scholarly journals Depletion of Cholesteryl Esters Causes Meibomian Gland Dysfunction-Like Symptoms in a Soat1-Null Mouse Model

2021 ◽  
Vol 22 (4) ◽  
pp. 1583
Author(s):  
Igor A. Butovich ◽  
Amber Wilkerson ◽  
Seher Yuksel

Previous studies on ablation of several key genes of meibogenesis related to fatty acid elongation, omega oxidation, and esterification into wax esters have demonstrated that inactivation of any of them led to predicted changes in the meibum lipid profiles and caused severe abnormalities in the ocular surface and Meibomian gland (MG) physiology and morphology. In this study, we evaluated the effects of Soat1 ablation that were expected to cause depletion of the second largest class of Meibomian lipids (ML)—cholesteryl esters (CE)—in a mouse model. ML of the Soat1-null mice were examined using liquid chromatography high-resolution mass spectrometry and compared with those of Soat1+/− and wild-type mice. Complete suppression of CE biosynthesis and simultaneous accumulation of free cholesterol (Chl) were observed in Soat1-null mice, while Soat1+/− mutants had normal Chl and CE profiles. The total arrest of the CE biosynthesis in response to Soat1 ablation transformed Chl into the dominant lipid in meibum accounting for at least 30% of all ML. The Soat1-null mice had clear manifestations of dry eye and MG dysfunction. Enrichment of meibum with Chl and depletion of CE caused plugging of MG orifices, increased meibum rigidity and melting temperature, and led to a massive accumulation of lipid deposits around the eyes of Soat1-null mice. These findings illustrate the role of Soat1/SOAT1 in the lipid homeostasis and pathophysiology of MG.

2020 ◽  
Vol 4 (s1) ◽  
pp. 95-95
Author(s):  
Sunita N Misra ◽  
Theresa M. Czech ◽  
Jennifer A. Kearney

OBJECTIVES/GOALS: Variants in voltage-gated sodium channels (VGSC) are a common cause of severe early onset epilepsy. Changes in CSF neurotransmitters (NT) were identified in 2 cases of VGSC-related epilepsy. Here we investigate NT changes in patients and a novel mouse model of VGSC-related epilepsy. METHODS/STUDY POPULATION: We conducted a single site IRB approved retrospective chart review of patients with VGSC-related epilepsy who underwent CSF NT testing for diagnostic purposes. In parallel, we examined NT levels from the brains of wild-type (WT) and a novel VGSC-related epilepsy mouse model after obtaining IACUC approval. We rapidly isolated forebrain, cortex, striatum, and brainstem from 5-6 animals per sex and genotype. A combination of HPLC with electrochemical detection and mass spectrometry were used to quantify NT levels from brain samples. RESULTS/ANTICIPATED RESULTS: We identified 10 patients with VGSC-related epilepsy who received CSF NT testing. Two of these patients had abnormal NT results including changes to dopamine (DA) or serotonin (5-HT) metabolites. We analyzed NT levels from four brain regions from male and female WT and VGSC-related epilepsy mice. We anticipate that most of the NT levels will be similar to WT, however subtle changes in the DA or 5-HT metabolites may be seen in VGSC-related epilepsy. DISCUSSION/SIGNIFICANCE OF IMPACT: Patients with VGSC-related epilepsy often have autism spectrum disorder, sleep, and movement disorders. Understanding the role of aberrant NT levels in VGSC-related epilepsy may provide additional therapeutic targets that address common neuropsychological comorbidities as well as seizures.


2004 ◽  
Vol 279 (50) ◽  
pp. 52390-52398 ◽  
Author(s):  
Steven P. Anderson ◽  
Paul Howroyd ◽  
Jie Liu ◽  
Xun Qian ◽  
Rainer Bahnemann ◽  
...  

