Members Of Protein Kinase Research Articles

Targeting MELK in tumor cells and tumor microenvironment: from function and mechanism to therapeutic application.

Maternal embryonic leucine zipper kinase (MELK), a member of the adenosine monophosphate-activated protein kinase (AMPK) protein family, has been reported to be involved in the regulation of many cellular events. The aberrant expression of MELK is associated with tumorigenesis and malignant progression of various tumors. Moreover, MELK plays an essential role in the regulation of tumor microenvironment (TME), which affects the function of immune cells and the responsiveness to immunotherapy. Currently, small molecule inhibitors targeting MELK have been developed and evaluated in clinical trials. A comprehensive understanding of MELK may provide clues and confidence for subsequent basic research and scientific transformation. In this review, we provide a comprehensive overview of the structural features, molecular biological functions, and critical roles of MELK in tumors and TME, as well as the targeted agents under development for the treatment of tumors and discuss the perspective for MELK-targeted therapies for tumors.

Kaempferol Suppresses Carbon Tetrachloride-Induced Liver Damage in Rats via the MAPKs/NF-κB and AMPK/Nrf2 Signaling Pathways.

Oxidative stress plays a critical role in the development of liver disease, making antioxidants a promising therapeutic approach for the prevention and management of liver injuries. The aim of this study was to investigate the hepatoprotective effects of kaempferol, an antioxidant flavonoid found in various edible vegetables, and its underlying mechanism in male Sprague-Dawley rats with carbon tetrachloride (CCl4)-induced acute liver damage. Oral administration of kaempferol at doses of 5 and 10 mg/kg body weight resulted in the amelioration of CCl4-induced abnormalities in hepatic histology and serum parameters. Additionally, kaempferol decreased the levels of pro-inflammatory mediators, TNF-α and IL-1β, as well as COX-2 and iNOS. Furthermore, kaempferol suppressed nuclear factor-kappa B (NF-κB) p65 activation, as well as the phosphorylation of Akt and mitogen-activated protein kinase members (MAPKs), including extracellular signal-regulated kinase, c-Jun NH2-terminal kinase, and p38 in CCl4-intoxicated rats. In addition, kaempferol improved the imbalanced oxidative status, as evidenced by the reduction in reactive oxygen species levels and lipid peroxidation, along with increased glutathione content in the CCl4-treated rat liver. Administering kaempferol also enhanced the activation of nuclear factor-E2-related factor (Nrf2) and heme oxygenase-1 protein, as well as the phosphorylation of AMP-activated protein kinase (AMPK). Overall, these findings suggest that kaempferol exhibits antioxidative, anti-inflammatory, and hepatoprotective effects through inhibiting the MAPK/NF-κB signaling pathway and activating the AMPK/Nrf2 signaling pathway in CCl4-intoxicated rats.

Activation of PKCβII through nuclear trafficking guided by βγ subunits of trimeric G protein and 14-3-3ε

AimsConventional members of protein kinase C (PKC) family, including PKCβII, are constitutively phosphorylated on three major motifs and located in the cytosol in a primed state. In response to cellular stimuli, PKCβII is activated through inducible phosphorylation and Mdm2-mediated ubiquitination. In this study, we aimed to identify the activation mechanism of PKCβII, focusing on the signaling cascade that regulate the phosphorylation and ubiquitination. Materials and methodsLoss-of-function approaches and mutants of PDK1/PKCβII that display different regulatory properties were used to identify the cellular components and processes responsible for endocytosis. Key findingsPhorbol 12-myristate 13-acetate (PMA)-induced phosphorylation and ubiquitination of PKCβII, which are needed for its translocation to the plasma membrane, required the presence of both Gβγ and 14-3-3ε. Gβγ and 14-3-3ε mediated the constitutive phosphorylation of PKCβII by scaffolding PI3K and PDK1 in the cytosol, which is an inactive but required state for the activation of PKCβII by subsequent signals. In response to PMA treatment, the signaling complex translocated to the nucleus with dissociation of PI3K from it. Thereafter, PDK1 stably interacted with 14-3-3ε and was dephosphorylated; PKCβII interacted with Mdm2 along with Gβγ, leading to its ubiquitination at two lysine residues on its C-tail. Finally, PDK1/14-3-3ε and ubiquitinated PKCβII translocated to the plasma membrane. SignificanceAs PKCβII mediates a wide range of cellular functions and plays important roles in the pathogenesis of various diseases, our results will provide clues to understand the pathogenesis of PKCβII-related disorders and facilitate their treatment.

