ATP-activated P2X2 current in mouse spermatozoa

Sperm cells acquire hyperactivated motility as they ascend the female reproductive tract, which enables them to overcome barriers and penetrate the cumulus and zona pellucida surrounding the egg. This enhanced motility requires Ca(2+) entry via cation channel of sperm (CatSper) Ca(2+)-selective ion channels in the sperm tail. Ca(2+) entry via CatSper is enhanced by the membrane hyperpolarization mediated by Slo3, a K(+) channel also present in the sperm tail. To date, no transmitter-mediated currents have been reported in sperm and no currents have been detected in the head or midpiece of mature spermatozoa. We screened a number of neurotransmitters and biomolecules to examine their ability to induce ion channel currents in the whole spermatozoa. Surprisingly, we find that none of the previously reported neurotransmitter receptors detected by antibodies alone are functional in mouse spermatozoa. Instead, we find that mouse spermatozoa have a cation-nonselective current in the midpiece of spermatozoa that is activated by external ATP, consistent with an ATP-mediated increase in intracellular Ca(2+) as previously reported. The ATP-dependent current is not detected in mice lacking the P2X2 receptor gene (P2rx2(-/-)). Furthermore, the slowly desensitizing and strongly outwardly rectifying ATP-gated current has the biophysical and pharmacological properties that mimic heterologously expressed mouse P2X2. We conclude that the ATP-induced current on mouse spermatozoa is mediated by the P2X2 purinergic receptor/channel. Despite the loss of ATP-gated current, P2rx2(-/-) spermatozoa have normal progressive motility, hyperactivated motility, and acrosome reactions. However, fertility of P2rx2(-/-) males declines with frequent mating over days, suggesting that P2X2 receptor adds a selection advantage under these conditions.     

IGF2BP2 and IGF2 genetic effects in diabetes and diabetic nephropathy

ObjectiveThe IGF2BP2 gene is located on chromosome 3q27.2 within a region linked to type 1 diabetes (T1D), type 2 diabetes (T2D) and diabetic nephropathy (DN). Its protein functionally binds to 5’-UTR of the imprinting IGF2 gene. The present study aims to evaluate the IGF2BP2-IGF2 genetic effects in diabetes and DN.Materials and MethodsThree cohorts including T1D with and without DN (n = 1139) of European descents from the GoKinD study, Swedish T1D with and without DN (n = 303) and Czech control subjects without diabetes, T1D, T2D with and without DN (n = 1418) were enrolled in TaqMan genotyping experiments for IGF2BP2 rs4402960 and IGF2 rs10770125. Igf2bp2 gene expression in kidney tissues of db/db and control mice at the ages of 5 and 26 weeks was examined with real time RT-PCR and Western blot.ResultsAn association of IGF2BP2 rs4402960 with T2D in the Czech population was replicated. This IGF2BP2 polymorphism (P = 0.037, OR = 0.69 95% CI 0.49–0.98) was found to be associated with DN in male not in female patients with T1D selected from the GoKinD study. In the analyses of combined the GoKinD, Czech and Swedish populations, the association between IGF2BP2 polymorphism and DN in male patients with T1D was still significant (P = 0.030, OR = 0.73, 95% CI 0.54–0.97). IGF2 rs10770125 was also associated with DN in male T1D patients of the GoKinD population (P = 0.038, OR = 0.67 95% CI 0.46–0.98). There might be a genetic interaction between IGF2BP2 and IGF2 (P = 0.05). The Igf2bp2 gene expression levels were increased in the kidneys of db/db mice compared to controls at the age of 5 weeks but not at 26 weeks.ConclusionsThe present study has replicated the association of IGF2BP2 rs4402960 with T2D in the Czech population and provided data suggesting that IGF2BP2 may have genetic interaction with IGF2 with a protective effect against DN in male patients with T1D.     

Identification of CYP2C9*2 allele in HepG2 cell line

Background Hepatoma is caused by many factors including alcohol, chemicals, viral infection, and chronic inflammation. Cytochrome P450 polymorphism plays an important role in its pathogenesis. CYP2D6, CYP2E1, and CYP1A1 have been identified to be related with hepatic carcinogenesis and tumor size and stage. However, no studies have been performed on CYP2C9, a major CYP in the liver and hepatoma. Aim of the study To identify if there is polymorphism of CYP2C9 in a HepG2 cell line. Methods A pair of primers was used to clone CYP2C9 exon 3 region and subsequently sequenced. The sequence was compared to normal CYP2C9 for identification of any mutation. Results A point mutation was identified. It was located in the amino acid number 144 of CYP2C9 protein with the change of normal amino acid arginine into cysteine, which is the same as identified in poor metabolism patients as homozygous CYP2C9*2. Conclusions There is a mutation (CYP2C9*2/ CYP2C9*2) in a HepG2 cell line. Thus, polymorphism of CYP2C9 may also be involved in the carcinogenesis of hepatoma as CYPs2D6 and 2E1.     

