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ELife Apr 2024We previously showed that SerpinE2 and the serine protease HtrA1 modulate fibroblast growth factor (FGF) signaling in germ layer specification and head-to-tail...
We previously showed that SerpinE2 and the serine protease HtrA1 modulate fibroblast growth factor (FGF) signaling in germ layer specification and head-to-tail development of embryos. Here, we present an extracellular proteolytic mechanism involving this serpin-protease system in the developing neural crest (NC). Knockdown of SerpinE2 by injected antisense morpholino oligonucleotides did not affect the specification of NC progenitors but instead inhibited the migration of NC cells, causing defects in dorsal fin, melanocyte, and craniofacial cartilage formation. Similarly, overexpression of the HtrA1 protease impaired NC cell migration and the formation of NC-derived structures. The phenotype of SerpinE2 knockdown was overcome by concomitant downregulation of HtrA1, indicating that SerpinE2 stimulates NC migration by inhibiting endogenous HtrA1 activity. SerpinE2 binds to HtrA1, and the HtrA1 protease triggers degradation of the cell surface proteoglycan Syndecan-4 (Sdc4). Microinjection of mRNA partially rescued NC migration defects induced by both HtrA1 upregulation and SerpinE2 downregulation. These epistatic experiments suggest a proteolytic pathway by a double inhibition mechanism. SerpinE2 ┤HtrA1 protease ┤Syndecan-4 → NC cell migration.
Topics: Animals; Cell Movement; Fibroblast Growth Factors; High-Temperature Requirement A Serine Peptidase 1; Neural Crest; Serpin E2; Signal Transduction; Xenopus laevis; Xenopus Proteins
PubMed: 38634469
DOI: 10.7554/eLife.91864 -
ZooKeys 2024We describe a new treefrog species from Lao Cai Province, northwestern Vietnam. The new species is assigned to the genus based on a combination of the following...
We describe a new treefrog species from Lao Cai Province, northwestern Vietnam. The new species is assigned to the genus based on a combination of the following morphological characters: (1) dorsum green, smooth; body size medium (SVL 30.1-32.2 in males); (2) fingers webbed; tips of digits expanded into large disks, bearing circum-marginal grooves; (3) absence of dermal folds along limbs; (4) absence of supracloacal fold and tarsal projection. The new species can be distinguished from its congeners by: (1) dorsal surface of the head and body green without spots; (2) axilla and groin cream with a black blotch; (3) ventral cream without spot; (4) chin creamy with grey marbling; anterior part of the thigh and ventral surface of tibia orange without spots; posterior parts of thigh orange with a large black blotch; (5) ventral side of webbing orange with some grey pattern (6) iris red-bronze, pupils black; (7) finger webbing formula I1¼-1¼II1-2III1-1IV, toe webbing formula I½-½II0-1½III¼-1¾IV1¾-½V. Phylogenetically, the new species is nested in the same subclade as , , and , with genetic distances ranging from 3.23% to 4.68%. The new species can be found in evergreen montane tropical forests at an elevation of about 1,883 m a.s.l. This new discovery brings the number of known genus species to 42 and the number of species reported from Vietnam to 10.
PubMed: 38628553
DOI: 10.3897/zookeys.1197.104851 -
Regulatory Toxicology and Pharmacology... May 2024The Xenopus Eleutheroembryonic Thyroid Assay (XETA) was recently published as an OECD Test Guideline for detecting chemicals acting on the thyroid axis. However, the... (Comparative Study)
Comparative Study
The Xenopus Eleutheroembryonic Thyroid Assay (XETA) was recently published as an OECD Test Guideline for detecting chemicals acting on the thyroid axis. However, the OECD validation did not cover all mechanisms that can potentially be detected by the XETA. This study was therefore initiated to investigate and consolidate the applicability domain of the XETA regarding the following mechanisms: thyroid hormone receptor (THR) agonism, sodium-iodide symporter (NIS) inhibition, thyroperoxidase (TPO) inhibition, deiodinase (DIO) inhibition, glucocorticoid receptor (GR) agonism, and uridine 5'-diphospho-glucuronosyltransferase (UDPGT) induction. In total, 22 chemicals identified as thyroid-active or -inactive in Amphibian Metamorphosis Assays (AMAs) were tested using the XETA OECD Test Guideline. The comparison showed that both assays are highly concordant in identifying chemicals with mechanisms of action related to THR agonism, DIO inhibition, and GR agonism. They also consistently identified the UDPGT inducers as thyroid inactive. NIS inhibition, investigated using sodium perchlorate, was not detected in the XETA. TPO inhibition requires further mechanistic investigations as the reference chemicals tested resulted in opposing response directions in the XETA and AMA. This study contributes refining the applicability domain of the XETA, thereby helping to clarify the conditions where it can be used as an ethical alternative to the AMA.
Topics: Animals; Thyroid Gland; Metamorphosis, Biological; Biological Assay; Endocrine Disruptors; Xenopus laevis; Receptors, Thyroid Hormone; Iodide Peroxidase; Symporters
PubMed: 38614220
DOI: 10.1016/j.yrtph.2024.105619 -
Molecules (Basel, Switzerland) Mar 2024The traditional Chinese medicine toad venom () has been extensively used to treat various diseases, including cancers, in China and other Southeast Asian countries. The...
