[The efficacy and prognostic factors of immunotherapy in advanced non-small cell lung cancer patients with different driver gene mutations].

Objective: To explore the efficacy and prognostic factors of immunotherapy in advanced non-small cell lung cancer (NSCLC) patients with different driver gene mutations. Methods: Medical records of advanced NSCLC patients who harbored driver gene mutations (EGFR, KRAS, ALK and etc.) and received PD-1 inhibitors in Henan Cancer Hospital from April 2016 to May 2021 were collected. Treatment patterns, progression free survival (PFS), overall survival (OS) and prognostic factors of patients with driver gene mutations were estimated. Results: A total of 120 patients were included. There were 70 males and 50 females, with a median age [M(Q1,Q3)] of 57 (50, 65) years. Of these, 52 patients harbored KRAS mutations, 42 patients harbored EGFR mutations, 16 patients harbored ERBB2 mutations, 5 patients harbored MET mutations or amplifications, 5 patients harbored ROS-1 mutations, 2 patients harbored BRAF mutations, and the last 2 patients harbored ALK and RET mutations, respectively. The PFS and OS [M (95%CI)] were 6.4 (5.1-7.8) and 31.2 (22.0-40.3) months in 120 participated patients. Patients with KRAS mutations showed the greatest survival benefit from Immune checkpoint inhibitors (ICIs) with the PFS of 9.7 (4.8-14.6) months and OS of 31.2 (19.4-50.6) months. They mostly received the first-line (34.6%, 18/52) and second-line (38.5%, 20/52) ICIs. The PFS and OS of EGFR mutant patients were 3.9 (1.8-6.1) months and 18.0 (12.1-23.8) months, respectively. They tended to receive ICIs after resistance to EGFR-tyrosine kinase inhibitors (TKIs), and the proportion of second-, third-, fourth or further-line drugs was 38.1% (16/42), 11.9% (5/42), and 47.6% (20/42), respectively. PD-L1 expression level (negative vs ≥50% positive: HR=3.710, 95%CI: 1.372-10.031, P=0.010; 1%-49% positive vs ≥50% positive: HR=2.738, 95%CI: 0.841-8.912, P=0.094), age (every additional year: HR=0.957, 95%CI: 0.933-0.982, P=0.001) and different driver mutations status (EGFR vs KRAS: HR=2.676, 95%CI: 1.317-5.436, P=0.006; ERBB2 vs KRAS: HR=3.411, 95%CI: 1.493-7.792, P=0.004; other mutations vs KRAS: HR=0.727, 95%CI: 0.322-1.643, P=0.444) were prognostic factors for PFS. While PD-L1 expression level (negative vs ≥50% positive: HR=2.305, 95%CI: 0.748-7.103, P=0.146; 1%-49% positive vs ≥50% positive: HR=1.286, 95%CI: 0.337-4.913, P=0.713), and treatment lines of ICIs (first-line vs ≥ third-line: HR=0.322, 95%CI: 0.114-0.914, P=0.033; second-line vs ≥ third-line: HR=0.375, 95%CI: 0.178-0.789, P=0.010) were prognostic factors for OS. Conclusions: KRAS mutant NSCLC patients mostly receive ICIs at the front line, and have best survival benefits from immunotherapy. While EGFR mutant NSCLC patients tend to receive ICIs at the back line, and obtain reasonable survival benefits. PD-L1 expression level, age, and different driver mutations status are prognostic factors for PFS, and PD-L1 expression level and treatment lines of ICIs are prognostic factors for OS.

Investigation of the relationships among respiratory syncytial virus infection, T cell immune response and intestinal flora.