Molecular Network Analyses Implicate Death-Associated Protein Kinase 3 (DAPK3) as a Key Factor in Colitis-Associated Dysplasia Progression.

Ulcerative colitis (UC) is a progressive disorder that elevates the risk of colon cancer development through a colitis-dysplasia-carcinoma sequence. Gene expression profiling of colitis-associated lesions obtained from patients with varied extents of UC can be mined to define molecular panels associated with colon cancer development. Differential gene expression profiles of 3 UC clinical subtypes and healthy controls were developed for the GSE47908 microarray data set of healthy controls, left-sided colitis, pancolitis, and colitis-associated dysplasia (CAD) using limma R. A gene ontology enrichment analysis of differentially expressed genes (DEGs) revealed a shift in the transcriptome landscape as UC progressed from left-sided colitis to pancolitis to CAD, from being immune-centric to being cytoskeleton-dependent. Hippo signaling (via Yes-associated protein [YAP]) and Ephrin receptor signaling were the top canonical pathways progressively altered in concert with the pathogenic progression of UC. A molecular interaction network analysis of DEGs in left-sided colitis, pancolitis, and CAD revealed 1 pairwise line, or edge, that was topologically important to the network structure. This edge was found to be highly enriched in actin-based processes, and death-associated protein kinase 3 (DAPK3) was a critical member and sole protein kinase member of this network. Death-associated protein kinase 3 is a regulator of actin-cytoskeleton reorganization that controls proliferation and apoptosis. Differential correlation analyses revealed a negative correlation for DAPK3-YAP in healthy controls that flipped to positive in left-sided colitis. With UC progression to CAD, the DAPK3-YAP correlation grew progressively more positive. In summary, DAPK3 was identified as a candidate gene involved in UC progression to dysplasia.

Promotion of the inflammatory response in mid colon of complement component 3 knockout mice

To determine whether complement component 3 (C3) deficiency affects its receptor downstream-mediated inflammatory response, the current study was undertaken to measure alterations in the inducible nitric oxide synthase (iNOS)‑mediated cyclooxygenase‑2 (COX‑2) induction pathway, inflammasome pathway, nuclear factor-κB (NF-κB) activation, and inflammatory cytokine expressions in the mid colon of C3 knockout (KO) mice. Significant enhancement was observed in expressions of key components of the iNOS‑mediated COX‑2 induction pathway, and in the phosphorylation of mitogen‑activated protein (MAP) kinase members. A similar pattern of increase was also observed in the expression levels of inflammasome proteins in C3 KO mice. Moreover, compared to WT mice, C3 KO mice showed remarkably enhanced phosphorylation of NF-κB and Inhibitor of κB-α (IκB-α), which was reflected in entirety as increased expressions of Tumor necrosis factor (TNF), IL-6 and IL-1α. However, the levels of E-cadherin, tight junction channels and ion channels expressions were lower in the C3 KO mice, although myeloperoxidase (MPO) activity for neutrophils was slightly increased. Taken together, results of the current study indicate that C3 deficiency promotes inflammatory responses in the mid colon of C3 KO mice through activation of the iNOS‑mediated COX‑2 induction pathway, Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)-inflammasome pathway and NF-κB signaling pathway, and the enhancement of inflammatory cytokine expressions.

Anti-inflammation of epicatechin mediated by TMEM35A and TMPO in bovine mammary epithelial cell line cells and mouse mammary gland

