Science - 06.12.2019

A SC-driven secretome switch is required for
lymphatic remodeling
Angiopoietin-like (ANGPTL) proteins do not
bind to classical angiopoietin receptors, and
knowledge of these orphan ligands is still
scant ( 31 , 32 ). To address whetherAngptl7
down-regulation functions in HFSC activa-
tion, we engineered mice to harbor anAngptl7
transgene that is selectively doxycycline-
inducible in skin progenitors ( 33 ). We then

induced at telogen and examined the con-

sequences of maintaining ANGPTL7 through

early stages of the newly entered hair cycle (fig.

S10, A to E).

In contrast to the lymphatic–SC niche re-

modeling of normal HFs, lymphatic capillaries

remained tightly associated and the bulge re-

mained quiescent whenAngptl7was sustained

(Fig. 5A). Consistent with a nonautonomous

role for ANGPTL7 in controlling stemness ac-

tivity, recombinant ANGPTL7 did not appre-

ciably alter colony formation of HFSCs in vitro.

Rather, concomitant with sustained lym-

phatic efflux and drainage capacity, entry

into the hair cycle was markedly delayed (Fig.

5B and fig. S10, C to E). Because a role for

ANGPTL7 in angiogenesis had been suggested,

we looked for, but did not find, perturbations

in blood vessel density and coverage in our

Angptl7-induced skin (fig. S10E). ANGPTL7

Gur-Cohenet al.,Science 366 , 1218–1225 (2019) 6 December 2019 4of8

LYVE1 KRT24 P-CAD

Tel-Ana I Quiescence

Ana II-IIIProliferation

Ana IVQuiescence

Bu

Bu

Bu

Bu

Bu Bu

Bu

Bu

Bu

Bu

Bu

Bu

BuBu

30 μm

30 μm

30 μm

Bu

Surface rendering

15 μm

30 μm

30 μm

A

Reduced lymphatic draining during stem cell activation

600 μm

Tel-Ana I 600 μm

Ana II-III

OVA-Ax488

Brachial LN

Telogen

Ana II-III

KI67 LYVE1 KRT24

Tel-Ana IAna II -

III

Ana IV

0

50

100

150

% Bulge associated wit h

lymphatic capillaries

p < 0.0001

p = 0.0003

p = 0.03

L-Cap

L-Col

L-Cap

L-Col

L-Cap

L-Col

Tel-Ana I

Quiescence

Ana II-III

Proliferation

Ana IV

Quiescence

LYVE1 VEGFR3 DAPI

Telogen

Ana IIAna III

0

20

40

60

Lym ph ati c capillaries width (μ m)

p< 0.0001

30 μm 40 μm

LYVE1 P-CAD PROX1

Telogen -Ana I Ana II-III

Tel-Ana IAna II-III

0

20

40

60

PROX1

+ nuclei (per follic

le)

0

5

10

15

PRO

X1

+ nuclei

(associat

ed

with bulge SCs

)

p < 0.0001

Tel-Ana IAna II-III

(1)

(2)

Bu

HG

50 μm

Bu

HG

50 μm

Bu

50 μmTAC

B

C D

E

Tel-Ana IAna II-

III

Ana IVAna V

0

1

2

3

4

5

EB (OD/g tissue)

p = 0.001p = 0.0024

p = 0.0009

Tel

Ana II-III

0.0

5.0 10^9

1.0 10^10

1.5 10^10

OVA-Ax48

8 (A.U.)

p= 0.0008

30 μm

30 μm

LYVE1 KRT24 P-CAD DAPI

Fig. 3. HFSC–lymphatic associations are dynamic.(A) 3D imaging and
surface rendering of cleared skin tissue, demonstrating LYVE1+lymphatic
capillary dissociation from KRT24+bulge SCs during AnaII–III of the hair
cycle. P-CADhighcells are HFSC progeny. (B) Despite dissociating (empty
arrow for dissociation versus white arrow for association) from the SC niche,
lymphatic capillaries remain connected to their underlying collecting vessels
(LYVE1negVEGFR3+) during AnaII–III. Quantifications of temporal changes
in SC–capillary associations and lymphatic width (n= 5, 6 andn= 5 ,
one-way ANOVA; Tukey’s multiple comparisons test). TAC, transient
amplifying cells. (C) Capillary dissociation correlates with bulge SC self-
renewal (Ki67+). (D) PROX1+lymphatics dissociate from the bulge during
AnaII–III but do not disappear (1 indicates Prox1+capillaries, 2 indicates
Prox1+collecting;n= 3; two-tailed unpairedttest). (E) Reduced lymphatic
drainage capacity in AnaII–III, as measured by intradermal injections of Evans Blue (EB;n= 3, one-way ANOVA; Tukey’s multiple comparisons test) and OVA-Ax488
efflux to brachial lymph nodes (LN;n= 3 and 6 for Tel–AnaI and AnaII–III, respectively; two-tailed unpairedttest). OD, optical density.

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