bims-bicyki 2021-11-07 papers

bims-bicyki

Biomed News

on Bicaudal-C1 and interactors in cystic kidney disease

Issue of 2021–11–07
fiveteen papers selected by
Céline Gagnieux, École Polytechnique Fédérale de Lausanne

Polycystic Liver Disease: Advances in Understanding and Treatment.
Genetic testing, ultrasonography and preimplantation genetic testing of men with autosomal dominant polycystic kidney disease in Hunan, China.
Screening of QTc interval and global autonomic activity in autosomal dominant polycystic kidney disease and atherosclerotic renal artery stenosis hypertensive patients.
Reversing polycystic kidney disease.
xbx-4, a homolog of the Joubert syndrome gene FAM149B1, acts via the CCRK and RCK kinase cascade to regulate cilia morphology.
Mainstreaming Genetic Testing for Adult Patients With Autosomal Dominant Polycystic Kidney Disease.
Early childhood height-adjusted total kidney volume as a risk marker of kidney survival in ARPKD.
Vangl2 participates in the primary ciliary assembly under low fluid shear stress in hUVECs.
Hypoxia induces stress fiber formation in adipocytes in the early stage of obesity.
Will advances in functional renal MRI translate to the nephrology clinic?
WDR60-mediated dynein-2 loading into cilia powers retrograde IFT and transition zone crossing.
Identification of a novel variant of the ciliopathic gene FUZZY associated with craniosynostosis.
A WDR35-dependent coat protein complex transports ciliary membrane cargo vesicles to cilia.
Biallelic ANKS6 mutations cause late onset ciliopathy with chronic kidney disease through YAP dysregulation.
Paxillin controls actin stress fiber formation and migration of vascular smooth muscle cells by directly binding to the active Fyn.

Annu Rev Pathol. 2021 Nov 01.

Polycystic Liver Disease: Advances in Understanding and Treatment.

Tatyana V Masyuk, Anatoliy I Masyuk, Nicholas F LaRusso.

Polycystic liver disease (PLD) is a group of genetic disorders characterized by progressive development of cholangiocyte-derived fluid-filled hepatic cysts. PLD is the most common manifestation of autosomal dominant and autosomal recessive polycystic kidney diseases and rarely occurs as autosomal dominant PLD. The mechanisms of PLD are a sequence of the primary (mutations in PLD-causative genes), secondary (initiation of cyst formation), and tertiary (progression of hepatic cystogenesis) interconnected molecular and cellular events in cholangiocytes. Nonsurgical, surgical, and limited pharmacological treatment options are currently available for clinical management of PLD. Substantial evidence suggests that pharmacological targeting of the signaling pathways and intracellular processes involved in the progression of hepatic cystogenesis is beneficial for PLD. Many of these targets have been evaluated in preclinical and clinical trials. In this review, we discuss the genetic, molecular, and cellular mechanisms of PLD and clinical and preclinical treatment strategies. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

DOI: https://doi.org/10.1146/annurev-pathol-042320-121247
Andrologia. 2021 Nov 05. e14273

Genetic testing, ultrasonography and preimplantation genetic testing of men with autosomal dominant polycystic kidney disease in Hunan, China.

Weina Li, Gang Liu, Xingguo Zhao, Yichang Lu, Huanzhu Li, Huan Zhang, Ge Lin.

  The present study identified novel mutations in polycystic kidney disease (PKD) genes in China, determined the prevalence of cysts in the genital tract and accessory gonad in autosomal dominant PKD (ADPKD) patients, correlated these genes with ADPKD and male infertility and investigated whether male infertility associated with ADPKD affected the clinical outcomes in a preimplantation genetic testing (PGT) cycle cohort. This study was a cross-sectional study. Twenty-four unrelated men with ADPKD recruited from the Reproductive and Genetic Hospital of CITIC-Xiangya in China were investigated between January 2019 and December 2020. A total of 24 variations were identified in 22 patients, including 23, 1 and 0 variations in PKD1, PKD2 and GANAB, respectively. Genital tract and accessory gonadal cysts were significant dependent variables for male infertility. A diagnosis was made in 87.04% (94/108) and 51.85% (56/108) of the embryos for ADPKD and PGT-A respectively. Clinical pregnancy reached 72.73% per embryo transfer and 84.21% per patient. We identified a group of novel mutations in PKD genes, which enriches the PKD mutation spectrum. Although genital tract and accessory gonadal cysts greatly influence the fertility of men with ADPKD, they have minimal clinical consequences on pregnancy by intracytoplasmic sperm injection (ICSI) and PGT.

