RESUMO
Retrotransposon control in mammals is an intricate process that is effectuated by a broad network of chromatin regulatory pathways. We previously discovered ChAHP, a protein complex with repressive activity against short interspersed element (SINE) retrotransposons that is composed of the transcription factor ADNP, chromatin remodeler CHD4, and HP1 proteins. Here we identify ChAHP2, a protein complex homologous to ChAHP, in which ADNP is replaced by ADNP2. ChAHP2 is predominantly targeted to endogenous retroviruses (ERVs) and long interspersed elements (LINEs) via HP1ß-mediated binding of H3K9 trimethylated histones. We further demonstrate that ChAHP also binds these elements in a manner mechanistically equivalent to that of ChAHP2 and distinct from DNA sequence-specific recruitment at SINEs. Genetic ablation of ADNP2 alleviates ERV and LINE1 repression, which is synthetically exacerbated by additional depletion of ADNP. Together, our results reveal that the ChAHP and ChAHP2 complexes function to control both nonautonomous and autonomous retrotransposons by complementary activities, further adding to the complexity of mammalian transposon control.
Assuntos
Retroelementos , Animais , Humanos , Camundongos , Homólogo 5 da Proteína Cromobox , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Cromossômicas não Histona/genética , Retrovirus Endógenos/genética , Regulação da Expressão Gênica/genética , Histonas/metabolismo , Histonas/genética , Elementos Nucleotídeos Longos e Dispersos/genética , Ligação Proteica , Retroelementos/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Complexos Multiproteicos/metabolismoRESUMO
Human mutations of ADNP and ADNP2 are known to be associated with neural developmental disorders (NDDs), including autism spectrum disorders (ASDs) and schizophrenia (SZ). However, the underlying mechanisms remain elusive. In this study, using CRISPR/Cas9 gene editing technology, we generated adnp and adnp2 mutant zebrafish models, which exhibited developmental delays, brain deficits, and core behavioral features of NDDs. RNA sequencing analysis of adnpa-/-; adnpb-/- and adnp2a-/-; adnp2b-/- larval brains revealed altered gene expression profiles affecting synaptic transmission, autophagy, apoptosis, microtubule dynamics, hormone signaling, and circadian rhythm regulation. Validation using whole-mount in situ hybridization (WISH) and real-time quantitative PCR (qRT-PCR) corroborated these findings, supporting the RNA-seq results. Additionally, loss of adnp and adnp2 resulted in significant downregulation of pan-neuronal HuC and neuronal fiber network α-Tubulin signals. Importantly, prolonged low-dose exposure to environmental endocrine disruptors (EEDs) aggravated behavioral abnormalities in adnp and adnp2 mutants. This comprehensive approach enhances our understanding of the complex interplay between genetic mutations and environmental factors in NDDs. Our findings provide novel insights and experimental foundations into the roles of adnp and adnp2 in neurodevelopment and behavioral regulation, offering a framework for future preclinical drug screening aimed at elucidating the pathogenesis of NDDs and related conditions.
Assuntos
Mutação , Proteínas do Tecido Nervoso , Proteínas de Peixe-Zebra , Peixe-Zebra , Animais , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Comportamento Animal/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/efeitos dos fármacos , Modelos Animais de Doenças , Disruptores Endócrinos/toxicidade , Transtorno do Espectro Autista/genética , Sistemas CRISPR-Cas , Interação Gene-Ambiente , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/induzido quimicamente , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismoRESUMO
Autophagy plays a key role in the pathophysiology of schizophrenia as manifested by a 40% decrease in BECN1/Beclin 1 mRNA in postmortem hippocampal tissues relative to controls. This decrease was coupled with the deregulation of the essential ADNP (activity-dependent neuroprotector homeobox), a binding partner of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 ß) another major constituent of autophagy. The drug candidate NAP (davunetide), a peptide fragment from ADNP, enhanced the ADNP-LC3B interaction. Parallel genetic studies have linked allelic variation in the gene encoding MAP6/STOP (microtubule-associated protein 6) to schizophrenia, along with altered MAP6/STOP protein expression in the schizophrenic brain and schizophrenic-like behaviors in Map6-deficient mice. In this study, for the first time, we reveal significant decreases in hippocampal Becn1 mRNA and reversal by NAP but not by the antipsychotic clozapine (CLZ) in Map6-deficient (Map6(+/-)) mice. Normalization of Becn1 expression by NAP was coupled with behavioral protection against hyperlocomotion and cognitive deficits measured in the object recognition test. CLZ reduced hyperlocomotion below control levels and did not significantly affect object recognition. The combination of CLZ and NAP resulted in normalized outcome behaviors. Phase II clinical studies have shown NAP-dependent augmentation of functional activities of daily living coupled with brain protection. The current studies provide a new mechanistic pathway and a novel avenue for drug development.