Multi-lineage differentiation of mesenchymal stem cells – To Wnt,or not Wnt

Mesenchymal stem cells (MSCs) are multipotent precursor cells originating from several adult connective tissues. MSCs possess the ability to self-renew and differentiate into several lineages, and are recognized by the expression of unique cell surface markers. Several lines of evidence suggest that various signal transduction pathways and their interplay regulate MSC differentiation. To that end, a critical player in regulating MSC differentiation is a group of proteins encoded by the Wnt gene family, which was previously known for influencing various stages of embryonic development and cell fate determination. As MSCs have gained significant clinical attention for their potential applications in regenerative medicine, it is imperative to unravel the mechanisms by which molecular regulators control differentiation of MSCs for designing cell-based therapeutics. It is rather coincidental that the functional outcome(s) of Wnt-induced signals share similarities with cellular redox-mediated networks from the standpoint of MSC biology. Furthermore, there is evidence for a crosstalk between Wnt and redox signalling, which begs the question whether Wnt-mediated differentiation signals involve the intermediary role of reactive oxygen species. In this review, we summarize the impact of Wnt signalling on multi-lineage differentiation of MSCs, and attempt to unravel the intricate interplay between Wnt and redox signals.     

Effects of the isothiocyanate sulforaphane on TGF-β1-induced rat cardiac fibroblast activation and extracellular matrix interactions

An important step in many pathological conditions, particularly tissue and organ fibrosis, is the conversion of relatively quiescent cells into active myofibroblasts. These are highly specialized cells that participate in normal wound healing but also contribute to pathogenesis. These cells possess characteristics of smooth muscle cells and fibroblasts, have enhanced synthetic activity secreting abundant extracellular matrix components, cytokines, and growth factors, and are capable of generating contractile force. As such, these cells have become potential therapeutic targets in a number of disease settings. Transforming growth factor β (TGF-β) is a potent stimulus of fibrosis and myofibroblast formation and likewise is an important therapeutic target in several disease conditions. The plant-derived isothiocyanate sulforaphane has been shown to have protective effects in several pathological models including diabetic cardiomyopathy, carcinogenesis, and fibrosis. These studies suggest that sulforaphane may be an attractive preventive agent against disease progression, particularly in conditions involving alterations of the extracellular matrix and activation of myofibroblasts. However, few studies have evaluated the effects of sulforaphane on cardiac fibroblast activation and their interactions with the extracellular matrix. The present studies were carried out to determine the potential effects of sulforaphane on the conversion of quiescent cardiac fibroblasts to an activated myofibroblast phenotype and associated alterations in signaling, expression of extracellular matrix receptors, and cellular physiology following stimulation with TGF-β1. These studies demonstrate that sulforaphane attenuates TGF-β1-induced myofibroblast formation and contractile activity. Sulforaphane also reduces expression of collagen-binding integrins and inhibits canonical and noncanonical TGF-β signaling pathways.     

C1q/tumor necrosis factor-related protein-3 improves renal fibrosis via inhibiting notch signaling pathways

C1q/tumor necrosis factor-related protein-3 (CTRP3) has been extensively reported as an important role involved in antifibrosis, antiapoptosis, and anti-inflammation. However, the role of CTRP3 involved in renal fibrosis remains unclear. Our current study explored the role of CTRP3 in renal fibrosis and its underlying mechanisms by using serums and renal biopsy specimens from renal fibrosis patients and control subjects, rats models with the surgery of unilateral ureteral obstruction (UUO) and human renal proximal tubular epithelial cells (HRPTEpiCs). We found that circulating levels of CTRP3 had no significant difference between renal fibrosis patients and healthy subjects; however, renal CTRP3 expression was markedly downregulated in the fibrotic region with an abundant expression of collagen-I. In UUO rat models, circulating levels of CTRP3 have not changed with the prolonged obstruction of the kidney; renal CTRP3 expression was decreased with the severity of renal fibrosis; adenovirus-mediated CTRP3 treatment inhibited renal interstitial fibrosis. In vitro experiments revealed that CTRP3 attenuates TGF-β1 induced tubular epithelial cells fibrotic changes; CTRP3 knockdown facilitates the expression of fibrotic markers in TGF-β1-induced HRPTEpiCs; recombinant CTRP3 or adenovirus-mediated CTRP3 overexpression significantly inhibited the Notch signaling pathway-associated factors, and knockdown of CTRP3 increased TGF-β1-mediated activation of the Notch signaling pathways. Collectively, our current study found that CTRP3 could improve renal fibrosis, to some extent, through inhibiting the Notch pathway.     

