Biology subjects

Garcia-Gonzalo, F. R.

Publications and source records attributed to Garcia-Gonzalo, F. R..

3 recordsLinked to original sources

bioRxiv2022

The male mouse meiotic cilium emanates from the mother centriole at zygotene prior to centrosome duplication

Cilia are hair-like projections of the plasma membrane with an inner microtubule skeleton known as axoneme. Motile cilia and flagella beat to displace extracellular fluids, playing important roles in the airways and reproductive system, among others. Instead, primary cilia function as cell type-dependent sensory organelles, detecting chemical, mechanical or optical signals from the extracellular environment. Cilia dysfunction is associated with genetic diseases called ciliopathies, and with some types of cancer. Cilia have been recently identified in zebrafish gametogenesis as an important regulator of the bouquet conformation and recombination. However, there is very little information about the structure and functions of cilia in mammalian meiosis. Here we describe the presence of cilia in male mouse meiotic cells. These solitary cilia form transiently in 20% of zygotene spermatocytes and reach considerable lengths (up to 15 m). CEP164 and CETN3 localization studies indicate that these cilia emanate from the mother centriole, prior to centrosome duplication. In addition, the study of telomeric TFR2 suggests that these cilia are not directly related to the bouquet conformation during early male mouse meiosis. Instead, based on TEX14 labeling of intercellular bridges in spermatocyte cysts, we suggest that mouse meiotic cilia may have sensory roles affecting cyst function during prophase I.

cell biology↗

bioRxiv2022

Multiple Ciliary Localization Signals Control INPP5E Ciliary Targeting

Primary cilia are sensory membrane protrusions whose dysfunction causes diseases named ciliopathies. INPP5E is a ciliary phosphoinositide phosphatase mutated in ciliopathies like Joubert syndrome. INPP5E regulates numerous ciliary functions, such as cilium stability, trafficking, signaling, or exovesicle release. Despite its key ciliary roles, how INPP5E accumulates in cilia remains poorly understood. Herein, we show that INPP5E ciliary targeting requires its folded catalytic domain and is controlled by four ciliary localization signals (CLSs), the first two of which we newly discover: LLxPIR motif (CLS1), W383 (CLS2), FDRxLYL motif (CLS3) and CaaX box (CLS4). We answer two long-standing questions in the field. First, partial redundancy between CLS1 and CLS4 explains why CLS4 is dispensable for ciliary targeting. Second, the essential need for CLS2 on the catalytic domain surface clarifies why CLS3 and CLS4 are together insufficient for ciliary accumulation. Furthermore, we reveal that some Joubert syndrome mutations in INPP5E catalytic domain affect its ciliary targeting, and shed light on the mechanisms of action of each CLS. Thus, we find that CLS2 and CLS3 promote interaction with TULP3 and ARL13B, while downregulating CEP164 binding. On the other hand, CLS4 recruits PDE6D, RPGR and ARL13B, and cooperates with CLS1 in ATG16L1 binding. Lastly, we show INPP5E immune synapse targeting is CLS-independent. Altogether, we reveal unusual complexity in INPP5E ciliary targeting mechanisms, likely reflecting its multiple key roles in ciliary biology.

cell biology↗

bioRxiv2020

Htr6 and Sstr3 ciliary targeting relies on both IC3 loops and C-terminal tails

G protein-coupled receptors (GPCRs) are the most common pharmacological target in clinical practice. To perform their signaling functions, many GPCRs must accumulate at primary cilia, microtubule-based plasma membrane protrusions that work as cellular antennae. Despite their great importance, the molecular mechanisms underlying GPCR ciliary targeting remain poorly understood. Serotonin receptor 6 (Htr6) and somatostatin receptor 3 (Sstr3) are two brain-enriched ciliary GPCRs controlling cognition and involved in multiple pathologies such as Alzheimers disease and cancer. We previously showed that the third intracellular loops (IC3s) of Htr6 and Sstr3 contain ciliary targeting sequences (CTSs) that are sufficient to confer ciliary localization to non-ciliary GPCRs. However, these CTSs are dispensable for the ciliary targeting of Htr6 and Sstr3 themselves, suggesting these GPCRs have additional CTSs. Herein, we show that the C-terminal tails of Htr6 and Sstr3 also contain CTSs, which act redundantly with those in the IC3s. Accordingly, simultaneous disruption of CTS1 (IC3) and CTS2 (C-terminal tail) abolishes ciliary targeting of both receptors. Mapping the individual residues required for Htr6 ciliary targeting reveals RKQ and LPG motifs critical for CTS1 and CTS2 function, respectively. In Sstr3, CTS1 function relies on the tandem AP[AS]CQ motifs and a subsequent arginine-rich stretch, whereas CTS2 operation requires the juxtamembrane residues. Furthermore, we shed light on the mechanisms of action of Htr6 CTSs by showing how they regulate binding to Tulp3 and Rabl2, two adapters needed for ciliary GPCR targeting.

cell biology↗