bims-bicyki 2022-12-25 papers

bims-bicyki

Biomed News

on Bicaudal-C1 and interactors in cystic kidney disease

Issue of 2022–12–25
twenty-two papers selected by
Céline Gagnieux, École Polytechnique Fédérale de Lausanne

Primary Cilia Dysfunction in Neurodevelopmental Disorders beyond Ciliopathies.
The Role of Primary Cilia-Associated Phosphoinositide Signaling in Development.
Kidney concentrating capacity in children with autosomal recessive polycystic kidney disease is linked to glomerular filtration and hypertension.
miR-20a is upregulated in serum from domestic feline with PKD1 mutation.
Gallbladder cancer concomitant with autosomal dominant polycystic kidney disease: A case report.
Familial polycystic kidneys with no genetic confirmation: Are we sure it is ADPKD?
Primary Cilia: The New Face of Craniofacial Research.
The role of urinary supersaturations for lithogenic salts in the progression of autosomal dominant polycystic kidney disease.
Optical-Controlled Kinetic Switch: Fine-Tuning of the Residence Time of an Antagonist Binding to the Vasopressin V2 Receptor in In Vitro, Ex Vivo, and In Vivo Models of ADPKD.
Ciliary control of adipocyte progenitor cell fate regulates energy storage.
Islet cilia and glucose homeostasis.
Venglustat, a Novel Glucosylceramide Synthase Inhibitor, in Patients at Risk of Rapidly Progressing ADPKD: Primary Results of a Double-Blind, Placebo-Controlled, Phase 2/3 Randomized Clinical Trial.
Life-Saver or Undertaker: The Relationship between Primary Cilia and Cell Death in Vertebrate Embryonic Development.
Autosomal Dominant Tubulointerstitial Kidney Disease: An Emerging Cause of Genetic CKD.
Glucose absorption drives cystogenesis in a human organoid-on-chip model of polycystic kidney disease.
Mechanism of IFT-A polymerization into trains for ciliary transport.
The gymnastics of intraflagellar transport complexes keeps trains running inside cilia.
Cfap91-Dependent Stability of the RS2 and RS3 Base Proteins and Adjacent Inner Dynein Arms in Tetrahymena Cilia.
Cargo adapters expand the transport range of intraflagellar transport.
Effects of Y-27632, a ROCK inhibitor on Human Corneal Endothelial Cells Cultured by Isolating Human Corneal Endothelial Progenitor cells.
Endothelial β-arrestins regulate mechanotransduction by the type II bone morphogenetic protein receptor in primary cilia.
Icariin Treatment Rescues Diabetes Induced Bone Loss via Scavenging ROS and Activating Primary Cilia/Gli2/Osteocalcin Signaling Pathway.

J Dev Biol. 2022 Dec 13. pii: 54. [Epub ahead of print]10(4):

Primary Cilia Dysfunction in Neurodevelopmental Disorders beyond Ciliopathies.

Vasiliki Karalis, Kathleen E Donovan, Mustafa Sahin.

  Primary cilia are specialized, microtubule-based structures projecting from the surface of most mammalian cells. These organelles are thought to primarily act as signaling hubs and sensors, receiving and integrating extracellular cues. Several important signaling pathways are regulated through the primary cilium including Sonic Hedgehog (Shh) and Wnt signaling. Therefore, it is no surprise that mutated genes encoding defective proteins that affect primary cilia function or structure are responsible for a group of disorders collectively termed ciliopathies. The severe neurologic abnormalities observed in several ciliopathies have prompted examination of primary cilia structure and function in other brain disorders. Recently, neuronal primary cilia defects were observed in monogenic neurodevelopmental disorders that were not traditionally considered ciliopathies. The molecular mechanisms of how these genetic mutations cause primary cilia defects and how these defects contribute to the neurologic manifestations of these disorders remain poorly understood. In this review we will discuss monogenic neurodevelopmental disorders that exhibit cilia deficits and summarize findings from studies exploring the role of primary cilia in the brain to shed light into how these deficits could contribute to neurologic abnormalities.

Keywords:  ciliopathies; neurodevelopmental disorders; primary cilia; signaling

DOI:  https://doi.org/10.3390/jdb10040054
J Dev Biol. 2022 Dec 02. pii: 51. [Epub ahead of print]10(4):

The Role of Primary Cilia-Associated Phosphoinositide Signaling in Development.

Chuan Chen, Jinghua Hu, Kun Ling.

