CDK and MAPK Synergistically Regulate Signaling Dynamics via a Shared Multi-site Phosphorylation Region on the Scaffold Protein Ste5.

We report an unanticipated system of joint regulation by cyclin-dependent kinase (CDK) and mitogen-activated protein kinase (MAPK), involving collaborative multi-site phosphorylation of a single substrate. In budding yeast, the protein Ste5 controls signaling through a G1 arrest pathway. Upon cell-cycle entry, CDK inhibits Ste5 via multiple phosphorylation sites, disrupting its membrane association. Using quantitative time-lapse microscopy, we examined Ste5 membrane recruitment dynamics at different cell-cycle stages. Surprisingly, in S phase, where Ste5 recruitment should be blocked, we observed an initial recruitment followed by a steep drop-off. This delayed inhibition revealed a requirement for both CDK activity and negative feedback from the pathway MAPK Fus3. Mutagenesis, mass spectrometry, and electrophoretic analyses suggest that the CDK and MAPK modify shared sites, which are most extensively phosphorylated when both kinases are active and able to bind their docking sites on Ste5. Such collaborative phosphorylation can broaden regulatory inputs and diversify output dynamics of signaling pathways.

STE20-type kinases MST3 and MST4 promote the progression of hepatocellular carcinoma: Evidence from human cell culture and expression profiling of liver biopsies.

Hepatocellular carcinoma (HCC) is one of the most fatal and fastest growing malignancies. Recently, nonalcoholic steatohepatitis (NASH), characterized by liver steatosis, inflammation, cell injury (hepatocyte ballooning), and different stages of fibrosis, has emerged as a major catalyst for HCC. Because the STE20-type kinases, MST3 and MST4, have been described as critical molecular regulators of NASH pathophysiology, we here focused on determining the relevance of these proteins in human HCC. By analyzing public datasets and in-house cohorts, we found that hepatic MST3 and MST4 expression was positively correlated with the incidence and severity of HCC. We also found that the silencing of both MST3 and MST4, but also either of them individually, markedly suppressed the tumorigenesis of human HCC cells including attenuated proliferation, migration, invasion, and epithelial-mesenchymal transition. Mechanistic investigations revealed lower activation of STAT3 signaling in MST3/MST4-deficient hepatocytes and identified GOLGA2 and STRIPAK complex as the binding partners of both MST3 and MST4. These findings reveal that MST3 and MST4 play a critical role in promoting the progression of HCC and suggest that targeting these kinases may provide a novel strategy for the treatment of liver cancer.

MST1/2 exerts a pivotal role in inducing neuroinflammation and Coxsackievirus-A10 replication by interacting with innate immunity.

Coxsackievirus-A10 (CV-A10), responsible for the hand, foot and mouth disease (HFMD) pandemic, could cause serious central nervous system (CNS) complications. The underlying molecular basis of CV-A10 and host interactions inducing neuropathogenesis is still unclear. The Hippo signaling pathway, historically known for a dominator of organ development and homeostasis, has recently been implicated as an immune regulator. However, its role in host defense against CV-A10 has not been investigated. Herein, it was found that CV-A10 proliferated in HMC3 cells and promoted the release of inflammatory cytokines. Moreover, pattern recognition receptors (PRRs)-mediated pathways, including TLR3-TRIF-TRAF3-TBK1-NF-κB axis, RIG-I/MDA5-MAVS-TRAF3-TBK1-NF-κB axis and TLR7-MyD88-IRAK1/IRAK4-TRAF6-TAK1-NF-κB axis, were examined to be elevated under CV-A10 infection. Meanwhile, it was further uncovered that Hippo signaling pathway was inhibited in HMC3 cells with CV-A10 infection. Previous studies have been reported that there exist complex relations between innate immune and Hippo signaling pathway. Then, plasmids of knockdown and overexpression of MST1/2 were transfected into HMC3 cells. Our results showed that MST1/2 suppressed the levels of inflammatory cytokines via interacting with TBK1 and IRAK1, and also enhanced virus production via restricting IRF3 and IFN-ß expressions. Overall, these data obviously pointed out that CV-A10 accelerated the formation of neuroinflammation by the effect of the Hippo pathway on the PRRs-mediated pathway, which delineates a negative immunoregulatory role for MST1/2 in CV-A10 infection and the potential for this pathway to be pharmacologically targeted to treat CV-A10.

