Structural insights into adhesion GPCR ADGRL3 activation and Gq, Gs, Gi, and G12 coupling.

Adhesion G-protein-coupled receptors (aGPCRs) play key roles in a diversity of physiologies. A hallmark of aGPCR activation is the removal of the inhibitory GAIN domain and the dipping of the cleaved stalk peptide into the ligand-binding pocket of receptors; however, the detailed mechanism remains obscure. Here, we present cryoelectron microscopy (cryo-EM) structures of ADGRL3 in complex with Gq, Gs, Gi, and G12. The structures reveal unique ligand-engaging mode, distinctive activation conformation, and key mechanisms of aGPCR activation. The structures also reveal the uncharted structural information of GPCR/G12 coupling. A comparison of Gq, Gs, Gi, and G12 engagements with ADGRL3 reveals the key determinant of G-protein coupling on the far end of αH5 of Gα. A detailed analysis of the engagements allows us to design mutations that specifically enhance one pathway over others. Taken together, our study lays the groundwork for understanding aGPCR activation and G-protein-coupling selectivity.

Structural basis of sphingosine-1-phosphate receptor 1 activation and biased agonism.

Sphingosine-1-phosphate receptor 1 (S1PR1) is a master regulator of lymphocyte egress from the lymph node and an established drug target for multiple sclerosis (MS). Mechanistically, therapeutic S1PR1 modulators activate the receptor yet induce sustained internalization through a potent association with ß-arrestin. However, a structural basis of biased agonism remains elusive. Here, we report the cryo-electron microscopy (cryo-EM) structures of Gi-bound S1PR1 in complex with S1P, fingolimod-phosphate (FTY720-P) and siponimod (BAF312). In combination with functional assays and molecular dynamics (MD) studies, we reveal that the ß-arrestin-biased ligands direct a distinct activation path in S1PR1 through the extensive interplay between the PIF and the NPxxY motifs. Specifically, the intermediate flipping of W2696.48 and the retained interaction between F2656.44 and N3077.49 are the key features of the ß-arrestin bias. We further identify ligand-receptor interactions accounting for the S1PR subtype specificity of BAF312. These structural insights provide a rational basis for designing novel signaling-biased S1PR modulators.

Attention network training promotes selective attention of children with low socioeconomic status.

The objectives of this study were to evaluate the difference of selective attention efficiency between children with low and high socioeconomic status (SES) and the promotional effect of attention network training (an attention network test was used as the training task) on selective attention in children with the low SES. A total of 139 10- to 12-year-old children participated in two experiments (71 in Experiment 1 and 68 in Experiment 2). The results suggest that selective attention and switch ability of children with high SES are better than those of children with low SES. After attention network training, selective attention, switch ability, and working memory of low-SES children improved significantly. The findings provide evidence that attention network training could enhance selective attention in low-SES children and that the beneficial training effect could also transfer to switch ability and working memory. The research may provide a promising method to compensate cognitive delay of low-SES children.

The role of experience in parenting beliefs of British and Italian women during pregnancy.

To understand the role of experience in parenting beliefs about caring for infants, we examined the parenting beliefs of pregnant women who were expecting their first child with those of pregnant women who already had at least one other child. A culturally diverse sample of 550 British and Italian women completed self-report measures evaluating their beliefs about the value of attunement and structure in caregiving, parenting self-efficacy, and home chaos. Psychometric evaluation confirmed the two-factor structure of the Baby Care Questionnaire (BCQ) for measuring attunement and structure but did not support configural invariance across the different samples. Beliefs about attunement and structure were related to parenting experience: pregnant women who already had at least one other child reported stronger beliefs in attunement, whereas pregnant women expecting their first child reported stronger beliefs in structure. Regression analyses revealed that the associations between parenting beliefs and experience remained when controlling for country, age, and education. Despite the limitations imposed by the lack of configural invariance, this cross-sectional, cross-cultural study constitutes an important first step in examining the relations between parenting experience and parenting beliefs during pregnancy.

