α2C-Adrenoceptor polymorphism is associated with improved event-free survival in patients with dilated cardiomyopathy

Aims The sympathetic nervous system plays a central role in cardiac growth but its overstimulation is associated with increased mortality in patients with chronic heart failure. Pre-synaptic α2-adrenoceptors are essential feedback regulators to control the release of norepinephrine from sympathetic nerves. In this study we tested whether a deletion polymorphism in the human α2C-adrenoceptor gene (α2CDel322-325) affects progression of heart failure in patients with dilated cardiomyopathy (DCM). Methods and results We genotyped and phenotyped 345 patients presenting with DCM in the heart transplant unit of the German Heart Institute, starting in 1994. Patients were treated according to guidelines (99% ACEI, 76% β-blockers) and were followed until December 2002 or until a first event [death, heart transplantation, or implantation of a left ventricular assist device (LVAD) for a life-threatening condition] occurred. Mean follow-up time was 249 weeks (4.9 years) in event-free patients and 104 weeks (2 years) in patients with events. During follow-up, 51% of the patients exhibited an event: death (18%), implantation of LVAD as bridging for transplantation (7%), or heart transplantation (25%). By Kaplan-Meier analysis, DCM patients with the deletion variant Del322-325 in the α2C-adrenoceptor showed significantly decreased event rates (P=0.0043). Cox regression analysis revealed that the presence of the deletion was associated with reduced death rate (relative risk: 0.129, 95% CI: 0.18-0.9441, P=0.044) and event rates (relative risk: 0.167, 95% CI: 0.041-0.685, P=0.012). Conclusion α2C-Adrenoceptor deletion may be a novel, strong, and independent predictor of reduced event rates in DCM patients treated according to guideline

Glycolytic flux control by drugging phosphoglycolate phosphatase

Targeting the intrinsic metabolism of immune or tumor cells is a therapeutic strategy in autoimmunity, chronic inflammation or cancer. Metabolite repair enzymes may represent an alternative target class for selective metabolic inhibition, but pharmacological tools to test this concept are needed. Here, we demonstrate that phosphoglycolate phosphatase (PGP), a prototypical metabolite repair enzyme in glycolysis, is a pharmacologically actionable target. Using a combination of small molecule screening, protein crystallography, molecular dynamics simulations and NMR metabolomics, we discover and analyze a compound (CP1) that inhibits PGP with high selectivity and submicromolar potency. CP1 locks the phosphatase in a catalytically inactive conformation, dampens glycolytic flux, and phenocopies effects of cellular PGP-deficiency. This study provides key insights into effective and precise PGP targeting, at the same time validating an allosteric approach to control glycolysis that could advance discoveries of innovative therapeutic candidates

An essential developmental function for murine phosphoglycolate phosphatase in safeguarding cell proliferation

Mammalian phosphoglycolate phosphatase (PGP) is thought to target phosphoglycolate, a 2-deoxyribose fragment derived from the repair of oxidative DNA lesions. However, the physiological role of this activity and the biological function of the DNA damage product phosphoglycolate is unknown. We now show that knockin replacement of murine Pgp with its phosphatase-inactive Pgp$^{D34N}$ mutant is embryonically lethal due to intrauterine growth arrest and developmental delay in midgestation. PGP inactivation attenuated triosephosphate isomerase activity, increased triglyceride levels at the expense of the cellular phosphatidylcholine content, and inhibited cell proliferation. These effects were prevented under hypoxic conditions or by blocking phosphoglycolate release from damaged DNA. Thus, PGP is essential to sustain cell proliferation in the presence of oxygen. Collectively, our findings reveal a previously unknown mechanism coupling a DNA damage repair product to the control of intermediary metabolism and cell proliferation

7,8-Dihydroxyflavone is a direct inhibitor of pyridoxal phosphatase

Vitamin B6 deficiency has been linked to cognitive impairment in human brain disorders for decades. Still, the molecular mechanisms linking vitamin B6 to these pathologies remain poorly understood, and whether vitamin B6 supplementation improves cognition is unclear as well. Pyridoxal phosphatase (PDXP), an enzyme that controls levels of pyridoxal 5’-phosphate (PLP), the co-enzymatically active form of vitamin B6, may represent an alternative therapeutic entry point into vitamin B6-associated pathologies. However, pharmacological PDXP inhibitors to test this concept are lacking. We now identify a PDXP and age-dependent decline of PLP levels in the murine hippocampus that provides a rationale for the development of PDXP inhibitors. Using a combination of small molecule screening, protein crystallography and biolayer interferometry, we discover and analyze 7,8-dihydroxyflavone (7,8-DHF) as a direct and potent PDXP inhibitor. 7,8-DHF binds and reversibly inhibits PDXP with low micromolar affinity and sub-micromolar potency. In mouse hippocampal neurons, 7,8-DHF increases PLP in a PDXP-dependent manner. These findings validate PDXP as a druggable target. Of note, 7,8-DHF is a well-studied molecule in brain disorder models, although its mechanism of action is actively debated. Our discovery of 7,8-DHF as a PDXP inhibitor offers novel mechanistic insights into the controversy surrounding 7,8-DHF-mediated effects in the brain