Consensus nomenclature for dyneins and associated assembly factors

Dyneins are highly complex, multicomponent, microtubule-based molecular motors. These enzymes are responsible for numerous motile behaviors in cytoplasm, mediate retrograde intraflagellar transport (IFT), and power ciliary and flagellar motility. Variants in multiple genes encoding dyneins, outer dynein arm (ODA) docking complex subunits, and cytoplasmic factors involved in axonemal dynein preassembly (DNAAFs) are associated with human ciliopathies and are of clinical interest. Therefore, clear communication within this field is particularly important. Standardizing gene nomenclature, and basing it on orthology where possible, facilitates discussion and genetic comparison across species. Here, we discuss how the human gene nomenclature for dyneins, ODA docking complex subunits, and DNAAFs has been updated to be more functionally informative and consistent with that of the unicellular green alga Chlamydomonas reinhardtii, a key model organism for studying dyneins and ciliary function. We also detail additional nomenclature updates for vertebrate-specific genes that encode dynein chains and other proteins involved in dynein complex assembly.

Effects of Long-Acting Muscarinic Antagonists on Promoting Ciliary Function in Airway Epithelium

Background Mucociliary clearance (MCC) is an essential defense mechanism in airway epithelia for removing pathogens from the respiratory tract. Impaired ciliary functions and MCC have been demonstrated in asthma and chronic obstructive pulmonary disease (COPD). Long-acting muscarinic antagonists (LAMAs) are a major class of inhaled bronchodilators, which are used for treating asthma and COPD; however, the effects of LAMAs on ciliary function remain unclear. This study aimed to identify the effects of LAMAs on airway ciliary functions. Methods Wild-type BALB/c mice were treated with daily intranasal administrations of glycopyrronium for 7 days, and tracheal samples were collected. Cilia-driven flow and ciliary activity, including ciliary beat frequency (CBF), ciliary beating amplitude, effective stroke velocity, recovery stroke velocity and the ratio of effective stroke velocity to recovery stroke velocity, were analyzed by imaging techniques. Using in vitro murine models, tracheal tissues were transiently cultured in media with/without LAMAs, glycopyrronium or tiotropium, for 60 min. Cilia-driven flow and ciliary activity were then analyzed. Well-differentiated normal human bronchial epithelial (NHBE) cells were treated with glycopyrronium, tiotropium, or vehicle for 60 min, and CBF was evaluated. Several mechanistic analyses were performed. Results Intranasal glycopyrronium administration for 7 days significantly increased cilia-driven flow and ciliary activity in murine airway epithelium. In the murine tracheal organ culture models, treatment with glycopyrronium or tiotropium for 60 min significantly increased cilia-driven flow and ciliary activity in airway epithelium. Further, we confirmed that 60-min treatment with glycopyrronium or tiotropium directly increased CBF in well-differentiated NHBE cells. In the mechanistic analyses, neither treatment with glycopyrronium nor tiotropium affected intracellular calcium ion concentrations in well-differentiated NHBE cells. Glycopyrronium did not increase protein kinase A activity in well-differentiated NHBE cells. Moreover, glycopyrronium had no effect on extracellular adenosine triphosphate concentration. Conclusions LAMAs exert a direct effect on airway epithelium to enhance ciliary function, which may improve impaired MCC in asthma and COPD. Further investigations are warranted to elucidate the underlying mechanisms of the effects of LAMAs on the promotion of airway ciliary function.

Angiomotin isoform 2 promotes binding of PALS1 to KIF13B at the base of primary cilia and suppresses ciliary elongation

The kinesin-3 motor KIF13B functions in endocytosis, vesicle transport, and regulation of ciliary length and signaling. Direct binding of the membrane-associated guanylate kinase (MAGUK) DLG1 to KIF13Bs MAGUK-binding stalk (MBS) domain relieves motor autoinhibition and promotes microtubule plus end-directed cargo transport. Here we characterize Angiomotin isoform 2 (Ap80) as a novel KIF13B interactor that promotes binding of another MAGUK, the polarity protein and Crumbs complex component PALS1, to KIF13B. Live cell imaging analysis indicated that Ap80 is concentrated at the base of primary cilia and recruits PALS1 to this site, but is not itself a cargo of KIF13B. Consistent with a ciliary function for Ap80, its depletion led to elongated primary cilia and altered IGF-1 signaling in cultured mammalian cells. Our results suggest that Ap80 may specifically activate KIF13B cargo binding at the base of primary cilia to regulate ciliary length and signaling.

Effects of Long-acting Muscarinic Antagonists on Promoting Ciliary Function in Airway Epithelium

BackgroundMucociliary clearance (MCC) is an essential defense mechanism in airway epithelia for removing pathogens from the respiratory tract. Impaired ciliary functions and MCC have been demonstrated in asthma and chronic obstructive pulmonary disease (COPD). Long-acting muscarinic antagonists (LAMAs) are a major class of inhaled bronchodilators, which are used for treating asthma and COPD; however, the effects of LAMAs on ciliary function remain unclear. This study aimed to identify the effects of LAMAs on airway ciliary functions.MethodsWild-type BALB/c mice were treated with daily intranasal administrations of glycopyrronium for 7 days, and tracheal samples were collected. Cilia-driven flow and ciliary activity, including ciliary beat frequency (CBF), ciliary beating amplitude, effective stroke velocity, recovery stroke velocity and the ratio of effective stroke velocity to recovery stroke velocity, were analyzed by imaging techniques. Using in vitro murine models, tracheal tissues were transiently cultured in media with/without LAMAs, glycopyrronium or tiotropium, for 60 min. Cilia-driven flow and ciliary activity were then analyzed. Well-differentiated normal human bronchial epithelial (NHBE) cells were treated with glycopyrronium, tiotropium, or vehicle for 60 min, and CBF was evaluated. Several mechanistic analyses were performed.ResultsIntranasal glycopyrronium administration for 7 days significantly increased cilia-driven flow and ciliary activity in murine airway epithelium. In the murine tracheal organ culture models, treatment with glycopyrronium or tiotropium for 60 min significantly increased cilia-driven flow and ciliary activity in airway epithelium. Further, we confirmed that 60-min treatment with glycopyrronium or tiotropium directly increased CBF in well-differentiated NHBE cells. In the mechanistic analyses, neither treatment with glycopyrronium nor tiotropium affected intracellular calcium ion concentrations in well-differentiated NHBE cells. Glycopyrronium did not increase protein kinase A activity in well-differentiated NHBE cells. Moreover, glycopyrronium had no effect on extracellular adenosine triphosphate concentration.ConclusionsLAMAs exert a direct effect on airway epithelium to enhance ciliary function, which may improve impaired MCC in asthma and COPD. Further investigations are warranted to elucidate the underlying mechanisms of the effects of LAMAs on the promotion of airway ciliary function.

Proteomic analysis of microtubule inner proteins (MIPs) in Rib72 null Tetrahymena cells reveals functional MIPs

The core structure of motile cilia and flagella, the axoneme, is built from a stable population of doublet microtubules. This unique stability is brought about, at least in part, by a network of Microtubule Inner Proteins (MIPs) that are bound to the luminal side of the microtubule walls. Rib72A and Rib72B were identified as MIPs in the motile cilia of the protist Tetrahymena thermophila. Loss of these proteins leads to ciliary defects and loss of additional MIPs. We performed mass spectrometry coupled with proteomic analysis and bioinformatics to identify the MIPs lost in RIB72A/B knockout Tetrahymena axonemes. We identified a number of candidate MIPs and pursued one, Fap115, for functional characterization. We find that loss of Fap115 results in disrupted cell swimming and aberrant ciliary beating. Cryo-electron tomography reveals that Fap115 localizes to MIP6a in the A-tubule of the doublet microtubules. Overall, our results highlight the complex relationship between MIPs, ciliary structure, and ciliary function.

