Identification of epidermal differentiation genes of the tuatara provides insights into the early evolution of lepidosaurian skin.

The tuatara (Sphenodon punctatus) is the phylogenetically closest relative of squamates (including lizards and snakes) from which it diverged around 250 million years ago. Together, they constitute the clade Lepidosauria. Fully terrestrial vertebrates (amniotes) form their skin barrier to the environment under the control of a gene cluster, termed the epidermal differentiation complex (EDC). Here we identified EDC genes in the genome of the tuatara and compared them to those of other amniotes. The organization of the EDC and proteins encoded by EDC genes are most similar in the tuatara and squamates. A subcluster of lepidosaurian EDC genes encodes corneous beta-proteins (CBPs) of which three different types are conserved in the tuatara. Small proline-rich proteins have undergone independent expansions in the tuatara and some, but not all subgroups of squamates. Two genes encoding S100 filaggrin-type proteins (SFTPs) are expressed during embryonic skin development of the tuatara whereas SFTP numbers vary between 1 and 3 in squamates. Our comparative analysis of the EDC in the tuatara genome suggests that many molecular features of the skin that were previously identified in squamates have evolved prior to their divergence from the lineage leading to the tuatara.

Bulked Segregant Analysis Coupled with Whole-Genome Sequencing (BSA-Seq) Mapping Identifies a Novel pi21 Haplotype Conferring Basal Resistance to Rice Blast Disease.

Basal or partial resistance has been considered race-non-specific and broad-spectrum. Therefore, the identification of genes or quantitative trait loci (QTLs) conferring basal resistance and germplasm containing them is of significance in breeding crops with durable resistance. In this study, we performed a bulked segregant analysis coupled with whole-genome sequencing (BSA-seq) to identify QTLs controlling basal resistance to blast disease in an F2 population derived from two rice varieties, 02428 and LiXinGeng (LXG), which differ significantly in basal resistance to rice blast. Four candidate QTLs, qBBR-4, qBBR-7, qBBR-8, and qBBR-11, were mapped on chromosomes 4, 7, 8, and 11, respectively. Allelic and genotypic association analyses identified a novel haplotype of the durable blast resistance gene pi21 carrying double deletions of 30 bp and 33 bp in 02428 (pi21-2428) as a candidate gene of qBBR-4. We further assessed haplotypes of Pi21 in 325 rice accessions, and identified 11 haplotypes among the accessions, of which eight were novel types. While the resistant pi21 gene was found only in japonica before, three Chinese indica varieties, ShuHui881, Yong4, and ZhengDa4Hao, were detected carrying the resistant pi21-2428 allele. The pi21-2428 allele and pi21-2428-containing rice germplasm, thus, provide valuable resources for breeding rice varieties, especially indica rice varieties, with durable resistance to blast disease. Our results also lay the foundation for further identification and functional characterization of the other three QTLs to better understand the molecular mechanisms underlying rice basal resistance to blast disease.

The pathogen Moniliophthora perniciosa promotes differential proteomic modulation of cacao genotypes with contrasting resistance to witches´ broom disease.