The nuclear receptor peroxisome proliferator-activated receptor α (PPARα), in addition to regulating lipid homeostasis, controls the level of tissue damage after chemical or physical stress. To determine the role of PPARα in oxidative stress responses, we examined damage after exposure to chemicals that increase oxidative stress in wild-type or PPARα-null mice. Primary hepatocytes from wild-type but not PPARα-null mice pretreated with the PPAR pan-agonist WY-14,643 (WY) were protected from damage to cadmium and paraquat. The livers from intact wild-type but not PPARα-null mice were more resistant to damage after carbon tetrachloride treatment. To determine the molecular basis of the protection by PPARα, we identified by transcript profiling genes whose expression was altered by a 7-day exposure to WY in wild-type and PPARα-null mice. Of the 815 genes regulated by WY in wild-type mice (p≤ 0.001; ≥1.5-fold or ≤-1.5-fold), only two genes were regulated similarly by WY in PPARα-null mice. WY increased expression of stress modifier genes that maintain the health of the proteome, including those that prevent protein aggregation (heat stress-inducible chaperones) and eliminate damaged proteins (proteasome components). Although the induction of proteasomal genes significantly overlapped with those regulated by 1,2-dithiole-3-thione, an activator of oxidant-inducible Nrf2, WY increased expression of proteasomal genes independently of Nrf2. Thus, PPARα controls the vast majority of gene expression changes after exposure to WY in the mouse liver and protects the liver from oxidant-induced damage, possibly through regulation of a distinct set of proteome maintenance genes.


2021 ◽  
Vol 15 ◽  
Author(s):  
Valerie Wai ◽  
Lauren Roberts ◽  
Jana Michaud ◽  
Leah R. Bent ◽  
Andrea L. Clark

Afferent neurons and their mechanoreceptors provide critical sensory feedback for gait. The anatomical distribution and density of afferents and mechanoreceptors influence sensory feedback, as does mechanoreceptor function. Electrophysiological studies of hind paw skin reveal the different types of afferent responses and their receptive fields, however, the anatomical distribution of mechanoreceptor endings is unknown. Also, the role of integrin α1β1 in mechanoreceptor function is unclear, though it is expressed by keratinocytes in the stratum basale where it is likely involved in a variety of mechanotransduction pathways and ion channel functionalities. For example, it has been shown that integrin α1β1 is necessary for the function of TRPV4 that is highly expressed by afferent units. The purpose of this study, therefore, was to determine and compare the distribution of mechanoreceptors across the hind paw skin and the footfall patterns of itga1-null and wild type mice. The itga1-null mouse is lacking the integrin α1 subunit, which binds exclusively to the β1 subunit, thus rendering integrin α1β1 nonfunctional while leaving the numerous other pairings of the β1 subunit undisturbed. Intact hind paws were processed, serially sectioned, and stained to visualize mechanoreceptors. Footfall patterns were analyzed as a first step in correlating mechanoreceptor distribution and functionality. Merkel cells and Meissner-like corpuscles were present, however, Ruffini endings and Pacinian corpuscles were not observed. Meissner-like corpuscles were located exclusively in the glabrous skin of the footpads and digit tips, however, Merkel cells were found throughout hairy and glabrous skin. The increased density of Merkel cells and Meissner-like corpuscles in footpads 1 and 3 and Meissner-like corpuscles in footpad 4 suggests their role in anteroposterior balance, while Meissner-like corpuscle concentrations in digits 2 and 5 support their role in mediolateral balance. Finally, a larger density of Meissner-like corpuscles in footpads 3 and 4 in male itga1-null mice compared to wild type controls paves the way for future site-specific single fiber in vivo recordings to provide insight into the role of integrin α1β1 in tactile mechanotransduction.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3933-3933
Author(s):  
Kushani Shah ◽  
Zhenhua Yang ◽  
Robert Whitaker ◽  
Theodore Busby ◽  
Jing Hu ◽  
...  

