bims-bicyki Biomed News
on Bicaudal-C1 and interactors in cystic kidney disease
Issue of 2021‒09‒05
twelve papers selected by
Céline Gagnieux
École Polytechnique Fédérale de Lausanne (EPFL)
  1. The chloride channel CFTR is not required for cyst growth in an ADPKD mouse model.
  2. The effect of trichlormethiazide in autosomal dominant polycystic kidney disease patients receiving tolvaptan: a randomized crossover controlled trial.
  3. Inhibiting Focal Adhesion Kinase Ameliorates Cyst Development in Polycystin-1-Deficient Polycystic Kidney Disease in Animal Model.
  4. Greater adherence to the dietary approaches to stop hypertension dietary pattern is associated with preserved muscle strength in patients with autosomal dominant polycystic kidney disease: a single-center cross-sectional study.
  5. Establishment of a Ciliogenesis-Associated Signaling Model for Polycystic Kidney Disease.
  6. Differential Roles of Tubby Family Proteins in Ciliary Formation and Trafficking.
  7. Effect of Naoluoxintong on the NogoA/RhoA/ROCK pathway by down-regulating DNA methylation in MCAO rats.
  8. NudCL2 is an autophagy receptor that mediates selective autophagic degradation of CP110 at mother centrioles to promote ciliogenesis.
  9. LPA1-mediated PKD2 activation promotes LPA-induced tissue factor expression via the p38α and JNK2 MAPK pathways in smooth muscle cells.
  10. Serum phosphorus and calcium levels, and kidney disease progression in immunoglobulin A nephropathy.
  11. YAP facilitates melanoma migration through regulation of actin-related protein 2/3 complex subunit 5 (ARPC5).
  12. Crosstalk between myosin II and formin functions in the regulation of force generation and actomyosin dynamics in stress fibers.
  1. FASEB J. 2021 Oct;35(10): e21897
    The chloride channel CFTR is not required for cyst growth in an ADPKD mouse model.
    Khaoula Talbi, Inês Cabrita, Andre Kraus, Sascha Hofmann, Kathrin Skoczynski, Karl Kunzelmann, Bjoern Buchholz, Rainer Schreiber.
      Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the development of bilateral renal cysts which enlarge continuously, leading to compression of adjacent intact nephrons. The growing cysts lead to a progressive decline in renal function. Cyst growth is driven by enhanced cell proliferation and chloride secretion into the cyst lumen. Chloride secretion is believed to occur mainly by the cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR), with some contribution by the calcium-activated chloride channel TMEM16A. However, our previous work suggested TMEM16A as a major factor for renal cyst formation. The contribution of CFTR to cyst formation has never been demonstrated in an adult ADPKD mouse model. We used mice with an inducible tubule-specific Pkd1 knockout, which consistently develop polycystic kidneys upon deletion of Pkd1. Cellular properties, ion currents, and cyst development in these mice were compared with that of mice carrying a co-deletion of Pkd1 and Cftr. Knockout of Cftr did not reveal any significant impact on cyst formation in the ADPKD mouse model. Furthermore, knockout of Cftr did not attenuate the largely augmented cell proliferation observed in Pkd1 knockout kidneys. Patch clamp analysis on primary renal epithelial cells lacking expression of Pkd1 indicated an only marginal contribution of CFTR to whole cell Cl- currents, which were clearly dominated by calcium-activated TMEM16A currents. In conclusion, CFTR does not essentially contribute to renal cyst formation in mice caused by deletion of Pkd1. Enhanced cell proliferation and chloride secretion is caused primarily by upregulation of the calcium-activated chloride channel TMEM16A.
    Keywords:  ADPKD; CFTR; TMEM16A; cyst growth; proliferation
    DOI:  https://doi.org/10.1096/fj.202100843R
  2. Sci Rep. 2021 Sep 03. 11(1): 17666
    The effect of trichlormethiazide in autosomal dominant polycystic kidney disease patients receiving tolvaptan: a randomized crossover controlled trial.