Keywords:  ADPKD; PGT; genetic testing; ultrasonography

DOI:  https://doi.org/10.1111/and.14273
Eur Rev Med Pharmacol Sci. 2021 Oct;pii: 27005. [Epub ahead of print]25(20): 6333-6338

Screening of QTc interval and global autonomic activity in autosomal dominant polycystic kidney disease and atherosclerotic renal artery stenosis hypertensive patients.

S Lai, A M Perrotta, D Bagordo, S Mazzaferro, P Menè, A Gigante, F Tinti, A Galani, R Cianci.

OBJECTIVE: Arterial hypertension (AH) represents a major risk factor for cardiovascular disease and is associated to several complications, such as prolonged corrected QT (QTc) interval and impaired heart rate variability (HRV). Secondary causes of AH include autosomal dominant polycystic kidney disease (ADPKD) and atherosclerotic renal artery stenosis (ARAS), both known to be related to arrhythmic risk and autonomic imbalance. The aim of the study is to evaluate whether global autonomic activity and QTc interval differently affect ADPKD and ARAS hypertensive patients.
PATIENTS AND METHODS: An observational study was performed on 59 patients: 16 ADPKD patients and 19 diagnosed with ARAS, compared to 24 healthy controls (HC). All patients underwent clinical evaluation, biochemical lab tests, 24-hour electrocardiogram (ECG) and renal Doppler ultrasound. HRV was assessed through the analysis of 24-hour ECG to detect standard deviation of normal-to-normal RR intervals (SDNN). QTc interval was defined as prolonged when > 440 msec.
RESULTS: SDNN was significantly lower in ADPKD and ARAS patients than HC (p < 0.0001) and no significant differences were found between ADPKD and ARAS patients (p > 0.05). QTc was found significantly higher in ARAS patients than HC (p = 0.001) and in ARAS patients than ADPKD patients (p = 0.004).
CONCLUSIONS: The pathogenesis of hypertension in ADPKD and ARAS patients is related to the activation of the renin angiotensin aldosterone system (RAAS). In ADPKD, cyst enlargement leads to kidney ischemia and renin release, associated to endothelial dysfunction, low nitric oxide and sympathetic tone activation. Differently, reduction in renal perfusion pressure activates RAAS and renal adrenergic nerves in ARAS patients. We can speculate that prolonged QTc interval is more present in ARAS vs. ADPKD hypertensive patients due to a greater activation of RAAS. We suggest adding 24-hour HRV evaluation in association with traditional risk factors in course of ADPKD and ARAS hypertension to better stratify cardiovascular risk in these groups of patients.

DOI: https://doi.org/10.26355/eurrev_202110_27005
Nat Genet. 2021 Nov 04.

Reversing polycystic kidney disease.

Alessandra Boletta.

DOI: https://doi.org/10.1038/s41588-021-00963-3
Curr Biol. 2021 Oct 27. pii: S0960-9822(21)01416-0. [Epub ahead of print]

xbx-4, a homolog of the Joubert syndrome gene FAM149B1, acts via the CCRK and RCK kinase cascade to regulate cilia morphology.

Ashish K Maurya, Piali Sengupta.

