The potency of the fs260 connexin43 mutant to impair keratinocyte differentiation is distinct from other disease-linked connexin43 mutants

Although there are currently 62 mutants of Cx43 (connexin43) that can cause ODDD (oculodentodigital dysplasia), only two mutants have also been reported to cause palmar plantar hyperkeratosis. To determine how mutants of Cx43 can lead to this skin disease, REKs (rat epidermal keratinocytes) were engineered to express an ODDD-associated Cx43 mutant always linked to skin disease (fs260), an ODDD-linked Cx43 mutant which has been reported to sometimes cause skin disease (fs230), Cx43 mutants which cause ODDD only (G21R, G138R), a mouse Cx43 mutant linked to ODDD (G60S), a non-disease-linked truncated Cx43 mutant that is trapped in the endoplasmic reticulum (Δ244*) or full-length Cx43. When grown in organotypic cultures, of all the mutants investigated, only the fs260-expressing REKs consistently developed a thinner stratum corneum and expressed lower levels of Cx43, Cx26 and loricrin in comparison with REKs overexpressing wild-type Cx43. REKs expressing the fs260 mutant also developed a larger organotypic vital layer after acetone-induced injury and exhibited characteristics of parakeratosis. Collectively, our results suggest that the increased skin disease burden exhibited in ODDD patients harbouring the fs260 mutant is probably due to multiple additive effects cause by the mutant during epidermal differentiation.

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Terminal differentiation in keratinocytes involves positive as well as negative regulation by retinoic acid receptors and retinoid X receptors at retinoid response elements

Molecular and Cellular Biology ◽

10.1128/mcb.12.11.4862-4871.1992 ◽

1992 ◽

Vol 12 (11) ◽

pp. 4862-4871

Author(s):

B J Aneskievich ◽

E Fuchs

Keyword(s):

Retinoic Acid ◽

Terminal Differentiation ◽

Cell Types ◽

Epidermal Differentiation ◽

Retinoic Acid Receptors ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Retinoid X Receptors ◽

Response Elements ◽

X Receptors

Terminal differentiation of epidermal keratinocytes is inhibited by 1 microM retinoic acid, a concentration which induces differentiation in a number of cell types, including F9 teratocarcinoma cells. The molecular basis for these opposing retinoid responses is unknown, although retinoic acid receptors (RARs) and retinoid X receptors (RXRs) have been detected in both cell types. When F9 cells are stably transfected with a truncated RAR alpha lacking the E/F domain necessary for ligand binding and RAR/RXR dimerization, action at retinoid response elements is suppressed and cells produce a retinoic acid-resistant phenotype; i.e., they are blocked in differentiation (A. S. Espeseth, S. P. Murphy, and E. Linney, Genes Dev. 3:1647-1656, 1989). If retinoid receptors influence epidermal differentiation only in a negative fashion, then suppression of transactivation at retinoid response elements would be expected to enhance, rather than block, keratinocyte differentiation. In this study, we show that surprisingly, even though constitutive expression of an analogous truncated RAR gamma in keratinocytes specifically suppressed transactivation at retinoid response elements, keratinocytes were blocked, rather than enhanced, in their ability to undergo morphological and biochemical features of differentiation. These findings demonstrate a direct and hitherto unrecognized role for RARs and RXRs in positively as well as negatively regulating epidermal differentiation. Additionally, our studies extend those of Espeseth et al. (Genes Dev. 3:1647-1656, 1989), indicating a novel RAR function independent of the E/F domain.

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The role of cathepsin E in terminal differentiation of keratinocytes

Biological Chemistry ◽

10.1515/bc.2011.060 ◽

2011 ◽

Vol 392 (6) ◽

Cited By ~ 8

Author(s):

Tomoyo Kawakubo ◽

Atsushi Yasukochi ◽

Kuniaki Okamoto ◽

Yoshiko Okamoto ◽

Seiji Nakamura ◽

...