BACKGROUND: Witches' broom disease (WBD) of cacao (Theobroma cacao L.), caused by Moniliophthora perniciosa, is the most important limiting factor for the cacao production in Brazil. Hence, the development of cacao genotypes with durable resistance is the key challenge for control the disease. Proteomic methods are often used to study the interactions between hosts and pathogens, therefore helping classical plant breeding projects on the development of resistant genotypes. The present study compared the proteomic alterations between two cacao genotypes standard for WBD resistance and susceptibility, in response to M. perniciosa infection at 72 h and 45 days post-inoculation; respectively the very early stages of the biotrophic and necrotrophic stages of the cacao x M. perniciosa interaction. RESULTS: A total of 554 proteins were identified, being 246 in the susceptible Catongo and 308 in the resistant TSH1188 genotypes. The identified proteins were involved mainly in metabolism, energy, defense and oxidative stress. The resistant genotype showed more expressed proteins with more variability associated with stress and defense, while the susceptible genotype exhibited more repressed proteins. Among these proteins, stand out pathogenesis related proteins (PRs), oxidative stress regulation related proteins, and trypsin inhibitors. Interaction networks were predicted, and a complex protein-protein interaction was observed. Some proteins showed a high number of interactions, suggesting that those proteins may function as cross-talkers between these biological functions. CONCLUSIONS: We present the first study reporting the proteomic alterations of resistant and susceptible genotypes in the T. cacao x M. perniciosa pathosystem. The important altered proteins identified in the present study are related to key biologic functions in resistance, such as oxidative stress, especially in the resistant genotype TSH1188, that showed a strong mechanism of detoxification. Also, the positive regulation of defense and stress proteins were more evident in this genotype. Proteins with significant roles against fungal plant pathogens, such as chitinases, trypsin inhibitors and PR 5 were also identified, and they may be good resistance markers. Finally, important biological functions, such as stress and defense, photosynthesis, oxidative stress and carbohydrate metabolism were differentially impacted with M. perniciosa infection in each genotype.

PRPs localized to the middle lamellae are required for cortical tissue integrity in Medicago truncatula roots.

KEY MESSAGE: A family of repetitive proline-rich proteins interact with acidic pectins and play distinct roles in legume root cell walls affecting cortical and vascular structure. A proline-rich protein (PRP) family, composed of tandemly repeated Pro-Hyp-Val-X-Lys pentapeptide motifs, is found primarily in the Leguminosae. Four distinct size classes within this family are encoded by seven tightly linked genes: MtPRP1, MtPRP2 and MtPRP3, and four nearly identical MtPRP4 genes. Promoter fusions to ß-glucuronidase showed strong expression in the stele of hairy roots for all 4 PRP genes tested, with additional expression in the cortex for PRP1, PRP2 and PRP4. All except MtPRP4 are strongly expressed in non-tumorous roots, and secreted and ionically bound to root cell walls. These PRPs are absent from root epidermal cell walls, and PRP accumulation is highly localized within the walls of root cortical and vascular tissues. Within xylem tissue, PRPs are deposited in secondary thickenings where it is spatially exclusive to lignin. In newly differentiating xylem, PRPs are deposited in the regularly spaced paired-pits and pit membranes that hydraulically connect neighboring xylem elements. Hairpin-RNA knock-down constructs reducing PRP expression in Medicago truncatula hairy root tumors disrupted cortical and vascular patterning. Immunoblots showed that the knockdown tumors had potentially compensating increases in the non-targeted PRPs, all of which cross-react with the anti-PRP antibodies. However, PRP3 knockdown differed from knockdown of PRP1 and PRP2 in that it greatly reduced viability of hairy root tumors. We hypothesize that repetitive PRPs interact with acidic pectins to form block-copolymer gels that can play distinct roles in legume root cell walls.

Functional Comparison of Human and Zebra Fish FKBP52 Confirms the Importance of the Proline-Rich Loop for Regulation of Steroid Hormone Receptor Activity.

Previous studies demonstrated that the 52-kDa FK506-binding protein (FKBP52) proline-rich loop is functionally relevant in the regulation of steroid hormone receptor activity. While zebra fish (Danio rerio; Dr) FKBP52 contains all of the analogous domains and residues previously identified as critical for FKBP52 potentiation of receptor activity, it fails to potentiate activity. Thus, we used a cross-species comparative approach to assess the residues that are functionally critical for FKBP52 function. Random selection of gain-of-function DrFKBP52 mutants in Saccharomyces cerevisiae identified two critical residues, alanine 111 (A111) and threonine 157 (T157), for activation of receptor potentiation by DrFKBP52. In silico homology modeling suggests that alanine to valine substitution at position 111 in DrFKBP52 induces an open conformation of the proline-rich loop surface similar to that observed on human FKBP52, which may allow for sufficient surface area and increased hydrophobicity for interactions within the receptor-chaperone complex. A second mutation in the FKBP12-like domain 2 (FK2), threonine 157 to arginine (T157R), also enhanced potentiation, and the DrFKBP52-A111V/T157R double mutant potentiated receptor activity similar to human FKBP52. Collectively, these results confirm the functional importance of the FKBP52 proline-rich loop, suggest that an open conformation on the proline-rich loop surface is a predictor of activity, and highlight the importance of an additional residue within the FK2 domain.

