bims-bicyki Biomed News
on Bicaudal-C1 and interactors in cystic kidney disease
Issue of 2021–02–14
eightteen papers selected by
Céline Gagnieux, École Polytechnique Fédérale de Lausanne
  1. Use of the Urine-to-Plasma Urea Ratio to Predict ADPKD Progression.
  2. Adult Inactivation of the Recessive Polycystic Kidney Disease Gene Causes Polycystic Liver Disease.
  3. A practical guide for the management of acute abdominal pain with fever in patients with autosomal dominant polycystic kidney disease.
  4. Polycystic liver disease genes: practical considerations for genetic testing.
  5. Up-regulation of DNA Damage Response Signaling in Autosomal Dominant Polycystic Kidney Disease.
  6. mtor Haploinsufficiency Ameliorates Renal Cysts and Cilia Abnormality in Adult Zebrafish tmem67 Mutants.
  7. Bilateral Nephrectomy in Patients with Autosomal Dominant Polycystic Kidney Disease and End-Stage Chronic Renal Failure.
  8. Autosomal Recessive Polycystic Kidney Disease-The Clinical Aspects and Diagnostic Challenges.
  9. RAB19 Directs Cortical Remodeling and Membrane Growth for Primary Ciliogenesis.
  10. Rho-Kinase 1/2 Inhibition Prevents Transforming Growth Factor-β-Induced Effects on Pulmonary Remodeling and Repair.
  11. A centriole's subdistal appendages: contributions to cell division, ciliogenesis and differentiation.
  12. Protein Kinase A-Mediated Septin7 Phosphorylation Disrupts Septin Filaments and Ciliogenesis.
  13. Tolvaptan-induced remission of primary palmar hyperhidrosis in a patient with ADPKD: a serendipitous finding.
  14. Autophagy-dependent regulation of skeletal muscle regeneration and strength by a RHOGEF.
  15. Association of a novel PKHD1 mutation in a family with autosomal dominant polycystic liver disease.
  16. Targeted Intestinal Deletion of Rho Guanine Nucleotide Exchange Factor 7, βPIX, Impairs Enterocyte Proliferation, Villus Maturation and Mucosal Defenses in Mice.
  17. Propofol relieves inflammation in MIRI rats by inhibiting Rho/Rock signaling pathway.
  18. Actin-granule formation is an additional step in cardiac myofibroblast differentiation.
  1. Clin J Am Soc Nephrol. 2021 Feb 08. 16(2): 204-212
    Use of the Urine-to-Plasma Urea Ratio to Predict ADPKD Progression.
    DIPAK Consortium
       BACKGROUND AND OBJECTIVES: Predicting disease progression in patients with autosomal dominant polycystic kidney disease (ADPKD) poses a challenge, especially in early-stage disease when kidney function is not yet affected. Ongoing growth of cysts causes maximal urine-concentrating capacity to decrease from early on. We therefore hypothesized that the urine-to-plasma urea ratio, as a reflection of the urine-concentrating capacity, can be used as a marker to predict ADPKD progression.
    DESIGN: The urine-to-plasma urea ratio was calculated by dividing concentrations of early morning fasting spot urine urea by plasma urea. First, this ratio was validated as surrogate marker in 30 patients with ADPKD who underwent a prolonged water deprivation test. Thereafter, association with kidney outcome was evaluated in 583 patients with ADPKD with a broad range of kidney function. Multivariable mixed-model regression was used to assess association with eGFR slope, and logarithmic regression to identify patients with rapidly progressive disease, using a cutoff of -3.0 ml/min per 1.73 m2 per year. The urine-to-plasma urea ratio was compared with established predictors, namely, sex, age, baseline eGFR, Mayo Clinic height-adjusted total kidney volume class, and PKD gene mutation.
    RESULTS: The maximal urine-concentrating capacity and urine-to-plasma urea ratio correlated strongly (R=0.90; P<0.001). Next, the urine-to-plasma urea ratio was significantly associated with rate of eGFR decline during a median follow-up of 4.0 (interquartile range, 2.6-5.0) years, both crude and after correction for established predictors (β=0.58; P=0.02). The odds ratio of rapidly progressive disease was 1.35 (95% confidence interval, 1.19 to 1.52; P<0.001) for every 10 units decrease in urine-to-plasma urea ratio, with adjustment for predictors. A combined risk score of the urine-to-plasma urea ratio, Mayo Clinic height-adjusted total kidney volume class, and PKD mutation predicted rapidly progressive disease better than each of the predictors separately.