The aim of this work was to evaluate the relationships among respiratory syncytial virus infection, T cell immune response and intestinal flora. Peer-reviewed papers published in English were collected through extensive searches performed in PubMed, Web of Science, Google Scholar, and China National Knowledge Infrastructure databases. The articles were reviewed to extract relevant information on the immune responses of Th1/Th2 and Treg/Th17 to respiratory syncytial virus infection in the body. RSV (Respiratory syncytial virus, RSV) infection leads to imbalance between Th1/Th2 and Treg/Th17 immune cells, resulting in Th2 or Th17 dominant immune responses, which can generate immune disorder and aggravate clinical symptoms. Intestinal micro-organisms play very important roles in maintaining stable immune environment, stimulating immune system maturation and balancing Th1/Th2 and Treg/Th17 immune systems in children. In our review of various papers from around the world, we speculated that the steady state of intestinal bacteria was disturbed after children got infected with RSV, resulting in intestinal flora disorder. Then, the imbalance between Th1/Th2 and Treg/Th17 immune cells was increased. Both intestinal flora disorder and RSV infection could cause cellular immunity imbalance of Th1/Th2 or Treg/Th17, eventually leading to disease deterioration and even a vicious cycle. Normal intestinal flora can maintain immune system stability, regulate the dynamic balance of Th1/Th2 and Treg/Th17 and prevent or mitigate adverse consequences of RSV infection. Because probiotics can improve intestinal barrier function and regulate immune response, they can effectively be used to treat children with recurrent respiratory tract infections. Using conventional antiviral therapy strategy supplemented with probiotics in the treatment of clinical RSV infection may be better for the body.

Effects of methionine hydroxyl analog chelated zinc on laying performance, eggshell quality, eggshell mineral deposition, and activities of Zn-containing enzymes in aged laying hens.

The study aimed to determine the effects of methionine hydroxyl analog chelated zinc (MHA-Zn) on laying performance, eggshell quality and mineral deposits, and the activities of Zn-containing enzymes on aged laying hens. A total of 960 layers (Hy-Line Grey, 57 wk old) were fed a basal diet (Zn: 35.08 mg/kg) without extra zinc for 2 wk. During the ensuing 14 wk, birds were randomly divided into 4 groups according to body weight and laying rate, with 8 replicates per treatment, and each group had 8 replicates of 30 hens. Four levels of Zn (ZnSO4: 80 mg/kg; MHA-Zn: 20, 40, 80 mg/kg) were added to the diet, respectively. The results shown that dietary Zn did not affect laying rate, average egg weight, average daily feed intake, or feed conversion ratio (P > 0.05); however, compared to the inorganic group, dietary supplementation with 40 or 80 mg/kg MHA-Zn decreased broken egg rate significantly in the whole period (P < 0.05), while significantly increased eggshell weight in week 62 to 72, eggshell thickness and eggshell strength in wk 66 to 72, eggshell weight percent and eggshell density in week 62 to 72 (P < 0.05). Besides, dietary supplementation with different sources and levels of Zn did not affect ash concentration of eggshell (P > 0.05), whereas dietary supplementation with 80 mg/kg MHA-Zn improved the Zn and Ca concentrations of eggshells and carbonic anhydrase (CA) activity of liver, and 40 mg/kg MHA-Zn increased Zn concentration of liver (P < 0.05). Moreover, no significant differences in alkaline phosphatase activity were observed among the treatment groups (P > 0.05). Therefore, dietary supplementation with 40 mg/kg MHA-Zn can improve eggshell quality by promoting Ca deposition and CA activity.

Involvement of the Nrf2/HO-1 signaling pathway in sulfuretin-induced protection against amyloid beta25-35 neurotoxicity.

Sulfuretin, one of the major flavonoid glycosides found in the stem bark of Albizzia julibrissin and heartwood of Rhus verniciflua, is a known anti-oxidant. We previously demonstrated that sulfuretin inhibits neuronal death via reactive oxygen species (ROS)-dependent mechanisms in human SH-SY5Y cells, although other relevant mechanisms of action of this compound remain largely uncharacterized. As part of our ongoing exploration of the pharmacological actions of sulfuretin, we studied the neuroprotective effects of sulfuretin against amyloid beta (Aß)-induced neurotoxicity in human SH-SY5Y and primary hippocampal neuron cells and investigated the possible mechanisms involved. Specifically, we found in the present study that sulfuretin significantly attenuates the decrease in cell viability, release of lactate dehydrogenase, and accumulation of ROS associated with Aß25-35-induced neurotoxicity in neuronal cells. Furthermore, sulfuretin stimulated the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a downstream target of phosphatidylinositol 3-kinases (PI3K)/Akt. We demonstrated that sulfuretin induces the expression of heme oxygenase-1 (HO-1), an anti-oxidant response gene. Notably, we found that the neuroprotective effects of sulfuretin were diminished by an Nrf2 small interfering RNA (siRNA), the HO-1 inhibitor zinc protoporphyrin IX (ZnPP), as well as the PI3K/Akt inhibitor LY294002. Taken together, these results indicated that sulfuretin protects neuronal cells from Aß25-35-induced neurotoxicity through activation of Nrf/HO-1 and PI3K/Akt signaling pathways. Our results also indicate that sulfuretin-induced induction of Nrf2-dependent HO-1 expression via the PI3K/Akt signaling pathway has preventive and/or therapeutic potential for the management of Alzheimer's disease.

