Wiskott-Aldrich Syndrome Protein Family Member Research Articles

PSIP1 promotes gefitinib resistance in lung adenocarcinoma by inducing the expression of WASF3 and its downstream ITGB3/AKT signaling.

Gefitinib (GR), a representative drug of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), is a key pillar in the treatment of lung adenocarcinoma (LUAD), but drug resistance is universal. Identifying the potential factors of drug resistance to GR is essential to treat patients with EGFR mutant LUAD. The GR-resistant LUAD cells were established and confirmed by MTT assay. The effects of PC4 and SRSF1 interacting protein 1 (PSIP1) on GR-resistant cell proliferation and apoptosis in vitro and in vivo were detected by colony formation, flow cytometry, tumor-bearing animal model, immunohistochemistry, and TUNEL staining. Western blotting and qPCR were used to determine the expression of relevant markers. The effect of PSIP1 on the promoter region of Wiskott-Aldrich syndrome protein family member 3 (WASF3) was detected by the dual-luciferase assay. The interaction between PSIP1 and RNA polymerase II was evaluated using ChIP-qPCR and Co-IP assays. PSIP1 was highly enriched in GR-resistant LUAD cells. Downregulation of PSIP1 expression significantly inhibited the proliferation of LUAD-resistant cells and promoted apoptosis. WASF3 was shown to have similar effects as PSIP1 in promoting drug resistance in LUAD cells. PSIP1 promoted the transcriptional activity of WASF3, which was achieved by increasing RNA polymerase II recruitment on the WASF3 promoter. Furthermore, PSIP1 positively regulated the expression of the pro-EGFR-TKI resistance factor integrin subunit beta 3 (ITGB3). Our work suggests that PSIP1 promotes resistance to GR in LUAD cells by inducing the expression of WASF3 and its downstream regulator ITGB3.

WAVE2 Is a Vital Regulator in Myogenic Differentiation of Progenitor Cells through the Mechanosensitive MRTFA-SRF Axis.

Skeletal myogenesis is an intricate process involving the differentiation of progenitor cells into myofibers, which is regulated by actin cytoskeletal dynamics and myogenic transcription factors. Although recent studies have demonstrated the pivotal roles of actin-binding proteins (ABPs) as mechanosensors and signal transducers, the biological significance of WAVE2 (Wiskott-Aldrich syndrome protein family member 2), an ABP essential for actin polymerization, in myogenic differentiation of progenitor cells has not been investigated. Our study provides important insights into the regulatory roles played by WAVE2 in the myocardin-related transcription factor A (MRTFA)-serum response factor (SRF) signaling axis and differentiation of myoblasts. We demonstrate that WAVE2 expression is induced during myogenic differentiation and plays a pivotal role in actin cytoskeletal remodeling in C2C12 myoblasts. Knockdown of WAVE2 in C2C12 cells reduced filamentous actin levels, increased globular actin accumulation, and impaired the nuclear translocation of MRTFA. Furthermore, WAVE2 depletion in myoblasts inhibited the expression and transcriptional activity of SRF and suppressed cell proliferation in myoblasts. Consequently, WAVE2 knockdown suppressed myogenic regulatory factors (i.e., MyoD, MyoG, and SMYD1) expressions, thereby hindering the differentiation of myoblasts. Thus, this study suggests that WAVE2 is essential for myogenic differentiation of progenitor cells by modulating the mechanosensitive MRTFA-SRF axis.

Proteomics associated with coronary high-risk plaque features on optical coherence tomography

