Transient elevation of cytoplasmic calcium ion concentration at a single cell level precedes morphological changes of epidermal keratinocytes during cornification

Murata, Takaho; Honda, Tetsuya; Egawa, Gyohei; Yamamoto, Yasuo; Ichijo, Ryo; Toyoshima, Fumiko; Dainichi, Teruki; Kabashima, Kenji

doi:10.1038/s41598-018-24899-7

Cited by 29 publications

(24 citation statements)

References 42 publications

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“…In either case, this is the first example of visualizing such intracellular morphological changes ex vivo . In previous studies conducted by a labelling method using a 3D skin model and mice, change in morphology of nuclei in the last moment of the enucleation process was captured on a time scale within 60 minutes 43,44 . The time scale of morphological changes in the nucleus we captured do not seem to contradict these previous studies.…”

Section: Discussionmentioning

confidence: 99%

Label-free stimulated Raman scattering microscopy visualizes changes in intracellular morphology during human epidermal keratinocyte differentiation

Egawa

Iwanaga

Hosoi

et al. 2019

Sci Rep

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Epidermal keratinocyte (KC) differentiation, which involves the process from proliferation to cell death for shedding the outermost layer of skin, is crucial for the barrier function of skin. Therefore, in dermatology, it is important to elucidate the epidermal KC differentiation process to evaluate the symptom level of diseases and skin conditions. Previous dermatological studies used staining or labelling techniques for this purpose, but they have technological limitations for revealing the entire process of epidermal KC differentiation, especially when applied to humans. Here, we demonstrate label-free visualization of three-dimensional (3D) intracellular morphological changes of ex vivo human epidermis during epidermal KC differentiation using stimulated Raman scattering (SRS) microscopy. Specifically, we observed changes in nuclei during the initial enucleation process in which the nucleus is digested prior to flattening. Furthermore, we found holes left behind by improperly digested nuclei in the stratum corneum, suggesting abnormal differentiation. Our findings indicate the great potential of SRS microscopy for discrimination of the degree of epidermal KC differentiation.

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Section: Discussionmentioning

confidence: 99%

Label-free stimulated Raman scattering microscopy visualizes changes in intracellular morphology during human epidermal keratinocyte differentiation

Egawa

Iwanaga

Hosoi

et al. 2019

Sci Rep

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“…The development of the SC permeability barrier takes place on E16.5 from the dorsal-to-ventral aspects like a wave [32]. This final process of epidermal differentiation (keratinization), which leads to the abrupt specialized cell death in the SG1 [16], involves many biological changes such as rapid influx of intracellular calcium ion [145], disappearance of the TJ permeability barrier [146], or the degradation of organelles [13]. However, based on the structural "bricks and mortar" analogy [4], acquisition of the SC permeability barrier depends on the redox-based prompt cytoskeletal cross-linking (bricks) [10,27,147] and timely attachment of extruded LG content (mortar), resulting in an ordered lamellar structure [33,61].…”

Section: Immunoanatomy Of the Epithelium: It Is Not What It Is Made Omentioning

confidence: 99%

Loricrin: Past, Present, and Future

Ishitsuka

Roop

2020

IJMS

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The terminal differentiation of the epidermis is a complex physiological process. During the past few decades, medical genetics has shown that defects in the stratum corneum (SC) permeability barrier cause a myriad of pathological conditions, ranging from common dry skin to lethal ichthyoses. Contrarily, molecular phylogenetics has revealed that amniotes have acquired a specialized form of cytoprotection cornification that provides mechanical resilience to the SC. This superior biochemical property, along with desiccation tolerance, is attributable to the proper formation of the macromolecular protein-lipid complex termed cornified cell envelopes (CE). Cornification largely depends on the peculiar biochemical and biophysical properties of loricrin, which is a major CE component. Despite its quantitative significance, loricrin knockout (LKO) mice have revealed it to be dispensable for the SC permeability barrier. Nevertheless, LKO mice have brought us valuable lessons. It is also becoming evident that absent loricrin affects skin homeostasis more profoundly in many more aspects than previously expected. Through an extensive review of aggregate evidence, we discuss herein the functional significance of the thiol-rich protein loricrin from a biochemical, genetic, pathological, metabolic, or immunological aspect with some theoretical and speculative perspectives.