Molecular Basis Underlying Host Immunity Subversion by Mycobacterium tuberculosis PE/PPE Family Molecules.

Mycobacterium tuberculosis proline-glutamic acid (PE)/proline-proline-glutamic acid (PPE) family proteins, with >160 members, are crucial for virulence, cell wall, host cell fate, host Th1/Th2 balance, and CD8+ T cell recognition. Ca2+ signaling is involved in PE/PPE protein-mediated host-pathogen interaction. PE/PPE proteins also function in heme utilization and nitric oxide production. PE/PPE family proteins are intensively pursued as diagnosis biomarkers and vaccine components.

Antimicrobial activities of a proline-rich proprotein from Spodoptera litura.

Antimicrobial peptides (AMPs) are produced by the stimulated humoral immune system. Most mature AMPs contain less than 50 amino acid residues. Some of them are generated from proproteins upon microbial challenges. Here, we report the antimicrobial activities of a proline-rich proprotein, named SlLebocin1 (SlLeb1), from the tobacco cutworm Spodoptera litura. SlLebocin1 cDNA contains a 477-bp open reading frame (ORF). It is mainly expressed in hemocytes and the midgut in naïve larvae. The transcript level was significantly induced in hemocytes but repressed in the midgut and fat body by bacterial challenges. The proprotein contains 158 amino acids with 3 RXXR motifs that are characteristic of some Lepidopteral lebocin proproteins. Four peptides corresponding to the predicted processed fragments were synthesized chemically, and their antimicrobial activities against two Gram-negative and two Gram-positive bacterial strains were analyzed. The peptides showed differential antimicrobial activities. For Escherichia coli and Bacillus subtilis, only the C-terminal fragment (124-158) showed strong inhibitory effects. For Staphylococcus aureus, all peptides showed partial inhibitions. None of them inhibited Serratia marcescens. Bacterial morphologies were examined by the scanning electron microscopy and confocal laser scanning microscopy. The antimicrobial peptides either disrupted cellular membrane or inhibited cell division and caused elongated/enlarged morphologies. The results may provide ideas for designing novel antibiotics.

De novo apparent loss-of-function mutations in PRR12 in three patients with intellectual disability and iris abnormalities.

PRR12 encodes a proline-rich protein nuclear factor suspected to be involved in neural development. Its nuclear expression in fetal brains and in the vision system supports its role in brain and eye development more specifically. However, its function and potential role in human disease has not been determined. Recently, a de novo t(10;19) (q22.3;q13.33) translocation disrupting the PRR12 gene was detected in a girl with intellectual disability and neuropsychiatric alterations. Here we report on three unrelated patients with heterozygous de novo apparent loss-of-function mutations in PRR12 detected by clinical whole exome sequencing: c.1918G>T (p.Glu640*), c.4502_4505delTGCC (p.Leu1501Argfs*146) and c.903_909dup (p.Pro304Thrfs*46). All three patients had global developmental delay, intellectual disability, eye and vision abnormalities, dysmorphic features, and neuropsychiatric problems. Eye abnormalities were consistent among the three patients and consisted of stellate iris pattern and iris coloboma. Additional variable clinical features included hypotonia, skeletal abnormalities, sleeping problems, and behavioral issues such as autism and anxiety. In summary, we propose that haploinsufficiency of PRR12 is associated with this novel multisystem neurodevelopmental disorder.

Insights into the evolution and domain structure of Ataxin-2 proteins across eukaryotes.

