Biology subjects

Lamer, S.

Publications and source records attributed to Lamer, S..

4 recordsLinked to original sources

bioRxiv2025

Axon guidance deficits in a human sensory neuron model of Fabry disease

Fabry disease (FD) is a rare genetic galactosidase alpha (GLA) gene associated lysosomal disorder caused by alpha-galactosidase A (AGAL) deficiency, leading to sphingolipid (globotriaosylceramide, Gb3) accumulation in multiple tissues. Burning pain due to small fiber neuropathy is an early symptom with great impact on health- related quality of life. The pathophysiological role of Gb3 accumulations in sensory neurons of the dorsal root ganglia is incompletely understood. We have differentiated induced pluripotent stem cells of an isogenic GLA knockout line (p.S364del, hemizygous) and its healthy control into sensory neurons to model FD in vitro. We have compared both lines on transcriptional and proteomic level and investigated the effects of AGAL enzyme supplementation. FD sensory neurons showed dysregulation of disease-related pathways, including axon guidance at both RNA and protein level and microfluidic assays revealed shorter neurite length. While AGAL did not restore the transcriptomic state, it reduced Gb3 accumulation and lowered protein ephrin 5A and glycoprotein M6A level. These findings highlight axon guidance alterations in an isogenic human FD sensory model, with potential implications for early central and peripheral innervation in small fiber neuropathy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC="FIGDIR/small/673441v1_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@199cd19org.highwire.dtl.DTLVardef@682521org.highwire.dtl.DTLVardef@15da60borg.highwire.dtl.DTLVardef@1404c10_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Lentiviral-mediated gene complementation rescues pathogenic ABCA3 variants

The ATP-binding cassette subfamily A member 3 (ABCA3) protein on the limiting membrane of lamellar bodies in alveolar type 2 (AT2) cells transports phospholipids required for pulmonary surfactant assembly. ABCA3 deficiency results from biallelic pathogenic variants in ABCA3 and causes progressive neonatal respiratory failure or childhood interstitial lung disease (chILD). Supportive/compassionate care or lung transplantation are the only current definitive treatments for ABCA3 deficiency and progressive respiratory failure. Complementing dysfunctional ABCA3 by gene addition has therapeutic potential. Previous studies show that repairing or complementing ABCA3 in induced pluripotent stem cell (iPSC)-derived AT2 cells rescues lamellar body morphology and surfactant phospholipid composition. Pathogenic variants disrupt ABCA3 function through altered protein trafficking (type 1) or by impaired phospholipid transport (type 2) into lamellar bodies. Here we tested ABCA3 gene complementation using a human pulmonary epithelial cell line (A549) with a genomically silenced ABCA3 locus (ABCA3KO). From this line, additional cell lines that stably express individual ABCA3 variant cDNA constructs from a single genomic locus were tested: L101P (type 1), E292V (type 2), E690K (type 2), or wild-type ABCA3. Lentiviral-mediated ABCA3 delivery to each cell line partially rescued localization to LAMP3+ vesicles, lamellar body-like structure morphology, and cell proliferation. A functional assay measuring NF-{kappa}B signaling suggested that ABCA3 complementation ameliorated aberrant inflammatory signaling in E292V or E690K (type 2) mutant lines, but not in L101P (type 1) or knockout lines. These studies highlight the therapeutic potential of gene addition as well as differences between ABCA3 pathogenic variants that may influence genetic therapy outcomes.

molecular biology↗

bioRxiv2025

Murine cytomegalovirus evolved a cell-cycle regulator (m54.5) within the highly conserved viral DNA polymerase gene

Ribosome profiling (Ribo-seq) coupled with transcription start site profiling time-course analyses recently unveiled hundreds of novel viral gene products in lytic murine cytomegalovirus (MCMV) infection. One of these is the m54.5 open reading frame (ORF) located within the highly conserved viral DNA polymerase locus (M54). Interestingly, the m54.5 ORF is expressed from its own transcript (m54.5 RNA) with early gene expression kinetics, and at much higher levels than M54. In this study, we show that m54.5 encodes a nuclear viral protein (m54.5p) that contributes to cell cycle regulation during lytic MCMV infection. We show that m54.5p interacts with components of the anaphase-promoting complex/cyclosome (APC/C) and the phosphatase-6 (PP6) complex. Nocodazole mitotic arrest assays confirmed G1 cell cycle arrest and dysregulation by m54.5. Serum starvation revealed impaired cell cycle progression to S-phase. Notably, m54.5p is not conserved in other cytomegaloviruses but functionally mimics the UL21a protein of human cytomegalovirus (HCMV), which similarly targets the master cell cycle regulator APC/C to disrupt cell cycle progression. m54.5 thus represents convergent evolution to HCMV UL21a in MCMV within the highly conserved viral DNA polymerase gene. Nevertheless, we found that m54.5p is dispensable for viral replication in cultured mouse fibroblasts, indicative of redundant cell cycle regulation in lytic MCMV infection. These findings highlight a surprising genomic plasticity of herpesviruses, facilitating the evolution of an independent transcript encoding for a >200 aa gene product within a deeply conserved viral gene locus. Author SummarySystems biology approaches have revealed a surprising complexity of herpesvirus gene products. Using advanced sequencing approaches, we discovered a novel gene, m54.5, that independently evolved within a highly conserved region of the murine cytomegalovirus (MCMV) genome. This gene, which shows no conservation in other CMVs, produces a nuclear protein, m54.5p, abundantly expressed early during infection. We show that m54.5p interacts with host cell cycle regulators--the anaphase-promoting complex/cyclosome (APC/C) and phosphatase-6 (PP6)--to arrest cells in G1 phase and block progression into S phase. This function and underlying mechanism are reminiscent of the unrelated UL21a protein in human cytomegalovirus, illustrating how distinct viruses can evolve similar strategies to control host cell division. Despite its role in cell cycle disruption, m54.5p is not required for MCMV replication in cultured cells, suggesting redundant viral mechanisms. Our findings reveal an unexpected plasticity of herpesvirus genomes to evolve new, functional transcripts and proteins even within one of the most highly conserved genomic regions. Our findings thereby reshape our understanding of herpesvirus evolution and virus-host interaction.

microbiology↗

bioRxiv2025

Stable interaction of NONO with DBHS family members upon etoposide-induced DNA damage

The Non-POU domain containing octamer binding (NONO) protein is a member of the multifunctional Drosophila behavior/human splicing (DBHS) protein family and a core component of nuclear paraspeckles. NONO forms dimers with the other two DBHS members splicing factor proline and glutamine rich (SFPQ) protein or the paraspeckle component 1 (PSCP1) to modulate RNA metabolism and gene expression both at the transcriptional and post-transcriptional level. Increasing evidence suggests that NONO participates in genome maintenance by stimulating the DNA damage response (DDR) upon induction of DNA double-strand breaks (DSBs). However, the molecular principles that engage NONO in genome stability are poorly understood. We hypothesized that the induction of DSBs alters NONO protein-protein interactions and applied label-free mass spectrometry to test for changes in the interactome of NONO in human U2OS cells upon treatment with the topoisomerase II inhibitor etoposide. Surprisingly, our mass spectrometry data reveal that etoposide treatment does not induce major changes in NONO protein-protein interactions. We confirmed this finding by orthogonal co-immunoprecipitation assays and co-localization assays. Our data suggest that the bulk of interactions between NONO and SFPQ or PSPC1 are insensitive to etoposide treatment and that DBHS family members promote genome stability as stable dimers.

biochemistry↗