Increased expression of nitric oxide synthase in the gracile nucleus of aged rats.

Aging is associated with disturbances in autonomic cardiovascular control. The purpose of this study was to test the hypothesis that changes in nitric oxide occur with aging in brainstem nuclei involved in autonomic cardiovascular control. The principal and unexpected finding in this study was that NADPH-diaphorase reactivity, which is considered a marker of neuronal nitric oxide synthase activity, was decidedly increased in the neuronal bodies of the gracile nucleus but decreased in the axons and axon terminals in old compared with young rats. In situ hybridization also revealed that nitric oxide synthase gene expression was enhanced predominantly in the gracile nucleus neurons of aged rats. The differences between the young and old rats were most dramatically evident in the gracile nucleus, but not evident in other brainstem nuclei. The significance of this finding as it might relate to autonomic or other specific neural dysfunction with aging is not evident at this time.

Central noradrenergic activity is responsible for nitroglycerin-induced cardiovascular effects in the nucleus tractus solitarii.

The studies show that unilateral microinjection of nitroglycerin (NTG) into nucleus tractus solitarii (NTS) produce dose-dependent decreases in mean arterial pressure (MAP) and heart rate, but injection of sodium nitroprusside (SNP) into the area induced slight effects. Hypotensive responses to NTG injected into the NTS showed that the compound was 20 times more potent than after i.v. administration. Responses to NTG injected into the NTS were abolished in an additive fashion by either rauwolscine, an alpha 2-adrenoceptor antagonist, or guanethidine which inhibits release of norepinephrine (NE). Injection of prazosin, an alpha 1-adrenoceptor antagonist, into the NTS reduced the hypotensive responses of NTG, but did not alter the bradycardia induced by the drug. Tachycardic responses following i.v. administration of either NTG or SNP were attenuated by bilateral injection of rauwolscine into the NTS, whereas only hypotensive responses to i.v. NTG were reduced by the pretreatment. NTG produced a dose-dependent increase in concentrations of 3,4-dihydroxyphenylalanine in media bathing medulla-pons, which were quantified using high-performance liquid chromatography with electrochemical detection. NE and 3,4-dihydroxyphenylglycol concentrations in media of incubated medulla-pons slices were simultaneously increased following higher concentrations of NTG. The results suggest that NTG in the NTS induces hypotensive and bradycardiac responses, and an increase in turnover of NE may stimulate alpha 2-adrenoceptors and be responsible for the effects of the drug. The NTS may contribute a component of action to the cardiovascular effects of intravenous NTG. The cardiovascular responses of intravenous SNP appear to involve peripheral action.

Effects of nitroglycerin on release, synthesis and metabolism of norepinephrine and activation of tyrosine hydroxylase in guinea-pigs.

Nitroglycerin produced concentration-dependent increases in outflow of norepinephrine (NE) in perfused guinea-pig hearts. These effects of nitroglycerin were inhibited by guanethidine, but were not blocked by desmethylimipramine or rauwolscine. Nitroglycerin-induced increases in NE outflow correlated with its positive chronotropic responses. Higher concentrations of nitroglycerin also increased outflow of 3,4-dihydroxyphenylglycol (DOPEG) which were inhibited by desmethylimipramine. Nitroglycerin-induced maximal outflow of NE occurred during the first 2 min, but maximal outflow of DOPEG was 2-4 min. In addition, the 3,4-dihydroxyphenylalanine formation in atrial and striatal slices were enhanced by nitroglycerin in the presence of m-hydroxybenzylhydrazine dihydrochloride (an inhibitor of aromatic L-amino acid decarboxylase). The results suggest that nitroglycerin increases release of NE which correlates with cardiac stimulation by the drug. The drug also stimulates tyrosine hydroxylase activity resulting in increased synthesis of NE.

Noradrenergic mechanisms and the cardiovascular actions of nitroglycerin.