  Primary cilia are microtube-based organelles that extend from the cell surface and function as biochemical and mechanical extracellular signal sensors. Primary cilia coordinate a series of signaling pathways during development. Cilia dysfunction leads to a pleiotropic group of developmental disorders, termed ciliopathy. Phosphoinositides (PIs), a group of signaling phospholipids, play a crucial role in development and tissue homeostasis by regulating membrane trafficking, cytoskeleton reorganization, and organelle identity. Accumulating evidence implicates the involvement of PI species in ciliary defects and ciliopathies. The abundance and localization of PIs in the cell are tightly regulated by the opposing actions of kinases and phosphatases, some of which are recently discovered in the context of primary cilia. Here, we review several cilium-associated PI kinases and phosphatases, including their localization along cilia, function in regulating the ciliary biology under normal conditions, as well as the connection of their disease-associated mutations with ciliopathies.

Keywords:  development; phosphoinositide kinases and phosphatases; primary cilia

DOI:  https://doi.org/10.3390/jdb10040051
Pediatr Nephrol. 2022 Dec 20.

Kidney concentrating capacity in children with autosomal recessive polycystic kidney disease is linked to glomerular filtration and hypertension.

Tomáš Seeman, Kveta Bláhová, Filip Fencl, Richard Klaus, Bärbel Lange-Sperandio, Gabriela Hrčková, Ĺudmila Podracká.

   BACKGROUND: Impaired kidney concentration capacity is present in half of the patients with autosomal dominant polycystic kidney disease (ADPKD). The kidney concentrating capacity was further impaired within the animal model of autosomal recessive polycystic kidney disease (ARPKD). To date, only one small study has investigated it in children having ARPKD. Therefore, we aimed to study the kidney concentrating ability in a larger cohort of children with ARPKD.
METHODS: Eighteen children (median age 8.5 years, range 1.3-16.8) were retrospectively investigated. A standardized kidney concentrating capacity test was performed after the application of a nasal drop of desmopressin (urine osmolality > 900 mOsmol/kg). The glomerular filtration rate was estimated using the Schwartz formula (eGFR) and blood pressure (BP) was measured as office BP.
RESULTS: Kidney concentrating capacity was decreased (urine osmolality < 900 mOsmol/kg) in 100% of children with ARPKD. The median urine osmolality after desmopressin application was 389 (range 235-601) mOsmol/kg. Sixteen patients (89%) were defined as hypertensive based on their actual BP level or their use of antihypertensive drugs. The maximum amounts of urinary concentration correlated significantly with eGFR (r = 0.72, p < 0.0001) and hypertensive scores (r = 0.50, p < 0.05), but not with kidney size. Twelve patients (67%) were defined as having CKD stages 2-4. The median concentrating capacity was significantly lower in children within this group, when compared to children with CKD stage 1 possessing a normal eGFR (544 mOsmol/kg, range 413-600 mOsmol/kg vs. 327 mOsmol/kg, range 235-417 mOsmol/l, p < 0.001).
CONCLUSIONS: Impaired kidney concentrating capacity is present in most children with ARPKD and is associated with decreased eGFR and hypertension. A higher resolution version of the Graphical abstract is available as Supplementary information.

Keywords:  Glomerular filtration rate; Hypertension; Kidney length; Pediatric population

DOI:  https://doi.org/10.1007/s00467-022-05834-5
PLoS One. 2022 ;17(12): e0279337

miR-20a is upregulated in serum from domestic feline with PKD1 mutation.

Marcela Correa Scalon, Christine Souza Martins, Gabriel Ginani Ferreira, Franciele Schlemmer, Ricardo Titze de Almeida, Giane Regina Paludo.

Polycystic kidney disease (PKD), also known as autosomal dominant polycystic kidney disease (ADPKD) is a genetically heterogeneous condition characterized by cysts in renal parenchyma. It is the most prevalent inherited disease of domestic cats. MicroRNAs (miRNAs or ncRNA) are short, noncoding, single-stranded RNAs that may induce PKD cytogenesis by affecting numerous targets genes as well as by directly regulating PKD gene expression. We compared the relative expression profile of miR-20a, -192, -365, -15b-5p, and -16-5p from plasma and serum samples of nine domestic cats with PKD1 mutation, detected by polymerase chain reaction (PCR), and a control group (n = 10). Blood samples from cats with PKD1 mutation provide similar concentrations of microRNAs either from plasma or serum. Serum miR-20a is upregulated in PKD group with p < 0.005; Roc curve analysis showed an AUC of 90,1% with a cut-off value sensitivity of 77.8% and specificity of 100%. This data provides important information regarding renal miRNA expression in peripheral blood sampling.

DOI: https://doi.org/10.1371/journal.pone.0279337
Clin Case Rep. 2022 Dec;10(12): e6734

Gallbladder cancer concomitant with autosomal dominant polycystic kidney disease: A case report.