  Primary cilia are microtubule (MT)-based organelles that mediate sensory functions in multiple cell types. Disruption of cilia structure or function leads to a diverse collection of diseases termed ciliopathies.1-3 The highly conserved CCRK and RCK kinases (ICK/MOK/MAK) negatively regulate cilia length and structure in Chlamydomonas, C. elegans, and mammalian cells.4-10 How the activity of this kinase cascade is tuned to precisely regulate cilia architecture is unclear. Mutations in the Domain of Unknown Function 3719 (DUF3719)-containing protein FAM149B1 have recently been shown to elongate cilia via unknown mechanisms and result in the ciliopathy Joubert syndrome.11 Here we identify XBX-4, a DUF3719-containing protein related to human FAM149B1, as a regulator of the DYF-18 CCRK and DYF-5 MAK kinase pathway in C. elegans. As in dyf-18 and dyf-5 mutants,10 sensory neuron cilia are elongated in xbx-4 mutants and exhibit stabilized axonemal MTs. XBX-4 promotes DYF-18 CCRK function to regulate localization and function of DYF-5 MAK. We find that Joubert syndrome-associated mutations in the XBX-4 DUF3719 domain also elongate cilia in C. elegans. Our results identify a new metazoan-specific regulator of this highly conserved kinase pathway and suggest that FAM149B1 may similarly act via the CCRK/RCK kinase pathway to regulate ciliary homeostasis in humans.

Keywords:  C. elegans; CCRK/RCK; DUF3719; FAM149B1; Joubert syndrome; cilia; xbx-4

DOI:  https://doi.org/10.1016/j.cub.2021.10.027
Can J Kidney Health Dis. 2021 ;8 20543581211055001

Mainstreaming Genetic Testing for Adult Patients With Autosomal Dominant Polycystic Kidney Disease.

Mark D Elliott, Leslie C James, Emily L Simms, Priyana Sharma, Louis P Girard, Kim Cheema, Meghan J Elliott, Julie L Lauzon, Justin Chun.

   Purpose: Genetic testing results are currently obtained approximately 1 year after referral to a medical genetics team for autosomal dominant polycystic kidney disease (ADPKD). We evaluated a mainstream genetic testing (MGT) pathway whereby the nephrology team provided pre-test counseling and selection of patients with suspected ADPKD for genetic testing prior to direct patient interaction by a medical geneticist.
Sources of information: A multidisciplinary team of nephrologists, genetic counselors, and medical geneticists developed an MGT pathway for ADPKD using current testing criteria for adult patient with suspected ADPKD and literature from MGT in oncology.
Methods: An MGT pathway was assessed using a prospective cohort and compared to a retrospective cohort of 56 patients with ADPKD who received genetic testing using the standard, traditional pathway prior to implementing the MGT for ADPKD. The mainstream pathway was evaluated using time to diagnosis, diagnostic yield, and a patient survey to assess patient perceptions of the MGT pathway.
Key findings: We assessed 26 patients with ADPKD using the MGT and 18 underwent genetic testing with return of results. Of them, 52 patients had data available for analysis in the traditional control cohort. The time for return of results using our MGT pathway was significantly shorter with a median time to results of 6 months compared to 12 months for the traditional pathway. We identified causative variants in 61% of patients, variants of uncertain significance in 28%, and 10% had negative testing which is in line with expectations from the literature. The patient surveys showed high satisfaction rates with the MGT pathway.
Limitations: This report is an evaluation of a new genetic testing pathway restricted to a single, publicly funded health care center. The MGT pathway involved a prospective collection of a limited number of patients with ADPKD with comparison to a retrospective cohort of patients with ADPKD evaluated by standard testing.
Implications: A MGT pathway using clearly defined criteria and commercially available gene panels for ADPKD can be successfully implemented in a publicly funded health care system to reduce the time required to obtain genetic results.

Keywords:  autosomal dominant polycystic kidney disease (ADPKD); chronic kidney disease (CKD); genetic testing; kidney failure; mainstream; medical genetics; next generation sequencing (NGS)

DOI:  https://doi.org/10.1177/20543581211055001
Sci Rep. 2021 Nov 04. 11(1): 21677

Early childhood height-adjusted total kidney volume as a risk marker of kidney survival in ARPKD.

