Dual add-on therapy of gemigliptin and dapagliflozin in patients with type 2 diabetes inadequately controlled with metformin alone: The SOLUTION 2 study.

AIM: To evaluate the efficacy and safety of gemigliptin and dapagliflozin dual add-on therapy (GEMI + DAPA) to metformin in type 2 diabetes (T2D) patients who had inadequate glycaemic control on metformin alone, compared with a single add-on of either gemigliptin (GEMI) or dapagliflozin (DAPA) to metformin. MATERIALS AND METHODS: In this randomized, double-blind, double-dummy, active-controlled, parallel-group, phase 3 study, 469 T2D patients treated with a stable dose of metformin for 8 weeks or longer were randomized to receive GEMI + DAPA (n = 157) and either GEMI (n = 156) or DAPA (n = 156). The primary endpoint was change in HbA1c levels from baseline at week 24. RESULTS: Baseline characteristics including body mass index and T2D duration were similar among groups. At week 24, the least square mean changes in HbA1c from baseline were -1.34% with GEMI + DAPA, -0.90% with GEMI (difference between GEMI + DAPA vs. GEMI -0.44% [95% confidence interval {CI}: -0.58% to -0.31%], P < .01) and -0.78% with DAPA (difference between GEMI + DAPA vs. DAPA -0.56% [95% CI: -0.69% to -0.42%], P < .01). Both upper CIs were less than 0, demonstrating the superiority of GEMI + DAPA for lowering HbA1c. The rates of responders achieving HbA1c less than 7% and less than 6.5% were greater with GEMI + DAPA (84.9%, 56.6%) than with GEMI (55.3%, 32.2%) and DAPA (49.3%, 15.3%). The incidence rate of adverse events was similar across groups, with low incidence rates of hypoglycaemia, urinary tract infection and genital infection. CONCLUSIONS: These results suggest that the addition of GEMI + DAPA to metformin as triple combination therapy was effective, safe and well-tolerated, especially for T2D patients who experienced poor glycaemic control on metformin alone.

MDGAs perform activity-dependent synapse type-specific suppression via distinct extracellular mechanisms.

MDGA (MAM domain containing glycosylphosphatidylinositol anchor) family proteins were previously identified as synaptic suppressive factors. However, various genetic manipulations have yielded often irreconcilable results, precluding precise evaluation of MDGA functions. Here, we found that, in cultured hippocampal neurons, conditional deletion of MDGA1 and MDGA2 causes specific alterations in synapse numbers, basal synaptic transmission, and synaptic strength at GABAergic and glutamatergic synapses, respectively. Moreover, MDGA2 deletion enhanced both N-methyl-D-aspartate (NMDA) receptor- and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor-mediated postsynaptic responses. Strikingly, ablation of both MDGA1 and MDGA2 abolished the effect of deleting individual MDGAs that is abrogated by chronic blockade of synaptic activity. Molecular replacement experiments further showed that MDGA1 requires the meprin/A5 protein/PTPmu (MAM) domain, whereas MDGA2 acts via neuroligin-dependent and/or MAM domain-dependent pathways to regulate distinct postsynaptic properties. Together, our data demonstrate that MDGA paralogs act as unique negative regulators of activity-dependent postsynaptic organization at distinct synapse types, and cooperatively contribute to adjustment of excitation-inhibition balance.

The Efficacy and Tolerability of Irbesartan/Amlodipine Combination Therapy in Patients With Essential Hypertension Whose Blood Pressure Were not Controlled by Irbesartan Monotherapy.