LKB1 biology: assessing the therapeutic relevancy of LKB1 inhibitors.

Liver Kinase B1 (LKB1), encoded by Serine-Threonine Kinase 11 (STK11), is a master kinase that regulates cell migration, polarity, proliferation, and metabolism through downstream adenosine monophosphate-activated protein kinase (AMPK) and AMPK-related kinase signalling. Since genetic screens identified STK11 mutations in Peutz-Jeghers Syndrome, STK11 mutants have been implicated in tumourigenesis labelling it as a tumour suppressor. In support of this, several compounds reduce tumour burden through upregulating LKB1 signalling, and LKB1-AMPK agonists are cytotoxic to tumour cells. However, in certain contexts, its role in cancer is paradoxical as LKB1 promotes tumour cell survival by mediating resistance against metabolic and oxidative stressors. LKB1 deficiency has also enhanced the selectivity and cytotoxicity of several cancer therapies. Taken together, there is a need to develop LKB1-specific pharmacological compounds, but prior to developing LKB1 inhibitors, further work is needed to understand LKB1 activity and regulation. However, investigating LKB1 activity is strenuous as cell/tissue type, mutations to the LKB1 signalling pathway, STE-20-related kinase adaptor protein (STRAD) binding, Mouse protein 25-STRAD binding, splicing variants, nucleocytoplasmic shuttling, post-translational modifications, and kinase conformation impact the functional status of LKB1. For these reasons, guidelines to standardize experimental strategies to study LKB1 activity, associate proteins, spliced isoforms, post-translational modifications, and regulation are of upmost importance to the development of LKB1-specific therapies. Therefore, to assess the therapeutic relevancy of LKB1 inhibitors, this review summarizes the importance of LKB1 in cell physiology, highlights contributors to LKB1 activation, and outlines the benefits and risks associated with targeting LKB1.

Mammalian STE20-like kinase 1 inhibits synoviocytes activation in rheumatoid arthritis through mitochondrial dysfunction mediated by SIRT3/mTOR axis.

BACKGROUND: Mammalian STE20-like kinase 1 (MST1) is involved in the occurrence of cancer and autoimmune diseases by regulating cell proliferation, differentiation, apoptosis and other functions. However, its role and downstream targets in rheumatoid arthritis (RA) remain unclear. METHODS: The model of RA fibroblast-like synoviocytes (RA-FLSs) overexpressing MST1 was constructed by lentiviral transfection in vitro and analyzed the effects of MST1 on apoptosis, migration, invasion, and inflammation of RA-FLSs. The effect of MST1 on joint synovial membrane inflammation and bone destruction was observed in vivo by establishing a rat model of arthritis with complete Freund's adjuvant. RESULTS: MST1 is down-regulated in RA-FLSs, and up-regulation of MST1 inhibits the survival, migration, invasion and inflammation of RA-FLSs. Mechanistically, MST1 inhibits SIRT3/mTOR-signaling pathway, inducing decreased mitochondrial autophagy and increased mitochondrial fission, resulting in mitochondrial morphological abnormalities and dysfunction, and ultimately increased apoptosis. We have observed that activation of MST1 alleviates synovial inflammation and bone erosion in vivo. CONCLUSIONS: MST1 reduces the survival, migration, invasion and inflammation of FLSs by inhibiting the SIRT3/mTOR axis to reduce mitochondrial autophagy and promote mitochondrial division, thereby achieving the potential role of relieving rheumatoid arthritis.

Myocardial function using two dimension speckle-tracking echocardiography in children with celiac disease.

