Major brain malformations: corpus callosum dysgenesis, agenesis of septum pellucidum and polymicrogyria in patients with BCORL1-related disorders.

OBJECTIVE: BCORL1, a transcriptional co-repressor, has a role in cortical migration, neuronal differentiation, maturation, and cerebellar development. We describe BCORL1 as a new genetic cause for major brain malformations. METHODS AND RESULTS: We report three patients from two unrelated families with neonatal onset intractable epilepsy and profound global developmental delay. Brain MRI of two siblings from the first family depicted hypoplastic corpus callosum and septal agenesis (ASP) in the older brother and unilateral perisylvian polymicrogyria (PMG) in the younger one. MRI of the patient from the second family demonstrated complete agenesis of corpus callosum (CC). Whole Exome Sequencing revealed a novel hemizygous variant in NM_021946.5 (BCORL1):c.796C>T (p.Pro266Ser) in the two siblings from the first family and the NM_021946.5 (BCORL1): c.3376G>A; p.Asp1126Asn variant in the patient from the second family, both variants inherited from healthy mothers. We reviewed the patients' charts and MRIs and compared the phenotype to the other published BCORL1-related cases. Brain malformations have not been previously described in association with the BCORL1 phenotype. We discuss the potential influence of BCORL1 on brain development. CONCLUSIONS: We suggest that BCORL1 variants present with a spectrum of neurodevelopmental disorders and can lead to major brain malformations originating at different stages of fetal development. We suggest adding BCORL1 to the genetic causes of PMG, ASP, and CC dysgenesis.

Resolution of epileptic encephalopathy following treatment with transdermal nicotine.

We report resolution of an epileptic encephalopathy by administration of transdermal nicotine patches in an adolescent with severe nonlesional refractory frontal lobe epilepsy. The 18.5-year-old female patient had refractory epilepsy from the age of 11. Recurrent electroencephalography (EEG) recordings showed mostly generalized activity, albeit with right frontal predominance. Almost all antiepileptic medications failed to provide benefit. She developed an encephalopathic state with cognitive decline. The nonlesional frontal lobe epilepsy and a family history of a cousin with nocturnal epilepsy with frontal origin suggested genetic etiology. Transdermal nicotine patches brought complete resolution of the seizures, normalization of the EEG, and a significant improvement in her thinking process and speech organization. Sequencing of the CHRNB2 and CHRNA4 genes did not detect a mutation. Transdermal nicotine patches should be considered in severe pharmacoresistant frontal lobe epilepsy.

The abundant nuclear enzyme PARP participates in the life cycle of simian virus 40 and is stimulated by minor capsid protein VP3.

The abundant nuclear enzyme poly(ADP-ribose) polymerase (PARP) functions in DNA damage surveillance and repair and at the decision between apoptosis and necrosis. Here we show that PARP binds to simian virus 40 (SV40) capsid proteins VP1 and VP3. Furthermore, its enzymatic activity is stimulated by VP3 but not by VP1. Experiments with purified mutant proteins demonstrated that the PARP binding domain in VP3 is localized to the 35 carboxy-terminal amino acids, while a larger peptide of 49 amino acids was required for full stimulation of its activity. The addition of 3-aminobenzamide (3-AB), a known competitive inhibitor of PARP, demonstrated that PARP participates in the SV40 life cycle. The titer of SV40 propagated on CV-1 cells was reduced by 3-AB in a dose-dependent manner. Additional experiments showed that 3-AB did not affect viral DNA replication or capsid protein production. PARP did not modify the viral capsid proteins in in vitro poly(ADP-ribosylation) assays, implying that it does not affect SV40 infectivity. On the other hand, it greatly reduced the magnitude of the host cytopathic effects, a hallmark of SV40 infection. Additional experiments suggested that the stimulation of PARP activity by VP3 leads the infected cell to a necrotic pathway, characterized by the loss of membrane integrity, thus facilitating the release of mature SV40 virions from the cells. Our studies identified a novel function of the minor capsid protein VP3 in the recruitment of PARP for the SV40 lytic process.

Cellular transcription factor Sp1 recruits simian virus 40 capsid proteins to the viral packaging signal, ses.

Simian virus 40 (SV40) capsid assembly occurs in the nucleus. All three capsid proteins bind DNA nonspecifically, raising the dilemma of how they attain specificity to the SV40 minichromosome in the presence of a large excess of genomic DNA. The SV40 packaging signal, ses, which is required for assembly, is composed of multiple DNA elements that bind transcription factor Sp1. Our previous studies showed that Sp1 participates in SV40 assembly and that it cooperates in DNA binding with VP2/3. We hypothesized that Sp1 recruits the capsid proteins to the viral minichromosome, conferring upon them specific DNA recognition. Here, we have tested the hypothesis. Computer analysis showed that the combination of six tandem GC boxes at ses is not found at cellular promoters and therefore is unique to SV40. Cooperativity in DNA binding between Sp1 and VP2/3 was not abolished at even a 1,000-fold excess of cellular DNA, providing strong support for the recruitment hypothesis. Sp1 also binds VP1 and cooperates with VP1 in DNA binding. VP1 pentamers (VP1(5)) avidly interact with VP2/3, utilizing the same VP2/3 domain as described for polyomavirus. We conclude that VP1(5)-VP2/3 building blocks are recruited by Sp1 to ses, where they form the nucleation center for capsid assembly. By this mechanism the virus ensures that capsid formation is initiated at a single site around its minichromosome. Sp1 enhances the formation of SV40 pseudovirions in vitro, providing additional support for the model. Analyses of Sp1 and VP3 deletion mutants showed that Sp1 and VP2/3 bind one another and cooperate in DNA binding through their DNA-binding domains, with additional contacts outside these domains. VP1 contacts Sp1 at residues outside the Sp1 DNA-binding domain. These and additional data allowed us to propose a molecular model for the VP1(5)-VP2/3-DNA-Sp1 complex.