Abstract Introduction Cardiovascular disease is the major cause of death worldwide. The physiological status of the cardiovascular system is reflected in plasma proteins and a newly developed technique based on proximity extension assays has enabled the analysis of a broad range of protein biomarkers associated with cardiovascular disease. However, biomarkers for coronary high-risk plaques, including lipid-rich plaques, macrophages, cholesterol crystals, and microvessels, have not yet been found. Purpose This study aimed to identify proteins specific for coronary high-risk plaques. Methods We analyzed 57 patients (71.1 ± 10.6 years, male: 68.4%) who underwent intracoronary optical coherence tomography and provided blood samples for proteomic analysis. Forty-seven patients (86.0%) had lipid-rich plaques, 46 patients (80.7%) had macrophages, 16 patients (28.1%) had cholesterol crystals, and 27 patients (47.4%) had microvessels. A total of 1,470 plasma proteins were analyzed using the Olink® Explore 1,536 Reagent Kit and P2 100 cycle reagent kit on a NextSeq 2000 sequencer. Results In patients with lipid-rich plaques, the protein expressions of Interstitial collagenase (MMP1), Wiskott-Aldrich syndrome protein family member 1 (WASF1), and Protein phosphatase 1 regulatory subunit 12A (PPP1R12RA) were significantly increased, while the expressions of Fc receptor-like protein 3 (FCRL3), Folate receptor gamma (FOLR3), Cobalamin binding intrinsic factor (CBLIF), Glutathione S-transferase A1 (GSTA1), and Keratin, type I cytoskeletal 18 (KRT18) were significantly decreased (Figure A). In patients with macrophages, the protein expressions of MMP1, WASF1, PPP1R12RA, and Scavenger receptor cysteine-rich domain-containing group B protein (SSC4D) were significantly increased, while the expressions of Fatty acid-binding protein, intestinal (FABP2), FOLR3, CBLIF, GSTA1, and Fibroblast growth factor 21 (FGF21) were significantly decreased (Figure B). In patients with cholesterol crystals, the protein expressions of FOLR3, Secreted frizzled-related protein 1 (SFRP1), and Anterior gradient protein 2 homolog (AGR2) were significantly decreased (Figure C). In patients with microvessels, the expression of FOLR3 was significantly decreased (Figure D). Conclusion These proteins might be new biomarkers in patients with coronary high-risk plaques.

WASF3 disrupts mitochondrial respiration and may mediate exercise intolerance in myalgic encephalomyelitis/chronic fatigue syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by various disabling symptoms including exercise intolerance and is diagnosed in the absence of a specific cause, making its clinical management challenging. A better understanding of the molecular mechanism underlying this apparent bioenergetic deficiency state may reveal insights for developing targeted treatment strategies. We report that overexpression of Wiskott-Aldrich Syndrome Protein Family Member 3 (WASF3), here identified in a 38-y-old woman suffering from long-standing fatigue and exercise intolerance, can disrupt mitochondrial respiratory supercomplex formation and is associated with endoplasmic reticulum (ER) stress. Increased expression of WASF3 in transgenic mice markedly decreased their treadmill running capacity with concomitantly impaired respiratory supercomplex assembly and reduced complex IV levels in skeletal muscle mitochondria. WASF3 induction by ER stress using endotoxin, well known to be associated with fatigue in humans, also decreased skeletal muscle complex IV levels in mice, while decreasing WASF3 levels by pharmacologic inhibition of ER stress improved mitochondrial function in the cells of the patient with chronic fatigue. Expanding on our findings, skeletal muscle biopsy samples obtained from a cohort of patients with ME/CFS showed increased WASF3 protein levels and aberrant ER stress activation. In addition to revealing a potential mechanism for the bioenergetic deficiency in ME/CFS, our study may also provide insights into other disorders associated with fatigue such as rheumatic diseases and long COVID.

An independent regulator of global release pathways in astrocytes generates a subtype of extracellular vesicles required for postsynaptic function.

Extracellular vesicles (EVs) are heterogeneous in size, composition, and function. We show that the six-transmembrane protein glycerophosphodiester phosphodiesterase 3 (GDE3) regulates actin remodeling, a global EV biogenic pathway, to release an EV subtype with distinct functions. GDE3 is necessary and sufficient for releasing EVs containing annexin A1 and GDE3 from the plasma membrane via Wiskott-Aldrich syndrome protein family member 3 (WAVE3), a major regulator of actin dynamics. GDE3 is expressed in astrocytes but not neurons, yet mice lacking GDE3 [Gde3 knockout (KO)] have decreased miniature excitatory postsynaptic current (mEPSC) amplitudes in hippocampal CA1 neurons. EVs from cultured wild-type astrocytes restore mEPSC amplitudes in Gde3 KOs, while EVs from Gde3 KO astrocytes or astrocytes inhibited for WAVE3 actin branching activity do not. Thus, GDE3-WAVE3 is a nonredundant astrocytic pathway that remodels actin to release a functionally distinct EV subtype, supporting the concept that independent regulation of global EV release pathways differentially regulates EV signaling within the cellular EV landscape.

