Biology subjects

Prokop, J.

Publications and source records attributed to Prokop, J..

6 recordsLinked to original sources

bioRxiv2026

Incomplete Reverse Remodeling of the Tricuspid Valve Leaflets Following Relief of Pressure Overload

Objective(s)Tricuspid valve (TV) remodeling and functional tricuspid regurgitation (FTR) progression during right ventricular (RV) pressure overload and reverse remodeling after resolution of RV afterload is poorly understood. We set out to investigate tricuspid leaflet tissue response to induction and subsequent alleviation of pressure overload in a large animal model of RV failure with FTR. MethodsFifteen healthy adult male Dorset sheep (72{+/-}4 kg) underwent pulmonary artery banding (PAB) to induce RV failure and FTR. After 8 weeks, 7 sheep (PAB, n=7) were terminated, and remaining 8 had the PAB removed (rPAB, n=8) and were followed for another 8 weeks before termination. Both groups underwent epicardial echocardiography and hemodynamic assessment during banding surgery and at terminal operation. Ten healthy sheep served as a control group (CTL, n=10) and underwent terminal procedure only. In all animals, TV leaflets and right ventricular (RV) tissue were harvested at terminal procedure and analyzed histologically and transcriptionally. ResultsTV leaflets in PAB animals showed increased cross-sectional area and ECM alterations, some of which persisted after resolution of RV pressure overload. rPAB valves exhibited distinct ECM composition, with notably altered mucin and fibrin content, suggesting a shift toward matrix stabilization, dissimilar to control and PAB. RNA sequencing uncovered a unique molecular state in rPAB valves, with persistent changes in PRG4, PDE3A, CXCL8, and HLA transcripts. RV tissue also demonstrated a separate remodeling trajectory, with sustained expression of stress-related genes including PDE3A, NAV2, ANFB, and ACTS. These findings indicate that both valve and ventricular tissues retain a persistent remodeled phenotype post-unloading. ConclusionsTV leaflets actively remodel in response to hemodynamic stress and do not fully revert to a normal state after relief of pressure overload. This persistent altered phenotype may represent a biological contribution of the TV leaflets to recurrent TR with implications for long-term outcomes following treatment of FTR. Clinical Perspective What is new?O_LIRelief of right ventricular pressure overload, in a large animal model, resulted in substantial reverse remodeling of the right heart and reduction of tricuspid regurgitation severity, but tricuspid valve leaflets did not return to a normal state. C_LIO_LIReverse remodeled leaflets remained enlarged despite normalization of hemodynamics with an altered extracellular matrix. C_LIO_LICellular proliferation and immune cell infiltration observed during pressure overload resolved after unloading, yet transcriptomic analysis identified a distinct molecular phenotype that differed from both healthy and diseased valves. C_LIO_LITricuspid valve leaflets are active biological participants in the remodeling process and exhibit persistent adaptation or maladaptation after resolution of the initiating hemodynamic stress. C_LI What Are the Clinical Implications?O_LISecondary tricuspid regurgitation should be considered a disease involving both right heart geometry and leaflet biology. C_LIO_LIResolution of the underlying cause of tricuspid regurgitation may not restore leaflet structure and molecular homeostasis. C_LIO_LIPersistent leaflet remodeling may contribute to residual or recurrent tricuspid regurgitation despite successful treatment of pulmonary hypertension or other inciting conditions. C_LIO_LITherapies directed at leaflet remodeling may ultimately complement surgical and transcatheter strategies currently focused on annular and ventricular geometry. C_LI

physiology↗

bioRxiv2025

The Tricuspid Valve is Transcriptionally Active During Prolonged Pressure Overload, Right-Sided Heart Failure, and Valve Regurgitation