The prevalence of cardiac complications linked to celiac disease (CD) is on expanding. This study aimed to evaluate the cardiac function in children with CD using two dimensional speckle tracking echocardiography (2D-STE) to detect early myocardial dysfunction, if any. This cross-sectional study included 40 children with CD as the patient group and 40 healthy age- and sex-matched children served as the control group. High sensitive troponin T (Hs-troponin T), anti-tissue transglutaminase immunoglobulin A (tTG-IgA), hemoglobin, ferritin, albumin, and vitamin D levels were measured in all participants. Conventional, tissue Doppler imaging (TDI), and 2D-STE were performed for all included children. Conventional echocardiographic parameters showed no significant difference between the two groups. Left ventricular global longitudinal strain (LV GLS) obtained by 2D-STE was substantially lower in children with CD than the control group; however, myocardial performance index (MPI) obtained by TDI was significantly higher in children with CD. Hs-troponin T levels were comparable in both groups. LV GLS was positively correlated with hemoglobin, ferritin, and albumin level, but it was inversely correlated with the duration of the disease and anti tTG-IgA.    Conclusion: 2D-STE can detect subclinical early cardiac dysfunction in children with CD and this cardiac injury correlated to the duration and severity of the disease and some nutritional deficiency in these children. What is Known: • The prevalence of cardiac complications linked to celiac disease (CD) is on expanding. • Only one study evaluated cardiac function in children with CD using two dimensional speckle tracking echocardiography (2D-STE). What is New: • Our study found that 2D-STE can detect early subclinical cardiac dysfunction in children with CD. Cardiac injury in theses children correlated to the duration and severity of the disease, hemglobin, ferritin, and albumin levels.

Regulation of sexual differentiation initiation in Schizosaccharomyces pombe.

The fission yeast Schizosaccharomyces pombe is an excellent model organism to explore cellular events owing to rich tools in genetics, molecular biology, cellular biology, and biochemistry. Schizosaccharomyces pombe proliferates continuously when nutrients are abundant but arrests in G1 phase upon depletion of nutrients such as nitrogen and glucose. When cells of opposite mating types are present, cells conjugate, fuse, undergo meiosis, and finally form 4 spores. This sexual differentiation process in S. pombe has been studied extensively. To execute sexual differentiation, the glucose-sensing cAMP-PKA (cyclic adenosine monophosphate-protein kinase A) pathway, nitrogen-sensing TOR (target of rapamycin) pathway, and SAPK (stress-activating protein kinase) pathway are crucial, and the MAPK (mitogen-activating protein kinase) cascade is essential for pheromone sensing. These signals regulate ste11 at the transcriptional and translational levels, and Ste11 is modified in multiple ways. This review summarizes the initiation of sexual differentiation in S. pombe based on results I have helped to obtain, including the work of many excellent researchers.

Clinical study of two-dimensional speckle tracking to evaluate abnormal myocardial motion due to coronary lesions.

OBJECTIVE: To investigate the predictive ability of global longitudinal strain (GLS) and mechanical dispersion for coronary stenosis and provide a more reliable noninvasive method for diagnosis of obstructive coronary artery disease(OCAD). METHODS: Sixty-seven patients diagnosed with suspected CAD were included in the study. Patients with coronary stenosis greater than 50% were assigned as OCAD, while the others were assigned as non obstructive coronary artery disease(NOCAD). General information was collected and patients underwent speckle tracking echocardiogram(STE). RESULTS: Spearman's correlation analysis showed that GLS and mechanical dispersion were positively correlated with the degree of coronary stenosis (r = 0.383, 0.342, p < 0.05), and there was also a positive correlation between GLS and mechanical dispersion (r = 0.327, p < 0.05). GLS, longitudinal strain (LS) of each chamber, and mechanical dispersion were higher in the OCAD group than in the NOCAD group (p < 0.05). Univariate regression analysis showed that GLS, each lumen LS and mechanical dispersion were statistically significant (p < 0.05). Multifactorial regression analysis showed that elevated GLS (p = 0.007) and elevated mechanical dispersion (p = 0.030) were independent risk factors for OCAD. The ROC curves showed that GLS predicted OCAD (AUC area 0.745, 95% CI 0.624 to 0.865) versus mechanical discrete prediction of OCAD (AUC area 0.702, 95% CI 0.569 to 0.834) were more diagnostic than conventional cardiac ultrasound observations of ventricular wall motion abnormalities (AUC area 0.566, 95% CI 0.463 to 0.669). CONCLUSIONS: Combining GLS with mechanical dispersion can rapidly assess OCAD in a very short period, which has strong promotion value and in-depth research value.

Functional studies of McSTE24, McCYP305a1, and McJHEH, three essential genes act in cantharidin biosynthesis in the blister beetle (Coleoptera: Meloidae).

