WDR1-regulated actin dynamics is required for outflow tract and right ventricle development

Deletion of PDK1 Caused Cardiac Malmorphogenesis and Heart Defects Due to Profound Protein Phosphorylation Changes Mediated by SHP2

Phosphoinositide-dependent protein kinase-1 (PDK1), a master kinase and involved in multiple signaling transduction, participates in regulating embryonic cardiac development and postnatal cardiac remodeling. Germline PDK1 knockout mice displayed no heart development; in this article, we deleted PDK1 in heart tissue with different cre to characterize the temporospatial features and find the relevance with congenital heart disease(CHD), furthermore to investigate the underlying mechanism. Knocking out PDK1 with Nkx2.5-cre, the heart showed prominent pulmonic stenosis. Ablated PDK1 with Mef2cSHF-cre, the second heart field (SHF) exhibited severe hypoplasia. And deleted PDK1 with αMHC-cre, the mice displayed dilated heart disease, protein analysis indicated PI3K and ERK were activated; meanwhile, PDK1-AKT-GSK3, and S6K-S6 were disrupted; phosphorylation level of Akt473, S6k421/424, and Gsk3α21 enhanced; however, Akt308, S6k389, and Gsk3β9 decreased. In mechanism investigation, we found SHP2 membrane localization and phosphorylation level of SHP2542 elevated, which suggested SHP2 likely mediated the disruption.

WDR62 variants contribute to congenital heart disease by inhibiting cardiomyocyte proliferation

Background

Congenital heart disease (CHD) is the most common birth defect and has high heritability. Although some susceptibility genes have been identified, the genetic basis underlying the majority of CHD cases is still undefined.

Methods

A total of 1320 unrelated CHD patients were enrolled in our study. Exome‐wide association analysis between 37 tetralogy of Fallot (TOF) patients and 208 Han Chinese controls from the 1000 Genomes Project was performed to identify the novel candidate gene WD repeat‐containing protein 62 (WDR62). WDR62 variants were searched in another expanded set of 200 TOF patients by Sanger sequencing. Rescue experiments in zebrafish were conducted to observe the effects of WDR62 variants. The roles of WDR62 in heart development were examined in mouse models with Wdr62 deficiency. WDR62 variants were investigated in an additional 1083 CHD patients with similar heart phenotypes to knockout mice by multiplex PCR‐targeting sequencing. The cellular phenotypes of WDR62 deficiency and variants were tested in cardiomyocytes, and the molecular mechanisms were preliminarily explored by RNA‐seq and co‐immunoprecipitation.

Results

Seven WDR62 coding variants were identified in the 237 TOF patients and all were indicated to be loss of function variants. A total of 25 coding and 22 non‐coding WDR62 variants were identified in 80 (6%) of the 1320 CHD cases sequenced, with a higher proportion of WDR62 variation (8%) found in the ventricular septal defect (VSD) cohort. WDR62 deficiency resulted in a series of heart defects affecting the outflow tract and right ventricle in mouse models, including VSD as the major abnormality. Cell cycle arrest and an increased number of cells with multipolar spindles that inhibited proliferation were observed in cardiomyocytes with variants or knockdown of WDR62. WDR62 deficiency weakened the association between WDR62 and the cell cycle‐regulated kinase AURKA on spindle poles, reduced the phosphorylation of AURKA, and decreased expression of target genes related to cell cycle and spindle assembly shared by WDR62 and AURKA.

Conclusions

WDR62 was identified as a novel susceptibility gene for CHD with high variant frequency. WDR62 was shown to participate in the cardiac development by affecting spindle assembly and cell cycle pathway in cardiomyocytes.

Proteomic Analysis of Exosomes during Cardiogenic Differentiation of Human Pluripotent Stem Cells

Efforts to direct the specification of human pluripotent stem cells (hPSCs) to therapeutically important somatic cell types have focused on identifying proper combinations of soluble cues. Yet, whether exosomes, which mediate intercellular communication, play a role in the differentiation remains unexplored. We took a first step toward addressing this question by subjecting hPSCs to stage-wise specification toward cardiomyocytes (CMs) in scalable stirred-suspension cultures and collecting exosomes. Samples underwent liquid chromatography (LC)/mass spectrometry (MS) and subsequent proteomic analysis revealed over 300 unique proteins from four differentiation stages including proteins such as PPP2CA, AFM, MYH9, MYH10, TRA2B, CTNNA1, EHD1, ACTC1, LDHB, and GPC4, which are linked to cardiogenic commitment. There was a significant correlation of the protein composition of exosomes with the hPSC line and stage of commitment. Differentiating hPSCs treated with exosomes from hPSC-derived CMs displayed improved efficiency of CM formation compared to cells without exogenously added vesicles. Collectively, these results demonstrate that exosomes from hPSCs induced along the CM lineage contain proteins linked to the specification process with modulating effects and open avenues for enhancing the biomanufacturing of stem cell products for cardiac diseases.