Epicatechin (EC) has significant antiinflammation, antioxidation, and anticancer activities. It also provides a new alternative treatment for mastitis, which can result in great economic losses in the dairy industry if left untreated. The purpose of this study was to investigate the anti-inflammatory effects of EC on mastitis and the underlying mechanism using in vivo and in vitro systems. The use of ELISA and immunohistochemistry assays showed that EC treatment at 1.5, 7.5, 15, and 30 mg/mL decreased protein expression of inflammatory mediators, including cyclooxygenase-2 and inducible nitric oxide synthase; inflammatory cytokines, which were composed of IL-1β, TNF-α, and IL-6 in lipopolysaccharide (LPS)-stimulated bovine mammary epithelial cell line (MAC-T); and mouse mammary gland, together with reduced filtration of T lymphocytes in the mouse mammary gland. Furthermore, EC treatment reduced LPS-induced phosphorylation levels of p65 and inhibitor of NF-κB, and blocked nuclear translocation of p65 as revealed by western blot and immunofluorescence test in MAC-T cells and the mouse mammary gland. Epicatechin also attenuated LPS-induced phosphorylation levels of mitogen-activated protein kinase members (i.e., p38, c-Jun N-terminal kinase 1/2 and extracellular regulated protein kinases 1/2). Using RNA-seq and tandem mass tag analyses, upregulation of TMEM35A and TMPO proteins was disclosed in MAC-T cells cotreated with LPS and EC. Although clustered regularly interspaced short palindromic repeats/Cas9-based knockdown of TMEM35A and TMPO attenuated abundance of phosphorylated (p)-p65, p-p38, TNF-α, and iNOS, overexpression of TMEM35A reversed EC-mediated effects in TMPO knockdown cells. Moreover, interaction between TMEM35A and TMPO was detected using the co-immunoprecipitation method. In conclusion, our data demonstrated that EC inhibited LPS-induced inflammatory response in MAC-T cells and the mouse mammary gland. Importantly, TMEM35A mediated the transmembrane transport of EC, and the interaction between TMEM35A and TMPO inhibited MAPK and NF-κB pathways.

Deregulated Protein Kinases: Friend and Foe in Ischemic Stroke

Ischemic stroke is the third leading cause of mortality worldwide, but its medical management is still limited to the use of thrombolytics as a lifesaving option. Multiple molecular deregulations of the protein kinase family occur during the period of ischemia/reperfusion. However, experimental studies have shown that alterations in the expression of essential protein kinases and their pharmacological modulation can modify the neuropathological milieu and hasten neurophysiological recovery. This review highlights the role of key protein kinase members and their implications in the evolution of stroke pathophysiology. Activation of ROCK-, MAPK-, and GSK-3β-mediated pathways following neuronal ischemia/reperfusion injury in experimental conditions aggravate the neuropathology and delays recovery. Targeting ROCK, MAPK, and GSK-3β will potentially enhance myelin regeneration, improve blood-brain barrier (BBB) function, and suppress inflammation, which ameliorates neuronal survival. Conversely, protein kinases such as PKA, Akt, PKCα, PKCε, Trk, and PERK salvage neurons post-ischemia by mechanisms including enhanced toxin metabolism, restoring BBB integrity, neurotrophic effects, and apoptosis suppression. Certain protein kinases such as ERK1/2, JNK, and AMPK have favourable and unfavourable effects in salvaging ischemia-injured neurons. Targeting multiple protein kinase-mediated pathways simultaneously may improve neuronal recovery post-ischemia.

In silico studies of isatinyl-2-aminobenzoylhydrazone transition metal complexes against cyclin-dependent kinase 6 (CDK6)

Cyclin-dependent kinase 6 (CDK6) is an important member of protein kinases, involving in many cellular pathways especialy cell cycle progression. Thus, CDK6 is a promising target in cancer therapy. This report aims to predict inhibiton of CDK6 by some complex compounds by using molecular docking and pharmacological properties analysis. Those compounds are isatinyl-2-aminobenzoylhydrazone (ISABH) and cobalt (II), nickel (II), copper (II), and zinc (II) transition metal complexes. The molecular docking against CDK6 (PDB code: 3NUP) revealed that ISABH/ISABH-transition metal complexes established ligand-protein interaction as expressed by negative binding affinity values. Drug-likeness by SwissADME indicated that ISABH and Ni-ISABH met the Lipinski’s rule of five. Both compounds also showed reasonable pharmacological criteria by admetSAR.

Suppression of TopBP1 function increases the efficacy of chemotherapeutic treatments by enhancing the induction of apoptosis

AbstractThe DNA damage response (DDR) is an important mechanism to maintain genome integrity by arresting cell cycle progression and inducing DNA repair and/or apoptosis. Therefore, the activity of DDR is closely related to the drug sensitivity of cancer cells. Inhibitors of ATR, a key member of protein kinases functioning in DDR, are attractive candidates as sensitizers in chemotherapy. In this study, we explore another candidate of chemosensitizers and report DNA topoisomerase II binding protein 1 (TopBP1), a regulator of ATR‐mediated signaling, as a potential target to increase the efficacy of chemotherapeutic treatments. Suppression of TopBP1 using siRNA increased cancer cell sensitivity to cisplatin and an alkylating agent N‐methyl‐N‐nitrosourea (MNU), concomitant with a percentage increase in the sub‐G1 population and caspase‐9 activation. The immunoblotting analysis revealed that the phosphorylation of CHK1 was significantly reduced in TopBP1‐knockdown cells. Consequently, treatment with an ATR inhibitor dramatically increased the production of the sub‐G1 population compared to an ATM inhibitor. Phosphorylation of RPA2 increased after drug treatment in TopBP1‐knockdown cells. These results suggest that TopBP1 is involved in DDR protecting stalled forks from collapse and preventing apoptosis through the activation of an ATR/CHK1 signaling pathway.