PURPOSE: This study aimed to evaluate the efficacy and tolerability of irbesartan (IRB) and amlodipine (AML) combination therapy in patients with essential hypertension whose blood pressure (BP) was not controlled by IRB monotherapy. METHODS: Two multicenter, randomized, double-blind, placebo-controlled, phase III studies were conducted in Korea (the I-DUO 301 study and the I-DUO 302 study). After a 4-week run-in period with either 150 mg IRB (I-DUO 301 study) or 300 mg IRB (I-DUO 302 study), patients with uncontrolled BP (ie, mean sitting systolic BP [MSSBP] ≥140 mmHg to <180 mmHg and mean sitting diastolic BP <110 mmHg) were randomized to the placebo, AML 5 mg, or AML 10 mg group. A total of 428 participants were enrolled in the 2 I-DUO studies. In the I-DUO 301 study, 271 participants were randomized in a 1:1:1 ratio to receive either IRB/AML 150/5 mg, IRB/AML 150/10 mg, or IRB 150 mg/placebo. In the I-DUO 302 study, 157 participants were randomized in a 1:1 ratio to receive IRB/AML 300/5 mg or IRB 300 mg/placebo. The primary endpoint was the change in MSSBP from baseline to week 8. Tolerability was assessed according to the development of treatment-emergent adverse events (TEAEs) and clinically significant changes in physical examination, laboratory tests, pulse, and 12-lead electrocardiography. FINDINGS: In I-DUO 301, the mean (SD) changes of MSSBP at week 8 from baseline were -14.78 (12.35) mmHg, -21.47 (12.78) mmHg, and -8.61 (12.19) mmHg in the IRB/AML 150/5 mg, IRB/AML 150/10 mg, and IRB 150 mg/placebo groups, respectively. In I-DUO 302, the mean (SD) changes of MSSBP at week 8 from baseline were -13.30 (12.47) mmHg and -7.19 (15.37) mmHg in the IRB/AML 300/5 mg and IRB 300 mg/placebo groups, respectively. In both studies, all combination groups showed a significantly higher reduction in MSSBP than the IRB monotherapy groups (P < 0.001 for both). TEAEs occurred in 10.00%, 10.99%, and 12.22% of participants in the IRB/AML 150/5 mg, IRB/AML 150/10 mg, and IRB 150 mg/placebo groups, respectively, in I-DUO 301 and in 6.33% and 10.67% of participants in the IRB/AML 300/5 mg and IRB 300 mg/placebo groups, respectively, in I-DUO 302, with no significant between-group differences. Overall, there was one serious adverse event throughout I-DUO study. IMPLICATIONS: The combination of IRB and AML has superior antihypertensive effects compared with IRB alone over an 8-week treatment period, with placebo-like tolerability. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT05476354 (I-DUO 301), NCT05475665 (I-DUO 302).

Efficacy and Safety of Alogliptin-Pioglitazone Combination for Type 2 Diabetes Mellitus Poorly Controlled with Metformin: A Multicenter, Double-Blind Randomized Trial.

Background: Guidelines for switching to triple combination therapy directly after monotherapy failure are limited. This study investigated the efficacy, long-term sustainability, and safety of either mono or dual add-on therapy using alogliptin and pioglitazone for patients with type 2 diabetes mellitus (T2DM) who did not achieve their target glycemic range with metformin monotherapy. Methods: The Practical Evidence of Antidiabetic Combination Therapy in Korea (PEAK) was a multicenter, placebo-controlled, double-blind, randomized trial. A total of 214 participants were randomized to receive alogliptin+pioglitazone (Alo+Pio group, n=70), alogliptin (Alo group, n=75), or pioglitazone (Pio group, n=69). The primary outcome was the difference in glycosylated hemoglobin (HbA1c) levels between the three groups at baseline to 24 weeks. For durability, the achievement of HbA1c levels <7% and <6.5% was compared in each group. The number of adverse events was investigated for safety. Results: After 24 weeks of treatment, the change of HbA1c in the Alo+Pio, Alo, and Pio groups were -1.38%±0.08%, -1.03%±0.08%, and -0.84%±0.08%, respectively. The Alo+Pio group had significantly lower HbA1c levels than the other groups (P=0.0063, P<0.0001) and had a higher proportion of patients with target HbA1c achievement. In addition, insulin sensitivity and ß-cell function, lipid profiles, and other metabolic indicators were also improved. There were no significant safety issues in patients treated with triple combination therapy. Conclusion: Early combination triple therapy showed better efficacy and durability than the single add-on (dual) therapy. Therefore, combination therapy with metformin, alogliptin, and pioglitazone is a valuable early treatment option for T2DM poorly controlled with metformin monotherapy.

A 52-week efficacy and safety study of enavogliflozin versus dapagliflozin as an add-on to metformin in patients with type 2 diabetes mellitus: ENHANCE-M extension study.

AIM: To evaluate the long-term safety and efficacy of enavogliflozin 0.3 mg/day added to metformin in patients with type 2 diabetes mellitus. MATERIALS AND METHODS: After 24 weeks of a randomized, double-blind treatment period with enavogliflozin 0.3 mg/day (n = 101) or dapagliflozin 10 mg/day (n = 99) added to metformin, all patients received enavogliflozin 0.3 mg/day plus metformin for an additional 28 weeks during the open-label extension period. RESULTS: Eighty-two patients continued enavogliflozin (maintenance group), and 77 were switched from dapagliflozin to enavogliflozin (switch group). All adverse drug reactions (ADR) were mild in severity. In the maintenance group, ADRs (cystitis and vaginal infection) were reported in two patients (2.44%) during 52 weeks. In the switch group, ADR (hypoglycaemia) was reported in one patient (1.30%) during a 28-week open-label extension period. At week 52, glycated haemoglobin and fasting plasma glucose were significantly lower than at the baseline, by 0.85% and 29.08 mg/dl, respectively, in the maintenance group (p < .0001 for both), and by 0.81% and 32.77 mg/dl, respectively, in the switch group (p < .0001 for both). At week 52, 68.92% of patients from the maintenance group and 64.29% from the switch group achieved glycated haemoglobin <7%. A significant increase in the urine glucose-creatinine ratio was observed at week 52, by 58.81 g/g and 63.77 g/g in the maintenance and switch groups, respectively (p < .0001). CONCLUSIONS: Enavogliflozin added to metformin was tolerated well for up to 52 weeks and provided continual glycaemic control in type 2 diabetes mellitus, along with a significant increase in the urine glucose-creatinine ratio.

Specification of neural circuit architecture shaped by context-dependent patterned LAR-RPTP microexons.

LAR-RPTPs are evolutionarily conserved presynaptic cell-adhesion molecules that orchestrate multifarious synaptic adhesion pathways. Extensive alternative splicing of LAR-RPTP mRNAs may produce innumerable LAR-RPTP isoforms that act as regulatory "codes" for determining the identity and strength of specific synapse signaling. However, no direct evidence for this hypothesis exists. Here, using targeted RNA sequencing, we detected LAR-RPTP mRNAs in diverse cell types across adult male mouse brain areas. We found pronounced cell-type-specific patterns of two microexons, meA and meB, in Ptprd mRNAs. Moreover, diverse neural circuits targeting the same neuronal populations were dictated by the expression of different Ptprd variants with distinct inclusion patterns of microexons. Furthermore, conditional ablation of Ptprd meA+ variants at presynaptic loci of distinct hippocampal circuits impaired distinct modes of synaptic transmission and objection-location memory. Activity-triggered alterations of the presynaptic Ptprd meA code in subicular neurons mediates NMDA receptor-mediated postsynaptic responses in CA1 neurons and objection-location memory. Our data provide the evidence of cell-type- and/or circuit-specific expression patterns in vivo and physiological functions of LAR-RPTP microexons that are dynamically regulated.

Pioglitazone as Add-on THERAPY in Patients with Type 2 Diabetes Mellitus Inadequately Controlled with Dapagliflozin and Metformin: Double-Blind, Randomized, Placebo-Controlled Trial.

