Exploring Protein Kinase G Inhibition of Canonical Transient Receptor Potential 6 Channels in the Heart

Maladaptive ventricular remodeling often involves pathologic cardiac hypertrophy and at the molecular level the activation of multiple pathways, including G-protein coupled receptor (GPCR) activation. Stimulation of GPCRs is implicated in the activation of calcium entry through the plasma membrane via canonical transient receptor potential (TRPC) channels. TRPC6, a subtype of TRPC channels, is linked to hypertrophic signaling through the dephosphorylation of the transcription factor nuclear factor of activated T-cells (NFAT) by a phosphatase, calcineurin. Channel activity is regulated in part by protein kinase G (PKG) phosphorylation at two residues (T70 and S322) to suppress channel conductance and associated signaling. The impact of this regulation on pathologic processes in vivo and how phosphorylation results in channel inhibition remain unknown. In this thesis, I hypothesized that TRPC6 phosphorylation by PKG could play an important role in hypertrophic remodeling of the in vivo heart. To test this, we developed a mouse model with cardiac-restricted expression of a phosphomimetic TRPC6 (T70E, S322E). At baseline, these animals are similar to littermate controls, and when subjected to pressure-overload, these mice developed similar responses at the chamber level, though there were some differences in molecular signaling. Thus, while capable of suppressing cellular and molecular hypertrophic signaling in vitro, expression of phosphomimetic TRPC6 was not sufficient to block hypertrophic responses in vivo. Another proposed regulatory mechanism was the interaction of TRPC channels with stromal interacting molecule 1 (Stim1), a resident ER-protein that is involved in store-operated calcium entry. We tested the hypothesis that Stim1 inhibition would blunt the development of pathologic hypertrophy by generating a cardiac-restricted knockdown of Stim1 in a mouse model of heart failure, but it was not protective against the development of hypertrophy. Lastly, we conducted studies in the glomerular podocyte focusing on the ability of PKG to modulate TRPC6 activation and NFAT signaling, a pathological signaling cascade in focal and segmental glomerusclerosis (FSGS). We determined channel conductance and podocyte behavior in the face of PKG signaling. Our results demonstrated the potency of PKG to inhibit pathophysiology (podocyte dysfunction, ie. motility) and blunt TRPC6 hyperactivity linked to FSGS

Relationship of study skills and academic performance in radiographic positioning and radiographic procedures of student during first semester SY 2015-2016

The demographic variable gender was included in the study. A total of 163 students from the College of Medical Radiation Technology were chosen using purposive sampling. The correlational research method was used. An adapted questionnaire was distributed to the students who took radiographic positioning and radiologic procedures during the first semester SY 2015-2016. Statistical measurements used in the study are frequency distribution, percentage, mean, standard deviation, t-test for independent mean, and Pearson Correlation Coefficient. Based from the findings, the following conclusions were drawn: 1) in terms of profile, most of the respondents are female who are taking radiographic positioning and radiologic procedures during the first semester of SY 2015-2016; 2) in terms of study skills, the respondents were very good in their textbook reading, note taking skills, memory skills, test preparation skills and concentration skills while respondents were good in their time management skills; 3) the respondents have very good academic performance in radiologic positioning and radiologic procedures during the first semester of SY 2015-2016; 4) the respondents have the same textbook reading skills, test preparation skills and concentration skills regardless of their gender. The respondents have different note taking skills, memory skills and time management skills according to their gender; 5) in terms of academic performance, the respondents in radiographic positioning and radiologic procedures during the first semester of SY 2015-2016 by gender, female has a higher academic performance than male; 6) textbook reading skills, note taking skills, test preparation skills, concentration skills and time management skills have no relationship with academic performance of the respondents in radiographic positioning and radiologic procedures while memory skills have a positive relationship

The effect of respiratory viruses on immunogenicity and protection induced by a candidate universal influenza vaccine in mice.

Current approaches to influenza control rely on vaccines matched to viruses in circulation. Universal influenza vaccines would offer the advantage of providing broad protection against diverse strains of influenza virus. Candidate universal vaccines are developed using model systems, often testing in naïve animals. Yet the human population is not naïve, having varied immune histories that include exposure to viruses. We studied a candidate universal influenza vaccine (replication deficient adenoviruses expressing the conserved influenza A antigens NP and M2 [A/NP+M2-rAd]) given intranasally, the route previously shown to be most effective. To model recipients exposed to viruses, we used mice given rhinovirus (RV1B), respiratory syncytial virus (RSV-A2), influenza B virus, or influenza A virus before or after universal influenza vaccine. Vaccine performance was assessed by measuring immune responses to NP and M2, and monitoring weight loss and survival following influenza A challenge. Prior influenza A virus infection enhanced the response to the vaccine by priming to conserved influenza A antigens. RSV-A2 or RV1B had no effect on antibody responses to NP and M2 in serum. None of the viruses inhibited the ability of the vaccine to protect against influenza A virus challenge. The study demonstrates that the usefulness of this universal vaccine is not confined to the immunologically naïve and supports possible use in a human population with a varied history of respiratory infections

Pivotal role of cardiomyocyte TGF-β signaling in the murine pathological response to sustained pressure overload

The cardiac pathological response to sustained pressure overload involves myocyte hypertrophy and dysfunction along with interstitial changes such as fibrosis and reduced capillary density. These changes are orchestrated by mechanical forces and factors secreted between cells. One such secreted factor is TGF-β, which is generated by and interacts with multiple cell types. Here we have shown that TGF-β suppression in cardiomyocytes was required to protect against maladaptive remodeling and involved noncanonical (non–Smad-related) signaling. Mouse hearts subjected to pressure overload and treated with a TGF-β–neutralizing Ab had suppressed Smad activation in the interstitium but not in myocytes, and noncanonical (TGF-β–activated kinase 1 [TAK1]) activation remained. Although fibrosis was greatly reduced, chamber dysfunction and dilation persisted. Induced myocyte knockdown of TGF-β type 2 receptor (TβR2) blocked all maladaptive responses, inhibiting myocyte and interstitial Smad and TAK1. Myocyte knockdown of TβR1 suppressed myocyte but not interstitial Smad, nor TAK1, modestly reducing fibrosis without improving chamber function or hypertrophy. Only TβR2 knockdown preserved capillary density after pressure overload, enhancing BMP7, a regulator of the endothelial-mesenchymal transition. BMP7 enhancement also was coupled to TAK1 suppression. Thus, myocyte targeting is required to modulate TGF-β in hearts subjected to pressure overload, with noncanonical pathways predominantly affecting the maladaptive hypertrophy/dysfunction