    Kiyotaka Uchiyama, Chigusa Kitayama, Akane Yanai, Yoshitaka Ishibashi.
      The vasopressin V2 receptor antagonist tolvaptan delays the progression of autosomal dominant polycystic kidney disease (ADPKD). However, some patients discontinue tolvaptan because of severe adverse aquaretic events. This open-label, randomized, controlled, counterbalanced, crossover trial investigated the effects of trichlormethiazide, a thiazide diuretic, in patients with ADPKD receiving tolvaptan (n = 10) who randomly received antihypertensive therapy with or without trichlormethiazide for 12 weeks. The primary and secondary outcomes included amount and osmolarity of 24-h urine and health-related quality-of-life (HRQOL) parameters assessed by the Kidney Disease Quality of Life-Short Form questionnaire, renal function slope, and plasma/urinary biomarkers associated with disease progression. There was a significant reduction in urine volume (3348 ± 584 vs. 4255 ± 739 mL; P < 0.001) and a significant increase in urinary osmolarity (182.5 ± 38.1 vs. 141.5 ± 38.1 mOsm; P = 0.001) in patients treated with trichlormethiazide. Moreover, trichlormethiazide improved the following HRQOL subscales: effects of kidney disease, sleep, emotional role functioning, social functioning, and role/social component summary. No significant differences were noted in renal function slope or plasma/urinary biomarkers between patients treated with and without trichlormethiazide. In patients with ADPKD treated with tolvaptan, trichlormethiazide may improve tolvaptan tolerability and HRQOL parameters.
    DOI:  https://doi.org/10.1038/s41598-021-97113-w
  3. J Am Soc Nephrol. 2021 Sep;32(9): 2159-2174
    Inhibiting Focal Adhesion Kinase Ameliorates Cyst Development in Polycystin-1-Deficient Polycystic Kidney Disease in Animal Model.
    Jinzhao He, Shun Zhang, Zhiwei Qiu, Xiaowei Li, Huihui Huang, William Jin, Yue Xu, Guangying Shao, Liang Wang, Jia Meng, Shuyuan Wang, Xiaoqiang Geng, Yingli Jia, Min Li, Baoxue Yang, Hua A Jenny Lu, Hong Zhou.
      BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is characterized by numerous cysts originating from renal tubules and is associated with significant tubular epithelial cell proliferation. Focal adhesion kinase (FAK) promotes tumor growth by regulating multiple proliferative pathways.METHODS: We established the forskolin (FSK)-induced three-dimensional (3D) Madin-Darby Canine Kidney cystogenesis model and 8-bromoadenosine-3`,5`-cyclic monophosphate-stimulated cyst formation in ex vivo embryonic kidney culture. Cultured human renal cyst-lining cells (OX-161) and normal tubular epithelial cells were treated with FAK inhibitors or transfected with green fluorescent protein-tagged FAK mutant plasmids for proliferation study. Furthermore, we examined the role of FAK in two transgenic ADPKD animal models, the kidney-specific Pkd1 knockout and the collecting duct-specific Pkd1 knockout mouse models.
    RESULTS: FAK activity was significantly elevated in OX-161 cells and in two ADPKD mouse models. Inhibiting FAK activity reduced cell proliferation in OX-161 cells and prevented cyst growth in ex vivo and 3D cyst models. In tissue-specific Pkd1 knockout mouse models, FAK inhibitors retarded cyst development and mitigated renal function decline. Mechanically, FSK stimulated FAK activation in tubular epithelial cells, which was blocked by a protein kinase A (PKA) inhibitor. Inhibition of FAK activation by inhibitors or transfected cells with mutant FAK constructs interrupted FSK-mediated Src activation and upregulation of ERK and mTOR pathways.
    CONCLUSIONS: Our study demonstrates the critical involvement of FAK in renal cyst development, suggests that FAK is a potential therapeutic target in treating patients with ADPKD, and highlights the role of FAK in cAMP-PKA-regulated proliferation.
