The Impact of Gender and Pedagogy on the Development of Self-Regulated Learning Strategies in Undergraduate Engineering Classrooms

The purpose of this paper is to examine ways in which pedagogy and gender of instructor impact the development of self-regulated learning strategies as assessed by the Motivated Strategies for Learning Questionnaire (MSLQ) in male and female undergraduate engineering students. Pedagogy was operationalized as two general formats: lecture plus active learning techniques or problem-base/project-based learning. One hundred seventy-six students from four universities participated in the study. Within-group analyses found significant differences with regard to pedagogy, instructors’ gender, and student gender on the learning strategies and motivation subscales as operationalized by the MSLQ. Male and females students reported significant post-test differences with regard to the gender of instructor and the style of pedagogy. The results of this study showed a pattern where more positive responses for students of both genders were found with the same-gendered instructor. The results also suggested that male students responded more positively to project and problem-based courses with changes evidenced in motivation strategies and resource management. Female students showed decreases in resource management in these two types of courses. Further, female students reported increases in the lecture with active learning courses.

Effect of Classroom Gender Composition on Students' Development of Self-Regulated Learning Competencies

Success in any field depends on a complex interplay among environmental and personal factors. A key set of personal factors for success in academic settings are those associated with self-regulated learners (SRL). Self-regulated learners choose their own goals, select and organize their learning strategies, and self-monitor their effectiveness. Behaviors and attitudes consistent with self-regulated learning also contribute to self-confidence, which may be important for members of underrepresented groups such as women in engineering. This exploratory study, drawing on the concept of "critical mass", examines the relationship between the personal factors that identify a self-regulated learner and the environmental factors related to gender composition of engineering classrooms. Results indicate that a relatively student gender-balanced classroom and gender match between students and their instructors provide for the development of many adaptive SRL behaviors and attitudes.

Pitfalls when examining gap junction hemichannels: interference from volume-regulated anion channels

Human HeLa cells transfected with mouse connexin45 were used to explore the experimental conditions suitable to measure currents carried by gap junction hemichannels. Experiments were performed with a voltage-clamp technique and whole-cell recording. Lowering [Ca(2+)](o) from 2 mM to 20 nM evoked an extra current, I (m), putatively carried by Cx45 hemichannels. However, the variability of I (m) (size, voltage sensitivity, kinetics) suggested the involvement of other channels. The finding that growth medium in the incubator increased the osmolarity with time implied that volume-regulated anion channels (VRAC) may participate. This assumption was reinforced by the following observations. On the one hand, keeping [Ca(2+)](o) normal while the osmolarity of the extracellular solution was reduced from 310 to 290 mOsm yielded a current characteristic of VRAC; I (VRAC) activated/deactivated at negative/positive voltage, giving rise to the conductance functions g (VRAC,inst)=f(V (m)) (inst: instantaneous; V (m): membrane potential) and g (VRAC,ss)=f(V (m)) (ss: steady state). Moreover, it was reversibly inhibited by mibefradil, a Cl(-)channel blocker (binding constant K (d)=38 microM, Hill coefficient n=12), but not by the gap junction channel blocker 18alpha-glycyrrhetinic acid. On the other hand, minimizing the osmotic imbalance while [Ca(2+)](o) was reduced led to a current typical for Cx45 hemichannels; I (hc) activated/deactivated at positive/negative voltage. Furthermore, it was reversibly inhibited by 18alpha-glycyrrhetinic acid or palmitoleic acid, but not by mibefradil. Computations based on g (VRAC,ss)=f(V (m)) and g (hc,ss)=f(V (m)) indicated that the concomitant operation of both currents results in a bell-shaped conductance-voltage relationship. The functional implications of the data presented are discussed. Conceivably, VRAC and hemichannels are involved in a common signaling pathway.

