ROCK1 expression is regulated by TGFbeta3 and ALK2 during valvuloseptal endocardial cushion formation

Diagnostic molecular markers predicting aggressive potential in low-grade prostate cancer

Currently, clinicians rely on clinical nomograms to stratify progression risk at the time of diagnosis in patients with prostate cancer (CaP). However, these tools may not accurately distinguish aggressive potential in low-grade CaP. The current study determined the diagnostic potential of 3 molecular markers (ROCK1, RUNX3, and miR-301a) in terms of their ability to identify which low-grade tumors are likely to progress. Real-time PCR and immunohistochemical analysis were used to assess ROCK1, RUNX3, and miR-301a expression profiles in 118 serum and needle biopsy specimens. Expressions of ROCK1 and miR-301a were found to be significantly higher in Gleason 6 and 7 CaP as compared to BPH, while an inverse trend was observed with RUNX3. Further, incorporation of all 3 molecular markers significantly improved clinical nomograms' diagnostic accuracy and correlated with disease progression. Hence, in conclusion, the inclusion of these 3 molecular markers identified aggressive phenotype and predicted disease progression in low-grade CaP tumors at the time of diagnosis.

Sucrose Nonfermenting-Related Kinase Enzyme-Mediated Rho-Associated Kinase Signaling is Responsible for Cardiac Function

BACKGROUND

Cardiac metabolism is critical for the functioning of the heart, and disturbance in this homeostasis is likely to influence cardiac disorders or cardiomyopathy. Our laboratory has previously shown that SNRK (sucrose nonfermenting related kinase) enzyme, which belongs to the AMPK (adenosine monophosphate-activated kinase) family, was essential for cardiac metabolism in mammals. Snrk global homozygous knockout (KO) mice die at postnatal day 0, and conditional deletion of Snrk in cardiomyocytes (Snrk cmcKO) leads to cardiac failure and death by 8 to 10 months.

METHODS AND RESULTS

We performed additional cardiac functional studies using echocardiography and identified further cardiac functional deficits in Snrk cmcKO mice. Nuclear magnetic resonance-based metabolomics analysis identified key metabolic pathway deficits in SNRK knockdown cardiomyocytes in vitro. Specifically, metabolites involved in lipid metabolism and oxidative phosphorylation are altered, and perturbations in these pathways can result in cardiac function deficits and heart failure. A phosphopeptide-based proteomic screen identified ROCK (Rho-associated kinase) as a putative substrate for SNRK, and mass spec-based fragment analysis confirmed key amino acid residues on ROCK that are phosphorylated by SNRK. Western blot analysis on heart lysates from Snrk cmcKO adult mice and SNRK knockdown cardiomyocytes showed increased ROCK activity. In addition, in vivo inhibition of ROCK partially rescued the in vivo Snrk cmcKO cardiac function deficits.

CONCLUSIONS

Collectively, our data suggest that SNRK in cardiomyocytes is responsible for maintaining cardiac metabolic homeostasis, which is mediated in part by ROCK, and alteration of this homeostasis influences cardiac function in the adult heart.

Activin-A in diabetes-induced cardiac malformations in embryos

BACKGROUND

Heart defects are the most common abnormalities in infants of diabetic mothers. Cardiac malformation is associated with altered expression of the genes in the transforming growth factor β system, including inhibin βA, which forms activin-A as a homodimer and functions through its effectors, Smad2 and Smad3. This study aimed to investigate the role of activin-A in diabetes-induced cardiac malformations.

METHODS

Diabetes mellitus in female mice (C57BL/6J) was induced via intravenous injection of streptozotocin. The expression of inhibin βA protein and phosphorylation of Smad2 and Smad3 in the embryonic hearts were examined using immunohistochemical, in situ proximity ligation, and immunoblot assays. Embryos and endocardial cushions of nondiabetic mice were cultured in a high concentration of glucose and treated with activin-A. Mitosis was examined using BrdU incorporation assay and immunohistochemistry of phosphorylated histone H3. Migration of the endocardial cells was assessed using a collagen-based cell migration assay.

RESULTS

The levels of inhibin βA expression and Smad2 and Smad3 activation were significantly reduced by maternal diabetes. Treatment with activin-A significantly increased cell proliferation in the myocardium and migration of endocardial cells, compared with those in vehicle-treated high glucose group, to the level in the euglycemic control group.