The hormone 17β-estradiol promotes feminization of juveniles protandrous hermaphrodite false clownfish (Amphiprion ocellaris)

The social structure of the false clownfish (Amphiprion ocellaris) typically consists of a pair of functional brooders within a population of individuals which remain as protandrous hermaphrodites usually incapable of breeding. This situation often hampers the commercial scale production of large numbers of clownfish offspring and broodstock. To enhance breeding outputs, protandrous hermaphrodites must be converted to functional brooders with a distinct sex prior to pairing and breeding. In this study, 17β-estradiol (E2) was used to feminize juveniles of A. ocellaris, with groups of fish incubated at 0.1, 0.2, and 0.4 mgL^?1 E2 for 15 days. The gender was substantiated on the basis of gonad histological profiles after 15, 30, and 60 days, work that includes verification of the safety levels of this hormone used in this application. All the treatments employed induced feminization, as shown by histology profiles revealing degenerate male germ cells and testes tissues and several developed ovarian cells at different stages (oogonia, previtellogenic and vitellogenic) 30 days after E2 incubation. Conversely, gonad profiles of non-treated fish did not change. The gonads possessed both ovarian and testicular tissues, a typical characteristic indicating that the fish are still ambisexual. Although E2 was effective in promoting gonad maturation, incubation of fish in high concentrations adversely affected fish survival. Mortalities occurred when E2 exceeded 0.1 mgL^?1. The latter concentration is considered the most appropriate level for inducing feminization and at the same time, maintaining the well-being of the organism.     

A novel acetyltransferase p300 inhibitor ameliorates hypertension-associated cardio-renal fibrosis

Hypertension-associated end-organ damage commonly leads to cardiac and renal fibrosis. As no effective anti-fibrotic therapy currently exists, the unchecked progression of fibrogenesis manifests as cardio-renal failure and early death. We have previously shown that FATp300—p300 with intrinsic factor acetyltransferase activity—is an essential epigenetic regulator of fibrogenesis, and is elevated in several fibrotic tissues. In this report, we investigate the therapeutic efficacy of a novel FATp300 inhibitor, L002, in a murine model of hypertensive cardio-renal fibrosis. Additionally, we examine the effects of L002 on cellular pro-fibrogenic processes and provide mechanistic insights into its antifibrogenic action. Utilizing cardiac fibroblasts, podocytes, and mesangial cells, we demonstrate that L002 blunts FATp300-mediated acetylation of specific histones. Further, incubating cells with L002 suppresses several pro-fibrogenic processes including cellular proliferation, migration, myofibroblast differentiation and collagen synthesis. Importantly, systemic administration of L002 in mice reduces hypertension-associated pathological hypertrophy, cardiac fibrosis and renal fibrosis. The anti-hypertrophic and anti-fibrotic effects of L002 were independent of blood pressure regulation. Our work solidifies the role of epigenetic regulator FATp300 in fibrogenesis and establishes it as a pharmacological target for reducing pathological matrix remodeling and associated pathologies. Additionally, we discover a new therapeutic role of L002, as it ameliorates hypertension-induced cardio-renal fibrosis and antagonizes pro-fibrogenic responses in fibroblasts, podocytes and mesangial cells.     