Background: This study assessed the efficacy and safety of triple therapy with pioglitazone 15 mg add-on versus placebo in patients with type 2 diabetes mellitus (T2DM) inadequately controlled with metformin and dapagliflozin. Methods: In this multicenter, double-blind, randomized, phase 3 study, patients with T2DM with an inadequate response to treatment with metformin (≥1,000 mg/day) plus dapagliflozin (10 mg/day) were randomized to receive additional pioglitazone 15 mg/day (n=125) or placebo (n=125) for 24 weeks. The primary endpoint was the change in glycosylated hemoglobin (HbA1c) levels from baseline to week 24 (ClinicalTrials.gov identifier: NCT05101135). Results: At week 24, the adjusted mean change from baseline in HbA1c level compared with placebo was significantly greater with pioglitazone treatment (-0.47%; 95% confidence interval, -0.61 to -0.33; P<0.0001). A greater proportion of patients achieved HbA1c <7% or <6.5% at week 24 with pioglitazone compared to placebo as add-on to 10 mg dapagliflozin and metformin (56.8% vs. 28% for HbA1c <7%, and 23.2% vs. 9.6% for HbA1c <6.5%; P<0.0001 for all). The addition of pioglitazone also significantly improved triglyceride, highdensity lipoprotein cholesterol levels, and homeostatic model assessment of insulin resistance levels, while placebo did not. The incidence of treatment-emergent adverse events was similar between the groups, and the incidence of fluid retention-related side effects by pioglitazone was low (1.5%). Conclusion: Triple therapy with the addition of 15 mg/day of pioglitazone to dapagliflozin plus metformin was well tolerated and produced significant improvements in HbA1c in patients with T2DM inadequately controlled with dapagliflozin plus metformin.

Efficacy and Safety of Evogliptin Add-on Therapy to Dapagliflozin/Metformin Combinations in Patients with Poorly Controlled Type 2 Diabetes Mellitus: A 24-Week Multicenter Randomized Placebo-Controlled Parallel-Design Phase-3 Trial with a 28-Week Extension.

BACKGRUOUND: This study investigates the long-term efficacy and safety of evogliptin add-on therapy in patients with inadequately controlled type 2 diabetes mellitus (T2DM) previously received dapagliflozin and metformin (DAPA/MET) combination. METHODS: In this multicenter randomized placebo-controlled phase 3 trial, patients with glycosylated hemoglobin (HbA1c) levels 7.0% to 10.5% (n=283) previously used DAPA 10 mg plus MET (≥1,000 mg) were randomly assigned to the evogliptin 5 mg once daily or placebo group (1:1). The primary endpoint was the difference in the HbA1c level from baseline at week 24, and exploratory endpoints included the efficacy and safety of evogliptin over 52 weeks (trial registration: ClinicalTrials.gov NCT04170998). RESULTS: Evogliptin add-on to DAPA/MET therapy was superior in HbA1c reduction compared to placebo at weeks 24 and 52 (least square [LS] mean difference, -0.65% and -0.55%; 95% confidence interval [CI], -0.79 to -0.51 and -0.71 to -0.39; P<0.0001). The proportion of patients achieving HbA1c <7% was higher in the triple combination group at week 52 (32.14% vs. 8.51% in placebo; odds ratio, 5.62; P<0.0001). Evogliptin significantly reduced the fasting glucose levels and mean daily glucose levels with improvement in homeostatic model assessment of ß-cell function (LS mean difference, 9.04; 95% CI, 1.86 to 16.21; P=0.0138). Adverse events were similar between the groups, and no serious adverse drug reactions were reported in the evogliptin group. CONCLUSION: Long-term triple combination with evogliptin added to DAPA/MET showed superior HbA1c reduction and glycemic control compared to placebo at 52 weeks and was well tolerated.

Orchestration of synaptic functions by WAVE regulatory complex-mediated actin reorganization.

The WAVE regulatory complex (WRC), composed of five components-Cyfip1/Sra1, WAVE/Scar, Abi, Nap1/Nckap1, and Brk1/HSPC300-is essential for proper actin cytoskeletal dynamics and remodeling in eukaryotic cells, likely by matching various patterned signals to Arp2/3-mediated actin nucleation. Accumulating evidence from recent studies has revealed diverse functions of the WRC in neurons, demonstrating its crucial role in dictating the assembly of molecular complexes for the patterning of various trans-synaptic signals. In this review, we discuss recent exciting findings on the physiological role of the WRC in regulating synaptic properties and highlight the involvement of WRC dysfunction in various brain disorders.

Efficacy and safety of enavogliflozin, a novel SGLT2 inhibitor, in Korean people with type 2 diabetes: A 24-week, multicentre, randomized, double-blind, placebo-controlled, phase III trial.