Hisashi Murakami, Satoshi Okubo, Masahiro Kobayashi, Miho Akabane, Masaru Matsumura, Junichi Shindoh, Masaji Hashimoto.

  The case is a 67-year-old female with autosomal dominant polycystic kidney disease who was followed up regularly. CT scan showed a mural nodule growing over the past 4 years inside the hypodense region surrounded by hepatic cysts. Surgery was performed and the pathological diagnosis was StageI gallbladder cancer.

Keywords:  ADPKD; TACE; gallbladder cancer

DOI:  https://doi.org/10.1002/ccr3.6734
Clin Nephrol. 2022 Dec 22.

Familial polycystic kidneys with no genetic confirmation: Are we sure it is ADPKD?

Manuela Rizzo, Ilaria Pezone, Maria Amicone, Ivana Capuano, Pasquale Buonanno, Eleonora Riccio, Antonio Pisani.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common heritable multifocal cystic disease encountered in clinical practice, and it is usually diagnosed in patients with family history by the evidence of markedly enlarged kidneys with multiple bilateral cysts at ultrasound (U.S.), computed tomography (CT) scan, or magnetic resonance imaging (MRI). In most cases, genetic testing is not required. Though ADPKD diagnosis is often straightforward, misdiagnosis is possible. Here we present a case of ADPKD misdiagnosis, followed by a review of the most important kidney heritable multifocal cystic diseases. Our case report demonstrates that ADPKD can be erroneously diagnosed when other kidney heritable multifocal cystic diseases occur without their distinguishing manifestations and when there is no genetic characterization among the relatives. A proper diagnosis of heritable diseases is crucial, as it allows an appropriate management of family members who carry disease allele, apart from patient management. Therefore, we suggest a careful differential diagnosis with possible molecular genetic analysis in presentations with familial cystic kidneys and suspicious clinical and radiological features.

DOI: https://doi.org/10.5414/CN110822
Biomolecules. 2022 Nov 22. pii: 1724. [Epub ahead of print]12(12):

Primary Cilia: The New Face of Craniofacial Research.

Emily R Moore.

  The primary cilium is a solitary, sensory organelle that extends from the surface of nearly every vertebrate cell, including craniofacial cells. This organelle converts chemical and physical external stimuli into intracellular signaling cascades and mediates several well-known signaling pathways simultaneously. Thus, the primary cilium is considered a cellular signaling nexus and amplifier. Primary cilia dysfunction directly results in a collection of diseases and syndromes that typically affect multiple organ systems, including the face and teeth. Despite this direct connection, primary cilia are largely unexplored in craniofacial research. In this review, I briefly summarize craniofacial abnormalities tied to the primary cilium and examine the existing information on primary cilia in craniofacial development and repair. I close with a discussion on preliminary studies that motivate future areas of exploration that are further supported by studies performed in long bone and kidney cells.

Keywords:  Hh signaling; Wnt signaling; calcium signaling; ciliopathies; cleft lip; cleft palate; dental pulp stem cells; neurons; odontoblasts; primary cilia

DOI:  https://doi.org/10.3390/biom12121724
J Nephrol. 2022 Dec 17.

The role of urinary supersaturations for lithogenic salts in the progression of autosomal dominant polycystic kidney disease.

Pietro Manuel Ferraro, Matteo Bargagli, Nicolas Faller, Manuel A Anderegg, Uyen Huynh-Do, Bruno Vogt, Giovanni Gambaro, Daniel G Fuster.

   BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is associated with significant risk of forming kidney stones, especially those made of calcium oxalate and uric acid, compared with the general population. Since crystals are able to activate the inflammasome and lead to cell injury, crystalluria might worsen ADPKD natural history, acting as a third hit.
METHODS: The Bern ADPKD registry is a prospective observational cohort study. Height-adjusted total kidney volume (ht-TKV) was measured at baseline and every 3 years. Twenty-four hour urinary solute excretions collected at baseline and eGFR measurements over time were included in this analysis. Twenty-four hour urinary supersaturations (SS) for calcium oxalate, calcium phosphate and uric acid were calculated using EQUIL-2. Linear regression models were used to assess linear and non-linear associations between slopes of ht-TKV and eGFR with SSs and 24 h urinary solute excretions.
RESULTS: Seventy-seven participants (mean age 45.0 [SD 12.9] years, eGFR 76.4 [28.3] mL/min/1.73 m2) were included, with a median follow-up of 4 years. The median slopes of ht-TKV and eGFR were 3.9 percent/year and 2.9 mL/min/1.73 m2/year, respectively. SS for uric acid showed a direct, linear association (p value for linearity 0.035) with ht-TKV slope. When analyzing individual components, urinary uric acid, ammonium, magnesium and sulfate were all directly associated with ht-TKV slope. Urinary sulfate was also directly associated with eGFR slope.
CONCLUSIONS: Uric acid supersaturation and several other urinary components are identified as predictors of cyst growth in patients with ADPKD. Future studies with a dedicated design are needed to investigate the pathophysiological mechanisms underlying these associations.