Hint2, a mitochondrial apoptotic sensitizer down-regulated in hepatocellular carcinoma

BACKGROUND ; AIMS: Hints, histidine triad nucleotide-binding proteins, are adenosine monophosphate-lysine hydrolases of uncertain biological function. Here we report the characterization of human Hint2. METHODS: Tissue distribution was determined by real-time quantitative polymerase chain reaction and immunoblotting, cellular localization by immunocytochemistry, and transfection with green fluorescent protein constructs. Enzymatic activities for protein kinase C and adenosine phosphoramidase in the presence of Hint2 were measured. HepG2 cell lines with Hint2 overexpressed or knocked down were established. Apoptosis was assessed by immunoblotting for caspases and by flow cytometry. Tumor growth was measured in SCID mice. Expression in human tumors was investigated by microarrays. RESULTS: Hint2 was predominantly expressed in liver and pancreas. Hint2 was localized in mitochondria. Hint2 hydrolyzed adenosine monophosphate linked to an amino group (AMP-pNA; k(cat):0.0223 s(-1); Km:128 micromol/L). Exposed to apoptotic stress, fewer HepG2 cells overexpressing Hint2 remained viable (32.2 +/- 0.6% vs 57.7 +/- 4.6%), and more cells displayed changes of the mitochondrial membrane potential (87.8 +/- 2.35 vs 49.7 +/- 1.6%) with more cleaved caspases than control cells. The opposite was observed in HepG2 cells with knockdown expression of Hint2. Subcutaneous injection of HepG2 cells overexpressing Hint2 in SCID mice resulted in smaller tumors (0.32 +/- 0.13 g vs 0.85 +/- 0.35 g). Microarray analyses revealed that HINT2 messenger RNA is downregulated in hepatocellular carcinomas (-0.42 +/- 0.58 log2 vs -0.11 +/- 0.28 log2). Low abundance of HINT2 messenger RNA was associated with poor survival. CONCLUSION: Hint2 defines a novel class of mitochondrial apoptotic sensitizers down-regulated in hepatocellular carcinoma.

Function of liver activation-regulated chemokine/CC chemokine ligand 20 is differently affected by cathepsin B and cathepsin D processing

Chemokine processing by proteases is emerging as an important regulatory mechanism of leukocyte functions and possibly also of cancer progression. We screened a large panel of chemokines for degradation by cathepsins B and D, two proteases involved in tumor progression. Among the few substrates processed by both proteases, we focused on CCL20, the unique chemokine ligand of CCR6 that is expressed on immature dendritic cells and subtypes of memory lymphocytes. Analysis of the cleavage sites demonstrate that cathepsin B specifically cleaves off four C-terminally located amino acids and generates a CCL20(1-66) isoform with full functional activity. By contrast, cathepsin D totally inactivates the chemotactic potency of CCL20 by generating CCL20(1-55), CCL20(1-52), and a 12-aa C-terminal peptide CCL20(59-70). Proteolytic cleavage of CCL20 occurs also with chemokine bound to glycosaminoglycans. In addition, we characterized human melanoma cells as a novel CCL20 source and as cathepsin producers. CCL20 production was up-regulated by IL-1alpha and TNF-alpha in all cell lines tested, and in human metastatic melanoma cells. Whereas cathepsin D is secreted in the extracellular milieu, cathepsin B activity is confined to cytosol and cellular membranes. Our studies suggest that CCL20 processing in the extracellular environment of melanoma cells is exclusively mediated by cathepsin D. Thus, we propose a model where cathepsin D inactivates CCL20 and possibly prevents the establishment of an effective antitumoral immune response in melanomas.

The death-associated protein kinase 2 is up-regulated during normal myeloid differentiation and enhances neutrophil maturation in myeloid leukemic cells

The death-associated protein kinase 2 (DAPK2) belongs to a family of Ca(2+)/calmodulin-regulated serine/threonine kinases involved in apoptosis. During investigation of candidate genes operative in granulopoiesis, we identified DAPK2 as highly expressed. Subsequent investigations demonstrated particularly high DAPK2 expression in normal granulocytes compared with monocytes/macrophages and CD34(+) progenitor cells. Moreover, significantly increased DAPK2 mRNA levels were seen when cord blood CD34(+) cells were induced to differentiate toward neutrophils in tissue culture. In addition, all-trans retinoic acid (ATRA)-induced neutrophil differentiation of two leukemic cell lines, NB4 and U937, revealed significantly higher DAPK2 mRNA expression paralleled by protein induction. In contrast, during differentiation of CD34(+) and U937 cells toward monocytes/macrophages, DAPK2 mRNA levels remained low. In primary leukemia, low expression of DAPK2 was seen in acute myeloid leukemia samples, whereas chronic myeloid leukemia samples in chronic phase showed intermediate expression levels. Lentiviral vector-mediated expression of DAPK2 in NB4 cells enhanced, whereas small interfering RNA-mediated DAPK2 knockdown reduced ATRA-induced granulocytic differentiation, as evidenced by morphology and neutrophil stage-specific maturation genes, such as CD11b, G-CSF receptor, C/EBPepsilon, and lactoferrin. In summary, our findings implicate a role for DAPK2 in granulocyte maturation.