    CONCLUSIONS: The urine-to-plasma urea ratio, which is calculated from routine laboratory measurements, predicts disease progression in ADPKD in addition to other risk markers.
    PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2021_01_27_CJN10470620_final.mp3.
    Keywords:  ADPKD; autosomal dominant polycystic kidney disease; renal function decline; urea; urine-to-plasma urea ratio
    DOI:  https://doi.org/10.2215/CJN.10470620
  2. Kidney360. 2020 Oct;1(10): 1068-1076
    Adult Inactivation of the Recessive Polycystic Kidney Disease Gene Causes Polycystic Liver Disease.
    Whitney Besse, Charlotte Roosendaal, Luigi Tuccillo, Sounak Ghosh Roy, Anna-Rachel Gallagher, Stefan Somlo.
       Background: A major difference between autosomal recessive polycystic kidney disease (ARPKD) and autosomal dominant polycystic kidney disease (ADPKD) lies in the pattern of inheritance, and the resultant timing and focality of cyst formation. In both diseases, cysts form in the kidney and liver as a consequence of the cellular recessive genotype of the respective disease gene, but this occurs by germline inheritance in ARPKD and somatic second hit mutations to the one normal allele in ADPKD. The fibrocystic liver phenotype in ARPKD is attributed to abnormal ductal plate formation because of the absence of PKHD1 expression during embryogenesis and organ development. The finding of polycystic liver disease in a subset of adult PKHD1 heterozygous carriers raises the question of whether somatic second hit mutations in PKHD1 in adults may also result in bile duct-derived cyst formation.
    Methods: We used an adult-inducible Pkhd1 mouse model to examine whether Pkhd1 has a functional role in maintaining bile duct homeostasis after normal liver development.
    Results: Inactivation of Pkhd1 beginning at 4 weeks of age resulted in a polycystic liver phenotype with minimal fibrosis at 17 weeks. Increased biliary epithelium, which lines these liver cysts, was most pronounced in female mice. We assessed genetic interaction of this phenotype with either reduced or increased copies of Pkd1, and found no significant effects on the Pkhd1 phenotype in the liver or kidney from altered Pkd1 expression.
    Conclusions: Somatic adult inactivation of Pkhd1 results in a polycystic liver phenotype. Pkhd1 is a required gene in adulthood for biliary structural homeostasis independent of Pkd1. This suggests that PKHD1 heterozygous carrier patients can develop liver cysts after somatic mutations in their normal copy of PKHD1.
    DOI:  https://doi.org/10.34067/kid.0002522020
  3. Nephrol Dial Transplant. 2021 Feb 11. pii: gfab040. [Epub ahead of print]
    A practical guide for the management of acute abdominal pain with fever in patients with autosomal dominant polycystic kidney disease.
    François Jouret, Marie C Hogan, Fouad T Chebib.
      Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the development of numerous renal cysts leading to kidney enlargement and chronic kidney disease. Extra-renal manifestations, including polycystic liver disease and connective tissue defects, are frequently observed in ADPKD. Acute cyst complications, i.e. hemorrhage and infection, represent rare but severe conditions of ADPKD. The distinction between cystic versus non-cystic abdominal complications is often problematic. Here, we propose a practical guide for the diagnostic and therapeutic management of an "acute abdominal pain with fever" in patients with ADPKD.
    DOI:  https://doi.org/10.1093/ndt/gfab040
  4. Eur J Med Genet. 2021 Feb 05. pii: S1769-7212(21)00026-4. [Epub ahead of print] 104160
    Polycystic liver disease genes: practical considerations for genetic testing.
    Melissa M Boerrigter, Ernie M H F Bongers, Dorien Lugtenberg, Frederik Nevens, Joost P H Drenth.
      The development of a polycystic liver is a characteristic of the monogenic disorders: autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), and autosomal dominant polycystic liver disease (ADPLD). Respectively two and one genes mainly cause ADPKD and ARPKD. In contrast, ADPLD is caused by at least six different genes which combined do not even explain the disease development in over half of the ADPLD population. Genetic testing is mainly performed to confirm the likelihood of developing PKD and if renal therapy is essential. However, pure ADPLD patients are frequently not genetically screened as knowledge about the genotype-phenotype correlation is currently limited. This paper will clarify the essence of genetic testing in ADPLD patients.