BACKGROUND: Ataxin-2 is an evolutionarily conserved protein first identified in humans as responsible for spinocerebellar ataxia type 2 (SCA2). The molecular basis of SCA2 is the expansion of a polyglutamine tract in Ataxin-2, encoding a Lsm domain that may bind RNA and a PAM2 motif that enables interaction with the poly (A) binding protein. Although the association with SCA2 has been verified, a detailed molecular function for Ataxin-2 has not been established. RESULTS: We have undertaken a survey of Ataxin-2 proteins across all eukaryotic domains. In eukaryotes, except for vertebrates and land plants, a single ortholog was identified. Notably, with the exception of birds, two Ataxin-2 genes exist in vertebrates. Expansion was observed in land plants and a novel class lacking the LsmAD domain was identified. Large polyQ tracts appear limited to primates and insects of the orders Hymenoptera and Diptera. A common feature across Ataxin-2 orthologs is the presence of proline-rich motifs, formerly described in the human protein. CONCLUSION: Our analysis provides valuable information on the evolution and domain structure of Ataxin-2 proteins. Proline-rich motifs that may mediate protein interactions are widespread in Ataxin-2 proteins, but expansion of polyglutamine tracts associated with spinocerebellar ataxia type 2, is present only in primates, as well as some insects. Our analysis of Ataxin-2 proteins provides also a source to examine orthologs in a number of different species.

Single nucleotide polymorphisms at the PRR3, ABCF1, and GNL1 genes in the HLA class I region are associated with Graves' ophthalmopathy in a gender-dependent manner.

OBJECTIVE: To investigate whether a conserved HLA class I region influenced the development of Graves' ophthalmopathy (GO) in patients with Graves' disease (GD) in a Taiwan-Chinese population. DESIGN: Case-control study. PARTICIPANTS: Four hundred sixty-eight Taiwan-Chinese patients with GD; 200 of these patients had GO, whereas 268 patients did not. METHODS: Five single nucleotide polymorphisms (SNPs) between the HLA-A and HLA-C loci were genotyped. MAIN OUTCOME MEASURES: The Mann-Whitney U test and chi-square test with Bonferroni correction were used. The odds ratios (ORs) were estimated by applying unconditional logistic regression with a 95% confidence intervals (CIs). RESULTS: Strong gender effects on the distribution of the SNPs were apparent: male GD patients carrying an A allele at rs2074503 in the PRR3 gene tended to avoid demonstrating GO (P = 0.008; OR, 0.450; 95% CI, 0.248-0.819), whereas female patients tended to show GO (P = 0.01; OR, 1.486; 95% CI, 1.098-2.012). In addition, only the female GD patients with a T allele at rs1264439 in the ABCF-1 gene tended to demonstrate GO (P = 0.005; OR, 1.539; 95% CI, 1.139-2.081). Analysis of the haplotype blocks of the SNPs rs2074505 (GNL1) and rs2074503 (PRR3) showed that haplotype HA1 was underrepresented in male GO patients (P = 0.004; OR, 0.418; 95% CI, 0.228-0.767), whereas HA-4 was underrepresented in female GO patients (P = 0.007; OR, 0.660; 95% CI, 0.490-0.895). CONCLUSIONS: The results suggested that SNPs at PRR3 and ABCF1 genes and the haplotype composed by SNPs at GNL1 and PRR3 between the HLA-A and HLA-C genes tended to predict GO in a gender-dependent manner in patients with GD in Taiwan.

Nck recruitment to the TCR required for ZAP70 activation during thymic development.

