Sauerwein, T. | bioRxiv Science

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

Early posttranscriptional response to tetracycline exposure in a gram-negative soil bacterium reveals unexpected attenuation mechanism of a DUF1127 gene

The Gram-negative, soil-dwelling plant symbiont Sinorhizobium meliloti shares its free-living habitat with antibiotic producers. To learn about early steps of its adaptation to antibiotics, we analyzed transcriptome changes after 10 min exposure to subinhibitory amount of tetracycline (Tc). RNA-seq revealed 297 differentially expressed genes. Besides ten upregulated ribosomal genes, there was no recognizable functional pattern in the observed changes. Instead, upregulated genes were mostly first in operons and often small, while downregulated genes were downstream in operons. Furthermore, we detected mRNA stabilization upon Tc exposure for several up- and down-regulated genes. Thus, mRNA stabilization contributed to increased mRNA levels, but for downstream genes its effect was counteracted by premature transcriptional termination caused by disrupted coupling between transcription and translation. Using reporter constructs, we found that a DUF1127 gene, showing highest mRNA increase, is controlled by transcription attenuation depending on the translation of an upstream ORF (uORF). Our data suggest the following model: The attenuation strongly depends on the accessibility of C-rich codons at the begin of the uORF. The accessibility is guaranteed by translation of the uORF, and is possible in a time window after a ribosome moves downstream and before a next ribosome occupies the ribosomal binding site (RBS). The accessibility is blocked either by impaired translation initiation or, in the absence of ribosome binding, by base-pairing between the RBS and the C-rich codons. We propose that this is used by bacteria to monitor ribosome availability and translation efficiency, and to ensure reciprocal expression of the DUF1127 gene.

molecular biology↗