Fig 1.
21 month old Dusp1 KO mice show similar cartilage damage as controls.
DUSP1 KO and WT control animals were aged to 21 months and right knees were evaluated for cartilage damage following OARSI recommended guidelines. (A-B) Representative toluidine blue stained frontal knee section images of the lateral (Lat.) and medial (Med.) femur (F) and tibia (T) of (A) female (n = 8) and (B) male (n = 5) mice, least damaged (left) and most damage (right), wild type controls (WT, top) and DUSP1 knockout (KO, bottom). Lesion (red arrowheads) location patterns and size were similar between WT and KO groups. Scale bars = 100 μm. (C-D) Total OARSI cartilage degeneration scores across the lateral tibial plateau (LTP), lateral femoral condyle (LFC), medial tibial plateau (MTP), medial femoral condyle (MFC), and cumulative joint score (Total Joint) of (C) female (n = 8) and (D) male (n = 5) WT and KO mice. OARSI scores did not show statistically significant differences between WT and KO groups when analyzed by Kruskal-Wallis with Dunn's multiple comparison test. Error bars are shown as mean ± SEM.
Fig 2.
Dusp1 KO mice show similar articular cartilage thickness when compared to controls.
Measurements from the subchondral bone to the intact articular cartilage surface were made at 3 points across the lateral tibial plateau (LTP), lateral femoral condyle (LFC), medial tibial plateau (MTP) or medial femoral condyle (MFC) and averaged. (A) Female (n = 8) and (B) male (n = 5) DUSP1 KO mice do not show statistically significantly different articular cartilage thickness when compared to WT controls. Analyzed by Kruskal-Wallis with Dunn's multiple comparison test. Error bars are shown as mean ± SEM. (C) Example diagram demonstrating approximate sites of articular cartilage measurements indicated by dashed red lines. F = femur, T = tibia, Lat. = lateral, Med. = medial.
Fig 3.
Cartilage matrix neoepitope immunostaining shows similar intensity and localization in Dusp1 KO and WT control mice.
(A) Female (n = 6) and (B) male (n = 5) representative medial femur (F) and tibia (T) joint sections were immunostained for: DIPEN (Top, MMP cleaved aggrecan neoepitope), TEGE (Middle, aggrecanase cleaved aggrecan neoepitope), and C1,2C (Bottom, MMP cleaved collagen II/I). Regions of pericellular and extracellular matrix (ECM) staining are indicated by the black arrowheads. Scale bars = 100 μm.
Fig 4.
Decrease in cartilage anabolism marker SOX9 in Dusp1 KO mice.
(A) Representative phosphoERK (phERK) immunostained female (n = 6) lateral (Lat.) femur (F) and tibia (T) joint images show similar cellular staining (arrowheads) in DUSP1 KO and WT control mice. (B) Representative MMP13 immunostained female (n = 6) medial (Med.) femur (F) and tibia (T) joint images show similar pericellular and matrix staining (arrowheads) in DUSP1 KO and WT control mice. (C) Representative SOX9 immunostained female (n = 6) medial femur (F) and tibia (T) joint images show decreased staining intensity and positive cells (arrowheads) in Dusp1 KO mice when compared to WT controls. All scale bars = 100 μm. (D) The number of SOX9 positive cells in female Dusp1 KO mice was decreased but not statistically significantly different (p = 0.095) from WT controls. Data analyzed using Mann-Whitney test. Error bars are shown as mean ± SEM.
Fig 5.
Gait patterns are not different in Dusp1 KO mice at 21 months of age.
Gait patterns of Dusp1 KO and WT control mice were measured using the Noldus CatWalk apparatus prior to sacrifice at 21 months of age. (A) Female (n = 5) and (B) male (n = 5) stride length (distance between individual hind paw prints during gait) were not statistically different between WT and KO mice. (C) Female (n = 5) and (D) male (n = 5) duty cycle (% of time in stand phase of walk cycle) was also not statistically different between WT and KO mice. Data analyzed using Mann-Whitney test. Error bars are shown as mean ± SEM.