Biology subjects

Lapart, J.-A.

Publications and source records attributed to Lapart, J.-A..

4 recordsLinked to original sources

bioRxiv2026

Cfap410a and Cby work together with tissue-specific requirements to build Drosophila ciliary transition zones

Cilia and flagella perform essential physiological functions in eukaryotes, and defects in these organelles cause several human diseases, including cancer and ciliopathies. The architecture of cilia is highly organized. The ciliary compartment is separated from the cytoplasm by the transition zone (TZ). The severity of ciliopathies linked to TZ assembly defects highlights the TZ's critical role. Although several core conserved complexes are involved in TZ assembly, variations in TZ composition are associated with structurally and functionally diverse cilia. Here, we identify Cfap410a as a novel component of the ciliary TZ in the two Drosophila ciliated tissues, male germ cells and sensory neurons. Cfap410a is one of the two Drosophila paralogs (Cfap410a and Cfap410b) of human CFAP410, whose mutations are associated with axial spondylo-metaphyseal dysplasia, retinitis pigmentosa and amyotrophic lateral sclerosis. We show here that Cfap410a is a proximity partner of Cby and that they act cooperatively in the hierarchy of the TZ assembly program by bridging the CEP290 and MKS transition zone modules. Simultaneous loss of Cfap410a and Cby halts ciliary growth by disrupting TZ formation in multiple types of Drosophila ciliated cells, each of which exhibiting varying dependence on these two proteins. Interestingly, the function of Cfap410a and Cfap410b are not functionally redundant, indicating that the two proteins have evolved towards specific functions. In summary, our results propose a novel role for CFAP410a at the TZ and provide an explanation for how deregulation of conserved TZ components could lead to tissue-specific ciliopathies.

cell biology↗

bioRxiv2025

Putative interfollicular stem cells of skin epidermis possess a specific mechanical signature that evolves during aging

Skin homeostasis and self-renewal are partially maintained by interfollicular stem cells (ISCs), located in the basal layer above the dermal papillae of the dermo-epidermal junction (DEJ). Aging leads to a decline in skin renewal and a concurrent reduction in stem cell potential. It is also marked by disorganization of the extracellular matrix in both the DEJ and dermis, and flattening of the DEJ. To better understand ISC aging, new methods are needed to characterize ISCs and their environment. Since mechanical properties of cells and their substrate influence cell fate, we employed atomic force microscopy to explore whether ICSs niches and the DEJ exhibit distinct mechanical properties. Our findings reveal that ISCs possess greater stiffness than other basal cells, a mechanical signature that diminishes with age. Additionally, the DEJ beneath ISCs shows higher stiffness than under other basal cells, providing ISCs with a specific mechanical environment, which also deteriorates during aging. In vitro, sorting of ISCs based on MCSP expression effectively isolates ISCs beneath the dermal papillae, allowing the measurement of their mechanical signature and stemness potential under varying mechanical conditions. The study of ISC mechanical signatures offers a promising approach for characterizing 3D skin models and understanding defects in skin renewal and wound healing.

cell biology↗

bioRxiv2023

Alstrom syndrome proteins are novel regulators of centriolar cartwheel assembly and centrosome homeostasis in Drosophila

Centrioles play a central role in cell division by recruiting pericentriolar material (PCM) to form the centrosome. Alterations in centriole number or function lead to various diseases including cancer or microcephaly. Centriole duplication is a highly conserved mechanism in eukaryotes. Here, we show that the two Drosophila orthologs of the Alstrom syndrome protein 1 (Alms1a and Alms1b) are unexpected novel players of centriole duplication in fly. Using Ultrastructure Expansion Microscopy, we reveal that Alms1a is a PCM protein that is loaded proximally on centrioles at the onset of procentriole formation whereas Alms1b caps the base of mature centrioles. We demonstrate that chronic loss of Alms1 proteins affects PCM maturation, whereas their acute loss completely disrupts procentriole formation before Sas-6 cartwheel assembly. We establish that Alms1 proteins are required for the amplification of the Plk4-Ana2 pool at the duplication site and the subsequent Sas-6 recruitment. Thus, Alms1 proteins are novel critical but highly buffered regulators of PCM and cartwheel assembly in flies.

cell biology↗

bioRxiv2023

EASYSTIFF(R), a portable and innovative device able to separately analyze each skin compartment for the evaluation of mechanical properties.

Human skin is submitted to various factors leading to either extrinsic or intrinsic aging. In addition to inducing molecular and morphological changes, skin aging is characterized by modifications in skin biomechanical properties modifications. These modifications can be used as biomarkers to both evaluate the degree of advancement in skin aging but also to detect potential pathologies. Hence, it is from critical interest to be able to evaluate skin biomechanical properties to fully detect and monitor these alterations. Here we introduce a portable and innovative (R)device, EASYSTIFF(R), which is thought to in vivo measure stiffness properties of skin. Based on indentation principle, EASYSTIFF allows to identify both global stiffness of skin (all confounded cutaneous compartment) or compartmentalized stiffness, in which stiffness values of each compartment, i.e., the stratum corneum, the epidermis, the dermis and the hypodermis, are separately analyzed. Thus, EASYSTIFF is a complementary tool to 2D and 3D in/ex vivo model and an alternative to existing devices that measure skin mechanical properties, for assessing the effectiveness of cosmetic products, monitoring skin stiffness over time and to provide better understanding in the evolution of skin mechanical properties.

biophysics↗