Biology Open最新文献

Rod photoreceptor stability is critical for retinal health and lifelong vision. Rhodopsin (Rho) trafficking is essential for rod homeostasis, as its mislocalization precedes rod cell death in inherited retinal disorders such as retinitis pigmentosa. Despite its importance, the molecular mechanisms of Rho trafficking in mammalian rods remain largely undefined. We investigated Rho's subcellular organization in the mammalian rod Golgi complex. We utilized STORM and structured illumination microscopy super-resolution imaging to map Golgi proteins with Rho in mouse and macaque rods. Our analysis found that a large proportion of Rho in this subcellular region colocalizes with Rab6a in the trans-Golgi. To functionally test this interaction, we utilized a dominant-negative Rab6a mutant in HEK293T cells and mouse rods. The mutant significantly inhibits Rho secretion in cell culture, causing intracellular retention. In mouse rods, the mutant similarly causes significant trans-Golgi Rho retention; however, a majority of Rho protein still escaped the Golgi and reached the outer segment. Together, these findings uncover critical new subcellular details about Rho organization at the Golgi and establish a role for Rab6a as a regulator of Rho protein release from the trans-Golgi in mammalian rods. Our results provide critical insight into the protein trafficking mechanisms essential for long-term photoreceptor health.

Collagen is the most abundant protein in the human body, providing structural stability to connective tissues. It organises and interacts with other proteins to form a complex extracellular matrix (ECM), with loss of collagen in the ECM seen in diseases such as osteoarthritis and osteoporosis. As collagen, and other ECM components, are atypically large proteins, they require specific endoplasmic reticulum (ER) export machinery. A key player in the export of procollagen from the ER is the MIA3 gene product, TANGO1. We introduced mutations to both tango1 isoforms in zebrafish independently to understand the importance of the previously unexplored short isoform in zebrafish development and tissue homeostasis. We show that the long isoform of tango1 (tango1L) is mostly able to compensate for loss of the short isoform (tango1S) in larvae. However, non-collagenous components of the ECM (such as proteoglycans) were disrupted during development, leading to abnormal matrix patterning, visible by electron microscopy. Adult tango1S zebrafish show altered spinal morphology and changes to intervertebral discs, suggesting that tango1S plays a role in skeletal patterning and homeostasis that is independent of the long isoform.

Juvenile pikeperch (Sander lucioperca) undergo several ontogenetic shifts, the timing of which determines the survival of their first winter. The shift from planktivory to a more active piscivorous phenotype involves moving from pelagic to demersal habitat with more stimuli and hence potential brain functional reorganizations. During two consecutive years, we collected planktivores and piscivores with different body sizes between the years, recording distinct stages relative to the shift, and analyzed their whole-brain transcriptomes in an ecological context. We identified a distinct non-overlapping group of transcription factors (TFs) significantly upregulated in each phenotype: TFs upregulated in planktivores correspond to initial establishment of brain regions and overall architecture; TFs upregulated in piscivores correspond to the refinement of neurons and the formation of specific neuronal circuits. The planktivores independently of body size were characterized by interconnected activity of two TFs, fosab and junba. Gene set enrichment revealed extracellular matrix and collagen-related transcripts in piscivores from both years. A high activity of solute carrier (Slc) transporters was identified in the smaller-bodied piscivores. The neurotranscriptomics results reflected differences in body size and matched with ecological data and survival rates. The brain regulome indicated that body size differences translate into the specific gene activity of juvenile pikeperch.

Honey bees (Apis mellifera) provide important ecosystem services to both natural and human-managed environments, but are increasingly threatened by a variety of pathogens, the most common of which is deformed wing virus (DWV). DWV is known to replicate in the honey bee brain and has been documented as both improving and impairing olfactory learning and memory. We examined the transcriptomic response of the honey bee mushroom bodies - an area of the insect brain associated with higher cognitive functions - in bees with naturally occurring DWV infections, which varied in their ability to perform an associative learning task. RNA-sequencing analysis detected increased expression of genes involved in the immune response, including important antimicrobial peptides such as hymenoptaecin, apidaecin, and abaecin, and the downregulation of lysozyme, prophenoloxidase, and other genes associated with responses to a range of stressors. Additionally, gene ontology enrichment analysis revealed overrepresentation of key biological processes that form part of the immune response. We also noted significant differential expression of long non-coding RNAs (lncRNAs) presumed to be acting in a regulatory manner, and used these lncRNAs to construct gene regulatory networks. Strikingly, in contrast to previous studies on bees with artificially induced infections that have examined viral loads in the abdomen and non-specific areas of the brain, no correlation between DWV load in the mushroom bodies and cognitive function was noted. This highlights the complexity of host-pathogen interactions in honey bee neural tissues and the benefits of a spatially refined approach to brain transcriptomics in naturally occurring infections.

Enteroendocrine cells (EECs) are rare intestinal epithelial cells producing multiple hormones that regulate essential aspects of digestion and energy. EEC subtypes, their hormone repertoire and differentiation mechanisms from intestinal stem cells have been characterized in the adult intestine. Although EECs must be functional from birth because their absence leads to severe intestinal malabsorption in newborns, the processes that determine their subtype specification during development remain largely unknown. We used mouse embryos, human pluripotent stem cell-derived intestinal organoid models and single-cell transcriptomics to characterize EEC lineages and dynamics during development. Our findings demonstrate that in both mice and humans, the majority of EECs are specified during development through similar differentiation trajectories to those observed in the adult intestine. This suggests that EEC subtype specification occurs independently of fully organized crypt-villus structures and stimulation by diet or microbiota. However, the emergence of certain EEC subtypes depends on tissue maturation. Finally, our integrative approach infers lineage-specific regulators dynamically, identifying new candidates controlling EEC differentiation in the developing human gut.