ARegPKD Consortium

Autosomal recessive polycystic kidney disease (ARPKD) is characterized by bilateral fibrocystic changes resulting in pronounced kidney enlargement. Impairment of kidney function is highly variable and widely available prognostic markers are urgently needed as a base for clinical decision-making and future clinical trials. In this observational study we analyzed the longitudinal development of sonographic kidney measurements in a cohort of 456 ARPKD patients from the international registry study ARegPKD. We furthermore evaluated correlations of sonomorphometric findings and functional kidney disease with the aim to describe the natural disease course and to identify potential prognostic markers. Kidney pole-to-pole (PTP) length and estimated total kidney volume (eTKV) increase with growth throughout childhood and adolescence despite individual variability. Height-adjusted PTP length decreases over time, but such a trend cannot be seen for height-adjusted eTKV (haeTKV) where we even observed a slight mean linear increase of 4.5 ml/m per year during childhood and adolescence for the overall cohort. Patients with two null PKHD1 variants had larger first documented haeTKV values than children with missense variants (median (IQR) haeTKV 793 (450-1098) ml/m in Null/null, 403 (260-538) ml/m in Null/mis, 230 (169-357) ml/m in Mis/mis). In the overall cohort, estimated glomerular filtration rate decreases with increasing haeTKV (median (IQR) haeTKV 210 (150-267) ml/m in CKD stage 1, 472 (266-880) ml/m in stage 5 without kidney replacement therapy). Strikingly, there is a clear correlation between haeTKV in the first eighteen months of life and kidney survival in childhood and adolescence with ten-year kidney survival rates ranging from 20% in patients of the highest to 94% in the lowest quartile. Early childhood haeTKV may become an easily obtainable prognostic marker of kidney disease in ARPKD, e.g. for the identification of patients for clinical studies.

DOI: https://doi.org/10.1038/s41598-021-00523-z
Cell Tissue Res. 2021 Nov 05.

Vangl2 participates in the primary ciliary assembly under low fluid shear stress in hUVECs.

Xin Sheng, Shuanglin Gao, Yan Sheng, Xiadan Xie, Junhua Wang, Yan He.

  The pattern of blood fluid shear stress (FSS) is considered the main factor that affects ciliogenesis in human umbilical vein endothelial cells (hUVECs), the underlying mechanism is unclear. Microfluidic chamber experiments were carried out to load hUVECs with low fluid shear stress (LSS, 0.1 dynes/cm2) or high fluid shear stress (HSS, 15 dynes/cm2). Van Gogh2 (Vangl2), a core protein in the planar cell polarity (PCP) pathway, was silenced and overexpressed in hUVECs. Immunofluorescence analysis showed that primary cilia assemble under LSS while disassembling under HSS. Vangl2 expression was consistent with cilia assembly, and its localization showed a polar distribution under LSS. Furthermore, the average number of ciliated cells and primary cilia length were increased in the Vangl2 overexpressing cell lines (the OE group) but decreased in the Vangl2 silenced cell lines (the SH group). When these cells were loaded with different FSS, more ciliated cells with longest primary cilia were observed in the LSS loaded OE group compared with those in the other groups. Immunoprecipitation showed that the interaction between Bardet-Biedl syndrome 8 (BBS8) and Vangl2 was enhanced following LSS loading compared to that under HSS. However, the interactions between phosphorylated dishevelled segment polarity protein 2 (pDvl2), kinesin family member 2a (Kif2a), and polo-like kinase 1 (Plk1) and Vangl2 were restrained following LSS loading. Overall, the results indicated that Vangl2 played a significant role during LSS-induced primary cilia assembly by recruiting BBS to promote the apical docking of basal bodies and by restraining Dvl2 phosphorylation from reducing primary cilia disassembly.

Keywords:  Basal body; Ciliogenesis; Fluid shear stress; Primary cilia; Vangl2

DOI:  https://doi.org/10.1007/s00441-021-03546-0
Sci Rep. 2021 Nov 02. 11(1): 21473

Hypoxia induces stress fiber formation in adipocytes in the early stage of obesity.