Abstract Epigenetic modulators have emerged as promising targets for treating cancers, especially blood cancers. As the major histone H3K4 methylation enzymes in mammals, the Set1/Mll complexes represent potential drug targets in epigenetic therapeutics due to the intimate connection of H3K4 methylation with gene expression and their extensive association with multiple cancers including blood cancers. However, the functional role for the Set1/Mll complexes in tumorigenesis remains incompletely understood, and the potential of pharmacologically targeting the H3K4 methylation activity of these complexes has not been fully explored. The Set1/Mll complexes comprise one of six different catalytic subunits and several shared core subunits including Dpy30. We have previously shown that Dpy30 directly facilitates genome-wide H3K4 methylation, and plays a crucial role in fundamental cellular processes including proliferation and differentiation. Using a conditional Dpy30 KO mouse model that was recently generated in our laboratory, we have established a critical role of Dpy30 in hematopoietic stem cell differentiation and long-term maintenance (Yang et al., J Exp Med, accepted). Although Dpy30 is a global epigenetic modulator, our data show that Dpy30 loss in the hematopoietic system has a much more profound impact on the H3K4me3 at hematopoietic genes than on genes associated with fundamental cellular pathways. Moreover, we have shown that reducing Dpy30 level by heterozygosity significantly suppresses Eμ-myc-driven lymphomagenesis without affecting normal physiology or life span (ASH meeting 2015 Abstract #310), suggesting a role for Dpy30 as a non-oncogene addiction pathway for cancer and a possible therapeutic window for targeting Dpy30 in potential cancer treatment. As we previously demonstrated that Dpy30 knockdown abolished the growth and colony-formation capacity of several MLL-rearranged leukemia cell lines, we sought to further investigate the role of Dpy30 in leukemogenesis and leukemia stem cell (LSC) function in animals. To this end, we have established a MLL-AF9-driven leukemogenesis mouse model by transducing bone marrow from our conditional Dpy30 KO mice with MLL-AF9 virus and transplanting these cells into recipient mice. Our results clearly demonstrated that inducing Dpy30 deletion in the recipients abrogated leukemia progress. We are currently testing the role of Dpy30 in LSC function by transplantation of MLL-AF9 transduced leukemia cells with the CAG-CreER; Dpy30F/Fbackground. Mild Dpy30 depletion (~50% reduction) is induced in the secondary recipients to examine the possible effects on LSC function, considering that 50% reduction of Dpy30 level (as seen in our Dpy30 heterozygous mice) does not affect normal physiology. We next sought to design inhibitors of Dpy30 activity for treating blood cancer. Dpy30 associates with and enhances the methylation activity of Set1/Mll complexes by directly binding to the Ash2l subunit. We have designed and synthesized a cell-permeable peptidomimetic corresponding to the Dpy30-binding region on Ash2l, as well as a mutant peptidomimetic that fails to bind to Dpy30 and serves as a negative control. We have shown that, although both effectively penetrated cells, only the wild-type but not mutant peptidomimetic successfully inhibited Dpy30's biochemical activity in enhancing H3K4 methylation, markedly reduced the intracellular binding of Dpy30 to the Mll complexes, and impaired Dpy30 recruitment to its genomic targets. Continuous treatment of the wild-type, but not the mutant, peptidomimetic also inhibited the growth of leukemia cells. Our results strongly suggest that pharmacological inhibition of Dpy30's activity in Set1/Mll complexes can suppress tumor cell growth. We are currently optimizing peptidomimetics to increase the intracellular stability and improve the inhibitory effect on leukemia growth. Taken together, our studies have established an important role of Dpy30 in the MLL-rearranged leukemogenesis, and demonstrate a proof-of-principle for pharmacologically targeting Dpy30's activity in potential treatment of hematological malignancies. Disclosures No relevant conflicts of interest to declare.


2006 ◽  
Vol 75 (1) ◽  
pp. 452-461 ◽  
Author(s):  
Nisheeth Agarwal ◽  
Samuel C. Woolwine ◽  
Sandeep Tyagi ◽  
William R. Bishai

ABSTRACT Alternate sigma factors have been implicated in the survival of mycobacteria in response to specific stresses. To characterize the role of SigM in Mycobacterium tuberculosis, a sigM deletion mutant was generated by allelic exchange in the virulent CDC1551 strain. Comparing the wild-type and ΔsigM strains by complete genomic microarray, we observed a low level of baseline expression of sigM in wild-type M. tuberculosis and no significant differences in the gene expression patterns between these two strains. Alternatively, a SigM-overexpressing M. tuberculosis strain was constructed and microarray profiling revealed SigM-dependent expression of a relatively small group of genes, which included four esat-6 homologues: esxE, esxF, esxT, and esxU. An assessment of SigM-dependent promoters from the microarray analysis revealed a putative consensus sequence for M. tuberculosis SigM of −35 GGAAC and −10 CGTCR. In vitro expression studies showed that M. tuberculosis sigM transcripts accumulate slightly in stationary phase and following heat shock. To understand the role of SigM in pathogenesis, the M. tuberculosis sigM deletion strain was compared with the isogenic wild-type strain and the complemented mutant strain for survival in murine macrophages and in the mouse model. The mutant was found to have similar abilities to survive in both the resting and activated J774A.1 macrophages. Mouse organ bacterial burdens indicated that the mutant proliferated and persisted at the same level as that of the wild-type and complemented strains in lung and spleen tissues. In time-to-death experiments in the mouse model, the ΔsigM mutant exhibited lethality times comparable to those observed for the wild-type and complemented strains. These data indicate that M. tuberculosis SigM governs the expression of a small set of genes, including four esat-6 homologues, and that the loss of sigM does not confer a detectable virulence defect in the macrophages and mouse models of infection.