Cantharidin is a toxic defensive substance secreted by most blister beetles when attacked. It has been used to treat many complex diseases since ancient times and has recently regained popularity as an anticancer agent. However, the detailed mechanism of the cantharidin biosynthesis has not been completely addressed. In this study, we cloned McSTE24 (encoding STE24 endopeptidase) from terpenoid backbone pathway, McCYP305a1 (encoding cytochrome P450, family 305) and McJHEH [encoding subfamily A, polypeptide 1 and juvenile hormone (JH) epoxide hydrolase] associated to JH synthesis/degradation in the blister beetle Mylabris cichorii (Linnaeus, 1758, Coleoptera: Meloidae). Expression pattern analyses across developmental stages in adult males revealed that the expressions of 3 transcripts were closely linked to cantharidin titer exclusively during the peak period of cantharidin synthesis (20-25 days old). In contrast, at other stages, these genes may primarily regulate different biological processes. When RNA interference with double-stranded RNA suppressed the expressions of the 3 genes individually, significant reductions in cantharidin production were observed in males and also in females following McJHEH knockdown, indicating that these 3 genes might primarily contribute to cantharidin biosynthesis in males, but not in females, while females could self-synthesis a small amount of cantharidin. These findings support the previously hypothesized sexual dimorphism in cantharidin biosynthesis during the adult phase. McCYP305a1 collaborates with its upstream gene McSTE24 in cantharidin biosynthesis, while McJHEH independently regulates cantharidin biosynthesis in males.

STE20 phosphorylation of AMPK-related kinases revealed by biochemical purifications combined with genetics.

We have recently purified mammalian sterile 20 (STE20)-like kinase 3 (MST3) as a kinase for the multifunctional kinases, AMP-activated protein kinase-related kinases (ARKs). However, unresolved questions from this study, such as remaining phosphorylation activities following deletion of the Mst3 gene from human embryonic kidney cells and mice, led us to conclude that there were additional kinases for ARKs. Further purification recovered Ca2+/calmodulin-dependent protein kinase kinases 1 and 2 (CaMKK1 and 2), and a third round of purification revealed mitogen-activated protein kinase kinase kinase kinase 5 (MAP4K5) as potential kinases of ARKs. We then demonstrated that MST3 and MAP4K5, both belonging to the STE20-like kinase family, could phosphorylate all 14 ARKs both in vivo and in vitro. Further examination of all 28 STE20 kinases detected variable phosphorylation activity on AMP-activated protein kinase (AMPK) and the salt-inducible kinase 3 (SIK3). Taken together, our results have revealed novel relationships between STE20 kinases and ARKs, with potential physiological and pathological implications.

Scaffold proteins as dynamic integrators of biological processes.

Scaffold proteins act as molecular hubs for the docking of multiple proteins to organize efficient functional units for signaling cascades. Over 300 human proteins have been characterized as scaffolds, acting in a variety of signaling pathways. While the term scaffold implies a static, supportive platform, it is now clear that scaffolds are not simply inert docking stations but can undergo conformational changes that affect their dependent signaling pathways. In this review, we catalog scaffold proteins that have been shown to undergo actionable conformational changes, with a focus on the role that conformational change plays in the activity of the classic yeast scaffold STE5, as well as three human scaffold proteins (KSR, NEMO, SHANK3) that are integral to well-known signaling pathways (RAS, NF-κB, postsynaptic density). We also discuss scaffold protein conformational changes vis-à-vis liquid-liquid phase separation. Changes in scaffold structure have also been implicated in human disease, and we discuss how aberrant conformational changes may be involved in disease-related dysregulation of scaffold and signaling functions. Finally, we discuss how understanding these conformational dynamics will provide insight into the flexibility of signaling cascades and may enhance our ability to treat scaffold-associated diseases.

Thirty years of the NaCl cotransporter: from cloning to physiology and structure.

