PAK1 Research Articles

ACSL4 promotes malignant progression of Hepatocellular carcinoma by targeting PAK2 transcription

Long-chain fatty acyl-Coa ligase 4 (ACSL4) is an important enzyme that converts fatty acids to fatty acyl-Coa esters, there is increasing evidence for its role in carcinogenesis. However, the precise role of ACLS4 in hepatocellular carcinoma (HCC) is not clearly understood. In the present study, we provide evidence that ACSL4 expression was specifically elevated in HCC and is associated with poor clinical outcomes. ACSL4 significantly promotes the growth and metastasis of HCC both in vitro and in vivo. RNA sequencing and functional experiments showed that the effect of ACSL4 on HCC development was heavily dependent on PAK2. ACSL4 expression is well correlated with PAK2 in HCC, and ACSL4 even transcriptionally increased PAK2 gene expression mediated by Sp1. In addition, emodin, a naturally occurring anthraquinone derivative, inhibited HCC cell growth and tumor progression by targeting ACSL4. In summary, ACSL4 plays a novel oncogene in HCC development by regulating PAK2 transcription. Targeting ACSL4 could be useful in drug development and therapy for HCC.

The Dynamics of Gene Expression Unraveling the Immune Response of Macrobrachium rosenbergii Infected by Aeromonas veronii.

To further investigate the immune response of Macrobrachium rosenbergii against Aeromonas veronii, comparative transcriptomic analyses of the M. rosenbergii hepatopancreas were conducted on challenge and control groups at 6, 12, and 24 h post-infection (hpi), independently. A total of 51,707 high-quality unigenes were collected from the RNA-seq data, and 8060 differentially expressed genes (DEGs) were discovered through paired comparisons. Among the three comparison groups, a KEGG pathway enrichment analysis showed that 173 immune-related DEGs were considerably clustered into 28 immune-related pathways, including the lysosome, the phagosome, etc. Moreover, the expression levels of the four key immune-related genes (TOLL, PAK1, GSK3β, and IKKα) were evaluated at various stages following post-infection in the hepatopancreas, hemolymph, and gills. Both PAK1 and GSK3β genes were highly up-regulated in all three tissues at 6 hpi with A. veronii; TOLL was up-regulated in the hepatopancreas and hemolymph but down-regulated in the gill at 6 hpi, and IKKα was up-regulated in hemolymph and gill, but down-regulated in the hepatopancreas at 6 hpi. These findings lay the groundwork for understanding the immune mechanism of M. rosenbergii after contracting A. veronii.

Recurrent PAK2 rearrangements in poroma with folliculo-sebaceous differentiation.

Poroma is a benign adnexal neoplasm with differentiation towards the upper portion of the sweat gland apparatus. In 2019, Sekine etal. demonstrated recurrent YAP1::MAML2 and YAP1::NUTM1 fusion in poroma and porocarcinoma. Follicular, sebaceous and/or apocrine differentiation has been reported in rare cases of poroma and whether these tumours constitute a variant of poroma or represent a distinctive tumour is a matter to debate. Herein we describe the clinical, immunophenotypic, and molecular features of 13 cases of poroma with folliculo-sebaceous differentiation. Most of the tumours were located on the head and neck region (n = 7), and on the thigh (n = 3). All presented were adults with a slight male predilection. The median tumour size was 10 mm (range: 4-25). Microscopically, lesions displayed features of poroma with nodules of monotonous basophilic cells associated with a second population of larger eosinophilic cells. In all cases, ducts and scattered sebocytes were identified. Infundibular cysts were present in 10 cases. In two cases high mitotic activity was noted, and in three cases cytologic atypia and areas of necrosis were identified. Whole transcriptome RNA sequencing demonstrated in-frame fusion transcripts involving RNF13::PAK2 (n = 4), EPHB3::PAK2 (n = 2), DLG1::PAK2 (n = 2), LRIG1::PAK2 (n = 1), ATP1B3::PAK2 (n = 1), TM9SF4::PAK2 (n = 1), and CTNNA1::PAK2 (n = 1). Moreover, fluorescence in situ hybridisation (FISH) analysis revealed PAK2 rearrangement in an additional case. No YAP1::MAML2 or YAP1::NUTM1 fusion was detected. Recurrent fusions involving the PAK2 gene in all analysed poroma with folliculo-sebaceous differentiation in this study confirms that this neoplasm represents a separate tumour entity distinct from YAP1::MAML2 or YAP1::NUTM1 rearranged poromas.

