Molecular cloning, localization, and developmental expression of mouse brain finger protein (Bfp)/ZNF179: distribution of bfp mRNA partially coincides with the affected areas of Smith-Magenis syndrome

Purα regulates the induction of Znf179 transcription during neuronal differentiation

Development of the mammalian central nervous system is an important process, which is accomplished through precise regulations of many different genes. Zinc finger protein 179 (Znf179) is one of the essential genes that plays a critical role in neuronal differentiation. In our previous study, Znf179 knockout mice displayed brain malformation and impaired brain functions. We have also previously shown that Znf179 involves in cell cycle regulation, but the regulatory mechanism of Znf179 expression is not yet fully characterized. Herein, we identified that Purα is an essential factor for the promotor activity of Znf179. We also showed concurrent expression of Znf179 and Purα during neuronal differentiation. We also found that overexpression of Purα increased Znf179 expression in neuronal differentiated P19 cells. Through its direct binding to Znf179, as shown using DAPA, Purα upregulates Znf179 expression, suggesting that Purα is important for the regulation of Znf179 expression during neuronal differentiation. Our data indicated that Purα is involved in the transcriptional regulation of Znf179 gene during neuronal differentiation, and is indispensable during the brain development.

Neurolastin, a dynamin family GTPase, translocates to mitochondria upon neuronal stress and alters mitochondrial morphology in vivo

Neurolastin is a dynamin family GTPase that also contains a RING domain and exhibits both GTPase and E3 ligase activities. It is specifically expressed in the brain and is important for synaptic transmission, as neurolastin knockout animals have fewer dendritic spines and exhibit a reduction in functional synapses. Our initial study of neurolastin revealed that it is membrane-associated and partially co-localizes with endosomes. Using various biochemical and cell-culture approaches, we now show that neurolastin also localizes to mitochondria in HeLa cells, cultured neurons, and brain tissue. We found that the mitochondrial localization of neurolastin depends upon an N-terminal mitochondrial targeting sequence and that neurolastin is imported into the mitochondrial intermembrane space. Although neurolastin was only partially mitochondrially localized at steady state, it displayed increased translocation to mitochondria in response to neuronal stress and mitochondrial fragmentation. Interestingly, inactivation or deletion of neurolastin's RING domain also increased its mitochondrial localization. Using EM, we observed that neurolastin knockout animals have smaller but more numerous mitochondria in cerebellar Purkinje neurons, indicating that neurolastin regulates mitochondrial morphology. We conclude that the brain-specific dynamin GTPase neurolastin exhibits stress-responsive localization to mitochondria and is required for proper mitochondrial morphology.

Rnf112 deletion protects brain against intracerebral hemorrhage (ICH) in mice by inhibiting TLR-4/NF-κB pathway

Intracerebral hemorrhage (ICH) is reported as a common and often fatal type of stroke accompanied with high morbidity and mortality, and it frequently results in long-lasting neurological dysfunctions. However, the pathogenesis that contributes to ICH has not been fully understood. Rnf112, also known as Znf179, is a member of the RING finger protein family. The expression of Rnf112 is abundant in the brain and is modulated during brain progression and development. The study aimed to explore the role of Rnf112 in brain injury after ICH, as well as the underlying molecular mechanisms. The results indicated that ICH led to a significant decrease in Rnf112, which was confirmed in oxyhemoglobin (oxyHb)-incubated astrocytes and microglial cells. Moreover, the Rnf112 knockout (Rnf112^-/-) mice and wild type (WT) mice induced by ICH were further employed. Compared to the WT/ICH group, Rnf112^-/- mice exhibited accelerated brain injury, as evidenced by the increased brain water contents and neurological deficit scores (NDS). In comparison to WT/ICH group, a remarkable up-regulation in the release of pro-inflammatory cytokines, including tumor necrotic factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β, was observed in perihematoma tissues of Rnf112^-/- mice on day 3 post-ICH. The process was along with promoted glial fibrillary acidic protein (GFAP) and Iba1 expression and reduced NeuN levels. Furthermore, ICH-induced increases in toll-like receptor (TLR)-4 and myeloid differentiation primary response protein (MyD88) expression were exacerbated by the loss of Rnf112. The phosphorylated expression of IKKα, inhibitor of NF-κB (IκBα) and nuclear factor-kappa B (NF-κB) induced by ICH in perihematoma tissues of mice was markedly enhanced in Rnf112^-/- mice. Rnf112 repression-induced inflammatory response was verified in lipopolysaccharide (LPS)-incubated glial cells. In contrast, over-expressing Rnf112 markedly attenuated ICH-induced brain injury by restraining inflammation via inactivating TLR-4/NF-κB pathway. In summary, our findings suggested that Rnf112 expression was highly involved in the progression of ICH, and targeting Rnf112 signaling might be a promising therapeutic strategy against ICH development.