AIMS: To evaluate the efficacy and safety of a novel sodium-glucose cotransporter 2 inhibitor, enavogliflozin 0.3 mg monotherapy, in Korean people with type 2 diabetes mellitus (T2DM) inadequately controlled with diet and exercise. MATERIALS AND METHODS: This study was a randomized, double-blind, placebo-controlled trial conducted in 23 hospitals. Individuals with haemoglobin A1c (HbA1c) of 7.0%-10.0% after at least 8 weeks of diet and exercise modification were randomized to receive enavogliflozin 0.3 mg (n = 83) or placebo (n = 84) for 24 weeks. The primary outcome was a change in HbA1c at week 24 from baseline. Secondary outcomes included the proportion of participants achieving HbA1c <7.0%, change in fasting glucose, body weight and lipid levels. Adverse events were investigated throughout the study. RESULTS: At week 24, the placebo-adjusted mean change in HbA1c from baseline in the enavogliflozin group was -0.99% (95% confidence interval -1.24%, -0.74%). The proportions of patients achieving HbA1c <7.0% (71% vs. 24%) at week 24 was significantly higher in the enavogliflozin group (p < .0001). Placebo-adjusted mean changes in fasting plasma glucose (-40.1 mg/dl) and body weight (-2.5 kg) at week 24 were statistically significant (p < .0001). In addition, a significant decrease in blood pressure, low-density lipoprotein cholesterol, triglyceride, and homeostasis model assessment of insulin resistance were observed, along with a significant increase in high-density lipoprotein cholesterol. No significant increase in treatment-related adverse events was observed for enavogliflozin. CONCLUSIONS: Monotherapy with enavogliflozin 0.3 mg improved glycaemic control in people with T2DM. Enavogliflozin therapy also exerted beneficial effects on body weight, blood pressure and lipid profile.

Efficacy and safety of enavogliflozin versus dapagliflozin added to metformin plus gemigliptin treatment in patients with type 2 diabetes: A double-blind, randomized, comparator-active study: ENHANCE-D study.

AIMS: This study evaluated the efficacy and safety of enavogliflozin, a novel sodium-glucose cotransporter 2 inhibitor, versus dapagliflozin in Korean patients with type 2 diabetes mellitus (T2DM) inadequately controlled with metformin and gemigliptin. METHODS: In this multicenter, double-blind, randomized study, patients with inadequate response to metformin (≥ 1000 mg/day) plus gemigliptin (50 mg/day) were randomized to receive enavogliflozin 0.3 mg/day (n = 134) or dapagliflozin 10 mg/day (n = 136) in addition to the metformin plus gemigliptin therapy. The primary endpoint was change in HbA1c from baseline to week 24. RESULTS: Both treatments significantly reduced HbA1c at week 24 (-0.92% in enavogliflozin group, -0.86% in dapagliflozin group). The enavogliflozin and dapagliflozin groups did not differ in terms of changes in HbA1c (between-group difference: -0.06%, 95% confidence interval [CI]: -0.19, 0.06) and fasting plasma glucose (between-group difference: -3.49 mg/dl [-8.08;1.10]). An increase in urine glucose-creatinine ratio was significantly greater in the enavogliflozin group than in the dapagliflozin group (60.2 g/g versus 43.5 g/g, P < 0.0001). The incidence of treatment-emergent adverse events was similar between the groups (21.64% versus 23.53%). CONCLUSIONS: Enavogliflozin, added to metformin plus gemigliptin, was well tolerated and as effective as dapagliflozin in the treatment of patients with T2DM.

Efficacy and Safety of Enavogliflozin versus Dapagliflozin as Add-on to Metformin in Patients with Type 2 Diabetes Mellitus: A 24-Week, Double-Blind, Randomized Trial.

