Biology subjects

Bohlen, J. F.

Publications and source records attributed to Bohlen, J. F..

4 recordsLinked to original sources

bioRxiv2025

Characterization of astrocyte density in the Pitt-Hopkins Syndrome mouse model of ASD

Transcription factor 4 (TCF4) is a proneural basic helix-loop-helix transcription factor that plays a critical role in brain development and is associated with a variety of psychiatric disorders including autism spectrum disorder (ASD), major depressive disorder, and schizophrenia. Autosomal dominant mutations in TCF4 result in a profound neurodevelopmental disorder called Pitt-Hopkins Syndrome (PTHS). Germline TCF4 loss-of-function (LOF) studies using human and mouse models have identified dysregulation in neural cell proliferation, genesis, and specification which lead to disruption in neuronal, astroglial and oligodendroglial lineages. In this study, we focused on the role of TCF4 in the genesis of the astrocyte lineage, specifically in the context of modeling PTHS. We show that germline heterozygous mutations in Tcf4 had no effect on the expression of astrocyte marker genes in primary astrocyte cultures and whole brain lysates. Immunohistochemical (IHC) analysis of pan- and subclass-specific astrocyte markers showed Tcf4 mutation had no effect on the proportions of astrocytes in the dorsal cortex and corpus callosum. Lastly, we tracked ventrally-derived astrocytes using an Nkx2.1 reporter mouse and observed that germline Tcf4 LOF did not result in misallocation of ventrally-derived astrocytes into the dorsal cortex, a phenotype previously observed when both Tcf4 alleles were conditionally deleted in the Nkx2.1 lineage. These data indicate that germline heterozygous TCF4 LOF, which models PTHS, does not appear to affect the astrocyte lineage at the cell population level.

neuroscience↗

bioRxiv2023

TCF4 mutations disrupt synaptic function through dysregulation of RIMBP2 in patient-derived cortical neurons

Genetic variation in the transcription factor 4 (TCF4) gene is associated with risk for a variety of developmental and psychiatric conditions, which includes a syndromic form of ASD called Pitt Hopkins Syndrome (PTHS). TCF4 encodes an activity-dependent transcription factor that is highly expressed during cortical development and in animal models is shown to regulate various aspects of neuronal development and function. However, our understanding of how disease-causing mutations in TCF4 confer pathophysiology in a human context is lacking. Here we show that cortical neurons derived from patients with TCF4 mutations have deficits in spontaneous synaptic transmission, network excitability and homeostatic plasticity. Transcriptomic analysis indicates these phenotypes result from altered expression of genes involved in presynaptic neurotransmission and identifies the presynaptic binding protein, RIMBP2 as the most differentially expressed gene in PTHS neurons. Remarkably, TCF4-dependent deficits in spontaneous synaptic transmission and network excitability were rescued by increasing RIMBP2 expression in presynaptic neurons. Together, these results identify TCF4 as a critical transcriptional regulator of human synaptic development and plasticity and specifically identifies dysregulation of presynaptic function as an early pathophysiology in PTHS.

neuroscience↗

bioRxiv2022

Clemastine fumarate enhances myelination and promotes functional recovery in a syndromic ASD mouse model of Pitt-Hopkins Syndrome

Pitt-Hopkins syndrome (PTHS) is an autism spectrum disorder (ASD) caused by autosomal dominant mutations in the Transcription Factor 4 gene (TCF4). One pathobiological process caused by Tcf4 mutation is a cell autonomous reduction in oligodendrocytes (OLs) and myelination. In this study, we show that clemastine is effective at restoring myelination defects in a PTHS mouse model. In vitro, clemastine treatment reduced excess oligodendrocyte precursor cells (OPCs) and normalized OL density. In vivo, two-week intraperitoneal administration of clemastine also normalized OPC and OL density in the cortex of Tcf4 mutant mice and appeared to increase the number of axons undergoing myelination, as EM imaging of the corpus callosum showed a significant increase in uncompacted myelin. Importantly, this treatment paradigm resulted in functional rescue by improving electrophysiology and behavior. Together, these results provide preclinical evidence that remyelination therapies may be beneficial in PTHS and potentially other neurodevelopmental disorders characterized by demyelination.

neuroscience↗

bioRxiv2017

Defects of myelination are common pathophysiology in syndromic and idiopathic autism spectrum disorders

Autism spectrum disorder (ASD) affects approximately 1:68 individuals and has incalculable burdens on affected individuals, their families, and health care systems. While the genetic contributions to idiopathic ASD are heterogeneous and largely unknown, the causal mutations for syndromic forms of ASD - including truncations and copy number variants - provide a genetic toehold with which to gain mechanistic insights1-3. Models of these syndromic disorders have been used to better characterize the molecular and physiological processes disrupted by these mutations4. Two fundamental questions remain - how biologically similar are the mouse models of syndromic forms of ASD, and how relevant are these mouse models to their human analogs? To address these questions, we performed integrative transcriptomic analyses of seven independent mouse models of three syndromic forms of ASD generated across five laboratories, and assessed dysregulated genes and their pathways in human postmortem brain from patients with ASD and unaffected controls. These cross-species analyses converged on shared disruptions in myelination and axon development across both syndromic and idiopathic ASD, highlighting both the face validity of mouse models for these disorders and identifying novel convergent molecular phenotypes amendable to rescue with therapeutics.

neuroscience↗