VGLL3 is a mechanosensitive protein that promotes cardiac fibrosis through liquid-liquid phase separation.

Myofibroblasts cause tissue fibrosis by producing extracellular matrix proteins, such as collagens. Humoral factors like TGF-ß, and matrix stiffness are important for collagen production by myofibroblasts. However, the molecular mechanisms regulating their ability to produce collagen remain poorly characterised. Here, we show that vestigial-like family member 3 (VGLL3) is specifically expressed in myofibroblasts from mouse and human fibrotic hearts and promotes collagen production. Further, substrate stiffness triggers VGLL3 translocation into the nucleus through the integrin ß1-Rho-actin pathway. In the nucleus, VGLL3 undergoes liquid-liquid phase separation via its low-complexity domain and is incorporated into non-paraspeckle NONO condensates containing EWS RNA-binding protein 1 (EWSR1). VGLL3 binds EWSR1 and suppresses miR-29b, which targets collagen mRNA. Consistently, cardiac fibrosis after myocardial infarction is significantly attenuated in Vgll3-deficient mice, with increased miR-29b expression. Overall, our results reveal an unrecognised VGLL3-mediated pathway that controls myofibroblasts' collagen production, representing a novel therapeutic target for tissue fibrosis.

GRK5-mediated inflammation and fibrosis exert cardioprotective effects during the acute phase of myocardial infarction.

During myocardial infarction (MI), cardiac cells at the infarcted area undergo cell death. In response, cardiac myofibroblasts, which are mainly differentiated from resident fibroblasts upon inflammation, produce extracellular matrix proteins such as collagen to fill the damaged areas of the heart to prevent cardiac rupture. In this study, we identified a cardioprotective role of G-protein-coupled receptor kinase 5 (GRK5) in MI. GRK5 expression was found to increase in the mouse heart after MI and was highly expressed in cardiac fibroblasts/myofibroblasts. In fibroblasts/myofibroblasts, GRK5 promoted the expression of inflammation-related genes through nuclear factor-κB activation, leading to an increase in the expression levels of fibrosis-related genes. Bone marrow transfer experiments confirmed that GRK5 in fibroblasts/myofibroblasts, but not in infiltrated macrophages in the infarcted area, is mainly responsible for GRK5-mediated inflammation in infarcted hearts. In addition, inflammation and fibrosis at the infarcted area were significantly suppressed in GRK5 knockout mice, resulting in increased mortality compared with that in wild-type mice. These data indicate that GRK5 in cardiac fibroblasts/myofibroblasts promotes inflammation and fibrosis to ameliorate the damage after MI.

The well-developed actin cytoskeleton and Cthrc1 expression by actin-binding protein drebrin in myofibroblasts promote cardiac and hepatic fibrosis.

Fibrosis is mainly triggered by inflammation in various tissues, such as heart and liver tissues, and eventually leads to their subsequent dysfunction. Fibrosis is characterized by the excessive accumulation of extracellular matrix proteins (e.g., collagens) produced by myofibroblasts. The well-developed actin cytoskeleton of myofibroblasts, one of the main features differentiating them from resident fibroblasts in tissues under inflammatory conditions, contributes to maintaining their ability to produce excessive extracellular matrix proteins. However, the molecular mechanisms via which the actin cytoskeleton promotes the production of fibrosis-related genes in myofibroblasts remain unclear. In this study, we found, via single-cell analysis, that developmentally regulated brain protein (drebrin), an actin-binding protein, was specifically expressed in cardiac myofibroblasts with a well-developed actin cytoskeleton in fibrotic hearts. Moreover, our immunocytochemistry analysis revealed that drebrin promoted actin cytoskeleton formation and myocardin-related transcription factor-serum response factor signaling. Comprehensive single-cell analysis and RNA-Seq revealed that the expression of collagen triple helix repeat containing 1 (Cthrc1), a fibrosis-promoting secreted protein, was regulated by drebrin in cardiac myofibroblasts via myocardin-related transcription factor-serum response factor signaling. Furthermore, we observed the profibrotic effects of drebrin exerted via actin cytoskeleton formation and the Cthrc1 expression regulation by drebrin in liver myofibroblasts (hepatic stellate cells). Importantly, RNA-Seq demonstrated that drebrin expression levels increased in human fibrotic heart and liver tissues. In summary, our results indicated that the well-developed actin cytoskeleton and Cthrc1 expression due to drebrin in myofibroblasts promoted cardiac and hepatic fibrosis, suggesting that drebrin is a therapeutic target molecule for fibrosis.

Enhanced acetic acid and succinic acid production under microaerobic conditions by Corynebacterium glutamicum harboring Escherichia coli transhydrogenase gene pntAB.

Some microorganisms, such as Escherichia coli, harbor transhydrogenases that catalyze the interconversion between NADPH and NADH. However, such transhydrogenase genes have not been found in the genome of a glutamic acid-producing bacterium Corynebacterium glutamicum. In this study, the E. coli transhydrogenase genes udhA and pntAB were introduced into the C. glutamicum wild-type strain ATCC 13032, and the metabolic characteristics of the recombinant strains under aerobic and microaerobic conditions were examined. No major metabolic changes were observed following the introduction of the E. coli transhydrogenase genes under aerobic conditions. Under microaerobic conditions, significant metabolic change was not observed following the introduction of the udhA gene. However, the specific production rates of lactic acid, acetic acid, and succinic acid, and the overall production levels of acetic acid and succinic acid were increased by introducing the E. coli pntAB gene. Moreover, the NADH/NAD(+) ratio was increased by introduction of pntAB. Our results suggest that the E. coli PntAB transhydrogenase enhances the conversion of NADPH to NADH in C. glutamicum under microaerobic conditions, and the increased NADH/NAD(+) ratio results in increased succinic acid production. In addition, acetic acid production might be enhanced to supply ATP to the anaplerotic reaction catalyzed by pyruvate carboxylase.