A de novo PAK1 likely pathogenic variant and a de novo terminal 1q microdeletion in a Chinese girl with global developmental delay, severe intellectual disability, and seizures

BackgroundPathogenic PAK1 variants were described to be causative of neurodevelopmental disorder with macrocephaly, seizures, and speech delay. Herein, we present a de novo PAK1 variant combine with a de novo terminal 1q microdeletion in a Chinese pediatric patient, aiming to provide more insights into the underlying genotype–phenotype relationship.MethodsEnrolled in this study was a 6-year-old girl with clinical features of global developmental delay, severe intellectual disability, speech delay, and seizures from Quanzhou region of China. Karyotype and chromosomal microarray analysis (CMA) were performed to detect chromosome abnormalities in this family. Whole exome sequencing (WES) was performed to investigate additional genetic variants in this family.ResultsNo chromosomal abnormalities were elicited from the entire family by karyotype analysis. Further familial CMA results revealed that the patient had a de novo 2.7-Mb microdeletion (arr[GRCh37] 1q44(246,454,321_249,224,684) × 1]) in 1q44 region, which contains 14 OMIM genes, but did not overlap the reported smallest region of overlap (SRO) responsible for the clinical features in 1q43q44 deletion syndrome. In addition, WES result demonstrated a de novo NM_002576: c.251C > G (p.T84R) variant in PAK1 gene in the patient, which was interpreted as a likely pathogenic variant.ConclusionIn this study, we identify a novel PAK1 variant associated with a terminal 1q microdeletion in a patient with neurodevelopmental disorder. In addition, we believe that the main clinical features may ascribe to the pathogenic variant in PAK1 gene in the patient.

PAK1 overexpression promotes myxofibrosarcoma angiogenesis through STAT5B-mediated CSF2 transactivation: clinical and therapeutic relevance of amplification and nuclear entry.

Myxofibrosarcoma is genetically complex without established nonsurgical therapies. In public datasets, PAK1 was recurrently gained with mRNA upregulation. Using myxofibrosarcoma cells, we explored the oncogenic underpinning of PAK1 with genetic manipulation and a pan-PAK inhibitor (PF3758309). Myxofibrosarcoma specimens were analyzed for the levels of PAK1, phospho-PAKT423, CSF2 and microvascular density (MVD) and those of PAK1 gene and mRNA. PAK1-expressing xenografts were assessed for the effects of PF3758309 and CSF2 silencing. Besides pro-proliferative and pro-migrator/pro-invasive attributes, PAK1 strongly enhanced angiogenesis in vitro, which, not phenocopied by PAK2-4, was identified as CSF2-mediated using antibody arrays. PAK1 underwent phosphorylation at tyrosines153,201,285 and threonine423 to facilitate nuclear entry, whereby nuclear PAK1 bound STAT5B to co-transactivate the CSF2 promoter, increasing CSF2 secretion needed for angiogenesis. Angiogenesis driven by PAK1-upregulated CSF2 was negated by CSF2 silencing, anti-CSF2, and PF3758309. Clinically, overexpressed whole-cell phospho-PAKT423, related to PAK1 amplification, was associated with increased grades, stages, and PAK1 mRNA, higher MVD, and CSF2 overexpression. Overexpressed whole-cell phospho-PAKT423 and CSF2 independently portended shorter metastasis-free survival and disease-specific survival, respectively. In vivo, both CSF2 silencing and PF3758309 suppressed PAK1-driven tumor proliferation and angiogenesis. Conclusively, the nuclear entry of overexpressed/activated PAK1 endows myxofibrosarcomas with pro-angiogenic function, highlighting the vulnerable PAK1/STAT5B/CSF2 regulatory axis.

