Cell and Tissue Research最新文献

Taste buds are maintained by continuous cell renewal, receiving a steady influx of postmitotic cells from the surrounding epithelial region. Within taste buds, Type I, II, and III cells continuously differentiate from Type IV postmitotic precursor cells and are removed via apoptosis. These processes are likely governed by various transcription factors. Among the transcription factors expressed in taste buds, Prox1, a homeobox transcription factor, is the only factor expressed in all taste bud cells including precursor cells. However, its role in taste buds remains unclear. Here, we investigate the function of Prox1 in taste bud cell turnover using conditional knockout (cKO) mice. In Prox1 cKO mice, all Type I, II, and III cells were significantly reduced, resulting in approximately half the total cell number per taste bud compared to wild-type mice, while Type IV cell numbers remained comparable. Apoptosis of taste bud cells nearly doubled, leading to a shortened lifespan of taste bud cells. EdU pulse-labeling experiments revealed a biphasic decline in EdU(+) taste bud cells in Prox1 cKO mice, indicating that Prox1 knockout increases the fraction of cells that die shortly after differentiating into taste bud cells. The surviving cells still exhibited a shorter lifespan than that of wild-type mice. We also observed previously unreported structural alterations within taste buds caused by enhanced apoptosis using whole-mount analysis. These results demonstrate that Prox1 contributes to the maintenance of taste bud structure by regulating the lifespan of taste bud cells, highlighting its essential role in taste bud homeostasis.

Rab24 is an unusual member of the Rab family of small GTPases, implicated in autophagy, endocytosis and cell division. In order to elucidate possible organ and age-specific roles of Rab24, we investigated tissue-specific levels of Rab24 in mice by western blotting and immunohistochemistry from postnatal day one to 9 months of age. In adult mice, the highest protein levels were found in the brain followed by the kidney, whereas lower levels were detected in the pancreas, spleen, liver, lung, heart, and skeletal muscle. Dynamic changes in Rab24 levels were observed during early postnatal development, with a sharp increase in the brain at postnatal day 14, after which the level remained high into adulthood. In the heart, skeletal muscle, pancreas and liver, higher Rab24 levels were observed during the first two postnatal weeks, after which the levels dropped and stayed low until adulthood. The age-dependent changes suggest age- and organ-specific regulation of Rab24 protein levels and possible organ-specific roles for Rab24 in development and maturation. Immunohistochemistry of the brain revealed that Rab24 was mostly present in neuronal cells in 1-month-old and older mice. Also, epithelial cells in several tissues showed high Rab24 levels. These results suggest possible roles for Rab24 in neuronal and epithelial maintenance. We further analysed immunohistochemical staining for RAB24 in human cancers and normal tissues. RAB24 staining in cancers of the breast and skin was higher than in the corresponding normal tissues, while it was reduced in cancers of the digestive system and the urinary tract. We also observed elevated RAB24 staining in medulloblastoma and neuroblastoma, two paediatric cancers of neuronal origin. In pancreatic neuroendocrine tumours that originate from islet cells, RAB24 levels were lower than in normal pancreatic islet cells. Collectively, our findings provide a comprehensive overview of RAB24 protein levels across mouse tissues and a wide spectrum of human cancers. The observed differences in RAB24 levels between cancer types and between malignant and normal tissues, suggest that RAB24 may serve as a potential diagnostic or differentiation marker in specific tumour types.

Pannexin-1 (Panx1) is a large-pore membrane channel protein implicated in diverse physiological and pathological processes, yet its presence in extracellular vesicles has not been fully characterized. In this study, we investigated small extracellular vesicles derived from bovine milk to determine whether they contain Panx1. Using multiple complementary approaches, we show that Panx1 is present in a distinct subpopulation of milk-derived vesicles. Panx1 immunoreactivity was detected by Western blotting with antibodies targeting both the C-terminal and extracellular loop regions, and single-molecule localization microscopy revealed that a subpopulation of CD9-positive mEVs expresses Panx1. Consistently, flow cytometry-based analysis indicated that approximately half of the vesicle population was Panx1 positive. Together, these findings provide the first validated evidence that Panx1 is incorporated into bovine milk-derived small extracellular vesicles, expanding the repertoire of membrane channel proteins associated with extracellular vesicles and establishing a foundation for future studies on the functional role of Panx1 in vesicle biology and vesicle-mediated signaling.