The adaptor protein Nck is inducibly recruited through its SH3.1 domain to a proline-rich sequence (PRS) in CD3ε after TCR engagement. However, experiments with a knockin mutant bearing an 8-aa replacement of the PRS have indicated that Nck binding to the TCR is constitutive, and that it promotes the degradation of the TCR in preselection double-positive (DP) CD4(+)CD8(+) thymocytes. To clarify these discrepancies, we have generated a new knockin mouse line (KI-PRS) bearing a conservative mutation in the PRS resulting from the replacement of the two central prolines. Thymocytes of KI-PRS mice are partly arrested at each step at which pre-TCR or TCR signaling is required. The mutation prevents the trigger-dependent inducible recruitment of endogenous Nck to the TCR but does not impair TCR degradation. However, KI-PRS preselection DP thymocytes show impaired tyrosine phosphorylation of CD3ζ, as well as impaired recruitment of ZAP70 to the TCR and impaired ZAP70 activation. Our results indicate that Nck is recruited to the TCR in an inducible manner in DP thymocytes, and that this recruitment is required for the activation of early TCR-dependent events. Differences in the extent of PRS mutation could explain the phenotypic differences in both knockin mice.

Activation of p53 following ionizing radiation, but not other stressors, is dependent on the proline-rich domain (PRD).

The tumor suppressor protein, p53 is one of the most important cellular defences against malignant transformation. In response to cellular stressors p53 can induce apoptosis, cell cycle arrest or senescence as well as aid in DNA repair. Which p53 function is required for tumor suppression is unclear. The proline-rich domain (PRD) of p53 (residues 58-101) has been reported to be essential for the induction of apoptosis. To determine the importance of the PRD in tumor suppression in vivo we previously generated a mouse containing a 33-amino-acid deletion (residues 55-88) in p53 (mΔpro). We showed that mΔpro mice are protected from T-cell tumors but not late-onset B-cell tumors. Here, we characterize the functionality of the PRD and show that it is important for mediating the p53 response to DNA damage induced by γ-radiation, but not the p53-mediated responses to Ha-Ras expression or oxidative stress. We conclude that the PRD is important for receiving incoming activating signals. Failure of PRD mutants to respond to the activating signaling produced by DNA damage leads to impaired downstream signaling, accumulation of mutations, which potentially leads to late-onset tumors.

PRR11 is a novel gene implicated in cell cycle progression and lung cancer.

Identification and functional analysis of novel potential cancer-associated genes is of great importance for developing diagnostic, preventive and therapeutic strategies for cancer treatment and management. In the present study, we isolated and identified a novel gene, proline-rich protein 11 (PRR11), implicated in both cell cycle progression and lung cancer. Our results showed that PRR11 was periodically expressed in a cell cycle-dependent manner, and RNAi-mediated silencing of PRR11 caused significant S phase arrest as well as growth retardation in HeLa cells. Moreover, PRR11 was overexpressed at both mRNA and protein levels in lung cancer tissues as compared with normal lung tissues. Large scale in silico analysis of clinical microarray datasets also indicated that high expression of PRR11 was significantly associated with poor prognosis in lung cancer patients. RNAi-mediated silencing of PRR11 caused S phase arrest, suppressed cellular proliferation, colony formation ability in lung cancer cells and inhibited tumorigenic potential in nude mice. Knockdown of PRR11 also inhibited cell migration and invasion ability in lung cancer cells. Furthermore, microarray analysis revealed that PRR11 knockdown caused the dysregulation of multiple critical pathways and various important genes involved in cell cycle, tumorigenesis and metastasis (e.g. CCNA1, RRM1, MAP4K4 and EPB41L3). Taken together, our results strongly demonstrated that this newly identified gene, PRR11, had a critical role in both cell cycle progression and tumorigenesis, and might serve as a novel potential target in the diagnosis and/or treatment of human lung cancer.

Deletion of the huntingtin proline-rich region does not significantly affect normal huntingtin function in mice.