Znf179 E3 ligase-mediated TDP-43 polyubiquitination is involved in TDP-43- ubiquitinated inclusions (UBI) (+)-related neurodegenerative pathology

Background

The brain predominantly expressed RING finger protein, Znf179, is known to be important for embryonic neuronal differentiation during brain development. Downregulation of Znf179 has been observed in motor neurons of adult mouse models for amyotrophic lateral sclerosis (ALS), yet the molecular function of Znf179 in neurodegeneration has never been previously described. Znf179 contains the classical C3HC4 RING finger domain, and numerous proteins containing C3HC4 RING finger domain act as E3 ubiquitin ligases. Hence, we are interested to identify whether Znf179 possesses E3 ligase activity and its role in ALS neuropathy.

Methods

We used in vivo and in vitro ubiquitination assay to examine the E3 ligase autoubiquitination activity of Znf179 and its effect on 26S proteasome activity. To search for the candidate substrates of Znf179, we immunoprecipitated Znf179 and subjected to mass spectrometry (MS) analysis to identify its interacting proteins. We found that ALS/ FTLD-U (frontotemporal lobar degeneration (FTLD) with ubiquitin inclusions)-related neurodegenerative TDP-43 protein is the E3 ligase substrate of Znf179. To further clarify the role of E3 ubiquitin ligase Znf179 in neurodegenerative TDP-43-UBI (ubiquitinated inclusions) (+) proteinopathy, the effect of Znf179-mediated TDP-43 polyubiquitination on TDP-43 protein stability, aggregate formation and nucleus/cytoplasm mislocalization were evaluated in vitro cell culture system and in vivo animal model.

Results

Here we report that Znf179 is a RING E3 ubiquitin ligase which possesses autoubiquitination feature and regulates 26S proteasome activity through modulating the protein expression levels of 19S/20S proteasome subunits. Our immunoprecipitation assay and MS analysis results revealed that the neuropathological TDP-43 protein is one of its E3 ligase substrate. Znf179 interactes with TDP-43 protein and mediates polyubiquitination of TDP-43 in vitro and in vivo. In neurodegenerative TDP-43 proteinopathy, we found that Znf179-mediated polyubiquitination of TDP-43 accelerates its protein turnover rate and attenuates insoluble pathologic TDP-43 aggregates, while knockout of Znf179 in mouse brain results in accumulation of insoluble TDP-43 and cytosolic TDP-43 inclusions in cortex, hippocampus and midbrain regions.

Conclusions

Here we unveil the important role for the novel E3 ligase Znf179 in TDP-43-mediated neuropathy, and provide a potential therapeutic strategy for combating ALS/ FTLD-U neurodegenerative pathologies.

Electronic supplementary material

The online version of this article (10.1186/s12929-018-0479-4) contains supplementary material, which is available to authorized users.