Cisplatin is a first-line chemotherapeutic agent for various tumors; however, its clinical utility is substantially limited by the risk of cisplatin-induced acute kidney injury (AKI). Since inhibition of ferroptosis effectively mitigates cisplatin toxicity, we aimed to expand the therapeutic window of cisplatin by identifying potent ferroptosis inhibitors. High-throughput quantitative cell imaging-based screening of an FDA-approved drug library identified phenothiazine (PTZ) as a promising ferroptosis inhibitor. We further validated the ferroptosis-inhibitory activity of PTZ under both GPX4 inhibition and cystine deprivation conditions. Notably, PTZ administration markedly attenuated cisplatin-induced AKI and dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD) in mouse models. These findings indicate that PTZ holds clinical potential for reducing cisplatin-associated nephrotoxicity, thereby broadening the therapeutic applicability of cisplatin, as well as for treating IBD. Given its robust anti-ferroptosis effects, PTZ may also provide therapeutic benefits in other ferroptosis-related pathologies. Collectively, this study identifies PTZ as a promising lead compound for the development of ferroptosis-targeted therapeutics.

Heart disease is the leading cause of death globally. Although modern interventions have dramatically reduced the morbidity and mortality of heart disease, the lack of knowledge of key underlying mechanisms has limited the development of effective therapeutics. Pannexins encompass a group of three transmembrane channel-forming proteins best known for their role in purinergic signaling through the release of ATP. Pannexins, particularly pannexin 1 (Panx1), are expressed in multiple cell types throughout the heart and play a role in blood vessel regulation, immune cell recruitment and activation, and the response to ischemic injury. In this review, we analyze publicly available sequencing data to investigate the expression of pannexin proteins in human and mouse hearts at both tissue and single-cell levels. We provide a detailed review of the literature surrounding cardiac pannexin function in the context of both ischemic and non-ischemic heart disease. We then discuss the clinical use of drugs now known to target pannexin channels as a primer for the therapeutic potential of pannexins in cardiac dysfunction. Finally, we discuss the largest gaps in the current literature to guide future research.

Evolutionary pressure on the gastrointestinal (GI) tract of teleost fish differs substantially from those of terrestrial animals. The intestine is a pivotal organ in teleost, for maintaining osmotic balance against the surrounding aquatic environment; primarily through its role in water absorption. Intestinal sensory and motor functions of vertebrates are largely mediated by the enteric nervous system (ENS) embedded within the gut wall. Although the ENS has been described in several teleost species, the group comprised of more than 25,000 species displays remarkable ecological, anatomical, and physiological diversity. As such, species that display distinct adaptations, i.e., euryhalinity, may provide valuable comparative insights. Here we show the structure of the ENS within the intestine of barramundi (Lates calcarifer), a catadromous perch species with a unique life history and growing commercial relevance. Immunohistochemical labelling identified enteric neurons synthesising nitric oxide synthase (NOS) and calcitonin-gene-related peptide (CGRP), both of which were typically uniaxonal with smooth cell bodies. Qualitatively, these neuronal populations formed a weakly arranged enteric plexus, analogous to the myenteric plexus found in terrestrial animals. Quantitatively, the proportion of NOS immunoreactive neurons decreased along the rostro-caudal axis of the intestine without accompanying changes to the overall neuronal density. Video imaging of intestinal wall movements ex vivo identified multiple recurrent motility patterns which were hexamethonium-sensitive, suggesting regulation by nicotinic synaptic transmission within enteric pathways. Together, these findings show that enteric neurons are present in the barramundi intestine but form a comparatively less defined plexus than in higher terrestrial vertebrates. These enteric neurons are involved in the regulation of intestinal motility via nicotinic transmission.

