Prominins control ciliary length throughout the animal kingdom: New lessons from human prominin-1 and zebrafish prominin-3

Abstract

Prominins (proms) are transmembrane glycoproteins conserved throughout the animal kingdom. They are associated with plasma membrane protrusions, such as primary cilia, as well as extracellular vesicles derived thereof. Primary cilia host numerous signaling pathways affected in diseases known as ciliopathies. Human PROM1 (CD133) is detected in both somatic and cancer stem cells and is also expressed in terminally differentiated epithelial and photoreceptor cells. Genetic mutations in the PROM1 gene result in retinal degeneration by impairing the proper formation of the outer segment of photoreceptors, a modified cilium. Here, we investigated the impact of proms on two distinct examples of ciliogenesis. First, we demonstrate that the overexpression of a dominant-negative mutant variant of human PROM1 (i.e. mutation Y819F/Y828F) significantly decreases ciliary length in Madin–Darby canine kidney cells. These results contrast strongly to the previously observed enhancing effect of WT PROM1 on ciliary length. Mechanistically, the mutation impeded the interaction of PROM1 with ADP-ribosylation factor–like protein 13B, a key regulator of ciliary length. Second, we observed that in vivo knockdown of prom3 in zebrafish alters the number and length of monocilia in the Kupffer's vesicle, resulting in molecular and anatomical defects in the left-right asymmetry. These distinct loss-of-function approaches in two biological systems reveal that prom proteins are critical for the integrity and function of cilia. Our data provide new insights into ciliogenesis and might be of particular interest for investigations of the etiologies of ciliopathies.

Prom1 and Notch regulate ciliary length and dynamics in multiciliated cells of the airway epithelium

“…This mechanism is likely to be relevant in multiple biological contexts, since Prom1-containing membrane particles have been identified in a variety of body fluids, including urine, saliva, and seminal fluids (40). Studies in Madin-Darby Canine Kidney (MDCK) cells in which specific domains of Prom1 had been mutated suggest that the effect of Prom1 in cilia length can also involve interactions with ADP-ribosylation factor-like protein 13B (Arl13b), as well as cross-talking with cytoskeleton regulators in the cellular membrane microenvironment (14). Future work will clarify whether similar mechanisms are in place in airway multiciliated cells.…”

“…The association of Prominins with cilia appears to be well-conserved, as loss-of-function of these proteins results in various cilia-related phenotypes, including retinal degeneration and left-right asymmetry in non-mammalian species (14, 19). Interestingly, some of the Prom1-related ciliary phenotypes have also been linked to defects in Notch-signaling, a pathway involved in the development of both monociliated and multiciliated cells (14, 20, 21). In fact, Prom1 and Notch are known to interact in different cell types and contexts to regulate cellular behaviors (22).…”

Identification of novel disease relevant genetic modifiers affecting the SHH pathway in the developing brain

“…Interactions of ciliary components, e.g. prominin with ARL13b, have been shown to play a role in maintenance of length of the primary cilia throughout the animal kingdom (Jászai et al, 2020). Studies in mammalian cells suggest that increased soluble tubulin production leads to longer cilia and cytosolic tubulin stabilization results in shorter cilia (Sharma et al, 2011; Wang and Dynlacht, 2018; Wang et al, 2013).…”

An Update on Molecular Pathways Regulating Vasculogenic Mimicry in Human Osteosarcoma and Their Role in Canine Oncology

“…Little is still known about the mechanisms used by CSCs for promoting angiogenesis and VM ( 23 ). In this respect, the ability of CD133 to activate the Wingless-related integration site (Wnt) signaling pathway, thus increasing the expression of VEGFα and interleukin-8 (IL-8) ( 24 ), and its mechanistic link with cell motility ( 25 ), may be involved in the VM process.…”

“…Non-tumor canine cells, in particular MDCK cells, have been widely used for understanding the mechanisms on the basis of cell motility. In fact, considering that prominin-1 is associated with plasma membrane protrusions, the overexpression of Prom1 gene increased the number of MDCK microvilli, while the overexpression of a dominant-negative mutant variant significantly decreased ciliary length ( 25 ). The involvement of CD133 in cell motility was also demonstrated by Liu et al, showing the ability of isolated canine CD133+ epithelial cells to form a tubular-like structure when cultured on Matrigel ( 33 ).…”