Keyword(s):

Hair Follicle ◽

Primary Cultures ◽

Terminal Differentiation ◽

Epidermal Differentiation ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Marker Genes ◽

Differentiation Markers ◽

Cathepsin E

Abstract Cathepsin E (CatE) is predominantly expressed in the rapidly regenerating gastric mucosal cells and epidermal keratinocytes, in addition to the immune system cells. However, the role of CatE in these cells remains unclear. Here we report a crucial role of CatE in keratinocyte terminal differentiation. CatE deficiency in mice induces abnormal keratinocyte differentiation in the epidermis and hair follicle, characterized by the significant expansion of corium and the reduction of subcutaneous tissue and hair follicle. In a model of skin papillomas formed in three different genotypes of syngeneic mice, CatE deficiency results in significantly reduced expression and altered localization of the keratinocyte differentiation induced proteins, keratin 1 and loricrin. Involvement of CatE in the regulation of the expression of epidermal differentiation specific proteins was corroborated by in vitro studies with primary cultures of keratinocytes from the three different genotypes of mice. In wild-type keratinocytes after differentiation inducing stimuli, the CatE expression profile was compatible to those of the terminal differentiation marker genes tested. Overexpression of CatE in mice enhances the keratinocyte terminal differentiation process, whereas CatE deficiency results in delayed differentiation accompanying the reduced expression or the ectopic localization of the differentiation markers. Our findings suggest that in keratinocytes CatE is functionally linked to the expression of terminal differentiation markers, thereby regulating epidermis formation and homeostasis.

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A non-canonical lysosome biogenesis pathway generates Golgi-associated lysosomes during epidermal differentiation

10.1101/312033 ◽

2018 ◽

Author(s):

Sarmistha Mahanty ◽

Shruthi Shirur Dakappa ◽

Rezwan Shariff ◽

Saloni Patel ◽

Mruthyunjaya Mathapathi Swamy ◽

...

Keyword(s):

Cellular Differentiation ◽

Brefeldin A ◽

Epidermal Differentiation ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Differentiation Markers ◽

Human Epidermal Keratinocytes ◽

Lysosome Biogenesis ◽

Proteome Changes ◽

And Function

AbstractKeratinocytes maintain epidermis integrity and function including physical and antimicrobial barrier through cellular differentiation. This process is predicted to be controlled by calcium ion gradient and nutritional stress. Keratinocytes undergo proteome changes during differentiation, which enhances the intracellular organelle digestion to sustain the stress conditions. However, the molecular mechanism between epidermal differentiation and organelle homeostasis is poorly understood. Here, we used primary neonatal human epidermal keratinocytes to study the link between cellular differentiation, signaling pathways and organelle turnover. Upon addition of calcium chloride (2 mM) to the culture medium, keratinocytes increased their cell size and the expression of differentiation markers. Moreover, differentiated keratinocytes showed enhanced lysosome biogenesis that was dependent on ATF6-arm of UPR signaling but independent of mTOR-MiT/TFE transcription factors. Furthermore, chemical inhibition of mTOR has increased keratinocyte differentiation and relocalized the MiT/TFE TFs to the lysosome membranes, indicating that autophagy activation promotes the epidermal differentiation. Interestingly, differentiation of keratinocytes resulted in dispersal of fragmented Golgi and lysosomes, and the later organelles showed colocalization with Golgi-tethering proteins, suggesting that these lysosomes possibly originated from Golgi, hence named as Golgi-associated lysosomes (GALs). Consistent to this prediction, inhibition of Golgi function using brefeldin A completely abolished the formation of GALs and the keratinocyte differentiation. Thus, ER stress regulates the biogenesis of GALs, which maintains keratinocyte differentiation and epidermal homeostasis.

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Glycerol Improves Skin Lesion Development in the Imiquimod Mouse Model of Psoriasis: Experimental Confirmation of Anecdotal Reports from Patients with Psoriasis

International Journal of Molecular Sciences ◽

10.3390/ijms22168749 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8749

Author(s):

Vivek Choudhary ◽

Ismail Kaddour-Djebbar ◽

Victoria E. Custer ◽

Rawipan Uaratanawong ◽

Xunsheng Chen ◽

...

Keyword(s):

