A review on Tsukushi: mammalian development, disorders, and therapy

Thymus-forming potential of the second pharyngeal pouch and its regulation by local mesenchyme in avian embryos

The thymus derives from the endoderm of pharyngeal pouches (PPs). The number and location of PPs with thymus-forming potential differ among jawed vertebrates, and ectopic thymus locations in mice and humans suggest a broader thymus-forming potential in PP endoderm than previously ascribed. We used the quail-chick chimera system to test if non-canonical pouches could form a thymus and examined the role of pharyngeal arch (PA) mesenchyme in this process. After testing several tissue associations, we identified thymus-forming potential in both non-canonical second PP and canonical third/fourth PP endoderm. We found the 3/4PA and the ventral region of 2PA mesenchyme to be capable of positively regulating this potential, while the dorsal region of 2PA exerts an inhibitory effect. Transcriptomic analysis revealed a shared genetic program associated with thymic potential in PP endoderm and uncovered distinct signaling pathways mediating cellular interactions between PP endoderm and PA mesenchyme, which modulate this thymic potential.

Hepatokines: unveiling the molecular and cellular mechanisms connecting hepatic tissue to insulin resistance and inflammation

Insulin resistance arising from Non-Alcoholic Fatty Liver Disease (NAFLD) stands as a prevalent global ailment, a manifestation within societies stemming from individuals' suboptimal dietary habits and lifestyles. This form of insulin resistance emerges as a pivotal factor in the development of type 2 diabetes mellitus (T2DM). Emerging evidence underscores the significant role of hepatokines, as hepatic-secreted hormone-like entities, in the genesis of insulin resistance and eventual onset of type 2 diabetes. Hepatokines exert influence over extrahepatic metabolism regulation. Their principal functions encompass impacting adipocytes, pancreatic cells, muscles, and the brain, thereby playing a crucial role in shaping body metabolism through signaling to target tissues. This review explores the most important hepatokines, each with distinct influences. Our review shows that Fetuin-A promotes lipid-induced insulin resistance by acting as an endogenous ligand for Toll-like receptor 4 (TLR-4). FGF21 reduces inflammation in diabetes by blocking the nuclear translocation of nuclear factor-κB (NF-κB) in adipocytes and adipose tissue, while also improving glucose metabolism. ANGPTL6 enhances AMPK and insulin signaling in muscle, and suppresses gluconeogenesis. Follistatin can influence insulin resistance and inflammation by interacting with members of the TGF-β family. Adropin show a positive correlation with phosphoenolpyruvate carboxykinase 1 (PCK1), a key regulator of gluconeogenesis. This article delves into hepatokines' impact on NAFLD, inflammation, and T2DM, with a specific focus on insulin resistance. The aim is to comprehend the influence of these recently identified hormones on disease development and their underlying physiological and pathological mechanisms.

Characteristics of the Follicular Fluid Extracellular Vesicle Molecular Profile in Women in Different Age Groups in ART Programs

The aim of this study was to investigate the molecular composition of follicular fluid (FF) extracellular vesicles (EVs) in women of different reproductive ages and its possible relationship to sperm fertilizing ability. FF EVs were obtained by differential centrifugation. The concentration and size distribution of FF EVs were analyzed by nanoparticle tracking analysis. The lipidome and proteome were analyzed by liquid chromatography-mass spectrometry. The isolated FF EVs had a variety of shapes and sizes; their concentration and size distribution did not differ significantly between the age groups. In women younger than 35 years, the concentration of vesicular progesterone was 6.6 times higher than in women older than 35 years, and the total levels of the main lipid classes were increased in younger women. A proteomic analysis revealed that not only FF EV-specific proteins, but also proteins involved in sperm activation were present. New data were obtained on the composition of FF EVs, confirming their importance as molecular indicators of age-related changes in the female reproductive system. In addition, these results shed light on the possible interaction between the FF EVs of women in different age groups and male germ cells. Therefore, studying the transcriptomic and metabolomic profile of FF EVs may be a crucial approach to evaluate the efficacy of ART.

ASPORIN: A root of the matter in tumors and their host environment

Asporin (ASPN) has been identified as one of the members of the class I small leucine-rich proteoglycans (SLRPs) family in the extracellular matrix (ECM). It is involved in classic ensigns of cancers such as self-dependent growth, resistance to growth inhibitors, restricting apoptosis, cancer metastasis, and bone-related disorders. ASPN is different from other members of SLRPs, such as decorin (DCN) and biglycan (BGN), in a way that it contains a distinctive length of aspartate (D) residues in the amino (N) -terminal region. These D-repeats residues possess germline polymorphisms and are identified to be linked with cancer progression and osteoarthritis (OA). The polyaspartate stretch in the N-terminal region of the protein and its resemblance to DCN are the reasons it is called asporin. In this review, we comprehensively summarized and updated the dual role of ASPN in various malignancies, its structure in mice and humans, variants, mutations, cancer-associated signalings and functions, the relationship between ASPN and cancer-epithelial, stromal fibroblast crosstalk, immune cells and immunosuppression in cancer and other diseases. In cancer and other bone-related diseases, ASPN is identified to be regulating various signaling pathways such as TGFβ, Wnt/β-catenin, notch, hedgehog, EGFR, HER2, and CD44-mediated Rac1. These pathways promote cancer cell invasion, proliferation, and migration by mediating the epithelial-to-mesenchymal transition (EMT) process. Finally, we discussed mouse models mimicking ASPN in vivo function in cancers and the probability of therapeutic targeting of ASPN in cancer cells, fibrosis, and other bone-related diseases.

