A mouse gene family associated with a major submaxillary-gland glycoprotein

The genetic control of sialadenitis versus arthritis in a NOD.QxB10.Q F2 cross

The non-obese diabetic (NOD) mouse spontaneously develops diabetes and sialadenitis. The sialadenitis is characterized by histopathological changes in salivary glands and functional deficit similar to Sjögren's syndrome. In humans, Sjögren's syndrome could be associated with other connective tissue disorders, such as rheumatoid arthritis. In the present study the genetic control of sialadenitis in mice was compared to that of arthritis. We have previously reported a NOD locus, identified in an F2 cross with the H2(q) congenic NOD (NOD.Q) and C57BL/10.Q (B10.Q) strains, that promoted susceptibility to collagen-induced arthritis. The sialadenitis in NOD.Q showed a similar histological phenotype as in NOD, whereas no submandibular gland infiltration was found in B10.Q. The development of sialadenitis was independent of immunization with type II collagen and established arthritis. To identify the genetic control of sialadenitis, a gene segregation experiment was performed on an (NOD.QxB10.Q)F2 cross and genetic mapping of 353 F2 mice revealed one significant locus associated with sialadenitis on chromosome 4, LOD score 4.7. The NOD.Q allele-mediated susceptibility under a recessive inheritance pattern. The genetic control of sialadenitis seemed to be unique in comparison to diabetes and arthritis, as no loci associated with these diseases have been identified at the same location.

Genetic and tissue-specific variation in the expression of a closely linked murine multigene family on chromosome 15 that encodes salivary and lacrimal proteins

The murine submandibular gland (SMG) produces a novel class of highly acidic salivary proteins encoded by one or more highly abundant mRNA transcripts. In inbred mice, these transcripts are encoded by members of a multigene family comprising approximately 8-12 homologues. Most, and probably all, of these homologues are clustered at a new locus near belted (bt) on chromosome 15, which we designate Spt (salivary protein). Although physically closely linked, Spt genes differ in their patterns of expression both in strains of mice and in their tissues. One gene, Spt-1, is expressed at high levels in the SMG of all inbred strains examined. This gene is also expressed at significant levels in the lacrimal gland. A second gene, Spt-2, appears to be present as a single copy in some strains and as two copies in others. This gene is expressed at high levels only in the SMG of those strains carrying two copies, and Spt-2 mRNA is not detectable in the SMG of strains carrying only one copy. In contrast to Spt-1, the Spt-2 gene is not expressed at detectable levels in the lacrimal gland.