2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Wey-Ran Lin ◽  
Siew-Na Lim ◽  
Tzung-Hai Yen ◽  
Malcolm R. Alison

This study aimed to understand the role of IL-10 secreted from bone marrow (BM) in a mouse model of pancreatic fibrosis. The severity of cerulein-induced inflammation, fibrosis, and the frequency of BM-derived myofibroblasts were evaluated in the pancreas of mice receiving either a wild-type (WT) BM or an IL-10 knockout (KO) BM transplantation. The area of collagen deposition increased significantly in the 3 weeks after cerulein cessation in mice with an IL-10 KO BM transplant (13.7 ± 0.6% and 18.4 ± 1.1%,p< 0.05), but no further increase was seen in WT BM recipients over this time. The percentage of BM-derived myofibroblasts also increased in the pancreas of the IL-10 KO BM recipients after cessation of cerulein (6.7 ± 1.1% and 11.9 ± 1.3%,p< 0.05), while this figure fell in WT BM recipients after cerulein withdrawal. Furthermore, macrophages were more numerous in the IL-10 KO BM recipients than the WT BM recipients after cerulein cessation (23.2 ± 2.3 versus 15.3 ± 1.7 per HPF,p< 0.05). In conclusion, the degree of fibrosis, inflammatory cell infiltration, and the number of BM-derived myofibroblasts were significantly different between IL-10 KO BM and WT BM transplanted mice, highlighting a likely role of IL-10 in pancreatitis.


Blood ◽  
2007 ◽  
Vol 110 (7) ◽  
pp. 2423-2431 ◽  
Author(s):  
Patricia Redecha ◽  
Rachel Tilley ◽  
Michael Tencati ◽  
Jane E. Salmon ◽  
Daniel Kirchhofer ◽  
...  

Fetal loss in patients with antiphospholipid (aPL) antibodies has been ascribed to thrombosis of placental vessels. However, we have shown that inflammation, specifically activation of complement with generation of the anaphylotoxin C5a, is an essential trigger of fetal injury. In this study, we analyzed the role of the procoagulant molecule tissue factor (TF) in a mouse model of aPL antibody–induced pregnancy loss. We found that either blockade of TF with a monoclonal antibody in wild-type mice or a genetic reduction of TF prevented aPL antibody–induced inflammation and pregnancy loss. In response to aPL antibody–generated C5a, neutrophils express TF potentiating inflammation in the deciduas and leading to miscarriages. Importantly, we showed that TF in myeloid cells but not fetal-derived cells (trophoblasts) was associated with fetal injury, suggesting that the site for pathologic TF expression is neutrophils. We found that TF expression in neutrophils contributes to respiratory burst and subsequent trophoblast injury and pregnancy loss induced by aPL antibodies. The identification of TF as an important mediator of C5a-induced oxidative burst in neutrophils in aPL-induced fetal injury provides a new target for therapy to prevent pregnancy loss in the antiphospholipid syndrome.


PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0245143
Author(s):  
Anna-Karina B. Maier ◽  
Nadine Reichhart ◽  
Johannes Gonnermann ◽  
Norbert Kociok ◽  
Aline I. Riechardt ◽  
...  