Knockdown Wiskott-Aldrich syndrome protein family member 3 (WASF3) inhibits colorectal cancer metastasis and sensitizes to cisplatin through targeting ZNF471

Colorectal cancer (CRC) is a heterogeneous cancer, and many risk factors for colorectal cancer have been established. For CRC metastasis, tumor cell migration, adhesion as well as invasion are important processes. WiskottAldrich syndrome protein family member 3 (WASF3) is necessary for metastasis of various types of cancers. However, its role in CRC progression has not been fully elucidated. This study examined the in vitro functional roles of WASF3 in the CRC and explored the underlying molecular mechanisms. We used siRNA-WASF3 to gene silence WASF3 in colon cancer cell (HCT116) in vitro. The effects of WASF3 silencing on HCT116 cell apoptosis, proliferation, migration, as well as invasion were assessed by flow cytometry, CCK-8, and transwell assays. ZNF471 protein expressions were detected by immunofluorescence staining and RT-PCR. Moreover, the effects of ZNF471 were studied on a series of in vitro antitumor-promoting assays using HCT116. WASF3 knockdown expression using small interfering RNA (siRNA) ameliorated CRC cell proliferation, anchorage-independent growth, invasion, and metastasis. Furthermore, we observed that WASF3 contributed to upregulating the metastasis signaling pathway through inhibiting the expression of ZNF471. Our study suggests that targeting WASF3 signaling might be a novel therapeutic strategy for treating CRC.

Expansion of the Genotypic and Phenotypic Spectrum of WASF1-Related Neurodevelopmental Disorder

In humans, de novo truncating variants in WASF1 (Wiskott–Aldrich syndrome protein family member 1) have been linked to presentations of moderate-to-profound intellectual disability (ID), autistic features, and epilepsy. Apart from one case series, there is limited information on the phenotypic spectrum and genetic landscape of WASF1-related neurodevelopmental disorder (NDD). In this report, we describe detailed clinical characteristics of six individuals with WASF1-related NDD. We demonstrate a broader spectrum of neurodevelopmental impairment including more mildly affected individuals. Further, we report new variant types, including a copy number variant (CNV), resulting in the partial deletion of WASF1 in monozygotic twins, and three missense variants, two of which alter the same residue, p.W161. This report adds further evidence that de novo variants in WASF1 cause an autosomal dominant NDD.

Targeting WASF3 Signaling in Metastatic Cancer.

Increasing evidence indicates that cancer metastasis is regulated by specific genetic pathways independent of those controlling tumorigenesis and cancer growth. WASF3, a Wiskott–Aldrich syndrome protein family member, appears to play a major role not only in the regulation of actin cytoskeleton dynamics but also in cancer cell invasion/metastasis. Recent studies have highlighted that WASF3 is a master regulator and acts as a pivotal scaffolding protein, bringing the various components of metastatic signaling complexes together both spatially and temporally. Herein, targeting WASF3 at the levels of transcription, protein stability, and phosphorylation holds great promise for metastasis suppression, regardless of the diverse genetic backgrounds associated with tumor development. This review focuses on the critical and distinct contributions of WASF3 in the regulation of signal pathways promoting cancer cell invasion and metastasis.

WASF3 Knockdown Sensitizes Gastric Cancer Cells to Oxaliplatin by Inhibiting ATG12-Mediated Autophagy