β-Diketones in Rhododendron waxes

Chromatographic, mass spectrometric and spectroscopic evidence has been obtained for four β-diketones occurring in the leaf waxes of some members of     

The role of tropomyosin domains in cooperative activation of the actin-myosin interaction

To establish α-tropomyosin (Tm)'s structure–function relationships in cooperative regulation of muscle contraction, thin filaments were reconstituted with a variety of Tm mutants (Δ2Tm, Δ3Tm, Δ6Tm, P2sTm, P3sTm, P2P3sTm, P1P5Tm, and wtTm), and force and sliding velocity of the thin filament were studied using an in vitro motility assay. In the case of deletion mutants, Δ indicates which of the quasi-equivalent repeats in Tm was deleted. In the case of period (P) mutants, an Ala cluster was introduced into the indicated period to strengthen the Tm–actin interaction. In P1P5Tm, the N-terminal half of period 5 was substituted with that of period 1 to test the quasi-equivalence of these two Tm periods. The reconstitution included bovine cardiac troponin. Deletion studies revealed that period 3 is important for the positive cooperative effect of Tm on actin filament regulation and that period 2 also contributes to this effect at low ionic strength, but to a lesser degree. Furthermore, Tm with one extra Ala cluster at period 2 (P2s) or period 3 (P3s) did not increase force or velocity, whereas Tm with two extra Ala clusters (P2P3s) increased both force and velocity, demonstrating interaction between these periods. Most mutants did not move in the absence of Ca²⁺. Notable exceptions were Δ6Tm and P1P5Tm, which moved near at the full velocity, but with reduced force, which indicate impaired relaxation. These results are consistent with the mechanism that the Tm–actin interaction cooperatively affects actin to result in generation of greater force and velocity.     

Taking organelles apart, putting them back together and creating new ones: lessons from the endoplasmic reticulum

The endoplasmic reticulum (ER) is a highly dynamic organelle. It is composed of four subcompartments including nuclear envelope (NE), rough ER (rER), smooth ER (sER) and transitional ER (tER). The subcompartments are interconnected, can fragment and dissociate and are able to reassemble again. They coordinate with cell function by way of protein regulators in the surrounding cytosol. The activity of the many associated molecular machines of the ER as well as the fluid nature of the limiting membrane of the ER contribute extensively to the dynamics of the ER. This review examines the properties of the ER that permit its isolation and purification and the physiological conditions that permit reconstitution both in vitro and in vivo in normal and in disease conditions.     

Glutamate antagonism fails to reverse mitochondrial dysfunction in late phase of experimental neonatal asphyxia in rats

Because estrogen plays important neurotrophic and neuroprotective roles in the brain by activating estrogen receptors (ERs), disruption of normal estrogen signaling can leave neurons vulnerable to a variety of insults, including β-amyloid peptide (Aβ). Aroclor1254 (A1254) belongs to the endocrine-disrupting chemical (EDC) polychlorinated biphenyls and has anti-estrogenic properties. In the present study, we evaluated the effect of A1254 on the protective activity of estrogen against Aβ toxicity in differentiated cholinergic SN56 cells. Aged Aβ25-35 causes apoptotic cell death in differentiated SN56 cells, and the cytotoxic evidences are effectively rescued by estrogen. We found that A1254 abolishes the neuroprotective activity of estrogen against Aβ toxicity, and attenuates the suppressive effect of estrogen on Aβ-induced tau phosphorylation and JNK activation. The effects of A1254 on the neuroprotective effects of estrogen in Aβ toxicity are very similar to the effects of the estrogen receptor antagonist ICI182,780. Thus, exposure to EDCs that have anti-estrogenic activity might interfere with normal estrogen-activated neuroprotective signaling events and leave neurons more vulnerable to dangerous stimuli. Our present results provide new understanding of the mechanisms contributing to the harmful effects of EDCs on the function and viability of neurons, and the possible relevance of EDCs in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease.