Midfacial Toddler Excoriation syndrome (MiTES): case series, diagnostic criteria and evidence for a pathogenic mechanism

BACKGROUND

PRDM12 polyalanine tract expansions cause two different disorders; Midfacial Toddler Excoriation Syndrome (MiTES) - itch with normal pain sensation associated with homozygous 18 alanines (18A), and congenital insensitivity to pain (CIP) with normal itch with homozygous 19A. Knowledge of the phenotype, genotype, and disease mechanism of MiTES is incomplete. Why PRDM12 18A versus 19A can cause almost opposite phenotypes is unknown; no other poly-alanine or poly-glutamine tract expansion disease causes two such disparate phenotypes.

METHODS

We assessed the genotype and phenotype of 9 new, 9 atypical, and 6 previously reported patients diagnosed with MiTES. Using cell lines with homozygous PRDM12 of 12A (normal), 18A (MiTES) and 19A (CIP) we examined PRDM12 aggregation and subcellular localisation by image separation confocal microscopy and sub-cellular fractionation western blotting.

RESULTS

MiTES presents in the first year of life, and in all cases the condition regresses over the first decade leaving scarring. The MiTES phenotype is highly distinctive. Features overlapping with PRDM12-CIP are rarely found. The genotype-phenotype study of PRDM12 polyalanine tract shows that 7A -15A are normal; 16A -18A are associated with MiTES; 19A leads to CIP; and no clinically atypical MiTES cases had an expansion. PRDM12 aggregation and sub-cellular localisation differ significantly between 18A and normal 12A cell lines and between 18A and 19A cell lines. MiTES is a new protein aggregation disease.

CONCLUSION

We provide diagnostic criteria for MiTES, and improved longitudinal data. MiTES and CIP are distinct phenotypes despite their genotypes varying by a single alanine in the PRDM12 polyalanine tract. We found clear distinctions between the cellular phenotypes of normal, MiTES and CIP cells.. We hypothesise that the developmental environment of the trigeminal ganglion is unique and critically sensitive to prenatal and postnatal levels of PRDM12.

Evidence of a genetic background predisposing to complex regional pain syndrome type 1

BACKGROUND

Complex regional pain syndrome type 1 (CRPS-1) is a rare, disabling and sometimes chronic disorder usually arising after a trauma. This exploratory study examined whether patients with chronic CRPS-1 have a different genetic profile compared with those who do not have the condition.

METHODS

Exome sequencing was performed to seek altered non-synonymous SNP allele frequencies in a discovery cohort of well-characterised patients with chronic CRPS-1 (n=34) compared with population databases. Identified SNP alleles were confirmed by Sanger sequencing and sought in a replication cohort (n=50). Gene expression of peripheral blood macrophages was assessed.

RESULTS

In the discovery cohort, the rare allele frequencies of four non-synonymous SNPs were statistically increased. The replication cohort confirmed this finding. In a chronic pain cohort, these alleles were not overexpressed. In total, 25 out of 84 (29.8%) patients with CRPS-1 expressed a rare allele. The SNPs were rs41289586 in ANO10, rs28360457 in P2RX7, rs1126930 in PRKAG1 and rs80308281 in SLC12A9. Males were more likely than females to have a rare SNP allele, 8 out of 14 (57.1%) vs 17 out of 70 (24.3%) (Fisher's p=0.023). ANO10, P2RX7, PRKAG1 and SLC12A9 were all expressed in macrophages from healthy human controls.

CONCLUSION

A single SNP in each of the genes ANO10, P2RX7, PRKAG1 and SLC12A9 was associated with developing chronic CRPS-1, with more males than females expressing these rare alleles. Our work suggests the possibility that a permissive genetic background is an important factor in the development of CRPS-1.

Phenotypic manifestation of α-synuclein strains derived from Parkinson's disease and multiple system atrophy in human dopaminergic neurons

α-Synuclein is critical in the pathogenesis of Parkinson's disease and related disorders, yet it remains unclear how its aggregation causes degeneration of human dopaminergic neurons. In this study, we induced α-synuclein aggregation in human iPSC-derived dopaminergic neurons using fibrils generated de novo or amplified in the presence of brain homogenates from Parkinson's disease or multiple system atrophy. Increased α-synuclein monomer levels promote seeded aggregation in a dose and time-dependent manner, which is associated with a further increase in α-synuclein gene expression. Progressive neuronal death is observed with brain-amplified fibrils and reversed by reduction of intraneuronal α-synuclein abundance. We identified 56 proteins differentially interacting with aggregates triggered by brain-amplified fibrils, including evasion of Parkinson's disease-associated deglycase DJ-1. Knockout of DJ-1 in iPSC-derived dopaminergic neurons enhance fibril-induced aggregation and neuronal death. Taken together, our results show that the toxicity of α-synuclein strains depends on aggregate burden, which is determined by monomer levels and conformation which dictates differential interactomes. Our study demonstrates how Parkinson's disease-associated genes influence the phenotypic manifestation of strains in human neurons.