In this article we review noradrenergic activities of nitroglycerin in the central and peripheral nervous systems. Nitroglycerin may cause paradoxical bradycardia and occasional life threatening hypotension in patients. Intracisternal injections and microinjections of nitroglycerin into nucleus tractus solitarii produce hypotension and bradycardia, effects which mimic the baroreflex and may involve central noradrenergic mechanisms. The drug also triggers an alpha 2-adrenoceptor-mediated sympatho-inhibition reflex through vagal afferents. Nitroglycerin mimics biological responses associated with sympathetic neuronal activity, e.g., increase in outflow of norepinephrine and its metabolites from perfused guinea pig atria, medulla-pons tissue and cerebrospinal fluid. The sympathomimetic effects of nitroglycerin are antagonized by pre-treatment with yohimbine or rauwolscine. Clinical studies and animal experiments show that hemodynamics of nitroglycerin and sodium nitroprusside are different. Nitroglycerin is lipophilic and the compounds readily enters cells to form nitric oxide, but sodium nitroprusside is very hydrophilic and the compound has difficulty crossing membranes. Thus, intravenous nitroglycerin-induced increases in central noradrenergic activation and inhibitory reflexes may account for at least some of the therapeutic actions and side effects of the drug. In contrast, minimal central responses are produced by intravenous administration of sodium nitroprusside.

[Proton inducted X-ray emission analysis of food samples].

PIXE (Proton inducted X-ray emission) analysis of food samples was carried out with 2 Mev protons. The measured seven trace elements for 62 food samples are listed in tables.

Positive chronotropic and inotropic responses to release of norepinephrine from sympathetic nerve terminals produced by nitroglycerin in atria.

Nitroglycerin produced concentration-dependent increases in spontaneous rate and enhancements of positive chronotropic and inotropic responses to transmural stimulation of isolated right guinea-pig atria. The effects of nitroglycerin were significantly potentiated by desmethylimipramine, which is an inhibitor of norepinephrine uptake, and were significantly inhibited by either guanethidine, which inhibits release of norepinephrine, or alpha-methyl-p-tyrosine, which inhibits synthesis of norepinephrine. The effects of nitroglycerin were not modified by either prazosin or atropine, but were significantly inhibited by either the beta-adrenoceptor antagonist propranolol or the alpha 2-adrenoceptor antagonist yohimbine. Nitroglycerin significantly increased the concentration of norepinephrine in the medium bathing atria and the 3,4-dihydroxyphenylglycol concentration in the atrial tissue, which were quantified using high-performance liquid chromatography with electrochemical detection. The atrial responses to nitroglycerin appear to mimic sympathetic neuronal activities and may involve the modulatory role of alpha 2-adrenoceptors in the release of norepinephrine.

Derivatives of 4-(2-N,N-di-n-propylaminoethyl)-5-hydroxyindole: synthesis and pharmacological effects.

5-Methoxy-1-methyl-4-(2-N,N-di-n-propylaminoethyl)indole (12) was synthesized from 5-hydroxyindole by a multistep synthesis. This target compound was designed as a bioisostere of "p-dimethoxy" catechol congeners of dopaminergic agonists derived from a variety of ring systems, in some of which p-dimethoxy-substituted systems are potent, active dopaminergic agonists. To complete the indole series, all possible combinations of N- and O-demethylated derivatives of 12 were prepared and were also evaluated pharmacologically. All members of this indole-derived series showed a low order of cardiovascular activity, which appeared to be independent of dopamine receptors. The lack of dopaminergic activity of 12 is cited as yet another example of the unpredictable effect of replacement of the catechol moiety of a dopaminergic agonist with a p-dimethoxy moiety.

Nitric oxide modulates angiotensin II-induced drinking behavior in the near-term ovine fetus.

