Biology subjects

Tybulewicz, V.

Publications and source records attributed to Tybulewicz, V..

11 recordsLinked to original sources

bioRxiv2025

PD-L2 Regulates Natural Antibody and IL-10 Secretion by B-1 cells

B-1 cells are innate-like lymphocytes that play a critical role in homeostasis by secreting natural antibodies, typically IgM, and immunosuppressive molecules such as IL-10. However, the regulation of these processes in B-1 cells remains poorly understood. Here, we demonstrate that PD-L2, a surface receptor expressed by all B-1 cells, regulates B-1 cell effector functions. We show that in contrast to the Mus musculus castaneus mouse and other mammals, commonly used laboratory mouse strains have a mutation resulting in a premature stop codon and hence a truncated PD-L2 lacking an intracellular domain. By reverting this mutation, we generated mice expressing full-length PD-L2 containing an intracellular domain. Using these, we found that PD-L2 signaling via the intracellular domain increases IL-10 secretion and decreases natural IgM secretion by B-1 cells, potentially due to reduced expression of plasma cell identity genes Blimp-1 and IRF4. These findings indicate direct cell-cell interaction-dependent regulation of B-1 cell effector functions mediated by PD-L2 signaling into B-1 cells.

immunology↗

bioRxiv2023

Congenital heart defects in Down syndrome are caused by increased dosage of DYRK1A

Down syndrome (DS), trisomy 21, is a gene dosage disorder which results in multiple phenotypes including congenital heart defects (CHD). This clinically important pathology is caused by a third copy of one or more of the [~]230 genes on human chromosome 21 (Hsa21), but the identity of the causative dosage-sensitive genes is unknown and hence pathological mechanisms remain obscure. We show that embryonic hearts from human fetuses with DS and mouse models of DS have reduced expression of mitochondrial respiration and cell proliferation genes correlating with CHD. Using systematic genetic mapping, we determine that three copies of the Dyrk1a gene, encoding a serine/threonine protein kinase, are required to cause CHD. Reducing Dyrk1a copy number from three to two reverses defects in proliferation and mitochondrial respiration in embryonic cardiomyocytes and rescues septation defects in DS hearts. Furthermore, treatment of pregnant mice with a DYRK1A inhibitor developed for clinical use partially reduces the incidence of CHD among Dp1Tyb embryos. Thus, increased dosage of DYRK1A is required to impair mitochondrial function and cause CHD in DS, revealing a therapeutic target for this common human condition. One Sentence SummaryIncreased dosage of DYRK1A causes mitochondrial dysfunction and congenital heart defects in Down syndrome and is ameliorated in utero by a drug.

developmental biology↗

bioRxiv2022

Craniofacial dysmorphology in Down Syndrome is caused by increased dosage of Dyrk1a and at least three other genes

Down syndrome (DS), trisomy of human chromosome 21 (Hsa21), occurs in 1 in 800 live births and is the most common human aneuploidy. DS results in multiple phenotypes, including craniofacial dysmorphology, characterised by midfacial hypoplasia, brachycephaly and micrognathia. The genetic and developmental causes of this are poorly understood. Using morphometric analysis of the Dp1Tyb mouse model of DS and an associated genetic mouse genetic mapping panel, we demonstrate that four Hsa21-orthologous regions of mouse chromosome 16 contain dosage-sensitive genes that cause the DS craniofacial phenotype, and identify one of these causative genes as Dyrk1a. We show that the earliest and most severe defects in Dp1Tyb skulls are in bones of neural crest (NC) origin, and that mineralisation of the Dp1Tyb skull base synchondroses is aberrant. Furthermore, we show that increased dosage of Dyrk1a results in decreased NC cell proliferation and a decrease in size and cellularity of the NC-derived frontal bone primordia. Thus, DS craniofacial dysmorphology is caused by increased dosage of Dyrk1a and at least three other genes. Summary statementCraniofacial dysmorphology in mouse models of Down syndrome is caused by increased dosage of at least four genes including Dyrk1a, resulting in reduced proliferation of neural crest-derived cranial bone progenitors.

