Uncovering the essential roles of glutamate carboxypeptidase 2 orthologs in Caenorhabditis elegans

Human glutamate carboxypeptidase 2 (GCP2) from the M28B metalloprotease group is an important target for therapy in neurological disorders and an established tumor marker. However, its physiological functions remain unclear. To better understand general roles, we used the model organism Caenorhabditis elegans to genetically manipulate its three existing orthologous genes and evaluate the impact on worm physiology. The results of gene knockout studies showed that C. elegans GCP2 orthologs affect the pharyngeal physiology, reproduction, and structural integrity of the organism. Promoter-driven GFP expression revealed distinct localization for each of the three gene paralogs, with gcp-2.1 being most abundant in muscles, intestine, and pharyngeal interneurons, gcp-2.2 restricted to the phasmid neurons, and gcp-2.3 located in the excretory cell. The present study provides new insight into the unique phenotypic effects of GCP2 gene knockouts in C. elegans, and the specific tissue localizations. We believe that elucidation of particular roles in a non-mammalian organism can help to explain important questions linked to physiology of this protease group and in extension to human GCP2 involvement in pathophysiological processes.

Type 1 interferon signature and cytotoxic T lymphocyte activation targeted against sweat ducts in inflammatory acquired idiopathic generalized anhidrosis

BACKGROUND

Acquired idiopathic generalized anhidrosis (AIGA) leads to heat intolerance due to the loss or reduction in thermoregulatory sweating over an extensive area of the body. The pathomechanism of AIGA is still unclear but is believed to be autoimmune.

OBJECTIVES

We investigated the clinical and pathological features of inflammatory AIGA (InfAIGA) and noninflammatory AIGA (non-InfAIGA) within the skin.

METHODS

We compared anhidrotic and normohidrotic skin samples from 30 patients with InfAIGA and non-InfAIGA, as well as skin samples of melanocytic nevus as a negative control. We conducted morphometric analysis and immunohistochemical analysis of cell types and expression of inflammatory molecules (TIA1, CXCR3 and MxA). MxA expression was used as a proxy for type 1 interferon activity.

RESULTS

We found that tissue samples from patients with InfAIGA exhibited inflammation within the sweat duct and atrophy of the sweat coil, whereas patients with non-InfAIGA exhibited only atrophy of the sweat coil. Cytotoxic T lymphocyte infiltration and MxA expression were only observed in the sweat ducts of patients with InfAIGA.

CONCLUSIONS

InfAIGA is associated with increased sweat duct inflammation and sweat coil atrophy, whereas non-InfAIGA is only associated with sweat coil atrophy. These data suggest that inflammation leads to epithelial destruction of sweat ducts associated with the sweat coil atrophy and subsequent loss of function. Non-InfAIGA may be regarded as a postinflammatory state of InfAIGA. These observations indicate the contribution of both type 1 and type 2 interferons to sweat gland injury. The mechanism involved is similar to the pathomechanism of alopecia areata (AA).

Computational resources to define alleles and altered regulatory motifs at genomically edited candidate response elements

Unequivocal functional assessment of candidate genomic regulatory regions, such as transcriptional response elements, requires genetic alteration at their native chromosomal loci. Targeted DNA cleavage by Cas9 or other programmable nucleases enables analysis at virtually any genomic region, and diverse alleles generated by editing can be defined by deep sequencing for functional analysis. Interpretation of disrupted response elements, however, presents a special challenge, as these regions typically comprise clustered DNA binding motifs for multiple transcriptional regulatory factors (TFs); DNA sequence differences, natural or engineered, that affect binding by one TF can confer loss or gain of binding sites for other TFs. To address these and other analytical complexities, we created three computational tools that together integrate, in a single experiment, allele definition and TF binding motif evaluation for up to 9216 clones isolated, sequenced and propagated from Cas9-treated cell populations. We demonstrate 1) the capacity to functionally assess edited TF binding sites to query response element function, and 2) the efficacy and utility of these tools, by analyzing cell populations targeted by Cas9 for disruption of example glucocorticoid receptor (GR) binding motifs near FKBP5, a GR-regulated gene in the human adenocarcinoma cell line A549.

Degranulation and shrinkage of dark cells in eccrine glands and elevated serum carcinoembryonic antigen in patients with acquired idiopathic generalized anhidrosis

BACKGROUND

Acquired idiopathic generalized anhidrosis (AIGA) is characterized by anhidrosis/hypohidrosis without other autonomic and neurological dysfunctions. Pathologically, AIGA is considered to usually present no significant morphological alterations in eccrine glands, the secretory portion which consists of clear cells, dark cells, and myoepithelial cells. AIGA patients recently have been reported to show high serum concentrations of carcinoembryonic antigen (CEA).

