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1.
J Cell Biol ; 222(2)2023 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-36574264

RESUMO

Contractile epithelial tubes are found in various organs, such as lung airways and blood capillaries. Their ability to sense luminal pressure and respond with adequate contractility is essential for their physiology, and its mis-regulation results in diseases such as asthma and hypertension. Here, we describe a mechanoresponsive regulatory pathway downstream of tissue stretching that controls contraction of the C. elegans spermatheca, a tubular structure where fertilization occurs. Using live-imaging, we show that ovulation-induced stretching of spermathecal cells leads to recruitment of the RhoGEF RHGF-1 to stress fibers, which activates RHO-1 and myosin II in a positive feedback loop. Through deletion analysis, we identified the PDZ domain of RHGF-1 as responsible for F-actin binding, and genetic epistasis analysis with the RhoGAP spv-1 demonstrated that tension-dependent recruitment of RHGF-1 to F-actin is required for robust spermathecal contractility. Our study illustrates how mechanosensitive regulators of Rho GTPases provide epithelial tubes the ability to tune their contractility in response to internal pressure.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Animais , Feminino , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Actinas/metabolismo , Fibras de Estresse/metabolismo , Contração Muscular , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Proteínas rho de Ligação ao GTP/genética , Proteínas rho de Ligação ao GTP/metabolismo , Proteínas Ativadoras de GTPase/metabolismo
2.
Mol Biol Cell ; 30(7): 907-922, 2019 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-30726159

RESUMO

Contractility of the nonmuscle and smooth muscle cells that comprise biological tubing is regulated by the Rho-ROCK (Rho-associated protein kinase) and calcium signaling pathways. Although many molecular details about these signaling pathways are known, less is known about how they are coordinated spatiotemporally in biological tubes. The spermatheca of the Caenorhabditis elegans reproductive system enables study of the signaling pathways regulating actomyosin contractility in live adult animals. The RhoGAP (GTPase--activating protein toward Rho family small GTPases) SPV-1 was previously identified as a negative regulator of RHO-1/Rho and spermathecal contractility. Here, we uncover a role for SPV-1 as a key regulator of calcium signaling. spv-1 mutants expressing the calcium indicator GCaMP in the spermatheca exhibit premature calcium release, elevated calcium levels, and disrupted spatial regulation of calcium signaling during spermathecal contraction. Although RHO-1 is required for spermathecal contractility, RHO-1 does not play a significant role in regulating calcium. In contrast, activation of CDC-42 recapitulates many aspects of spv-1 mutant calcium signaling. Depletion of cdc-42 by RNA interference does not suppress the premature or elevated calcium signal seen in spv-1 mutants, suggesting other targets remain to be identified. Our results suggest that SPV-1 works through both the Rho-ROCK and calcium signaling pathways to coordinate cellular contractility.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/fisiologia , Sinalização do Cálcio/fisiologia , Proteínas Ativadoras de GTPase/metabolismo , Proteínas Ativadoras de GTPase/fisiologia , Actomiosina/metabolismo , Animais , Caenorhabditis elegans/metabolismo , Cálcio/metabolismo , Proteínas de Ciclo Celular/metabolismo , Embrião não Mamífero/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Contração Muscular/fisiologia , Transdução de Sinais , Proteínas rho de Ligação ao GTP/metabolismo , Quinases Associadas a rho/metabolismo
3.
Semin Cell Dev Biol ; 71: 146-152, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28610943

RESUMO

Many tissues in our body have a tubular shape and are constantly exposed to various stresses. Luminal pressure imposes tension on the epithelial and myoepithelial or smooth muscle cells surrounding the lumen of the tubes. Contractile forces generated by actomyosin assemblies within these cells oppose the luminal pressure and must be calibrated to maintain tube diameter homeostasis and tissue integrity. In this review, we discuss mechanotransduction pathways that can lead from sensation of cell stretch to activation of actomyosin contractility, providing rapid mechanochemical feedback for proper tubular tissue function.


Assuntos
Actomiosina/metabolismo , Células Epiteliais/metabolismo , Homeostase , Animais , Fenômenos Biomecânicos , Humanos , Integrinas/metabolismo , Transdução de Sinais
4.
PLoS Genet ; 12(10): e1006383, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27749909

RESUMO

Cytokinesis in many organisms requires a plasma membrane anchored actomyosin ring, whose contraction facilitates cell division. In yeast and fungi, actomyosin ring constriction is also coordinated with division septum assembly. How the actomyosin ring interacts with the plasma membrane and the plasma membrane-localized septum synthesizing machinery remains poorly understood. In Schizosaccharomyces pombe, an attractive model organism to study cytokinesis, the ß-1,3-glucan synthase Cps1p / Bgs1p, an integral membrane protein, localizes to the plasma membrane overlying the actomyosin ring and is required for primary septum synthesis. Through a high-dosage suppressor screen we identified an essential gene, sbg1+ (suppressor of beta glucan synthase 1), which suppressed the colony formation defect of Bgs1-defective cps1-191 mutant at higher temperatures. Sbg1p, an integral membrane protein, localizes to the cell ends and to the division site. Sbg1p and Bgs1p physically interact and are dependent on each other to localize to the division site. Loss of Sbg1p results in an unstable actomyosin ring that unravels and slides, leading to an inability to deposit a single contiguous division septum and an important reduction of the ß-1,3-glucan proportion in the cell wall, coincident with that observed in the cps1-191 mutant. Sbg1p shows genetic and / or physical interaction with Rga7p, Imp2p, Cdc15p, and Pxl1p, proteins known to be required for actomyosin ring integrity and efficient septum synthesis. This study establishes Sbg1p as a key member of a group of proteins that link the plasma membrane, the actomyosin ring, and the division septum assembly machinery in fission yeast.


Assuntos
Actomiosina/genética , Citocinese/genética , Glucosiltransferases/genética , Proteínas de Membrana/genética , Proteínas de Schizosaccharomyces pombe/genética , Schizosaccharomyces/genética , Citoesqueleto de Actina/genética , Actomiosina/metabolismo , Proteínas de Ciclo Celular/genética , Divisão Celular/genética , Membrana Celular , Parede Celular/genética , Parede Celular/metabolismo , Glucosiltransferases/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , beta-Glucanas/metabolismo
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