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Reddy Palicharla V, Mukhopadhyay S. Molecular and structural perspectives on protein trafficking to the primary cilium membrane. Biochem Soc Trans 2024; 52:1473-1487. [PMID: 38864436 DOI: 10.1042/bst20231403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/13/2024]
Abstract
The primary cilium is a dynamic subcellular compartment templated from the mother centriole or basal body. Cilia are solitary and tiny, but remarkably consequential in cellular pathways regulating proliferation, differentiation, and maintenance. Multiple transmembrane proteins such as G-protein-coupled receptors, channels, enzymes, and membrane-associated lipidated proteins are enriched in the ciliary membrane. The precise regulation of ciliary membrane content is essential for effective signal transduction and maintenance of tissue homeostasis. Surprisingly, a few conserved molecular factors, intraflagellar transport complex A and the tubby family adapter protein TULP3, mediate the transport of most membrane cargoes into cilia. Recent advances in cryogenic electron microscopy provide fundamental insights into these molecular players. Here, we review the molecular players mediating cargo delivery into the ciliary membrane through the lens of structural biology. These mechanistic insights into ciliary transport provide a framework for understanding of disease variants in ciliopathies, enable precise manipulation of cilia-mediated pathways, and provide a platform for the development of targeted therapeutics.
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Affiliation(s)
- Vivek Reddy Palicharla
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, U.S.A
| | - Saikat Mukhopadhyay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, U.S.A
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Lourdes SR, Gurung R, Giri S, Mitchell CA, McGrath MJ. A new role for phosphoinositides in regulating mitochondrial dynamics. Adv Biol Regul 2024; 91:101001. [PMID: 38057188 DOI: 10.1016/j.jbior.2023.101001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 11/27/2023] [Indexed: 12/08/2023]
Abstract
Phosphoinositides are a minor group of membrane-associated phospholipids that are transiently generated on the cytoplasmic leaflet of many organelle membranes and the plasma membrane. There are seven functionally distinct phosphoinositides, each derived via the reversible phosphorylation of phosphatidylinositol in various combinations on the inositol ring. Their generation and termination is tightly regulated by phosphatidylinositol-kinases and -phosphatases. These enzymes can function together in an integrated and coordinated manner, whereby the phosphoinositide product of one enzyme may subsequently serve as a substrate for another to generate a different phosphoinositide species. This regulatory mechanism not only enables the transient generation of phosphoinositides on membranes, but also more complex sequential or bidirectional conversion pathways, and phosphoinositides can also be transferred between organelles via membrane contacts. It is this capacity to fine-tune phosphoinositide signals that makes them ideal regulators of membrane organization and dynamics, through their recruitment of signalling, membrane altering and lipid transfer proteins. Research spanning several decades has provided extensive evidence that phosphoinositides are major gatekeepers of membrane organization, with roles in endocytosis, exocytosis, autophagy, lysosome dynamics, vesicular transport and secretion, cilia, inter-organelle membrane contact, endosome maturation and nuclear function. By contrast, there has been remarkably little known about the role of phosphoinositides at mitochondria - an enigmatic and major knowledge gap, with challenges in reliably detecting phosphoinositides at this site. Here we review recent significant breakthroughs in understanding the role of phosphoinositides in regulating mitochondrial dynamics and metabolic function.
