Biology subjects

Salzberg, A.

Publications and source records attributed to Salzberg, A..

4 recordsLinked to original sources

bioRxiv2026

Embryonic integrin signaling establishes a program of differential cell elongation in a growing proprioceptive organ

The ChO is a proprioceptive sensory organ that undergoes extensive morphological remodeling during larval growth. A key feature of this process is the dramatic elongation of cap cells, while adjacent ligament cells remain short. How these contrasting growth behaviors are established and coordinated is largely unknown. Using targeted RNAi screens of extracellular matrix (ECM) components, ECM receptors, and their intracellular effectors, we identified distinct molecular mechanisms controlling ChO architecture. We found that basement membrane components, including collagens and laminins, are required to maintain the characteristic straight morphology of cap cells, whereas Thrombospondin and Tiggrin contribute to the stability of cellular attachments. Unexpectedly, we discovered that Thrombospondin and an PS2{beta}PS integrin signaling module, comprising Talin and the ILK-PINCH-Parvin complex, regulate the relative lengths of cap and ligament cells. Cell-type-specific knockdown demonstrated that this pathway acts within ligament cells to restrict their elongation. Disruption of integrin signaling causes ligament cells to elongate dramatically at the expense of cap cell extension, effectively reversing their normal growth behaviors. Importantly, this function is distinct from the role of integrin-associated proteins in maintaining cellular attachments. Temporal manipulation of integrin expression revealed that the short morphology of ligament cells is established during a critical developmental time window during embryogenesis, before the organ becomes functional. Restoring integrin expression after hatching fails to rescue the phenotype, indicating that embryonic integrin signaling establishes a persistent developmental state. Together, these findings reveal that ligament cell elongation is actively restricted by an embryonically established integrin-dependent mechanism, providing the structural basis for subsequent cap cell elongation and organ maturation.

developmental biology↗

bioRxiv2026

A mechanical time window for correct proprioceptor development

Proprioception requires the transduction of mechanical strain generated by muscle contractions into sensory neuron activity. Although mechanical forces are essential for the function of mechanosensory organs, their role in the development of these organs remains largely unknown. It was already shown that the fly chordotonal organ (ChO), a multicellular proprioceptor, must acquire correct mechanical properties for proper function. Here, using an in vivo approach, we identify a critical mechanical time window during which the ChOs must experience appropriate mechanical forces to acquire the mechanical properties required for sensory function. To define this developmental window, we downregulated Pericardin (Prc), a major component of the ChO extracellular matrix, at different time points during embryonic and larval development. We then measured in vivo the efficiency with which muscle-generated deformations are converted into compressive strain in the ChO cap cell, a key step in transmitting mechanical forces to the sensory neuron. The most severe effect on conversion efficiency was evident when prc was downregulated during late embryogenesis, a time window which coincides with the onset of embryonic muscle contractions. This observation suggests that muscle-generated forces provide developmental cues required for the development of ChOs with correct mechanical properties. Consistent with this hypothesis, reducing muscle-generated forces during the same embryonic period resulted in a similar phenotype of impaired ChO mechanics and sensory function. Together, our findings reveal a previously unknown role for muscle-generated forces in shaping the development of fully functional proprioceptors.

developmental biology↗

bioRxiv2021

Revisiting the role of beta-tubulin in Drosophila development: beta-tubulin60D is not an essential gene, and its novel Pin1 allele has a tissue-specific dominant-negative impact

Diversity in cytoskeleton organization and function may be achieved through alternative tubulin isotypes and by a variety of post-translational modifications. The Drosophila genome contains five different {beta}-tubulin paralogs, which may play an isotype tissue-specific function in vivo. One of these genes, the beta-tubulin60D gene, which is expressed in a tissue-specific manner, was found to be essential for fly viability and fertility. To further understand the role of the beta-tubulin60D gene, we generated new beta-tubulin60D null alleles (beta-tubulin60DM) using the CRISPR/Cas9 system and found that the homozygous flies were viable and fertile. Moreover, using a combination of genetic complementation tests, rescue experiments, and cell biology analyses, we identified Pin1, an unknown dominant mutant with bristle developmental defects, as a dominant-negative allele of beta-tubulin60D. We also found a missense mutation in the Pin1 mutant that results in an amino acid replacement from the highly conserved glutamate at position 75 to lysine (E75K). Analyzing the {beta}-tubulin structure suggests that this E75K alteration destabilizes the alpha-helix structure and may also alter the GTP-Mg2+ complex binding capabilities. Our results revisited the credence that beta-tubulin60D is required for fly viability and revealed for the first time in Drosophila, a novel dominant-negative function of missense beta-tubulin60D mutation in bristle morphogenesis. Author summaryDiversity in cell microtubule cytoskeleton organization and function may be achieved through alternative tubulin isotypes and by a variety of post-translational modifications. The expression pattern of different tubulin isotypes (both and {beta} subunits) can vary according to cell type and stage of development, which contribute significantly to cell-specific MT organization and function. In this study, we revisited the role of one of the beta-tubulin isotopes in Drosophila, namely, beta-tubulin60D. This is the first study where a well molecularly defined protein null allele of {beta}Tub60D was generated and characterized. This well-characterized {beta}Tub60D allele demonstrated unambiguity that {beta}Tub60D is not an essential gene, as was described before. Moreover, we identified Pin1, an unknown dominant mutant with bristle developmental defects, as a dominant-negative allele of beta-tubulin60D. We also found a missense mutation in the Pin1 mutant that results in an amino acid (E75K). Analyzing the {beta}-tubulin structure suggests that this E75K alteration destabilizes the alpha-helix structure and may also alter GTP-Mg2+ complex binding capabilities. Thus, our results also revealed for the first time in Drosophila, a novel dominant-negative function of a missense beta-tubulin60D mutation, which has a tissue-specific function.

developmental biology↗

bioRxiv2021

delilah, prospero and D-Pax2 constitute a gene regulatory network essential for the development of functional proprioceptors

Coordinated animal locomotion depends on the development of functional proprioceptors. While early cell-fate determination processes are well characterized, little is known about the terminal differentiation of cells within the proprioceptive lineage and the genetic networks that control them. In this work we describe a gene regulatory network consisting of three transcription factors-Prospero (Pros), D-Pax2 and Delilah (Dei)-that dictates two alternative differentiation programs within the proprioceptive lineage in Drosophila. We show that D-Pax2 and Pros control the differentiation of cap versus scolopale cells in the chordotonal organ lineage by, respectively, activating and repressing the transcription of dei. Normally, D-Pax2 activates the expression of dei in the cap cell but is unable to do so in the scolopale cell where Pros is co-expressed. We further show that D-Pax2 and Pros exert their effects on dei transcription via a 262 bp chordotonal-specific enhancer in which two D-Pax2- and three Pros-binding sites were identified experimentally. When this enhancer was removed from the fly genome, the cap- and ligament-specific expression of dei was lost, resulting in loss of chordotonal organ functionality and defective larval locomotion. Thus, coordinated larval locomotion depends on the activity of a dei enhancer that integrates both activating and repressive inputs for the generation of a functional proprioceptive organ.

developmental biology↗