Keywords:  Autosomal dominant polycystic kidney disease; Crystalluria; Disease progression; Glomerular filtration rate; Urinary supersaturation

DOI:  https://doi.org/10.1007/s40620-022-01540-5
J Med Chem. 2022 Dec 23.

Optical-Controlled Kinetic Switch: Fine-Tuning of the Residence Time of an Antagonist Binding to the Vasopressin V2 Receptor in In Vitro, Ex Vivo, and In Vivo Models of ADPKD.

Xiaoke Gu, Haoxing Yuan, Wenchao Zhao, Nan Sun, Wenzhong Yan, Chunyu Jiang, Yan He, Hongli Liu, Jianjun Cheng, Dong Guo.

The pharmacological activity of a small-molecule ligand is linked to its receptor residence time. Therefore, precise control of the duration for which a ligand binds to its receptor is highly desirable. Herein, we designed photoswitchable ligands targeting the vasopressin V2 receptor (V2R), a validated target for autosomal dominant polycystic kidney disease (ADPKD). We adapted the photoswitching trait of azobenzene to the parent V2R antagonist lixivaptan (LP) to generate azobenzene lixivaptan derivatives (aLPs). Among them, aLPs-5g was a potential optical-controlled kinetic switch. Upon irradiation, cis-aLPs-5g displayed a 4.3-fold prolonged V2R residence time compared to its thermally stable trans configuration. The optical-controlled kinetic variations led to distinct inhibitory effects on cellular functional readout. Furthermore, conversion of the cis/trans isomer of aLPs-5g resulted in different efficacies of inhibiting renal cystogenesis ex vivo and in vivo. Overall, aLPs-5g represents a photoswitch for precise control of ligand-receptor residence time and, consequently, the pharmacological activity.

DOI: https://doi.org/10.1021/acs.jmedchem.2c01625
Front Cell Dev Biol. 2022 ;10 1083372

Ciliary control of adipocyte progenitor cell fate regulates energy storage.

Sierra R Scamfer, Mark D Lee, Keren I Hilgendorf.

  The primary cilium is a cellular sensory organelle found in most cells in our body. This includes adipocyte progenitor cells in our adipose tissue, a complex organ involved in energy storage, endocrine signaling, and thermogenesis. Numerous studies have shown that the primary cilium plays a critical role in directing the cell fate of adipocyte progenitor cells in multiple adipose tissue types. Accordingly, diseases with dysfunctional cilia called ciliopathies have a broad range of clinical manifestations, including obesity and diabetes. This review summarizes our current understanding of how the primary cilium regulates adipocyte progenitor cell fate in multiple contexts and illustrates the importance of the primary cilium in regulating energy storage and adipose tissue function.

Keywords:  adipocyte progenitor cells; adipose tissue; beige adipocyte; ciliopathies; diabetes; primary cilia; signaling; thermogenesis

DOI:  https://doi.org/10.3389/fcell.2022.1083372
Front Cell Dev Biol. 2022 ;10 1082193

Islet cilia and glucose homeostasis.

Isabella Melena, Jing W Hughes.

  Diabetes is a growing pandemic affecting over ten percent of the U.S. population. Individuals with all types of diabetes exhibit glucose dysregulation due to altered function and coordination of pancreatic islets. Within the critical intercellular space in pancreatic islets, the primary cilium emerges as an important physical structure mediating cell-cell crosstalk and signal transduction. Many events leading to hormone secretion, including GPCR and second-messenger signaling, are spatiotemporally regulated at the level of the cilium. In this review, we summarize current knowledge of cilia action in islet hormone regulation and glucose homeostasis, focusing on newly implicated ciliary pathways that regulate insulin exocytosis and intercellular communication. We present evidence of key signaling proteins on islet cilia and discuss ways in which cilia might functionally connect islet endocrine cells with the non-endocrine compartments. These discussions aim to stimulate conversations regarding the extent of cilia-controlled glucose homeostasis in health and in metabolic diseases.

Keywords:  beta cells; glucose regulation; pancreatic islets; paracrine signaling; primary cilia

DOI:  https://doi.org/10.3389/fcell.2022.1082193
Am J Kidney Dis. 2022 Dec 16. pii: S0272-6386(22)01079-4. [Epub ahead of print]

Venglustat, a Novel Glucosylceramide Synthase Inhibitor, in Patients at Risk of Rapidly Progressing ADPKD: Primary Results of a Double-Blind, Placebo-Controlled, Phase 2/3 Randomized Clinical Trial.

Ronald T Gansevoort, Ali Hariri, Pascal Minini, Curie Ahn, Arlene B Chapman, Shigeo Horie, Bertrand Knebelmann, Michal Mrug, Albert Cm Ong, York Pc Pei, Vicente E Torres, Vijay Modur, Igor Antonshchuk, Ronald D Perrone.

   RATIONALE AND OBJECTIVE: Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the formation of multiple kidney cysts that leads to growth in total kidney volume (TKV) and progression to kidney failure. Venglustat is a glucosylceramide synthase inhibitor that has been shown to inhibit cyst growth and reduce kidney failure in preclinical models of ADPKD.
STUDY DESIGN: STAGED-PKD was a two-stage, multicenter, double-blind, randomized, placebo-controlled Phase 2/3 study in adults with ADPKD at risk of rapidly progressive disease, selected based on Mayo Kidney Volume Class 1C-1E and an estimated glomerular filtration rate (eGFR) of 30-89.9 mL/min/1.73 m2.
SETTING AND PARTICIPANTS: Enrollment included 236 and 242 patients in Stages 1 and 2, respectively.
INTERVENTION(S): In Stage 1, patients were randomized 1:1:1 to venglustat 8 mg or 15 mg, or placebo. In Stage 2, patients were randomized 1:1 to venglustat 15 mg (highest dose identified as safe and well tolerated in Stage 1) or placebo.
OUTCOMES: Primary endpoints were rate of change in TKV over 18 months in Stage 1 and eGFR slope over 24 months in Stage 2. Secondary endpoints were eGFR slope over 18 months (Stage 1), rate of change in TKV (Stage 2), and safety/tolerability, pain, and fatigue (Stages 1 and 2).
RESULTS: A prespecified interim futility analysis showed that venglustat treatment had no effect on the annualized rate of change in TKV over 18 months (Stage 1) and had a faster rate of decline in eGFR slope over 24 months (Stage 2). Due to this lack of efficacy, the study was terminated early.
LIMITATIONS: The short follow-up after end-of-treatment and limited generalizability of findings.
CONCLUSIONS: In patients with rapidly progressing ADPKD, treatment with venglustat at either 8 mg or 15 mg showed no change in the rate of change in TKV and a faster rate of eGFR decline in the STAGED-PKD trial despite a dose-dependent decrease in plasma glucosylceramide (GL-1) levels.

Keywords:  Autosomal dominant polycystic kidney disease; glomerular filtration rate; total kidney volume; venglustat

DOI:  https://doi.org/10.1053/j.ajkd.2022.10.016
J Dev Biol. 2022 Dec 12. pii: 52. [Epub ahead of print]10(4):

Life-Saver or Undertaker: The Relationship between Primary Cilia and Cell Death in Vertebrate Embryonic Development.

Thorsten Pfirrmann, Christoph Gerhardt.

  The development of multicellular organisms requires a tightly coordinated network of cellular processes and intercellular signalling. For more than 20 years, it has been known that primary cilia are deeply involved in the mediation of intercellular signalling and that ciliary dysfunction results in severe developmental defects. Cilia-mediated signalling regulates cellular processes such as proliferation, differentiation, migration, etc. Another cellular process ensuring proper embryonic development is cell death. While the effect of cilia-mediated signalling on many cellular processes has been extensively studied, the relationship between primary cilia and cell death remains largely unknown. This article provides a short review on the current knowledge about this relationship.

Keywords:  apoptosis; axoneme; basal body; intraflagellar transport; transition zone

DOI:  https://doi.org/10.3390/jdb10040052
Kidney Int Rep. 2022 Nov;7(11): 2332-2344

Autosomal Dominant Tubulointerstitial Kidney Disease: An Emerging Cause of Genetic CKD.

Laura Econimo, Celine Schaeffer, Letizia Zeni, Roberta Cortinovis, Federico Alberici, Luca Rampoldi, Francesco Scolari, Claudia Izzi.

  Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare inherited disorder characterized by progressive loss of kidney function, nonsignificant urinalysis and tubulointerstitial fibrosis. ADTKD progresses to end stage renal disease (ESRD) in adulthood. The classification of ADTKD is an evolving concept and the agreement is now that, due to the overlap in terms of phenotype characteristics, this should be based on the involved gene. The umbrella term ADTKD therefore includes different conditions as follows: ADTKD-UMOD, ADKTD-MUC1, ADTKD-REN, and ADTK-HNF1B, with ADTKD-SEC61A1 and ADTKD-DNAJB11 as a further rare and atypical diagnosis recently described. The employment of next-generation sequencing (NGS) as a diagnostic tool in patients with familial kidney disease has improved the diagnostic accuracy in this field with ADTKD now being considered the third genetic cause of renal disease worldwide after autosomal dominant polycystic kidney disease (ADPKD) and Alport syndrome. On average, the disease pathogenesis is similar across the different subtypes, With the exception of HNF1B, the different mutated genes give rise to misfolded proteins leading to cellular stress and cytotoxicity. Research is now focused in better defining the underlying mechanism of fibrosis to guide therapeutic interventions. The aim of this review is to discuss how the knowledge of ADTKD has evolved in the last decades, with emphasis on the clinical features, molecular diagnosis, and pathogenic aspects of the different diseases included under the ADTKD term.

Keywords:  ADTKD; DNAJB11; HNF1B; MUC1; REN; UMOD

DOI:  https://doi.org/10.1016/j.ekir.2022.08.012
Nat Commun. 2022 Dec 23. 13(1): 7918

Glucose absorption drives cystogenesis in a human organoid-on-chip model of polycystic kidney disease.

Sienna R Li, Ramila E Gulieva, Louisa Helms, Nelly M Cruz, Thomas Vincent, Hongxia Fu, Jonathan Himmelfarb, Benjamin S Freedman.

In polycystic kidney disease (PKD), fluid-filled cysts arise from tubules in kidneys and other organs. Human kidney organoids can reconstitute PKD cystogenesis in a genetically specific way, but the mechanisms underlying cystogenesis remain elusive. Here we show that subjecting organoids to fluid shear stress in a PKD-on-a-chip microphysiological system promotes cyst expansion via an absorptive rather than a secretory pathway. A diffusive static condition partially substitutes for fluid flow, implicating volume and solute concentration as key mediators of this effect. Surprisingly, cyst-lining epithelia in organoids polarize outwards towards the media, arguing against a secretory mechanism. Rather, cyst formation is driven by glucose transport into lumens of outwards-facing epithelia, which can be blocked pharmacologically. In PKD mice, glucose is imported through cysts into the renal interstitium, which detaches from tubules to license expansion. Thus, absorption can mediate PKD cyst growth in human organoids, with implications for disease mechanism and potential for therapy development.

DOI: https://doi.org/10.1038/s41467-022-35537-2
Cell. 2022 Dec 22. pii: S0092-8674(22)01508-2. [Epub ahead of print]185(26): 4986-4998.e12

Mechanism of IFT-A polymerization into trains for ciliary transport.

Shimi Meleppattu, Haixia Zhou, Jin Dai, Miao Gui, Alan Brown.

  Intraflagellar transport (IFT) is the highly conserved process by which proteins are transported along ciliary microtubules by a train-like polymeric assembly of IFT-A and IFT-B complexes. IFT-A is sandwiched between IFT-B and the ciliary membrane, consistent with its putative role in transporting transmembrane and membrane-associated cargoes. Here, we have used single-particle analysis electron cryomicroscopy (cryo-EM) to determine structures of native IFT-A complexes. We show that subcomplex rearrangements enable IFT-A to polymerize laterally on anterograde IFT trains, revealing a cooperative assembly mechanism. Surprisingly, we discover that binding of IFT-A to IFT-B shields the preferred lipid-binding interface from the ciliary membrane but orients an interconnected network of β-propeller domains with the capacity to accommodate diverse cargoes toward the ciliary membrane. This work provides a mechanistic basis for understanding IFT-train assembly and cargo interactions.

Keywords:  cilia; cryo-EM; cryo-ET; flagella; intraflagellar transport; lipid binding; microtubule; molecular transport; vesicle

DOI:  https://doi.org/10.1016/j.cell.2022.11.033
Cell. 2022 Dec 22. pii: S0092-8674(22)01518-5. [Epub ahead of print]185(26): 4863-4865

The gymnastics of intraflagellar transport complexes keeps trains running inside cilia.

Maxence V Nachury.

The assembly and signaling properties of cilia rely on intraflagellar transport (IFT) trains moving proteins into, within, and out of cilia. A flurry of near-atomic models of the multiprotein complexes that make up IFT trains has revealed new conformational changes, which may underlie the switch between anterograde and retrograde intraflagellar transport.