Znf179 induces differentiation and growth arrest of human primary glioblastoma multiforme in a p53-dependent cell cycle pathway

Malignant glioblastoma multiforme (GBM) is an aggressive brain tumor with strong local invasive growth and a poor prognosis. One probable way to manipulate GBM cells toward a less invasive status is to reprogram the most malignant GBM cells to a more differentiated and less oncogenic phenotype. Herein, we identified a novel role of a RING finger protein Znf179 in gliomagenesis. Znf179 overexpression induced differentiation of primary GBM cells, which were accompanied with elevated glial fibrillary acidic protein (GFAP) expression through up-regulating several cell-cycle-related factors, p53, p21, and p27, and allowed the cell-cycle arrest in the G₀/G₁ phase. In addition, Znf179 was highly correlated with the prognosis and survival rates of glioma patients. The expression levels of Znf179 was relatively lower in glioma patients compared to normal people, and glioma patients with lower expression levels of Znf179 mRNA had poorer prognosis and lower survival rates. In conclusion, we provide novel insight that Znf179 can reprogram GBM cells into a more-differentiated phenotype and prevent the progression of gliomas to a more-malignant state through p53-mediated cell-cycle signaling pathways. Understanding the molecular mechanism of Znf179 in gliomagenesis could help predict prognostic consequences, and targeting Znf179 could be a potential biomarker for glioma progression.

Important Roles of Ring Finger Protein 112 in Embryonic Vascular Development and Brain Functions

Rnf112 is a member of the RING finger protein family. The expression of Rnf112 is abundant in the brain and is regulated during brain development. Our previous study has revealed that Rnf112 can promote neuronal differentiation by inhibiting the progression of the cell cycle in cell models. In this study, we further revealed the important functions of Rnf112 in embryo development and in adult brain. Our data showed that most of the Rnf112 ^-/- embryos exhibited blood vascular defects and died in utero. Upon further investigation, we found that the survival rate of homozygous Rnf112 knockout mice in 129/sv and C57BL/6 mixed genetic background was increased. The survived newborns of Rnf112 ^-/- mice manifested growth retardation as indicated by smaller size and a reduced weight. Although the overall organization of the brain did not appear to be severely affected in Rnf112 ^-/- mice, using in vivo 3D MRI imaging, we found that when compared to wild-type littermates, brains of Rnf112 ^-/- mice were smaller. In addition, Rnf112 ^-/- mice displayed impairment of brain functions including motor balance, and spatial learning and memory. Our results provide important aspects for the study of Rnf112 gene functions.

Neurolastin, a Dynamin Family GTPase, Regulates Excitatory Synapses and Spine Density

Membrane trafficking and spinogenesis contribute significantly to changes in synaptic strength during development and in various paradigms of synaptic plasticity. GTPases of the dynamin family are key players regulating membrane trafficking. Here, we identify a brain-specific dynamin family GTPase, neurolastin (RNF112/Znf179), with closest homology to atlastin. We demonstrate that neurolastin has functional GTPase and RING domains, making it a unique protein identified with this multi-enzymatic domain organization. We also show that neurolastin is a peripheral membrane protein that localizes to endosomes and affects endosomal membrane dynamics via its RING domain. In addition, neurolastin knockout mice have fewer dendritic spines, and rescue of the wild-type phenotype requires both the GTPase and RING domains. Furthermore, we find fewer functional synapses and reduced paired pulse facilitation in neurolastin knockout mice. Thus, we identify neurolastin as a dynamin family GTPase that affects endosome size and spine density.

Increase of zinc finger protein 179 in response to CCAAT/enhancer binding protein delta conferring an antiapoptotic effect in astrocytes of Alzheimer's disease

Reactive astrogliosis is a cellular manifestation of neuroinflammation and occurs in response to all forms and severities of the central nervous system (CNS)'s injury and disease. Both astroglial proliferation and antiapoptotic processes are aspects of astrogliosis. However, the underlying mechanism of this response remains poorly understood. In addition, little is known about why activated astrocytes are more resistant to stress and inflammation. CCAAT/enhancer binding protein delta (CEBPD) is a transcription factor found in activated astrocytes that surround β-amyloid plaques. In this study, we found that astrocytes activation was attenuated in the cortex and hippocampus of APPswe/PS1 E9 (AppTg)/Cebpd (-/-)mice. Furthermore, an increase in apoptotic astrocytes was observed in AppTg/Cebpd (-/-)mice, suggesting that CEBPD plays a functional role in enhancing the antiapoptotic ability of astrocytes. We found that Zinc Finger Protein 179 (ZNF179) was a CEBPD-regulated gene that played an antiapoptotic, but not proliferative, role in astrocytes. The transcriptions of the proapoptotic genes, insulin-like growth factor binding protein 3 (IGFBP3) and BCL2-interacting killer (BIK), were suppressed by ZNF179 via its interaction with the promyelocytic leukemia zinc finger (PLZF) protein in astrocytes. This study provides the first evidence that ZNF179, PLZF, IGFBP3, and BIK contributed to the novel CEBPD-induced antiapoptotic feature of astrocytes.

