Biology subjects

Hovatta, I.

Publications and source records attributed to Hovatta, I..

5 recordsLinked to original sources

bioRxiv2024

Human iPSC-derived pericyte-like cells carrying APP Swedish mutation overproduce beta-amyloid and induce cerebral amyloid angiopathy-like changes

Alzheimers disease (AD) patients often exhibit cerebral amyloid angiopathy (CAA), i.e beta-amyloid (A{beta}) accumulation within cerebral blood vessels causing cerebrovascular dysfunction. Pericytes wrap around vascular capillaries, thus regulating cerebral blood flow, angiogenesis, and vessel stability. Vascular dysfunction can promote the development and progression of neurodegenerative diseases, yet the specific contribution of pericytes to AD pathology remains unclear. Here we show that human induced pluripotent stem cell (iPSC)-derived pericyte-like cells (iPLCs) can generate A{beta} peptides, and that the cells carrying Swedish mutation in amyloid precursor protein (APPswe) secrete 10 times more A{beta}1-42 than the control cells. Additionally, APPswe iPLCs have an impaired capacity to support angiogenesis and barrier integrity, exhibit a prolonged contractile response, and produce increased levels of pro-inflammatory cytokines upon inflammatory stimulation. These functional alterations in APPswe iPLCs are accompanied by transcriptional upregulation of actin cytoskeleton and extracellular matrix organization-related genes. Therefore, the APPswe mutation in iPLCs recapitulates several features of CAA pathology in vitro. Our iPSC-based vascular cell model may thus serve as a platform for drug discovery targeting vascular dysfunction in AD.

cell biology↗

bioRxiv2022

Mind the gap: Nodes of Ranvier are remodeled by chronic psychosocial stress and neuronal activity

Differential expression of myelin-related genes and changes in myelin thickness have been demonstrated in mice after chronic psychosocial stress, a risk factor for anxiety disorders. To determine whether and how stress affects structural remodeling of nodes of Ranvier, another form of myelin plasticity, we developed a 3D reconstruction analysis of node morphology in C57BL/6NCrl and DBA/2NCrl mice. We identified strain-dependent effects of chronic stress on node morphology, including elongation of paranodes in the medial prefrontal cortex (mPFC) in DBA/2NCrl mice. Furthermore, chronic chemogenetic activation of the ventral hippocampus-to-mPFC pathway resulted in increased risk assessment behavior and shortened paranodes specifically in stimulated axons, providing a direct link between anxiety-like behavior and remodeling of the nodes. Altogether, our data demonstrate genetic regulation of nodal remodeling in stress and suggest an activity-dependent regulation of paranodes in anxiety-related circuits. Nodal remodeling may thus contribute to the aberrant circuit function associated with anxiety disorders.

neuroscience↗

bioRxiv2020

Patient iPSC-astrocytes show transcriptional and functional dysregulation in schizophrenia

Human astrocytes are multifunctional brain cells and may contribute to the pathophysiology of schizophrenia (SCZ). We differentiated astrocytes from induced pluripotent stem cells of monozygotic twins discordant for SCZ, and found sex-specific gene expression and signaling pathway alterations related particularly to inflammation and synaptic functions. While Ingenuity Pathway Analysis identified SCZ disease and synaptic transmission pathway changes in SCZ astrocytes, the most consistent findings were related to collagen and cell adhesion associated pathways. Neuronal responses to glutamate and GABA differed between astrocytes from control persons, affected twins, and their unaffected co-twins, and were normalized by clozapine treatment. SCZ astrocyte cell transplantation to the mouse forebrain caused gene expression changes in demyelination, synaptic dysfunction and inflammation pathways of mouse brain cells and resulted in behavioral changes in cognitive and olfactory functions. Altogether, our results show that astrocytes contribute to both familial risk and clinical manifestation of SCZ in a sex-specific manner.

neuroscience↗

bioRxiv2018

Variants in regulatory elements of PDE4D associate with Major Mental Illness in the Finnish population

We have previously reported a replicable association between variants at the PDE4D gene and familial schizophrenia in a Finnish cohort. In order to identify the potential functional mutations alluded to by these previous findings, we sequenced the 1.5Mb of the PDE4D genomic locus in 20 families (consisting of 96 individuals, and 79 independent chromosomes), followed by two stages of genotyping across 6,668 individuals from multiple Finnish cohorts for major mental illnesses. We identified 4,570 SNPs across the PDE4D gene, with 380 associated to schizophrenia (p[≤]0.05). Importantly, two of these variants, rs35278 and rs165940, are located at transcription factor binding sites, and displayed replicable association in the two-stage enlargement of the familial schizophrenia cohort, (combined statistics for rs35278 p=0.0012; OR=1.18, 95% CI 1.06-1.32; and rs165940 p=0.0016; OR=1.27, 95% CI 1.13-1.41). Further analysis using additional cohorts and endophenotypes revealed that rs165940 principally associates within the psychosis (p=0.025, OR=1.18, 95% CI 1.07-1.30) and cognitive domains of major mental illnesses (g-score p=0.044, beta=-0.033). Specifically, the cognitive domains represented verbal learning and memory (p=0.0091, beta=-0.044) and verbal working memory (p=0.0062, beta=-0.036). Moreover, expression data from the GTEx database demonstrated that rs165940 significantly correlates with the mRNA expression levels of PDE4D in the cerebellum (p-value=0.04; m-value=0.9), demonstrating a potential functional consequence for this variant. Thus, rs165940 represents the most likely functional variant for major mental illness at the PDE4D locus in the Finnish population, increasing risk broadly to psychotic disorders.

genetics↗

bioRxiv2018

Genome-wide Association Study of Anxiety and Stress-related Disorders in the iPSYCH Cohort

Anxiety and stress-related disorders (ASRD) are among the most common mental disorders with the majority of patients suffering from additional disorders. Family and twin studies indicate that genetic and environmental factors are underlying their etiology. As ASRD are likely to configure various expressions of abnormalities in the basic stress-response system, we conducted a genome-wide association study including 12,655 cases with various anxiety and stress-related diagnoses and 19,225 controls. Standard association analyses were performed supplemented by a framework of sensitivity analyses. Variants in PDE4B showed consistent association with ASRD across a wide range of our analyses. In mice models, alternations in PDE4B expression were observed in those mice displaying anxious behavior after exposure to chronic stress. We also showed that 28% of the variance in ASRD was accounted for by common variants and that the genetic signature of ASRD overlapped with psychiatric traits, educational outcomes, obesity-related phenotypes, smoking, and reproductive success.

genetics↗