SH2 domain protein E and ABL signaling regulate blood vessel size.

Blood vessels in different vascular beds vary in size, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood. Src homology 2 domain containing E (She) protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vessel size in zebrafish embryos and human endothelial cell culture. Zebrafish she mutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow, eventually leading to the DA collapse. Vascular endothelial specific overexpression of she resulted in a reduced diameter of the DA, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated the she mutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA size in she mutants correlated with an increased endothelial expression of claudin 5a (cldn5a), which encodes a protein enriched in tight junctions. Inhibition of cldn5a expression partially rescued the enlarged DA in she mutants, suggesting that She regulates DA size, in part, by promoting cldn5a expression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates vessel and lumen size during vascular tubulogenesis.

Requirement of a novel gene, drish, in the zebrafish retinal ganglion cell and primary motor axon development.

BACKGROUND: During neurogenesis, growing axons must navigate through the complex extracellular environment and make correct synaptic connections for the proper functioning of neural circuits. The mechanisms underlying the formation of functional neural networks are still only partially understood. RESULTS: Here we analyzed the role of a novel gene si:ch73-364h19.1/drish in the neural and vascular development of zebrafish embryos. We show that drish mRNA is expressed broadly and dynamically in multiple cell types including neural, glial, retinal progenitor and vascular endothelial cells throughout the early stages of embryonic development. To study Drish function during embryogenesis, we generated drish genetic mutant using CRISPR/Cas9 genome editing. drish loss-of-function mutant larvae displayed defects in early retinal ganglion cell, optic nerve and the retinal inner nuclear layer formation, as well as ectopic motor axon branching. In addition, drish mutant adults exhibited deficient retinal outer nuclear layer and showed defective light response and locomotory behavior. However, vascular patterning and blood circulation were not significantly affected. CONCLUSIONS: Together, these data demonstrate important roles of zebrafish drish in the retinal ganglion cell, optic nerve and interneuron development and in spinal motor axon branching.

Endocardium gives rise to blood cells in zebrafish embryos.

Previous studies have suggested that the endocardium contributes to hematopoiesis in murine embryos, although definitive evidence to demonstrate the hematopoietic potential of the endocardium is still missing. Here, we use a zebrafish embryonic model to test the emergence of hematopoietic progenitors from the endocardium. By using a combination of expression analysis, time-lapse imaging, and lineage-tracing approaches, we demonstrate that myeloid cells emerge from the endocardium in zebrafish embryos. Inhibition of Etv2/Etsrp or Scl/Tal1, two known master regulators of hematopoiesis and vasculogenesis, does not affect the emergence of endocardial-derived myeloid cells, while inhibition of Hedgehog signaling results in their reduction. Single-cell RNA sequencing analysis followed by experimental validation suggests that the endocardium is the major source of neutrophilic granulocytes. These findings will promote our understanding of alternative mechanisms involved in hematopoiesis, which are likely to be conserved between zebrafish and mammalian embryos.

Thyroid Malignancy among Fine Needle Aspiration Cytology of Thyroid Lesions in a Tertiary Care Centre.

Introduction: The most prevalent endocrine cancer in the world is thyroid cancer, and its incidence is on the rise. The distinction between benign and malignant thyroid nodules must be made, which is why fine needle aspiration cytology of thyroid lesion is necessary and required. This study aimed to find out the prevalence of thyroid malignancy among fine needle aspiration cytology of thyroid lesions in a tertiary care centre. Methods: A descriptive cross-sectional study was conducted among fine needle aspiration cytology of thyroid lesions in a tertiary care centre after obtaining ethical approval from the Institutional Review Committee. Data from 13 April 2020 to 13 April 2023 was collected between 19 May 2023 to 19 June 2023. All the patients with complete hospital record data were included in this study. However, repetitive fine needle aspiration cytology of thyroid lesion were excluded from the study. Fine needle aspiration cytology diagnoses were categorized in this study as per the Bethesda system for reporting thyroid cytopathology. The point estimate was calculated at a 95% Confidence Interval. Results: Among 398 fine needle aspiration cytology of thyroid lesions, thyroid malignancy was seen in 12 (3.02%) (1.34-4.70, 95% Confidence Interval) patients. Conclusions: The prevalence of thyroid malignancy was found to be lower than other studies done in similar settings. Keywords: cytology; malignancy; prevalence; thyroid.