Biosynthesis and expression of VE-cadherin is regulated by the PI3K/mTOR signaling pathway

Vascular endothelial (VE)-cadherin is an essential protein of adherens junctions of endothelial cells and plays a pivotal role in vascular homeostasis. Mammalian target of rapamycin complex 2 (mTORC2) deficient mice display defects in fetal vascular development. Blocking mTOR or the upstream kinase phosphoinositide 3-kinase (PI3K) led to a dose-dependently decrease of the VE-cadherin mRNA and protein expression. Immunofluorescent staining showed a strongly decreased expression of VE-cadherin at the interface of human umbilical endothelial cells (HUVECs) followed by intercellular gap formation. Herewith, we demonstrated that the expression of VE-cadherin is dependent on mTOR and PI3K signaling.

Sphingosine kinase-1 is a hypoxia-regulated gene that stimulates migration of human endothelial cells

Sphingosine kinases (SK) catalyze the production of sphingosine-1-phosphate which in turn regulates cell responses such as proliferation and migration. Here, we show that exposure of the human endothelial cell line EA.hy 926 to hypoxia stimulates a increased SK-1, but not SK-2, mRNA, protein expression, and activity. This effect was due to stimulated SK-1 promoter activity which contains two putative hypoxia-inducible factor-responsive-elements (HRE). By deletion of one of the two HREs, hypoxia-induced promoter activation was abrogated. Furthermore, hypoxia upregulated the expression of HIF-1alpha and HIF-2alpha, and both contributed to SK-1 gene transcription as shown by selective depletion of HIF-1alpha or HIF-2alpha by siRNA. The hypoxia-stimulated SK-1 upregulation was functionally coupled to increased migration since the selective depletion of SK-1, but not of SK-2, by siRNAs abolished the migratory response. In summary, these data show that hypoxia upregulates SK-1 activity and results in an accelerated migratory capacity of endothelial cells. SK-1 may thus serve as an attractive therapeutic target to treat diseases associated with increased endothelial migration and angiogenesis such as cancer growth and progression.

Mechano-regulated tenascin-C orchestrates muscle repair

Tenascin-C (TNC) is a mechano-regulated, morphogenic, extracellular matrix protein that is associated with tissue remodeling. The physiological role of TNC remains unclear because transgenic mice engineered for a TNC deficiency, via a defect in TNC secretion, show no major pathologies. We hypothesized that TNC-deficient mice would demonstrate defects in the repair of damaged leg muscles, which would be of functional significance because this tissue is subjected to frequent cycles of mechanical damage and regeneration. TNC-deficient mice demonstrated a blunted expression of the large TNC isoform and a selective atrophy of fast-muscle fibers associated with a defective, fast myogenic expression response to a damaging mechanical challenge. Transcript profiling mapped a set of de-adhesion, angiogenesis, and wound healing regulators as TNC expression targets in striated muscle. Expression of these regulators correlated with the residual expression of a damage-related 200-kDa protein, which resembled the small TNC isoform. Somatic knockin of TNC in fast-muscle fibers confirmed the activation of a complex expression program of interstitial and slow myofiber repair by myofiber-derived TNC. The results presented here show that a TNC-orchestrated molecular pathway integrates muscle repair into the load-dependent control of the striated muscle phenotype.

Regulated catalysis of extracellular nucleotides by vascular CD39/ENTPD1 is required for liver regeneration