Genome-wide survey of sucrose non-fermenting 1-related protein kinase 2 in Rosaceae and expression analysis of PbrSnRK2 in response to ABA stress

BackgroundThe members of the sucrose non-fermenting 1-related protein kinase 2 (SnRK2) family are specific serine/threonine protein kinases in plants that play important roles in stress signal transduction and adaptation. Because of their positive regulatory roles in response to adverse conditions, the genes encoding thes proteins are considered potential candidates for breeding of plants for disease resistance and genetic improvement. However, there is far less information about this kinase family, and the function of these genes has not been explored in Rosaceae.ResultsA genome-wide survey and analysis of the genes encoding members of the SnRK2 family were performed in pear (Pyrus bretschneideri) and seven other Rosaceae species. A total of 71 SnRK2 genes were identified from the eight Rosaceae species and classified into three subgroups based on phylogenetic analysis and structural characteristics. Purifying selection played a crucial role in the evolution of SnRK2 genes, and whole-genome duplication and dispersed duplication were the primary forces underlying the characteristics of the SnRK2 gene family in Rosaceae. Transcriptome data and qRT-PCR assay results revealed that the distribution of PbrSnRK2s was very extensive, including across the roots, leaves, pollen, styles, and flowers, although most of them were mainly expressed in leaves. In addition, under stress conditions, the transcript levels of some of the genes were upregulated in leaves in response to ABA treatment.ConclusionsThis study provides useful information and a theoretical introduction for the study of the evolution, expression, and functions of the SnRK2 gene family in plants.

Overview of Protein Kinase B Enzyme: A Potential Target for Breast and Prostate Cancer.

Protein kinase B (AKT) PI3K / AKT / mTOR signaling pathways play a crucial role in modulating cell survival, proliferation, metastasis, metabolism, angiogenesis, and apoptosis. The AKT family consists of three isoforms: AKT1, AKT2, and AKT3. Moreover, it has high sequence homology in the kinase domain and has similar substrate specificity to other members of AGC protein kinase. Recent studies have shown that AKT signals disappear in some tumors. Overexpression and activation of AKT are not sufficient to induce the phenotype of malignant tumors. However, many studies have shown the importance of AKT in carcinogenesis including, breast and prostate cancers, second and third global cancer burden, respectively, in terms of incidence and death. Inhibition of AKT signaling may be beneficial in terms of therapeutic use and understanding of the function of AKT. To date, limited numbers of AKT inhibitors have been identified, and none are strongly selective for AKT isoforms. In this regard, we discussed the current insight of AKT inhibitors in drug development, protein structure, and mechanism as well as the role of AKT in the development of drug targets for breast cancer and prostate cancer.

Interaction between TaNOX7 and TaCDPK13 Contributes to Plant Fertility and Drought Tolerance by Regulating ROS Production.

Reactive oxygen species (ROS) homeostasis is critical for both physiological processes and stress responses of plants. NADPH oxidases (NOXs) are the key producers of ROS in plants. However, their functions in ROS homeostasis and plant growth regulation in wheat (Triticum aestivum) are little investigated. Here, we cloned and characterized a NOX isoform TaNOX7 in wheat. Overexpression of TaNOX7 in rice led to enhanced root length, ROS production, drought tolerance as well as bigger panicles and higher yield but shorter growth period duration. Further results indicate that TaCDPK13, a member of calcium-dependent protein kinases (CDPKs), can directly interact with TaNOX7 and enhance ROS production in plants. These results demonstrate that TaNOX7 plays crucial roles in wheat development, fertility, and drought tolerance via interaction with TaCDPK13, which may act as an upstream regulator of TaNOX7 to regulate ROS production in wheat.

The calcineurin β-like interacting protein kinase CIPK25 regulates potassium homeostasis under low oxygen in Arabidopsis.