    Keywords:  ADPKD; FAK; cAMP; cyst growth; proliferation
    DOI:  https://doi.org/10.1681/ASN.2020111560
  4. Nutr Res. 2021 Jul 25. pii: S0271-5317(21)00048-8. [Epub ahead of print]93 99-110
    Greater adherence to the dietary approaches to stop hypertension dietary pattern is associated with preserved muscle strength in patients with autosomal dominant polycystic kidney disease: a single-center cross-sectional study.
    Hyunjin Ryu, Yun Jung Yang, Eunjeong Kang, Curie Ahn, Soo Jin Yang, Kook-Hwan Oh.
      The present study aimed to determine whether certain diets lower the risk of low muscle strength in patients with autosomal dominant polycystic kidney disease (ADPKD). In this cross-sectional study, outpatient ADPKD patients were enrolled from a tertiary care hospital. Muscle strength was assessed on the basis of handgrip strength (HGS), and dietary pattern indices were calculated using dietary intake data. Among the 68 participants included in this study, 19 (27.9%) had low HGS. Cystatin C concentrations were significantly higher in all participants, and in women in the low compared to the normal HGS group in the unadjusted analyses (P = 0.004). Among analyzed dietary pattern indices, the Dietary Approaches to Stop Hypertension (DASH) score was lower, for all participants and men, in the low compared to the normal HGS group (P < 0.05). Especially, the component score for whole grains of the DASH score was significantly lower in men in the low compared to the normal HGS group in unadjusted analyses. The DASH score was positively correlated with HGS in men (r = 0.387, P = 0.046). In addition, logistic regression analysis showed that the DASH score was negatively associated with low HGS, for all participants (odds ratio = 0.851, P = 0.049) and men (odds ratio = 0.716, P = 0.043), after adjusting for age, sex, and body weight. These findings suggest that the DASH dietary pattern may promote the preservation of muscle strength in ADPKD patients. The DASH diet can be considered as a nutritional strategy to maintain muscle strength and prevent sarcopenia in ADPKD patients.
    Keywords:  Dietary pattern; Handgrip strength; Muscle strength; Polycystic kidney disease; Sarcopenia
    DOI:  https://doi.org/10.1016/j.nutres.2021.07.006
  5. Kidney Blood Press Res. 2021 Sep 01. 1-9
    Establishment of a Ciliogenesis-Associated Signaling Model for Polycystic Kidney Disease.
    Ling Lu, Qiuling Liu, Lei Zhi, Xuchun Che, Bo Xiao, Mingxuan Cui, Mingyu Yu, Bing Yang, Jingjing Zhang, Bo Zhang.
      BACKGROUND: Polycystic kidney disease (PKD) represents the most prevalent inherited progressive kidney disorder in humans. Due to complexity of the genetic network behind the disease, the molecular mechanisms of PKD are still poorly understood yet.OBJECTIVES: This study aimed to develop a ciliogenesis-associated gene network for PKD patients and comprehensively understand the molecular mechanisms underlying the disease.
    METHOD: The potential hub genes were selected based on the differential expression analysis from the GEO database. Meanwhile, the primary hub genes were further elucidated by both in vivo and in vitro experiments.
    RESULTS: In this study, we established a comprehensive differentially expressed genes profile (including GNAS, PI4KB, UMOD, SLC7A13, and MIOX) for PKD patients compared with the control specimen. At the same time, enrichment analysis was utilized to demonstrate that the G-protein-related signaling and cilia assembling signaling pathways were closely associated with PKD development. The further investigations of the interaction between 2 genes (GNAS and PI4KB) with in vivo and in vitro analyses revealed that PI4KB functioned as a downstream factor for GNAS and spontaneously activated the phosphorylation of Akt into p-Akt for ciliogenesis in PKD formation. The PI4KB depletion mutant zebrafish model displayed a PKD phenotype as well as absence of primary cilia in the kidney.