Para comprender el papel de la experiencia en las creencias de crianza sobre el cuidado de los infantes, examinamos las creencias de crianza de mujeres embarazadas que esperaban su primer niño con aquellas de mujeres embarazadas que ya tenían por lo menos otro niño. Un grupo muestra culturalmente diverso de quinientas cincuenta mujeres británicas e italianas completó medidas auto reportadas de evaluación de sus creencias acerca del valor de la coordinación armónica y la estructura en cuanto al cuidado, la auto efectividad de la crianza, así como el caos en casa. La evaluación sicométrica confirmó la estructura de dos factores del Cuestionario de Cuidado del Bebé (BCQ: Winstanley y Gattis, 2013) para medir la coordinación armónica y la estructura, pero no apoyó la invariabilidad configuracional a través de los diferentes grupos muestra. Las creencias acerca de la coordinación armónica y la estructura se relacionaron con la experiencia de la crianza: las mujeres embarazadas que ya tenían por lo menos otro niño reportaron creencias más fuertes en cuanto a la coordinación armónica, mientras que las mujeres embarazadas que esperaban su primer niño reportaron creencias más fuertes en cuanto a la estructura. Los análisis de regresión revelaron que las asociaciones entre las creencias de crianza y la experiencia se mantenían siendo las mismas cuando se usaron los controles referentes a país, edad y educación. A pesar de las limitaciones impuestas por la falta de la invariabilidad configuracional, este estudio interseccional constituye un importante paso en el examen de las relaciones entre la experiencia de crianza y las creencias sobre la crianza durante el embarazo.

Afin de comprendre le rôle de l'expérience dans les croyances de parentalité sur la manière de prendre soin des bébés, nous avons examiné les croyances de parentalité de femmes enceintes qui attendaient leur premier enfant avec celles de femmes enceintes ayant déjà eu au moins un enfant. Un échantillon culturellement divers de cinq cent cinquante femmes britanniques et italiennes ont rempli des mesures auto-rapportées évaluant leurs croyances concernant la valeur de l'harmonisation et de la structure dans les soins à l'enfant, l'auto-efficacité de parentalité, et le chaos à domicile. L'évaluation psychométrique a confirmé la structure à deux facteurs du Questionnaire du Soin au Bébé (abrégé BCQ en anglais; Winstanley & Gattis, 2013) pour la mesure de l'harmonisation et de la structure mais n'a pas soutenu l'invariance de configuration au travers des différents échantillons. Les croyances sur l'harmonisation et la structure étaient liées à l'expérience de parentalité: les femmes enceintes qui avaient déjà eu un enfant ont fait état de croyances plus fortes dans l'harmonisation, alors que les femmes enceintes attendant leur premier enfant ont fait état de croyances plus fortes dans la structure. Des analyses de régression ont révélé que les liens entre les croyances de parentalité et l'expérience demeuraient quand on contrôlait pour le pays, l'âge et l'éducation. En dépit des limitations imposées par le manque d'invariance de configuration, cette étude transversale et multiculturelle constitue une étape importante dans l'examen des relations entre l'expérience de parentalité et les croyances de parentalité durant la grossesse.

[Two new polypeptides from extract of deer bone extract].

Two new polypeptides were isolated and purified from the extract of deer bone (constitutive part of Cucumis and Cervus polypeptide injection) by various column chromatography including C4 300Å and Sephadex G-50, as well as semipreparative HPLC. Their N-terminal amino acid sequences were identified by De Novo sequencing on the basis of MALDI-TOF-MS data and Explorer™ software. The N-terminal amino acid sequences of polypeptides were identified as NH2-Gly-Pro-Val-Gly-Pro-Thr-Gly-Pro-Val-Gly-Ala-Ala-Gly-Pro-Ser-Gly-Pro-Asp (Mei18 peptide, 1) and NH2-Ala-Gly-Pro-Ala-Gly-Pro-Leu-Gly-Pro-Leu-Gly-Pro-Leu-Gly-Pro-Leu-Gly-Pro-Pro-Asp-Ser-Try-Asp (Mei23 peptide, 2), respectively. Mei18 and Mei 23 peptides are new polypeptides.

Neuroprotective Effects of Pycnogenol Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Injury in Primary Rat Astrocytes via NF-κB and ERK1/2 MAPK Pathways.

