Involucrin is an important precursor of the keratinocyte cornified envelope. In epidermis, expression of involucrin protein and mRNA is keratinocyte-specific and differentiation-dependent (i.e., expression is confined to the suprabasal layers). Our transgenic mouse and cell culture studies show that the human involucrin (hINV) gene upstream regulatory region is sufficient for this expression and that specific DNA elements in this region bindAPI, C/EBP and Spl transcription factors to drive expression. During the past funding period we identified a novelPKC, Ras, MEKK1, MEK3 and p388-ERKl/2 signaling cascade that regulates the activity and level of API, Spl and C/EBP transcription factors to increase involucrin gene expression. Although identifying this cascade represents a major step forward in our understanding of differentiation associated gene regulation, our understanding of this signal transduction cascade is far from complete. Having established the importance of this pathway, we now propose experiments designed to extend these findings. Our studies show that novel PKC isoforms, including PKC5, are the major activators of hINV gene expression in normal keratinocytes and that differentiation agents trigger tyrosine phosphorylation of PKC8 to regulate gene expression. However, the importance of PKC8 tyrosine phosphorylation in keratinocytes is complicated, controversial, and has not been thoroughly studied. Our first major goal is to identify the role of tyrosine phosphorylation of PKC8 on PKC8 activity, subcellular localization, and ability to regulate downstream signaling events. An important observation is that signal transduction in normal human keratinocytes converges at the MAPK level on p388. Our preliminary studies suggest that differential interaction of MEK3 and MEK6 with p38S may function to regulate the balance between keratinocyte differentiation and apoptosis. The second major goal of this study is to characterize the role of these kinases in regulating the balance between differentiation and apoptosis. In particular, we will focus on the role of PKC8, MEK3 and p388 in regulating keratinocyte differentiation. The overall goal of this proposal is to expand our knowledge regarding the molecular mechanisms that drive differentiation in keratinocytes. This work is particularly important, as this mitogen-activated protein kinase (MAPK) signaling cascade has been implicated in regulating keratinocyte survival, differentiation, death, and transformation. It is hoped that a better understand of this cascade will lead to new and effective therapies for epidermal disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR046494-10
Application #
7588739
Study Section
Arthritis, Connective Tissue and Skin Study Section (ACTS)
Program Officer
Baker, Carl
Project Start
2000-03-01
Project End
2011-03-31
Budget Start
2009-04-01
Budget End
2010-03-31
Support Year
10
Fiscal Year
2009
Total Cost
$183,177
Indirect Cost
Name
University of Maryland Baltimore
Department
Biochemistry
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Rorke, Ellen A; Adhikary, Gautam; Young, Christina A et al. (2015) Suppressing AP1 factor signaling in the suprabasal epidermis produces a keratoderma phenotype. J Invest Dermatol 135:170-180
Saha, Kamalika; Adhikary, Gautam; Kanade, Santosh R et al. (2014) p38? regulates p53 to control p21Cip1 expression in human epidermal keratinocytes. J Biol Chem 289:11443-53
Chew, Yap Ching; Adhikary, Gautam; Xu, Wen et al. (2013) Protein kinase C ? increases Kruppel-like factor 4 protein, which drives involucrin gene transcription in differentiating keratinocytes. J Biol Chem 288:17759-68
Han, Bingshe; Rorke, Ellen A; Adhikary, Gautam et al. (2012) Suppression of AP1 transcription factor function in keratinocyte suppresses differentiation. PLoS One 7:e36941
Chew, Yap Ching; Adhikary, Gautam; Wilson, Gerald M et al. (2012) Sulforaphane induction of p21(Cip1) cyclin-dependent kinase inhibitor expression requires p53 and Sp1 transcription factors and is p53-dependent. J Biol Chem 287:16168-78
Kanade, Santosh R; Eckert, Richard L (2012) Protein arginine methyltransferase 5 (PRMT5) signaling suppresses protein kinase C?- and p38?-dependent signaling and keratinocyte differentiation. J Biol Chem 287:7313-23
Chen, Cheng-Jueng; Wu, Bai-Yao; Tsao, Pai-In et al. (2011) Increased matriptase zymogen activation in inflammatory skin disorders. Am J Physiol Cell Physiol 300:C406-15
Chew, Yap Ching; Adhikary, Gautam; Wilson, Gerald M et al. (2011) Protein kinase C (PKC) delta suppresses keratinocyte proliferation by increasing p21(Cip1) level by a KLF4 transcription factor-dependent mechanism. J Biol Chem 286:28772-82
Adhikary, Gautam; Chew, Yap Ching; Reece, E Albert et al. (2010) PKC-delta and -eta, MEKK-1, MEK-6, MEK-3, and p38-delta are essential mediators of the response of normal human epidermal keratinocytes to differentiating agents. J Invest Dermatol 130:2017-30
Rorke, E A; Adhikary, G; Jans, R et al. (2010) AP1 factor inactivation in the suprabasal epidermis causes increased epidermal hyperproliferation and hyperkeratosis but reduced carcinogen-dependent tumor formation. Oncogene 29:5873-82

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