CONCLUSIONS

Maternal diabetes suppresses the expression of inhibin βA protein, as well as the activation of Smad2 and Smad3. Activin-A rescues cell proliferation in the myocardium and migration of the endocardial cells suppressed by hyperglycemia. The activin-Smad2/3 signaling system appears to play a role in cardiac malformation in diabetic embryopathy.

Endoplasmic reticulum stress in maternal diabetes-induced cardiac malformations during critical cardiogenesis period

BACKGROUND

Cardiac abnormalities, including atrioventricular (AV) septal defects (AVSDs), are the most common birth defects in diabetic embryopathy. The AV septum is derived from the endocardial cushions, which undergo development and remodeling during septation. The impact of maternal diabetes on these processes needs to be identified. Maternal diabetes disturbs the function of the endoplasmic reticulum (ER). The role of ER stress in cardiac malformation remains to be delineated to gain information for developing therapy.

METHODS

Female mice were induced diabetic via intravenous injection of streptozotocin. Pregnant mice were made hyperglycemic at desired embryonic (E) days. AVSDs were examined histologically at E15.5. ER stress-associated factors were examined and quantified using immunohistochemical and immunoblot assays at E10.5. The role of ER stress in endocardial cell migration was investigated by treating endocardial cushion explants that were cultured in high glucose with an organic chaperone molecule, sodium 4-phenylbutyrate.

RESULTS

The rate of AVSDs in the embryos that were exposed to maternal hyperglycemia during the period of endocardial cushion development was significantly higher than that in those during endocardial cushion remodeling. ER stress was increased in the hearts. Amelioration of ER stress restored endocardial cell migration under hyperglycemic conditions.

CONCLUSIONS

The development, rather than remodeling, of the endocardial cushions is the cardiomorphogenic process that is susceptible to the insult of maternal hyperglycemia in the formation of AVSDs. Maternal diabetes increases ER stress in the developing heart. ER stress plays an essential role in mediating the effect of hyperglycemia on endocardial cell migration.

Nodal signal is required for morphogenetic movements of epiblast layer in the pre-streak chick blastoderm

During axis formation in amniotes, posterior and lateral epiblast cells in the area pellucida undergo a counter-rotating movement along the midline to form primitive streak (Polonaise movements). Using chick blastoderms, we investigated the signaling involved in this cellular movement in epithelial-epiblast. In cultured posterior blastoderm explants from stage X to XI embryos, either Lefty1 or Cerberus-S inhibited initial migration of the explants on chamber slides. In vivo analysis showed that inhibition of Nodal signaling by Lefty1 affected the movement of DiI-marked epiblast cells prior to the formation of primitive streak. In Lefty1-treated embryos without a primitive streak, Brachyury expression showed a patchy distribution. However, SU5402 did not affect the movement of DiI-marked epiblast cells. Multi-cellular rosette, which is thought to be involved in epithelial morphogenesis, was found predominantly in the posterior half of the epiblast, and Lefty1 inhibited the formation of rosettes. Three-dimensional reconstruction showed two types of rosette, one with a protruding cell, the other with a ventral hollow. Our results suggest that Nodal signaling may have a pivotal role in the morphogenetic movements of epithelial epiblast including Polonaise movements and formation of multi-cellular rosette.

Transcriptomic analysis of cell-free fetal RNA suggests a specific molecular phenotype in trisomy 18

Trisomy 18 is a common human aneuploidy that is associated with significant perinatal mortality. Unlike the well-characterized "critical region" in trisomy 21 (21q22), there is no corresponding region on chromosome 18 associated with its pathogenesis. The high morbidity and mortality of affected individuals has limited extensive investigations. In order to better understand the molecular mechanisms underlying the congenital anomalies observed in this condition, we investigated the in utero gene expression profile of second trimester fetuses affected with trisomy 18. Total RNA was extracted from cell-free amniotic fluid supernatant from aneuploid fetuses and euploid controls matched for gestational age and hybridized to Affymetrix U133 Plus 2.0 arrays. Individual differentially expressed transcripts were obtained by two-tailed t tests. Over-represented functional pathways among these genes were identified with DAVID and Ingenuity(®) Pathways Analysis. Results show that three hundred and fifty-two probe sets representing 251 annotated genes were statistically significantly differentially expressed between trisomy 18 and controls. Only 7 genes (2.8% of the annotated total) were located on chromosome 18, including ROCK1, an up-regulated gene involved in valvuloseptal and endocardial cushion formation. Pathway analysis indicated disrupted function in ion transport, MHCII/T cell mediated immunity, DNA repair, G-protein mediated signaling, kinases, and glycosylation. Significant down-regulation of genes involved in adrenal development was identified, which may explain both the abnormal maternal serum estriols and the pre and postnatal growth restriction in trisomy 18. Comparison of this gene set to one previously generated for trisomy 21 fetuses revealed only six overlapping differentially regulated genes. This study contributes novel information regarding functional developmental gene expression differences in fetuses with trisomy 18.