Hypothalamic primary cilium: A hub for metabolic homeostasis

Obesity is a global health problem that is associated with adverse consequences such as the development of metabolic disorders, including cardiovascular disease, neurodegenerative disorders, and type 2 diabetes. A major cause of obesity is metabolic imbalance, which results from insufficient physical activity and excess energy intake. Understanding the pathogenesis of obesity, as well as other metabolic disorders, is important in the development of methods for prevention and therapy. The coordination of energy balance takes place in the hypothalamus, a major brain region that maintains body homeostasis. The primary cilium is an organelle that has recently received attention because of its role in controlling energy balance in the hypothalamus. Defects in proteins required for ciliary function and formation, both in humans and in mice, have been shown to cause various metabolic disorders. In this review, we provide an overview of the critical functions of primary cilia, particularly in hypothalamic areas, and briefly summarize the studies on the primary roles of cilia in specific neurons relating to metabolic homeostasis.

The impact of zinc supplementation on the outcome of endoscopic sinus surgery and ciliary function of the nasal mucosa in children with chronic rhinosinusitis

Несмотря на указания на роль цинка в функции реснитчатого эпителия, данные относительно влияния коррекции обмена цинка на цилиарную функцию у пациентов с хроническим риносинуситом отсутствуют. Целью настоящего исследования явилась оценка эффективности хирургического лечения, активности мукоцилиарного аппарата, а также местной воспалительной реакции слизистой оболочки носа в послеоперационном периоде у детей с хроническим риносинуситом на фоне применения цинка. Методы. Обследовано 192 ребенка с хроническим риносинуситом, в лечении которых применялась эндоскопическая риносинусохирургия. Из них 131 ребенок в послеоперационном периоде получал стандартные назначения, тогда как 61 ребенок дополнительно получал цинк в суточной дозе 10 мг в течение 90 дней. Оценка концентрации цинка в сыворотке крови осуществлялась методом ИСП-МС. Для определения функции цилий использована видеоцитоморфометрия. Определение эффективности лечения осуществлялось с использованием опросника SNOT-20, а также шкал Лунд-Кеннеди и Лунд-Маккей. Результаты. Проведение эндоскопической операции приводило к достоверному снижению значений шкал SNOT-20, Лунд-Кеннеди и Лунд-Маккей у пациентов вне зависимости от приема цинка. В то же время, пациенты, принимавшие цинк, характеризовались достоверно меньшим риском ревизионной хирургии. Цинк также оказывал значительное влияние на функционирование реснитчатого эпителия. В частности, к 12-му месяцу наблюдения количество клеток с подвижными цилиями, частота биения цилий, длина цилий и выживаемость клеток у пациентов, принимавших цинк, превышала соответствующие показатели в контрольной группе. Повышение уровня цинка в организме также сопровождалось многократным снижением количества инфильтрирующих слизистую оболочку нейтрофилов и лимфоцитов. Заключение. Предполагается, что цинк ускоряет репаративные процессы в слизистой оболочке носа и обладает противовоспалительным действием. Despite the presence of certain indications of the role of zinc in ciliated epithelium functioning, data on the potential effect of Zn supplementation in ciliary function in patients with chronic rhinosinusitis are absent. The aim of this study was to evaluate the efficiency of surgical treatment, ciliary activity, as well as local inflammation of nasal mucosa in children with chronic rhinosinusitis undergoing functional endoscopic surgery. Methods. 192 pediatric patients with chronic rhinosinusitis were examined. 131 patients received standard postoperative prescriptions, whereas 61 children received 10 mg Zn daily for 90 days. Serum Zn concentrations were measured by inductively coupled plasma mass spectrometry. Ciliary function was evaluated by video cytomorphometry. Surgery efficiency was assessed with a SNOT-20 questionnaire, as well as with Lund-Kennedy and Lund-Mackay scales. Results. Functional endoscopic sinus surgery resulted in a significant decrease in total SNOT-20, Lund-Kennedy, and Lund-Mackay scores independent of Zn supplementation. At the same time, Zn supplemented patients had a significantly lower risk of revision surgery. Zn also had a significant impact on ciliary function. Specifically, up to the 12th mo postoperatively, Zn supplementation resulted in higher number of cells with motile cilia, ciliary beat frequency, ciliary length, and cell viability as compared to controls. Increased Zn status was also associated with a manyfold decrease in mucosal neutrophil and lymphocyte infiltration. Conclusions. It is proposed that Zn enhances reparative processes in nasal mucosa and possesses anti-inflammatory activity.