Mouse Model ◽

Knockout Mice ◽

Severity Index ◽

Skin Lesions ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Wild Type ◽

Lesion Development ◽

Beneficial Effects ◽

National Psoriasis Foundation

Glycerol is used in many skin care products because it improves skin function. Anecdotal reports by patients on the National Psoriasis Foundation website also suggest that glycerol may be helpful for the treatment of psoriasis, although to date no experimental data confirm this idea. Glycerol entry into epidermal keratinocytes is facilitated by aquaglyceroporins like aquaporin-3 (AQP3), and its conversion to phosphatidylglycerol, a lipid messenger that promotes keratinocyte differentiation, requires the lipid-metabolizing enzyme phospholipase-D2 (PLD2). To evaluate whether glycerol inhibits inflammation and psoriasiform lesion development in the imiquimod (IMQ)-induced mouse model of psoriasis, glycerol’s effect on psoriasiform skin lesions was determined in IMQ-treated wild-type and PLD2 knockout mice, with glycerol provided either in drinking water or applied topically. Psoriasis area and severity index, ear thickness and ear biopsy weight, epidermal thickness, and inflammatory markers were quantified. Topical and oral glycerol ameliorated psoriasiform lesion development in wild-type mice. Topical glycerol appeared to act as an emollient to induce beneficial effects, since even in PLD2 knockout mice topical glycerol application improved skin lesions. In contrast, the beneficial effects of oral glycerol required PLD2, with no improvement in psoriasiform lesions observed in PLD2 knockout mice. Our findings suggest that the ability of oral glycerol to improve psoriasiform lesions requires its PLD2-mediated conversion to phosphatidylglycerol, consistent with our previous report that phosphatidylglycerol itself improves psoriasiform lesions in this model. Our data also support anecdotal evidence that glycerol can ameliorate psoriasis symptoms and therefore might be a useful therapy alone or in conjunction with other treatments.

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Terminal differentiation in keratinocytes involves positive as well as negative regulation by retinoic acid receptors and retinoid X receptors at retinoid response elements.

Molecular and Cellular Biology ◽

10.1128/mcb.12.11.4862 ◽

1992 ◽

Vol 12 (11) ◽

pp. 4862-4871 ◽

Cited By ~ 32

Author(s):

B J Aneskievich ◽

E Fuchs

Keyword(s):

Retinoic Acid ◽

Terminal Differentiation ◽

Cell Types ◽

Epidermal Differentiation ◽

Retinoic Acid Receptors ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Retinoid X Receptors ◽

Response Elements ◽

X Receptors

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Single-cell transcriptomics defines keratinocyte differentiation in avian scutate scales

Scientific Reports ◽

10.1038/s41598-021-04082-1 ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Julia Lachner ◽

Florian Ehrlich ◽

Matthias Wielscher ◽

Matthias Farlik ◽

Marcela Hermann ◽

...

Keyword(s):

Gene Expression ◽

Single Cell ◽

Terminal Differentiation ◽

Epidermal Differentiation ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Scale Type ◽

Epidermal Differentiation Complex ◽

Evolutionarily Conserved ◽

Beta Proteins

AbstractThe growth of skin appendages, such as hair, feathers and scales, depends on terminal differentiation of epidermal keratinocytes. Here, we investigated keratinocyte differentiation in avian scutate scales. Cells were isolated from the skin on the legs of 1-day old chicks and subjected to single-cell transcriptomics. We identified two distinct populations of differentiated keratinocytes. The first population was characterized by mRNAs encoding cysteine-rich keratins and corneous beta-proteins (CBPs), also known as beta-keratins, of the scale type, indicating that these cells form hard scales. The second population of differentiated keratinocytes contained mRNAs encoding cysteine-poor keratins and keratinocyte-type CBPs, suggesting that these cells form the soft interscale epidermis. We raised an antibody against keratin 9-like cysteine-rich 2 (KRT9LC2), which is encoded by an mRNA enriched in the first keratinocyte population. Immunostaining confirmed expression of KRT9LC2 in the suprabasal epidermal layers of scutate scales but not in interscale epidermis. Keratinocyte differentiation in chicken leg skin resembled that in human skin with regard to the transcriptional upregulation of epidermal differentiation complex genes and genes involved in lipid metabolism and transport. In conclusion, this study defines gene expression programs that build scutate scales and interscale epidermis of birds and reveals evolutionarily conserved keratinocyte differentiation genes.

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Microrna-184 is Induced by Store-Operated Calcium Entry and Regulates Early Keratinocyte Differentiation

10.1101/319541 ◽

2018 ◽

Cited By ~ 1

Author(s):

Adam Richardson ◽

Andrew Powell ◽

Darren W. Sexton ◽

Jason L. Parsons ◽

Nicholas J. Reynolds ◽

...

Keyword(s):