Growth and differentiation factor 9 (GDF-9) induces epithelial-mesenchymal transition in prostate cancer cells

The role of bone morphogenetic proteins in the progression and metastasis of prostate cancer is a topic that has undergone extensive research. This study investigates the role of BMP member growth and differentiation factor 9 (GDF-9) in the progression of this disease. GDF-9 was over-expressed and knocked-down in PC-3 cells, respectively. Furthermore, along with the use of a generated recombinant GDF-9 protein, these cells were then analyzed for any changes in their invasiveness and expression of epithelial-mesenchymal transition (EMT) associated genes. GDF-9 was shown to promote the invasiveness of PC-3 cells together with an induction in the expression of genes including SNAI1, RhoC, ROCK-1, and N-cadherin, while reducing levels of E-cadherin. These expression changes are characteristic of the onset of EMT, and resulted in the cells having a more mesenchymal-like morphology. Treating these cells with activin-like kinase-5 (ALK-5) inhibitor, demonstrated that GDF-9 induced up-regulation of these molecules was ALK-5 dependant. This study shows that in PC-3 cells, GDF-9 signaling via ALK-5, can promote cell invasiveness via a complex network of signaling molecules that work together to trigger the process of EMT, and thereby aid in the aggressiveness and progression of prostate cancer cells.

Muscleblind-like 1 is a negative regulator of TGF-beta-dependent epithelial-mesenchymal transition of atrioventricular canal endocardial cells

The development of the valves and septa of the heart depends on the formation and remodeling of endocardial cushions. Here, we report that the alternative splicing regulator muscleblind-like 1 (MBNL1) exhibits a regionally restricted pattern of expression in canal region endocardium and ventricular myocardium during endocardial cushion development in chicken. Knockdown of MBNL1 in atrioventricular explants leads to a transforming growth factor beta-dependent increase in epithelial-mesenchymal transition (EMT) of endocardial cells. This reveals a novel role for MBNL1 during embryonic development, and represents the first evidence that an alternative splicing regulator is a key player in endocardial cushion development.

Developmental pattern of the right atrioventricular septal valve leaflet and tendinous cords

No consensus exists regarding the precise contribution of myocardium and the atrioventricular (AV) cushion mesenchyme to the development of leaflets, tendinous cords (TCs) and papillary muscles. Furthermore, the origin and fate of the myocardium embedded in the immature mesenchyme of the AV cushions at the beginning of AV valvulogenesis is controversial. Some authors have suggested that these cells result from a mesenchyme-to-myocardium transformation. In contrast, other researchers have concluded that they are derived from the myocardial ventricular wall and the interventricular septum (IVS). On the other hand, it has been assumed that the AV mural and septal leaflets have the same pattern of development. However the supporting structures of the two types of leaflets are anatomically different, which could reflect some differences in the pattern of development. We have therefore investigated the morphogenetic processes involved in sculpting and maturation of the right septal leaflet (RSL) and TCs in embryonic and post-hatching chicken hearts. The origin and fate of the myocardium embedded in the immature cushion mesenchyme at the beginning of RSL morphogenesis was also studied. For this purpose, scanning electron microscopic analysis, histological studies and immunohistochemical detection of Nkx2.5 and MEF2C were performed. Our findings indicate that the RSL and TCs present a distinct morphogenetic pattern from that of the mural leaflets. Our results also provide evidence that myocardial recruitment from the IVS, but not mesenchyme-to-myocardium transformation, participates in the development of the muscular region of the TCs adjacent to the IVS.