BACKGRUOUND: Enavogliflozin is a novel sodium-glucose cotransporter-2 inhibitor currently under clinical development. This study evaluated the efficacy and safety of enavogliflozin as an add-on to metformin in Korean patients with type 2 diabetes mellitus (T2DM) against dapagliflozin. METHODS: In this multicenter, double-blind, randomized, phase 3 study, 200 patients were randomized to receive enavogliflozin 0.3 mg/day (n=101) or dapagliflozin 10 mg/day (n=99) in addition to ongoing metformin therapy for 24 weeks. The primary objective of the study was to prove the non-inferiority of enavogliflozin to dapagliflozin in glycosylated hemoglobin (HbA1c) change at week 24 (non-inferiority margin of 0.35%) (Clinical trial registration number: NCT04634500). RESULTS: Adjusted mean change of HbA1c at week 24 was -0.80% with enavogliflozin and -0.75% with dapagliflozin (difference, -0.04%; 95% confidence interval, -0.21% to 0.12%). Percentages of patients achieving HbA1c <7.0% were 61% and 62%, respectively. Adjusted mean change of fasting plasma glucose at week 24 was -32.53 and -29.14 mg/dL. An increase in urine glucose-creatinine ratio (60.48 vs. 44.94, P<0.0001) and decrease in homeostasis model assessment of insulin resistance (-1.85 vs. -1.31, P=0.0041) were significantly greater with enavogliflozin than dapagliflozin at week 24. Beneficial effects of enavogliflozin on body weight (-3.77 kg vs. -3.58 kg) and blood pressure (systolic/diastolic, -5.93/-5.41 mm Hg vs. -6.57/-4.26 mm Hg) were comparable with those of dapagliflozin, and both drugs were safe and well-tolerated. CONCLUSION: Enavogliflozin added to metformin significantly improved glycemic control in patients with T2DM and was non-inferior to dapagliflozin 10 mg, suggesting enavogliflozin as a viable treatment option for patients with inadequate glycemic control on metformin alone.

SLITRK2 variants associated with neurodevelopmental disorders impair excitatory synaptic function and cognition in mice.

SLITRK2 is a single-pass transmembrane protein expressed at postsynaptic neurons that regulates neurite outgrowth and excitatory synapse maintenance. In the present study, we report on rare variants (one nonsense and six missense variants) in SLITRK2 on the X chromosome identified by exome sequencing in individuals with neurodevelopmental disorders. Functional studies showed that some variants displayed impaired membrane transport and impaired excitatory synapse-promoting effects. Strikingly, these variations abolished the ability of SLITRK2 wild-type to reduce the levels of the receptor tyrosine kinase TrkB in neurons. Moreover, Slitrk2 conditional knockout mice exhibited impaired long-term memory and abnormal gait, recapitulating a subset of clinical features of patients with SLITRK2 variants. Furthermore, impaired excitatory synapse maintenance induced by hippocampal CA1-specific cKO of Slitrk2 caused abnormalities in spatial reference memory. Collectively, these data suggest that SLITRK2 is involved in X-linked neurodevelopmental disorders that are caused by perturbation of diverse facets of SLITRK2 function.

Efficacy and Safety of a New Sustained-release Pregabalin Formulation Compared With Immediate-release Pregabalin in Patients With Peripheral Neuropathic Pain: A Randomized Noninferiority Phase 3 Trial.

OBJECTIVE: This study investigated whether a new sustained-release (SR) pregabalin formulation is noninferior to immediate-release (IR) pregabalin in alleviating peripheral neuropathic pain in Korean patients. MATERIALS AND METHODS: This was a randomized, double-blind, active-controlled phase 3 study of patients with diabetic peripheral neuropathy or postherpetic neuralgia from 41 sites in South Korea in 2017-2018. Eligible patients were randomized (1:1) to receive once-daily SR pregabalin or twice-daily IR pregabalin (150 to 600 mg/d) in a double-dummy manner for 12 weeks according to a stratified permuted block randomization scheme. The primary endpoint was the Daily Pain Rating Scale score at the end of treatment, averaged from the last 7 available scores. RESULTS: A total of 319 of 371 (86.0%) randomized patients completed the 12-week treatment (SR pregabalin: n=154; IR pregabalin: n=165; per-protocol set: n=296). The least square mean difference between both groups for the primary endpoint was 0.06 (SE 0.19); (95% confidence interval -0.31 to 0.42), with the lower limit of the confidence interval above the pre-specified margin (-0.78; Pnoninferiority<0.0001). Drug-related treatment-emergent adverse events (TEAEs) were comparable between both groups. The incidence of drug-related TEAEs leading to treatment discontinuation was low (SR pregabalin: 2.7%; IR pregabalin: 1.1%). No serious drug-related TEAEs or deaths occurred. DISCUSSION: The results demonstrate that the new once-daily SR pregabalin formulation is noninferior to twice-daily IR pregabalin in reducing peripheral neuropathic pain and is well tolerated in Korean patients with diabetic peripheral neuropathy or postherpetic neuralgia after 12 weeks of treatment.