Analysis of the interaction between Zinc finger protein 179 (Znf179) and promyelocytic leukemia zinc finger (Plzf)

Background

Zinc finger protein 179 (Znf179), also known as ring finger protein 112 (Rnf112), is a member of the RING finger protein family and plays an important role in neuronal differentiation. To investigate novel mechanisms of Znf179 regulation and function, we performed a yeast two-hybrid screen to identify Znf179-interacting proteins.

Results

Using a yeast two-hybrid screen, we have identified promyelocytic leukemia zinc finger (Plzf) as a specific interacting protein of Znf179. Further analysis showed that the region containing the first two zinc fingers of Plzf is critical for its interaction with Znf179. Although the transcriptional regulatory activity of Plzf was not affected by Znf179 in the Gal4-dependent transcription assay system, the cellular localization of Znf179 was changed from cytoplasm to nucleus when Plzf was co-expressed. We also found that Znf179 interacted with Plzf and regulated Plzf protein expression.

Conclusions

Our results showed that Znf179 interacted with Plzf, resulting in its translocation from cytoplasm to the nucleus and increase of Plzf protein abundance. Although the precise nature and role of the Znf179-Plzf interaction remain to be elucidated, both of these two genes are involved in the regulation of neurogenesis. Our finding provides further research direction for studying the molecular functions of Znf179.

A novel RING finger protein, Znf179, modulates cell cycle exit and neuronal differentiation of P19 embryonal carcinoma cells

Znf179 is a member of the RING finger protein family. During embryogenesis, Znf179 is expressed in a restricted manner in the brain, suggesting a potential role in nervous system development. In this report, we show that the expression of Znf179 is upregulated during P19 cell neuronal differentiation. Inhibition of Znf179 expression by RNA interference significantly attenuated neuronal differentiation of P19 cells and a primary culture of cerebellar granule cells. Using a microarray approach and subsequent functional annotation analysis, we identified differentially expressed genes in Znf179-knockdown cells and found that several genes are involved in development, cellular growth, and cell cycle control. Flow cytometric analyses revealed that the population of G0/G1 cells decreased in Znf179-knockdown cells. In agreement with the flow cytometric data, the number of BrdU-incorporated cells significantly increased in Znf179-knockdown cells. Moreover, in Znf179-knockdown cells, p35, a neuronal-specific Cdk5 activator that is known to activate Cdk5 and may affect the cell cycle, and p27, a cell cycle inhibitor, also decreased. Collectively, these results show that induction of the Znf179 gene may be associated with p35 expression and p27 protein accumulation, which lead to cell cycle arrest in the G0/G1 phase, and is critical for neuronal differentiation of P19 cells.

Functional and genomic changes in the mouse ocular motor system in response to light deprivation from birth

Previous studies have suggested that abnormal visual experience early in life induces ocular motor abnormalities. The purpose of this study was to determine how visual deprivation alters the function and gene expression profile of the ocular motor system in mice. We measured the effect of dark rearing on eye movements, gene expression in the oculomotor nucleus, and contractility of isolated extraocular muscles. In vivo eye movement recordings showed decreased gains for optokinetic and vestibulo-ocular reflexes, confirming an effect of dark rearing on overall ocular motor function. Saccade peak velocities were preserved, however, arguing that the quantitative changes in these reflexes were not secondary to limitations in force generation. Using microarrays and quantitative PCR, we found that dark rearing shifted the oculomotor nucleus transcriptome to a state of delayed/arrested development. The expression of 132 genes was altered by dark rearing; these genes fit in various functional categories (signal transduction, transcription/translation control, metabolism, synaptic function, cytoskeleton), and some were known to be associated with neuronal development and plasticity. Extraocular muscle contractility was impaired by dark rearing to a greater extent than expected from the in vivo ocular motility studies: changes included decreased force and shortening speed and evidence of abnormal excitability. The results indicate that normal development of the mouse ocular motor system and its muscles requires visual experience. The transcriptional pattern of arrested development may indicate that vision is required to establish the adult pattern, but it also may represent the plastic response of oculomotor nuclei to abnormal extraocular muscles.