WD Repeat Domain 1 Deficiency Inhibits Neointima Formation in Mice Carotid Artery by Modulation of Smooth Muscle Cell Migration and Proliferation

The migration, dedifferentiation, and proliferation of vascular smooth muscle cells (VSMCs) are responsible for intimal hyperplasia, but the mechanism of this process has not been elucidated. WD repeat domain 1 (WDR1) promotes actin-depolymerizing factor (ADF)/cofilin-mediated depolymerization of actin filaments (F-actin). The role of WDR1 in neointima formation and progression is still unknown. A model of intimal thickening was constructed by ligating the left common carotid artery in Wdr1 deletion mice, and H&E staining showed that Wdr1 deficiency significantly inhibits neointima formation. We also report that STAT3 promotes the proliferation and migration of VSMCs by directly promoting WDR1 transcription. Mechanistically, we clarified that WDR1 promotes the proliferation and migration of VSMCs and neointima formation is regulated by the activation of the JAK2/STAT3/WDR1 axis.

Hippocampal Wdr1 Deficit Impairs Learning and Memory by Perturbing F-actin Depolymerization in Mice

WD repeat protein 1 (Wdr1), known as a cofactor of actin-depolymerizing factor (ADF)/cofilin, is conserved among eukaryotes, and it plays a critical role in the dynamic reorganization of the actin cytoskeleton. However, the function of Wdr1 in the central nervous system remains elusive. Using Wdr1 conditional knockout mice, we demonstrated that Wdr1 plays a significant role in regulating synaptic plasticity and memory. The knockout mice exhibited altered reversal spatial learning and fear responses. Moreover, the Wdr1 CKO mice showed significant abnormalities in spine morphology and synaptic function, including enhanced hippocampal long-term potentiation and impaired long-term depression. Furthermore, we observed that Wdr1 deficiency perturbed actin rearrangement through regulation of the ADF/cofilin activity. Taken together, these results indicate that Wdr1 in the hippocampal CA1 area plays a critical role in actin dynamics in associative learning and postsynaptic receptor availability.

Knockout of Wdr1 results in cardiac hypertrophy and impaired cardiac function in adult mouse heart

WDR1 is a major cofactor of the actin depolymerizing factor (ADF)/cofilin, accelerating ADF/cofilin-mediated actin disassembly. We had previously showed that WDR1-mediated actin dynamics is required for postnatal myocardial growth and adult myocardial maintenance in mice, in which the detailed phenotypes of adult cardiomyocyte-specific Wdr1 deletion mice had not been analyzed. In this study, we systematically analyzed the role of Wdr1 in adult mouse heart. Adult cardiomyocyte-specific Wdr1 deletion mice (cKO) exhibited cardiac hypertrophy and myocardial fibrosis. Echocardiographic study and electrocardiography revealed impaired contractile function, prolonged QT interval and Tpeak-Tend interval, and abnormal T-wave amplitude in cKO mice. Increased levels of sarcomeric proteins, adherens junction proteins and cofilin, and severe actin filament (F-actin) accumulations were observed in cKO mice heart. Taken together, this finding demonstrates that WDR1 is a critical factor for normal structure and function of adult mouse heart.

HAND2-mediated epithelial maintenance and integrity in cardiac outflow tract morphogenesis

During embryogenesis, epithelial organization is the prerequisite for organogenesis, in particular, for establishing the tubular structure. Recent studies provided hints about epithelial formation in early heart development, which has not been systemically explored. Here, we revealed a gradient of HAND2 protein in the cardiac progenitors in the anterior dorsal pericardial wall (aDPW) and adjacent transition zone (TZ) in the outflow tract (OFT). Deletion of Hand2 caused cell arrest and accumulation in the TZ leading to defective morphogenesis. While apicobasal cell polarity was unaffected, the key epithelial elements of adherens junction and cell-matrix adhesion were disrupted in the TZ of Hand2 mutant mice, indicating poorly formed epithelium. RNA-seq analysis revealed altered regulation of the contractile fiber and actin cytoskeleton, which affected cardiomyocyte differentiation. Furthermore, we have identified Stars as being transcriptionally controlled by HAND2. STARS facilitates actin polymerization that is essential for anchoring the adhesive molecules to create cell adhesion. Thus, we have uncovered a new function of HAND2 in mediating epithelial maintenance and integrity in OFT morphogenesis. Meanwhile, this study provides insights to understanding cardiac progenitor contribution to OFT development.