    Keywords:  ADPLD; clinical value; genetic testing; polycystic liver
    DOI:  https://doi.org/10.1016/j.ejmg.2021.104160
  5. Am J Pathol. 2021 Feb 04. pii: S0002-9440(21)00042-0. [Epub ahead of print]
    Up-regulation of DNA Damage Response Signaling in Autosomal Dominant Polycystic Kidney Disease.
    Jennifer Q J Zhang, Sayanthooran Saravanabavan, Ashley N Chandra, Alexandra Munt, Annette T Y Wong, Peter C Harris, David C H Harris, Paul McKenzie, Yiping Wang, Gopala K Rangan.
      DNA damage and alterations in DNA Damage Response (DDR) signaling could be one of the molecular mechanisms mediating focal kidney cyst formation in autosomal dominant polycystic kidney disease (ADPKD). The aim of this study was to test the hypothesis that markers of DNA damage and DDR signaling are increased in human and experimental ADPKD. In the human ADPKD transcriptome, the number of upregulated DDR-related genes was increased by 16.6-fold compared to normal kidney, and by 2.5-fold in cystic compared to minimally cystic tissue (P<0.0001). In end-stage human ADPKD tissue, gamma (γ)-H2AX, phosphorylated Ataxia Telangiectasia and Rad3-related (p-ATR) and AT Mutated (p-ATM) localized to cystic kidney epithelial cells. In vitro, p-ATR and p-ATM were also constitutively increased in human ADPKD tubular cells (WT 9-7, 9-12) compared to control (HK-2). Additionally, extrinsic oxidative DNA damage by H2O2 augmented γ-H2AX and cell survival in human ADPKD cells, and exacerbated cyst growth in the 3D MDCK cyst model. In contrast, DDR-related gene expression was only transiently increased on postnatal day 0 in Pkd1RC/RC mice, and not altered at later timepoints up to 12 months of age. In conclusion, DDR signaling is dysregulated in human ADPKD and during the early phases of murine ADPKD. The constitutive expression of the DDR pathway in ADPKD may promote survival of PKD1-mutated cells and contribute to kidney cyst growth.
    Keywords:  DNA damage; DNA damage response; polycystic kidney disease
    DOI:  https://doi.org/10.1016/j.ajpath.2021.01.011
  6. J Am Soc Nephrol. 2021 Feb 11. pii: ASN.2020070991. [Epub ahead of print]
    mtor Haploinsufficiency Ameliorates Renal Cysts and Cilia Abnormality in Adult Zebrafish tmem67 Mutants.
    Ping Zhu, Qi Qiu, Peter C Harris, Xiaolei Xu, Xueying Lin.
       BACKGROUND: Although zebrafish embryos have been used to study ciliogenesis and model polycystic kidney disease (PKD), adult zebrafish remain unexplored.
    METHODS: Transcription activator-like effector nucleases (TALEN) technology was used to generate mutant for tmem67, the homolog of the mammalian causative gene for Meckel syndrome type 3 (MKS3). Classic 2D and optical-clearing 3D imaging of an isolated adult zebrafish kidney were used to examine cystic and ciliary phenotypes. A hypomorphic mtor strain or rapamycin was used to inhibit mTOR activity.
    RESULTS: Adult tmem67 zebrafish developed progressive mesonephric cysts that share conserved features of mammalian cystogenesis, including a switch of cyst origin with age and an increase in proliferation of cyst-lining epithelial cells. The mutants had shorter and fewer distal single cilia and greater numbers of multiciliated cells (MCCs). Absence of a single cilium preceded cystogenesis, and expansion of MCCs occurred after pronephric cyst formation and was inversely correlated with the severity of renal cysts in young adult zebrafish, suggesting a primary defect and an adaptive action, respectively. Finally, the mutants exhibited hyperactive mTOR signaling. mTOR inhibition ameliorated renal cysts in both the embryonic and adult zebrafish models; however, it only rescued ciliary abnormalities in the adult mutants.
    CONCLUSIONS: Adult zebrafish tmem67 mutants offer a new vertebrate model for renal cystic diseases, in which cilia morphology can be analyzed at a single-nephron resolution and mTOR inhibition proves to be a candidate therapeutic strategy.
    Keywords:  genetics and development; molecular genetics; optical clearing; polycystic kidney disease
    DOI:  https://doi.org/10.1681/ASN.2020070991
  7. Nephron. 2021 Feb 05. 1-7
    Bilateral Nephrectomy in Patients with Autosomal Dominant Polycystic Kidney Disease and End-Stage Chronic Renal Failure.