    CONCLUSIONS: Collectively, our work discovered an innovative potential signaling pathway model for PKD formation, which provided a valuable insight for future study of the mechanism of this disease.
    Keywords:  GNAS; Phosphatidylinositol 4 kinase III-β; Polycystic kidney disease; Primary cilia
    DOI:  https://doi.org/10.1159/000517408
  6. Mol Cells. 2021 Aug 31. 44(8): 591-601
    Differential Roles of Tubby Family Proteins in Ciliary Formation and Trafficking.
    Julie J Hong, Kyung Eun Kim, So Young Park, Jinwoong Bok, Jeong Taeg Seo, Seok Jun Moon.
      Cilia are highly specialized organelles that extend from the cell membrane and function as cellular signaling hubs. Thus, cilia formation and the trafficking of signaling molecules into cilia are essential cellular processes. TULP3 and Tubby (TUB) are members of the tubby-like protein (TULP) family that regulate the ciliary trafficking of G-protein coupled receptors, but the functions of the remaining TULPs (i.e., TULP1 and TULP2) remain unclear. Herein, we explore whether these four structurally similar TULPs share a molecular function in ciliary protein trafficking. We found that TULP3 and TUB, but not TULP1 or TULP2, can rescue the defective cilia formation observed in TULP3-knockout (KO) hTERT RPE-1 cells. TULP3 and TUB also fully rescue the defective ciliary localization of ARL13B, INPP5E, and GPR161 in TULP3 KO RPE-1 cells, while TULP1 and TULP2 only mediate partial rescues. Furthermore, loss of TULP3 results in abnormal IFT140 localization, which can be fully rescued by TUB and partially rescued by TULP1 and TULP2. TUB's capacity for binding IFT-A is essential for its role in cilia formation and ciliary protein trafficking in RPE-1 cells, whereas its capacity for PIP2 binding is required for proper cilia length and IFT140 localization. Finally, chimeric TULP1 containing the IFT-A binding domain of TULP3 fully rescues ciliary protein trafficking, but not cilia formation. Together, these two TULP domains play distinct roles in ciliary protein trafficking but are insufficient for cilia formation in RPE-1 cells. In addition, TULP1 and TULP2 play other unknown molecular roles that should be addressed in the future.
    Keywords:  RPE1; TULP; cilia; cilia formation; ciliary trafficking
    DOI:  https://doi.org/10.14348/molcells.2021.0082
  7. J Ethnopharmacol. 2021 Aug 27. pii: S0378-8741(21)00788-1. [Epub ahead of print] 114559
    Effect of Naoluoxintong on the NogoA/RhoA/ROCK pathway by down-regulating DNA methylation in MCAO rats.
    Lu Hong, Weidong Chen, Ling He, Hui Tan, Daiyin Peng, Guodong Zhao, Xiaoqian Shi, Lei Wang, Mingming Liu, Huihui Jiang.
      ETHNOPHARMACOLOGICAL RELEVANCE: Naoluoxintong (NLXT) is a traditional Chinese Medicine (TCM) prescription that is clinically used in the treatment of ischemic stroke (IS). However, its therapeutic mechanism remains unclear.AIM OF THE STUDY: To obtain the mechanism of NLXT by observing the protective effects of NLXT on the NogoA/RhoA/Rock pathway in a rat model of IS by regulating DNA methylation.
    MATERIALS AND METHODS: Rats were divided into five groups using a random number table: normal group, model group, NLXT group, blocker group I (NLXT + SGI-1027) and blocker group II (NLXT + Y27632). The right middle cerebral artery occlusion-reperfusion (MCAO/R) rat model was made, and the regional cerebral blood flow (rCBF) of each group was detected using laser Doppler. The methylation levels of CpG sites of neurite outgrowth inhibitor protein-A (Nogo-A), Nogo receptor (NgR), ras homolog gene family member A (RhoA) and rho-associated coiled-coil protein kinase 2 (ROCK2) genes in rat brain tissue were detected using the bisulfite method. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect NogoA, RhoA, NgR1, NgR2 and ROCK2 mRNA expression in rat brain tissue. NogoA, RhoA, NgR1, NgR2 and ROCK2 proteins were detected using immunoblotting in rat brain tissue.