The N-terminus of Huntingtin, the protein encoded by the Huntington's disease gene, contains a stretch of polyglutamine residues that is expanded in Huntington's disease. The polyglutamine stretch is flanked by two conserved protein domains in vertebrates: an N1-17 domain, and a proline-rich region (PRR). The PRR can modulate the structure of the adjacent polyglutamine stretch, and is a binding site for several interacting proteins. To determine the role of the PRR in Huntingtin function, we have generated a knock-in allele of the mouse Huntington's disease gene homolog that expresses full-length normal huntingtin lacking the PRR. Mice that are homozygous for the huntingtin PRR deletion are born at the normal Mendelian frequency, suggesting that the PRR is not required for essential huntingtin functions during embryonic development. Moreover, adult homozygous mutants did not exhibit any significant differences from wild-type controls in general motor function and motor learning. However, 18 month-old male, but not female, homozygous PRR deletion mutants exhibited deficits in the Morris water task, suggesting that age-dependent spatial learning and memory may be affected in a sex-specific fashion by the huntingtin PRR deletion.

Osteoblast-specific transcription factor Osterix (Osx) and HIF-1α cooperatively regulate gene expression of vascular endothelial growth factor (VEGF).

Bone formation is a highly regulated process involving the differentiation of mesenchymal stem cells to osteoblasts. Angiogenesis and osteogenesis are tightly coupled during bone formation. Vascular endothelial growth factor (VEGF) is involved in both processes. Relatively little is known about VEGF gene regulation in osteoblasts. Osterix (Osx) is a bone morphogenetic protein 2 (BMP-2) inducible osteoblast-specific transcription factor required for osteoblast differentiation and bone formation. Our recent study has demonstrated that Osx controls VEGF expression in osteoblasts. Here, we further characterized Osx regulation of VEGF. To address which domain of Osx is responsible for VEGF regulation, the deletion mutant analysis and transfection assay were carried out to show that proline-rich region (PRR) is required for Osx activation of VEGF promoter activity. Hypoxia-inducible factor-1α (HIF-1α) has been reported to couple angiogenesis to osteogenesis, and to upregulate VEGF. Effect of Osx on HIF-1α expression was examined in this study. Quantitative RT-PCR results revealed that HIF-1α remained unchanged between wild type and Osx knockout calvaria at E18.5 in mouse embryos. Overexpression of Osx in stable C2C12 mesenchymal cells using Tet-off system did not affect HIF-1α expression. HIF-1α level did not change after Osx inhibition by siRNA in osteoblasts. Moreover, BMP-2 stimulation led to upregulation of Osx and VEGF, but not HIF-1α. These results demonstrate that HIF-1α is not a downstream target of Osx in osteoblasts, suggesting that Osx regulation of VEGF is independent of HIF-1α expression level. Interestingly, synergistic interplays were observed between Osx and HIF-1α in VEGF promoter activation in transfection assay. Our findings indicate that Osx and HIF-1α cooperatively regulate VEGF expression.

A novel SNP of the PNRC1 gene and its association with reproductive traits in Tsaiya ducks.

Proline-rich nuclear receptor coactivator (PNRC)1 is a member of a new family of nuclear receptor coactivators capable of potentiating the transcriptional activity of nuclear receptors. The objective was to investigate the relationship between PNRC1 genotypes of single nucleotide polymorphism (SNP) and reproductive traits in ducks. Brown Tsaiya ducks (N = 305) from two lines, a control line with no selection and the selected line, were used. Polymerase chain reaction-single strand polymorphism and DNA sequencing were done to screen polymorphisms of the PNRC1 gene. A novel SNP (G98T) in 3'-untranslated region of the PNRC1 gene was identified and resulted in two genotypes, GG and GT. The frequencies of genotype GG and allele G were higher in both lines investigated. Regarding egg weight at first egg (EWFE), based on SNP trait association analysis, ducks with the GG genotype had a 4.48 g per egg greater egg weight at first egg when compared with ducks of the GT genotype in the control line (P < 0.05). In addition, this SNP was associated with the hatchability rate (HR) in the selected line; ducks with the GT genotype had a 6.70% higher hatchability rate than those with the GG genotype (P < 0.05). Therefore, we inferred that the PNRC1 gene could be a candidate locus or linked to a major gene that influenced egg weight-related and hatchability traits in Tsaiya ducks. Further investigations on additional duck populations with larger sample sizes are needed to confirm these results.

Binding of cellular p32 protein to the rubella virus P150 replicase protein via PxxPxR motifs.