    Alexander E Lubennikov, Nicolay V Petrovskii, German E Krupinov, Evgeniy M Shilov, Roman N Trushkin, Oleg N Kotenko, Petr V Glybochko.
       BACKGROUND: In patients with autosomal dominant polycystic kidney disease (ADPKD) and end-stage kidney disease, bilateral nephrectomy (BN) is currently performed predominantly via the laparoscopic approach. We analysed the results of BN depending on the approach and preoperative and perioperative factors.
    PATIENTS AND METHODS: This was a single-centre retrospective study carried out from April 2010 to March 2020, including a total of 142 patients presenting with ADPKD who were treated by BN. Of these, 108 patients meeting the inclusion criteria were selected to analyse the results. We compared therapeutic outcomes depending on the surgical approach (laparotomy or laparoscopy) and the type of the operation (emergent or elective).
    RESULTS: Of the 108 eligible patients, 36 (group I) underwent laparoscopic BN and the remaining 72 patients (group II) were subjected to midline laparotomy. Sixty-nine patients underwent elective surgery and 39 endured emergent operations. The most frequent indications (87 patients, 80.6%) for surgical treatment were urinary tract infection and infected cysts. The median length of hospital stay for group I and group II patients amounted to 8 days (IQR: 7.5-9) and 12.5 days (IQR: 9-16.5), respectively (p < 0.001). However, comparing the patients operated on electively, the actual difference in the length of hospital stay was inconsiderable: median 8 days (IQR: 7-9) in group I and 9 days (IQR: 9-11.5) in group II. The median duration of the operation was significantly (p < 0.001) longer in group I amounting to 217.5 min (IQR: 197.5-305) than in group II equalling 115 min (IQR: 107.5-145). The frequency of postoperative complications, lethal outcomes, and blood loss volume did not statistically significantly differ depending on the surgical approach. Only patients operated on emergency underwent releparotomy due to intraoperative large bowel injury. Lethal outcomes (n = 18, 16.7%) after surgery were observed only in emergent patients. Sepsis prior to surgery, systemic inflammation response syndrome (SIRS) with the CRP level above 173 mg/mL, prolonged preoperative antibacterial therapy, and undiagnosed large bowel injury were associated with a lethal outcome after BN.
    CONCLUSION: The results of open and laparoscopic BN in elective surgery were comparable. Emergency operations for infected renal cysts and SIRS were associated with increased incidence of large bowel injury and lethal outcomes.
    Keywords:  Autosomal dominant polycystic kidney disease; Bilateral nephrectomy; End-stage kidney disease
    DOI:  https://doi.org/10.1159/000513168
  8. J Pediatr Genet. 2021 Mar;10(1): 1-8
    Autosomal Recessive Polycystic Kidney Disease-The Clinical Aspects and Diagnostic Challenges.
    Dorota Wicher, Łukasz Obrycki, Irena Jankowska.
      Autosomal recessive polycystic kidney disease (ARPKD) is one of the most common ciliopathies with kidney (nephromegaly, hypertension, renal dysfunction) and liver involvement (congenital hepatic fibrosis, dilated bile ducts). Clinical features also include growth failure and neurocognitive impairment. Plurality of clinical aspects requires multidisciplinary approach to treatment and care of patients. Until recently, diagnosis was based on clinical criteria. Results of genetic testing show the molecular basis of polycystic kidneys disease is heterogeneous, and differential diagnosis is essential. The aim of the article is to discuss the role of genetic testing and its difficulties in diagnostics of ARPKD in children.
    Keywords:  autosomal recessive polycystic kidney disease; congenital hepatic fibrosis; next-generation sequencing
    DOI:  https://doi.org/10.1055/s-0040-1714701
  9. Dev Cell. 2021 Feb 08. pii: S1534-5807(20)30978-3. [Epub ahead of print]56(3): 325-340.e8
    RAB19 Directs Cortical Remodeling and Membrane Growth for Primary Ciliogenesis.
    Cayla E Jewett, Adam W J Soh, Carrie H Lin, Quanlong Lu, Ezra Lencer, Christopher J Westlake, Chad G Pearson, Rytis Prekeris.