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“…Based on many previous studies, an elevated cytoplasmic calcium ion ([Ca 2+ ] i ) concentration has been thought to be a key factor for triggering cornification [35][36][37] . Indeed, a recent study using intravital mouse imaging demonstrated that the [Ca 2+ ] i was transiently elevated approximately 40 min before cornification 38 . Therefore, the series of morphological changes we observed can be estimated as a result of the elevation of [Ca 2+ ] i .…”

Section: Discussionmentioning

confidence: 99%

Live imaging of alterations in cellular morphology and organelles during cornification using an epidermal equivalent model

Ipponjima

Umino

Nagayama

et al. 2020

Sci Rep

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the stratum corneum plays a crucial role in epidermal barrier function. Various changes occur in granular cells at the uppermost stratum granulosum during cornification. To understand the temporal details of this process, we visualized the cell shape and organelles of cornifying keratinocytes in a living human epidermal equivalent model. three-dimensional time-lapse imaging with a two-photon microscope revealed that the granular cells did not simply flatten but first temporarily expanded in thickness just before flattening during cornification. Moreover, before expansion, intracellular vesicles abruptly stopped moving, and mitochondria were depolarized. When mitochondrial morphology and quantity were assessed, granular cells with fewer, mostly punctate mitochondria tended to transition to corneocytes. Several minutes after flattening, DNA leakage from the nucleus was visualized. We also observed extension of the cell-flattening time induced by the suppression of filaggrin expression. Overall, we successfully visualized the time-course of cornification, which describes temporal relationships between alterations in the transition from granular cells to corneocytes. The human epidermis is a heterogeneous, multilayered structure constructed from keratinocytes 1. All keratinocytes are originally produced at the lowest layer of the epidermis, the stratum basale (SB), following which they move towards the skin surface while differentiating through the stratum spinosum (SS) and stratum granulosum (SG) and finally transform into corneocytes at the border between the SG and the most outer layer, the stratum corneum (SC). Due to the robust hydrophobic features of the SC and tight junctions that form at the second layer of the SG, these factors play a crucial role in protection against physical damage and harmful factors outside the body as well as the prevention of water loss from inside the body 2-4. The terminal differentiation of the uppermost granular cells to corneocytes, the cells of the SC, is called cornification, which is a kind of programmed cell death. During cornification, a variety of phenomena occur in granular cells 3. One of the most obvious changes is in their thickness. Corneocytes are very thin with a thickness of approximately 0.2-0.5 μm 5. Furthermore, corneocytes do not contain nuclei and other organelles but rather are filled with densely packed keratin filaments throughout their cytoplasm 3,6. The condensation of keratin filaments is induced by interaction with filaggrin monomers 7,8. At the cell periphery, the cornified envelope, a structure consisting of various cross-linked intracellular proteins such as involucrin and loricrin, is formed 9. Adjacent corneocytes are interconnected by corneodesmosomes, which are modified desmosomes, and their intercellular space is filled with lipids 2. Several recent reports have elucidated that autophagy is involved in the elimination of nuclei and mitochondria during terminal differentiation 10,11. It has also been reported that DNA is degraded by both DNase1L2 ...

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Transient elevation of cytoplasmic calcium ion concentration at a single cell level precedes morphological changes of epidermal keratinocytes during cornification

Cited by 29 publications

References 42 publications

Label-free stimulated Raman scattering microscopy visualizes changes in intracellular morphology during human epidermal keratinocyte differentiation

Label-free stimulated Raman scattering microscopy visualizes changes in intracellular morphology during human epidermal keratinocyte differentiation

Loricrin: Past, Present, and Future

Live imaging of alterations in cellular morphology and organelles during cornification using an epidermal equivalent model

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