OBJECTIVE

Our aim is to reveal morphological abnormalities of dark cells and investigate their relationship with serum CEA.

METHODS

We performed comparative analysis of eccrine glands between sweat-preserved and non-sweating skin in four AIGA patients. Serum CEA concentrations in 22 cases with AIGA were measured with healthy volunteers. Furthermore, we semiquantitatively investigated dermcidin, FoxA1 and CEA expression in eccrine glands of 12 cases with AIGA and 5 cases with non-AIGA.

RESULTS

Marked degranulation and shrinkage of dark cells consistently occurred in AIGA. Furthermore, high serum CEA concentrations were found in 14 of 22 AIGA patients (over 60%), but serum CEA levels were not correlated with CEA expression in eccrine glands. Dermcidin expression in dark cells apparently decreased in AIGA patients, severely in those with high serum CEA and moderately in those with low serum CEA, while well-preserved expression was found in non-AIGA subjects.

CONCLUSION

Our study suggests morphological damage and molecular dysregulation of dark cells, leading to impairment of their functions in AIGA patients. Severely damaged dark cells correspond to high serum CEA. Accordingly, these pathological changes in eccrine dark cells may be involved in anhidrosis/hypohidrosis of AIGA.

SUMO as a nuclear hormone receptor effector: New insights into combinatorial transcriptional regulation

Animal development is driven by robust, cell-specific gene expression programs. Understanding mechanistically how a single transcription factor (TF) can govern distinct programs with exquisite precision is a major challenge. We view TFs as signal integrators, taking information from co-regulator interactions, post-translational modifications, other transcription factors, chromatin state, DNA sequence and in some cases, specific noncovalent ligands, to determine the collection of genes regulated by a TF at any given time. Here, we describe a reductionist approach to combinatorial transcriptional regulation, focusing on a single C. elegans TF, the nuclear hormone receptor NHR-25, and a single post-translational modification, SUMO. We suggest that the ratio of sumoylated to unsumoylated NHR-25 could specify a switch-like cell-fate decision during vulval development. Direct examination of this "SUMO ratio" in vivo is challenging and we discuss possible solutions going forward. We also consider how sumoylation of multiple substrates might be coordinated during vulval development. Finally, we note that iteration of this approach could leverage our sumoylation findings to define the roles of other effectors of NHR-25 in the developing vulva and in other tissues.

Sumoylated NHR-25/NR5A regulates cell fate during C. elegans vulval development

Individual metazoan transcription factors (TFs) regulate distinct sets of genes depending on cell type and developmental or physiological context. The precise mechanisms by which regulatory information from ligands, genomic sequence elements, co-factors, and post-translational modifications are integrated by TFs remain challenging questions. Here, we examine how a single regulatory input, sumoylation, differentially modulates the activity of a conserved C. elegans nuclear hormone receptor, NHR-25, in different cell types. Through a combination of yeast two-hybrid analysis and in vitro biochemistry we identified the single C. elegans SUMO (SMO-1) as an NHR-25 interacting protein, and showed that NHR-25 is sumoylated on at least four lysines. Some of the sumoylation acceptor sites are in common with those of the NHR-25 mammalian orthologs SF-1 and LRH-1, demonstrating that sumoylation has been strongly conserved within the NR5A family. We showed that NHR-25 bound canonical SF-1 binding sequences to regulate transcription, and that NHR-25 activity was enhanced in vivo upon loss of sumoylation. Knockdown of smo-1 mimicked NHR-25 overexpression with respect to maintenance of the 3° cell fate in vulval precursor cells (VPCs) during development. Importantly, however, overexpression of unsumoylatable alleles of NHR-25 revealed that NHR-25 sumoylation is critical for maintaining 3° cell fate. Moreover, SUMO also conferred formation of a developmental time-dependent NHR-25 concentration gradient across the VPCs. That is, accumulation of GFP-tagged NHR-25 was uniform across VPCs at the beginning of development, but as cells began dividing, a smo-1-dependent NHR-25 gradient formed with highest levels in 1° fated VPCs, intermediate levels in 2° fated VPCs, and low levels in 3° fated VPCs. We conclude that sumoylation operates at multiple levels to affect NHR-25 activity in a highly coordinated spatial and temporal manner.