      Primary cilia are sensory organelles that utilize the compartmentalization of membrane and cytoplasm to communicate signaling events, and yet, how the formation of a cilium is coordinated with reorganization of the cortical membrane and cytoskeleton is unclear. Using polarized epithelia, we find that cortical actin clearing and apical membrane partitioning occur where the centrosome resides at the cell surface prior to ciliation. RAB19, a previously uncharacterized RAB, associates with the RAB-GAP TBC1D4 and the HOPS-tethering complex to coordinate cortical clearing and ciliary membrane growth, which is essential for ciliogenesis. This RAB19-directed pathway is not exclusive to polarized epithelia, as RAB19 loss in nonpolarized cell types blocks ciliogenesis with a docked ciliary vesicle. Remarkably, inhibiting actomyosin contractility can substitute for the function of the RAB19 complex and restore ciliogenesis in knockout cells. Together, this work provides a mechanistic understanding behind a cytoskeletal clearing and membrane partitioning step required for ciliogenesis.
    Keywords:  Actin; HOPS complex; RAB; TBC1D4; apical polarity; centrosome; cilia
    DOI:  https://doi.org/10.1016/j.devcel.2020.12.003
  10. Front Pharmacol. 2020 ;11 609509
    Rho-Kinase 1/2 Inhibition Prevents Transforming Growth Factor-β-Induced Effects on Pulmonary Remodeling and Repair.
    Xinhui Wu, Vicky Verschut, Manon E Woest, John-Poul Ng-Blichfeldt, Ana Matias, Gino Villetti, Alessandro Accetta, Fabrizio Facchinetti, Reinoud Gosens, Loes E M Kistemaker.
      Transforming growth factor (TGF)-β-induced myofibroblast transformation and alterations in mesenchymal-epithelial interactions contribute to chronic lung diseases such as chronic obstructive pulmonary disease (COPD), asthma and pulmonary fibrosis. Rho-associated coiled-coil-forming protein kinase (ROCK) consists as two isoforms, ROCK1 and ROCK2, and both are playing critical roles in many cellular responses to injury. In this study, we aimed to elucidate the differential role of ROCK isoforms on TGF-β signaling in lung fibrosis and repair. For this purpose, we tested the effect of a non-selective ROCK 1 and 2 inhibitor (compound 31) and a selective ROCK2 inhibitor (compound A11) in inhibiting TGF-β-induced remodeling in lung fibroblasts and slices; and dysfunctional epithelial-progenitor interactions in lung organoids. Here, we demonstrated that the inhibition of ROCK1/2 with compound 31 represses TGF-β-driven actin remodeling as well as extracellular matrix deposition in lung fibroblasts and PCLS, whereas selective ROCK2 inhibition with compound A11 did not. Furthermore, the TGF-β induced inhibition of organoid formation was functionally restored in a concentration-dependent manner by both dual ROCK 1 and 2 inhibition and selective ROCK2 inhibition. We conclude that dual pharmacological inhibition of ROCK 1 and 2 counteracts TGF-β induced effects on remodeling and alveolar epithelial progenitor function, suggesting this to be a promising therapeutic approach for respiratory diseases associated with fibrosis and defective lung repair.
    Keywords:  TGFβ signaling; lung organoid; lung repair; pulmonary remodeling; rock inhibition
    DOI:  https://doi.org/10.3389/fphar.2020.609509
  11. Open Biol. 2021 Feb;11(2): 200399
    A centriole's subdistal appendages: contributions to cell division, ciliogenesis and differentiation.
    Nicole A Hall, Heidi Hehnly.
      The centrosome is a highly conserved structure composed of two centrioles surrounded by pericentriolar material. The mother, and inherently older, centriole has distal and subdistal appendages, whereas the daughter centriole is devoid of these appendage structures. Both appendages have been primarily linked to functions in cilia formation. However, subdistal appendages present with a variety of potential functions that include spindle placement, chromosome alignment, the final stage of cell division (abscission) and potentially cell differentiation. Subdistal appendages are particularly interesting in that they do not always display a conserved ninefold symmetry in appendage organization on the mother centriole across eukaryotic species, unlike distal appendages. In this review, we aim to differentiate both the morphology and role of the distal and subdistal appendages, with a particular focus on subdistal appendages.
    Keywords:  centrosome; cilia; ciliopathies; division; midbody; subdistal appendages
    DOI:  https://doi.org/10.1098/rsob.200399
  12. Cells. 2021 Feb 09. pii: 361. [Epub ahead of print]10(2):
    Protein Kinase A-Mediated Septin7 Phosphorylation Disrupts Septin Filaments and Ciliogenesis.