Meckel's cartilage is a transient yet essential structure in the development of the mammalian mandible, with its midsegment undergoing distinct degradation and potentially contributing to bone formation. However, the mechanisms regulating its fate remain unclear. This study aimed to investigate the spatiotemporal changes and potential osteogenic function of the midsegment of Meckel's cartilage during mouse mandibular development. Using C57BL/6 J mice and a tamoxifen-inducible cartilage-specific lineage tracing model, we conducted morphological staining (Alcian Blue, Safranin O, Masson's trichrome) and immunofluorescence analyses targeting key transcription factors (Sox9, Runx2, Osterix) and vascular marker CD31 from embryonic day 12.5 to postnatal day 0. The anterior portion of the midsegment displayed endochondral-like ossification, marked by chondrocyte hypertrophy, matrix remodeling, and subsequent osteogenic invasion. A shift from cell proliferation to differentiation was noted as Ki67-positive cells decreased by embryonic day 14.5. Sequential expression of Sox9, Runx2, and Osterix was observed along the chondrocyte maturation axis, with peripheral localization of Osterix-expressing cells in remodeling zones. Endothelial cells expressing CD31 were closely associated with osteoprogenitor cells co-expressing Runx2 or Osterix, particularly on the incisor-facing side, indicating a spatial relationship between vascular structures and osteogenic differentiation. These findings demonstrate that the midsegment of Meckel's cartilage undergoes an endochondral-like ossification process similar to long bones, involving a Sox9 → Runx2 → Osterix transcriptional cascade and vascular invasion. Thus, our study provides novel evidence of the dynamic ossification of Meckel's cartilage midsegment, clarifying its role in mandibular development and contributing to the long-standing debate on its evolutionary and developmental significance.

For the first time, the morphological properties of organelles with screening pigment in the supporting cells of the non-optic part and the peripheral and central region of the optic part of the retina of the camera-like eye of the gastropod Helix pomatia were studied using light and transmission electron microscopy: way of arranging; shape; location; way of packaging; structure. A comparative visual assessment of the number of organelles with a screening pigment having a different way of arranging and the number of organelles with a screening pigment having a different shape for each way of arranging was performed, and the size of organelles with a screening pigment in the supporting cells of the non-optic part and the peripheral and central region of the optic part of the retina of the camera-like eye of H. pomatia was measured. It was shown that organelles with screening pigment in the supporting cells of the non-optic part and the peripheral and central region of the optic part of the retina of the camera-like eye of H. pomatia have more similarities than differences in morphological properties, number, and size.

Pannexin (Panx)-1-mediated ATP release has been associated with a broad range of pathological conditions. Conversely, the use of Panx1-inhibitors has shown promising results in the medication of diseases, such as neuroinflammation, melanoma and epilepsy. In addition, Panx1-inhibitors are an indispensable tool for the elucidation of both structure and physiology of Panx1. Over the past years, numerous applications of Panx1-inhibitors have led to new insights into Panx1 influences in health and disease. The major drawback of conventional Panx1-inhibitors, however, is the lack of selectivity resulting in undesired side effects. Nevertheless, these inhibitors are useful resources for drug discovery and lead optimisation approaches have therefore found their way into Panx1 research. Newly developed inhibitors show both high efficacy and selectivity. The combination of drug development and molecular dynamics simulations is a powerful tool to further elucidate both structure and gating mechanisms of Panx1.

Mammalian thyroid peroxidase (TPO), a thyroid-specific peroxidase involved in thyroid hormone synthesis, has a characteristic hydrophobic region in the C-terminus (HRC) that anchors peroxidase to the apical membrane of epithelial follicle cells. Protochordates (lancelets and ascidians) have TPO-like (TPOL) peroxidases with or without HRC, and their expression has been reported in the endostyle. We herein investigated the molecular structures of TPOL in protochordates and TPO relatives in vertebrates, including eosinophil peroxidase, myeloperoxidase, and lactoperoxidase, with a focus on the existence of HRC. Our molecular phylogenetic analysis implied that ancestral chordates evolved HRC-containing peroxidases, and mammalian TPO maintained HRC despite many TPO relatives losing it. Gene expression profiles revealed by in situ hybridization and an RNA-seq analysis showed that transcripts of TPOL genes in protochordates were distributed to pharyngeal epithelia in addition to the endostyle. Furthermore, disturbances in TPO activity by a thiourea treatment and gene knockdown experiments resulted in a deficiency of pharyngeal mucus-sheets. Collectively, these results suggest that HRC-containing TPOL was originally involved in pharyngeal mucus-sheet formation for suspension feeding in ancestral chordates, and HRC may have evolved to maintain peroxidase anchoring to the apical surface of pharyngeal epithelia.