Deleterious variants in CRLS1 lead to cardiolipin deficiency and cause an autosomal recessive multi-system mitochondrial disease.

Mitochondrial diseases are a group of inherited diseases with highly varied and complex clinical presentations. Here, we report four individuals, including two siblings, affected by a progressive mitochondrial encephalopathy with biallelic variants in the cardiolipin biosynthesis gene CRLS1. Three affected individuals had a similar infantile presentation comprising progressive encephalopathy, bull's eye maculopathy, auditory neuropathy, diabetes insipidus, autonomic instability, cardiac defects and early death. The fourth affected individual presented with chronic encephalopathy with neurodevelopmental regression, congenital nystagmus with decreased vision, sensorineural hearing loss, failure to thrive and acquired microcephaly. Using patient-derived fibroblasts, we characterized cardiolipin synthase 1 (CRLS1) dysfunction that impaired mitochondrial morphology and biogenesis, providing functional evidence that the CRLS1 variants cause mitochondrial disease. Lipid profiling in fibroblasts from two patients further confirmed the functional defect demonstrating reduced cardiolipin levels, altered acyl-chain composition and significantly increased levels of phosphatidylglycerol, the substrate of CRLS1. Proteomic profiling of patient cells and mouse Crls1 knockout cell lines identified both endoplasmic reticular and mitochondrial stress responses, and key features that distinguish between varying degrees of cardiolipin insufficiency. These findings support that deleterious variants in CRLS1 cause an autosomal recessive mitochondrial disease, presenting as a severe encephalopathy with multi-systemic involvement. Furthermore, we identify key signatures in cardiolipin and proteome profiles across various degrees of cardiolipin loss, facilitating the use of omics technologies to guide future diagnosis of mitochondrial diseases.

Concordant palliative care delivery in advanced head and neck cancer.

OBJECTIVES: To describe the palliative care consultation practices in an academic head and neck surgery practice. METHODS: This is a retrospective review of a palliative care database and the health record for all palliative care consultations of patients suffering from advanced stage head and neck cancer within a 21-month period. RESULTS: Ten head and neck cancer patients received palliative care consults while on the otolaryngology service. One consultation occurred preoperatively; nine occurred postoperatively, on a median of hospital day 9. At the time of referral, seven patients were in the ICU and three were on a surgical floor. Code status de-escalation occurred in six patients and psycho-socio-spiritual suffering was supported in all consultations. Nine patients died within six months, with a median post-consultation survival of 35 days. Of these, two died in an ICU, five were discharged to hospice, one to a SNF, and one to a LTACH. CONCLUSION: Palliative care consultation in this advanced head and neck cancer cohort was commonly late, however, significant suffering was mitigated following most consults. Palliative care specialists are experts at eliciting patient values, determining acceptable tradeoffs and suffering limitations by employing a shared decision-making process that ends with a patient-centered value-congruent treatment recommendation. Oftentimes, this embraces curative-intent or palliative surgery, along with contingency plans for unacceptable value-incongruent postoperative outcomes. Enhanced awareness of the benefits of embracing concordant palliative care in advanced head and neck cancer patients may help overcome the significant barriers to involving palliative care experts earlier.

VEXAS syndrome: lessons learnt from an early Australian case series.

VEXAS is a newly recognised adult-onset autoinflammatory syndrome resulting from a somatic mutation in the UBA1 gene. Herein, we present three cases of VEXAS syndrome in Sydney, Australia, that capture key clinical features and the refractory nature of the condition. They highlight the importance of multidisciplinary collaboration for early diagnosis and the need for new therapeutic options.

Can Expressing Positivity Elicit Support for Negative Events? A Process Model and Review.

