FIG. 6.

CycT1^−/− mice do not express AIRE-responsive genes in the thymus and display lymphocytic infiltration of lacrimal and salivary glands. (A) Absent expression of CycT1 in the thymus (see Fig. S3 in the supplemental material) parallels the lack of Spt1 and Ins2 transcripts in CycT1^−/− mice. We assessed levels of CycT1, HEXIM1, Cdk9, and GAPDH in the thymuses from WT or CycT1^−/− mice by Western blotting (top). Next, primary mTECs were isolated from the thymuses of WT or CycT1^−/− mice, followed by isolation of total RNA and analyses by RT-qPCR with primers specific for AIRE, actin, Spt1, and Ins2 transcripts (bottom, l to 4). WT and CycT1^−/− denote parental CycT1^+/+ and genetically inactivated CycT1^−/− mice, respectively. Amounts of RNA are expressed relative to those in WT mTECs, with standard errors from three independent measurements. (B) Lack of CycT1 in the mouse results in lymphocytic infiltration of lacrimal and salivary glands. Hematoxylin and eosin staining of formalin-fixed sections of lacrimal and salivary glands from 5- to 7-month-old WT and CycT1^−/− mice is presented. Arrows point to lymphocytic infiltrates in these organs. Photographs were obtained at ×40 and ×100 (insets) magnifications. Below histological sections are presented relative infiltrations of salivary and lacrimal glands of up to 10 CycT1^+/+ and CycT1^+/− (WT) and 21 CycT1^−/− mice. Scoring was performed blindly, as described previously (18).