Albuminuria improves R2CHA2DS2-VASc score in predicting mortality in high cardiovascular risk population

Background and aimsThe CHA₂DS₂-VASc score estimates the risk of cardioembolism in patients with atrial fibrillation (AF). It also predicts vascular events and death in different clinical settings, even in the absence of AF. The R₂CHA₂DS₂-VASc score, obtained by adding the glomerular filtration rate to CHA₂DS₂-VASc, shows a higher prediction ability for new events and all-cause mortality.The present study aims to assess whether the addition of albuminuria to R₂CHA₂DS₂-VASc score further improves its discrimination ability in predicting all-cause mortality in a sample of high cardiovascular risk population.Methods and ResultsProspective, monocentric, observational study, evaluating a subset of 737 subjects consecutively undergoing to coronary angiography at Coronary Unit of Scientific Institute “Casa Sollievo della Sofferenza” from June 2016 to December 2018.The presence of albuminuria was significantly associated with all-cause mortality (p < 0.0001). Any one-point increase of Alb-R₂CHA₂DS₂-VASc score increased mortality of about 1.5-fold (adjusted HR 1.49; 95%CI: 1.37–1.63; p < 0.0001). Considering tertiles of Alb-R₂CHA₂DS₂-VASc, the third tertile showed a 9.5-fold increased risk of mortality (HR 9.52; 95% CI: 5.15–17.60, p < 0.001).Comparing the two scores, the Alb-R₂CHA₂DS₂-VASc score (C-statistic = 0.751; 95%CI: 0.69–0.81) outperformed the R₂-CHA₂DS₂-VASc score (C-statistic = 0.736; 95%CI: 0.68–0.961) in predicting mortality (delta C-statistic = 0.015; 95%CI: 0.001–0.029). The better prediction ability of the Alb-R₂CHA₂DS₂-VASc score was also proven by an IDI of 0.024 (p < 0.0001) and a relative IDI of 24.11% (p < 0.0001), with an NRI = 0.608 (p < 0.00001).ConclusionsThe addition of albuminuria to R₂CHA₂DS₂-VASc significantly and independently predicts the risk of all-cause mortality in a sample of high CV risk patients. Moreover, Alb-R₂CHA₂DS₂-VASc outperforms R₂CHA₂DS₂-VASc.     

自发性高血压大鼠肾上腺髓质素2水平的变化

背景肾上腺髓质素2(ADM2)是2004年2月由日本学者所报道的,被认为是降钙素/降钙素基因相关肽超家族的一个新肽。这与2003年11月美国斯坦福大学Dr.Roh等人发现的垂体中叶素在核苷酸和氨基酸序列上完全一致,二者被认为是同物异名。该家族的已有成员包括肾上腺髓质素、降钙素基因相关肽、降钙素和胰岛淀粉样多肽。目前研究结果表明,肾上腺髓质素2参与了心血管的调节。目的研究自发性高血压大鼠(SHR)血浆ADM2[即:垂体中叶素(IMD)]的含量和在组织中水平的升降、基因表达的变化、血浆ADM2含量与血压和心质量/体质量(HM/BM)的相互关系。方法11周龄的雄性SHR8只为实验组,同龄的雄性WistarKyoto(WKY)大鼠8只为对照组。放射免疫分析方法测定血浆和组织中ADM2的含量;RT-PCR方法测定组织中ADM2的mRNA表达;心室导管方法测定血压和心功能的变化。结果1)与WKY大鼠相比,SHR的血浆、心肌和主动脉中ADM2的含量显著增高,分别为50.0%[(317.2±25.2)vs(211.4±15.0)ng/L,P<0.01]、46.5%[(293.6±34.7)vs(200.4±21.6)ng/g,P<0.05]和32.1%[(1009.0±50.1)vs(763.8±35.0)ng/g,P<0.01];2)SHR心肌和主动脉中ADM2的mRNA水平高于WKY大鼠,分别升高76.11%[(0.75±0.33)vs(0.46±0.26)%,P<0.05]和171.1%[(1.43±0.36)%vs(0.66±0.35)%,P<0.01];3)实验组的ADM2血浆含量和收缩压呈显著负相关(r=-0.822,P<0.05)。结论ADM2作为一种心血管的活性肽,在血压调节和心肌保护过程中具有重要的意义。     