A third HSAN5 mutation disrupts the nerve growth factor furin cleavage site

Bi-allelic dysfunctional mutations in nerve growth factor (NGF) cause the rare human phenotype hereditary sensory and autonomic neuropathy type 5 (HSAN5). We describe a novel NGF mutation in an individual with typical HSAN5 findings. The mutation c.361C>T, p.R121W is at the last residue of the furin cleavage motif Arg-Ser-Lys-Arg in proNGF. We show that the p.R121W mutation completely abolishes the formation of mature NGF-β. Surprisingly, mutant p.R121W cells produced very little proNGF. Instead, the two progressive cleavage products of proNGF were produced, proA-NGF and proB-NGF, with proB-NGF being the predominant NGF-derived peptide and the only peptide secreted by mutant p.R121W cells. We found that the ability of the p.R121W mutation to cause tropomyosin receptor kinase A autophosphorylation and mitogen-activated protein kinase phosphorylation was significantly reduced compared to controls (p < 0.05 and p < 0.01). By studying the PC12 cell line morphology and neurite length over a week, we found the p.R121W mutation had residual, but much reduced, neurotrophic activity when compared to wild-type NGF. Finally, we assessed whether the p.R121W mutation affected apoptosis and found a reduced protective effect compared to wild-type NGF. Our results suggest that the p.R121W NGF mutation causes HSAN5 through negating the ability of furin to cleave proNGF to produce NGF-β.

Stenotrophomonas sp. RZS 7, a novel PHB degrader isolated from plastic contaminated soil in Shahada, Maharashtra, Western India

This paper reports an isolation and identification of novel poly-β-hydroxybutyrate (PHB) degrading bacterium Stenotrophomonas sp. RZS 7 and studies on its extracellular PHB degrading depolymerase enzyme. The bacterium isolated from soil samples of plastic contaminated sites of municipal area in Shahada, Maharashtra, Western India. It was identified as Stenotrophomonas sp. RZS 7 based on polyphasic approach. The bacterium grew well in minimal salt medium (MSM) and produced a zone (4.2 mm) of PHB hydrolysis on MSM containing PHB as the only source of nutrient. An optimum yield of enzyme was obtained on the fifth day of incubation at 37 °C and at pH 6.0. Further increase in enzyme production was recorded with Ca²⁺ ions, while other metal ions like Fe²⁺ (1 mM) and chemical viz. mercaptoethanol severally affected the production of enzyme.

A Comprehensive Functional Analysis of NTRK1 Missense Mutations Causing Hereditary Sensory and Autonomic Neuropathy Type IV (HSAN IV)

Hereditary sensory and autonomic neuropathy type IV (HSAN IV) is an autosomal recessive disorder characterized by a complete lack of pain perception and anhidrosis. Here, we studied a cohort of seven patients with HSAN IV and describe a comprehensive functional analysis of seven novel NTRK1 missense mutations, c.1550G >A, c.1565G >A, c.1970T >C, c.2096T >C, c.2254T >A, c.2288G >C, and c.2311C >T, corresponding to p.G517E, p.G522E, p.L657P, p.I699T, p.C752S, p.C763S, and p.R771C, all of which were predicted pathogenic by in silico analysis. The results allowed us to assess the pathogenicity of each mutation and to gain novel insights into tropomyosin receptor kinase A (TRKA) downstream signaling. Each mutation was systematically analyzed for TRKA glycosylation states, intracellular and cell membrane expression patterns, nerve growth factor stimulated TRKA autophosphorylation, TRKA-Y496 phosphorylation, PLCγ activity, and neurite outgrowth. We showed a diverse range of functional effects: one mutation appeared fully functional, another had partial activity in all assays, one mutation affected only the PLCγ pathway and four mutations were proved null in all assays. Thus, we conclude that complete abolition of TRKA kinase activity is not the only pathogenic mechanism underlying HSAN IV. By corollary, the assessment of the clinical pathogenicity of HSAN IV mutations is more complex than initially predicted and requires a multifaceted approach.

Dynamism of PGPR in bioremediation and plant growth promotion in heavy metal contaminated soil

Heavy metal contamination, particularly of cultivable lands, is a matter of concern. Bioremediation helps in reversing such contamination to certain extent. Here, we report isolation, polyphasic identification and the role of siderophore producing rhizobacteria Alcaligenes feacalis RZS2 and Pseudomonas aeruginosa RZS3 in bioremediation of heavy metal contaminated soil and plant growth promotion activity in such contaminated soil. Siderophore produced by A. feacalis RZS2 and P. aeruginosa RZS3 strains chelated various heavy metal ions like MnCl₂.4H₂O, NiCl₂.6H₂O, ZnCl₂, CuCl₂ and CoCl₂ other than FeCl₃.6H2O at batch scale. Their bioremediation potential was superior over the chemical ion chelators like EDTA and citric acid. These isolates also promoted growth of wheat and peanut seeds sown in heavy metal contaminated soil. Effective root colonizing ability of these isolates was observed in wheat and peanut plants.

A novel disorder reveals clathrin heavy chain-22 is essential for human pain and touch development

Congenital inability to feel pain is very rare but the identification of causative genes has yielded significant insights into pain pathways and also novel targets for pain treatment. We report a novel recessive disorder characterized by congenital insensitivity to pain, inability to feel touch, and cognitive delay. Affected individuals harboured a homozygous missense mutation in CLTCL1 encoding the CHC22 clathrin heavy chain, p.E330K, which we demonstrate to have a functional effect on the protein. We found that CLTCL1 is significantly upregulated in the developing human brain, displaying an expression pattern suggestive of an early neurodevelopmental role. Guided by the disease phenotype, we investigated the role of CHC22 in two human neural crest differentiation systems; human induced pluripotent stem cell-derived nociceptors and TRKB-dependant SH-SY5Y cells. In both there was a significant downregulation of CHC22 upon the onset of neural differentiation. Furthermore, knockdown of CHC22 induced neurite outgrowth in neural precursor cells, which was rescued by stable overexpression of small interfering RNA-resistant CHC22, but not by mutant CHC22. Similarly, overexpression of wild-type, but not mutant, CHC22 blocked neurite outgrowth in cells treated with retinoic acid. These results reveal an essential and non-redundant role for CHC22 in neural crest development and in the genesis of pain and touch sensing neurons.

Transcriptional regulator PRDM12 is essential for human pain perception

Pain perception has evolved as a warning mechanism to alert organisms to tissue damage and dangerous environments. In humans, however, undesirable, excessive or chronic pain is a common and major societal burden for which available medical treatments are currently suboptimal. New therapeutic options have recently been derived from studies of individuals with congenital insensitivity to pain (CIP). Here we identified 10 different homozygous mutations in PRDM12 (encoding PRDI-BF1 and RIZ homology domain-containing protein 12) in subjects with CIP from 11 families. Prdm proteins are a family of epigenetic regulators that control neural specification and neurogenesis. We determined that Prdm12 is expressed in nociceptors and their progenitors and participates in the development of sensory neurons in Xenopus embryos. Moreover, CIP-associated mutants abrogate the histone-modifying potential associated with wild-type Prdm12. Prdm12 emerges as a key factor in the orchestration of sensory neurogenesis and may hold promise as a target for new pain therapeutics.

Plant growth promotion and root colonization by EPS producing Enterobacter sp. RZS5 under heavy metal contaminated soil

The heavy metal resistant bacterium isolated from field soil and identified as Enterobacter sp. RZS5 tolerates a high concentration (100-2000 μM) of various heavy metal ions such as Mn2+, Ni2+, Zn2+, Cu2+, CO2+ and Fe2+ when grown in such environment and produces exopolysaccharides (EPS). Here, we have demonstrated EPS production by Enterobacter sp. RZS5 during 60 h of growth in yeast extract mannitol broth (YEMB). The yield increased by two fold after the addition of 60 μM of Ca2+; 50 μM of Fe2+ and 60 μM of Mg2+ ions in YEMB, and the optimization of physico-chemical parameters. EPS was extracted with 30% (v/v) of isopropanol as against the commonly used 50% (v/v) isopropanol method. EPS-rich broth promoted seed germination, shoot height, root length, number of leaves and chlorophyll content of wheat (Triticum aestivum) seed and peanut (Arachis hypogaea) seed. The higher colony-forming unit of Enterobacter sp. in soil inoculated with EPS rich broth of Enterobacter sp. indicated the root colonizing potential and rhizosphere competence of the isolate. The FTIR spectra of the EPS extract confirmed the presence of the functional group characteristics of EPS known to exhibit a high binding affinity towards certain metal ions. This overall growth and vigour in plants along with the effective root colonization, reflected the potential of the isolate as an efficient bio-inoculant in bioremediation.

Production of biocontrol traits by banana field fluorescent Pseudomonads and comparison with chemical fungicide

Pseudomonas aeruginosa isolated from banana field rhizosphere produced different antifungal metabolites like bactriocin, hydrogen cyanide and siderophore. Bacteriocinogenic, siderophoregenic, and HCN rich broth of isolate inhibited the growth of phytopathogen like Aspergilus niger, Aspergilus flavus, Fusarium oxysporum and Alternaria alternata. The isolate exhibited more antifungal activity and comparatively low MIC vis-a-vis commonly used copper based systemic chemical fungicide;bil cop.

Purification of alpha-glucosidae and invertase from bakers' yeast on modified polymeric supports

In the present work Amberlite XAD-16 and Indion NPA-1, Polystyrene Divinylbenzene macroreticular spherical resins, have been evaluated quantitatively as supports for the adsorption and isolation of the yeast proteins and the enzymes, invertase and alpha-glucosidase. Modification of these supports has been carried out by surface grafting using acrylate polymers to reduce the hydrophobicity and nonspecific adsorption of proteins. Good grafting efficiency, in excess of 90%, has been obtained using ultrasonic irradiation for the surface activation of polystyrene resins. XAD-16 has higher adsorption capacities for the total yeast proteins as well as for both the enzymes, alpha-glucosidase and invertase, than NPA-1 in its respective native and grafted form. Adsorption capacities of XAD-16 and NPA-1 in their respective native and grafted forms for alpha-glucosidase are higher than the capacities for invertase. Nonspecific adsorption of total proteins has been reduced considerably after the grafting of acrylate polymers on hydrophobic supports. At the same time selectivity for the adsorption of both the enzymes has been enhanced on grafted supports. The overall solid-liquid adsorption mass transfer coefficient values (Kla) estimated for adsorption of invertase on XAD are lower than those for alpha-glucosidase. Native and grafted resins could be regenerated and reused for adsorption of alpha-glucosidase for two regeneration cycles studied. Storage stability of invertase and alpha-glucosidase is the same on native and grafted form of XAD-16 and is more than the enzymes in the free form.

Open lung biopsy for diffuse infiltrative lung disease

The purpose of this study was to determine the most appropriate site of biopsy in patients with diffuse infiltrative lung disease (DILD). Twenty patients were evaluated. During open lung biopsy, a representative region (inflamed and least fibrotic) of the radiographically most involved lobe was identified and a biopsy done. A second biopsy specimen was obtained from an adjacent accessible lobe. The biopsy specimen from each lobe was processed separately, and a descriptive histologic report was generated for each of the two lobes. Tissue was cultured for bacteria, fungi, and mycobacteria. In 17 patients, the second biopsy site had fewer roentgenographic abnormalities than the radiographically most involved lobe. In 3 patients, the number of radiographic abnormalities was equal in all lobes. The same pathologic diagnosis was reached by histologic examination of the two biopsy specimens in 8 of 10 patients with acute DILD and in 10 of 10 patients with chronic DILD. In 2 patients, the biopsy specimen from the radiographically most involved lobe showed pathologic features not seen in the other specimen. Cultures from both biopsy specimens were grown separately in 6 patients. Fungi (n = 2) and bacteria (n = 1) were isolated from the radiographically most involved lobe (n = 2) or from the lobe of initial lung infiltration (n = 1) in 3 patients. When biopsy specimens are obtained from a representative region of the radiographically most involved lobe in patients with DILD, biopsy of other lobes is unnecessary.

Defective brain microtubule assembly in Alzheimer's disease

Brains obtained within 2-4 hours post mortem and histopathologically confirmed for Alzheimer's disease and non-Alzheimer brains from age-matched controls were examined for in-vitro assembly of microtubules and neurofilaments. Microtubule assembly was observed only in control but not in Alzheimer brains, and neurofilaments were obtained from both types of brain. The microtubule-associated protein tau, which stimulates assembly of microtubules from tubulin, was abnormally phosphorylated in Alzheimer but not in control brain microtubule preparations. Alzheimer brains did not show the presence of any inhibitor of microtubule assembly or any abnormality of tubulin. DEAE-dextran, a polycation which mimics tau in stimulating microtubule assembly, induced the assembly of microtubules in Alzheimer brain. Tubulin from both normal and Alzheimer brains was labelled on western blots by a monoclonal antibody to the tyrosinylated carboxy-terminal epitope of alpha tubulin. These studies suggest that in Alzheimer's disease tubulin can be assembled into brain microtubules, but the process is defective, probably because of abnormal phosphorylation of tau. This post-translational alteration of tau might be the cause of the neurofibrillary abnormality in Alzheimer's disease.