Garnering support for distressing experiences is highly important, yet notoriously challenging. We examine whether expressing positive thoughts and feelings when seeking support for negative events can help people elicit support, and we present a theoretical process model that explains why it might do so. The model includes three support-eliciting pathways through which expressing positivity could increase support: by strengthening providers' prorelational motives, increasing providers' positive mood, and enhancing providers' expected support effectiveness. It also includes a support-suppressing pathway through which expressing positivity could decrease support: by undermining providers' appraisals of support seekers' needs. After presenting the model and providing evidence for each indirect pathway, we review research regarding the direct pathway. We then consider various types of positivity, discuss possible moderators, and identify directions for future research. Our model highlights support seekers' underemphasized role in shaping support receipt and provides a novel perspective on positive expressivity's potential value in distress-related contexts.

Genetic and microbial factors modulating the ubiquitin proteasome system in inflammatory bowel disease.

OBJECTIVE: Altered microbiota composition, changes in immune responses and impaired intestinal barrier functions are observed in IBD. Most of these features are controlled by proteases and their inhibitors to maintain gut homeostasis. Unrestrained or excessive proteolysis can lead to pathological gastrointestinal conditions. The aim was to validate the identified protease IBD candidates from a previously performed systematic review through a genetic association study and functional follow-up. DESIGN: We performed a genetic association study in a large multicentre cohort of patients with Crohn's disease (CD) and UC from five European IBD referral centres in a total of 2320 CD patients, 2112 UC patients and 1796 healthy controls. Subsequently, we did an extensive functional assessment of the candidate genes to explore their causality in IBD pathogenesis. RESULTS: Ten single nucleotide polymorphisms (SNPs) in four genes were significantly associated with CD: CYLD, USP40, APEH and USP3. CYLD was the most significant gene with the intronically located rs12324931 the strongest associated SNP (p(FDR)=1.74e-17, OR=2.24 (1.83 to 2.74)). Five SNPs in four genes were significantly associated with UC: USP40, APEH, DAG1 and USP3. CYLD, as well as some of the other associated genes, is part of the ubiquitin proteasome system (UPS). We therefore determined if the IBD-associated adherent-invasive Escherichia coli (AIEC) can modulate the UPS functioning. Infection of intestinal epithelial cells with the AIEC LF82 reference strain modulated the UPS turnover by reducing poly-ubiquitin conjugate accumulation, increasing 26S proteasome activities and decreasing protein levels of the NF-κB regulator CYLD. This resulted in IκB-α degradation and NF-κB activation. This activity was very important for the pathogenicity of AIEC since decreased CYLD resulted in increased ability of AIEC LF82 to replicate intracellularly. CONCLUSIONS: Our results reveal the UPS, and CYLD specifically, as an important contributor to IBD pathogenesis, which is favoured by both genetic and microbial factors.

Expressing the good in bad times: Examining whether and why positive expressivity in negative contexts affects romantic partners' responsive support provision.

Receiving high-quality, responsive support in times of distress is critical but difficult. In a theoretical review, we previously proposed a process model that explains why support-seekers' positive expressivity can elicit-but may sometimes suppress-supportive responses from partners (providers) within distress-related contexts. In the current work, we aimed to test direct and indirect pathways linking seeker's positive expressivity in negative disclosures to provider's support while addressing notable gaps in the existing literature. Studies considered seeker-expressed positivity as broad, unitary construct (Studies 1, 2, and 4) and explored different types of positivity (Studies 1, 3, and 4): partner-oriented positivity (e.g., gratitude), stressor-oriented positivity (e.g., optimism), and unspecified positivity (e.g., pleasant demeanor). In behavioral observation studies of romantic couples (Studies 1 and 4), seeker-expressed positivity in negative disclosures positively predicted provider responsiveness, even when controlling for seeker-expressed negativity and other plausible third variables. Online experiments with manipulations of seeker-expressed positivity (Studies 2 and 3) yielded causal evidence of positivity's direct support-eliciting effects. Considering positivity types, partner-oriented positivity and stressor-oriented positivity showed the most robust support-eliciting potential; unspecified positivity also appeared valuable in some contexts. Evidence for several of the model's indirect pathways emerged in correlational (Study 4) and experimental (Studies 2 and 3) work, providing insights into support-eliciting and support-suppressing mechanisms through which positivity operates. These findings underscore support-seekers' active role in obtaining support, highlight the value of positive expressivity for eliciting high-quality support, and lay the groundwork for further research on positive expressivity's effects in support-seeking contexts. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Quantifying the costs of hospital admission for families of children with a febrile illness in the North East of England.