Risk factors for cerebral arteriosclerosis in Parkinson's disease

A previous study showed a lower incidence of ischemic stroke in patients with Parkinson's disease (PD) than in controls. It has been speculated that this may be related to less severe atherosclerosis in PD. In this study we examined the magnetic resonance imaging (MRI) and blood chemistry in 106 parkinsonian patients and compared the data with those from control cases. Abnormal MRI findings (état criblé, lacunar infarctions or periventricular hyperintensity) were found in 55.7% of cases. No case of cortical artery infarction was found. In comparison with a control population, the PD group showed a lower frequency of hypercholesterolemia, a higher frequency of low HDL cholesterol and a lower frequency of obesity. These results suggest that patients with PD have a reduction in risk factors for cortical artery infarction.

Preserved autonomic function in patients with POEMS syndrome

AIM

We systematically performed autonomic testing on patients with polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes syndrome (POEMS) to determine whether autonomic function is preserved in such patients.

METHODS

We studied 17 POEMS patients, 17 diabetic neuropathy (DN) patients and 17 age-matched normal subjects. Blood pressure responses to the head-up tilt test and heart rate variability were used to evaluate cardiovascular autonomic function. Sweat responses and cutaneous vasoconstriction to several stimuli were recorded via the finger tips to estimate cutaneous sympathetic function. In addition, motor nerve conduction studies were performed.

RESULTS

Although the results of the autonomic testing were normal in POEMS patients, motor disability was severe, and motor nerve conduction studies provided evidence of extensive axonal loss. The DN patients showed significantly impaired autonomic responses despite mild motor dysfunction.

CONCLUSIONS

Autonomic function was normal in POEMS patients, indicating the preservation of autonomic fibers and selective involvement of large fibers.

The nuclear receptor gene nhr-25 plays multiple roles in the Caenorhabditis elegans heterochronic gene network to control the larva-to-adult transition

Developmental timing in the nematode Caenorhabditis elegans is controlled by heterochronic genes, mutations in which cause changes in the relative timing of developmental events. One of the heterochronic genes, let-7, encodes a microRNA that is highly evolutionarily conserved, suggesting that similar genetic pathways control developmental timing across phyla. Here we report that the nuclear receptor nhr-25, which belongs to the evolutionarily conserved fushi tarazu-factor 1/nuclear receptor NR5A subfamily, interacts with heterochronic genes that regulate the larva-to-adult transition in C. elegans. We identified nhr-25 as a regulator of apl-1, a homolog of the Alzheimer's amyloid precursor protein-like gene that is downstream of let-7 family microRNAs. NHR-25 controls not only apl-1 expression but also regulates developmental progression in the larva-to-adult transition. NHR-25 negatively regulates the expression of the adult-specific collagen gene col-19 in lateral epidermal seam cells. In contrast, NHR-25 positively regulates the larva-to-adult transition for other timed events in seam cells, such as cell fusion, cell division and alae formation. The genetic relationships between nhr-25 and other heterochronic genes are strikingly varied among several adult developmental events. We propose that nhr-25 has multiple roles in both promoting and inhibiting the C. elegans heterochronic gene pathway controlling adult differentiation programs.

Reduced perfusion in the anterior cingulate cortex of patients with pure autonomic failure: an 123I-IMP SPECT study

BACKGROUND

Pure autonomic failure (PAF) is a selective peripheral disorder in which Lewy bodies form within the autonomic ganglia. Patients with this disorder usually have no central lesions; however, chronic autonomic failure may secondarily affect the central nervous system. This study evaluated brain perfusion in patients with PAF by using N-isopropyl-p-(123)I iodoamphetamine ((123)I-IMP) single photon emission computed tomography (SPECT).

METHODS

Six patients with PAF (all men; mean (SD) age 68+/-5 years) who had experienced autonomic symptoms for more than 5 years and six age-matched healthy control subjects (all men; mean (SD) age 67+/-5 years) were included in this study. The regions of interest (ROI) on spacially normalized (123)I-IMP SPECT images were automatically computed for both groups.

RESULTS

Perfusion of the dorsal anterior cingulate cortex was decreased in the PAF group compared with the healthy control group (0.93 vs 1.01; p<0.001). In the other brain regions measured, there was no significant difference in regional perfusion between the two groups.

CONCLUSIONS

The dorsal anterior cingulate cortex is poorly perfused and may be functionally altered in patients with PAF. The reduced perfusion in such individuals may be a secondary change that results from chronic autonomic failure.