DOI: https://doi.org/10.1016/j.cell.2022.12.005
Cells. 2022 Dec 14. pii: 4048. [Epub ahead of print]11(24):

Cfap91-Dependent Stability of the RS2 and RS3 Base Proteins and Adjacent Inner Dynein Arms in Tetrahymena Cilia.

Marta Bicka, Ewa Joachimiak, Paulina Urbanska, Anna Osinka, Anna Konopka, Ewa Bulska, Dorota Wloga.

  Motile cilia and eukaryotic flagella are specific cell protrusions that are conserved from protists to humans. They are supported by a skeleton composed of uniquely organized microtubules-nine peripheral doublets and two central singlets (9 × 2 + 2). Microtubules also serve as docking sites for periodically distributed multiprotein ciliary complexes. Radial spokes, the T-shaped ciliary complexes, repeat along the outer doublets as triplets and transduce the regulatory signals from the cilium center to the outer doublet-docked dynein arms. Using the genetic, proteomic, and microscopic approaches, we have shown that lack of Tetrahymena Cfap91 protein affects stable docking/positioning of the radial spoke RS3 and the base of RS2, and adjacent inner dynein arms, possibly due to the ability of Cfap91 to interact with a molecular ruler protein, Ccdc39. The localization studies confirmed that the level of RS3-specific proteins, Cfap61 and Cfap251, as well as RS2-associated Cfap206, are significantly diminished in Tetrahymena CFAP91-KO cells. Cilia of Tetrahymena cells with knocked-out CFAP91 beat in an uncoordinated manner and their beating frequency is dramatically reduced. Consequently, CFAP91-KO cells swam about a hundred times slower than wild-type cells. We concluded that Tetrahymena Cfap91 localizes at the base of radial spokes RS2 and RS3 and likely plays a role in the radial spoke(s) positioning and stability.

Keywords:  CFAP91; Tetrahymena; axoneme; cilia; radial spoke

DOI:  https://doi.org/10.3390/cells11244048
J Cell Sci. 2022 12 15. pii: jcs260408. [Epub ahead of print]135(24):

Cargo adapters expand the transport range of intraflagellar transport.

Karl Lechtreck.

  The assembly and maintenance of most cilia and eukaryotic flagella depends on intraflagellar transport (IFT), the bidirectional movement of multi-megadalton IFT trains along the axonemal microtubules. These IFT trains function as carriers, moving ciliary proteins between the cell body and the organelle. Whereas tubulin, the principal protein of cilia, binds directly to IFT particle proteins, the transport of other ciliary proteins and complexes requires adapters that link them to the trains. Large axonemal substructures, such as radial spokes, outer dynein arms and inner dynein arms, assemble in the cell body before attaching to IFT trains, using the adapters ARMC2, ODA16 and IDA3, respectively. Ciliary import of several membrane proteins involves the putative adapter tubby-like protein 3 (TULP3), whereas membrane protein export involves the BBSome, an octameric complex that co-migrates with IFT particles. Thus, cells employ a variety of adapters, each of which is substoichiometric to the core IFT machinery, to expand the cargo range of the IFT trains. This Review summarizes the individual and shared features of the known cargo adapters and discusses their possible role in regulating the transport capacity of the IFT pathway.

Keywords:  BBSome; Cilia; Dynein arms; Flagella; Intraflagellar transport; Radial spokes

DOI:  https://doi.org/10.1242/jcs.260408
Korean J Ophthalmol. 2022 Dec 22.

Effects of Y-27632, a ROCK inhibitor on Human Corneal Endothelial Cells Cultured by Isolating Human Corneal Endothelial Progenitor cells.

Haeeun Shin, Joon Ki Min, Na Rae Kim, Kyoung Yul Seo, Hee Seung Chin, Soyoung Lee, Ji Won Jung.

   Purpose: Human corneal endothelial progenitor cells (HCEPs), which has been selectively isolated and differentiated into human corneal endothelial cells (HCECs), are crucial for repairing corneal endothelial damage. In this study, we evaluated the roles of a ROCK inhibitor, Y-27632, on the isolation and expansion of HCEPs, and assessed the in vitro effects of different concentrations of Y-27632 on the differentiated HCEPs (HCECs).
Methods: HCEPs were isolated and expanded in a medium with and without 10 μM Y-27632, and then differentiated into HCECs in a medium with FBS. The characteristics of HCEP and differentiated HCEPs (HCECs) were confirmed by immunofluorescence staining. The proliferation, viability, morphology, and wound healing ability of HCECs were assessed in the presence of different concentrations of Y-27632.
Results: Y-27632 enabled the isolation and expansion of HCEPs from the corneal endothelium. The differentiated HCEPs (HCECs) showed an optimal increase in proliferation and survival in the presence of 10 μM Y-27632. As the concentration of Y-27632 increased, differentiated HCEPs (HCECs) became elongated, and actin filaments were redistributed to the periphery of cells. Y-27632 also caused a concentration-dependent enhancement in the wound healing ability of differentiated HCEPs (HCECs).
Conclusions: Y-27632 enabled the isolation and expansion of HCEPs. It also enhanced the proliferation, viability, and migration of differentiated HCEPs (HCECs).