OBJECTIVE: To assess the financial non-medical out-of-pocket costs of hospital admissions for children with a febrile illness. DESIGN: Single-centre survey-based study conducted between March and November 2022. SETTING: Tertiary level children's hospital in the North East of England. PARTICIPANTS: Families of patients with febrile illness attending the paediatric emergency department MAIN OUTCOME MEASURES: Non-medical out-of-pocket costs for the admission were estimated by participants including: transport, food and drinks, child care, miscellaneous costs and loss of earnings. RESULTS: 83 families completed the survey. 79 families (95.2%) reported non-medical out-of-pocket costs and 19 (22.9%) reported financial hardship following their child's admission.Total costs per day of admission were median £56.25 (IQR £32.10-157.25). The majority of families reported incurring transport (N=75) and food and drinks (N=71) costs. CONCLUSIONS: A child's hospital admission for fever can incur significant financial costs for their family. One in five participating families reported financial hardship following their child's admission. Self-employed and single parents were disadvantaged by unplanned hospital admissions and at an increased risk of financial hardship. Local hospital policies should be improved to support families in the current financial climate.

Dominant negative OTULIN-related autoinflammatory syndrome.

OTU deubiquitinase with linear linkage specificity (OTULIN) regulates inflammation and cell death by deubiquitinating linear ubiquitin chains generated by the linear ubiquitin chain assembly complex (LUBAC). Biallelic loss-of-function mutations causes OTULIN-related autoinflammatory syndrome (ORAS), while OTULIN haploinsuffiency has not been associated with spontaneous inflammation. However, herein, we identify two patients with the heterozygous mutation p.Cys129Ser in OTULIN. Consistent with ORAS, we observed accumulation of linear ubiquitin chains, increased sensitivity to TNF-induced death, and dysregulation of inflammatory signaling in patient cells. While the C129S mutation did not affect OTULIN protein stability or binding capacity to LUBAC and linear ubiquitin chains, it did ablate OTULIN deubiquitinase activity. Loss of activity facilitated the accumulation of autoubiquitin chains on LUBAC. Altered ubiquitination of LUBAC inhibits its recruitment to the TNF receptor signaling complex, promoting TNF-induced cell death and disease pathology. By reporting the first dominant negative mutation driving ORAS, this study expands our clinical understanding of OTULIN-associated pathology.

Targeting pan-resistant bacteria with antibodies to a broadly conserved surface polysaccharide expressed during infection.

BACKGROUND: New therapeutic targets for antibiotic-resistant bacterial pathogens are desperately needed. The bacterial surface polysaccharide poly-ß-(1-6)-N-acetyl-glucosamine (PNAG) mediates biofilm formation by some bacterial species, and antibodies to PNAG can confer protective immunity. By analyzing sequenced genomes, we found that potentially multidrug-resistant bacterial species such as Klebsiella pneumoniae, Enterobacter cloacae, Stenotrophomonas maltophilia, and the Burkholderia cepacia complex (BCC) may be able to produce PNAG. Among patients with cystic fibrosis patients, highly antibiotic-resistant bacteria in the BCC have emerged as problematic pathogens, providing an impetus to study the potential of PNAG to be targeted for immunotherapy against pan-resistant bacterial pathogens. METHODS: The presence of PNAG on BCC was assessed using a combination of bacterial genetics, microscopy, and immunochemical approaches. Antibodies to PNAG were tested using opsonophagocytic assays and for protective efficacy against lethal peritonitis in mice. RESULTS: PNAG is expressed in vitro and in vivo by the BCC, and cystic fibrosis patients infected by the BCC species B. dolosa mounted a PNAG-specific opsonophagocytic antibody response. Antisera to PNAG mediated opsonophagocytic killing of BCC and were protective against lethal BCC peritonitis even during coinfection with methicillin-resistant Staphylococcus aureus. CONCLUSIONS: Our findings raise potential new therapeutic options against PNAG-producing bacteria, including even pan-resistant pathogens.