    RESULTS: After the modeling of middle cerebral artery occlusion (MCAO), neurological deficit test was made to ensure the success of the modeling. At each time point after surgery, the rCBF of the other groups decreased compared with the normal group (P < 0.01 or P < 0.05). Meanwhile, the rCBF increased in blocker group I as well as blocker group II after 3 days (P < 0.05). There were differences in the DNA methylation sites of NogoA, RhoA, NgR and ROCK2 genes between the model group and the NLXT group (P < 0.05). Compared with the normal group, NogoA, NgR1, NgR2, RhoA and ROCK2 gene expression in the model group increased observably (P < 0.01). In comparison with the model group, NogoA and NgR1 gene expression in the blocker group II was prominently observed on the 1st day. NogoA, NgR1, NgR2, RhoA and ROCK2 gene expression remarkably reduced (P < 0.01) on the 3rd and 7th days. Compared with the normal group, NogoA, RhoA, NgR1, NgR2 and ROCK2 protein expression in the model group increased observably (P < 0.01). In comparison with the model group, NogoA, RhoA, NgR1, NgR2 and ROCK2 protein expression in the other groups declined prominently (P < 0.01).
    CONCLUSION: NLXT can reduce the DNA methylation level of NogoA pathway after IS, thus inhibit the expression of NogoA/RhoA/ROCK pathway from producing anti-cerebral ischemia pharmacological effect.
    Keywords:  DNA methylation; Ischemic stroke; Naoluoxintong (NLXT); NogoA/RhoA/ROCK pathway
    DOI:  https://doi.org/10.1016/j.jep.2021.114559
  8. Cell Res. 2021 Sep 03.
    NudCL2 is an autophagy receptor that mediates selective autophagic degradation of CP110 at mother centrioles to promote ciliogenesis.
    Min Liu, Wen Zhang, Min Li, Jiaxing Feng, Wenjun Kuang, Xiying Chen, Feng Yang, Qiang Sun, Zhangqi Xu, Jianfeng Hua, Chunxia Yang, Wei Liu, Qiang Shu, Yuehong Yang, Tianhua Zhou, Shanshan Xie.
      Primary cilia extending from mother centrioles are essential for vertebrate development and homeostasis maintenance. Centriolar coiled-coil protein 110 (CP110) has been reported to suppress ciliogenesis initiation by capping the distal ends of mother centrioles. However, the mechanism underlying the specific degradation of mother centriole-capping CP110 to promote cilia initiation remains unknown. Here, we find that autophagy is crucial for CP110 degradation at mother centrioles after serum starvation in MEF cells. We further identify NudC-like protein 2 (NudCL2) as a novel selective autophagy receptor at mother centrioles, which contains an LC3-interacting region (LIR) motif mediating the association of CP110 and the autophagosome marker LC3. Knockout of NudCL2 induces defects in the removal of CP110 from mother centrioles and ciliogenesis, which are rescued by wild-type NudCL2 but not its LIR motif mutant. Knockdown of CP110 significantly attenuates ciliogenesis defects in NudCL2-deficient cells. In addition, NudCL2 morphants exhibit ciliation-related phenotypes in zebrafish, which are reversed by wild-type NudCL2, but not its LIR motif mutant. Importantly, CP110 depletion significantly reverses these ciliary phenotypes in NudCL2 morphants. Taken together, our data suggest that NudCL2 functions as an autophagy receptor mediating the selective degradation of mother centriole-capping CP110 to promote ciliogenesis, which is indispensable for embryo development in vertebrates.