BACKGROUNDS/AIMS: Pycnogenol (PYC) is a patented mix of bioflavonoids with potent anti-oxidant and anti-inflammatory properties. In this study, we investigated the effects of PYC on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in primary rat astrocytes. METHODS: The primary rat astrocytes were randomly divided into 6 groups, blank control, OGD/R, OGD/R+PYC (10, 20, 40, and 60 µg/mL). The cell activity were detected by MTT and LDH assays, then the levels of oxidant products [malondialdehyde (MDA) and reactive oxygen species (ROS)] , antioxidants [superoxide dismutase (SOD)], mitochondrial membrane potential (MMP) and inflammatory cytokines were detected. In addition, the expression levels of apoptosis-related proteins (Bax, Bcl-2 and Cleaved caspase 3), proinflammatory factors (NF-κB p65), and p-ERK1/2 were measured by Western blot analysis. RESULTS: The results showed that PYC incubation dose-dependently attenuated cell viability loss, LDH leakage, oxidative stress, inflammatory cytokines accumulation and cell apoptosis caused by OGD/R. Furthermore, PYC pretreatment dose-dependently suppressed OGD/R-induced NF-κB p65 nuclear translocation, NF-κB activity and ERK1/2 phosphorylation. Similarly to PYC, NF-κB inhibitor PDTC and ERK1/2 inhibitor PD098059 dramatically inhibited OGD/R-induced NF-κB activation, ERK1/2 phosphorylation, and ROS production, as well as TNF-α secretion. CONCLUSIONS: These findings revealed that PYC has neuroprotective effects against OGD/R-induced injury via NF-κB and ERK1/2 pathways in primary rat astrocytes.

A facile method to in situ fabricate three dimensional gold nanoparticle micropatterns in a cell-resistant hydrogel.

A facile method for in situ fabrication of three-dimensional gold nanoparticle micropatterns in a cell-resistant polyethylene glycol hydrogel has been developed by combining photochemical synthesis of gold nanoparticles with photolithography technology. The gold nanoparticle micropatterns were further bio-modified with cell integrated polypeptide NcysBRGD based on a gold-thiol bond to improve cell behaviors. Primary cell tests showed that NcysBRGD can enhance cell adhesion very well on the surface of gold nanoparticle micropatterns.

An engineered coiled-coil polypeptide assembled onto quantum dots for targeted cell imaging.

Quantum dot (QD)-polypeptide probes have been developed through the specific metal-affinity interaction between polypeptides appended with N-terminal polyhistidine sequences and CdSe/ZnS core-shell QDs. The size and charge of a QD-polypeptide can be tuned by using different coiled-coil polypeptides. Compared to glutathione-capped QDs (QD-GSH), QD-polypeptide probes showed an approximately two- to three-fold luminescence increase, and the luminescence increase was not obviously related to the charge of the polypeptide. QD-polypeptide probes with different charge have a great effect on nonspecific cellular uptake. QD-polypeptide probes with negative charge exhibited lower nonspecific cellular uptake in comparison to the QD-GSH, while positively charged QD-polypeptide probes presented higher cellular uptake than the QD-GSH. A targeted QD-ARGD probe can obviously increase targeted cellular uptake in α v ß 3 overexpressing HeLa cells compared to QD-A. In addition, QD-polypeptide probes showed lower in vitro cytotoxicity compared to the original QDs. These results demonstrate that these QD-polypeptide probes with high specific cellular uptake, high fluorescence intensity and low background noise are expected to have great potential applications in targeted cell imaging.

Sex-biased single-cell genetic landscape in mice with autism spectrum disorder.

Autistic spectrum disorder (ASD) is a male-biased, heterogeneous neurodevelopmental disorder that affects approximately 1%-2% of the population. Prenatal exposure to valproic acid (VPA) is a recognized risk factor for ASD, but the cellular and molecular basis of VPA-induced ASD at the single-cell resolution is unclear. Here, we aim to compare the cellular and molecular differences in the hippocampus between male and female prenatal mice with ASD at the single-cell transcriptomic level. The transcriptomes of more than 45,000 cells are assigned to 12 major cell types, including neurons, glial cells, vascular cells, and immune cells. Cell type-specific genes with altered expression after prenatal VPA exposure are analyzed, and the largest number of differentially expressed genes (DEGs) are found in neurons, choroid plexus epithelial cells, and microglia. In microglia, several pathways related to inflammation are found in both males and females, including the tumor necrosis factor (TNF), nuclear factor kappa B (NF-κB), toll-like receptor (TLR), and mitogen-activated protein kinase (MAPK) signaling pathways, which are important for the induction of autistic-like behavior. Additionally, we note that several X-linked genes, including Bex1, Bex3, and Gria3, were among the male-specific DEGs of neurons. This pioneering study describes the landscape of the transcriptome in the hippocampus of autistic mice. The elucidation of sexual differences could provide innovative strategies for the prevention and treatment of ASD.