OBJECTIVE: Human and ovine fetuses demonstrate an enhanced rate of spontaneous and angiotensin II-stimulated swallowing. Angiotensin II and nitric oxide synthase have been localized to thirst centers in the brain. This study was performed to determine whether central nitric oxide contributes to the regulation of angiotensin II-induced fetal swallowing. STUDY DESIGN: Six pregnant ewes with near-term singleton fetuses were chronically prepared with fetal vascular and lateral ventricle catheters and electrocorticogram and esophageal electromyogram electrodes. After a 2-hour control period, fetuses were administered serial lateral ventricle injections (1 mL) of angiotensin II (3.2 microg; time, 2 hours) and N omega-nitro-L -arginine methyl ester (3 mg; time, 3 hours) and a repeat angiotensin II injection (3.2 microg; time, 5 hours). All fetuses received an additional control study of lateral ventricle injections of artificial cerebrospinal fluid on a previous day. RESULTS: Angiotensin II injection significantly increased mean +/- SEM fetal swallowing (0.9 +/- 0.1 to 2.7 +/- 0.4 swallows/min). N omega-nitro-L -arginine methyl ester significantly decreased fetal swallowing to below the basal rate (0.4 +/- 0.1 swallows/min), and swallowing did not increase with the second angiotensin II dose (in the presence of nitric oxide blockade). CONCLUSIONS: These results demonstrate that inhibition of central nitric oxide suppresses fetal swallowing behavior in response to central angiotensin II. We speculate that tonic nitric oxide facilitates angiotensin II swallowing stimulation by maintenance of glutamate activation of hypothalamic N -methyl-D -aspartate receptors.

Nitric oxide modulates spontaneous swallowing behavior in near-term ovine fetus.

Human and ovine fetuses demonstrate an enhanced rate of swallowing, an activity critical for amniotic fluid regulation. Fetal swallowing may be modulated by both systemic and central factors. Nitric oxide (NO) is a central neuromodulator that has been localized to brain regions regulating thirst and swallowing. We sought to determine if NO contributes to the regulation of spontaneous ovine fetal swallowing. Six time-dated pregnant ewes with singleton fetuses (129 +/- 1 day) were chronically prepared with fetal vascular and lateral ventricle catheters and electrocorticogram (ECoG) and esophageal electromyogram electrodes. After a 2-h control period, fetuses were given lateral ventricle injection of NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME) and monitored for 2 h. NO precursor L-arginine was then injected into the lateral ventricle, and fetuses were monitored for a final 2 h. All fetuses received an additional control study of fetal swallowing before and after lateral ventricle injection of artificial cerebrospinal fluid (aCSF). Data were analyzed with repeated-measures ANOVA and paired t-test (P < 0.05). Suppression of a central NO with central L-NAME significantly reduced mean (+/-SE) spontaneous fetal swallowing (1.2 +/- 0.1-0.6 +/- 0.1 swallows/min low-voltage ECoG; P < 0.01). Restoration of central NO by L-arginine significantly increased fetal swallowing to pre-L-NAME levels (1.2 +/- 0.1 swallows/min low voltage). There were no changes in fetal swallowing during the control study of aCSF. Fetal ECoG activity and blood pressure did not change during the study or control aCSF injection. We conclude that NO is an important neuromodulator of fetal swallowing activity. Central NO synthase activity may contribute to the heightened level of spontaneous fetal swallowing and thus amniotic fluid regulation.

Increased nitric oxide concentrations in posterior hypothalamus and central sympathetic function on nitrate tolerance following subcutaneous nitroglycerin.

The present study was to examine the distributions of nitric oxide (NO) in the brain regions and peripheral vessels following subcutaneously administered nitroglycerin (NTG) and determine the noradrenergic activity and the role of central sympathetic function in acute nitrate tolerance. Tolerance to NTG was produced by subcutaneous (sc) administration of 4.0 mg NTG as four separate hourly pulse injections of 1.0 mg each in male (5-8 months) Sprague-Dawley rats. Rats in sham-treated group received sc injections of saline. Rats were killed by sodium pentobarbital (150 mg/kg, ip) at 10 min after last sc injection. The brain, gracilis muscle, aorta, superior mesenteric artery, coronary artery, and pulmonary vessels were quickly removed. Concentrations of nitrite (NO2-), nitrate (NO3-), and total NO2- plus NO3- (NOx-) were quantified in the micropunches of the anterior hypothalamus, the posterior hypothalamus (PH), the nucleus tractus solitarius, the lateral reticular nucleus, and the vessels in a blinded fashion. The central actions of acute tolerance to NTG were also determined using blockades of sympathetic functions in conscious rats. Four separate hourly pulse sc injections of 1.0 mg NTG produced a marked shift of the dose-response curve for arterial pressure depression induced by intravenous injection of the challenge doses of NTG. The same doses of sc NTG caused increases in NOx- [92+/-16% (mean +/- SE)] and NO3- productions (77+/-15%) in the PH, but did not significantly change in other brain regions (n = 6). NOx- and NO3- productions were significantly enhanced in the superior mesenteric artery, aorta, coronary artery, and pulmonary vessels following sc NTG, but were not altered in gracilis muscle by the treatment. The tolerance responses to arterial pressure depression were attenuated by intravenous administration of either prazosin (300 microg/kg), an alpha1-adrenoceptor antagonist, or chlorisondamine (10 mg/kg), a sympathetic ganglion blockading agent (n = 5-6). The results suggest that acute NTG tolerance predominately increases NO production in the PH. NO production was also markedly enhanced in the large and middle vessels but not in small vessels during acute NTG tolerance. The arterial pressure tolerance to NTG was reversed by blockade of central sympathetic function. We conclude that NO formation is increased in the PH following systemically administered NTG and NO in the PH may facilitate central sympathetic functions which contribute to nitrate tolerance.

