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Muroy et al. Neuroimmunol Neuroinflammation 2020;7:166-82 Neuroimmunology
DOI: 10.20517/2347-8659.2020.16 and Neuroinflammation

Original Article Open Access

Phf15 - a novel transcriptional repressor regulating
inflammation in a mouse microglial cell line

Sandra E. Muroy , Greg A. Timblin , Marcela K. Preininger , Paulina Cedillo , Kaoru Saijo 1,2
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1 Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
2 Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA.
Correspondence to: Prof. Kaoru Saijo, Department of Molecular and Cell Biology, University of California, Berkeley, 439 Life
Sciences Addition, Berkeley, CA 94720, USA. E-mail: ksaijo@berkeley.edu
How to cite this article: Muroy SE, Timblin GA, Preininger MK, Cedillo P, Saijo K. Phf15 - a novel transcriptional repressor
regulating inflammation in mouse microglia cell line. Neuroimmunol Neuroinflammation 2020;7:166-82.
http://dx.doi.org/10.20517/2347-8659.2020.16

Received: 11 Feb 2020 Accepted: 14 Feb 2020 Available online: 17 Apr 2020
Science Editor: Andis Klegeris Copy Editor: Jing-Wen Zhang Production Editor: Tian Zhang

Abstract
Aim: Excessive microglial inflammation has emerged as a key player in mediating the effects of aging and
neurodegeneration on brain dysfunction. Thus, there is great interest in discovering transcriptional repressors that can
control this process. We aimed to examine whether Phf15 - one of the top differentially expressed genes in microglia
during aging in humans - could regulate transcription of proinflammatory mediators in microglia.

Methods: Real-time quantitative PCR was used to assess Phf15 mRNA expression in mouse brain during aging. Loss-
of-function [short hairpin RNA (shRNA) -mediated knockdown (KD) and CRISPR/Cas9-mediated knockout (KO) of
Phf15] and gain-of-function [retroviral overexpression (OE) of murine Phf15 cDNA] studies in a murine microglial cell
line (SIM-A9) followed by immune activation with lipopolysaccharide were used to determine the effect of Phf15 on
proinflammatory factor (Tnfα , IL-1β , and Nos2) mRNA expression. RNA sequencing was used to determine global
transcriptional changes after Phf15 knockout under basal conditions and after lipopolysaccharide stimulation.

Results: Phf15 expression increases in mouse brain during aging, similar to humans. KD, KO, and OE studies determined
that Phf15 represses mRNA expression levels of proinflammatory mediators such as Tnfα , IL-1β , and Nos2 . Global
transcriptional changes after Phf15 KO showed that Phf15 specifically represses genes related to the antiviral (type I
interferon) response and cytokine production in microglia.

Conclusion: We provide the first evidence that Phf15 is an important transcriptional repressor of microglial inflammation,
regulating the antiviral response and proinflammatory cytokine production. Importantly, Phf15 regulates both basal and
signal-dependent activation and controls the magnitude and duration of the microglial inflammatory response.

Keywords: Phf15, microglia, transcriptional repression, neuroinflammation

© The Author(s) 2020. Open Access This article is licensed under a Creative Commons Attribution 4.0
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