Cyclin E ◽

Fold Increase ◽

Epidermal Differentiation ◽

Keratinocyte Differentiation ◽

Epidermal Keratinocytes ◽

Dependent Manner ◽

Dna Double Strand Breaks ◽

Dihydroxyvitamin D3 ◽

Keratinocyte Proliferation ◽

Store Operated Calcium Entry

ABSTRACTExtracellular calcium (Ca2+) and store-operated Ca2+ entry (SOCE) govern homeostasis in the mammalian epidermis. Multiple microRNAs (miRNA) also regulate epidermal differentiation, and raised external Ca2+ modulates the expression of several such miRNAs in keratinocytes. However, little is known about the regulation of miR-184 in keratinocytes or the roles of miR-184 in keratinocyte differentiation. Here we report exogenous Ca2+ stimulates miR-184 expression in primary epidermal keratinocytes and that this occurs in a SOCE-dependent manner. Levels of miR-184 were raised by about 30-fold after exposure to 1.5 mM Ca2+ for 5 days. In contrast, neither phorbol ester nor 1, 25-dihydroxyvitamin D3 had any effect on miR-184 levels. Pharmacologic and genetic inhibitors of SOCE abrogated Ca2+-dependent miR-184 induction by 70% or more. Ectopic miR-184 inhibited keratinocyte proliferation and led to a 4-fold increase in the expression of involucrin, a marker of early keratinocyte differentiation. Exogenous miR-184 also triggered a 3-fold rise in levels of cyclin E and doubled the levels of γH2AX, a marker of DNA double strand breaks. The p21 cyclin-dependent kinase (CDK) inhibitor, which supports keratinocyte growth arrest, was also induced by miR-184. Together our findings point to a SOCE:miR-184 pathway that targets a cyclin E/DNA damage regulatory node to facilitate keratinocyte differentiation.

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EGFR inhibitors switch keratinocytes from a proliferative to a differentiative phenotype affecting epidermal development and barrier function

BMC Cancer ◽

10.1186/s12885-020-07685-5 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Nicolas Joly-Tonetti ◽

Thomas Ondet ◽

Mario Monshouwer ◽

Georgios N. Stamatas

Keyword(s):

Growth Factor ◽

Barrier Function ◽

Kinase Inhibitors ◽

Treatment Protocol ◽

Growth Factor Receptor ◽

Skin Barrier ◽

Keratinocyte Differentiation ◽

Skin Barrier Function ◽

Epidermal Keratinocytes ◽

Epidermal Structure

Abstract Background Cutaneous adverse drug reactions (CADR) associated with oncology therapy involve 45–100% of patients receiving kinase inhibitors. Such adverse reactions may include skin inflammation, infection, pruritus and dryness, symptoms that can significantly affect the patient’s quality of life. To prevent severe skin damages dose adjustment or drug discontinuation is often required, interfering with the prescribed oncology treatment protocol. This is particularly the case of Epidermal Growth Factor Receptor inhibitors (EGFRi) targeting carcinomas. Since the EGFR pathway is pivotal for epidermal keratinocytes, it is reasonable to hypothesize that EGFRi also affect these cells and therefore interfere with the epidermal structure formation and skin barrier function. Methods To test this hypothesis, the effects of EGFRi and Vascular Endothelial Growth Factor Receptor inhibitors (VEGFRi) at therapeutically relevant concentrations (3, 10, 30, 100 nM) were assessed on proliferation and differentiation markers of human keratinocytes in a novel 3D micro-epidermis tissue culture model. Results EGFRi directly affect basal keratinocyte growth, leading to tissue size reduction and switching keratinocytes from a proliferative to a differentiative phenotype, as evidenced by decreased Ki67 staining and increased filaggrin, desmoglein-1 and involucrin expression compared to control. These effects lead to skin barrier impairment, which can be observed in a reconstructed human epidermis model showing a decrease in trans-epidermal water loss rates. On the other hand, pan-kinase inhibitors mainly targeting VEGFR barely affect keratinocyte differentiation and rather promote a proliferative phenotype. Conclusions This study contributes to the mechanistic understanding of the clinically observed CADR during therapy with EGFRi. These in vitro results suggest a specific mode of action of EGFRi by directly affecting keratinocyte growth and barrier function.

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Conversion of secretory proteins into membrane proteins by fusing with a glycosylphosphatidylinositol anchor signal of alkaline phosphatase

Biochemical Journal ◽

10.1042/bj3010577 ◽

1994 ◽

Vol 301 (2) ◽

pp. 577-583 ◽

Cited By ~ 8

Author(s):

K Oda ◽

J Cheng ◽

T Saku ◽

N Takami ◽

M Sohda ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Endoplasmic Reticulum ◽