developmental biology↗

bioRxiv2022

T cell migration requires ion and water influx to regulate actin polymerization

Migration of T cells is essential for their ability to mount immune responses. Chemokine-induced T cell migration requires WNK1, a kinase that regulates ion influx into the cell. However, it is not known why ion entry is necessary for T cell movement. Here we show that signaling from the chemokine receptor CCR7 leads to activation of WNK1 and its downstream pathway at the leading edge of migrating CD4+ T cells, resulting in ion influx and water entry by osmosis. We propose that WNK1-induced water entry is required to swell the membrane at the leading edge, generating space into which actin filaments can polymerize, thereby facilitating forward movement of the cell. Given the broad expression of WNK1 pathway proteins, our study suggests that ion and water influx are likely to be essential for migration in many cell types, including leukocytes and metastatic tumor cells. One Sentence SummaryChemokine-induced migration of T cells requires water entry at the leading edge to facilitate actin polymerization.

immunology↗

bioRxiv2022

Water influx is required for CD4+ T cell activation and T cell-dependent antibody responses

Signaling from the T cell antigen receptor (TCR) on CD4+ T cells plays a critical role in adaptive immune responses by inducing T cell activation, proliferation, and differentiation. We demonstrate that WNK1, a kinase implicated in osmoregulation in the kidney, is required in T cells to support T-dependent antibody responses. WNK1-deficient CD4+ T cells are severely impaired in their ability to proliferate and to generate antigen-specific T follicular helper cells in response to immunization with a T-dependent antigen. We show that WNK1 and its downstream OXSR1 and STK39 kinases are required for TCR signaling in CD4+ T cells and for entry into cell cycle. Additionally, by preventing ATR activation, this pathway is required for T cells to progress from G2 into M phase of the cell cycle. Unexpectedly, we show that this WNK1 pathway regulates water influx, most likely through AQP3, which is required for TCR-induced signaling and cell cycle entry. Thus, TCR signaling via WNK1, OXSR1, STK39 and AQP3 leads to water entry that is essential for CD4+ T cell proliferation and hence T cell-dependent antibody responses. Given the broad expression of WNK1, WNK1-dependent water influx may be a common feature of mitogenic pathways in many cell types, both within the immune system and beyond. One Sentence SummaryT cell antigen receptor signaling via the WNK1 kinase causes water entry which is essential for CD4+ T cell proliferation.

immunology↗

bioRxiv2022

Genetic mapping of APP and amyloid-β biology modulation by trisomy 21

Individuals who have Down syndrome frequently develop early onset Alzheimers disease, a neurodegenerative condition caused by the build-up of aggregated amyloid-{beta} and tau proteins in the brain. Amyloid-{beta} is produced by APP, a gene located on chromosome 21. People who have Down syndrome have three copies of chromosome 21 and thus also an additional copy of APP; this genetic change drives the early development of Alzheimers disease in these individuals. Here we use a combination of next-generation mouse models of Down syndrome (Tc1, Dp3Tyb, Dp(10)2Yey and Dp(17)3Yey) and a knockin mouse model of amyloid-{beta} accumulation (AppNL-F) to determine how chromosome 21 genes other than APP modulate APP/amyloid-{beta} in the brain when in three copies. We demonstrate that three copies of other chromosome 21 genes are sufficient to partially ameliorate amyloid-{beta} accumulation in the brain. We go on to identify a subregion of chromosome 21 that contains the gene/genes causing this decrease in amyloid-{beta} accumulation and investigate the role of two lead candidate genes Dyrk1a and Bace2. Thus an additional copy of chromosome 21 genes, other than APP, can modulate APP/amyloid-{beta} in the brain under physiological conditions. This work provides critical mechanistic insight into the development of disease and an explanation for the typically later age of onset of dementia in people who have AD-DS compared to those who have familial AD caused by triplication of APP.

neuroscience↗

bioRxiv2020

Memory-like B cells emerging from germinal centres recycle through the subcapsular sinus

Infection or vaccination leads to the development of germinal centers (GCs) where B cells evolve high affinity antigen receptors, eventually producing antibody-forming plasma cells or memory B cells. We followed the migratory pathways of B cells emerging from germinal centers (BEM) and found that many migrated into the lymph node subcapsular sinus (SCS) guided by sphingosine-1-phosphate (S1P). From there, B cells may exit the lymph node to enter distant tissues. Some BEM cells interacted with and took up antigen from SCS macrophages, followed by CCL21-guided return towards the GC. Disruption of local CCL21 gradients inhibited the recycling of BEM cells and resulted in less efficient adaption to antigenic variation. Our findings suggest that the recycling of BEM cells, that transport antigen and that contain the genetic code for B cell receptor variants, may support affinity maturation to antigenic drift.

