Biology subjects

Chung, B.-c.

Publications and source records attributed to Chung, B.-c..

3 recordsLinked to original sources

bioRxiv2024

Zebrafish Foxl2l functions in proliferating germ cells for female meiotic entry

AbstractZebrafish sex differentiation is a complicated process and the detailed mechanism has not been fully understood. Here we characterized a transcription factor, Foxl2l, that participates in female oogenesis. We show that it is expressed specifically in proliferating germ cells in juvenile gonads and mature ovaries. We have used CRISPR-Cas9 to generate zebrafish deficient in foxl2l expression. Zebrafish with foxl2l-/- are all males, and this female-to-male sex reversal cannot be reversed by tp53 mutation, indicating this sex reversal is unrelated to cell death. We have generated transgenic fish expressing GFP under the control of foxl2l promoter to track the development of foxl2l+-germ cells, which failed to enter meiosis and were accumulated as cystic cells. Our RNA-seq analysis also showed the reduced expression of genes in meiosis and oogenesis among other affected pathways. All together, we show that zebrafish Foxl2l is a nuclear factor controlling the expression of meiotic and oogenic genes, and its deficiency leads to defective meiotic entry and the accumulation of premeiotic germ cells. HighlightsO_LIZebrafish foxl2l is expressed only in proliferating germ cells in juvenile gonads and mature ovaries. C_LIO_LIFoxl2l is a nuclear factor that promotes expression of genes involved in meiosis and oogenesis. C_LIO_LIZebrafish depleted of foxl2l lack meiotic oocytes in juveniles and become all males in adults. C_LIO_LIMutation of foxl2l leads to the accumulation of premeiotic germ cells. C_LI

developmental biology↗

bioRxiv2024

Zebrafish Foxl2l suppresses stemness and directs feminization of germline progenitors

Zebrafish is an important organism for genetic studies, but its germ cell types and the mechanism of sex differentiation remain elusive. Here, we conducted a single-cell transcriptomic profiling and charted a developmental trajectory going from germline stem cells, through early, committed, and late progenitors, to pre-meiotic and meiotic cells. A transcription factor, Foxl2l, is expressed in the progenitors committed to the ovary fate. CRISPR-Cas9-mediated mutation of foxl2l produced 100% male fish with normal fertility. Another single-cell profiling of foxl2l-/- germ cells reveals the arrest of early progenitors. Concomitantly the expression of nanos2 (stem cell marker) and id1 (transcription repressor in stem cells) was elevated together with an increase of nanos2+ germ cell in foxl2l mutants, indicating the reversion to the stem cell state. Thus, we have identified developmental stages of germ cells in juvenile zebrafish and demonstrated that Foxl2l drives zebrafish germ cell progenitors toward feminization and prevents them from reverting back to the stem cell state.

developmental biology↗

bioRxiv2022

Pregnenolone reorganizes cytoskeleton to promote neuron development via CLIP1

Pregnenolone (P5) is a neurosteroid produced in the brain. It improves cognitive function and protects against cannabis intoxication as well as spinal cord injury. P5 activates CLIP1, which helps microtubule polymerization at its growing end; however, the significance of P5 activation of CLIP1 in the brain is still unknown. Here we examined the roles of P5 in cultured neurons and in zebrafish cerebellum. We show that P5 promotes neurite outgrowth and facilitates axon development of cultured cerebellar granule neurons. P5 also changes the morphology of axon growth cone and promotes dynamic microtubule invasion into the distal part of filopodia at the growth cone. We have used CRISPR to disrupt clip1a in zebrafish, disrupting the ability of P5 to change microtubule dynamics and growth cone morphology, as well as to reorganize cytoskeleton. In vivo, P5 accelerated cerebellum development in WT but not clip1a mutant zebrafish, and expression of exogenous CLIP1 in clip1a mutant promoted cerebellum development in response to P5. Thus, we have delineated the pathway by which P5 promotes cerebellum development by activating CLIP1 to promote microtubule dynamics leading to increased microtubule penetration into the growth cone and accelerated neurite outgrowth. This study reveals the mechanism by which P5 and CLIP1 function to promote neural development. Significance Statement1. We have elucidated the mechanism of pregnenolone (P5) actionP5 enhances brain functions, but its mode of action was unclear. Here we show that P5 activates CLIP1 to promote microtubule dynamics at the growth cone and to accelerate neural development. 2. We have generated a zebrafish model of CLIP1 deficiencyCLIP1 deficiency causes intellectual disability and defective neural development. Our zebrafish model can be used to study mechanisms related to this disease and other microtubule defects. 3. We point to therapeutic intervention of neurological diseases using P5P5 is beneficial to the brain. We elucidate the mechanism of P5 action, thus accelerate the development of therapeutics using P5 and its derivatives.

neuroscience↗