SALM4 negatively regulates NMDA receptor function and fear memory consolidation.

Many synaptic adhesion molecules positively regulate synapse development and function, but relatively little is known about negative regulation. SALM4/Lrfn3 (synaptic adhesion-like molecule 4/leucine rich repeat and fibronectin type III domain containing 3) inhibits synapse development by suppressing other SALM family proteins, but whether SALM4 also inhibits synaptic function and specific behaviors remains unclear. Here we show that SALM4-knockout (Lrfn3-/-) male mice display enhanced contextual fear memory consolidation (7-day post-training) but not acquisition or 1-day retention, and exhibit normal cued fear, spatial, and object-recognition memory. The Lrfn3-/- hippocampus show increased currents of GluN2B-containing N-methyl-D-aspartate (NMDA) receptors (GluN2B-NMDARs), but not α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors (AMPARs), which requires the presynaptic receptor tyrosine phosphatase PTPσ. Chronic treatment of Lrfn3-/- mice with fluoxetine, a selective serotonin reuptake inhibitor used to treat excessive fear memory that directly inhibits GluN2B-NMDARs, normalizes NMDAR function and contextual fear memory consolidation in Lrfn3-/- mice, although the GluN2B-specific NMDAR antagonist ifenprodil was not sufficient to reverse the enhanced fear memory consolidation. These results suggest that SALM4 suppresses excessive GluN2B-NMDAR (not AMPAR) function and fear memory consolidation (not acquisition).

Vibration Perception Threshold and Related Factors for Balance Assessment in Patients with Type 2 Diabetes Mellitus.

Diabetic peripheral neuropathy (DPN) is a common complication of type 2 diabetes mellitus (DM). DPN causes a decrease in proprioception, which could reduce balance ability. We investigated the association of impaired vibration sense, based on vibration perception threshold (VPT), with assessments of balance and other factors affecting balance impairment and fear of falling in patients with type 2 DM. Sixty-three patients with DM aged >50 years were categorized as having normal vibration sense (NVS; n = 34) or impaired vibration sense (IVS; n = 29) according to a VPT value of 8.9 µm. The following parameters were evaluated for all patients: postural steadiness through the fall index using posturography, functional balance through the Berg Balance Scale (BBS), the Timed Up and Go test (TUG), and fear of falling through the Falls Efficacy Scale-International (FES-I). The IVS group showed a significantly greater balance impairment in fall index, BBS, and TUG, as well as greater fear of falling on the FES-I than the NVS group. The linear regression analysis showed that the fall index was associated only with the VPT, whereas BBS, TUG, and FES-I were associated with the VPT, age, and/or lower extremity muscle strength. VPT, age, and/or muscle strength were identified as predictors of balance and fear of falling in patients with type 2 DM. Therefore, along with age and lower extremity strength, the VPT can be useful for balance assessment in patients with type 2 DM.

Differentially altered social dominance- and cooperative-like behaviors in Shank2- and Shank3-mutant mice.

BACKGROUND: Recent progress in genomics has contributed to the identification of a large number of autism spectrum disorder (ASD) risk genes, many of which encode synaptic proteins. Our understanding of ASDs has advanced rapidly, partly owing to the development of numerous animal models. Extensive characterizations using a variety of behavioral batteries that analyze social behaviors have shown that a subset of engineered mice that model mutations in genes encoding Shanks, a family of excitatory postsynaptic scaffolding proteins, exhibit autism-like behaviors. Although these behavioral assays have been useful in identifying deficits in simple social behaviors, alterations in complex social behaviors remain largely untested. METHODS: Two syndromic ASD mouse models-Shank2 constitutive knockout [KO] mice and Shank3 constitutive KO mice-were examined for alterations in social dominance and social cooperative behaviors using tube tests and automated cooperation tests. Upon naïve and salient behavioral experience, expression levels of c-Fos were analyzed as a proxy for neural activity across diverse brain areas, including the medial prefrontal cortex (mPFC) and a number of subcortical structures. FINDINGS: As previously reported, Shank2 KO mice showed deficits in sociability, with intact social recognition memory, whereas Shank3 KO mice displayed no overt phenotypes. Strikingly, the two Shank KO mouse models exhibited diametrically opposed alterations in social dominance and cooperative behaviors. After a specific social behavioral experience, Shank mutant mice exhibited distinct changes in number of c-Fos+ neurons in the number of cortical and subcortical brain regions. CONCLUSIONS: Our results underscore the heterogeneity of social behavioral alterations in different ASD mouse models and highlight the utility of testing complex social behaviors in validating neurodevelopmental and neuropsychiatric disorder models. In addition, neural activities at distinct brain regions are likely collectively involved in eliciting complex social behaviors, which are differentially altered in ASD mouse models.

