Browsing by Author "Kara, Bulent"

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Biallelic loss of human CTNNA2, encoding alpha N-catenin, leads to ARP2/3 complex overactivity and disordered cortical neuronal migration
(NATURE PUBLISHING GROUP, 2018-01-01) Schaffer, Ashleigh E.; Breuss, Martin W.; Caglayan, Ahmet Okay; Al-Sanaa, Nouriya; Al-Abdulwahed, Hind Y.; Kaymakcalan, Hande; Yilmaz, Cahide; Zaki, Maha S.; Rosti, Rasim O.; Copeland, Brett; Baek, Seung Tae; Musaev, Damir; Scott, Eric C.; Ben-Omran, Tawfeg; Kariminejad, Ariana; Kayserili, Hulya; Mojahedi, Faezeh; Kara, Majdi; Cai, Na; Silhavy, Jennifer L.; Elsharif, Seham; Fenercioglu, Elif; Barshop, Bruce A.; Kara, Bulent; Wang, Rengang; Stanley, Valentina; James, Kiely N.; Nachnani, Rahul; Kalur, Aneesha; Megahed, Hisham; Incecik, Faruk; Danda, Sumita; Alanay, Yasemin; Faqeih, Eissa; Melikishvili, Gia; Mansour, Lobna; Miller, Ian; Sukhudyan, Biayna; Chelly, Jamel; Dobyns, William B.; Bilguvar, Kaya; Abou Jamra, Rami; Gunel, Murat; Gleeson, Joseph G.
Neuronal migration defects, including pachygyria, are among the most severe developmental brain defects in humans. Here, we identify biallelic truncating mutations in CTNNA2, encoding alpha N-catenin, in patients with a distinct recessive form of pachygyria. CTNNA2 was expressed in human cerebral cortex, and its loss in neurons led to defects in neurite stability and migration. The alpha N-catenin paralog, alpha E-catenin, acts as a switch regulating the balance between beta-catenin and Arp2/3 actin filament activities(1). Loss of alpha N-catenin did not affect beta-catenin signaling, but recombinant alpha N-catenin interacted with purified actin and repressed ARP2/3 actin-branching activity. The actin-binding domain of alpha N-catenin or ARP2/3 inhibitors rescued the neuronal phenotype associated with CTNNA2 loss, suggesting ARP2/3 de-repression as a potential disease mechanism. Our findings identify CTNNA2 as the first catenin family member with biallelic mutations in humans, causing a new pachygyria syndrome linked to actin regulation, and uncover a key factor involved in ARP2/3 repression in neurons.
SCREENING SLC2A1 GENE FOR SEQUENCE AND COPY NUMBER VARIATIONS ASSOCIATED WITH GLUT-1 DEFICIENCY SYNDROME
(ISTANBUL UNIV, FAC MEDICINE, PUBL OFF, 2020-01-01) Ornek Erguzeloglu, Cemre; Kara, Bulent; Karacan, Ilker; Ozdemir, Ozkan; Kesim, Yesim; Bebek, Nerses; Ozbek, Ugur; Ugur Iseri, Sibel Aylin
Objective: Glucose transporter-1 deficiency syndrome (GLUT1- DS) is defined as a metabolic encephalopathy that is associated with heterozygous and usually de novo pathogenic variations in the SLC2A1 (solute carrier family2 member1) gene. Materials and Methods: In this study, all coding exons and neighboring intronic regions of SLC2A1 were Sanger sequenced in 12 patients with clinically suspected GLUT1-DS. For de novo variations revealed after sequencing and segregation analysis, we also performed genome wide Single Nucleotide Polymor- phism (SNP) genotyping to confirm parental relatedness with the proband. In patients without any sequence variations, real-time quantitative real-time polymerase chain reaction (qPCR) was applied to determine the presence of any copy number variations (CNV). Results: Sanger sequencing followed by bioinformatics analysis, segregation in the family and SNP array genotyping revealed two novel and de novo pathogenic variations associated with the GLUT1-DS phenotype in 2 patients. qPCR results were compatible with one copy loss of SLC2A1 gene in another patient. All variations identified herein are likely to have caused null al-leles and resulted in GLUT1-DS through haplo insufficiency. Disscussion : In this study we used a series of molecular genetic approaches in order to identify all possible variations in SLC2A1 that may be associated with GLUT1-DS. This collective effort fa- cilitated diagnosis in 3 patients.