Aspartic Acid ◽

Chimeric Protein ◽

Attachment Site ◽

In Vitro Translation ◽

Placental Alkaline Phosphatase ◽

Wild Type ◽

Aspartic Acid Residue

Placental alkaline phosphatase (PLAP) is initially synthesized as a precursor (proPLAP) with a C-terminal extension. We constructed a recombinant cDNA which encodes a chimeric protein (alpha GL-PLAP) comprising rat alpha 2u-globulin (alpha GL) and the C-terminal extension of PLAP. Two molecular species (25 kDa and 22 kDa) were expressed in the COS-1 cell transfected with the cDNA for alpha GL-PLAP. Only the 22 kDa form was labelled with both [3H]stearic acid and [3H]ethanolamine. Upon digestion with phosphatidylinositol-specific phospholipase C the 22 kDa form was released into the medium, indicating that this form is anchored on the cell surface via glycosylphosphatidylinositol (GPI). A specific IgG raised against a C-terminal nonapeptide of proPLAP precipitated the 25 kDa form but not the 22 kDa form, suggesting that the 25 kDa form is a precursor retaining the C-terminal propeptide. When a mutant alpha GL-PLAP, in which the aspartic acid residue is replaced with tryptophan at a putative cleavage/attachment site, was expressed in COS-1 cells, the 25 kDa precursor was the only form found inside the cell and retained in the endoplasmic reticulum, as judged by immunofluorescence microscopy. In vitro translation programmed with mRNAs coding for the wild-type and mutant forms of alpha GL-PLAP demonstrated that the C-terminal propeptide was cleaved from the wild-type chimeric protein, but not from the mutant one. This gave rise to the 22 kDa form attached with a GPI anchor, suggesting that GPI is covalently linked to the aspartic acid residue (Asp159) of alpha GL-PLAP. Taken together, these results indicate that the C-terminal propeptide of PLAP functions as a signal to render alpha GL a GPI-linked membrane protein in vitro and in vivo in cultured cells, and that the chimeric protein constructed in this study may be useful for elucidating the mechanism underlying the cleavage of the propeptide and attachment of GPI, which occur in the endoplasmic reticulum.

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Herpes Simplex Virus 1 UL34 Protein Regulates the Global Architecture of the Endoplasmic Reticulum in Infected Cells

Journal of Virology ◽

10.1128/jvi.00271-17 ◽

2017 ◽

Vol 91 (12) ◽

Cited By ~ 10

Author(s):

Fumio Maeda ◽

Jun Arii ◽

Yoshitaka Hirohata ◽

Yuhei Maruzuru ◽

Naoto Koyanagi ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Null Mutation ◽

Wild Type ◽

Herpes Simplex Virus 1 ◽

Nuclear Egress ◽

Infected Cells ◽

Simplex Virus ◽

Hsv 1

ABSTRACT Upon herpes simplex virus 1 (HSV-1) infection, the CD98 heavy chain (CD98hc) is redistributed around the nuclear membrane (NM), where it promotes viral de-envelopment during the nuclear egress of nucleocapsids. In this study, we attempted to identify the factor(s) involved in CD98hc accumulation and demonstrated the following: (i) the null mutation of HSV-1 UL34 caused specific dispersion throughout the cytoplasm of CD98hc and the HSV-1 de-envelopment regulators, glycoproteins B and H (gB and gH); (ii) as observed with CD98hc, gB, and gH, wild-type HSV-1 infection caused redistribution of the endoplasmic reticulum (ER) markers calnexin and ERp57 around the NM, whereas the UL34-null mutation caused cytoplasmic dispersion of these markers; (iii) the ER markers colocalized efficiently with CD98hc, gB, and gH in the presence and absence of UL34 in HSV-1-infected cells; (iv) at the ultrastructural level, wild-type HSV-1 infection caused ER compression around the NM, whereas the UL34-null mutation caused cytoplasmic dispersion of the ER; and (v) the UL34-null mutation significantly decreased the colocalization efficiency of lamin protein markers of the NM with CD98hc and gB. Collectively, these results indicate that HSV-1 infection causes redistribution of the ER around the NM, with resulting accumulation of ER-associated CD98hc, gB, and gH around the NM and that UL34 is required for ER redistribution, as well as for efficient recruitment to the NM of the ER-associated de-envelopment factors. Our study suggests that HSV-1 induces remodeling of the global ER architecture for recruitment of regulators mediating viral nuclear egress to the NM. IMPORTANCE The ER is an important cellular organelle that exists as a complex network extending throughout the cytoplasm. Although viruses often remodel the ER to facilitate viral replication, information on the effects of herpesvirus infections on ER morphological integrity is limited. Here, we showed that HSV-1 infection led to compression of the global ER architecture around the NM, resulting in accumulation of ER-associated regulators associated with nuclear egress of HSV-1 nucleocapsids. We also identified HSV-1 UL34 as a viral factor that mediated ER remodeling. Furthermore, we demonstrated that UL34 was required for efficient targeting of these regulators to the NM. To our knowledge, this is the first report showing that a herpesvirus remodels ER global architecture. Our study also provides insight into the mechanism by which the regulators for HSV-1 nuclear egress are recruited to the NM, where this viral event occurs.

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