Hypoxic conditions often arise from waterlogging and flooding, affecting several aspects of plant metabolism, including the uptake of nutrients. We identified a member of the CALCINEURIN β-LIKE INTERACTING PROTEIN KINASE (CIPK) family in Arabidopsis, CIPK25, which is induced in the root endodermis under low-oxygen conditions. A cipk25 mutant exhibited higher sensitivity to anoxia in conditions of potassium limitation, suggesting that this kinase is involved in the regulation of potassium uptake. Interestingly, we found that CIPK25 interacts with AKT1, the major inward rectifying potassium channel in Arabidopsis. Under anoxic conditions, cipk25 mutant seedlings were unable to maintain potassium concentrations at wild-type levels, suggesting that CIPK25 likely plays a role in modulating potassium homeostasis under low-oxygen conditions. In addition, cipk25 and akt1 mutants share similar developmental defects under waterlogging, further supporting an interplay between CIPK25 and AKT1.

Circ-016910 sponges miR-574-5p to regulate cell physiology and milk synthesis via MAPK and PI3K/AKT-mTOR pathways in GMECs.

Incremental proofs demonstrate that miRNAs, the essential regulators of gene expression, are implicated in various biological procedures, including mammary development and milk synthesis. Here, the role of miR‐574‐5p in milk synthesis, apoptosis, and proliferation of goat mammary epithelial cells (GMECs) are explored without precedent, and the molecular mechanisms for the impacts are elucidated. Small RNA libraries were constructed using GMECs transfected with miR‐574‐5p mimics and negative control followed by sequencing via Solexa technology. Overall, 332 genes were distinguishingly expressed entre two libraries, with 74 genes upregulated and 258 genes downregulated. This approach revealed mitogen‐activated protein kinase kinase kinase 9 (MAP3K9), an upstream activator of MAPK signaling, as a differentially expressed unigene. miR‐574‐5p targeted seed sequences of the MAP3K9 3′‐untranslated region and suppressed its messenger RNA (mRNA) and protein levels, correspondingly. GMECs with miR‐574‐5p overexpression and MAP3K9 inhibition showed increased cell apoptosis and decreased cell proliferation resulting from sustained suppression of MAPK pathways, while MAP3K9 elevation manifested the opposite results. miR‐574‐5p repressed the phosphorylation of members of protein kinase B (AKT)–mammalian target of rapamycin pathway via downregulating MAP3K9 and AKT3, resulting in reducing the secretion of β‐casein and triglycerides in GMECs. Finally, according to the constructed circular RNA (circRNA) libraries and bioinformatics prediction approach, we selected circ‐016910 and found it acted as a sponge for miR‐574‐5p and blocked its relevant behaviors to undertake biological effects in GMECs. The circRNA–miRNA–mRNA network facilitates further probes on the function of miR‐574‐5p in mammary development and milk synthesis.

2129-P: DAP-Related Apoptosis-Inducing Kinase-2 Negatively Regulate Islet Beta-Cell Function by Autophagy Repression

Islet apoptosis is a detrimental event causing or aggravating type 2 diabetes (T2D). The attenuation of islet β cells is always accompanied by the development of T2D. Current clinical antidiabetic drugs are shown to be effective, but they have not fundamentally solved the essence of islet cellular apoptosis and failure. Therefore, it is necessary to identify novel targets and potential therapeutics for hyperglycemic treatment with significant protection/delay islet function attenuation. DAP-related apoptosis-inducing kinase-2 (Drak2) is a member of death-associated protein kinase (DAPK) family. We found higher expression of Drak2 in pancreas of db/db mice compared with littermites. We demonstrated that Drak2 activity was negatively related with glucose-stimulated insulin secretion (GSIS) and the autophagic flux by knockdown or overexpression of Drak2 in primary islets. To further investigate the role of Drak2 in islet function, we generated β cell-specific Drak2 knockout mice (βKO) model. We found that the capacity of glucose tolerance was enhanced in βKO mice. And Drak2-deficient islets can resistant to palmitate-triggered apoptosis and GSIS impairment. On the other hand, Drak2 inhibitors were applied in the efficacy study, we demonstrated that these compounds effectively protected islets from apoptosis via autophagy promotion in vitro and ameliorated T2D in vivo in mouse models. Mechanistically, Drak2 may be involved in autophagy regulation through autophagy initiation complex, ULK1, to exerting its effects on the function and apoptosis of islet cells. Our preliminary work show that inhibition or deficiency of Drak2 protects β cell from apoptosis may due to autophagy promotion, and suggest that Drak2 might be a novel target for potential diabetic therapeutics development. Disclosure Y. lu: None. J. Li: None. J. Li: None. Funding Shanghai Municipal Science and Technology Commission (16430711700)