Bone Marrow Mesenchymal Stem Cells Modified with microRNA-216a-5p Enhance Proliferation of Acinar Cells in Severe Acute Pancreatitis

This study assesses the effect of bone marrow mesenchymal stem cells (BMSC) modified with miR-216a-5p on acinar cell proliferation in SAP. 40 rats were equally assigned into miR-NC set, miR-216a-5p set, BMSC set and anti-miR-216a-5p set randomly. The SAP model was prepared using AR42J cells which were disposed with CAE. Cells were transfected with lipidosome method to meaure miR-216-5p by RT-PCR, cell proliferation by CCK-8 along with analysis of cell clone formation and apoptosis. miR-216a-5p in modified BMSC was significantly upregulated compared with BMSC, indicating that BMSC was modified with miR-216a-5p successfully. BMSC modified with miR-216a-5p significantly promoted cell proliferation and clone formation and decreased apoptosis. The luciferase activity in wild type of miR-216a-5p was reduced, indicating that miR-216-5p could target Pak2 gene. In conclusion, proliferation of acinar cells in SAP is prompted and apoptosis ise reduced by BMSC modified with miR-216a-5p, which is possibly through targeting PAK2 gene.

MiR-7 Regulates Pathogen-Induced Immune Response via PAK1 in the Sea Cucumber Apostichopus japonicus.

MicroRNA-7 (miR-7) is a highly conserved short non-coding RNA involved in various bioprocesses via the regulation of multiple target genes. To enrich our knowledge of the functions of miR-7 in innate immune regulation in echinoderms, we first investigated the targeting relationship between miR-7 and PAK1 in the sea cucumber Apostichopus japonicus and then explored the functions of miR-7, the PAK1 gene, and the miR-7/PAK1 axis in the pathogen-induced immune response of A. japonicus. Our results showed that miR-7 can bind to the 3ʹUTR of PAK1 and negatively regulate the expression of PAK1 in A. japonicus. Overexpression and inhibition of miR-7 and inhibition of the expression of PAK1 can alter phagocytosis, cellular agglutination, and lysozyme contents in A. japonicus. Both miR-7 and the PAK1 gene are involved in immune defense against Vibrio splendidus infection; the miR-7/AjPAK1 axis showed immune regulatory function at 48 to 72 h post-infection (hpi) after V. splendidus infection in A. japonicus. In summary, the results of this study established that miR-7 regulates the pathogen-induced immune response by targeting PAK1 in A. japonicus.

The role of miRNA-571 and miRNA-559 in lung cancer by affecting the expression of genes associated with the ErbB signaling pathway

BackgroundAbnormal expression and activity of the ErbB pathway has been revealed in many cancers, such as lung cancer. The inappropriate activity of EGFR, MAPK1 and PAK2 receptors play an important role in cancer progression. MiRNAs are small non-protein encoding RNAs that act as negative endogenous regulators in various diseases. In this study, our aim was to investigate the effects of miR-571 and miR-559 on the expression of EGFR, MAPK1 and PAK2 genes related to the ErbB signaling pathway. MethodsAfter culture of A549 lung cancer cells, miRNAs were transfected into cells by lipofectamine and incubated for 24, 48 and 72 h. Expression of EGFR, MAPK1 and PAK2 genes was analyzed using quantitative real time PCR (RT-qPCR). ResultsThe effect of miR-571 was significant after 48 h of incubation of A549 cells. The expression of EGFR, MAPK1 and PAK2 genes was decreased by 2.2 fold (p < 0.001), 3.5 fold (p < 0.0001) and 2.4 fold (p < 0.0001), respectively. After 72 h of incubation, the expression of PAK2 gene was significantly decreased (p = 0.003). Moreover, the miR-559 had not significant effect on the expression of genes after 24, 48 and 72 h. ConclusionInhibition of the ErbB signaling pathway by targeting the expression of EGFR, MAPK1, PAK2 by miR-571 can be an important advance in the targeted treatment of lung cancer. High expression of miR-571 could significantly inhibit cancer cell proliferation and induce apoptosis. Due to the irregular activity of the ErbB pathway in many cancers, the results of this study can be used as a therapeutic line for other cancers.

High tumour mutational burden and EGFR/MAPK pathway activation are therapeutic targets in metastatic porocarcinoma.

Eccrine porocarcinoma (EPC) is a rare skin cancer arising from the eccrine sweat glands. Due to the lack of effective therapies, metastasis is associated with a high mortality rate. To investigate the drivers of EPC progression. We carried out genomic and transcriptomic profiling of metastatic EPC (mEPC), validation of the observed alterations in an EPC patient-derived cell line, confirmation of relevant observations in a large patient cohort of 30 tumour tissues, and successful treatment of a patient with mEPC under the identified treatment regimens. mEPC was characterized by a high tumour mutational burden (TMB) with an ultraviolet signature, widespread copy number alterations and gene expression changes that affected cancer-relevant cellular processes such as cell cycle regulation and proliferation, including a pathogenic TP53 (tumour protein 53) mutation, a copy number deletion in the CDKN2A (cyclin dependent kinase inhibitor 2A) region and a CTNND1/PAK1 [catenin delta 1/p21 (RAC1) activated kinase 1] gene fusion. The overexpression of EGFR (epidermal growth factor receptor), PAK1 and MAP2K1 (mitogen-activated protein kinase kinase 1; also known as MEK1) genes translated into strong protein expression and respective pathway activation in the tumour tissue. Furthermore, a patient-derived cell line was sensitive to EGFR and MEK inhibition, confirming the functional relevance of the pathway activation. Immunohistochemistry analyses in a large patient cohort showed the relevance of the observed changes to the pathogenesis of EPC. Our results indicate that mEPC should respond to immune or kinase inhibitor therapy. Indeed, the advanced disease of our index patient was controlled by EGFR-directed therapy and immune checkpoint inhibition for more than 2years. Molecular profiling demonstrated high TMB and EGFR/MAPK pathway activation to be novel therapeutic targets in mEPC.

Dominant monoallelic variant in the PAK2 gene causes Knobloch syndrome type 2.

Knobloch syndrome is an autosomal recessive phenotype mainly characterized by retinal detachment and encephalocele caused by biallelic pathogenic variants in the COL18A1 gene. However, there are patients clinically diagnosed as Knobloch syndrome with unknown molecular etiology not linked to COL18A1. We studied an historical pedigree (published in 1998) designated as KNO2 (Knobloch type 2 syndrome with intellectual disability, autistic behavior, retinal degeneration, encephalocele). Whole exome sequencing of the two affected siblings and the normal parents resulted in the identification of a PAK2 non-synonymous substitution p.(Glu435Lys) as a causative variant. The variant was monoallelic and apparently de novo in both siblings indicating a likely germ-line mosaicism in one of the parents; the mosaicism, however, could not be observed after deep sequencing of blood parental DNA. PAK2 encodes a member of a small group of serine/threonine kinases; these P21-activating kinases (PAKs) are essential in signal transduction and cellular regulation (cytoskeletal dynamics, cell motility, death and survival signaling and cell cycle progression). Structural analysis of the PAK2 p.(Glu435Lys) variant that is located in the kinase domain of the protein predicts a possible compromise in the kinase activity. Functional analysis of the p.(Glu435Lys) PAK2 variant in transfected HEK293T cells results in a partial loss of the kinase activity. PAK2 has been previously suggested as an autism-related gene. Our results show that PAK2-induced phenotypic spectrum is broad and not fully understood. We conclude that the KNO2 syndrome in the studied family is dominant and caused by a deleterious variant in the PAK2 gene.

CNVs and Chromosomal Aneuploidy in Patients With Early-Onset Schizophrenia and Bipolar Disorder: Genotype-Phenotype Associations.

Introduction: Early-onset schizophrenia (EOS) and bipolar disorder (EOB) start before the age of 18 years and have a more severe clinical course, a worse prognosis, and a greater genetic loading compared to the late-onset forms. Copy number variations (CNVs) are an important genetic factor in the etiology of psychiatric disorders. Therefore, this study aimed to analyze CNVs in patients with EOS and EOB and to establish genotype-phenotype relationships for contiguous gene syndromes or genes affected by identified CNVs.Methods: Molecular karyotyping was performed in 45 patients, 38 with EOS and seven with EOB hospitalized between 2010 and 2017. The exclusion criteria were medical or neurological disorders or IQ under 70. Detected CNVs were analyzed according to the standards and guidelines of the American College of Medical Genetics.Result: Molecular karyotyping showed CNVs in four patients with EOS (encompassing the PAK2, ADAMTS3, and ADAMTSL1 genes, and the 16p11.2 microduplication syndrome) and in two patients with EOB (encompassing the ARHGAP11B and PRODH genes). In one patient with EOB, a chromosomal aneuploidy 47, XYY was found.Discussion: Our study is the first study of CNVs in EOS and EOB patients in Slovenia. Our findings support the association of the PAK2, ARHGAP11B, and PRODH genes with schizophrenia and/or bipolar disorder. To our knowledge, this is also the first report of a multiplication of the ADAMTSL1 gene and the smallest deletion of the PAK2 gene in a patient with EOS, and one of the few reports of the 47, XYY karyotype in a patient with EOB.