BackgroundGastric cancer is one of the most aggressive tumors, usually resulting in metastasis, and therapies for advanced gastric cancer remain limited. Drug resistance is the main reason for chemotherapeutic failure in gastric cancer. Wiskott-Aldrich syndrome protein family member 3 (WASF3) is required for invasion and metastasis of different cancers. However, there has been little study of WASF3 expression involvement in gastric cancer. In this study, we explored the role of WASF3 in the sensitivity of gastric cancer to oxaliplatin, and the underlying mechanisms. MethodsWe silenced WASF3 using WASF3-siRNA in MGC803 cells. Then, CCK-8, flow cytometry and transwell assay were performed to study the effect of WASF3 silencing on proliferation, migration, invasiveness and apoptosis of MGC803 cells. Moreover, we evaluated the potential mechanism in vitro to determine the sensitization to oxaliplatin induced by WASF3. ResultsWASF3 silencing by small interfering RNA inhibited the proliferation, migration and invasiveness of gastric cancer cells. We also observed that WASF3 knockdown promoted cell apoptosis and enhanced oxaliplatin sensitivity. Furthermore, the sensitization to oxaliplatin induced by WASF3 knockdown depended on the inhibition of Atg12-mediated autophagy. ConclusionsOur analysis demonstrates WASF3 targeting is a new potential therapeutic strategy for gastric cancer.

Wasf3 Deficiency Reveals Involvement in Metastasis in a Mouse Model of Breast Cancer

The WASF3 gene has been implicated in cancer cell movement, invasion, and metastasis by regulating genetic pathways important in these processes. Invasion and metastasis assays, however, are largely centered on xenograft models in immune-compromised mice. To facilitate analysis of the role of WASF3 in the spontaneous development of cancer cell metastasis, we generated a Wasf3 null strain by deleting exons 4 and 5, which encode essential motifs for Wasf3 function. On exposure to cre-recombinase a stop codon is generated immediately downstream in exon 6. Using a cytomegalovirus (CMV)-cre strain, Wasf3 constitutively was inactivated, which led to viable mice with no visible morphologic or behavioral abnormalities. There was no abnormal development or function of the mouse mammary gland in the Wasf3 null mice and brain development was normal. In the mouse mammary tumor virus (MMTV)-driven polyoma middle-T oncogene strain, which shows early onset breast cancer development and metastasis, Wiskott-Aldrich syndrome protein family member 3 (Wasf3) is up-regulated in metastatic lesions. When this oncogene was introduced onto the Wasf3-null background, although metastasis was observed in these mice, there was a reduction in the number and size of metastatic lesions in the lungs. These data provide evidence for a role in WASF3 in the development of metastasis in a spontaneous model of breast cancer.

Yes-associated protein promotes cell migration via activating Wiskott-Aldrich syndrome protein family member 1 in oral squamous cell carcinoma.

Yes-associated protein (YAP) is a candidate oncogene in various cancers including oral squamous cell carcinoma (OSCC). Our previous study demonstrated that TNF-alpha could inhibit cell proliferation and invasion by YAP phosphorylation in OSCC. However, the role of YAP in OSCC is not yet clear. The objective of the present study was to elucidate the function of YAP in promoting migration in OSCC and to explore the possible mechanism with a novel YAP inhibitor CA3. A total of 68 OSCC patients were enrolled, and the expression levels of YAP were investigated in tissue specimens by immunohistochemical staining. The inhibitory effects of CA3, a novel inhibitor of YAP, were demonstrated by immunofluorescence, Western blotting, and transwell assays. A human PCR motility array was performed to screen the changes in the gene expression profiles of the cells. In addition, shRNA interference, YAP re-expression, and WAVE1 overexpression plasmids were used to detect the regulatory mechanism of YAP and its relationship with cell migration. Yes-associated protein nuclear expression levels were associated with metastasis and 5-year overall survival rate. CA3 exhibited potent inhibitory effects on OSCC migration. YAP knockdown significantly suppressed tumor cell migration in OSCC. These effects were rescued when YAP was re-expressed and during WAVE1 overexpression in YAP-shRNA stable cells. The present study revealed that YAP was associated with cell migration and that this process was regulated by YAP/WAVE1. We also demonstrated that CA3 exhibited marked inhibitory effects on YAP expression and that it could be considered a potential therapeutic target for the treatment of OSCC.

WASH overexpression enhances cancer stem cell properties and correlates with poor prognosis of esophageal carcinoma.