immunology↗

bioRxiv2020

Critical role of WNK1 in MYC-dependent early thymocyte development

WNK1, a kinase that controls kidney salt homeostasis, also regulates adhesion and migration in CD4+ T cells. Wnk1 is highly expressed in thymocytes, and since migration is important for thymocyte maturation, we investigated a role for WNK1 in thymocyte development. We find that WNK1 is required for the transition of double negative (DN) thymocytes through the {beta}-selection checkpoint and subsequent proliferation and differentiation into double positive (DP) thymocytes. Furthermore, we show that WNK1 negatively regulates LFA1-mediated adhesion and positively regulates CXCL12-induced migration in DN thymocytes. Despite this, migration defects of WNK1-deficient thymocytes do not account for the developmental arrest. Instead, we show that in DN thymocytes WNK1 transduces pre-TCR signals via OXSR1 and STK39 kinases and the SLC12A2 ion co-transporter that are required for post-transcriptional upregulation of MYC and subsequent proliferation and differentiation into DP thymocytes. Thus, a pathway regulating ion homeostasis is a critical regulator of thymocyte development.

immunology↗

bioRxiv2019

Species-specific developmental timing is associated with global differences in protein stability in mouse and human

What determines the pace of embryonic development? Although many molecular mechanisms controlling developmental processes are evolutionarily conserved, the speed at which these operate can vary substantially between species. For example, the same genetic programme, comprising sequential changes in transcriptional states, governs the differentiation of motor neurons in mouse and human, but the tempo at which it operates differs between species. Using in vitro directed differentiation of embryonic stem cells to motor neurons, we show that the programme runs twice as fast in mouse as in human. We provide evidence that this is neither due to differences in signalling, nor the genomic sequence of genes or their regulatory elements. Instead, we find an approximately two-fold increase in protein stability and cell cycle duration in human cells compared to mouse. This can account for the slower pace of human development, indicating that global differences in key kinetic parameters play a major role in interspecies differences in developmental tempo.

developmental biology↗

bioRxiv2019

A landmark-free morphometric pipeline: Application to characterise a Down syndrome model skull phenotype

Characterising phenotypes often requires quantification of anatomical shapes. Quantitative shape comparison (morphometrics) traditionally uses anatomical landmarks and is therefore limited by the number of landmarks and operator accuracy when landmarks are located manually. Here we apply a landmark-free method to characterise the craniofacial skeletal phenotype of the Dp1Tyb mouse model of Down syndrome (DS), validating it against a landmark-based approach. We identify cranial dysmorphologies in Dp1Tyb mice, especially smaller size and brachycephaly (front-back shortening) homologous to the human phenotype. The landmark-free phenotyping was less labour-intensive and required less user training than the landmark-based method. It also enabled mapping of local differences as planar expansion or shrinkage. This higher resolution and local mapping pinpointed reductions in interior mid-snout structures and occipital bones in this DS model that were not as apparent using a traditional landmark-based method. This approach could make morphometrics widely-accessible beyond traditional niches in zoology and palaeontology, especially in characterising mutant phenotypes.

genetics↗

bioRxiv2018

Plasmodium-specific atypical memory B cells are not part of the long-lived memory response

A subset of atypical memory B cells accumulates in malaria and several infections, autoimmune disorders and aging in both humans and mice. It has been suggested these cells are exhausted long-lived memory B cells, and their accumulation may contribute to poor acquisition of long-lasting immunity to certain chronic infections, such as malaria and HIV. Here, we generated an immunoglobulin heavy chain knock-in mouse with a BCR that recognizes MSP1 of the rodent malaria parasite, Plasmodium chabaudi. In combination with a mosquito-initiated P. chabaudi infection, we show that Plasmodium-specific atypical memory B cells are short-lived and disappear upon natural resolution of chronic infection. These cells show features of activation, proliferation, DNA replication, and plasmablasts. Our data demonstrate that Plasmodium-specific atypical memory B cells are not a subset of long-lived memory B cells, but rather short-lived activated cells, and part of a physiologic ongoing B-cell response.

microbiology↗