    Han-Yu Wang, Chun-Hsiang Lin, Yi-Ru Shen, Ting-Yu Chen, Chia-Yih Wang, Pao-Lin Kuo.
      Septins are GTP-binding proteins that form heteromeric filaments for proper cell growth and migration. Among the septins, septin7 (SEPT7) is an important component of all septin filaments. Here we show that protein kinase A (PKA) phosphorylates SEPT7 at Thr197, thus disrupting septin filament dynamics and ciliogenesis. The Thr197 residue of SEPT7, a PKA phosphorylating site, was conserved among different species. Treatment with cAMP or overexpression of PKA catalytic subunit (PKACA2) induced SEPT7 phosphorylation, followed by disruption of septin filament formation. Constitutive phosphorylation of SEPT7 at Thr197 reduced SEPT7‒SEPT7 interaction, but did not affect SEPT7‒SEPT6‒SEPT2 or SEPT4 interaction. Moreover, we noted that SEPT7 interacted with PKACA2 via its GTP-binding domain. Furthermore, PKA-mediated SEPT7 phosphorylation disrupted primary cilia formation. Thus, our data uncover the novel biological function of SEPT7 phosphorylation in septin filament polymerization and primary cilia formation.
    Keywords:  catalytic subunit; primary cilium; protein kinase A; septin filament; septin7
    DOI:  https://doi.org/10.3390/cells10020361
  13. J Nephrol. 2021 Feb 08.
    Tolvaptan-induced remission of primary palmar hyperhidrosis in a patient with ADPKD: a serendipitous finding.
    E Cuka, M Vespa, G Joli, P Manunta, T M Sciarrone Alibrandi.
      A 37-year old man had suffered palmar hyperhidrosis since he was fifteen years old. In the last year, he has been treated with tolvaptan for autosomic polycystic kidney disease (ADPKD). The start of tolvaptan therapy was associated with a complete resolution of palmar hyperhidrosis and a sensation of relaxation. During the year on which the patient took tolvaptan, he had to suspend the drug twice. The suspension of tolvaptan was associated with the reappearance of palmar hyperhidrosis followed by sudden remission after the drug reintroduction. Palmar sweating also known as 'emotional sweating' is not related to thermoregulation but allows an adequate adjustment of the frictional force to perform fine hand movements. Palmar hyperhidrosis is a chronic neurologic disorder characterized by excessive sweating of eccrine glands due to overactivity of the sympathetic nervous system. Palmar sweating and emotional processing are controlled by the limbic system. In this case report reduction of palmar sweating was associated with a sense of well-being. Corticotropin releasing factor (CRF) and adrenocorticotropic hormone (ACTH) are the two main hypothalamic hormones that interact with both the limbic system and the peripheral sympathetic nervous system. Tolvaptan is an arginine vasopressin (AVP) antagonist. AVP has effects on the sympathetic nervous system through both central and peripheral actions. Centrally AVP is a well-known ACTH secretagogue. Remission of palmar hyperhidrosis is probably mediated by tolvaptan acting on central ACTH secretion.
    Keywords:  ADPKD; Arginine vasopressin; Palmar hyperhidrosis; Tolvaptan; Vasopressin antagonists
    DOI:  https://doi.org/10.1007/s40620-021-00973-8
  14. Autophagy. 2021 Feb 08.
    Autophagy-dependent regulation of skeletal muscle regeneration and strength by a RHOGEF.
    Jae-Sung You, Jie Chen.
      Macroautophagy/autophagy plays a critical role in restoring/maintaining skeletal muscle function under normal conditions as well as during damage-induced regeneration. This homeostatic degradation mechanism, however, rapidly declines with aging leading to functional deterioration of skeletal muscles. ARHGEF3 is a RHOA- and RHOB-specific GEF capable of inhibiting myogenic AKT signaling independently of its GEF function. Our recent study reveals that ARHGEF3 negatively regulates skeletal muscle autophagy during injury-induced regeneration and normal aging. By enhancing autophagy, arhgef3 knockout augments the regenerative capacity of muscles in both young and regeneration-defective middle-aged mice and prevents age-related loss of muscle strength. We further show that the GEF activity of ARHGEF3 toward ROCK, but not its downstream target AKT, mediates its function in muscle regeneration. These findings suggest that ARHGEF3 may be a candidate therapeutic target for impaired muscle regeneration, age-related muscle weakness, and potentially other diseases arising from aberrant regulation of autophagy.
