Table 1.

Intrinsic regulators of HFSCs homeostasis. Notable TFs and proteins involved in intrinsic regulation of HFSCs homeostasis and their sources are listed. Proteins found in the top half of the table in bold letters indicate regulators that have been studied in recent 5 years, while those listed in the bottom half indicate notable HFSC regulators from earlier studies. denotes expressions observed during development.

Proteins	Expression location	HC stage	Function	Associated signaling pathway	Targets	Source
NFI	Bulge, hair germ, ORS	Telo, Ana	SC Identity & lineage specification	Chromatin remodeling	SC super-enhancers	Adam et al., 2020
Myb	bulge, ORS	Telo, Ana	SC proliferation & differentiation	Bmp	HF-lineage genes	Veselá et al., 2014; Hu et al., 2019
Runx1	bulge, hair germ, ORS	All	SC activation & proliferation	Stat3, Wnt	p21, p15	Osorio et al., 2008; Osorio et al., 2011; Scheitz et al., 2012; Lee et al., 2013
Foxc1	bulge, IRS	All	SC quiescence	Bmp	Nfatc1, Bmp2	Wang et al„ 2016; Lay et al., 2016
Foxi3	hair germ	Telo	SC proliferation & bulge specification	Shh	HFSC genes	Shirokova et al., 2016
Gata6	hair germ, IRS	Telo, Ana	Proliferation & DNA damage protection	NF-kB	DNA damage repair genes	Wang et al., 2017; Krieger et al., 2018
Ovol2	bulge, hair germ	Telo, Ana	SC migration & proliferation	Ovol2-Zeb1	Zeb1	Haensel et al., 2019
Lgr4	bulge, hair germ, ORS, IRS	All	SC activation & proliferation	mTOR, Wnt, Bmp	R-spondin	Ren et al., 2020
Hes1	bulge, hair germ	Telo, Ana	HF growth	Shh	Gli1, Ptch1	Suen et al., 2020
Axin2	bulge	Telo, Ana	SC quiescence	Wnt	Dkks, Sfrp1	Lim et al., 2016
Sirt7	bulge, hair germ	Telo, Ana	SC activation	Bmp/Nfatc1	Nfatc1	Li et al., 2020
Msi2	bulge, hair germ, ORS, IRS	All	SC quiescence	Shh	Shh	Ma et al., 2017
Acer1	bulge	Ana?	Lineage specification	unspecified	unspecified	Lin et al., 2017; Liakath-Ali et al., 2016
Par3	unspecified	unspecified	Lineage specification	unspecified	unspecified	Liakath-Ali et al., 2016
Endoglin	unspecified	All	SC quiescence & activation	Wnt/β-catenin, Bmp	Bmp	Calvo-Sánchez et al., 2019
Lgr5	bulge, hair germ, ORS	All	SC proliferation & self-renewal; lineage specification	Wnt, Shh	R-spondin, HF-lineage genes	Jaks et al., 2008
Tcf3/4	bulge, hair germ, ORS	All	Lineage specification	Wnt/β-catenin	HF-lineage genes	Merrill et al., 2001; Lien et al., 2014
Lef1	hair germ, IRS	Ana	Lineage specification	Wnt/β-catenin, Notch	HF-lineage genes	Zhou et al., 1995; Merrill et al., 2001; Niemann et al., 2002; Zhang et al., 2013; Lien et al., 2014; Adam et al., 2018
Lhx2	bulge, hair germ, ORS	All	Bulge organization & maintenance	Wnt	HFSC genes, cytoskeletal & adhesion protein genes	Rhee et al., 2006; Folgueras et al., 2013; Mardaryev et al., 2011
Sox9	bulge, hair germ, ORS	All	Lineage specification	Tgfβ/Activin, Wnt, Bmp, Shh	HF-lineage genes	Vidal et al., 2005; Kadaja et al., 2014; Adam et al., 2015
Nfatc1	bulge	All	SC quiescence	Bmp	CDK4	Horsley et al., 2008
Ctip2	bulge, hair germ, ORS	All	SC quiescence & maintenance	Notch†, Egfr†	Nfatc1, Nhx2	Bhattacharya et al., 2015
Foxp1	bulge	All	SC quiescence	p19/p53	Fgf18, p57	Leishman et al., 2013; Zhao et al., 2015
p63	bulge, hair germ, ORS	Telo	Lineage specification	Wnt/β-catenin†, Shh†	Wnt5a†, Tcf3/Tcf4†, Lef1†	Romano et al., 2010
Gab1	bulge, hair germ, ORS	Telo, Ana	SC quiescence & maintenance	Ras/Mapk	Mapk	Ozturk et al., 2015
Hopx	bulge, hair germ, ORS, IRS	All	unspecified	unspecified	unspecified	Takeda et al., 2013
aPKCλ	unspecified	unspecified	SC quiescence; lineage specification	unspecified	Bmp6, Fgf18	Niessen et al., 2013; Osada et al., 2015