The primary structure of the thiazide-sensitive NaCl cotransporter (NCC) was resolved 30 years ago by the molecular identification of the cDNA encoding this cotransporter, from the winter's flounder urinary bladder, following a functional expression strategy. This review outlines some aspects of how the knowledge about thiazide diuretics and NCC evolved, the history of the cloning process, and the expansion of the SLC12 family of electroneutral cotransporters. The diseases associated with activation or inactivation of NCC are discussed, as well as the molecular model by which the activity of NCC is regulated. The controversies in the field are discussed as well as recent publication of the three-dimensional model of NCC obtained by cryo-electron microscopy, revealing not only the amino acid residues critical for Na+ and Cl- translocation but also the residues critical for polythiazide binding to the transporter, opening the possibility for a new era in thiazide diuretic therapy.

The Ste20-like kinase - a Jack of all trades?

Over the past 20 years, the Ste20-like kinase (SLK; also known as STK2) has emerged as a central regulator of cytoskeletal dynamics. Reorganization of the cytoskeleton is necessary for a plethora of biological processes including apoptosis, proliferation, migration, tissue repair and signaling. Several studies have also uncovered a role for SLK in disease progression and cancer. Here, we review the recent findings in the SLK field and summarize the various roles of SLK in different animal models and discuss the biochemical mechanisms regulating SLK activity. Together, these studies have revealed multiple roles for SLK in coupling cytoskeletal dynamics to cell growth, in muscle repair and in negative-feedback loops critical for cancer progression. Furthermore, the ability of SLK to regulate some systems appears to be kinase activity independent, suggesting that it may be an important scaffold for signal transduction pathways. These various findings reveal highly complex functions and regulation patterns of SLK in development and disease, making it a potential therapeutic target.

Protective effects of melatonin on myocardial microvascular endothelial cell injury under hypertensive state by regulating Mst1.

BACKGROUND: This study explored the protective effects of melatonin on the hypertensive model in myocardial microvascular endothelial cells. METHODS: Mouse myocardial microvascular endothelial cells were intervened with angiotensin II to establish hypertensive cell model and divided into control, hypertension (HP), hypertension + adenovirus negative control (HP + Ad-NC), hypertension + adenovirus carrying Mst1 (HP + Ad-Mst1), hypertension + melatonin (HP + MT), hypertension + adenovirus negative control + melatonin (HP + Ad-NC + MT), and hypertension + adenovirus carrying Mst1 + melatonin (HP + Ad-Mst1 + MT) groups. Autophagosomes were observed by transmission electron microscope. Mitochondrial membrane potential was detected by JC-1 staining. Apoptosis was detected by flow cytometry. Oxidative stress markers of MDA, SOD and GSH-PX were measured. The expression of LC3 and p62 was detected by immunofluorescence. Expression levels of Mst1, p-Mst1, Beclin1, LC3, and P62 were detected with Western blot. RESULTS: Compared with the control group, the autophagosomes in HP, HP + Ad-Mst1, and HP + Ad-NC groups were significantly reduced. Compared with HP group, the autophagosomes in HP + Ad-Mst1 group were significantly reduced. The apoptosis of HP + MT group was significantly lower than HP group. Compared with HP + Ad-Mst1 group, the apoptosis of HP + Ad-Mst1 + MT group was significantly reduced. The ratio of JC-1 monomer in HP + MT group was significantly lower than HP group. Compared with HP + Ad-Mst1 group, the mitochondrial membrane potential of HP + Ad-Mst1 + MT group was also significantly reduced. MDA content in HP + MT group was significantly reduced, but SOD and GSH-PX activities were significantly increased. Compared with HP + Ad-Mst1 group, MDA content in HP + Ad-Mst1 + MT group was significantly reduced, whereas SOD and GSH-PX activities were increased significantly. Mst1 and p-Mst1 proteins in HP + MT group were significantly reduced. Compared with HP + Ad-Mst1 group, Mst1 and p-Mst1 in HP + Ad-Mst1 + MT group were reduced. P62 level was significantly decreased, while Beclin1 and LC3II levels were significantly increased. P62 in HP + MT group was significantly reduced, while Beclin1 and LC3II were significantly increased. Compared with HP + Ad-Mst1 group, P62 in HP + Ad-Mst1 + MT group was significantly reduced, but Beclin1 and LC3II were significantly increased. CONCLUSION: Melatonin may inhibit apoptosis, increase mitochondrial membrane potential, and increase autophagy of myocardial microvascular endothelial cells under hypertensive state via inhibiting Mst1 expression, thereby exerting myocardial protective effect.