    Keywords:  AKT; ARHGEF3; Aging; RHOA; ROCK; autophagy; injury; regeneration; skeletal muscle; strength
    DOI:  https://doi.org/10.1080/15548627.2021.1886721
  15. Ann Transl Med. 2021 Jan;9(2): 120
    Association of a novel PKHD1 mutation in a family with autosomal dominant polycystic liver disease.
    Jiaru Wang, Huayu Yang, Ruohan Guo, Xinting Sang, Yilei Mao.
       Background: Autosomal dominant polycystic liver disease (ADPLD) is characterized by multiple cysts in the liver without (or only occasional) renal cysts. At least seven genes are associated with high risk for developing ADPLD; however, clear genetic involvement is undetermined in more than 50% of ADPLD patients.
    Methods: To identify additional ADPLD-associated genes, we collected 18 unrelated Chinese ADPLD cases, and performed whole exome sequencing on all the participants. After filtering the sequencing data against the human gene mutation database (HGMD) professional edition, we identified new mutations. We then sequenced this gene in family members of the patient.
    Results: Among the 18 ADPLD cases analyzed by whole exome sequencing, we found 2 cases with a PRKCSH mutation (~11.1%), 2 cases with a PKD2 mutation (~11.1%), 1 case with both PKHD1 and PKD1 mutations (~5.6%), 1 case with GANAB mutation (~5.6%), 1 case with PKHD1 mutation (~5.6%), and 1 case with PKD1 mutations (~5.6%). We identified a new PKHD1 missense mutation in an ADPLD family, in which both patients showed innumerable small hepatic cysts, as reported previously. Additionally, we found that PRKCSH and SEC63 mutation frequencies were lower in the Chinese population compared with those in European and American populations.
    Conclusions: We report a family with ADPLD associated with a novel PKHD1 mutation (G1210R). The genetic profile of ADPLD in the Chinese population is different from that in European and American populations, suggesting that further genetic research on genetic mutation of ADPLD in the Chinese population is warranted.
    Keywords:  Autosomal dominant polycystic liver disease (ADPLD); PKHD1; genetic profile; new gene mutation
    DOI:  https://doi.org/10.21037/atm-20-3318
  16. Am J Physiol Gastrointest Liver Physiol. 2021 Feb 10.
    Targeted Intestinal Deletion of Rho Guanine Nucleotide Exchange Factor 7, βPIX, Impairs Enterocyte Proliferation, Villus Maturation and Mucosal Defenses in Mice.
    Kunrong Cheng, Shannon M Larabee, Mazen Tolaymat, Marie Hanscom, Aaron C Shang, Alyssa Schledwitz, Shien Hu, Cinthia B Drachenberg, Min Zhan, Ahmed Chahdi, Jean-Pierre Raufman.
      Rho guanine nucleotide exchange factors (RhoGEFs) regulate Rho GTPase activity and cytoskeletal and cell adhesion dynamics. βPix, a CDC42/RAC family RhoGEF encoded by ARHGEF7, is reported to modulate human colon cancer cell proliferation and post-wounding restitution of rat intestinal epithelial monolayers. We hypothesized βPix plays a role in maintaining intestinal epithelial homeostasis. To test this hypothesis, we examined βPix distribution in the human and murine intestine and created mice with intestinal epithelial-selective βPix deletion [βPixflox/flox/Tg(Villin-Cre); Arhgef7 CKO mice]. Using Arhgef7 CKO and control mice, we investigated the consequences of βPix deficiency in vivo on intestinal epithelial and enteroid development, dextran sodium sulfate-induced mucosal injury, and gut permeability. In normal human and murine intestines, we observed diffuse cytoplasmic and moderate nuclear βPix immunostaining in enterocytes. Arhgef7 CKO mice were viable and fertile with normal gross intestinal architecture but reduced small intestinal villus height, villus/crypt ratio, and goblet cells; small intestinal crypt cells had reduced Ki67 staining, compatible with impaired cell proliferation. Enteroids derived from control mouse small intestine were viable for more than 20 passages, but those from Arhgef7 CKO mice did not survive beyond 24 h despite adding Wnt proteins or conditioned media from normal enteroids. Adding a Rho kinase (ROCK) inhibitor partially rescued CKO enteroid development. Compared to littermate control mice, dextran sodium sulfate-treated βPix-deficient mice lost more weight, had greater impairment of intestinal barrier function, and more severe colonic mucosal injury. These findings reveal βPix expression is important for enterocyte development, intestinal homeostasis and resistance to toxic injury.