Golnaz Anvari, Evangelia Bellas.

In obese adipose tissue (AT), hypertrophic expansion of adipocytes is not matched by new vessel formation, leading to AT hypoxia. As a result, hypoxia inducible factor-1⍺ (HIF-1⍺) accumulates in adipocytes inducing a transcriptional program that upregulates profibrotic genes and biosynthetic enzymes such as lysyl oxidase (LOX) synthesis. This excess synthesis and crosslinking of extracellular matrix (ECM) components cause AT fibrosis. Although fibrosis is a hallmark of obese AT, the role of fibroblasts, cells known to regulate fibrosis in other fibrosis-prone tissues, is not well studied. Here we have developed an in vitro model of AT to study adipocyte-fibroblast crosstalk in a hypoxic environment. Further, this in vitro model was used to investigate the effect of hypoxia on adipocyte mechanical properties via ras homolog gene family member A (RhoA)/Rho-associated coiled-coil kinases (ROCK) signaling pathways. We confirmed that hypoxia creates a diseased phenotype by inhibiting adipocyte maturation and inducing actin stress fiber formation facilitated by myocardin-related transcription factor A (MRTF-A/MKL1) nuclear translocation. This work presents new potential therapeutic targets for obesity by improving adipocyte maturation and limiting mechanical stress in obese AT.

DOI: https://doi.org/10.1038/s41598-021-00335-1
Nephrology (Carlton). 2021 Nov 01.

Will advances in functional renal MRI translate to the nephrology clinic?

Alastair J Rankin, Kaitlin Mayne, Sarah Allwood-Spiers, Pauline Hall Barrientos, Giles Roditi, Keith A Gillis, Patrick B Mark.

Characterizing structural and tissue abnormalities of the kidney is fundamental to understanding kidney disease. Functional multi-parametric renal magnetic resonance imaging (MRI) is a noninvasive imaging strategy whereby several sequences are employed within a single session to quantify renal perfusion, tissue oxygenation, fibrosis, inflammation, and oedema without using ionizing radiation. In this review, we discuss evidence surrounding its use in several clinical settings including acute kidney injury, chronic kidney disease, hypertension, polycystic kidney disease and around renal transplantation. Kidney size on MRI is already a validated measure for making therapeutic decisions in the setting of polycystic kidney disease. Functional MRI sequences, T1 mapping and apparent diffusion coefficient, can non-invasively quantify interstitial fibrosis and so may have a near-future role in the nephrology clinic to stratify the risk of progressive chronic kidney disease or transplant dysfunction. Beyond this, multi-parametric MRI may be utilised diagnostically, for example differentiating inflammatory versus ischaemic causes of renal dysfunction, but this remains to be proven. Changes in MRI properties of kidney parenchyma may be useful surrogate markers to use as end points in clinical trials to assess if drugs prevent renal fibrosis or alter kidney perfusion. Large, multi-centre studies of functional renal MRI are ongoing which aim to provide definitive answers as to its role in the management of patients with renal dysfunction. This article is protected by copyright. All rights reserved.

DOI: https://doi.org/10.1111/nep.13985
J Cell Biol. 2022 Jan 03. pii: e202010178. [Epub ahead of print]221(1):

WDR60-mediated dynein-2 loading into cilia powers retrograde IFT and transition zone crossing.

Ana R G De-Castro, Diogo R M Rodrigues, Maria J G De-Castro, Neide Vieira, Cármen Vieira, Ana X Carvalho, Reto Gassmann, Carla M C Abreu, Tiago J Dantas.

