Deficiency of AP1 Complex Ap1g1 in Zebrafish Model Led to Perturbation of Neurodevelopment, Female and Male Fertility; New Insight to Understand Adaptinopathies.

In vertebrates, two homologous heterotetrameric AP1 complexes regulate the intracellular protein sorting via vesicles. AP-1 complexes are ubiquitously expressed and are composed of four different subunits: γ, ß1, µ1 and σ1. Two different complexes are present in eukaryotic cells, AP1G1 (contains γ1 subunit) and AP1G2 (contains γ2 subunit); both are indispensable for development. One additional tissue-specific isoform exists for µ1A, the polarized epithelial cells specific to µ1B; two additional tissue-specific isoforms exist for σ1A: σ1B and σ1C. Both AP1 complexes fulfil specific functions at the trans-Golgi network and endosomes. The use of different animal models demonstrated their crucial role in the development of multicellular organisms and the specification of neuronal and epithelial cells. Ap1g1 (γ1) knockout mice cease development at the blastocyst stage, while Ap1m1 (µ1A) knockouts cease during mid-organogenesis. A growing number of human diseases have been associated with mutations in genes encoding for the subunits of adaptor protein complexes. Recently, a new class of neurocutaneous and neurometabolic disorders affecting intracellular vesicular traffic have been referred to as adaptinopathies. To better understand the functional role of AP1G1 in adaptinopathies, we generated a zebrafish ap1g1 knockout using CRISPR/Cas9 genome editing. Zebrafish ap1g1 knockout embryos cease their development at the blastula stage. Interestingly, heterozygous females and males have reduced fertility and showed morphological alterations in the brain, gonads and intestinal epithelium. An analysis of mRNA profiles of different marker proteins and altered tissue morphologies revealed dysregulated cadherin-mediated cell adhesion. These data demonstrate that the zebrafish model organism enables us to study the molecular details of adaptinopathies and thus also develop treatment strategies.

Abnormal expression of NSF, α-SNAP and SNAP23 in pulmonary arterial hypertension in rats treated with monocrotaline.

BACKGROUND: Recent researches have shown that dysfunctional intracellular vesicular trafficking exists in pulmonary arterial hypertension (PAH). However, the expression of proteins involved in intracellular vesicular trafficking in pulmonary vasculature in PAH remains unclear. OBJECTIVE: To elucidate possible roles of proteins involved in intracellular vesicular trafficking in the development of PAH in rats treated with monocrotaline, changes in the expression of N-ethyl-maleimide-sensitive factor (NSF), α-soluble NSF attachment protein (α-SNAP) and synaptosome-associated membrane protein (SNAP) 23 were examined together with expression of caveolin-1 (cav-1), endogenous nitric oxide synthase (eNOS), type 2 bone morphogenetic receptor (BMPR2) and cellular apoptosis. METHODS: The mRNA expression was investigated by real time-PCR and protein expression by immunoblot method in rat lung. Caspase-3 was used as an indicator of cellular apoptosis and examined by immunoblot method. RESULTS: During the development of PAH, mRNA and protein expression of NSF, α-SNAP and SNAP23 all significantly increased before pulmonary arterial pressure started to increase, then all significantly decreased when PAH established. The expression of eNOS and BMPR2 changed similarly, while the mRNA and protein of cav-1 both downregulated after monocrotaline treatment. Caspase-3 was also increased after exposure to monocrotaline. CONCLUSIONS: Since the expression of NSF, α-SNAP and SNAP23 changed greatly during the onset of PAH and accompanied with abnormal expression of eNOS, BMPR2 and cav-1 and with enhanced cellular apoptosis, NSF, α-SNAP and SNAP23 appear to be associated with the development of PAH in rats treated with monocrotaline.

Viroporin activity of the JC polyomavirus is regulated by interactions with the adaptor protein complex 3.

Viroporins, which are encoded by a wide range of animal viruses, oligomerize in host cell membranes and form hydrophilic pores that can disrupt a number of physiological properties of the cell. Little is known about the relationship between host cell proteins and viroporin activity. The human JC polyomavirus (JCV) is the causative agent of progressive multifocal leukoencephalopathy. The JCV-encoded agnoprotein, which is essential for viral replication, has been shown to act as a viroporin. Here we demonstrate that the JCV agnoprotein specifically interacts with adaptor protein complex 3 through its δ subunit. This interaction interrupts adaptor protein complex 3-mediated vesicular trafficking with suppression of the targeting of the protein to the lysosomal degradation pathway and instead permits the transport of agnoprotein to the cell surface with resulting membrane permeabilization. The findings demonstrate a previously undescribed paradigm in virus-host interactions allowing the host to regulate viroporin activity and suggest that the viroporins of other viruses may also be highly regulated by specific interactions with host cell proteins.