    DOI:  https://doi.org/10.1038/s41422-021-00560-3
  9. J Biol Chem. 2021 Aug 31. pii: S0021-9258(21)00954-6. [Epub ahead of print] 101152
    LPA1-mediated PKD2 activation promotes LPA-induced tissue factor expression via the p38α and JNK2 MAPK pathways in smooth muscle cells.
    Feng Hao, Qiwei Liu, Fuqiang Zhang, Jiaxin Du, Amanda Dumire, Xuemin Xu, Mei-Zhen Cui.
      Tissue factor (TF) is the principal initiator of blood coagulation and is necessary for thrombosis. We previously reported that lysophosphatidic acid (LPA), a potent bioactive lipid, highly induces TF expression at the transcriptional level in vascular smooth muscle cells. To date, however, the specific role of the LPA receptor is unknown, and the intracellular signaling pathways that lead to LPA induction of TF have been largely undetermined. In the current study, we found that LPA markedly induced protein kinase D (PKD) activation in mouse aortic smooth muscle cells (MASMCs). Small-interfering RNA-mediated knockdown of PKD2 blocked LPA-induced TF expression and activity, indicating that PKD2 is the key intracellular mediator of LPA signaling leading to the expression and cell surface activity of TF. Furthermore, our data reveal a novel finding that PKD2 mediates LPA-induced TF expression via the p38α and JNK2 MAPK signaling pathways, which are accompanied by the PKD-independent MEK1/2-ERK-JNK pathway. To identify the LPA receptor(s) responsible for LPA-induced TF expression, we isolated MASMCs from LPA receptor-knockout mice. Our results demonstrated that SMCs isolated from LPA receptor 1 (LPA1)-deficient mice completely lost responsiveness to LPA stimulation, which mediates induction of TF expression and activation of PKD and p38/JNK MAPK, indicating that LPA1 is responsible for PKD2-mediated activation of JNK2 and p38α. Taken together, our data reveal a new signaling mechanism in which the LPA1-PKD2 axis mediates LPA-induced TF expression via the p38α and JNK2 pathways. This finding provides new insights into LPA signaling, the PKD2 pathway, and the mechanisms of coagulation/atherothrombosis.
    Keywords:  atherosclerosis; gene expression; lipid signaling; signal transduction; smooth muscle cells; vascular biology
    DOI:  https://doi.org/10.1016/j.jbc.2021.101152
  10. Clin Kidney J. 2021 Sep;14(9): 2108-2113
    Serum phosphorus and calcium levels, and kidney disease progression in immunoglobulin A nephropathy.
    Guizhen Yu, Jun Cheng, Yan Jiang, Heng Li, Xiayu Li, Jianghua Chen.
      Background: Disorders of calcium and phosphorus metabolism have been reported to be associated with all-cause and cardiovascular mortality in patients requiring long-term dialysis therapy. However, its role in disease progression is not well established in patients without dialysis, especially in immunoglobulin A (IgA) nephropathy. We aim to evaluate the association of serum phosphorus and calcium and progression of IgA nephropathy.Methods: We assessed 2567 patients with IgA nephropathy at the First Affiliated Hospital, College of Medicine, Zhejiang University. Serum phosphorus and calcium were collected at the time of kidney biopsy and at each visit. The associations of serum phosphorus and serum calcium with composite kidney disease progression events, defined as 50% estimated glomerular filtration rate (eGFR) decline and kidney failure, were examined using Cox models and restricted cubic splines.
    Results: During a median follow-up of 31.9 months, 248 (10%) patients reached composite kidney disease progression events. A linear relationship was observed between serum phosphorus and composite kidney disease progression events. With higher levels of phosphorus, the risk of kidney disease progression events increased {hazard ratio [HR] 3.54 [95% confidence interval (CI) 1.37-9.12]; P = 0.009}. Compared with the first quartile group, the HR of kidney disease progression events was 1.66 (95% CI 0.91-301) for the second quartile, 1.67 (95% CI 0.91-3.08) for the third and 2.62 (95% CI 1.44-4.77) for the fourth (P for trend = 0.002). The association between serum phosphorus and kidney disease progression was detectable [HR 8.94 (95% CI 2.33-34.21); P = 0.001] within the subgroup with eGFR <60 mL/min/1.73 m2 but not among patients with eGFR ≥60 mL/min/1.73 m2 [HR 0.87 (95% CI 0.17-4.44); P = 0.87]. After adjustment for traditional risk factors, a higher level of serum calcium was not associated with kidney disease progression events [HR 0.33 (95% CI 0.10-1.09)].