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Affiliation(s)
- Sonia Raveena Lourdes
- Cancer Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Rajendra Gurung
- Cancer Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Saveen Giri
- Cancer Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Christina A Mitchell
- Cancer Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
| | - Meagan J McGrath
- Cancer Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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Bhat S, Dietz A, Senf K, Nietzsche S, Hirabayashi Y, Westermann M, Neuhaus EM. GPRC5C regulates the composition of cilia in the olfactory system. BMC Biol 2023; 21:292. [PMID: 38110903 PMCID: PMC10729543 DOI: 10.1186/s12915-023-01790-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/30/2023] [Indexed: 12/20/2023] Open
Abstract
BACKGROUND Olfactory sensory neurons detect odourants via multiple long cilia that protrude from their dendritic endings. The G protein-coupled receptor GPRC5C was identified as part of the olfactory ciliary membrane proteome, but its function and localization is unknown. RESULTS High-resolution confocal and electron microscopy revealed that GPRC5C is located at the base of sensory cilia in olfactory neurons, but not in primary cilia of immature neurons or stem cells. Additionally, GPRC5C localization in sensory cilia parallels cilia formation and follows the formation of the basal body. In closer examination, GPRC5C was found in the ciliary transition zone. GPRC5C deficiency altered the structure of sensory cilia and increased ciliary layer thickness. However, primary cilia were unaffected. Olfactory sensory neurons from Gprc5c-deficient mice exhibited altered localization of olfactory signalling cascade proteins, and of ciliary phosphatidylinositol-4,5-bisphosphat. Sensory neurons also exhibited increased neuronal activity as well as altered mitochondrial morphology, and knockout mice had an improved ability to detect food pellets based on smell. CONCLUSIONS Our study shows that GPRC5C regulates olfactory cilia composition and length, thereby controlling odour perception.
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Affiliation(s)
- Sneha Bhat
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany
| | - André Dietz
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany
| | - Katja Senf
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany
| | - Sandor Nietzsche
- Centre for Electron Microscopy, Jena University Hospital, Friedrich Schiller University Jena, Ziegelmühlenweg 1, 07743, Jena, Germany
| | - Yoshio Hirabayashi
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan
- RIKEN Cluster for Pioneering Research, RIKEN, Wako, Saitama, 351-0198, Japan
| | - Martin Westermann
- Centre for Electron Microscopy, Jena University Hospital, Friedrich Schiller University Jena, Ziegelmühlenweg 1, 07743, Jena, Germany
| | - Eva Maria Neuhaus
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany.
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Lee JJ, Ramadesikan S, Black AF, Christoffer C, Pacheco AFP, Subramanian S, Hanna CB, Barth G, Stauffacher CV, Kihara D, Aguilar RC. Heterogeneity in Lowe Syndrome: Mutations Affecting the Phosphatase Domain of OCRL1 Differ in Impact on Enzymatic Activity and Severity of Cellular Phenotypes. Biomolecules 2023; 13:615. [PMID: 37189363 PMCID: PMC10135975 DOI: 10.3390/biom13040615] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/23/2023] [Accepted: 03/25/2023] [Indexed: 04/01/2023] Open
Abstract
Lowe Syndrome (LS) is a condition due to mutations in the OCRL1 gene, characterized by congenital cataracts, intellectual disability, and kidney malfunction. Unfortunately, patients succumb to renal failure after adolescence. This study is centered in investigating the biochemical and phenotypic impact of patient's OCRL1 variants (OCRL1VAR). Specifically, we tested the hypothesis that some OCRL1VAR are stabilized in a non-functional conformation by focusing on missense mutations affecting the phosphatase domain, but not changing residues involved in binding/catalysis. The pathogenic and conformational characteristics of the selected variants were evaluated in silico and our results revealed some OCRL1VAR to be benign, while others are pathogenic. Then we proceeded to monitor the enzymatic activity and function in kidney cells of the different OCRL1VAR. Based on their enzymatic activity and presence/absence of phenotypes, the variants segregated into two categories that also correlated with the severity of the condition they induce. Overall, these two groups mapped to opposite sides of the phosphatase domain. In summary, our findings highlight that not every mutation affecting the catalytic domain impairs OCRL1's enzymatic activity. Importantly, data support the inactive-conformation hypothesis. Finally, our results contribute to establishing the molecular and structural basis for the observed heterogeneity in severity/symptomatology displayed by patients.
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Affiliation(s)
- Jennifer J. Lee
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Swetha Ramadesikan
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Adrianna F. Black
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Charles Christoffer
- Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA;
| | - Andres F. Pacheco Pacheco
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Sneha Subramanian
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Claudia B. Hanna
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Gillian Barth
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Cynthia V. Stauffacher
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Daisuke Kihara
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
- Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA;
| | - Ruben Claudio Aguilar
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; (J.J.L.); (A.F.B.); (A.F.P.P.); (S.S.); (C.B.H.); (G.B.); (C.V.S.); (D.K.)
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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