自发性高血压大鼠肾上腺髓质素2水平的变化

背景 肾上腺髓质素2(ADM2)是2004年2月由日本学者所报道的,被认为是降钙素/降钙素基因相关肽超家族的一个新肽.这与2003年11月美国斯坦福大学Dr.Roh等人发现的垂体中叶素在核苷酸和氨基酸序列上完全一致,二者被认为是同物异名.该家族的已有成员包括肾上腺髓质素、降钙素基因相关肽、降钙素和胰岛淀粉样多肽.目前研究结果表明,肾上腺髓质素2参与了心血管的调节.目的 研究自发性高血压大鼠(SHR)血浆ADM2[即:垂体中叶素(IMD)]的含量和在组织中水平的升降、基因表达的变化、血浆ADM2含量与血压和心质量/体质量(HM/BM)的相互关系.方法 11周龄的雄性SHR 8只为实验组,同龄的雄性Wistar Kyoto(WKY)大鼠8只为对照组.放射免疫分析方法测定血浆和组织中ADM2的含量;RT-PCR方法测定组织中ADM2的mRNA表达;心室导管方法测定血压和心功能的变化.结果 1)与WKY大鼠相比,SHR的血浆、心肌和主动脉中ADM2的含量显著增高,分别为50.0%[(317.2±25.2)vs(211.4±15.0)ng/L,P＜0.01]、46.5%[(293.6±34.7)vs(200.4±21.6)ng/g,P＜0.05]和32.1%[(1009.0±50.1) vs(763.8±35.0)ng/g,P＜0.01];2)SHR心肌和主动脉中ADM2的mRNA水平高于WKY大鼠,分别升高76.11%[(0.75±0.33)vs(0.46±0.26)%,P＜0.05]和171.1%[(1.43±0.36)%vs(0.66±0.35)%,P＜0.01];3)实验组的ADM2血浆含量和收缩压呈显著负相关(r=-0.822,P＜0.05).结论 ADM2作为一种心血管的活性肽,在血压调节和心肌保护过程中具有重要的意义.     

Mutations in MINAR2 encoding membrane integral NOTCH2-associated receptor 2 cause deafness in humans and mice

Discovery of deafness genes and elucidating their functions have substantially contributed to our understanding of hearing physiology and its pathologies. Here we report on DNA variants in MINAR2, encoding membrane integral NOTCH2-associated receptor 2, in four families underlying autosomal recessive nonsyndromic deafness. Neurologic evaluation of affected individuals at ages ranging from 4 to 80 y old does not show additional abnormalities. MINAR2 is a recently annotated gene with limited functional understanding. We detected three MINAR2 variants, c.144G > A (p.Trp48*), c.412_419delCGGTTTTG (p.Arg138Valfs*10), and c.393G > T, in 13 individuals with congenital- or prelingual-onset severe-to-profound sensorineural hearing loss (HL). The c.393G > T variant is shown to disrupt a splice donor site. We show that Minar2 is expressed in the mouse inner ear, with the protein localizing mainly in the hair cells, spiral ganglia, the spiral limbus, and the stria vascularis. Mice with loss of function of the Minar2 protein (Minar2^tm1b/tm1b) present with rapidly progressive sensorineural HL associated with a reduction in outer hair cell stereocilia in the shortest row and degeneration of hair cells at a later age. We conclude that MINAR2 is essential for hearing in humans and mice and its disruption leads to sensorineural HL. Progressive HL observed in mice and in some affected individuals and as well as relative preservation of hair cells provides an opportunity to interfere with HL using genetic therapies.