    Keywords:  Rho-associated protein kinase; beta-catenin signaling; cell proliferation; intestinal epithelial cells; intestinal organoids
    DOI:  https://doi.org/10.1152/ajpgi.00415.2020
  17. Eur Rev Med Pharmacol Sci. 2021 Jan;pii: 24667. [Epub ahead of print]25(2): 976-984
    Propofol relieves inflammation in MIRI rats by inhibiting Rho/Rock signaling pathway.
    C Liu, Y Li.
       OBJECTIVE: The aim of this study was to investigate the effects of propofol on myocardial ischemia-reperfusion injury (MIRI) and its mechanism by establishing in vivo rat models.
    MATERIALS AND METHODS: Sprague-Dawley rats were selected for the construction of MIRI models in vivo. All rats were divided into three groups, including sham operation group (Sham operation), MIRI group and MIRI + propofol group. At 2 h after reperfusion, myocardial tissues and blood samples were collected from rats. The expression levels of serum lactic dehydrogenase (LDH) and creatine kinase-MB (CK-MB), as well as serum interleukin-6 (IL-6), IL-10 and tumor necrosis factor-α (TNF-α), were measured in each group of rats, respectively. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay was employed to detect the apoptosis of myocardial cells. Additionally, the messenger ribonucleic acid (mRNA) and protein expressions of Ras homolog gene family, member A (RhoA) and Rho-associated coiled-coil-containing protein kinase 2 (Rock2) were determined via quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting, respectively.
    RESULTS: (1) The expression levels of serum LDH and CK-MB were significantly lower in MIRI + propofol group than those in MIRI group (p<0.05). (2) In comparison with MIRI group, MIRI + propofol group exhibited significantly reduced serum IL-6 and TNF-α levels (p<0.01) and elevated serum IL-10 level (p<0.01). (3) Compared with MIRI group, the apoptosis of myocardial cells was remarkably reduced in MIRI + propofol group after IRI (p<0.05). (4) The mRNA and protein expressions of RhoA and Rock2 were significantly lower in MIRI + propofol group than those in MIRI group (p<0.05).
    CONCLUSIONS: Propofol relieves MIRI and inflammation, reduces the level of oxidative stress and represses I/R-induced myocardial cell apoptosis in MIRI rats by inhibiting the activity of the Rho/Rock signaling pathway.
    DOI:  https://doi.org/10.26355/eurrev_202101_24667
  18. Ann Transl Med. 2021 Jan;9(2): 165
    Actin-granule formation is an additional step in cardiac myofibroblast differentiation.
    Li He, Ruiqi Liu, Honghua Yue, Shuofang Ren, Guonian Zhu, Yingqiang Guo, Chaoyi Qin.
       Background: Atrial fibrillation is the most common and long-lasting cardiac arrhythmia, and profoundly effects the daily lives of patients. The pathogenesis and persistence of atrial fibrillation is closely related to the cardiac fibroblast and its myofibroblast differentiation as increased collagen synthesis and migration capability. Thus better understanding of myofibroblast differentiation is essential for the prevention and treatment of atrial fibrillation.
    Methods: Cardiac fibroblasts were isolated from neonatal rats and its actin structure was analyzed by immunofluorescence staining. Myofibroblast differentiation was induced by Angiotensin II (Ang II) and ROCK signaling related proteins were determined by western blot. Fasudil and Ricolinostat were employed to abrogate ROCK signaling and their effects on myofibroblast differentiation were assessed by IF microscopy and Celigo Image Cytometry.
    Results: Stress actin fibers similar to actin filaments in myofibroblast differentiation are regulated by ROCK signaling, and our results also suggested Guanine nucleotide exchange factor-H1 (GEF-H1) phosphorylation could be induced by Ang II. In addition, Fasudil could down-regulate RhoA, GEF-H1, and phosphorylated GEF-H1 to inhibit ROCK signaling and further reduce Col I expression and the myofibroblast proportion.
    Conclusions: An individual phase characterized by actin-granule formation was identified in cardiac myofibroblast differentiation. In the meanwhile, myofibroblast differentiation and its F-actin assembly could be detained in this phase by Fasudil abrogating the ROCK signaling pathway.
    Keywords:  Fibrosis; ROCK; actin-granule; myofibroblast differentiation; stress actin fiber
    DOI:  https://doi.org/10.21037/atm-20-8231
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