Abstract P1-06-03: A selective Cdk12/13 non-covalent inhibitor with potent anti-breast cancer activity

Abstract Cyclin-dependent kinases 12 and 13 (CDK12 and CDK13) are Ser/Thr protein kinase members of the CDK family. CDKs are regulated by cyclins and members of the family are key regulators of the cell cycle. Other members of this family—CDK7, CDK8, CDK9, CDK12 and CDK13—have been described as transcription-regulating kinases. CDK12 and CDK13 phosphorylate the C-terminal domain (CTD) of rpb1 the largest subunit of RNA polymerase II and interact with RNA processing factors, playing pivotal roles controlling transcription initiation and elongation, as well as posttranscriptional RNA processing. Specifically, CDK12 acts as the limiting factor for the transcription of a small subset of genes that are involved in the DNA damage response pathway and CDK13 affects expression of genes involved in growth signaling pathways. Importantly, like their cell cycle family members CDK12 and CDK13 have also been shown to be promising therapeutic targets for several cancer types. We have generated a novel, selective, and orally bioavailable, small molecule inhibitor of CDK12 and CDK13. Our lead molecule downregulates key DNA damage repair proteins including ATM, ATR, Brca1 and Rad51 leading to induction of apoptotic cell death in all triple negative breast cancer (TNBC) cell lines tested. We have confirmed the selectivity of our compound by kinase profiling and by comparing the gene expression profile by RNA-seq of cells treated with compound or infected with CRISPR sgRNA targeting Cdk12 and/or Cdk13. Importantly, our compound acts in synergy with the chemotherapeutic agents Cisplatin, Irinotecan and Olaparib. Finally, in preclinical efficacy studies, our lead compound blocked tumor progression in two different PDX models of TNBC and demonstrated tumor regression and enhanced efficacy over single treatment when dosed in combination with selected chemotherapeutic agents. Citation Format: Quereda V, Bayle S, Francesca V, Andrii M, William R, Derek D. A selective Cdk12/13 non-covalent inhibitor with potent anti-breast cancer activity [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-06-03.

Low-intensity pulsed ultrasound inhibits adipogenic differentiation via HDAC1 signalling in rat visceral preadipocytes

ABSTRACTNon-drug strategy targeting adipocyte differentiation is critical for alleviating visceral obesity and its related diseases. However, whether and how low intensity pulsed ultrasound (LIPUS) could be used for inhibiting visceral adipocyte differentiation is not fully understood. In this study, we aim to investigate the effect and associated mechanism of LIPUS on primary visceral preadipocyte differentiation and explore its potential role for clinical visceral obesity management. The preadipocytes were daily exposed to LIPUS (0.5 MHz, 1.2 MPa) for 10 min. Adipogenic differentiation was estimated by the formation of lipid droplets and the levels of adipogenic transcriptional factors and representative markers. Mitogen-activated protein kinase (MAPK) member proteins and histone acetylation-related molecules were measured by western blotting. LIPUS stimulation with an average acoustic pressure of 1.2 MPa led to a prominent inhibition of adipogenic differentiation and expression of adipogenic markers. As a mechanism, LIPUS treatment increased the nuclear levels of histone deacetylase 1 (HDAC1) and decreased the acetylation of histone 3 and histone 4. Meanwhile, the inhibition of the HDAC1 could block the inhibitory effect of LIPUS on adipogenic differentiation via increasing AcH3 and AcH4 levels. Our study may provide an ultrasound-based promising strategy for clinical visceral obesity control.