Hearing loss (HL) is one of the most common sensory deficits, affecting ∼1 in 500 newborns (1). Genetic factors are implicated in the majority of cases, with more than 80% of the inherited form exhibiting autosomal recessive transmission (2). No additional findings are present in over 70% of the cases, which are then classified as nonsyndromic HL (Hereditary Hearing Loss Homepage, https://hereditaryhearingloss.org/) (2, 3). Genetic testing for etiologic evaluation has become a standard of care in people with congenital or childhood-onset sensorineural HL, which is caused by pathologies of the inner ear and auditory nerve (4, 5). Recent studies have shown that screening all recognized HL genes for variants reveals underlying cause in about half of the affected individuals, leaving a significant portion of people with HL with an unknown etiology (6–9). In the era of emerging genetic therapies for HL, finding the etiology of HL in affected individuals has become a critical task. This is especially relevant for progressive HL, as genetic therapies may potentially stop progression while cochlear hair cells are still alive (10–12).MINAR2 (previously known as uncharacterized protein KIAA1024L and mouse gene A730017C20Rik) has recently been identified, and based on its structural similarity to MINAR1, named as major intrinsically disordered NOTCH2-associated receptor 2 or membrane integral NOTCH2-associated receptor 2 (13). A mutant mouse model of Minar2 showed motor deficits similar to those seen in Parkinson disease, with no information about hearing abnormalities (13). A Minar2 mutant mouse line, Minar2^tm1b, has also recently been reported to show no auditory brainstem responses at 14 wk old as part of a large HL screen (Mouse Genome Informatics [MGI]: 2442934) (11). Functional aspects of MINAR2 and consequences of its dysfunction in humans remain unknown.In this study, to better map the landscape of hereditary HL, we sought DNA variants underlying deafness in 13 affected individuals from four families. We identified three different MINAR2 variants in the families cosegregating with HL. We further showed that homozygous Minar2^tm1b mutant mice develop rapidly progressive HL associated with changes in outer hair cell stereocilia. Finally, via in vitro studies we demonstrated that MINAR2 suppresses NOTCH2, suggesting that notch signaling might play a role in pathogenesis.     

P2Y2 receptor-mediated Ca2+ signaling and spontaneous Ca2+ releases in human valvular myofibroblasts

Valvular myofibroblasts (VMFs), being the most predominant cells in the cardiac valve, perform a variety of functions to maintain normal valvular physiology. These functions, such as contraction, proliferation, and wound repair, are all directly or indirectly mediated by intracellular Ca(2+) concentrations ([Ca (2+)](i)). Knowing how [Ca(2+)](i) is regulated by vasoactive agents in VMFs enriches the understanding of valvular biology in both health and diseases. In this study we examined the characteristics of purinergic agonist-induced [Ca(2+)] (i) responses and observed spontaneous Ca(2+) releases in cultured human VMFs. Secondary cultures of human mitral VMFs were incubated with the Ca(2+)-sensitive fluorescent indicator fura-2 or fluo-4 and visualized with fluorescence microscopy. Both ATP and UTP activated P(2Y2) receptors and induced endoplasmic reticulum (ER) Ca(2+) release and Ca(2+) influx. The lack of [Ca(2+)](i) responses in VMFs challenged with the selective P(2Y1) agonists ADPbetaS and 2-Me-S-ATP further supported that functional P(2Y2) receptors are responsible for the Ca(2+) signals. Finally, in a small number of VMFs spontaneous Ca(2+) releases in localized areas were observed. Blockade of the RyR elongated the latency period between each Ca(2+) releasing event, demonstrating the presence of functional RyRs in VMFs.     

SGLT2 inhibitors in the treatment of type 2 diabetes

The kidney plays an important role in glucose homeostasis via its production, utilization, and, most importantly, reabsorption of glucose from glomerular filtrate which is largely mediated via the sodium glucose co-transporter 2 (SGLT2). Pharmacological inhibition of SGLT2 increases urinary glucose excretion and decreases plasma glucose levels in an insulin-independent manner. Agents that inhibit SGLT2 represent a novel class of drugs, which has recently become available for treatment of type 2 diabetes. This article summarizes the rationale for use of these agents and reviews available clinical data on their efficacy, safety, and risks/benefits.     

Mutations in the AGXT2L2 gene cause phosphohydroxylysinuria

Phosphohydroxylysinuria has been described in two patients with neurological symptoms, but the deficient enzyme or mutated gene has never been identified. In the present work, we tested the hypothesis that this condition is due to mutations in the AGXT2L2 gene, recently shown to encode phosphohydroxylysine phospholyase. DNA analysis from a third patient, without neurological symptoms, but with an extreme hyperlaxicity of the joints, shows the existence of two mutations, p. Gly240Arg and p.Glu437Val, both in the heterozygous state. Sequencing of cDNA clones derived from fibroblasts mRNA indicated that the two mutations were allelic. Both mutations replace conserved residues. The mutated proteins were produced as recombinant proteins in Escherichia coli and HEK293T cells and shown to be very largely insoluble, whereas the wild-type one was produced as a soluble and active protein. We conclude that phosphohydroxylysinuria is due to mutations in the AGXT2L2 gene and the resulting lack of activity of phosphohydroxylysine phospholyase in vivo. The finding that the nul alleles of p.Gly240Arg and p.Glu437Val are present at low frequencies in the European and/or North American population suggests that this condition is more common than previously thought. The diversity of the clinical symptoms described in three patients with phosphohydroxylysinuria indicates that this is most likely not a neurometabolic disease.     