The traditional Chinese medicine toad venom () has been extensively used to treat various diseases, including cancers, in China and other Southeast Asian countries. The major constituents of toad venom, e.g., bufadienolides and alkaloids, exhibit broad-spectrum pharmacological effects in cancers. Herein, two new bufadienolides ( and ), along with eleven known compounds (-) were successfully isolated from Schneider. Their structures were elucidated by extensive spectroscopic data and X-ray diffraction analysis. Furthermore, four lactam derivatives were synthesized through the transformation of bufadienolides lactones. The inhibitory effects of these compounds against human prostate cancer cell lines PC-3 and DU145 were evaluated. The outcomes indicated a notable trend, with a substantial subset displaying nanomolar range IC values against PC-3 and DU145 cells, underscoring their pronounced cytotoxicity. Moreover, a noteworthy distinction surfaces, wherein lactones consistently outperformed their lactam counterparts, further validating their heightened potency for the treatment of prostate cancer. This study contributes significant preclinical evidence substantiating the therapeutic viability of bufadienolides and toad venom as intervention strategies for prostate cancer.
Topics: Humans; Male; Animals; Prostatic Neoplasms; Antineoplastic Agents; Amphibian Venoms; Bufanolides; Bufonidae; Lactams; Lactones
PubMed: 38611850
DOI: 10.3390/molecules29071571 -
BMC Genomics Apr 2024Cold hardiness is fundamental for amphibians to survive during the extremely cold winter on the Qinghai-Tibet plateau. Exploring the gene regulation mechanism of...
BACKGROUND
Cold hardiness is fundamental for amphibians to survive during the extremely cold winter on the Qinghai-Tibet plateau. Exploring the gene regulation mechanism of freezing-tolerant Rana kukunoris could help us to understand how the frogs survive in winter.
RESULTS
Transcriptome of liver and muscle of R. kukunoris collected in hibernation and spring were assisted by single molecule real-time (SMRT) sequencing technology. A total of 10,062 unigenes of R. kukunoris were obtained, and 9,924 coding sequences (CDS) were successfully annotated. Our examination of the mRNA response to whole body freezing and recover in the frogs revealed key genes concerning underlying antifreeze proteins and cryoprotectants (glucose and urea). Functional pathway analyses revealed differential regulated pathways of ribosome, energy supply, and protein metabolism which displayed a freeze-induced response and damage recover. Genes related to energy supply in the muscle of winter frogs were up-regulated compared with the muscle of spring frogs. The liver of hibernating frogs maintained modest levels of protein synthesis in the winter. In contrast, the liver underwent intensive high levels of protein synthesis and lipid catabolism to produce substantial quantity of fresh proteins and energy in spring. Differences between hibernation and spring were smaller than that between tissues, yet the physiological traits of hibernation were nevertheless passed down to active state in spring.
CONCLUSIONS
Based on our comparative transcriptomic analyses, we revealed the likely adaptive mechanisms of R. kukunoris. Ultimately, our study expands genetic resources for the freezing-tolerant frogs.
Topics: Animals; Transcriptome; Cold-Shock Response; Tibet; Gene Expression Profiling; Ranidae; Anura
PubMed: 38609871
DOI: 10.1186/s12864-024-10248-8 -
The EMBO Journal May 2024The γ-tubulin ring complex (γ-TuRC) is a structural template for de novo microtubule assembly from α/β-tubulin units. The isolated vertebrate γ-TuRC assumes an...
The γ-tubulin ring complex (γ-TuRC) is a structural template for de novo microtubule assembly from α/β-tubulin units. The isolated vertebrate γ-TuRC assumes an asymmetric, open structure deviating from microtubule geometry, suggesting that γ-TuRC closure may underlie regulation of microtubule nucleation. Here, we isolate native γ-TuRC-capped microtubules from Xenopus laevis egg extract nucleated through the RanGTP-induced pathway for spindle assembly and determine their cryo-EM structure. Intriguingly, the microtubule minus end-bound γ-TuRC is only partially closed and consequently, the emanating microtubule is locally misaligned with the γ-TuRC and asymmetric. In the partially closed conformation of the γ-TuRC, the actin-containing lumenal bridge is locally destabilised, suggesting lumenal bridge modulation in microtubule nucleation. The microtubule-binding protein CAMSAP2 specifically binds the minus end of γ-TuRC-capped microtubules, indicating that the asymmetric minus end structure may underlie recruitment of microtubule-modulating factors for γ-TuRC release. Collectively, we reveal a surprisingly asymmetric microtubule minus end protofilament organisation diverging from the regular microtubule structure, with direct implications for the kinetics and regulation of nucleation and subsequent modulation of microtubules during spindle assembly.