63 - Sucrose non-fermenting related kinase regulates cardiomyocyte protection during cardiac stress

Angiotensin II (Ang II), the key effector of the renin-angiotensin system (RAS) promotes the development of Dilated Cardiomyopathy (DCM), which ultimately leads to heart failure (HF). Previously, our lab has reported that a serine threonine kinase, Sucrose nonfermenting 1-related kinase (SNRK), a member of AMP-activated protein kinase (AMPK) family is critical for cardiac metabolism, and specific loss of SNRK in cardiomyocytes results in DCM. Thus, we hypothesize that, SNRK is involved in maintaining cardiac homeostasis and Ang II exacerbates cardiac dysfunction in cardiomyocyte-specific SNRK knockout mice (SNRK-CKO). To investigate this hypothesis, we performed ECHO on 4 months adult SNRK-CKO mice with and without Ang II, and found that most cardiac function parameters were compromised, followed by death in 14 days. These cardiac function defects were not observed in Ang II-infused SNRK-endothelial (EC) KO mice. We next investigated signaling pathways previously implicated in cardiac dysfunction. Indeed, upon stimulation with Ang II, the heart tissue shows downregulation of pERK and pJNK proteins and upregulation of pAKT protein. In contrast, in SNRK-ECKO, pERK and pJNK proteins were upregulated and pAKT protein was downregulated. Because pAKT, is known to increase inflammatory signaling pathways, in particular IKK-NF-κB, we investigated the IKK-NF-κB signaling in heart lysates from SNRK-CKO and SNRK-ECKO mice. Interestingly, we found upregulation of proinflammatory markers such as IL-6, TNFα and p65 NF-κB and downregulation of anti-inflammatory IL-10 in SNRK-CKO hearts only. This increase in inflammatory signaling is often followed by fibrosis, which was observed via Sirus Red staining for collagen accumulation in Ang II-infused SNRK-CKO hearts. At present, we are investigating the inflammatory and signaling pathways associated with lentivirus-mediated knockdown of SNRK in HL-1 cardiomyocytes in vitro. Overall, these results suggest that SNRK could be a potential target in regulating inflammatory mechanisms, which exerts cardioprotective effect in the heart.

Fam198a, a member of secreted kinase, secrets through caveolae biogenesis pathway.

Fam198a is a member of four-jointed protein kinases, a secreted protein kinase family. It was identified as a caveolae-associated protein and colocalized with cavin-1 and caveolin-1 in both tissues and cells. The newly synthesized Fam198a precursor in endoplasmic reticulum (ER) was transported by caveolae biogenesis vesicles to Golgi apparatus in which it was proteolytically cleaved into the secreted mature form. The amino acid mutation analysis identified Arg 120 and 437 as the proteolytic sites in Fam198a precursor during maturation. In mouse embryo fibroblasts (MEFs) obtained from cavin-1-/- or caveolin-1-/- mice, Fam198a precursor was retained in ER and no mature Fam198a could be formed in these cells. Ectopic expression of exogenous cavin-1 in cavin-1-/- MEFs restored the blocked Fam198a post-translational process and secretion. Cavin-1 was also required for Fam198a secretion after its maturation in Golgi apparatus. Ectopic expression of cavin-1 in A549 cells restored the blocked Fam198a secretion. These results suggest that protein secretion is an important function for caveolae biogenesis pathway and the disruption of caveolae system will affect those functions played by the secreted proteins.

SAD-A Promotes Pancreatic ß-Cell Proliferation by Regulating ß-Cell Cycle as a Downstream Target of mTORC1 Signaling

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance and β-cell dysfunction, which leads to the depletion of β-cell mass. Understanding the molecular mechanisms driving islet β-cell dysfunction is paramount for developing therapies to increase β-cell function. The mammalian target of rapamycin complex 1 (mTORC1) plays a key role in regulating β-cell function by integrating growth factors and mitogens to direct cell cycle and survival; yet, mechanistically this process is not fully understood. Synapses of amphids defective protein kinase A (SAD-A) is a member of AMP-activated protein kinase (AMPK)-related family kinases, with high expression in the pancreas. My earlier work demonstrated that SAD-A is a β-cell specific mediator of insulin secretion and islet β-cell size. Furthermore, glucose dramatically stimulated SAD-A protein translation in islets that was potently inhibited by rapamycin, an inhibitor of mTORC1. My recent preliminary studies showed that 1) SAD-A overexpression increases β-cell proliferation in the MIN6 β-cell line and islets; 2) Ablation of SAD-A in pancreas of mice (pSADKO) promotes β-cell apoptosis and attenuates compensatory islet growth in obese mice; 3) SAD-A depletion in the pancreas increases mRNA expression of cyclin D2 in islets of pSADKO mice. Based on these observations, I hypothesize that SAD-A promotes pancreatic β-cell proliferation by regulating β-cell cycle as a downstream target of mTORC1 signaling. Disclosure J. Nie: None. N. Musi: None. Y. Shi: None.