Dopaminergic structure-activity relationships of 2-aminoindans and cardiovascular action and dopaminergic activity of 4-hydroxy, 5-methyl, 2-di-n-propylaminoindan (RD-211).

Dopaminergic structure-activity relationships of 2-aminoindans were evaluated for their ability to inhibit responses to stimulation of cardioaccelerator nerves in cats. The major observations were as follows: 1) Unsubstituted di-n-propyl- and diethyl 2-aminoindan derivatives do not inhibit responses to stimulation of cardioaccelerator nerve, although previous studies identified stimulation of DA2-receptors. 2) 4-Hydroxy, 4,7-dimethoxy and 4-hydroxy, 5-CH3, -CH2OH or -H substitutions on selected indan derivatives produce dopaminergic activity in the cardioaccelerator nerve preparation. 3) 4-Hydroxy-2-di-n-propylaminoindan is stereoselective with the R-isomer being more potent than the S-isomer. One derivative, 4-hydroxy-5-methyl-di-n-propyl-2-aminoindan (RD-211) produced dose-dependent decreases in heart rate and mean arterial pressure. Larger doses also inhibited cardiac responses to stimulation of cardioaccelerator nerve in vivo and in isolated right atria of cats. All of the above responses were significantly inhibited by the dopamine-receptor antagonist sulpiride and not by the alpha 2-adrenoceptor antagonist yohimbine. RD-211 also possesses high affinity for 5-hydroxytryptamine1A receptors as revealed by radioligand binding studies. Results suggest that RD-211 stimulates dopamine DA2-receptors and may also activate 5-hydroxytryptamine1A receptors, but is inactive at alpha 2-adrenoceptors. RD-211 appears not to require metabolic activation even though it has the same chemical moiety as the aminotetralin homolog, which is a dopaminergic prodrug (5-hydroxy-6-methyl-2-di-n-propylaminotetralin).

Regulation of phospholipase C-gamma(1) by the actin-regulatory protein villin.

The actin-regulatory protein villin is tyrosine phosphorylated and associates with phospholipase C-gamma(1) (PLC-gamma(1)) in the brush border of intestinal epithelial cells. To study the mechanism of villin-associated PLC-gamma(1) activation, we reconstituted in vitro the tyrosine phosphorylation of villin and its association with PLC-gamma(1). Recombinant villin was phosphorylated in vitro by the nonreceptor tyrosine kinase c-src or by expression in the TKX1 competent cells that carry an inducible tyrosine kinase gene. Using in vitro binding assays, we demonstrated that tyrosine-phosphorylated villin associates with the COOH-terminal Src homology 2 (SH2) domain of PLC-gamma(1). The catalytic activity of PLC-gamma(1) was inhibited by villin in a dose-dependent manner with half-maximal inhibition at a concentration of 12.4 microM. Villin inhibited PLC-gamma(1) activity by sequestering the substrate phosphatidylinositol 4,5-bisphosphate (PIP(2)), since increasing concentrations of PIP(2) reversed the inhibitory effects of villin on PLC activity. The inhibition of PLC-gamma(1) activity by villin was reversed by the tyrosine phosphorylation of villin. Further, we demonstrated that tyrosine phosphorylation of villin abolished villin's ability to associate with PIP(2). In conclusion, tyrosine-phosphorylated villin associates with the COOH-terminal SH2 domain of PLC-gamma(1) and activates PLC-gamma(1) catalytic activity. Villin regulates PLC-gamma(1) activity by modifying its own ability to bind PIP(2). This study provides biochemical proof of the functional relevance of tyrosine phosphorylation of villin and identifies the molecular mechanisms involved in the activation of PLC-gamma(1) by villin.