The dynein-2 motor complex drives retrograde intraflagellar transport (IFT), playing a pivotal role in the assembly and functions of cilia. However, the mechanisms that regulate dynein-2 motility remain poorly understood. Here, we identify the Caenorhabditis elegans WDR60 homologue, WDR-60, and dissect the roles of this intermediate chain using genome editing and live imaging of endogenous dynein-2/IFT components. We find that loss of WDR-60 impairs dynein-2 recruitment to cilia and its incorporation onto anterograde IFT trains, reducing retrograde motor availability at the ciliary tip. Consistent with this, we show that fewer dynein-2 motors power WDR-60-deficient retrograde IFT trains, which move at reduced velocities and fail to exit cilia, accumulating on the distal side of the transition zone. Remarkably, disrupting the transition zone's NPHP module almost fully restores ciliary exit of underpowered retrograde trains in wdr-60 mutants. This work establishes WDR-60 as a major contributor to IFT, and the NPHP module as a roadblock to dynein-2 passage through the transition zone.

DOI: https://doi.org/10.1083/jcb.202010178
Eur J Hum Genet. 2021 Nov 01.

Identification of a novel variant of the ciliopathic gene FUZZY associated with craniosynostosis.

William B Barrell, Hadeel Adel Al-Lami, Jacqueline A C Goos, Sigrid M A Swagemakers, Marieke van Dooren, Elena Torban, Peter J van der Spek, Irene M J Mathijssen, Karen J Liu.

Craniosynostosis is a birth defect occurring in approximately one in 2000 live births, where premature fusion of the cranial bones inhibits growth of the skull during critical periods of brain development. The resulting changes in skull shape can lead to compression of the brain, causing severe complications. While we have some understanding of the molecular pathology of craniosynostosis, a large proportion of cases are of unknown genetic aetiology. Based on studies in mouse, we previously proposed that the ciliopathy gene Fuz should be considered a candidate craniosynostosis gene. Here, we report a novel variant of FUZ (c.851 G > C, p.(Arg284Pro)) found in monozygotic twins presenting with craniosynostosis. To investigate whether Fuz has a direct role in regulating osteogenic fate and mineralisation, we cultured primary osteoblasts and mouse embryonic fibroblasts (MEFs) from Fuz mutant mice. Loss of Fuz resulted in increased osteoblastic mineralisation. This suggests that FUZ protein normally acts as a negative regulator of osteogenesis. We then used Fuz mutant MEFs, which lose functional primary cilia, to test whether the FUZ p.(Arg284Pro) variant could restore FUZ function during ciliogenesis. We found that expression of the FUZ p.(Arg284Pro) variant was sufficient to partially restore cilia numbers, but did not mediate a comparable response to Hedgehog pathway activation. Together, this suggests the osteogenic effects of FUZ p.(Arg284Pro) do not depend upon initiation of ciliogenesis.

DOI: https://doi.org/10.1038/s41431-021-00988-6
Elife. 2021 Nov 04. pii: e69786. [Epub ahead of print]10

A WDR35-dependent coat protein complex transports ciliary membrane cargo vesicles to cilia.

Tooba Quidwai, Jiaolong Wang, Emma A Hall, Narcis A Petriman, Weihua Leng, Petra Kiesel, Jonathan N Wells, Laura C Murphy, Margaret A Keighren, Joseph A Marsh, Esben Lorentzen, Gaia Pigino, Pleasantine Mill.

  Intraflagellar transport (IFT) is a highly conserved mechanism for motor-driven transport of cargo within cilia, but how this cargo is selectively transported to cilia is unclear. WDR35/IFT121 is a component of the IFT-A complex best known for its role in ciliary retrograde transport. In the absence of WDR35, small mutant cilia form but fail to enrich in diverse classes of ciliary membrane proteins. In Wdr35 mouse mutants, the non-core IFT-A components are degraded and core components accumulate at the ciliary base. We reveal deep sequence homology of WDR35 and other IFT-A subunits to α and ß' COPI coatomer subunits, and demonstrate an accumulation of 'coat-less' vesicles which fail to fuse with Wdr35 mutant cilia. We determine that recombinant non-core IFT-As can bind directly to lipids and provide the first in-situ evidence of a novel coat function for WDR35, likely with other IFT-A proteins, in delivering ciliary membrane cargo necessary for cilia elongation.