Topics: Microtubules; Xenopus laevis; Animals; Microtubule-Associated Proteins; ran GTP-Binding Protein; Tubulin; Xenopus Proteins; Cryoelectron Microscopy; Spindle Apparatus
PubMed: 38600243
DOI: 10.1038/s44318-024-00087-4 -
Trends in Ecology & Evolution May 2024Despite the great diversity of parental care types found in amphibians, studies linking them to post-copulatory sexually selected traits are scarce, presumably due to a...
Despite the great diversity of parental care types found in amphibians, studies linking them to post-copulatory sexually selected traits are scarce, presumably due to a lack of data. Valencia-Aguilar et al. used fieldwork and museum collections to show that paternal care appears to trade-off with testes size in glass frogs.
Topics: Animals; Testis; Male; Paternal Behavior; Organ Size; Anura
PubMed: 38599935
DOI: 10.1016/j.tree.2024.04.001 -
Die Naturwissenschaften Apr 2024Frogs of the Allophrynidae are an enigmatic family from South America. To date, published information is lacking regarding this group's reproductive biology and larval...
Frogs of the Allophrynidae are an enigmatic family from South America. To date, published information is lacking regarding this group's reproductive biology and larval morphology. Here, we provide the first detailed description of the reproductive mode, developmental mode, and tadpole morphology for Allophryne ruthveni. We developed a captive breeding and rearing protocol for this species and then conducted a series of observations to describe aspects of its reproductive biology. In captivity, this species exhibits aquatic oviposition, where single eggs are laid ungrouped within a simple jelly capsule and are scattered free in the water column before sinking to develop on benthic substrates. We did not observe parental care nor any parental interactions with eggs post-fertilization. Tadpoles are characterized by an oval body, anteroventral oral disc, a labial tooth row formula of 2(2)/3, and a dextral vent tube. The buccopharyngeal cavity is marked by the presence of two pairs of infralabial papilla and four lingual papillae. Cranial morphology is characterized by the presence of the commissura quadratoorbital. This species possesses an additional slip of the m. rectus cervicis and of the m. levator arcuum branchialium III. We discuss our results in comparison with glassfrogs (Centrolenidae).
Topics: Female; Animals; Anura; Reproduction; Oviposition; Larva; Skull
PubMed: 38598027
DOI: 10.1007/s00114-024-01910-y -
The International Journal of... 2024In vertebrate development, ectoderm is specified into neural plate (NP), neural plate border (NPB), and epidermis. Although such patterning is thought to be achieved by...
In vertebrate development, ectoderm is specified into neural plate (NP), neural plate border (NPB), and epidermis. Although such patterning is thought to be achieved by molecular concentration gradients, it has been revealed, mainly by analysis, that mechanical force can regulate cell specification. During patterning, cells deform and migrate, and this applies force to surrounding tissues, shaping the embryo. However, the role of mechanical force for cell specification is largely unknown. In this study, with an aspiration assay and atomic force microscopy, we have demonstrated that tension on ectodermal cells decreases laterally from the midline in early neurula. Ectopically applied force laterally expanded the neural crest (NC) region, a derivative of the NPB, whereas force relaxation suppressed it. Furthermore, force application activated both the FGF and Wnt pathways, which are required for NC formation during neuroectodermal patterning. Taken together, mechanical force is necessary for NC formation in order to regulate signaling pathways. Furthermore, molecular signals specify the NP and generate force on neighboring tissue, the NPB, with its closure. This force activates signals, possibly determining the appropriate width of a narrow tissue, the NC.
Topics: Animals; Neural Crest; Xenopus laevis; Xenopus Proteins; Ectoderm; Wnt Signaling Pathway; Gene Expression Regulation, Developmental
PubMed: 38591691
DOI: 10.1387/ijdb.230273tm -
The Journal of Biological Chemistry May 2024We describe molecular-level functional changes in the α4β2 nicotinic acetylcholine receptor by a leucine residue insertion in the M2 transmembrane domain of the α4...
We describe molecular-level functional changes in the α4β2 nicotinic acetylcholine receptor by a leucine residue insertion in the M2 transmembrane domain of the α4 subunit associated with sleep-related hyperkinetic epilepsy. Measurements of agonist-elicited single-channel currents reveal the primary effect is to stabilize the open channel state, while the secondary effect is to promote reopening of the channel. These dual effects prolong the durations of bursts of channel openings equally for the two major stoichiometric forms of the receptor, (α4)(β2) and (α4)(β2), indicating the functional impact is independent of mutant copy number per receptor. Altering the location of the residue insertion within M2 shows that functionally pivotal structures are confined to a half turn of the M2 α-helix. Residue substitutions within M2 and surrounding α-helices reveal that both intrasubunit and intersubunit interactions mediate the increase in burst duration. These interactions impacting burst duration depend linearly on the size and hydrophobicity of the substituting residue. Together, the results reveal a novel structural region of the α4β2 nicotinic acetylcholine receptor in which interhelical interactions tune the stability of the open channel state.
Topics: Animals; Humans; HEK293 Cells; Ion Channel Gating; Mutagenesis, Insertional; Protein Domains; Receptors, Nicotinic; Xenopus laevis
PubMed: 38583864
DOI: 10.1016/j.jbc.2024.107266