There is increasing evidence that cytoskeleton remodeling is involved in cancer progression. Wiskott‐Aldrich syndrome protein (WASP) family represents a key regulator of actin cytoskeleton remodeling. However, the underlying mechanism of the WASP family in cancer progression remains elusive. Here, we studied the role of WASP and SCAR Homolog (WASH), a recently identified WASP family member, in human esophageal squamous cell carcinoma (ESCC). Using three human ESCC cell lines, we found that WASH expression was significantly elevated in cancer stem‐like cells enriched by sphere formation assay. WASH knockdown decreased the sphere‐forming capacity of esophageal cancer cells whereas WASH over‐expression exhibited the opposite effect. Mechanistically, we identified interleukin‐8 (IL‐8) as a key downstream target of WASH. IL‐8 knockdown completely attenuated tumor sphere formation induced by WASH overexpression. WASH knockdown also delayed the growth of human ESCC xenografts in BALB/c nude mice. Importantly, high WASH levels were associated with poor clinical prognosis in a total of 145 human ESCC tissues. Collectively, our results suggest an essential role of the WASH/IL‐8 pathway in human ESCC by maintaining the stemness of cancer cells. Hence, targeting this pathway might represent a promising strategy to control human esophageal carcinoma.

Secreted gelsolin desensitizes and induces apoptosis of infiltrated lymphocytes in prostate cancer.

Loss of immunosurveillance is a major cause of cancer progression. Here, we demonstrate that gelsolin, a constituent of ejaculate, induces apoptosis of activated lymphocytes in prostate cancer. Gelsolin was highly expressed in prostate cancer cells, and was associated with tumor progression, recurrence, metastasis, and poor prognosis. In vitro, secreted gelsolin inactivated CD4+ T cells by binding to CD37, and induced apoptosis of activated CD8+ T lymphocytes by binding to Fas ligand during cell contact dependent on major histocompatibility complex I. Moreover, secreted gelsolin bound to sortilin, which in turn bound to Wiskott-Aldrich syndrome protein family member 3, thereby enhancing the endocytosis and intracellular transport of essential lipids needed to facilitate tumor growth and expansion. Under normal conditions, gelsolin is a seemingly harmless protein that prevents immune responses in female recipients. In disease states, however, this protein can inhibit immunosurveillance and promote cancer progression.

Cellular functions of WASP family proteins at a glance.

Proteins of the Wiskott-Aldrich syndrome protein (WASP) family function as nucleation-promoting factors for the ubiquitously expressed Arp2/3 complex, which drives the generation of branched actin filaments. Arp2/3-generated actin regulates diverse cellular processes, including the formation of lamellipodia and filopodia, endocytosis and/or phagocytosis at the plasma membrane, and the generation of cargo-laden vesicles from organelles including the Golgi, endoplasmic reticulum (ER) and the endo-lysosomal network. Recent studies have also identified roles for WASP family members in promoting actin dynamics at the centrosome, influencing nuclear shape and membrane remodeling events leading to the generation of autophagosomes. Interestingly, several WASP family members have also been observed in the nucleus where they directly influence gene expression by serving as molecular platforms for the assembly of epigenetic and transcriptional machinery. In this Cell Science at a Glance article and accompanying poster, we provide an update on the subcellular roles of WHAMM, JMY and WASH (also known as WASHC1), as well as their mechanisms of regulation and emerging functions within the cell.

Kinesin Light Chain (KLC)의 Tetratricopeptide Repeat (TPR) 도메인을 통한 Scaffold 단백질 WAVE1과 Kinesin 1의 결합