BackgroundRight-sided heart failure (RHF), in the presence of tricuspid valve regurgitation (TR), can result from left-sided heart failure (LHF), pulmonary hypertension (PH), or heart malformations. The occurrence of RHF and TR represents a critical indicator of hospitalization rates and all-cause mortality. However, RHF has remained understudied, specifically with respect to the tricuspid valve, with few animal models to investigate the transformative processes and identify novel interventions. MethodsUsing the outbred sheep (Ovis aries) model of pulmonary artery banding (PAB) that induces RHF and TR, we generated three batches of ribosomal reduced RNA sequencing for 354 samples (NCBI SRA PRJNA1182691) containing right ventricle, left ventricle, each tricuspid valve leaflet, each mitral valve leaflet, and the pulmonary artery that represents both male and female sheep. The reads were assembled into a de novo sheep heart transcriptome for differential analysis. ResultsThe de novo sheep heart transcriptome enhanced transcript mapping of reads by 43-45% in the heart valves relative to the known sheep reference transcriptome. The identified transcripts produce validated tissue-specific pathways in ventricles (2,756 isoforms), pulmonary arteries (535 isoforms), and valves (1,215 isoforms), with transcript differences between the mitral and tricuspid valve involved in extracellular and endocrine signaling. The transcriptome also produced robust sex differences encoded by sex chromosomes and autosomes, highlighting epigenetic and sex hormone differences in the heart. Echocardiography and differential expression suggest that 8 weeks after PAB, the right ventricle has extensive morphological changes and known stress-induced lipid processing dysregulation. At 16-weeks post-PAB, tricuspid valve leaflets show the most significant transcriptional changes, with alterations in endocrine and immune pathway genes involved in cellular and extracellular remodeling. Genes within the tricuspid valve with differential expression and known human or mouse heart phenotypes include FLNA, LTBP4, VDR, CR2, PIGQ, CENPF, ACKR3, CR1, KLF2, and HIF3A. ConclusionsThis project highlights the complexity of heart valve tissues and their transcriptional activity in a sheep model of RHF. It suggests potential therapeutic interventions in heart valve remodeling in PAH, RHF, and TR. This work highlights the need for further human and model organism research into the dynamic valve cells and genes. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABS- Improved cardiac and valve specific transcriptome mapping through de novo transcriptome for clinically relevant ovine model. - Tricuspid valves show a sex dependent and active transcriptional response to pulmonary artery banding induced pulmonary hypertension and right sided heart failure. - Transcriptional phenotypes in ovine model mirror known human heart disease phenotypes. - Several transcripts identified with therapeutic potential for treating pressure overload conditions such as pulmonary hypertension. What Are the Clinical Implications?- Tricuspid valve remodeling due to pulmonary hypertension is accompanied by transcriptional alterations, and mechanical alterations alone may not be sufficient to address valve insufficiency. - Valve and ventricle sex specific gene expression changes following pulmonary hypertension indicate a potential role for hormonal influences and a need for personalized treatment strategies. - Improved patient outcomes for right heart failure, including diagnosis, early detection, and improved treatment strategies can be elucidated through the ovine model and supported through expanded interrogation of human tissues.

genomics↗

bioRxiv2023

Kit Ligand and Kit receptor tyrosine kinase sustain synaptic inhibition of Purkinje Cells

The cell-type specific expression of ligand/receptor and cell-adhesion molecules is a fundamental mechanism through which neurons regulate connectivity. Here we determine a functional relevance of the long-established mutually exclusive expression of the receptor tyrosine kinase Kit and the trans-membrane protein Kit Ligand by discrete populations of neurons in the mammalian brain. Kit is enriched in molecular layer interneurons (MLIs) of the cerebellar cortex (i.e., stellate and basket cells), while cerebellar Kit Ligand is selectively expressed by a target of their inhibition, Purkinje cells (PCs). By in vivo genetic manipulation spanning embryonic development through adulthood, we demonstrate that PC Kit Ligand and MLI Kit are required for, and capable of driving changes in, inhibition of PCs. Collectively, these works in mice demonstrate that the Kit Ligand/Kit receptor dyad sustains mammalian central synapse function and suggest a rationale for the affiliation of Kit mutation with neurodevelopmental disorders. Visual Abstract O_FIG O_LINKSMALLFIG WIDTH=192 HEIGHT=200 SRC="FIGDIR/small/542885v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1d53d9eorg.highwire.dtl.DTLVardef@c05c4borg.highwire.dtl.DTLVardef@eb58eeorg.highwire.dtl.DTLVardef@11b8431_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Bulk RNA-Sequencing of small airway cell cultures from IPF and post-COVID lung fibrosis patients illustrates disease signatures and differential responses to TGF-β1 treatment

IPF is a condition in which an injury to the lung leads to the accumulation of scar tissue. This fibrotic tissue reduces lung compliance and impairs gas exchange. Studies have shown that infection with COVID-19 significantly worsens the clinical outcomes of IPF patients. The exact etiology of IPF is unknown, but recent evidence suggests that the distal small airways, (those having a diameter less than 2 mm in adults), play a role in the early pathogenesis of IPF. TGF-{beta}1 is a main driver of fibrosis in a variety of tissues; the binding of TGF-{beta}1 to its receptor triggers a signaling cascade that results in inflammatory signaling, accumulation of collagen and other components of the extracellular matrix, and immune system activation. This study aimed to investigate possible mechanisms that contribute to worsening lung fibrosis in IPF patients after being diagnosed with COVID-19, with a particular focus on the role of TGF-{beta}1. Small airway cell cultures derived from IPF and post-COVID-19 IPF patient transplant tissues were submitted for RNA-sequencing and differential gene expression analysis. The genetic signatures for each disease state were determined by comparing the differentially expressed genes present in the cells cultured under control conditions to cells cultured with TGF-{beta}1. The genes shared between the culture conditions laid the framework for determining the genetic signatures of each disease. Our data found that genes associated with pulmonary fibrosis appeared to be more highly expressed in the post-COVID fibrosis samples, under both control and TGF-{beta}1-treated conditions. A similar trend was noted for genes involved in the TGF-{beta}1 signaling pathway; the post-COVID fibrosis cell cultures seemed to be more responsive to treatment with TGF-{beta}1. Gene expression analysis, RT-PCR, and immunohistochemistry confirmed increased levels of BMP signaling in the IPF small airway cell cultures. These findings suggest that TGF-{beta}1 signaling in IPF small airway cells could be inhibited by BMP signaling, leading to the differences in genetic signatures between IPF and post-COVID fibrosis.