Halarchaeum nitratireducens sp. nov., a moderately acidophilic haloarchaeon isolated from commercial sea salt.

Two halophilic moderately acidophilic archaeal strains, MH1-136-2(T) and MH1-370-1 were isolated from commercial salt samples made from seawater in Japan and Indonesia, respectively. Cells of the two strains were pleomorphic and Gram-stain-negative. Strain MH1-136-2(T) was pink pigmented, while MH1-370-1 was orange-red pigmented. Strain MH1-136-2(T) was able to grow at 9-30 % (w/v) NaCl (with optimum, 21 % NaCl, w/v) at pH 4.5-6.2 (optimum, pH 5.2-5.5) and at 18-55 °C (optimum, 45 °C). Strain MH1-370-1 was able to grow at 12-30 % (w/v) NaCl (optimum, 18 %, w/v) at pH 4.2-6.0 (optimum, pH 5.2-5.5) and 20-50 °C (optimum, 45 °C). Strain MH1-136-2(T) required at least 1 mM Mg(2+), while MH1-370-1 required at least 10 mM for growth. Both strains reduced nitrate and nitrite under aerobic conditions. The 16S rRNA gene sequences of strains MH1-136-2(T) and MH1-370-1 were identical, and the closest relative was Halarchaeum rubridurum MH1-16-3(T) with 98.3 % similarity. The level of DNA-DNA relatedness between these strains was 90.9 % and 92.4 % (reciprocally), while that between MH1-136-2(T) and Halarchaeum acidiphilum MH1-52-1(T), Halarchaeum salinum MH1-34-1(T) and Halarchaeum rubridurum MH1-16-3(T) was 37.7 %, 44.3 % and 41.1 % (each an average), respectively. Based on the phenotypic, genotypic and phylogenetic analyses, it is proposed that the isolates represent a novel species of the genus Halarchaeum, for which the name Halarchaeum nitratireducens sp. nov. is proposed. The type strain is MH1-136-2(T) ( = JCM 16331(T) = CECT 7573(T)) isolated from solar salt produced in Japan.

Halarchaeum rubridurum sp. nov., a moderately acidophilic haloarchaeon isolated from commercial sea salt samples.

Six halo-acidophilic archaeal strains were isolated from four commercial salt samples obtained from seawater in the Philippines, Indonesia (Bali) and Japan (Okinawa) on agar plates at pH 4.5. Cells of the six strains were pleomorphic, and stained Gram-negative. Two strains were pink-red pigmented, while four other strains were orange-pink pigmented. Strain MH1-16-3(T) was able to grow at 9-30% (w/v) NaCl [with optimum at 18% (w/v) NaCl], at pH 4.5-6.8 (optimum, pH 5.5) and at 20-50 °C (optimum, 42 °C). The five other strains grew at slightly different ranges. The six strains required at least 1 mM Mg(2+) for growth. The 16S rRNA gene sequences of the six strains were almost identical, sharing 99.9 (1-2 nt differences) to 100% similarity. The closest relatives were Halarchaeum acidiphilum MH1-52-1(T) and Halarchaeum salinum MH1-34-1(T) with 97.7% similarity. The DNA G+C contents of the six strains were 63.2-63.7 mol%. Levels of DNA-DNA relatedness amongst the six strains were 79-86%, while those between MH1-16-3(T) and H. acidiphilum MH1-52-1(T) and H. salinum MH1-34-1(T) were both 43 and 45% (reciprocally), respectively. Based on the phenotypic, genotypic and phylogenetic analyses, it is proposed that the six isolates represent a novel species of the genus Halarchaeum, for which the name Halarchaeum rubridurum sp. nov. is proposed. The type strain is MH1-16-3(T) ( =JCM 16108(T) =CECT 7535(T)).

Halarchaeum salinum sp. nov., a moderately acidophilic haloarchaeon isolated from commercial sea salt.

Three halophilic archaeal strains, MH1-34-1(T), MH1-16-1 and MH1-224-5 were isolated from commercial salt samples produced from seawater in Indonesia, the Philippines and Japan, respectively. Cells of the three strains were pleomorphic and stained Gram-negative. Strain MH1-34-1(T) was orange-red pigmented, while MH1-16-1 and MH1-224-5 were pink-pigmented. Strain MH1-34-1(T) was able to grow at 12-30 % (w/v) NaCl (with optimum at 18 % NaCl, w/v) at pH 4.5-7.2 (optimum, pH 5.2-5.5) and at 15-45 °C (optimum, 42 °C). Strains MH1-16-1 and MH1-224-5 grew in slightly different ranges. These strains required at least 1 mM Mg(2+) for growth. The 16S rRNA gene sequences of strains MH1-34-1(T), MH1-16-1 and MH1-224-5 were almost identical (99.8-99.9 % similarities), and the closest relative was Halarchaeum acidiphilum MH-1-52-1(T) with 98.4 % similarities. The DNA G+C contents of MH1-34-1(T), MH1-16-1 and MH1-224-5 were 59.3, 60.8 and 61.0 mol%, respectively. The level of DNA-DNA relatedness amongst the three strains was 90-91 %, while that between each of the three strains and Halarchaeum acidiphilum MH1-52-1(T) was 51-55 %. Based on the phenotypic, genotypic and phylogenetic analyses, it is proposed that the isolates should represent a novel species of the genus Halarchaeum, for which the name Halarchaeum salinum sp. nov. is proposed. The type strain is MH1-34-1(T) ( = JCM 16330(T) = CECT 7574(T)).