Effects of perspective taking on attention bias to body-related information among junior high school students with body image disturbance.

Using lexical judgment tasks, the present study explored whether perspective taking affected attention bias to body-related information among junior high school students with body image disturbance. Experiment 1 examined the junior high school students' attention bias to body schema-related words; the results showed the body image disturbance group responded significantly more quickly to negative body schema-related words than positive words, whereas the control group did not show a significant difference between positive and negative words. In Experiment 2, participants were asked to judge whether the positive or negative body schema-related words were suitable to describe themselves, when adopting their own perspective or that of another person. The results showed that reaction times to negative words were significantly shorter than to positive words when adopting a self-perspective. When taking another's perspective, there was no significant difference of reaction time between positive and negative words. This result demonstrated that perspective taking reduced attention bias to negative body schema-related information among junior high school students with body image disturbance. The present research suggests that guiding adolescents to view themselves from different perspectives can help them form a more accurate and objective body image.

Structural basis of ligand recognition and design of antihistamines targeting histamine H4 receptor.

The histamine H4 receptor (H4R) plays key role in immune cell function and is a highly valued target for treating allergic and inflammatory diseases. However, structural information of H4R remains elusive. Here, we report four cryo-EM structures of H4R/Gi complexes, with either histamine or synthetic agonists clobenpropit, VUF6884 and clozapine bound. Combined with mutagenesis, ligand binding and functional assays, the structural data reveal a distinct ligand binding mode where D943.32 and a π-π network determine the orientation of the positively charged group of ligands, while E1825.46, located at the opposite end of the ligand binding pocket, plays a key role in regulating receptor activity. The structural insight into H4R ligand binding allows us to identify mutants at E1825.46 for which the agonist clobenpropit acts as an inverse agonist and to correctly predict inverse agonism of a closely related analog with nanomolar potency. Together with the findings regarding receptor activation and Gi engagement, we establish a framework for understanding H4R signaling and provide a rational basis for designing novel antihistamines targeting H4R.

Identification of oleic acid as an endogenous ligand of GPR3.

Although GPR3 plays pivotal roles in both the nervous system and metabolic processes, such as cold-induced thermogenesis, its endogenous ligand remains elusive. Here, by combining structural approach (including cryo-electron microscopy), mass spectrometry analysis, and functional studies, we identify oleic acid (OA) as an endogenous ligand of GPR3. Our study reveals a hydrophobic tunnel within GPR3 that connects the extracellular side of the receptor to the middle of plasma membrane, enabling fatty acids to readily engage the receptor. Functional studies demonstrate that OA triggers downstream Gs signaling, whereas lysophospholipids fail to activate the receptor. Moreover, our research reveals that cold stimulation induces the secretion of OA in mice, subsequently activating Gs/cAMP/PKA signaling in brown adipose tissue. Notably, brown adipose tissues from Gpr3 knockout mice do not respond to OA during cold stimulation, reinforcing the significance of GPR3 in this process. Finally, we propose a "born to be activated and cold to enhance" model for GPR3 activation. Our study provides a starting framework for the understanding of GPR3 signaling in cold-stimulated thermogenesis.

PM2.5 promotes apoptosis of alveolar epithelial cells via targeting ROS/p38 signaling pathway and thus leads to emphysema in mice.

BACKGROUND: The aim of this study was to uncover the ability of PM2.5 exposure to induce apoptosis in alveolar epithelial cells by stimulating excessive production of reactive oxygen species (ROS), thus activating p38 to result in emphysema in mice. METHODS: Male BALB/c mice with 6-8-week-old were exposed to 200 TPM mg/L PM2.5 for 12 weeks. Lung tissues of mice were harvested after sacrifice. Hematoxylin and eosin staining was conducted for observing alveolar structure change. Protein levels of p-p38 and p38, as well as ROS level in mouse liver tissues were determined. A549 cells were exposed to different doses of PM2.5, followed by ROS detection, protein level detection of p-p38 and p38, and apoptosis determination. After transfection of si-p38, protein level of clv-caspase3 and apoptotic rate in PM2.5-exposed A549 cells were assessed. RESULTS: After 12-week exposure to PM2.5, enlarged alveolar space, elevated ROS level in lung tissues and activated p38 were observed in mice. In PM2.5-exposed A549 cells, ROS level, p-p38 expression and apoptotic rate were dose-dependently enhanced. The antioxidant NAC reversed the above changes in PM2.5-exposed A549 cells. Silence of p38 reversed the enhanced clv-claspase3 level and apoptotic rate in PM2.5-exposed A549 cells. CONCLUSIONS: PM2.5 exposure elevates ROS level in lung tissues, and activates p38, thus leading to apoptosis of alveolar epithelial cells. PM2.5 finally results in the development of emphysema in mice.