Sudomotor, skin vasomotor, and cardiovascular reflexes in 3 clinical forms of Lewy body disease

OBJECTIVE

To elucidate the differences among dementia with Lewy bodies (DLB), Parkinson disease with dementia (PDD), and Parkinson disease without dementia (PD), with respect to the involvement of the autonomic nervous system, we clinically investigated the cutaneous and cardiovascular autonomic functions in patients with Lewy body disease.

METHODS

We studied 36 patients with Lewy body disorders, including 12 patients with DLB (age, 75.4 +/- 5.9 years), 12 patients with PDD (71.0 +/- 6.8 years), and 12 patients with PD (70.9 +/- 4.2 years), and 12 healthy control subjects (69.9 +/- 5.3 years). Sympathetic sweat response (SSwR) and skin vasomotor reflex (SkVR) on the palm were recorded to estimate the cutaneous sympathetic function, and the head-up tilt test was performed and coefficient of variation of R-R intervals (CV(R-R)) was studied to estimate the cardiovascular function.

RESULTS

The patients with DLB, patients with PDD, and patients with PD showed severely reduced SSwR amplitudes, significantly lower than that in the controls. The mean SkVR amplitudes in the patients with DLB and patients with PDD were significantly lower than that in the controls, but not in the patients with PD. The mean decreases in the systolic blood pressure during the head-up tilt test in the patients with DLB and patients with PDD were less than that in the controls. The mean CV(R-R) value was significantly lower in the patients with DLB.

CONCLUSION

Sudomotor function on the palm may be severely affected in Lewy body disorders, while skin vasomotor function and the cardiovascular system may be more severely affected in dementia with Lewy bodies and Parkinson disease with dementia than in Parkinson disease.

The nuclear receptor NHR-25 cooperates with the Wnt/beta-catenin asymmetry pathway to control differentiation of the T seam cell in C. elegans

Asymmetric cell divisions produce new cell types during animal development. Studies in Caenorhabditis elegans have identified major signal-transduction pathways that determine the polarity of cell divisions. How these relatively few conserved pathways interact and what modulates them to ensure the diversity of multiple tissue types is an open question. The Wnt/beta-catenin asymmetry pathway governs polarity of the epidermal T seam cell in the C. elegans tail. Here, we show that the asymmetry of T-seam-cell division and morphogenesis of the male sensory rays require NHR-25, an evolutionarily conserved nuclear receptor. NHR-25 ensures the neural fate of the T-seam-cell descendants in cooperation with the Wnt/beta-catenin asymmetry pathway. Loss of NHR-25 enhances the impact of mutated nuclear effectors of this pathway, POP-1 (TCF) and SYS-1 (beta-catenin), on T-seam-cell polarity, whereas it suppresses the effect of the same mutations on asymmetric division of the somatic gonad precursor cells. Therefore, NHR-25 can either synergize with or antagonize the Wnt/beta-catenin asymmetry pathway depending on the tissue context. Our findings define NHR-25 as a versatile modulator of Wnt/beta-catenin-dependent cell-fate decisions.

Mapping of brain acetylcholinesterase alterations in Lewy body disease by PET

OBJECTIVE

To characterize brain cholinergic deficits in Parkinson disease (PD), PD with dementia (PDD), and dementia with Lewy bodies (DLB).

METHODS

Participants included 18 patients with PD, 21 patients with PDD/DLB, and 26 healthy controls. The PD group consisted of nine patients with early PD, each with a disease duration of less than 3 years, five of whom were de novo PD patients, and nine patients with advanced PD, each with a disease duration greater than or equal to 3 years. The PDD/DLB group consisted of 10 patients with PDD and 11 patients with DLB. All subjects underwent PET scans with N-[11C]-methyl-4-piperidyl acetate to measure brain acetylcholinesterase (AChE) activity. Brain AChE activity levels were estimated voxel-by-voxel in a three-compartment analysis using the arterial input function, and compared among our subject groups through both voxel-based analysis using the statistical parametric mapping software SPM5 and volume-of-interest analysis.

RESULTS

Among patients with PD, AChE activity was significantly decreased in the cerebral cortex and especially in the medial occipital cortex (% reduction compared with the normal mean = -12%) (false discovery rate-corrected p value <0.01). Patients with PDD/DLB, however, had even lower AChE activity in the cerebral cortex (% reduction = -27%) (p < 0.01). There was no significant difference between early PD and advanced PD groups or between DLB and PDD groups in the amount by which regional AChE activity in the brain was reduced.

CONCLUSIONS

Brain cholinergic dysfunction occurs in the cerebral cortex, especially in the medial occipital cortex. It begins in early Parkinson disease, and is more widespread and profound in both Parkinson disease with dementia and dementia with Lewy bodies.

