 mice significantly delayed pancreatic tumor formation, reduced tumor angiogenesis and mitoses, and extended survival. Those effects correlated with upregulation of anti-angiogenic p19ARF and downregulation of proangiogenic c-Myc in RABL6A-deficient islets and tumors. Our findings demonstrate that RABL6A is a bona fide oncogenic driver of pNET angiogenesis and development in vivo.

cancer biology↗

bioRxiv2020

K18-hACE2 Mice for Studies of COVID-19 Treatments and Pathogenesis Including Anosmia

The ongoing COVID-19 pandemic is associated with substantial morbidity and mortality. While much has been learned in the first months of the pandemic, many features of COVID-19 pathogenesis remain to be determined. For example, anosmia is a common presentation and many patients with this finding show no or only minor respiratory signs. Studies in animals experimentally infected with SARS-CoV-2, the cause of COVID-19, provide opportunities to study aspects of the disease not easily investigated in human patients. COVID-19 severity ranges from asymptomatic to lethal. Most experimental infections provide insights into mild disease. Here, using K18-hACE2 mice that we originally developed for SARS studies, we show that infection with SARS-CoV-2 causes severe disease in the lung, and in some mice, the brain. Evidence of thrombosis and vasculitis was detected in mice with severe pneumonia. Further, we show that infusion of convalescent plasma (CP) from a recovered COVID-19 patient provided protection against lethal disease. Mice developed anosmia at early times after infection. Notably, while treatment with CP prevented significant clinical disease, it did not prevent anosmia. Thus K18-hACE2 mice provide a useful model for studying the pathological underpinnings of both mild and lethal COVID-19 and for assessing therapeutic interventions.

microbiology↗

bioRxiv2020

Heterogeneous expression of the SARS-Coronavirus-2 receptor ACE2 in the human respiratory tract

BackgroundZoonotically transmitted coronaviruses are responsible for three disease outbreaks since 2002, including the current COVID-19 pandemic, caused by SARS-CoV-2. Its efficient transmission and range of disease severity raise questions regarding the contributions of virus-receptor interactions. ACE2 is a host ectopeptidase and the receptor for SARS-CoV-2. Numerous reports describe ACE2 mRNA abundance and tissue distribution; however, mRNA abundance is not always representative of protein levels. Currently, there is limited data evaluating ACE2 protein and its correlation with other SARS-CoV-2 susceptibility factors. Materials and methodsWe systematically examined the human upper and lower respiratory tract using single-cell RNA sequencing and immunohistochemistry to determine receptor expression and evaluated its association with risk factors for severe COVID-19. FindingsOur results reveal that ACE2 protein is highest within regions of the sinonasal cavity and pulmonary alveoli, sites of presumptive viral transmission and severe disease development, respectively. In the lung parenchyma, ACE2 protein was found on the apical surface of a small subset of alveolar type II cells and colocalized with TMPRSS2, a cofactor for SARS-CoV2 entry. ACE2 protein was not increased by pulmonary risk factors for severe COVID-19. Additionally, ACE2 protein was not reduced in children, a demographic with a lower incidence of severe COVID-19. InterpretationThese results offer new insights into ACE2 protein localization in the human respiratory tract and its relationship with susceptibility factors to COVID-19. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSPrevious studies of ACE2 mRNA transcript abundance in the human respiratory tract have suggested a possible association between ACE2 expression and age, sex, and the presence of comorbidities. However, these studies have provided conflicting results, as well as a lack of protein validation. Previous ACE2 protein studies have been limited by a paucity of lung tissue samples and reports that have produced contradictory results. Added value of this studyUsing a combination of single-cell RNA sequencing and immunohistochemistry, we describe ACE2 expression in the human respiratory tract. Staining protocols were optimized and validated to show consistent apical localization and avoid non-specific staining. We show ACE2 protein is found in subsets of airway cells and is highest within regions of the sinonasal cavity and pulmonary alveoli, sites of presumptive viral transmission and severe disease development for COVID-19, respectively. We show age, sex, and comorbidities do not increase ACE2 protein expression in the human respiratory tract. Implications of all the available evidenceACE2 protein abundance does not correlate with risk factors for severe clinical outcomes, but in some cases showed an inversed relationship. Features driving COVID-19 susceptibility and severity are complex, our data suggests factors other than ACE2 protein abundance as important determinants of clinical outcomes.

cell biology↗