Structural basis of CD97 activation and G-protein coupling.

CD97 (ADGRE5) is an adhesion G protein-coupled receptor (aGPCR) which plays crucial roles in immune system and cancer. However, the mechanism of CD97 activation and the determinant of G13 coupling selectivity remain unknown. Here, we present the cryo-electron microscopy structures of human CD97 in complex with G13, Gq, and Gs. Our structures reveal the stalk peptide recognition mode of CD97, adding missing information of the current tethered-peptide activation model of aGPCRs. For instance, a revised "FXφφφ" motif and a framework of conserved aromatic residues in the ligand-binding pocket. Importantly, structural comparisons of G13, Gq, and Gs engagements of CD97 reveal key determinants of G13 coupling selectivity, where a deep insertion of the α helix 5 and a closer contact with the transmembrane helix 6, 5, and 3 dictate coupling preferences. Taken together, our structural study of CD97 provides a framework for understanding CD97 signaling and the G13 coupling selectivity.

Variations in the soil micro-food web structure and its relationship with soil C and N mineralization during secondary succession of subalpine forests.

The soil micro-food web is an important network of belowground trophic relationships and it participates directly and indirectly in soil ecological processes. In recent decades, the roles of the soil micro-food web in regulating ecosystem functions in grasslands and agroecosystems have received much attention. However, the variations in the soil micro-food web structure and its relationship with ecosystem functions during forest secondary succession remain unclear. In this study, we investigated how forest secondary succession affected the soil micro-food web (including soil microbes and nematodes) and soil carbon and nitrogen mineralization across a successional sequence of "grasslands - shrublands - broadleaf forests - coniferous forests" in a subalpine region of southwestern China. With forest successional development, the total soil microbial biomass and the biomass of each microbial group generally increased. The significant influences of forest succession on soil nematodes were mainly reflected in several trophic groups with high colonizer-persister values (particularly bacterivore3, herbivore5 and omnivore-predator5) that are sensitive to environmental disturbance. The increases in the connectance and nematode genus richness, diversity, and maturity index indicated an increasingly stable and complex soil micro-food web with forest succession, which was closely related to soil nutrients, particularly the soil carbon contents. Additionally, we found that the soil carbon and nitrogen mineralization rates also exhibited generally increasing trends during forest succession, which had significant positive correlations with the soil micro-food web composition and structure. The path analysis results indicated that the variances in ecosystem functions induced by forest succession were significantly determined by soil nutrients and soil microbial and nematode communities. Overall, these results suggested that forest succession enriched and stabilized the soil micro-food web and promoted ecosystem functions via the increase in soil nutrients, and the soil micro-food web played an important role in regulating ecosystem functions during forest succession.

Structural basis of lysophosphatidylserine receptor GPR174 ligand recognition and activation.

Lysophosphatidylserine (LysoPS) is a lipid mediator that induces multiple cellular responses through binding to GPR174. Here, we present the cryo-electron microscopy (cryo-EM) structure of LysoPS-bound human GPR174 in complex with Gs protein. The structure reveals a ligand recognition mode, including the negatively charged head group of LysoPS forms extensive polar interactions with surrounding key residues of the ligand binding pocket, and the L-serine moiety buries deeply into a positive charged cavity in the pocket. In addition, the structure unveils a partially open pocket on transmembrane domain helix (TM) 4 and 5 for a lateral entry of ligand. Finally, the structure reveals a Gs engaging mode featured by a deep insertion of a helix 5 (αH5) and extensive polar interactions between receptor and αH5. Taken together, the information revealed by our structural study provides a framework for understanding LysoPS signaling and a rational basis for designing LysoPS receptor-targeting drugs.

Targeting DNA polymerase ß elicits synthetic lethality with mismatch repair deficiency in acute lymphoblastic leukemia.