Kinesin superfamily proteins (KIFs)은 세포 내 소기관이나 단백질복합체를 미세소관을 따라 운반하는 모터단백질이다. Kinesin 1은 경쇄단위체(light chain subunit)를 통하여 결합함으로써 세포 내 소기관, 신경소포, 신경전달물질수용체, 신호전달단백질, mRNA 등 다양한 운반체를 운반하는 KIFs의 한 종류이다. Kinesin light chains (KLCs)은 모터기능이 없는 단위체로서 kinesin heavy chains (KHCs) 이량체와 결합하여 kinesin 1을 구성한다. KLCs은 여러 단백질과 결합하지만 아직 결합단백질이 충분히 밝혀지지 않았다. 본 연구에서 KLC1의 tetratricopeptide repeat (TPR) 영역과 결합하는 단백질을 분리하기 위하여 효모 two-hybrid 탐색을 수행한 결과 Wiskott-Aldrich syndrome의 원인단백질이며 액틴 세포골격 조절단백질인 WASP/WAVE family의 하나인 WAVE1을 분리하였다. WAVE1은 KLC1의 TPR 영역을 포함한 부위와 결합하지만 KHCs인 KIF5A, KIF5B, KIF5C와는 결합하지 않았다. 또한 KLC1은 WAVE1의 C-말단에 존재하는 verprolin/cofilin/acidic (VCA) 도메인과 결합하였으며, 다른 WAVE isoform인 WAVE2와 WAVE3과도 결합하였다. HEK-293T 세포에 WAVE1과 KLC1을 동시에 발현시켰을 때 두 단백질이 세포 내에서 같은 부위에 존재하며, WAVE1을 면역침강한 결과 KLC1뿐만 아니라 KIF5B가 같이 침강함을 확인하였다. 이러한 결과들은 kinesin 1이 WAVE 단백질복합체 혹은 WAVE로 덮여있는 운반체를 운반함을 시사한다. Kinesin superfamily proteins (KIFs) are microtubule-dependent molecular motor proteins essential for the intracellular transport of organelles and protein complexes in cells. Kinesin 1 is a member of those KIFs that transport various cargoes, including organelles, synaptic vesicles, neurotransmitter receptors, cell signaling molecules, and mRNAs through interaction between its light chain subunit and the cargoes. Kinesin light chains (KLCs) are non-motor subunits that associate with the kinesin heavy chain (KHC) dimer. KLCs interact with many different binding proteins, but their particular binding proteins have not yet been fully identified. We used the yeast two-hybrid assay to identify proteins that interact with the tetratricopeptide repeat (TPR) domain of KLC1. We found an interaction between the TPR domain of KLC1 and Wiskott-Aldrich syndrome protein family member 1 (WAVE1), a member of the WASP/WAVE family involved in regulation of actin cytoskeleton. WAVE1 bound to the six TPR domain-containing regions of KLC1 and did not interact with KHCs (KIF5A, KIF5B, and KIF5C) in the yeast two-hybrid assay. The carboxyl (C)-terminal verprolin-cofilin-acidic (VCA) domain of WAVE1 is essential for interaction with KLC1. Also, other WAVE isoforms (WAVE2 and WAVE3) interacted with KLC1 in the yeast two-hybrid assay. When co-expressed in HEK-293T cells, WAVE1 co-localized with KLC1 and co-immunoprecipitated with KLC1 and KIF5B. These results suggest that kinesin 1 motor protein may transport WAVE complexes or WAVE-coated cargoes in cells.

Somatic Mutations in the Wiskott-Aldrich Syndrome Protein Family Member 3 (WASF3) Are Associated with Poor Prognosis in Myeloid Malignancies