The pathological potential of ependymal cells in mild traumatic brain injury

Mild traumatic brain injury (mTBI) is a common neurological condition affecting millions of individuals worldwide. Although the pathology of mTBI is not fully understood, ependymal cells present a promising approach for studying the pathogenesis of mTBI. Previous studies have revealed that DNA damage in the form of γH2AX accumulates in ependymal cells following mTBI, with evidence of widespread cellular senescence in the brain. Ependymal ciliary dysfunction has also been observed, leading to altered cerebrospinal fluid homeostasis. Even though ependymal cells have not been extensively studied in the context of mTBI, these observations reflect the pathological potential of ependymal cells that may underlie the neuropathological and clinical presentations of mTBI. This mini review explores the molecular and structural alterations that have been reported in ependymal cells following mTBI, as well as the potential pathological mechanisms mediated by ependymal cells that may contribute to overall dysfunction of the brain post-mTBI. Specifically, we address the topics of DNA damage-induced cellular senescence, dysregulation of cerebrospinal fluid homeostasis, and the consequences of impaired ependymal cell barriers. Moreover, we highlight potential ependymal cell-based therapies for the treatment of mTBI, with a focus on neurogenesis, ependymal cell repair, and modulation of senescence signaling pathways. Further insight and research in this field will help to establish the role of ependymal cells in the pathogenesis of mTBI and may lead to improved treatments that leverage ependymal cells to target the origins of mTBI pathology.

Tsukushi proteoglycan maintains RNA splicing and developmental signaling network in GFAP-expressing subventricular zone neural stem/progenitor cells

Tsukushi (TSK) proteoglycan dysfunction leads to hydrocephalus, a condition defined by excessive fluid collection in the ventricles and lateral ventricular enlargement. TSK injections into the LV at birth are effective at rescuing the lateral ventricle (LV). TSK regulates the activation of the Wnt signaling to facilitate the proper expansion of the LV and maintain the fate of the neural stem cell lineage. However, the molecular mechanism by which TSK acts on neural stem/progenitor cells (NSCs) during LV development is unknown. We demonstrated that TSK is crucial for the splicing and development-associated gene regulation of GFAP-expressing subventricular zone (SVZ) NSCs. We isolated GFAP-expressing NSCs from the SVZ of wild-type (GFAPGFP/+/TSK+/+) and TSK knock-out (GFAPGFP/+/TSK−/−) mice on postnatal day 3 and compared their transcriptome and splicing profiles. TSK deficiency in NSCs resulted in genome-wide missplicing (alteration in exon usage) and transcriptional dysregulation affecting the post-transcriptional regulatory processes (including splicing, cell cycle, and circadian rhythm) and developmental signaling networks specific to the cell (including Wnt, Sonic Hedgehog, and mTOR signaling). Furthermore, TSK deficiency prominently affected the splicing of genes encoding RNA and DNA binding proteins in the nervous SVZ and non-nervous muscle tissues. These results suggested that TSK is involved in the maintenance of correct splicing and gene regulation in GFAP-expressing NSCs, thereby protecting cell fate and LV development. Hence, our study provides a critical insight on hydrocephalus development.

Assessing the Role of Ependymal and Vascular Cells as Sources of Extracellular Cues Regulating the Mouse Ventricular-Subventricular Zone Neurogenic Niche

Neurogenesis persists in selected regions of the adult mouse brain; among them, the ventricular-subventricular zone (V-SVZ) of the lateral ventricles represents a major experimental paradigm due to its conspicuous neurogenic output. Postnatal V-SVZ neurogenesis is maintained by a resident population of neural stem cells (NSCs). Although V-SVZ NSCs are largely quiescent, they can be activated to enter the cell cycle, self-renew and generate progeny that gives rise to olfactory bulb interneurons. These adult-born neurons integrate into existing circuits to modify cognitive functions in response to external stimuli, but cells shed by V-SVZ NSCs can also reach injured brain regions, suggesting a latent regenerative potential. The V-SVZ is endowed with a specialized microenvironment, which is essential to maintain the proliferative and neurogenic potential of NSCs, and to preserve the NSC pool from exhaustion by finely tuning their quiescent and active states. Intercellular communication is paramount to the stem cell niche properties of the V-SVZ, and several extracellular signals acting in the niche milieu have been identified. An important part of these signals comes from non-neural cell types, such as local vascular cells, ependymal and glial cells. Understanding the crosstalk between NSCs and other niche components may aid therapeutic approaches for neuropathological conditions, since neurodevelopmental disorders, age-related cognitive decline and neurodegenerative diseases have been associated with dysfunctional neurogenic niches. Here, we review recent advances in the study of the complex interactions between V-SVZ NSCs and their cellular niche. We focus on the extracellular cues produced by ependymal and vascular cells that regulate NSC behavior in the mouse postnatal V-SVZ, and discuss the potential implication of these molecular signals in pathological conditions.