Mismatch repair (MMR) deficiency has been linked to thiopurine resistance and hypermutation in relapsed acute lymphoblastic leukemia (ALL). However, the repair mechanism of thiopurine-induced DNA damage in the absence of MMR remains unclear. Here, we provide evidence that DNA polymerase ß (POLB) of base excision repair (BER) pathway plays a critical role in the survival and thiopurine resistance of MMR-deficient ALL cells. In these aggressive resistant ALL cells, POLB depletion and its inhibitor oleanolic acid (OA) treatment result in synthetic lethality with MMR deficiency through increased cellular apurinic/apyrimidinic (AP) sites, DNA strand breaks and apoptosis. POLB depletion increases thiopurine sensitivities of resistant cells, and OA synergizes with thiopurine to kill these cells in ALL cell lines, patient-derived xenograft (PDX) cells and xenograft mouse models. Our findings suggest BER and POLB's roles in the process of repairing thiopurine-induced DNA damage in MMR-deficient ALL cells, and implicate their potentials as therapeutic targets against aggressive ALL progression.

Analysis of the expression levels of chemerin, ox-LDL, MMP-9, and PAPP-A in ICVD patients and their relationship with the severity of neurological impairment.

OBJECTIVE: The study aimed to analyze the relationship between expression levels of chemerin, oxidized low density lipoprotein (ox-LDL), matrix metalloproteinase 9 (MMP-9) and pregnancy associated plasma protein A (PAPP-A) in ischemic cerebrovascular disease (ICVD) patients and the relationship between the mentioned indicators and the degree of neurological impairment. METHODS: From January 2020 to February 2021, a total of 328 cases of ICVD patients were admitted to our hospital, and 240 cases of healthy people (control group) were prospectively recruited into this study. The 328 patients were divided into 2 ischemic subtypes, with 233 cases as acute cerebral infarction (ACI) and 95 cases as transient ischemic attack (TIA). Laboratory tests were compared among the groups. Spearman rank correlation was used to analyze the correlation between chemerin, ox-LDL, MMP-9, PAPP-A levels and neurological deficit. Unconditional logisitic regression was used to analyze the risk factors for neurological deficits. RESULTS: The high density lipoprotein cholesterol (HDL-C), fasting plasma glucose (FPG), chemerin, ox-LDL, MMP-9, and PPAP-A levels in the ACI group were significantly higher than those in the TIA group and control group (p < 0.05, respectively), while the levels of the mentioned indicators in the TIA group were significantly higher than those in control group (p < 0.05, respectively). The levels of the given indicators decreased successively in the severe, moderate, and mild neurological deficits population and control group, with statistical difference. Spearman rank correlation analysis showed that chemerin, ox-LDL, MMP-9, and PPAP-A levels were positively correlated with the degree of neurological deficit in ICVD patients. Unconditional logistic regression analysis showed that chemerin, ox-LDL, MMP-9, and PPAP-A were the independent risk factors for neurological deficit in patients with ICVD. CONCLUSION: LDL-C, FPG, chemerin, ox-LDL, MMP-9, and PPAP-A were highly expressed in ACI and neurological deficit patients. Chemerin, ox-LDL, MMP-9, and PPAP-A may be the independent risk factors for neurological deficit in patients with ICVD.

Associations of parenting daily hassles with parents' mental health during the COVID-19 school closure.

RATIONALE: Parenting is a demanding task associated with parents' mental health, which is likely exacerbated by the COVID-19 pandemic lockdown. The present study investigated daily parenting hassles and their effects on parents' mental health during this period. METHODS: A total of 7314 parents with children aged 3-14 years old completed a sociodemographic questionnaire and reported on their perceived daily parenting hassles, mental health, family support, and co-parenting during the COVID-19 school closure. RESULTS: Most parents (73.4%) showed different degrees of daily hassles, and a relatively higher prevalence of depression (18.7%), anxiety (22.4%), and stress (12.1%) were found. Motherhood, parents' younger ages, lower education parents, job loss, and having younger children, boys, and multiple children were associated with elevated daily parenting hassles and mental health issues. Importantly, daily parenting hassles were uniquely associated with mental health problems after controlling for various sociodemographic characteristics, family support, and co-parenting. Furthermore, family support and co-parenting can attenuate daily parenting hassles, which, in turn, protect parents' mental health. CONCLUSIONS: The findings of the present study underscore the critical need to consider daily parenting hassles and their effects on the mental health of parents during the COVID-19 lockdown. The present study also outlines potential factors (family support and co-parenting) that attenuate parents' daily parenting hassles and protect their mental health during the COVID-19 lockdown.