Non-syndromic mental retardation segregating with an apparently balanced t(1;17) reciprocal translocation through three generations

We describe a family in which non-syndromic mental retardation (MR) and an apparently balanced reciprocal translocation, t(1;17)(p36. 3;p11.2) segregates in eight individuals over three generations. Four children showed psychomotor developmental delay, reduced muscle tone, poor coordination, and learning difficulties. The affected adults had a varying range of behavioral problems and difficulties in social adjustment but no abnormal neurological signs. Most of them were functioning at the borderline learning difficulty level in intellectual abilities with additional specific difficulties in reading in two individuals. The Smith-Magenis and 1p36.3 deletion syndromes were excluded. We propose that this reciprocal translocation has disrupted an autosomal gene with an important function in cognitive development, and this family represents a unique resource for the molecular genetic study on non-syndromic MR.

Molecular cloning of ring finger protein 21 (RNF21)/interferon-responsive finger protein (ifp1), which possesses two RING-B box-coiled coil domains in tandem

We have cloned the full length of a novel cDNA, named ring finger protein 21 (RNF21), composed of the RING finger-B box-coiled coil (RBCC) domain and the B30.2 domain, which are characteristic of the RBCC-B30.2 family. As a structural feature, the RNF21 cDNA possessed at least three kinds of isoforms, due to alternative splicing, consisting of the long form with the RBCC-RBCC-B30.2 domain, the medium form with the RBCC-B30.2 domain, and the short form with only the RBCC domain. Moreover, respective transcripts corresponding to the three isoforms were detected in various human organs by reverse transcription-PCR and Northern blot analyses. Interestingly, the medium form of the RNF21 mRNA expressed most predominantly was dramatically up-regulated within 8-16 h by interferon stimulation of HeLa cells. These findings suggest that RNF21 is a downstream gene that may mediate interferon's biological action.

Molecular cloning of testis-abundant finger Protein/Ring finger protein 23 (RNF23), a novel RING-B box-coiled coil-B30.2 protein on the class I region of the human MHC

We have identified a genomic DNA fragment, using the PCR method with degenerate oligonucleotide primers which contain the conserved sequence of the RING finger domain. Using the DNA fragment as a probe, a novel cDNA was cloned from human and mouse testis. The cDNA had a domain structure of the typical RING-B box-coiled coil (RBCC)-B30.2 domain and therefore was named testis-abundant finger protein (tfp). Indeed, the transcript was highly expressed in the testis, although it was also found ubiquitously in various organs by Northern blot analysis. The tfp gene was mapped at the class I region of the human MHC (major histocompatibility complex), within which some known RBCC-B30.2 proteins such as RFP, RFB30/HERF1, AFP, and HZF had been localized. These findings demonstrate that several RBCC-B30.2 proteins including tfp, which are non-HLA proteins, are clustered within the class I region of the human MHC.

Underdeveloped uterus and reduced estrogen responsiveness in mice with disruption of the estrogen-responsive finger protein gene, which is a direct target of estrogen receptor alpha

The biological roles of estrogen-responsive finger protein (efp) in vivo were evaluated in mice carrying a loss-of-function mutation in efp by gene-targeted mutagenesis. Although efp homozygous mice were viable and fertile in both sexes, the uterus that expressed abundant estrogen receptor alpha exhibited significant underdevelopment. When the ovariectomized homozygotes were subjected to 17beta-estradiol treatment, they showed remarkably attenuated responses to estrogen, as exemplified by decreased interstitial water imbibition and retarded endometrial cell increase, at least, attributable to the lower ratio of G1 to S-phase progression in epithelial cells. These results suggest that efp is essential for the normal estrogen-induced cell proliferation and uterine swelling as one of the direct targets of estrogen receptor alpha.