Myelodysplastic syndromes (MDS) encompass a clinically and pathologically heterogeneous group of blood cancers characterized by dysplasia, cytopenias, and a significant risk for transformation to acute myeloid leukemia (AML). The understanding of MDS biology is the key to deciphering disease pathogenesis and offers the ability to identify specific pathways that may be important for diagnosis, prognosis, and most importantly for designing new targets amenable to therapies. Genetic factors specifically molecular mutations in genes involved in many important cellular processes such as epigenetics, signaling, and RNA splicing have been identified in MDS. These mutations affect disease pathogenesis and are prognostic. Whole exome sequencing (WES) technologies have advanced genomic discoveries in MDS. We applied WES on 2 ug of DNA of 14 patients (pts) (MDS=11 and MF=3). Non clonal CD3+ cells served as germline control. 20 million reads were run on an Illumina HiSeq2000 sequencer. A stringent bio-informatic algorithm filtered all variants based on a variation score (>=30) and a coverage (30X). Tumor nucleotide variation analysis was performed for each pair (tumor vs. germline), where only variants unique to the tumor were retained after the exclusion of SNPs. Using this tool, we discovered the first recurrent somatic mutation (R178H) in a Wiskott-Aldrich syndrome protein (WASP) family of genes specifically Wiskott-Aldrich syndrome protein family member 3 (WASF3) also known as WAVE-3 in a pt with MDS. Further analysis by Sanger sequencing on a larger cohort of pts with myeloid neoplasms [n=241; (MDS= RARS/RCMD: n=30; RAEB1/2: n=49); primary AML (n=42), CMML1/2 (n=30), MPN (MF, ET, PV, CML: n=90)] showed WASF3 mutations in 5/49 (10%) higher risk MDS and 2/25 (8%) JAK2WT PV pts. MDS pts with WASF3 mutations (WASF3MUT) had higher peripheral (3.7% vs. 0.5%, P = .002) and bone marrow blasts % (4.7% vs. 1.4%, P = .005), and lower PLT count (71 vs. 191 k/uL, P = .005) compared to WASF3WT pts. Molecular analysis for a panel of genes known to be mutated in MDS and MPN like ASXL1, U2AF1, SRSF2, SF3B1 and IDH1/2 showed that 2/7 WASF3MUT carried also SRSF2 mutations (P95R/L). WASF3 mutations had a negative impact on the survival outcomes. Indeed WASF3MUT pts had a shorter overall survival (OSMut 10.5 mos vs. OSWT 29.1 mos, P=.01) and progression free survival (PFSMUT 5.1 mos vs. 15.9 PFSWT mos, P = .03) compared to WASF3WT pts. WASF3MUT MDS pts also carried worse OS compared to pts with MDS and normal karyotype (14 mos vs. 41.8 mos, P =.019) and SF3B1MUT which are known to carry a good prognostic outcome in MDS (14 mos vs. 54.1 mos, P =.003). Western blotting showed increased WASF3 protein expression in the index case compared to WASF3WT pts (n=2). We performed microarray analysis on 6 higher risk MDS and 6 MPN pts, with one pt harboring the WASF3 mutation. Illumina Human HT-12 v4 expression beadchips were used to estimate mRNA expression levels. The WASF3R178H mutant pt had a higher WASF3 mRNA expression compared to 2 matched WT pts (Fold Change [FC] =1.44, P=.16). Further, protein complex pathways, specifically, Arp2/3, which has been shown to interact with WASF3 and other WASF family members also showed similar patterns of expression. ARP2 (ACTR2) and ARP3 (ACTR3) were both elevated in WASF3MUT vs. WT (ACTR2: FC=1.79, P=.029; ACTR3: FC=1.60, P=.144). We also found that WAS, which encodes the WASP protein, was expressed in our MDS samples and shows elevated expression in WASF3MUT vs. WT (FC=1.58, P = .05). This suggests that other members of the WASP family of proteins may be involved in MDS pathogenesis. WASP was originally found to be mutated in Wiskott Aldrich syndrome (WAS), an X-linked recessive immunodeficiency disorder. Mutations in this gene are important in actin polymerization, a process essential for cytokinesis, chromosome segregation, endocytosis, migration, and formation of filopodia and lamellipodia. In prostate and breast cancers, overexpression of WASF3 has been associated with increased disease metastasis and tumor invasion and treatment resistance. In conclusion, WASF3 somatic mutations are found in MDS and MPN pts and associated with increased mRNA/ protein expression. The presence of WASF3 mutations is associated with poor survival in myeloid malignancies. Understanding the mechanism by which WASF3 gene act may provide new targeted therapeutic options for myeloid cancers which harbor this mutation. DisclosuresNo relevant conflicts of interest to declare.

IL-17A regulates Eimeria tenella schizont maturation and migration in avian coccidiosis