Clinical and brain MR imaging features focusing on the brain stem and cerebellum in patients with myoclonic epilepsy with ragged-red fibers due to mitochondrial A8344G mutation

SUMMARY

We report 3 patients with myoclonic epilepsy with ragged-red fibers (MERRF) diagnosed by mitochondrial A8344G mutation. Cerebellar ataxia was the first symptom in all patients. Conventional brain MR imaging showed atrophy of the superior cerebellar peduncles and the cerebellum in all patients and brain stem atrophy in 2 patients. In diffusion tensor analysis, fractional anisotropy of the superior cerebellar peduncles was mildly decreased in 1 patient. There was a discrepancy between clinical disabilities (severe) and radiologic abnormalities (mild). This discrepancy and atrophy of the superior cerebellar peduncles and the cerebellum may be important findings suggesting a diagnosis of MERRF.

Crosstalk between a nuclear receptor and beta-catenin signaling decides cell fates in the C. elegans somatic gonad

beta-Catenin signaling determines the proximal-distal axis of the C. elegans gonad by promoting distal fate in asymmetrically dividing somatic gonad precursor cells (SGPs). Impaired function of the Wnt effector POP-1/TCF, its coactivator SYS-1/beta-catenin, and of upstream components including beta-catenin WRM-1 causes all SGP daughters to adopt the proximal fate. Consequently, no distal tip cells (DTCs) that would lead differentiation of gonad arms form in the affected hermaphrodites. Here, we show that deficiency of the nuclear receptor NHR-25 has the opposite effect: extra DTCs develop instead of proximal cells. NHR-25 knockdown restores DTC formation and fertility in pop-1 and sys-1 mutants, suggesting that a balance between NHR-25 and beta-catenin pathway activities is required to establish both proximal and distal fates. This balance relies on direct crossregulation between NHR-25 and the distinct beta-catenin proteins WRM-1 and SYS-1. The nuclear receptor-beta-catenin interaction may be an ancient mechanism of cell-fate decision.

Skin vasomotor reflex responses in two contrasting groups of autonomic failure

BACKGROUND & AIM

A variety of stimuli such as deep inspiration, isometric exercise and mental arithmetic, result in a transient vasoconstriction,mediated by sympathetic efferent nerves, in the skin of the fingers and toes of healthy controls (Skin Vasomotor Reflex: SkVR). Multiple system atrophy (MSA) and pure autonomic failure (PAF) provide contrasting models of autonomic failure. In MSA the lesion is central and preganglionic, whilst in PAF the lesion site is peripheral and postganglionic. We evaluated the SkVR in response to various stimuli in MSA and PAF, to determine differences in skin vasomotor involvement between these two patient groups.

METHODS

25 subjects (10 MSA, 7 PAF, 8 healthy controls) were studied. Baseline recordings of skin blood flow were obtained with a laser Doppler probe on the left index finger pulp and forearm. The subject then underwent a variety of stimuli with rest periods in between to reestablish baseline SkBF. These stimuli were: single deep inspiration (inspiratory gasp); mental arithmetic; bilateral leg elevation and cutaneous cold.

RESULTS

Healthy control subjects demonstrated marked SkVRs on the finger pulp to each of the stimuli of a magnitude similar to those seen in previous studies, but no SkVRs on the forearm. In MSA SkVRs to inspiratory gasp on the finger pulp were reduced relative to controls. In PAF SkVRs were reduced relative to controls or MSA. The magnitude of SkVR response to gasp and cutaneous cold in PAF was significantly less than in healthy controls. In addition, the magnitude of the response in PAF was significantly less than in MSA for inspiratory gasp.

CONCLUSIONS

PAF showed a decreased SkVR response to all 4 stimuli, the response being significantly less than controls (for inspiratory gasp and cutaneous cold) or MSA (cutaneous cold inspiratory gasp). The decreased responses in PAF may reflect the extensive postganglionic sympathetic denervation seen in this group. The measurement of SkVR may therefore provide a non-invasive aid to the differentiation of MSA and PAF.

PARK6-linked autosomal recessive early-onset parkinsonism in Asian populations

The authors performed linkage analysis in 39 families with autosomal recessive early-onset PD (AR-EOPD) negative for parkin and DJ-1 mutations. Eight families including three Japanese, two Taiwanese, one Turkish, one Israeli, and one Philippine showed evidence of linkage with PARK6 with multipoint log of the odds (lod) score of 9.88 at D1S2732. The results indicate worldwide distribution of PARK6-linked parkinsonism.