Parental perspectives on emergency health service use during the first wave of the COVID-19 pandemic in the United Kingdom: A qualitative study.

UK 'Lockdown' measures introduced in March 2020 aimed to mitigate the spread of COVID-19. Although seeking healthcare was still permitted within restrictions, paediatric emergency department attendances reduced dramatically and led to concern over risks caused by delayed presentation. Our aim was to gain insight into healthcare decisions faced by parents during the first wave of the COVID-19 pandemic and to understand if use of urgent healthcare, self-care, and information needs differed during lockdown as well as how parents perceived risks of COVID-19. We undertook qualitative telephone interviews with a purposive sample of parents living in the North East of England recruited through online advertising. We used a semi-structured interview schedule to explore past and current healthcare use, perceptions of risk and the impact of the pandemic on healthcare decisions. Interviews were transcribed and analysed using Thematic Analysis. Three major themes were identified which concerned (i) how parents made sense of risks posed to, and by their children, (ii) understanding information regarding health services and (iii) attempting to make the right decision. These themes contribute to the understanding of the initial impact of COVID-19 and associated restrictions on parental decisions about urgent healthcare for children. These findings are important to consider when planning for potential future public health emergencies but also in the wider context of encouraging appropriate use of urgent healthcare.

Specific and shared targets of ephrin A signaling in epidermal keratinocytes.

Both ephrins (EFNs) and their receptors (Ephs) are membrane-bound, restricting their interactions to the sites of direct cell-to-cell interfaces. They are widely expressed, often co-expressed, and regulate developmental processes, cell adhesion, motility, survival, proliferation, and differentiation. Both tumor suppressor and oncogene activities are ascribed to EFNs and Ephs in various contexts. A major conundrum regarding the EFN/Eph system concerns their large number and functional redundancy given the promiscuous cross-activation of ligands and receptors and the overlapping intracellular signaling pathways. To address this issue, we treated human epidermal keratinocytes with five EFNAs individually and defined the transcriptional responses in the cells. We found that a large set of genes is coregulated by all EFNAs. However, although the responses to EFNA3, EFNA4, and EFNA5 are identical, the responses to EFNA1 and EFNA2 are characteristic and distinctive. All EFNAs induce epidermal differentiation markers and suppress cell adhesion genes, especially integrins. Ontological analysis showed that all EFNAs induce cornification and keratin genes while suppressing wound healing-associated, signaling, receptor, and extracellular matrix-associated genes. Transcriptional targets of AP1 are selectively suppressed by EFNAs. EFNA1 and EFNA2, but not the EFNA3, EFNA4, EFNA5 cluster, regulate the members of the ubiquitin-associated proteolysis genes. EFNA1 specifically induces collagen production. Our results demonstrate that the EFN-Eph interactions in the epidermis, although promiscuous, are not redundant but specific. This suggests that different members of the EFN/Eph system have specific, clearly demarcated functions.

Eph-2B, acting as an extracellular ligand, induces differentiation markers in epidermal keratinocytes.