RhoA/ROCKs signaling is increased by treatment with TKI-258 and leads to increased apoptosis in SCC-4 oral squamous cell carcinoma cell line.

This study evaluated the effect of treatment with TKI-258 on apoptosis, involving Rho GTPases and their effectors in SCC-4 cells of oral squamous cell carcinoma. Markers of cell death and apoptosis were analyzed in control and TKI-258-treated SCC-4 cells by flow cytometry. The involvement of Rho GTPases and effectors in the induction of apoptosis by TKI-258 was evaluated by quantification of cleaved PARP. Also, gene expression analysis of those proteins was performed. The treatment with TKI-258 led to a significant increase in cell death (7-AAD) and apoptosis (annexin V and cleaved PARP). When Rho GTPases were stimulated with LPA and inhibited with toxin A Clostridium difficile, the percentage of apoptotic cells increased and decreased, respectively. A similar effect was found when the treatment was with TKI-258 combined with LPA and toxin A. Treatment with TKI-258 significantly increased RhoA gene expression, while RhoB, RhoC, Rac1, and Cdc42 decreased significantly. ROCKs inhibitors (Y-27632 and HA-1077) reduced apoptosis compared with control. TKI-258 combined with Y-27632 or HA-1077 led to an increase in apoptosis compared with inhibitors only. Treatment with TKI-258 led to an increase in ROCK1 and ROCK2 gene expression, and a decrease in PAK1 and PAK2 gene expression. TKI-258 stimulates apoptosis in SCC-4 cells of oral squamous cell carcinoma. Possibly, RhoA GTPase and their effectors ROCKs participate in the signaling pathway inhibited by TKI-258. Therapies with multi-target inhibitors, such as TKI-258, may be promising alternatives for the clinical treatment of oral squamous cell carcinoma.

Early and Accurate Prediction of Postoperative Recurrence and Metastasis in Stage IIIB Gastric Cancer Patients by Combination of CEA, PAK5 and Circulating Tumor Cells

目的探讨CEA、PAK5联合循环肿瘤细胞(CTC)对ⅢB期胃癌患者术后复发转移的早期精准预测作用。 方法ELISA法、多重RNA/DNA原位分析法，对150例ⅢB期胃癌术后患者进行外周静脉血动态检测癌胚抗原(CEA)、PAK5、CTC及同时期影像学CT检查。对照组50例，实验组100例。实验组按CEA水平增高情况分为：CEA进行性增高组(实验A组, n=50)和无规律增高组(实验B组, n=50)。 结果单因素检测结果显示：CEA：按生物学进展时间(T2)：实验A组3~24月，中位时间13月; 实验B组4~32月，中位时间为22月。按影像进展时间(T3)：实验A组39例(78%)进展，出现时间5~8月，中位时间6.2月; 实验B组12例(24%)进展，出现时间4~15月，中位时间10.6月。51例影像学确诊进展的患者，T2时刻PAK5中表达范围为13.6%~83%，T3时刻PAK5高表达范围为37.8%~100%。CTC检测结果显示：当混合型+间质型/总细胞数比值> 30%时可预测生物学进展，混合型和间质型之和/总单细胞数比值> 50%和(或)间质型细胞数≥1可预测影像学CT进展。联合检测多因素结果显示：实验A组影像学进展39例患者CEA、PAK5、CTC阳性表达三者之间一致性在生物学进展时刻为82%;影像CT进展时刻为94%。 结论联合检测CEA、PAK5、CTC可作为早期预测ⅢB期胃癌术后复发转移的生物学指标。