Protocol for Quantitative Analysis of Synaptic Vesicle Clustering in Axons of Cultured Neurons.

Clustering of synaptic vesicles along the neuronal axons is a critical mechanism underpinning proper synaptic transmission. Here, we provide a detailed protocol for analyzing the distribution of synaptic vesicles in presynaptic boutons of cultured neurons. The protocol covers preparation of cultured neurons, expression of synaptic vesicle-enriched proteins, and quantification procedures. Utilizing neurons from postnatal transgenic mice, this method can be applied to investigate the roles of synaptic genes in regulating vesicle dynamics at synaptic sites. For complete details on the use and execution of this protocol, please refer to Han et al. (2020a).

LAR-RPTPs Directly Interact with Neurexins to Coordinate Bidirectional Assembly of Molecular Machineries.

Neurexins (Nrxns) and LAR-RPTPs (leukocyte common antigen-related protein tyrosine phosphatases) are presynaptic adhesion proteins responsible for organizing presynaptic machineries through interactions with nonoverlapping extracellular ligands. Here, we report that two members of the LAR-RPTP family, PTPσ and PTPδ, are required for the presynaptogenic activity of Nrxns. Intriguingly, Nrxn1 and PTPσ require distinct sets of intracellular proteins for the assembly of specific presynaptic terminals. In addition, Nrxn1α showed robust heparan sulfate (HS)-dependent, high-affinity interactions with Ig domains of PTPσ that were regulated by the splicing status of PTPσ. Furthermore, Nrxn1α WT, but not a Nrxn1α mutant lacking HS moieties (Nrxn1α ΔHS), inhibited postsynapse-inducing activity of PTPσ at excitatory, but not inhibitory, synapses. Similarly, cis expression of Nrxn1α WT, but not Nrxn1α ΔHS, suppressed the PTPσ-mediated maintenance of excitatory postsynaptic specializations in mouse cultured hippocampal neurons. Lastly, genetics analyses using male or female Drosophila Dlar and Dnrx mutant larvae identified epistatic interactions that control synapse formation and synaptic transmission at neuromuscular junctions. Our results suggest a novel synaptogenesis model whereby different presynaptic adhesion molecules combine with distinct regulatory codes to orchestrate specific synaptic adhesion pathways.SIGNIFICANCE STATEMENT We provide evidence supporting the physical interactions of neurexins with leukocyte common-antigen related receptor tyrosine phosphatases (LAR-RPTPs). The availability of heparan sulfates and alternative splicing of LAR-RPTPs regulate the binding affinity of these interactions. A set of intracellular presynaptic proteins is involved in common for Nrxn- and LAR-RPTP-mediated presynaptic assembly. PTPσ triggers glutamatergic and GABAergic postsynaptic differentiation in an alternative splicing-dependent manner, whereas Nrxn1α induces GABAergic postsynaptic differentiation in an alternative splicing-independent manner. Strikingly, Nrxn1α inhibits the glutamatergic postsynapse-inducing activity of PTPσ, suggesting that PTPσ and Nrxn1α might control recruitment of a different pool of postsynaptic machinery. Drosophila orthologs of Nrxns and LAR-RPTPs mediate epistatic interactions in controlling synapse structure and strength at neuromuscular junctions, underscoring the physiological significance in vivo.