In the bi-directional signaling system comprising ephrins (EFNs) and ephrin receptors (Ephs), both EFNs and Ephs simultaneously function both as ligands and as receptors. Importantly, the EFN/Eph system is deregulated in human cancers and has been implicated in the metastatic processes because of its effects on the adhesion and migration of epithelial cells. The idiosyncratic function of Ephs, membrane-bound receptor kinases, as extracellular signaling ligands, has not been extensively studied. This prompted us to explore the transcriptional targets regulated by Ephs acting solely as ligands. To define the ligand function of EphB2 in human epidermal keratinocytes, we treated these cells with EphB2 as Fc-conjugate dimmers, which thus act exclusively as extracellular ligands. We compared the EphB2 and EFNA4 effects during a 48 h time course, using transcriptional profiling. We found that EphB2, acting as a ligand, promotes epidermal differentiation. For example, EphB2 induces expression of markers of epidermal differentiation, including keratins KRT1 and KRT10, SPRRs, desmosomal proteins and cell cycle inhibitors, while suppressing basal layer markers, integrins and cell cycle proteins. The effects of EphB2 are delayed relative to those of EFNA4. Unlike EFNA4, EphB2 did not induce lipid metabolism proteins, this particular aspect of epidermal differentiation seems not to be regulated by EphB2. Our results define the transcriptional targets of the reverse signaling by EphB2 acting exclusively as a ligand and begin to characterize this intriguing function of Ephs.

The spectrum and burden of in-patient paediatric musculoskeletal diseases in Northern Tanzania.

BACKGROUND: Musculoskeletal diseases (MSD) are a major contributor to the global burden of disease and disability, and disproportionally affect low- and middle-income countries; however, there is a dearth of epidemiological data. Affected children often face increased morbidity, social isolation and economic hardship. AIM: To assess the spectrum and burden of paediatric MSD in children aged 5-18 years admitted to a major referral hospital in Tanzania. METHODS: This was a retrospective cohort study of children aged 5-18 years admitted to Kilimanjaro Christian Medical Centre (KCMC) whose initial diagnosis was recognised as a musculoskeletal condition by the International Classification of Diseases-10 between 1 January and 31 December 2017. RESULTS: During 2017, 163 cases of confirmed paediatric MSD were admitted to KCMC, representing 21.2% of all admissions of children aged 5-18 years (n = 769). Bone disease was the most common diagnosis. They comprised 106 (65.0%) traumatic fractures, 31 (19.0%) osteo-articular infections, 9 (5.5%) malunions and 3 (1.8%) pathological fractures. Congenital defects and rheumatic disease were relatively uncommon, accounting for only 6 (3.7%) and 4 (2.5%) MSD admissions, respectively. CONCLUSION: The majority of cases of MSD were related to fractures, followed by osteo-articular infections, while recognised cases of rheumatic disease were rare. The study, although small, identified the sizeable burden and spectrum of paediatric MSD admitted to a hospital in Tanzania over a 12-month period and highlights the need for larger studies to inform the optimal allocation of health resources. ABBREVIATION: CI: confidence interval; HIC: high-income countries; HIV: human immunodeficiency virus; ICD-10: International Classification of Diseases 10; IQR: interquartile range; JIA: juvenile idiopathic arthritis; KCMC: Kilimanjaro Christian Medical Centre; LMIC: low- and middle-income countries; MSD: musculoskeletal diseases: NAI: non-accidental injury; NIHR: National Institute for Health Research; PAFLAR: Paediatric Society of the African League Against Rheumatism; RTA: road traffic accidents; SCD: sickle cell disease; SLE: systemic lupus erythematosus; SSA: sub-Saharan Africa.

The presence of professional phagocytes dictates the number of host cells targeted for Yop translocation during infection.