Although IL17A is associated with the immunological control of various infectious diseases, its role in host response to Eimeria infections is not well understood. In an effort to better dissect the role of IL17A in host-pathogen interactions in avian coccidiosis, a neutralizing antibody (Ab) to chicken IL17A was used to counteract IL17A bioactivity in vivo. Chickens infected with Eimeria tenella and treated intravenously with IL17A Ab, exhibited reduced intracellular schizont and merozoite development, diminished lesion score, compared with untreated controls. Immunohistological evaluation of cecal lesions in the parasitized tissues indicated reduced migration and maturation of second-generation schizonts and reduced lesions in lamina propria and submucosa. In contrast, untreated and infected chickens had epithelial cells harboring second-generation schizonts, which extend into the submucosa through muscularis mucosa disruptions, maturing into second generation merozoites. Furthermore, IL17A Ab treatment was associated with increased parameters of Th1 immunity (IL2- and IFNγ- producing cells), reduced levels of reactive oxygen species (ROS), and diminished levels of serum matrix metalloproteinase-9 (MMP-9). Finally, schizonts from untreated and infected chickens expressed S100, Wiskott-Aldrich syndrome protein family member 3 (WASF3), and heat shock protein-70 (HSP70) proteins as merozoites matured, whereas the expression of these proteins was absent in IL17A Ab-treated chickens. These results provide the first evidence that the administration of an IL17A neutralizing Ab to E. tenella-infected chickens inhibits the migration of parasitized epithelial cells, markedly reduces the production of ROS and MMP-9, and decreases cecal lesions, suggesting that IL17A might be a potential therapeutic target for coccidiosis control.

Nuclear Wave1 Is Required for Reprogramming Transcription in Oocytes and for Normal Development

Eggs and oocytes have a remarkable ability to induce transcription of sperm after normal fertilization and in somatic nuclei after somatic cell nuclear transfer. This ability of eggs and oocytes is essential for normal development. Nuclear actin and actin-binding proteins have been shown to contribute to transcription, although their mode of action is elusive. Here, we find that Xenopus Wave1, previously characterized as a protein involved in actin cytoskeleton organization, is present in the oocyte nucleus and is required for efficient transcriptional reprogramming. Moreover, Wave1 knockdown in embryos results in abnormal development and defective hox gene activation. Nuclear Wave1 binds by its WHD domain to active transcription components, and this binding contributes to the action of RNA polymerase II. We identify Wave1 as a maternal reprogramming factor that also has a necessary role in gene activation in development.

Wasf2: A novel target of intermittent parathyroid hormone administration

Systemic intermittent administration of parathyroid hormone (PTH) stimulates bone formation in animals and humans, and recombinant human PTH1-34 (teriparatide) is used clinically for the treatment of osteoporosis. In this study, we investigated the regulation of gene expression by intermittent PTH administration in MC3T3-E1 osteoblastic cells. We found that intermittent PTH1-34 administration downregulated Wiskott-Aldrich syndrome protein family member (Wasf) 2 mRNA expression. Wnt inhibitor, IWP-2, and protein kinase C inhibitor, Go6976, inhibited this downregulation. However, continuous PTH did not affect Wasf2 expression. Transfection of Wasf2 siRNA reduced bone sialoprotein (BSP) mRNA expression in a similar manner following intermittent PTH administration in MC3T3-E1 cells. These results identify Wasf2 as a novel target of intermittent PTH administration via the Wnt and phosphoinositide-dependent protein kinase signaling pathways, and the resulting regulation of BSP expression may contribute to the anabolic effects of PTH.

WASH and WAVE actin regulators of the Wiskott–Aldrich syndrome protein (WASP) family are controlled by analogous structurally related complexes

We recently showed that the Wiskott-Aldrich syndrome protein (WASP) family member, WASH, localizes to endosomal subdomains and regulates endocytic vesicle scission in an Arp2/3-dependent manner. Mechanisms regulating WASH activity are unknown. Here we show that WASH functions in cells within a 500 kDa core complex containing Strumpellin, FAM21, KIAA1033 (SWIP), and CCDC53. Although recombinant WASH is constitutively active toward the Arp2/3 complex, the reconstituted core assembly is inhibited, suggesting that it functions in cells to regulate actin dynamics through WASH. FAM21 interacts directly with CAPZ and inhibits its actin-capping activity. Four of the five core components show distant (approximately 15% amino acid sequence identify) but significant structural homology to components of a complex that negatively regulates the WASP family member, WAVE. Moreover, biochemical and electron microscopic analyses show that the WASH and WAVE complexes are structurally similar. Thus, these two distantly related WASP family members are controlled by analogous structurally related mechanisms. Strumpellin is mutated in the human disease hereditary spastic paraplegia, and its link to WASH suggests that misregulation of actin dynamics on endosomes may play a role in this disorder.