The Ocular Surface Phenotype ofMuc5acandMuc5bNull Mice

Abstract

Our results indicate that deleting either the Muc5ac or Muc5b gene is insufficient to create an observable dry eye phenotype on the ocular surface of these mice.

Generating minicorneal organoids from human induced pluripotent stem cells

“…S4Av). An earlier report has confirmed that goblet cell development is normal in Muc5ac −/− ; Muc5b −/− mice (Marko et al, 2014). Taken together, we believe that MUC2 and MUC5AC are the developing and mature conjunctival goblet cell markers, respectively.…”

Goblet cells of the conjunctiva: A review of recent findings

“…These data correlate with data on Muc5AC and 5B null mice in which no infection was noted at the ocular surface (Marko et al, 2014) and on data from Spdef null mice in which no infections were reported in the gut (Gregorieff et al, 2009);(Noah et al, 2010) or respiratory tree(Park et al, 2007); Chen et al, 2009) . Lack of infection in these experimental mice suggests that other components of the mucosal surface such as membrane-anchored mucins, and surface antimicrobials may be sufficient barriers to prevent infection.…”

“…High resolution transmission electron microscopy demonstrates a granule membrane and a “filamentous” substructure to the mucin granule content (Fig. 3B), which may reflect the packaging of the large secretory mucin glycoprotein, MUC5AC in humans (Inatomi et al, 1996), or Muc5ac or 5b in mice (Marko et al, 2014), within the granule. Packaging of the very large, heavily O-glycosylated mucins within the mucin granule is dependent on having a high concentration of multivalent cations within the granule (Perez-Vilar, 2007) and disruption of calcium levels in epithelia due to vitamin D receptor knockdown, alters goblet cell mucin levels and mucin granules in the conjunctiva of the mice (Paz et al, 2003).…”

“…Another secreted mucin MUC2 has been described as present in the conjunctival goblet cells, but the levels of this mucin are some 5900 fold less than that of MUC5AC (McKenzie et al, 2000). In mice by comparison, two populations of goblet cells are present in the conjunctiva, those that express Muc5AC, and a smaller population that express the secretory mucin Muc5B (Marko et al, 2014). Recent studies testing the function of these two mucins on mouse ocular surface were done using mice null for either Muc5AC or Muc5B.…”

“…Recent studies testing the function of these two mucins on mouse ocular surface were done using mice null for either Muc5AC or Muc5B. No discernible phenotype was noted in either mouse, however there was a significant upregulation of Muc5b in the Muc5AC null mice, so in neither mouse was there a complete lack of secreted mucin making assessment of specific mucin difficult (Marko et al, 2014). These data also suggest that Muc5AC and Muc5b serve the same function at the mouse ocular surface.…”