BACKGROUND & AIMS: Little is known about how endothelial cells respond to injury, regulate hepatocyte turnover and reconstitute the hepatic vasculature. We aimed to determine the effects of the vascular ectonucleotidase CD39 on sinusoidal endothelial cell responses following partial hepatectomy and to dissect purinergic and growth factor interactions in this model. METHODS: Parameters of liver injury and regeneration, as well as the kinetics of hepatocellular and sinusoidal endothelial cell proliferation, were assessed following partial hepatectomy in mice that do not express CD39, that do not express ATP/UTP receptor P2Y2, and in controls. The effects of extracellular ATP on vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and interleukin-6 responses were determined in vivo and in vitro. Phosphorylation of the endothelial VEGF receptor in response to extracellular nucleotides and growth factors was assessed in vitro. RESULTS: After partial hepatectomy, expression of the vascular ectonucleotidase CD39 increased on sinusoidal endothelial cells. Targeted disruption of CD39 impaired hepatocellular regeneration, reduced angiogenesis, and increased hepatic injury, resulting in pronounced vascular endothelial apoptosis, and decreased survival. Decreased HGF release by sinusoidal endothelial cells, despite high levels of VEGF, reduced paracrine stimulation of hepatocytes. Failure of VEGF receptor-2/KDR transactivation by extracellular nucleotides on CD39-null endothelial cells was associated with P2Y2 receptor desensitization. CONCLUSIONS: Regulated phosphohydrolysis of extracellular nucleotides by CD39 coordinates both hepatocyte and endothelial cell proliferation following partial hepatectomy. Lack of CD39 activity is associated with decreased hepatic regeneration and failure of vascular reconstitution.

TRPC1 is regulated by caveolin-1 and is involved in oxidized LDL-induced apoptosis of vascular smooth muscle cells

Oxidized low-density lipoprotein (oxLDL) induced-apoptosis of vascular cells may participate in plaque instability and rupture. We have previously shown that vascular smooth muscle cells (VSMC) stably expressing caveolin-1 were more susceptible to oxLDL-induced apoptosis than VSMC expressing lower level of caveolin-1, and this was correlated with enhanced Ca(2+) entry and pro-apoptotic events. In this study we aimed to identify the molecular events involved in oxLDL-induced Ca(2+) influx and their regulation by the structural protein caveolin-1. In VSMC, transient receptor potential canonical-1 (TRPC1) silencing by ARN interference, prevents the Ca(2+) influx and reduces the toxicity induced by oxLDL. Moreover, caveolin-1 silencing induces concomitant decrease of TRPC1 expression and reduces oxLDL-induced-apoptosis of VSMC. OxLDL enhanced the cell surface expression of TRPC1, as shown by biotinylation of cell surface proteins, and induced TRPC1 translocation into caveolar compartment, as assessed by subcellular fractionation. OxLDL-induced TRPC1 translocation was dependent on actin cytoskeleton and associated with a dramatic rise of 7-ketocholesterol (a major oxysterol in oxLDL) into caveolar membranes, whereas the caveolar content of cholesterol was unchanged. Altogether, the reported results show that TRPC1 channels play a role in Ca(2+) influx and Ca(2+) homeostasis deregulation that mediate apoptosis induced by oxLDL. These data also shed new light on the role of caveolin-1 and caveolar compartment as important regulators of TRPC1 trafficking to the plasma membrane and apoptotic processes that play a major role in atherosclerosis.

miR-15a and miR-16 are implicated in cell cycle regulation in a Rb-dependent manner and are frequently deleted or down-regulated in non-small cell lung cancer

MicroRNAs (miRNA) are negative regulators of gene expression at the posttranscriptional level, which are involved in tumorigenesis. Two miRNAs, miR-15a and miR-16, which are located at chromosome 13q14, have been implicated in cell cycle control and apoptosis, but little information is available about their role in solid tumors. To address this question, we established a protocol to quantify miRNAs from laser capture microdissected tissues. Here, we show that miR-15a/miR-16 are frequently deleted or down-regulated in squamous cell carcinomas and adenocarcinomas of the lung. In these tumors, expression of miR-15a/miR-16 inversely correlates with the expression of cyclin D1. In non-small cell lung cancer (NSCLC) cell lines, cyclins D1, D2, and E1 are directly regulated by physiologic concentrations of miR-15a/miR-16. Consistent with these results, overexpression of these miRNAs induces cell cycle arrest in G(1)-G(0). Interestingly, H2009 cells lacking Rb are resistant to miR-15a/miR-16-induced cell cycle arrest, whereas reintroduction of functional Rb resensitizes these cells to miRNA activity. In contrast, down-regulation of Rb in A549 cells by RNA interference confers resistance to these miRNAs. Thus, cell cycle arrest induced by these miRNAs depends on the expression of Rb, confirming that G(1) cyclins are major targets of miR-15a/miR-16 in NSCLC. Our results indicate that miR-15a/miR-16 are implicated in cell cycle control and likely contribute to the tumorigenesis of NSCLC.