SGLT-2 inhibitors in development for type 2 diabetes treatment

The prevalence of type 2 diabetes is increasing worldwide. The majority of currently available glucose-lowering agents work via insulin-dependent mechanisms and have significant limitations. Hence, there is a need for newer treatments utilizing novel therapeutic targets. Drugs which inhibit the sodium glucose cotransporter in the renal tubules (SGLT-2 inhibitors), represent a novel class of drugs under development. By inhibiting SGLT-2, they promote increased renal glucose excretion and thereby calorie loss with improved glycemic control and weight loss. Dapagliflozin is most advanced in development of this new drug class and currently undergoing phase 3 trials. In addition to its glucose lowering effect, dapagliflozin appears to have favorable impacts on weight and blood pressure, with low risk of hypoglycemia. However, as with all new treatments, long-term safety is an issue. Clinical trials showed increased risk of genital and possibly urinary infections with dapgliflozin. Furthermore, concerns have arisen regarding a possible increased incidence of breast and bladder cancer in patients on dapagliflozin. However, it needs further investigation to confirm or refute whether these concerns are concrete.     

Haptoglobin 2-2 phenotype is a risk factor for type 2 diabetes in Ghana

We have investigated the role of haptoglobin gene polymorphisms in 129 type 2 diabetic patients and 87 non-diabetic subjects, classified by the ADA criteria, in Ghana. The diabetic subjects were recruited consecutively from the National Diabetic Management and Research Center of the University of Ghana Medical School, Korle-Bu, Accra, Ghana and were categorized by their haptoglobin phenotypes. The haptoglobin 2 allele was determined to be a risk factor for type 2 diabetes in Ghana (OR = 6.1, 95% CI = 1.8-21.2; P = .0.001) while the Hp1 allele appeared protective (OR = 0.56, 95% CI = 0.31-1.0; P = .06). The deleterious role of the Hp2 allele was further evidenced by the reduced risk associated with Hp2-1M mutant heterozygotes, who produce less Hp2 protein than the normal Hp2-1 heterozygote. (OR = 0.52, 95% CI = 0.27-1.0; P = 0.06). The subjects with the homozygous Hp2 allele were also hypertensive and overweight. There was no difference (p > 0.05) in the levels of triglycerides, total cholesterol, LDL and HDL between diabetic subjects with different haptoglobin phenotypes.We conclude that hypertensive and overweight individuals with the Hp2-2 phenotype in Ghana are at a high risk of developing type 2 diabetes and may require a more aggressive management.     

ALDH2/ADH2 Polymorphism Associated with Vasculopathy and Neuropathy in Type 2 Diabetes

In the history of diabetes, chlorpropamide alcohol flushing test (CPAF) was a big topic in the 1970s to 1980s. Alcohol tolerance after chlorpropamide has prognostic significance, with the intolerant group (CPAF-positive group) being less prone to develop vascular complication than the tolerant group (CPAF-negative group). A mechanism of CPAF has been regarded as the inhibition of aldehyde dehydrogenase 2 (ALDH2) by an N¹-alkyl-substituted derivative of chlorpropamide, and the expression of these mutations of ALDH2 and alcohol dehydrogenase 2 (ADH2) could determine the alcohol tolerance among the Japanese population. Therefore, we hypothesized that expression of different ALDH2 and ADH2 polymorphisms may induce differences in vascular complications in diabetes and conducted two studies. The first study (study 1) was to determine the association of ALDH2/AHD2 polymorphism with diabetic complications. To know the association of ALDH2/AHD2 polymorphism with diabetic vasculopathy and neuropathy, a total of 158 patients with type 2 diabetes were divided into four groups on the basis of ALDH2 "activity" and ADH2 "superactivity." The frequency of proteinuria and the percentage of proliferative retinopathy among the patients with retinopathy was higher in those with active ALDH2 and superactive ADH2. We speculated that protein kinase C isoforms up-regulated by 4-hydroxynonenal that was detoxified by ALDH2 and ADH2 may account for the long-term development of diabetic nephropathy and severe retinopathy. As for neuropathy, the frequency of symptomatic neuropathy was higher in patients with inactive ALDH2 and usual ADH2. We speculate that increased tissue levels of toxic aldehyde could result from inactive ALDH2 and usual ADH2 expression, which results in the increased level of reactive aldehyde in sensory neuron pathway, thereby causing symptomatic polyneuropathy.