June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Hedgehog signaling promotes expansion of Meibomian Gland stem cells in vivo
Author Affiliations & Notes
  • Xuming Zhu
    Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
    Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Mingang Xu
    Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
    Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Marina Grachtchouk
    Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, Michigan, United States
    Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, United States
  • Andrzej A Dlugosz
    Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, Michigan, United States
    Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, United States
  • Sarah E Millar
    Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
    Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Footnotes
    Commercial Relationships   Xuming Zhu None; Mingang Xu None; Marina Grachtchouk None; Andrzej Dlugosz None; Sarah Millar None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 2270. doi:
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    • Get Citation

      Xuming Zhu, Mingang Xu, Marina Grachtchouk, Andrzej A Dlugosz, Sarah E Millar; Hedgehog signaling promotes expansion of Meibomian Gland stem cells in vivo. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2270.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Meibomian glands (MGs) are specialized sebaceous glands (SGs) in which meibocytes are constantly replenished through proliferation and differentiation of acinar basal stem cells (SCs). However, specific markers for self-renewing SCs of MG (MGSCs) are poorly defined, and the signals that control their activity are incompletely understood. The Hedgehog (HH)/GLI pathway controls proliferation and differentiation of rat MG epithelial cells in vitro, and GLI2 is highly expressed in acinar basal cells and differentiating meibocytes but is absent from fully differentiated meibocytes in vivo. We hypothesize that MGSCs express similar marker genes as SCs of hair follicle SGs (SGSCs), and that GLI2 regulates MG homeostasis by coordinating proliferation and differentiation of MGSCs.

Methods : To determine whether the hair follicle SGSC markers Lrig1 and Lgr6, and the ubiquitous Wnt target gene Axin2, label self-renewing MGSCs we performed short- and long-term lineage tracing experiments using Lrig1-CreERT2, Lgr6-CreERT2, and Axin2-CreERT2 mice carrying the Rosa26mTmG Cre reporter allele. To determine the effects of GLI2-mediated HH signaling on MGSCs we generated transgenic mice with forced expression of activated GLI2 (GLI2ΔN) in MG basal epithelial cells and carried out transcriptional profiling of laser captured MGs from control and GLI2ΔN-expressing mice. RNAscope and immunofluorescence were used to confirm RNA-seq results.

Results : Short-term lineage tracing data showed that Lrig1, Lgr6 and Axin2 label basal cells in MG ducts and acini. Long-term lineage tracing results showed that clones of labeled cells persist through multiple rounds of ductal and acinar renewal and give rise to differentiated progeny, identifying Lrig1+, Lgr6+ and Axin2+ ductal and acinar basal cells as self-renewing SCs. Forced expression of GLI2ΔN enhanced basal proliferation, caused expansion of Lrig1+ SCs, and lead to replacement of lipid-filled meibocytes by proliferative and poorly differentiated acinar cells. Transcriptional profiling of GLI2ΔN-expressing and control MGs revealed that forced GLI2ΔN expression caused greatly increased expression of Lrig1 and Lgr6 and suppressed expression of meibocyte differentiation genes.

Conclusions : (1) Lrig1+, Lgr6+ and Axin2+ mark self-renewing basal SCs that replenish MG acinar and ductal epithelium in vivo. (2) GLI2-mediated HH signaling promotes proliferation and inhibits differentiation of MGSCs.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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