A proline-rich region (PRR) within the rubella virus (RUBV) P150 replicase protein that contains three SH3 domain-binding motifs (PxxPxR) was investigated for its ability to bind cell proteins. Pull-down experiments using a glutathione S-transferase-PRR fusion revealed PxxPxR motif-specific binding with human p32 protein (gC1qR), which could be mediated by either of the first two motifs. This finding was of interest because p32 protein also binds to the RUBV capsid protein. Binding of p32 to P150 was confirmed and was abolished by mutation of the first two motifs. When mutations in the first two motifs were introduced into a RUBV cDNA infectious clone, virus replication was significantly impaired. However, virus RNA synthesis was found to be unaffected, and subsequent immunofluorescence analysis of RUBV-infected cells revealed co-localization of p32 and P150 but little overlap of p32 with RNA replication complexes, indicating that p32 does not participate directly in virus RNA synthesis. Thus, the role of p32 in RUBV replication remains unresolved.

A motif in the V3 domain of the kinase PKC-θ determines its localization in the immunological synapse and functions in T cells via association with CD28.

Protein kinase C-θ (PKC-θ) translocates to the center of the immunological synapse, but the underlying mechanism and its importance in T cell activation are unknown. Here we found that the V3 domain of PKC-θ was necessary and sufficient for localization to the immunological synapse mediated by association with the coreceptor CD28 and dependent on the kinase Lck. We identified a conserved proline-rich motif in V3 required for association with CD28 and immunological synapse localization. We found association with CD28 to be essential for PKC-θ-mediated downstream signaling and the differentiation of T helper type 2 cells (T(H)2 cells) and interleukin 17-producing helper T cells (T(H)17 cells) but not of T helper type 1 cells (T(H)1 cells). Ectopic expression of V3 sequestered PKC-θ from the immunological synapse and interfered with its functions. Our results identify a unique mode of CD28 signaling, establish a molecular basis for the immunological synapse localization of PKC-θ and indicate V3-based 'decoys' may be therapeutic modalities for T cell-mediated inflammatory diseases.

Deletion of the proline-rich region of the murine metastasis susceptibility gene Brd4 promotes epithelial-to-mesenchymal transition- and stem cell-like conversion.

The bromodomain-containing chromatin-modifying factor BRD4 is an inherited susceptibility gene for breast cancer progression and metastasis, but its functionality in these settings has yet to be explored. Here we show that deletion of either of the BRD4 bromodomains had modest effects on the metastatic suppression ability of BRD4. In contrast, expression of the natural short isoform of BRD4 that truncates the protein after the SEED domain restored progression and metastatic capacity. Unexpectedly, deletion of the proline-rich region induced mesenchymal-like conversion and acquisition of cancer stem cell-like properties, which are mediated by the carboxy-terminal P-TEFb binding domain. Deletion of this proline-rich region also induced a gene expression signature that predicted poor outcome in human breast cancer data sets and that overlapped G3 grade human breast tumors. Thus our findings suggest that BRD4 may be altering the predisposition of tumors to undergo conversion to a more de-differentiated or primitive state during metastatic progression.

The proline/arginine-rich domain is a major determinant of dynamin self-activation.

Dynamins induce membrane vesiculation during endocytosis and Golgi budding in a process that requires assembly-dependent GTPase activation. Brain-specific dynamin 1 has a weaker propensity to self-assemble and self-activate than ubiquitously expressed dynamin 2. Here we show that dynamin 3, which has important functions in neuronal synapses, shares the self-assembly and GTPase activation characteristics of dynamin 2. Analysis of dynamin hybrids and of dynamin 1-dynamin 2 and dynamin 1-dynamin 3 heteropolymers reveals that concentration-dependent GTPase activation is suppressed by the C-terminal proline/arginine-rich domain of dynamin 1. Dynamin proline/arginine-rich domains also mediate interactions with SH3 domain-containing proteins and thus regulate both self-association and heteroassociation of dynamins.