In Caenorhabditis elegans, the formation of a functional vulval–uterine connection is essential for successful egg-laying. This connection relies on the precise specification of ventral uterine (VU) granddaughters into p cell fates, which subsequently give rise to the uterine seam cell (utse) and uv1 cells. Our study reveals that histone deacetylase hda-1 plays a pivotal role in this process by regulating signaling from the anchor cell (AC), the central organizer of uterine development. In hda-1 mutants, the utse fails to form, resulting in a defective or absent membrane at the apex of the vulva—a hallmark of disrupted morphogenesis.
To investigate this defect, we examined expression of p lineage-specific markers egl-13::gfp and lin-11::gfp in hda-1(RNAi) and hda-1(e1795) animals. In wild-type L3 larvae, six VU granddaughters adopt p fates, each giving rise to two daughters. By early L4 stage, these cells fuse with each other and the AC to form the utse. Both egl-13 and lin-11 are expressed in p cells and their progeny, and their activity is critical for proper division and fusion events. However, in hda-1 mutants, we observed a significant increase in the number of GFP-positive p-like cells—up to 10 in some animals—suggesting a failure to restrict p fate commitment. Furthermore, despite the increased number of p cells, their differentiation was impaired: the overall fluorescence intensity of lin-11::gfp was drastically reduced, and many cells lacked detectable expression altogether.
This paradoxical phenotype—more p-like cells but no functional utse—indicates that hda-1 is required not for p cell induction per se, but for their subsequent maturation and integration into the uterine structure. We also analyzed uv1 cell fate using ida-1::gfp, a marker specific to uv1 cells, which are derived from p progeny during L3 lethargus. In wild-type animals, four uv1 cells are clearly visible. In contrast, 96% of hda-1 mutants showed no ida-1::gfp expression, confirming a profound defect in uv1 specification. These findings demonstrate that hda-1 is essential for both p cell differentiation and the generation of downstream cell types necessary for a functional uterine–vulval junction.
The underlying mechanism involves hda-1’s function within the anchor cell. The AC produces the DSL ligand LAG-2, which activates LIN-12/Notch signaling in VU granddaughters to induce p fate. We found that hda-1 is expressed in the AC during mid-L3 stage, coinciding with the time of p cell induction. Knockdown of hda-1 led to a significant increase in lag-2::gfp fluorescence in the AC—by an average of 37%—indicating that hda-1 normally represses lag-2 expression.4-Chloro-6-fluoroquinazoline Biochemical Assay Reagents This overexpression likely causes ectopic activation of LIN-12/Notch signaling, leading to excessive p cell formation.Epacadostat Formula However, because these cells fail to differentiate properly, the net result is a loss of functional utse and uv1.PMID:35094218
To understand how hda-1 regulates lag-2, we investigated potential downstream effectors. We focused on two transcription factors known to act in the AC: nhr-67 and egl-43. Both are required for proper lag-2 expression and uterine cell fate specification. In hda-1(RNAi) animals, fluorescence of nhr-67::wcherry and egl-43::gfp in the AC was significantly reduced. Moreover, double RNAi experiments revealed that knockdown of either nhr-67 or egl-43 suppressed the elevated lag-2::gfp signal caused by hda-1 depletion. This genetic interaction demonstrates that nhr-67 and egl-43 act downstream of hda-1 to promote lag-2 expression, thereby mediating AC signaling.
These results support a model in which hda-1 functions as a transcriptional regulator in the AC to maintain appropriate levels of lag-2 through positive control of nhr-67 and egl-43. While hda-1 may also repress lag-2 in other contexts, its role in promoting lag-2 in the AC highlights a dual regulatory capacity. This balance ensures that LIN-12/Notch signaling is activated only when and where needed, preventing ectopic p cell formation while enabling correct uterine patterning.
In summary, our work establishes hda-1 as a key regulator of uterine cell fate specification. It acts in the anchor cell to fine-tune the expression of the LIN-12/Notch ligand lag-2 via nhr-67 and egl-43, thereby controlling the number and identity of p cells. This precise regulation is essential for the formation of the uterine seam cell and the integrity of the vulval–uterine connection. Given the conservation of HDAC1 and Notch pathway components across species, these findings provide insight into epigenetic mechanisms governing reproductive organ development and may inform understanding of related disorders in higher organisms.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com