Keywords:  cell biology; chlamydomonas reinhardtii; mouse

DOI:  https://doi.org/10.7554/eLife.69786
Hum Mol Genet. 2021 Nov 05. pii: ddab322. [Epub ahead of print]

Biallelic ANKS6 mutations cause late onset ciliopathy with chronic kidney disease through YAP dysregulation.

Hannah Schwarz, Bernt Popp, Rannar Airik, Nasrin Torabi, Karl X Knaup, Johanna Stoeckert, Thorsten Wiech, Kerstin Amann, André Reis, Mario Schiffer, Michael S Wiesener, Markus Schueler.

Nephronophthisis-related ciliopathies (NPHP-RC) comprises a group of inherited kidney diseases, caused by mutations in genes encoding proteins localizing to primary cilia. NPHP-RC represent the one of the most frequent monogenic causes of renal failure within the first three decades of life, but its molecular disease mechanisms remains unclear. Here, we identified biallelic ANKS6 mutations in two affected siblings with late onset chronic kidney disease by whole exome sequencing. We employed patient derived fibroblasts generating an in vitro model to study the precise biological impact of distinct human ANKS6 mutations, completed by immunohistochemistry studies on renal biopsy samples. Functional studies using patient derived cells showed an impaired integrity of the ciliary Inversin compartment with reduced cilia length. Further analyses demonstrated that ANKS6 deficiency leads to a dysregulation of Hippo-signaling through nuclear YAP imbalance, and disrupted ciliary localization of YAP. Additionally an altered transcriptional activity of canonical Wnt target genes and altered expression of non-phosphorylated (active) β-catenin and phosphorylated GSK3β were observed. Upon ciliation ANKS6 deficiency revealed a deranged subcellular localization and expression of components of the endocytic recycling compartment. Our results demonstrate that ANKS6 plays a key role in regulating the Hippo pathway and ANKS6 deficiency is linked to dysregulation of signaling pathways. Our study provides molecular clues in understanding pathophysiological mechanisms of NPHP-RC and may offer new therapeutic targets.

DOI: https://doi.org/10.1093/hmg/ddab322
FASEB J. 2021 Dec;35(12): e22012

Paxillin controls actin stress fiber formation and migration of vascular smooth muscle cells by directly binding to the active Fyn.

Ying Zhang, Hiroko Kishi, Tomoka Morita, Sei Kobayashi.

  Rho-kinase (ROK)-mediated migration of vascular smooth muscle cells plays a crucial role in cardiovascular diseases. Previously we demonstrated Fyn tyrosine kinase as an upstream molecule of ROK to mediate actin stress fiber formation that plays an important role in cell migration, but the molecular mechanism between the two kinases was unclear. To discover a novel signaling molecule that exists between Fyn and ROK, we identified paxillin acting downstream of the active Fyn by combined use of pulldown assay and mass spectrometry. Immunofluorescence staining confirmed co-localization of Fyn and paxillin at the ends of actin stress fibers in human coronary artery smooth muscle cells (CASMCs). Surface plasmon resonance assay demonstrated direct binding between constitutively active Fyn (CA-Fyn) and N-terminus of paxillin (N-pax). The sphingosylphosphorylcholine (SPC)-induced ROK activation, actin stress fiber formation and cell migration were inhibited by paxillin knockdown, which were rescued by full-length paxillin (FL-pax) but not N-pax. N-pax co-localized with CA-Fyn at the cytosol and overexpression of N-pax inhibited the SPC-induced actin stress fiber formation and cell migration, indicating that the direct binding of FL-pax and CA-Fyn at the ends of actin stress fibers is essential for the ROK-mediated actin stress fiber formation and cell migration. Paxillin, as a novel signalling molecule, mediates the SPC-induced actin stress fiber formation and migration in human CASMCs via the Fyn/paxillin/ROK signalling pathway by direct binding of active Fyn.

Keywords:  Fyn; Rho-kinase; actin stress fiber; migration; paxillin

DOI:  https://doi.org/10.1096/fj.202101035RR