MICRORNA IN MONITORING OF THE EVOLUTION OF GLIAL CEREBRAL TUMORS

Glial cerebral tumors (GCT) are primary tumors of the central nervous system that develop from glial tissue. Despite the use of combination treatment, the overall median survival rate in patients with glioblastoma, the most malignant form of HCC, is low. MicroRNA is a large class of endogenous small RNA molecules that inhibit mRNA translation of target genes involved in the evolution of GCT. It was shown that miRNA-21 has antiapoptotic and invasive functions by means of silencing of the PTEN tumor suppressor. MicroRNA-128 can activate a number of genes that are responsible for the mechanisms of suppression of tumor growth. MicroRNA-342, modulating PAK4 gene expression, is involved in the control of tumor cell proliferation, invasion and apoptosis.The aim of the work was to study the feasibility of using the assessment of miRNA-21, -128 and -342 expressions in the blood plasma and saliva of patients to monitor GCT progression or stabilization during combined modality treatment.Material and Methods. The main group consisted of 56 patients with GCTs. (34 men and 22 women), aged 25 to 72 years (average age 48.5 years) GCTs. The control group consisted of 50 people (45 volunteers and 5 neurosurgical patients with extracerebral meningiomas). The study of miRNA-21, -128, and -342 expressions was carried out according to the semiquantitative StemLoopRealTime protocol, using small U6 RNA as a reference gene. Data was processed using the STATISTICA for Windows computer system.Results. In 70 % of patients with disease progression assessed by magnetic resonance imaging, without progression in cerebral and focal neurological signs, the expression level of miRNA21 exceeded the control values both in blood plasma and saliva, and the expression levels of miRNA-128 and -342 were significantly reduced. In patients with GCT stabilization, the expression levels of miRNA-21, -128, and -342 did not go beyond the reference values. The diagnostic significance of miRNA-128, -342 for GCT was 69 %; therefore these miRNAs can be used in a clinical setting. Thus, the increased expression of miRNA-21 and decreased expressions of miRNA-128 and -342 in both blood plasma and saliva indicate cerebral glioma progression.

Novel PAK3 gene missense variant associated with two Chinese siblings with intellectual disability: a case report

BackgroundIntellectual disability (ID) constitutes the most common group of neurodevelopmental disorders. Exome sequencing has enabled the discovery of genetic mutations responsible for a wide range of ID disorders.Case presentationIn this study, we reported on two male siblings, aged 4 and 2 years, with motor and mental developmental delays and mild dysmorphic facial features. To identify the genetic causes of these symptoms, we employed trio-whole exome sequencing for the proband. We found a novel hemizygous missense variant in the PAK3 gene (c.1112G > A, p.Cys371Tyr), which encodes the p21-activated kinase 3, in the proband, which inherited from mother. The younger brother also has the hemizygous variant, which was confirmed by Sanger sequencing. The variant is located in the kinase domain and was regarded as a likely pathogenic variant in this family.ConclusionWe diagnosed two male siblings with developmental delays as having a PAK3 likely pathogenic variant. This finding expands the list of PAK3 gene mutations associated with neurodevelopmental disorders and provides further details on its clinical features.

The intellectual disability PAK3 R67C mutation impacts cognitive functions and adult hippocampal neurogenesis.

The link between mutations associated with intellectual disability (ID) and the mechanisms underlying cognitive dysfunctions remains largely unknown. Here, we focused on PAK3, a serine/threonine kinase whose gene mutations cause X-linked ID. We generated a new mutant mouse model bearing the missense R67C mutation of the Pak3 gene (Pak3-R67C), known to cause moderate to severe ID in humans without other clinical signs and investigated hippocampal-dependent memory and adult hippocampal neurogenesis. Adult male Pak3-R67C mice exhibited selective impairments in long-term spatial memory and pattern separation function, suggestive of altered hippocampal neurogenesis. A delayed non-matching to place paradigm testing memory flexibility and proactive interference, reported here as being adult neurogenesis-dependent, revealed a hypersensitivity to high interference in Pak3-R67C mice. Analyzing adult hippocampal neurogenesis in Pak3-R67C mice reveals no alteration in the first steps of adult neurogenesis, but an accelerated death of a population of adult-born neurons during the critical period of 18-28days after their birth. We then investigated the recruitment of hippocampal adult-born neurons after spatial memory recall. Post-recall activation of mature dentate granule cells in Pak3-R67C mice was unaffected, but a complete failure of activation of young DCX + newborn neurons was found, suggesting they were not recruited during the memory task. Decreased expression of the KCC2b chloride cotransporter and altered dendritic development indicate that young adult-born neurons are not fully functional in Pak3-R67C mice. We suggest that these defects in the dynamics and learning-associated recruitment of newborn hippocampal neurons may contribute to the selective cognitive deficits observed in this mouse model of ID.

