Alleviation of depression-like behavior in a cystic fibrosis mouse model by Hdac6 depletion

Abstract

Cystic fibrosis (CF) patients experience heightened levels of anxiety and depression. Stress from dealing with chronic disease and rigorous treatment regimens certainly are primary contributors to these outcomes. We previously have demonstrated that microtubule alterations in CF are linked to a number of CF phenotypes including growth regulation and inflammatory responses to airway bacterial challenge. Deletion of histone deactelyase 6 (HDAC6), a cytosolic deacetylase that regulates tubulin acetylation, in CF mice restores growth and inflammatory phenotypes to wild type (WT) profiles. In this study, the hypothesis that Hdac6 depletion in CF mice would impact behaviors since Hda6 inhibition has been previously reported to have anti-depressive properties. Data demonstrate that CF mice exhibit reduced activity and reduced open arm time in an elevated plus maze test which can be consistent with anxiety-like behavior. CF mice also exhibit depression-like behaviors compared to WT mice in an age dependent manner. By eight weeks of age, CF mice exhibit significantly more immobile time in the tail-suspension test, however, Hdac6 depletion reverses the depressive phenotype. These data demonstrate that loss of CFTR function may predispose patients to experience depression and that this behavior is Hdac6 dependent.

Figure 1

Total distance traveled in elevated-plus maze. Total distance traveled (cm) in 4-week old (A) and 8-week old (D) grouped male and female wild type (WT), F508del/F508del (CF), Hdac6-/-(HDA), and CF/HDA (DKO) mice. Responses are separated to male (B) and female (C) 4-week old mice. (D) Movement traces generated by IdTracker are shown for WT, CF, HDA, and DKO mice. Significance determine by ANOVA with Newman–Kuels post-hoc test to compare groups; *p < 0.05 compared to WT control group. Replicates for each study are: (A) WT = 10, CF = 20, HDA = 20, DKO = 20; (B) WT = 7, CF = 11, HDA = 12, DKO = 11; (C) WT = 7, CF = 9, HDA = 9, DKO = 9; (D) WT = 15, CF = 17, HDA = 21, DKO = 15.

Figure 2

Open arm time in elevated-plus maze. Time spent in open-arm in 4-week old (A) and 8-week old (B) grouped male and female wild type (WT), F508del/F508del (CF), Hdac6-/- (HDA), and CF/HDA (DKO) mice. Significance determine by ANOVA with Newman–Kuels post-hoc test to compare groups; *p < 0.05 compared to WT control group, **p < 0.05 compared to CF test group. Replicates are 13 mice for each group at 4-weeks of age and n = 16 for each group at 16 weeks of age.

Figure 3

Total distance traveled in open field test. Total distance traveled (cm) in 4-week old (A) and 8-week old (B) grouped male and female wild type (WT), F508del/F508del (CF), Hdac6-/-(HDA), and CF/HDA (DKO) mice. (C) Movement traces generated by IdTracker are shown for WT, CF, HDA, and DKO mice. Significance determine by ANOVA with Newman–Kuels post-hoc test to compare groups; *p < 0.05 compared to WT control group. Replicates for each study are: (A) WT = 14, CF = 19, HDA = 18, DKO = 19; (B) WT = 15, CF = 17, HDA = 16, DKO = 9.

Figure 4

Open area traveling in open field test. Time spent in open-area in 4-week old (A) and 8-week old (D) grouped male and female wild type (WT), F508del/F508del (CF), Hdac6-/-(HDA), and CF/HDA (DKO) mice. Significance determine by ANOVA with Newman–Kuels post-hoc test to compare groups; *p < 0.05 compared to WT control group, **p < 0.05 compared to CF test group. Replicates for each study are: (A) WT = 14, CF = 19, HDA = 19, DKO = 20; (B) WT = 20, CF = 21, HDA = 18, DKO = 16.

Figure 5

Immobility time in tail suspension test. Time spent immobile (s) during tail suspension test in 4-week old (A) and 8-week old (B) grouped male and female wild type (WT), F508del/F508del (CF), Hdac6-/-(HDA), and CF/HDA (DKO) mice. Significance determine by ANOVA with Newman–Kuels post-hoc test to compare groups; *p < 0.05 compared to WT control group, **p < 0.05 compared to CF test group. Replicates for each study are: (A) WT = 14, CF = 19, HDA = 18, DKO = 18; (B) WT = 15, CF = 16, HDA = 18, DKO = 18.

Figure 6

Acetylated tubulin levels in the hypothalamus. Acetylated tubulin (Ac-Tub) levels were assessed in excised hypothalamus from F508del/F508del (CF) and CF/HDA (DKO) mice Western blot and compared to total tubulin (Tub) content. Data are reported as Relative Density (Ac-Tub/Tub). Significance determined by t-test, n = 7 for each group; *p = 0.02.