    Conclusions: Higher serum phosphorus rather than serum calcium was independently associated with kidney disease progression in IgA nephropathy.
    Keywords:  IgA nephropathy; kidney disease progression; serum calcium; serum phosphorus
    DOI:  https://doi.org/10.1093/ckj/sfab002
  11. Pigment Cell Melanoma Res. 2021 Sep 01.
    YAP facilitates melanoma migration through regulation of actin-related protein 2/3 complex subunit 5 (ARPC5).
    Jason W Lui, Stephen P G Moore, Lee Huang, Kelsey Ogomori, Yan Li, Deborah Lang.
      Yes-associated protein 1 (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are transcriptional coactivators that have been implicated in driving metastasis and progression in many cancers, mainly through their transcriptional regulation of downstream targets. Although YAP and TAZ have shown redundancy in many contexts, it is still unknown whether or not this is true in melanoma. Here, we show that while both YAP and TAZ are expressed in a panel of melanoma cell lines, depletion of YAP results in decreased cell numbers, focal adhesions, and the ability to invade matrigel. Using non-biased RNA-sequencing analysis, we find that melanoma cells depleted of YAP, TAZ, or YAP/TAZ exhibit drastically different transcriptomes. We further uncover the ARP2/3 subunit ARPC5 as a specific target of YAP but not TAZ and that ARPC5 is essential for YAP-dependent maintenance of melanoma cell focal adhesion numbers. Our findings suggest that in melanoma, YAP drives melanoma progression, survival, and invasion.
    Keywords:  ARP2/3 complex; cancer; melanoma; transcriptional coactivator; yes-associated protein (YAP)
    DOI:  https://doi.org/10.1111/pcmr.13013
  12. Cells Dev. 2021 Aug 26. pii: S2667-2901(21)00070-X. [Epub ahead of print] 203736
    Crosstalk between myosin II and formin functions in the regulation of force generation and actomyosin dynamics in stress fibers.
    Yukako Nishimura, Shidong Shi, Qingsen Li, Alexander D Bershadsky, Virgile Viasnoff.
      REF52 fibroblasts have a well-developed contractile machinery, the most prominent elements of which are actomyosin stress fibers with highly ordered organization of actin and myosin IIA filaments. The relationship between contractile activity and turnover dynamics of stress fibers is not sufficiently understood. Here, we simultaneously measured the forces exerted by stress fibers (using traction force microscopy or micropillar array sensors) and the dynamics of actin and myosin (using photoconversion-based monitoring of actin incorporation and high-resolution fluorescence microscopy of myosin II light chain). Our data revealed new features of the crosstalk between myosin II-driven contractility and stress fiber dynamics. During normal stress fiber turnover, actin incorporated all along the stress fibers and not only at focal adhesions. Incorporation of actin into stress fibers/focal adhesions, as well as actin and myosin II filaments flow along stress fibers, strongly depends on myosin II activity. Myosin II-dependent generation of traction forces does not depend on incorporation of actin into stress fibers per se, but still requires formin activity. This previously overlooked function of formins in maintenance of the actin cytoskeleton connectivity could be the main mechanism of formin involvement in traction force generation.
    Keywords:  Actomyosin flow; Cell traction forces; Para-aminoblebbistatin; SMIFH2; Structured illumination microscopy (SIM); Ventral stress fibers
    DOI:  https://doi.org/10.1016/j.cdev.2021.203736
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