Evaluation of right atrial function by two-dimensional echocardiography and strain imaging in patients with RCA CTO recanalization.

OBJECTIVES: The right heart is mainly supplied with blood by the right coronary artery (RCA). The impact of RCA chronic total occlusion (CTO) on the function of the right heart [right atrium (RA) and ventricle (RV)] and whether successful recanalization of a RCA CTO improves the function of the right heart is not clearly understood yet. We aimed to evaluate right atrial function after recanalization of the RCA using transthoracic echocardiography with additional strain imaging. METHODS AND RESULTS: Fifty-five patients undergoing RCA CTO recanalization at the University Medical Center of Mainz were included in the study. Right atrial strain was assessed before and 6 months after successful CTO revascularization. The median age of the total collective was 66 (50-90) years. We did not find difference in our analysis of RA Volume (p 0.086), RA area (p 0.093), RA major dimension (p 0.32) and RA minor dimension (p 0.139) at baseline and follow-up. Mean RA reservoir strain at baseline was 30.9% (21.1-43.0) vs. 33.4% (20.7-47.7) at follow up (p < 0.001). Mean RA conduit strain was - 17.5% (- 10.7-(- 29.7)) at baseline vs. - 18.2% (- 9.6-(- 31.7)) at follow-up (p = 0.346). Mean RA contraction strain was - 12.9% (- 8.0- (- 21.3)) at baseline vs. - 15.5% (- 8.7-(- 26.6)) at follow-up (p < 0.001). CONCLUSION: Right atrial function was altered in patients with RCA CTO. Successful revascularisation of an RCA CTO improved RA function assessed by strain imaging at follow-up.

Acute hyperglycemia, a rabble-rouser or innocent bystander? A prospective analysis of clinical implications of acute hyperglycemia in STE-ACS patients.

BACKGROUND: Acute hyperglycemia is considered an independent prognosticator of both in-hospital and long-term outcomes in patients with acute coronary syndrome (ACS). This study aimed To analyze the incidence of acute hyperglycemia and its impact on the adverse in-hospital outcome in patients with STE-ACS undergoing primary percutaneous coronary intervention (PCI). METHODS: In this study, we enrolled patients presenting with STE-ACS and undergoing primary PCI at a tertiary care cardiac center. Acute hyperglycemia was defined as random plasma glucose (RBS) > 200 mg/dl at the time of presentation to the emergency room. RESULTS: Of the 4470 patients, 78.8% were males, and the mean age was 55.52 ± 11 years. In total, 39.4% (1759) were found to have acute hyperglycemia, and of these, 59% (1037) were already diagnosed with diabetes. Patients with acute hyperglycemia were observed to have a higher incidence of heart failure (8.2% vs. 5.5%; p < 0.001), contrast-induced nephropathy (10.9% vs. 7.4%; p < 0.001), and in-hospital mortality (5.7% vs. 2.5%; p < 0.001). On multivariable analysis, acute hyperglycemia was found to be an independent predictor of mortality with an adjusted odds ratio of 1.81 [1.28-2.55]. Multi-vessel disease (1.73 [1.17-2.56]), pre-procedure left ventricular end-diastolic pressure (LVEDP) (1.02 [1.0-1.03]), and Killip class III/IV (4.55 [3.09-6.71]) were found to be the additional independent predictors of in-hospital mortality. CONCLUSIONS: Acute hyperglycemia, regardless of diabetic status, is an independent predictor of in-hospital mortality among patients with STE-ACS undergoing primary PCI. Acute hyperglycemia, along with other significant predictors such as multi-vessel involvement, LVEDP, and Killip class III/IV, can be considered for the risk stratification of these patients.

Rho family GTPase signaling through type II p21-activated kinases.

Signaling from the Rho family small GTPases controls a wide range of signaling outcomes. Key among the downstream effectors for many of the Rho GTPases are the p21-activated kinases, or PAK group. The PAK family comprises two types, the type I PAKs (PAK1, 2 and 3) and the type II PAKs (PAK4, 5 and 6), which have distinct structures and mechanisms of regulation. In this review, we discuss signal transduction from Rho GTPases with a focus on the type II PAKs. We discuss the role of PAKs in signal transduction pathways and selectivity of Rho GTPases for PAK family members. We consider the less well studied of the Rho GTPases and their PAK-related signaling. We then discuss the molecular basis for kinase domain recognition of substrates and for regulation of signaling. We conclude with a discussion of the role of PAKs in cross talk between Rho family small GTPases and the roles of PAKs in disease.