Keywords:  ROCK inhibitor; corneal endothelial dysfunction; differentiated human corneal endothelial progenitor cells; human corneal endothelial cells; human corneal endothelial progenitor cells

DOI:  https://doi.org/10.3341/kjo.2022.0133
Pulm Circ. 2022 Oct;12(4): e12167

Endothelial β-arrestins regulate mechanotransduction by the type II bone morphogenetic protein receptor in primary cilia.

Saejeong Park, Zhiyuan Ma, Georgia Zarkada, Irinna Papangeli, Sarin Paluri, Nour Nazo, Felix Rivera-Molina, Derek Toomre, Sudarshan Rajagopal, Hyung J Chun.

  Modulation of endothelial cell behavior and phenotype by hemodynamic forces involves many signaling components, including cell surface receptors, intracellular signaling intermediaries, transcription factors, and epigenetic elements. Many of the signaling mechanisms that underlie mechanotransduction by endothelial cells are inadequately defined. Here we sought to better understand how β-arrestins, intracellular proteins that regulate agonist-mediated desensitization and integration of signaling by transmembrane receptors, may be involved in the endothelial cell response to shear stress. We performed both in vitro studies with primary endothelial cells subjected to β-arrestin knockdown, and in vivo studies using mice with endothelial specific deletion of β-arrestin 1 and β-arrestin 2. We found that β-arrestins are localized to primary cilia in endothelial cells, which are present in subpopulations of endothelial cells in relatively low shear states. Recruitment of β-arrestins to cilia involved its interaction with IFT81, a component of the flagellar transport protein complex in the cilia. β-arrestin knockdown led to marked reduction in shear stress response, including induction of NOS3 expression. Within the cilia, β-arrestins were found to associate with the type II bone morphogenetic protein receptor (BMPR-II), whose disruption similarly led to an impaired endothelial shear response. β-arrestins also regulated Smad transcription factor phosphorylation by BMPR-II. Mice with endothelial specific deletion of β-arrestin 1 and β-arrestin 2 were found to have impaired retinal angiogenesis. In conclusion, we have identified a novel role for endothelial β-arrestins as key transducers of ciliary mechanotransduction that play a central role in shear signaling by BMPR-II and contribute to vascular development.

Keywords:  BMPR2; beta‐arrestin; endothelial cells; primary cilia; shear stress

DOI:  https://doi.org/10.1002/pul2.12167
Cells. 2022 Dec 16. pii: 4091. [Epub ahead of print]11(24):

Icariin Treatment Rescues Diabetes Induced Bone Loss via Scavenging ROS and Activating Primary Cilia/Gli2/Osteocalcin Signaling Pathway.

Jie Liu, Qingfeng Cheng, Xiangmei Wu, Huifang Zhu, Xiaoyan Deng, Maorong Wang, Shengyong Yang, Jie Xu, Qian Chen, Mengxue Li, Xianjun Liu, Changdong Wang.

  Diabetes-associated bone complications lead to fragile bone mechanical strength and osteoporosis, aggravating the disease burden of patients. Advanced evidence shows that chronic hyperglycemia and metabolic intermediates, such as inflammatory factor, reactive oxygen species (ROS), and advanced glycation end products (AGEs), are regarded as dominant hazardous factors of bone complications, whereas the pathophysiological mechanisms are complex and controversial. By establishing a diabetic Sprague-Dawley (SD) rat model and diabetic bone loss cell model in vitro, we confirmed that diabetes impaired primary cilia and led to bone loss, while adding Icariin (ICA) could relieve the inhibitions. Mechanistically, ICA could scavenge ROS to maintain the mitochondrial and primary cilia homeostasis of osteoblasts. Intact primary cilia acted as anchoring and modifying sites of Gli2, thereby activating the primary cilia/Gli2/osteocalcin signaling pathway to promote osteoblast differentiation. All results suggest that ICA has potential as a therapeutic drug targeting bone loss induced by diabetes.

Keywords:  Icariin; ROS; bone loss; diabetes; primary cilia

DOI:  https://doi.org/10.3390/cells11244091