Normal mammary gland development after MMTV-Cre mediated conditional PAK4 gene depletion

p21-activated kinases (PAKs) are serine/threonine kinases functioning as downstream effectors of the small GTPases Rac1 and Cdc42. Members of the PAK family are overexpressed in human breast cancer, but their role in mammary gland development is not fully explored. Here we examined the functional role of PAK4 in mammary gland development by creating a mouse model of MMTV-Cre driven conditional PAK4 gene depletion in the mammary gland. The PAK4 conditional knock-out mice were born healthy, with no observed developmental deficits. Mammary gland whole-mounts revealed no defects in ductal formation or elongation of the mammary tree through the fat pad. PAK4 gene depletion also did not alter proliferation and invasion of the mammary epithelium in young virgin mice. Moreover, adult mice gave birth to healthy pups with normal body weight upon weaning. This implies that MMTV-Cre induced gene depletion of PAK4 in mice does not impair normal mammary gland development and thereby provides an in vivo model that can be explored for examination of the potential function of PAK4 in breast cancer.

P21 protein-activated kinase 1 is associated with severe regressive autism, and epilepsy.

The p21-activated kinase (PAK) family of proteins function as key effectors of RHO family GTPases in mammalian cells to regulate many pathways including Ras/Raf/MEK/ERK and Wnt/β-catenin, amongst others. Here we report an individual with a novel autosomal dominant disorder characterized by severe regressive autism, intellectual disability, and epilepsy. Exome sequencing of the proband and her parents revealed a de novo variant in the PAK1 gene ([NM_001128620] c.362C>T/p.Pro121Leu). Studies in patient cells showed a clear effect on PAK1 protein function, including altered phosphorylation of targets (JNK and ERK), decreased abundance of β-catenin, and concomitant altered expression downstream of these key regulators. Our findings add PAK1 to the list of PAK proteins and kinases which when mutated cause rare genetic diseases.

PAK4 suppresses RELB to prevent senescence-like growth arrest in breast cancer

Overcoming cellular growth restriction, including the evasion of cellular senescence, is a hallmark of cancer. We report that PAK4 is overexpressed in all human breast cancer subtypes and associated with poor patient outcome. In mice, MMTV-PAK4 overexpression promotes spontaneous mammary cancer, while PAK4 gene depletion delays MMTV-PyMT driven tumors. Importantly, PAK4 prevents senescence-like growth arrest in breast cancer cells in vitro, in vivo and ex vivo, but is not needed in non-immortalized cells, while PAK4 overexpression in untransformed human mammary epithelial cells abrogates H-RAS-V12-induced senescence. Mechanistically, a PAK4 – RELB - C/EBPβ axis controls the senescence-like growth arrest and a PAK4 phosphorylation residue (RELB-Ser151) is critical for RELB-DNA interaction, transcriptional activity and expression of the senescence regulator C/EBPβ. These findings establish PAK4 as a promoter of breast cancer that can overcome oncogene-induced senescence and reveal a selective vulnerability of cancer to PAK4 inhibition.

Pak1 gene functioned differentially in different BCR-ABL subtypes in leukemiagenesis and treatment response through STAT5 pathway

The BCR-ABL fusion gene (BCR-ABL) has different subtypes such as p210 and p190 with p190 appear to lead to a worse prognosis. To explore the mechanism of difference in pathogenesis and prognosis in different BCR-ABL subtype-related leukemia, expression profile microarray analysis was conducted between p190 and p210 patients and verified by RT-PCR. The p21-activated kinase (PAK1) gene was chosen and regulation of the PAK1-STAT5 biological axis and its influence on proliferation and apoptosis in leukemia cells were also analyzed. The results showed that PAK1 might be an important molecular mechanism of the pathogenic difference between different BCR-ABL subtypes. In P210 (+) chronic myelogenous leukemia (CML), down-regulated PAK1 gene expressions may lead to the suppression of cell proliferation and promotion of apoptosis through phosphorylation of STAT5, with a reverse effect in P190 (+) acute lymphoblastic leukemia(ALL), especially acute B lymphoblastic leukemia (B-ALL). Additionally, in P210 (+) CML, down-regulated PAK1 expression may enhance the effect of TKI, whereas the reverse is true in P190 (+) B-ALL, demonstrating that PAK1 might also be an important therapeutic target between different BCR-ABL subtypes.