Type III secretion systems deliver effector proteins from Gram-negative bacterial pathogens into host cells, where they disarm host defences, allowing the pathogens to establish infection. Although Yersinia pseudotuberculosis delivers its effector proteins, called Yops, into numerous cell types grown in culture, we show that during infection Y. pseudotuberculosis selectively targets Yops to professional phagocytes in Peyer's patches, mesenteric lymph nodes and spleen, although it colocalizes with B and T cells as well as professional phagocytes. Strikingly, in the absence of neutrophils, the number of cells with translocated Yops was significantly reduced although the bacterial loads were similar, indicating that Y. pseudotuberculosis did not arbitrarily deliver Yops to the available cells. Using isolated splenocytes, selective binding and selective targeting to professional phagocytes when bacteria were limiting was also observed, indicating that tissue architecture was not required for the tropism for professional phagocytes. In isolated splenocytes, YadA and Invasin increased the number of all cells types with translocated Yops, but professional phagocytes were still preferentially translocated with Yops in the absence of these adhesins. Together these results indicate that Y. pseudotuberculosis discriminates among cells it encounters during infection and selectively delivers Yops to phagocytes while refraining from translocation to other cell types.

Clinically Responsive Genomic Analysis Pipelines: Elements to Improve Detection Rate and Efficiency.

Massively parallel sequencing has markedly improved mendelian diagnostic rates. This study assessed the effects of custom alterations to a diagnostic genomic bioinformatic pipeline in response to clinical need and derived practice recommendations relative to diagnostic rates and efficiency. The Genomic Annotation and Interpretation Application (GAIA) bioinformatics pipeline was designed to detect panel, exome, and genome sample integrity and prioritize gene variants in mendelian disorders. Reanalysis of selected negative cases was performed after improvements to the pipeline. GAIA improvements and their effect on sensitivity are described, including addition of a PubMed search for gene-disease associations not in the Online Mendelian Inheritance of Man database, inclusion of a process for calling low-quality variants (known as QPatch), and gene symbol nomenclature consistency checking. The new pipeline increased the diagnostic rate and reduced staff costs, resulting in a saving of US$844.34 per additional diagnosis. Recommendations for genomic analysis pipeline requirements are summarized. Clinically responsive bioinformatics pipeline improvements increase diagnostic sensitivity and increase cost-effectiveness.

IL-17 is a critical component of vaccine-induced protection against lung infection by lipopolysaccharide-heterologous strains of Pseudomonas aeruginosa.

In a murine model of acute fatal pneumonia, we previously showed that nasal immunization with a live-attenuated aroA deletant of Pseudomonas aeruginosa strain PAO1 elicited LPS serogroup-specific protection, indicating that opsonic Ab to the LPS O Ag was the most important immune effector. Because P. aeruginosa strain PA14 possesses additional virulence factors, we hypothesized that a live-attenuated vaccine based on PA14 might elicit a broader array of immune effectors. Thus, an aroA deletant of PA14, denoted PA14DeltaaroA, was constructed. PA14DeltaaroA-immunized mice were protected against lethal pneumonia caused not only by the parental strain but also by cytotoxic variants of the O Ag-heterologous P. aeruginosa strains PAO1 and PAO6a,d. Remarkably, serum from PA14DeltaaroA-immunized mice had very low levels of opsonic activity against strain PAO1 and could not passively transfer protection, suggesting that an antibody-independent mechanism was needed for the observed cross-serogroup protection. Compared with control mice, PA14DeltaaroA-immunized mice had more rapid recruitment of neutrophils to the airways early after challenge. T cells isolated from P. aeruginosa DeltaaroA-immunized mice proliferated and produced IL-17 in high quantities after coculture with gentamicin-killed P. aeruginosa. Six hours following challenge, PA14DeltaaroA-immunized mice had significantly higher levels of IL-17 in bronchoalveolar lavage fluid compared with unimmunized, Escherichia coli-immunized, or PAO1DeltaaroA-immunized mice. Antibody-mediated depletion of IL-17 before challenge or absence of the IL-17 receptor abrogated the PA14DeltaaroA vaccine's protection against lethal pneumonia. These data show that IL-17 plays a critical role in antibody-independent vaccine-induced protection against LPS-heterologous strains of P. aeruginosa in the lung.

