Biology subjects

Lacruz, R. S.

Publications and source records attributed to Lacruz, R. S..

3 recordsLinked to original sources

bioRxiv2025

Elevated mitochondrial metabolism in Down syndrome iPSCs reduces commitment to neuroectoderm

A key feature of Down syndrome (DS) is reduced neurogenesis. Here, we provide evidence that increased mitochondrial metabolism in DS stem cells reduces their ability to commit to neuroectoderm (NE), one of the earliest steps in the development of the nervous system. We show that mitochondria in induced pluripotent stem cells derived from individuals with DS (3S-iPSCs) have a higher membrane potential and increased capacity for calcium uptake via the mitochondrial calcium uniporter (MCU) compared to isogenic, euploid controls. Consequently, 3S-iPSCs proliferate faster and spend less time in G1 of the cell cycle. This reduces the opportunity for growth of a primary cilium, an important developmental signaling hub. Inhibiting MCU or slowing proliferation of 3S-iPSCs is sufficient to increase ciliation and improve commitment to NE. In summary, we provide evidence that a mitochondria-to-cilia signaling axis important during the earliest steps of neurogenesis is dysregulated in DS, yet remains amenable to small molecule intervention.

developmental biology↗

bioRxiv2024

Regulatory T cells and IFN-γ-producing Th1 cells play a critical role in the pathogenesis of Sjögren's Syndrome

ObjectivesSjogrens Disease (SjD) is an autoimmune disorder characterized by progressive dysfunction, inflammation and destruction of salivary and lacrimal glands, and by extraglandular manifestations. Its etiology and pathophysiology remain incompletely understood, though a role for autoreactive B cells has been considered key. Here, we investigated the role of effector and regulatory T cells in the pathogenesis of SjD. MethodsHistological analysis, RNA-sequencing and flow cytometry were conducted on glands, lungs, eyes and lymphoid tissues of mice with regulatory T cell-specific deletion of stromal interaction proteins (STIM) 1 and 2 (Stim1/2Foxp3), which play key roles in calcium signaling and T cell function. The pathogenicity of T cells from Stim1/2Foxp3mice was investigated through adoptively transfer into lymphopenic host mice. Additionally, single-cell transcriptomic analysis was performed on peripheral blood mononuclear cells (PBMCs) of patients with SjD and control subjects. ResultsStim1/2Foxp3 mice develop a severe SjD-like disorder including salivary gland (SG) and lacrimal gland (LG) inflammation and dysfunction, autoantibodies and extraglandular symptoms. SG inflammation in Stim1/2Foxp3 mice is characterized by T and B cell infiltration, and transcriptionally by a Th1 immune response that correlates strongly with the dysregulation observed in patients with SjD. Adoptive transfer of effector T cells from Stim1/2Foxp3 mice demonstrates that the SjD-like disease is driven by interferon (IFN)-{gamma} producing autoreactive CD4+ T cells independently of B cells and autoantiboodies. scRNA-seq analysis identifies increased Th1 responses and attenuated memory Treg function in PBMCs of patients with SjD. ConclusionsWe report a more accurate mouse model of SjD while providing evidence for a critical role of Treg cells and IFN-{gamma} producing Th1 cells in the pathogenesis of SjD, which may be effective targets for therapy.

immunology↗

bioRxiv2024

Loss of STIM1 and STIM2 in salivary glands disrupts ANO1 function but does not induce Sjogren's disease

Sjogrens disease (SjD) is an autoimmune disease characterized by xerostomia (dry mouth), lymphocytic infiltration into salivary glands and the presence of SSA and SSB autoantibodies. Xerostomia is caused by hypofunction of the salivary glands and has been involved in the development of SjD. Saliva production is regulated by parasympathetic input into the glands initiating intracellular Ca2+ signals that activate the store operated Ca2+ entry (SOCE) pathway eliciting sustained Ca2+ influx. SOCE is mediated by the STIM1 and STIM2 proteins and the ORAI1 Ca2+ channel. However, there are no studies on the effects of lack of STIM1/2 function in salivary acini in animal models and its impact on SjD. Here we report that male and female mice lacking Stim1 and Stim2 (Stim1/2K14Cre) in salivary glands showed reduced intracellular Ca2+ levels via SOCE in parotid acini and hyposalivate upon pilocarpine stimulation. Bulk RNASeq of the parotid glands of Stim1/2K14Cre mice showed a decrease in the expression of Stim1/2 but no other Ca2+ associated genes mediating saliva fluid secretion. SOCE was however functionally required for the activation of the Ca2+ activated chloride channel ANO1. Despite hyposalivation, ageing Stim1/2K14Cre mice showed no evidence of lymphocytic infiltration in the glands or elevated levels of SSA or SSB autoantibodies in the serum, which may be linked to the downregulation of the toll-like receptor 8 (Tlr8). By contrast, salivary gland biopsies of SjD patients showed increased STIM1 and TLR8 expression, and induction of SOCE in a salivary gland cell line increased the expression of TLR8. Our data demonstrate that SOCE is an important activator of ANO1 function and saliva fluid secretion in salivary glands. They also provide a novel link between SOCE and TLR8 signaling which may explain why loss of SOCE does not result in SjD.

physiology↗