Plant phytochemicals found in nectar impact bee learning and memory and plant pollination success. Especially for generalist pollinators, dietary changes that alter phytochemical consumption could be common sources of behavioral variation. For honey bee (Apis mellifera L.) foragers, a major potential change in phytochemical consumption occurs when individuals switch from collecting nectar from flowers to collecting honey from neighboring colonies, a phenomenon known as honey robbing. In this study we investigated whether phytochemicals dominant in honey compared to nectar act as a short-term trigger of robbing behaviors in honey bee, which include increased aggression. We fed forager honey bees sucrose diets containing different phytochemicals found in nectar and honey and tested aggression using a lab-based assay. We found no evidence that phytochemicals altered forager behavior. We also compared the microbiome composition for foragers fed different phytochemicals and again found no effects. Our results suggest that neither direct effects of neuroactive phytochemicals, nor indirect effects through the structure or function of the gut microbiome, trigger honey robbing behaviors.

First Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping researchers promote themselves alongside their papers. Julio Fierro Morales is first author on ' Differential PaxillinB dynamics at Dictyostelium cell-substrate adhesions', published in BiO. Julio conducted the research described in this article while a PhD student in Dr Minna Roh-Johnson's lab at the University of Utah, Salt Lake City, USA. He is now a postdoc in the lab of Dr Florentine Rutaganira at the Beckman Center, Stanford, USA, elucidating the evolution of molecular machinery such as cell-substrate adhesions using non-Metazoan model organisms.

The primary cilium, a microtubule-based membrane protrusion, is essential for eukaryotic development and health. Import and export of proteins in and out of the primary cilium relies on intraflagellar transport protein complexes (IFT) IFT-B and IFT-A, in conjunction with their respective motor proteins. Here, using mouse fibroblast cells, we investigated the function of IFT139 (Thm1, TTC21B) in Hedgehog signaling, cilia structure, and ciliary protein localization, as well as the effect of the P209L ciliopathy mutation on cell proliferation and Hedgehog signaling. In cells without IFT139, Ptch1 retains normal localization, Smo and Gli accumulate in the distal tips of cilia with or without pathway activation, while SuFu fails to accumulate in cilia upon pathway activation. We also found that Arl13b abnormally accumulates at the distal tips of cilia, but acetylated tubulin does not. Lastly, the ciliopathy mutation P209L impairs cell proliferation and Hedgehog transcriptional response, mimicking a loss of function in IFT139. Our work highlights the multifaceted roles IFT139 have on distinct ciliary proteins, and its importance in ciliopathies.

ADAMTS13 is a metalloprotease that cleaves the von Willebrand factor and prevents pathological thrombosis. Severe genetic deficiency of ADAMTS13 causes congenital thrombotic thrombocytopenic purpura, a life-threatening thrombotic microangiopathy. Increasing evidence suggests that ADAMTS13 contributes to physiological processes beyond hemostasis, including vascular development and tissue homeostasis, but these functions remain poorly understood. To address this gap, we generated a transparent, multitransgenic adamts13i5 zebrafish model and began investigating the developmental and disease-related roles of ADAMTS13 in vivo. The adamts13i5 mutants recapitulated hallmark features of congenital thrombotic thrombocytopenic purpura, including erythrocyte fragmentation and schistocyte formation in adults. In larvae, ADAMTS13 loss unveiled a prothrombotic response to vascular injury, a phenotype masked in patients by thrombocytopenia. Mechanistically, ADAMTS13 deficiency impaired developmental vascular patterning, suppressed vegfa expression, and reduced macrophage number, accompanied by diminished inflammatory and pro-angiogenic signaling. ADAMTS13 loss disrupted hematopoietic homeostasis in adulthood, with myeloid expansion and lymphoid depletion in the kidney marrow. These findings establish ADAMTS13 as a multifaceted regulator of thrombosis, vascular development, inflammation, and hematopoietic lineage specification. The adamts13i5 zebrafish provides a powerful vertebrate model for dissecting the mechanisms of thrombotic thrombocytopenic purpura pathogenesis and identifying therapeutic strategies extending beyond hemostasis.

Temperature is a critical factor that modulates cellular metabolism and stem cell regulation. Despite extensive studies, the influence of temperature on stem cell regulation via Notch signaling has been limited to studies relying on studies that involve indirect readouts to Notch activation. This study systematically analyzes the effects of temperature on the Notch signaling transcriptional response at the chromosomal, cellular, and tissue levels. Using complementary direct Notch readouts, we demonstrate that Notch activation remains largely unchanged across temperatures, suggesting the presence of temperature-compensatory mechanisms that maintain robust Notch activation. Notch transcriptional activity readouts, however, increased with temperature, indicating that elevated temperatures may enhance Notch transcriptional activity at the chromosomal level. These findings provide a comprehensive framework for understanding effects of temperature and offer new insights into the regulation of Notch signaling in stem cell biology.