cell biology↗

bioRxiv2022

Targeting ATP12A, a non-gastric proton pump alpha subunit, for idiopathic pulmonary fibrosis treatment

Idiopathic Pulmonary Fibrosis (IPF) is a pathological condition of unknown etiology which results from injury to the lung and an ensuing fibrotic response that leads to thickening of the alveolar walls and obliteration of the alveolar space. The pathogenesis is not clear and there are currently no effective therapies for IPF. Small airway disease and mucus accumulation are prominent features in IPF lungs, similar to Cystic Fibrosis (CF) lung disease. The ATP12A gene encodes the alpha-subunit of the non-gastric H+, K+-ATPase, which functions to acidify the airway surface fluid and impairs mucociliary transport function in cystic fibrosis patients. We hypothesize that the ATP12A protein may play a role in the pathogenesis of IPF. Our studies demonstrate that ATP12A protein is overexpressed in distal small airways from IPF patient lungs compared to normal human lungs. In addition, overexpression of the ATP12A protein in mouse lungs worsened the bleomycin (BLEO)-induced experimental pulmonary fibrosis. This was prevented by a potassium-competitive proton pump blocker, vonoprazan (VON). This data supports the concept that the ATP12A protein plays an important role in the pathogenesis of lung fibrosis. Inhibition of the ATP12A protein has the potential as a novel therapeutic strategy in IPF.

cell biology↗

bioRxiv2020

PEA15 loss of function and defective cerebral development in the domestic cat

Cerebral cortical size and organization are critical features of neurodevelopment and human evolution, for which genetic investigation in model organisms can provide insight into developmental mechanisms and the causes of cerebral malformations. However, some abnormalities in cerebral cortical proliferation and folding are challenging to study in laboratory mice due to the absence of gyri and sulci in rodents. We report an autosomal recessive allele in domestic cats associated with impaired cerebral cortical expansion and folding, giving rise to a smooth, lissencephalic brain, and that appears to be caused by homozygosity for a frameshift in PEA15 (phosphoprotein expressed in astrocytes-15). Notably, previous studies of a Pea15 targeted mutation in mice did not reveal structural brain abnormalities. Affected cats, however, present with a non-progressive hypermetric gait and tremors, develop dissociative behavioral defects and aggression with age, and exhibit profound malformation of the cerebrum, with a 45% average decrease in overall brain weight, and reduction or absence of the ectosylvian, sylvian and anterior cingulate gyrus. Histologically, the cerebral cortical layers are disorganized, there is substantial loss of white matter in tracts such as the corona radiata and internal capsule, but the cerebellum is relatively spared. RNA-seq and immunohistochemical analysis reveal astrocytosis. Fibroblasts cultured from affected cats exhibit increased TNF-mediated apoptosis, and increased FGFb-induced proliferation, consistent with previous studies implicating PEA15 as an intracellular adapter protein, and suggesting an underlying pathophysiology in which increased death of neurons accompanied by increased proliferation of astrocytes gives rise to abnormal organization of neuronal layers and loss of white matter. Taken together, our work points to a new role for PEA15 in development of a complex cerebral cortex that is only apparent in gyrencephalic species. SummaryGyrification is the neurodevelopmental process in certain mammalian species during which the cerebral cortex expands and folds resulting in the classic wrinkled appearance of the brain. Abnormalities in this process underlie many congenital malformations of the brain. However, unlike many other human malformations, genetic insight into gyrification is not possible in laboratory mice because rodents have a lissencephalic or smooth cerebral cortex. We identified a mutation in domestic cats that likely causes failure of the cerebral cortex to expand and fold properly, and discovered that the mutation impairs production of a protein, PEA15 (phosphoprotein expressed in astrocytes-15), involved in intracellular signaling. Affected cats have profound abnormalities in brain development, with minimal changes in their superficial behavior and neurologic function. Additional studies of tissue and cultured cells from affected animals suggest a pathophysiologic mechanism in which increased death of neurons accompanied by increased cell division of astrocytes gives rise to abnormal organization of neuronal layers and loss of white matter. These results provide new insight into a developmental process that is unique to animals with gyrencephalic brains.

genetics↗