Coronary microvascular dysfunction affects left ventricular global longitudinal strain response to dipyridamole stress echocardiography: a pilot study.

The aim is to investigate, by means of speckle tracking echocardiography, left ventricular (LV) contractile function at rest and during dipyridamole stress in patients with coronary microvascular dysfunction (CMD). 59 patients (39% women, mean age 65.6 ± 6.1 years) with history of chest pain and without obstructive coronary artery disease (CAD) underwent dipyridamole stress echocardiography. Coronary flow was assessed in the left anterior descending coronary artery. Coronary flow reserve (CFR) was determined as the ratio of hyperaemic to baseline diastolic coronary flow velocity. CMD was defined as CFR < 2. Global longitudinal strain (GLS) was measured at rest and at peak dose. Nineteen patients (32%) among the overall population showed CMD. Baseline GLS was significantly lower in patients with CMD (- 16.8 ± 2.7 vs. - 19.1 ± 3.1, p < 0.01). A different contractile response to dipyridamole infusion was observed between the two groups: GLS significantly increased up to peak dose in patients without CMD (from - 19.1 ± 3.1 to - 20.2 ± 3.1, p < 0.01), and significantly decreased in patients with CMD (from - 16.8 ± 2.7 to - 15.8 ± 2.7, p < 0.01). There was a significant inverse correlation between CFR and ∆GLS (r = - 0.82, p < 0.01). Rest GLS and GLS response to dipyridamole stress are markedly impaired among patients with chest pain syndrome, non-obstructive CAD and CMD, reflecting subclinical LV systolic dysfunction and lack of LV contractile reserve due to underlying myocardial ischemia.

Three, dynamic variants of ST segment elevations in a patient with osteosarcoma and cardiac metastasis.

In the right clinical setting, ST segment elevation (STE) on electrocardiogram (ECG) is most concerning for acute injury due to transmural myocardial ischemia. This frequently points to significant epicardial coronary artery disease, mandating emergent cardiac intervention. In rare cases, cardiac metastases may cause transient STE. We present a case of a 28-year-old male patient with metastatic osteosarcoma with STE in three different ECG territories over ten months. Several transient, dynamic patterns of STE were noted: anteroseptal leads concerning for acute injury with reciprocal ST depressions in inferior leads, lateral leads, inferior leads with reciprocal ST depression in lateral leads, followed by STE again in lateral leads. Given the patient's young age, absence of cardiac history or symptoms, personal preference, bleeding risk, and cancer prognosis, cardiac catheterization was never pursued. We present this case to remind providers to include metastatic cancer in the differential diagnosis of STE on ECG, and that these changes can be dynamic.

A Protein-Protein Interaction Analysis Suggests a Wide Range of New Functions for the p21-Activated Kinase (PAK) Ste20.

The p21-activated kinases (PAKs) are important signaling proteins. They contribute to a surprisingly wide range of cellular processes and play critical roles in a number of human diseases including cancer, neurological disorders and cardiac diseases. To get a better understanding of PAK functions, mechanisms and integration of various cellular activities, we screened for proteins that bind to the budding yeast PAK Ste20 as an example, using the split-ubiquitin technique. We identified 56 proteins, most of them not described previously as Ste20 interactors. The proteins fall into a small number of functional categories such as vesicle transport and translation. We analyzed the roles of Ste20 in glucose metabolism and gene expression further. Ste20 has a well-established role in the adaptation to changing environmental conditions through the stimulation of mitogen-activated protein kinase (MAPK) pathways which eventually leads to transcription factor activation. This includes filamentous growth, an adaptation to nutrient depletion. Here we show that Ste20 also induces filamentous growth through interaction with nuclear proteins such as Sac3, Ctk1 and Hmt1, key regulators of gene expression. Combining our observations and the data published by others, we suggest that Ste20 has several new and unexpected functions.