Differentiation of Keratinocytes Modulates Skin HPA Analog
JOURNAL OF CELLULAR PHYSIOLOGY
Authors: Wierzbicka, Justyna M.; Zmijewski, Michal A.; Antoniewicz, Jakub; Sobjanek, Michal; Slominski, Andrzej T.
Abstract
It is well established, that epidermal keratinocytes express functional equivalent of hypothalamus-pituitary-adrenal axis (HPA) in order to respond to changing environment and maintain internal homeostasis. We are presenting data indicating that differentiation of primary neonatal human keratinocytes (HPEKp), induced by prolonged incubation or calcium is accompanied by significant changes in the expression of the elements of skin analog of HPA (sHPA). Expression of CRF, UCN1-3, POMC, ACTH, CRFR1, CRFR2, MC1R, MC2R, and GR (coded by NR3C1 gene) were observed on gene/protein levels along differentiation of keratinocytes in culture with similar pattern seen by immunohistochemistry on full thickness skin biopsies. Expression of CRF was more pronounced in less differentiated keratinocytes, which corresponded to the detection of CRF immunoreactivity preferentially in the stratum basale. POMC expression was enhanced in more differentiated keratinocytes, which corresponded to detection of ACTH immunoreactivity, predominantly in the stratum spinosum and stratum granulosum. Expression of urocortins was also affected by induction of HPEKp differentiation. Immunohistochemical studies showed high prevalence of CRFR1 in well differentiated keratinocytes, while smaller keratinocytes showed predominantly CRFR2 immunoreactivity. MC2R mRNA levels were elevated from days 4 to 8 of in vitro incubation, while MC2R immunoreactivity was the highest in the upper layers of epidermis. Similar changes in mRNA/protein levels of sHPA elements were observed in HPEKp keratinocytes treated with calcium. Summarizing, preferential expression of CRF and POMC (ACTH) by populations of keratinocytes on different stage of differentiation resembles organization of central HPA axis suggesting their distinct role in physiology and pathology of the epidermis. (C) 2016 Wiley Periodicals, Inc.
Lifetime stress and war exposure timing may predict methylation changes atNR3C1based on a pilot study in a warrior cohort in asmall-scalesociety in Kenya
AMERICAN JOURNAL OF HUMAN BIOLOGY
Authors: Straight, Bilinda; Fisher, Georgiana; Needham, Belinda L.; Naugle, Amy; Olungah, Charles; Wanitjirattikal, Puntipa; Root, Cecilia; Farman, Jen; Barkman, Todd; Lalancette, Claudia
Abstract
Objectives Candidate gene methylation studies of NR3C1 have identified associations with psychosocial adversity, including war trauma. This pilot study (sample sizes from 22 to 45 for primary analyses) examined NR3C1 methylation in a group of Kenyan pastoralist young men in relation to culturally relevant traumatic experiences, including participation in coalitional lethal gun violence. Methods Adolescent and young adult Samburu men ("warriors") were recruited for participation. DNA was obtained from whole saliva and methylation analyses performed using mass spectrometry. We performed a data reduction of variables from a standardized instrument of lifetime stress using a factor analysis and we assessed the association between the extracted factors with culturally relevant and cross-culturally comparative experiences. Results Cumulative lifetime trauma exposure and forms of violence to which warriors are particularly susceptible were associated with DNA methylation changes in the NR3C1 1(F)promoter region but not in the NR3C1 1(D)promoter region. However, sensitivity analyses revealed significant associations between individual CpG sites in both regions and cumulative stress exposures, war exposure timing, and war fatalities. Conclusions This study supports the importance of NR3C1 methylation changes in response to challenging life circumstances, including in a global south cultural context that contrasts in notable ways from global north contexts and from the starkly tragic examples of the Rwandan genocide and war-associated rape explored in recent studies. Timing of traumatic exposure and culturally salient means to measure enduring symptoms of trauma remain important considerations for DNA methylation studies.