Stuffing down feelings: Bereavement, anxiety and emotional detachment in the life stories of people with eating disorders.

This study aimed to explore the life stories of people with eating disorders (EDs) in order to better understand possible contributing factors to their development. It used a qualitative Life Story method, in order to reduce the tendency to focus on the negative in the lives of people with EDs. Sixteen people in contact with an EDs charity participated. Data were analysed using a thematic analysis. Despite the attempt to elicit both positive and negative information, most themes from the life stories were negative. Here, the focus is on the three most common themes reported, which are less often reported in previous research: (a) substantial bereavement and loss; (b) major issues with anxiety and (c) difficulties coping with emotions. A model is proposed whereby major losses and the resultant anxiety can lead to emotional deadening and 'stuffing down feelings' with food, leading on to an ED. This model implies that interventions need to consider psychological factors in an ED, especially the use of it as a dysfunctional coping strategy, as well as the behavioural and physiological aspects of an ED.

Transcriptional responses of human epidermal keratinocytes to cytokine interleukin-1.

Interleukin-1 is a proinflammatory and immunomodulatory cytokine that plays a crucial role in inflammatory diseases of the skin, including bacterial infections, bullous diseases, UV damage, and especially psoriasis. To characterize the molecular effects of IL-1 in epidermis, we defined the transcriptional changes in human epidermal keratinocytes 1, 4, 24, and 48 h after treatment with IL-1alpha. IL-1 significantly regulated 388 genes, including genes associated with proteolysis, adhesion, signal transduction, proliferation, and epidermal differentiation. IL-1 induces many genes that have antimicrobial function. Secreted cytokines, chemokines, growth factors, and their receptors are the prominent targets of IL-1 regulation, including IL-8, IL-19, elafin, C3, and S100A proteins, which implicate IL-1 in the pathogenesis of inflammatory diseases. IL-1 induced not only proliferation-associated genes but also differentiation marker genes such as transglutaminase-1 and involucrin, which suggests that IL-1 plays an important role in the aberrant proliferation and differentiation seen in psoriasis. Correlation of IL-1 regulated genes with the TNFalpha and IFNgamma regulated ones showed more similarities between IL-1 and TNFalpha than IL-1 and IFNgamma, whereas Oncostatin-M (OsM) affected a largely unrelated set of genes. IL-1 regulates many genes previously shown to be specifically over-expressed in psoriasis. In summary, IL-1 regulates a characteristic set of genes that define its specific contribution to inflammation and aberrant differentiation in skin diseases.

Transcriptional profiling defines the roles of ERK and p38 kinases in epidermal keratinocytes.

Epidermal keratinocytes respond to extracellular influences by activating cytoplasmic signal transduction pathways that change gene expression. Using pathway-specific transcriptional profiling, we identified the genes regulated by two such pathways, p38 and ERK. These pathways are at the fulcrum of epidermal differentiation, proliferative and inflammatory skin diseases. We used SB203580 and PD98059 as specific inhibitors and Affymetrix Hu133Av2 microarrays, to identify the genes regulated after 1, 4, 24, and 48 h and compared them to genes regulated by JNK. Unexpectedly, inhibition of MAPK pathways is compensated by activation of the NFkappaB pathway and suppression of the DUSP enzymes. Both pathways promote epidermal differentiation; however, there is a surprising disconnect between the expression of steroid synthesis enzymes and differentiation markers. The p38 pathway induces the expression of extracellular matrix and proliferation-associated genes, while suppressing microtubule-associated genes. The ERK pathway induces nuclear envelope and mRNA splicing proteins, while suppressing steroid synthesis and mitochondrial energy production enzymes. Transcription factors SRY, c-FOS, and N-Myc are the principal targets of the p38 pathway, Elk-1 SAP1 and HLH2 of ERK, while FREAC-4, ARNT and USF are shared. The results suggest a list of targets potentially useful in therapeutic interventions in cutaneous diseases and wound healing.