Tumor necrosis factor (TNF)α is an inflammatory cytokine likely to be involved in the process of corneal inflammation and neovascularization. In the present study we evaluate the role of the two receptors, TNF-receptor (TNF-R)p55 and TNF-Rp75, in the mouse model of suture-induced corneal neovascularization and lymphangiogenesis. Corneal neovascularization and lymphangiogenesis were induced by three 11–0 intrastromal corneal sutures in wild-type (WT) C57BL/6J mice and TNF-Rp55-deficient (TNF-Rp55d) and TNF-Rp75-deficient (TNF-Rp75d) mice. The mRNA expression of VEGF-A, VEGF-C, Lyve-1 and TNFα and its receptors was quantified by qPCR. The area covered with blood- or lymphatic vessels, respectively, was analyzed by immunohistochemistry of corneal flatmounts. Expression and localization of TNFα and its receptors was assessed by immunohistochemistry of sagittal sections and Western Blot. Both receptors are expressed in the murine cornea and are not differentially regulated by the genetic alteration. Both TNF-Rp55d and TNF-Rp75d mice showed a decrease in vascularized area compared to wild-type mice 14 days after suture treatment. After 21 days there were no differences detectable between the groups. The number of VEGF-A-expressing macrophages did not differ when comparing WT to TNF-Rp55d and TNF-Rp75d. The mRNA expression of lymphangiogenic markers VEGF-C or LYVE-1 does not increase after suture in all 3 groups and lymphangiogenesis showed a delayed effect only for TNF-Rp75d. TNFα mRNA and protein expression increased after suture treatment but showed no difference between the three groups. In the suture-induced mouse model, TNFα and its ligands TNF-Rp55 and TNF-Rp75 do not play a significant role in the pathogenesis of neovascularisation and lymphangiogenesis.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2493-2493
Author(s):  
Yutein Chung ◽  
Huiyan Jin ◽  
Claire Trasorras ◽  
Francina Gonzalez ◽  
Sang Hee Min

Primary Myelofibrosis (PMF) is a chronic myeloproliferative disorder characterized by excessive bone marrow (BM) fibrosis that can lead to ineffective hematopoiesis and reduced survival. PMF patients develop several megakaryocyte (MK) abnormalities including increased proliferation, abnormal morphology and upregulated expression of pro-fibrotic genes. Although several studies support the role of MK in BM fibrosis, the significance of MK in the development of BM fibrosis has not been demonstrated in vivo. Here, we investigated the in vivo role of MK in the pathogenesis of BM fibrosis. First, we reproduced an established bone marrow transplantation (BMT) mouse model of PMF. To achieve this, lethally irradiated wild-type mice were transplanted with wild-type hematopoietic stem cells (HSC) transduced with either MPLW515L gene construct (MPLW515L BMT) or MIGR1 empty vector (MIGR1 BMT). Consistent with previous studies, starting at day 14 post-BMT, MPLW515L BMT mice gradually developed increased number of leukocytes and platelets, increased proliferation of abnormal megakaryocytes in the BM and spleen, hepatosplenomegaly with extra-medullary hematopoiesis, and reticulin fibrosis in the BM. Notably, robust fibrosis was also seen in the spleen and liver. Next, to study the significance of MK in the development of BM fibrosis, we developed a MPLW515L BMT mouse model in which MK lineage could be selectively ablated. We accomplished this using PF4-Cre inducible diphtheria toxin receptor transgenic mice (iDTR+/-/PF4-Cre) as BMT donors. HSCs from iDTR+/-/PF4-Cre mice were transduced with MPLW515L or MIGR1 empty vector and transplanted as described above. Beginning day 14 post-BMT, recipient mice were injected with diphtheria toxin (DT) or water every 48 hours. At day 20 and day 29, DT injection significantly depleted MK in both MPLW515L BMT and MIGR1 BMT groups compared to water injection. Importantly, DT-injected MPLW515L BMT mice displayed attenuated fibrosis in the BM, spleen, and liver compared to water-injected MPLW515L BMT mice. In addition, DT treatment decreased the level of alpha smooth muscle actin in both BM and spleen of MPLW515L BMT mice, which suggests that MKs are critical for myofibroblast differentiation. MK ablation did not leukocytosis, thrombocytosis or hepatosplenomegaly. Together, our study show that successful MK ablation in vivo reduces fibrosis development in the BM, spleen, and liver of the MPLW515L mouse model of PMF. In summary, these results support the essential role of MK in the pathogenesis of BM fibrosis in PMF. Further studies are underway to elucidate the mechanisms by which MK contribute to fibrosis in PMF. Disclosures No relevant conflicts of interest to declare.


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