Structural Characterization of the Rat Cysteine-Rich Intestinal Protein Gene and Overexpression of This LIM-Only Protein in Transgenic Mice

Abstract

Cysteine-rich intestinal protein (CRIP) has a double zinc-finger motif called the LIM domain. The most elementary member of the Group 2 LIM-only protein family, CRIP was initially identified as a developmentally regulated intestinal gene. Subsequently, it was found to be highly expressed in immune cells. The structural portion of the rat CRIP gene is comprised of five exons extending over i.8 kb, with the two zinc-finger motifs of the LIM domain being divided among the first three exons. In addition to transcriptional regulatory elements previously identified in the promoter, consensus sequences for AP-1, AP2, Sp-1, and a glucocorticoid response element are located within the first intron. We have developed a line of transgenic mice that overexpress the rat CRIP gene with an expression profile that mirrors that of the endogenous gene. Driven by the homologous rat CRIP promoter, expression increased threefold to sevenfold in intestine, thymus, spleen, and lung over endogenous levels. The transgenic mice had only about 50% of the white blood cell count found in nontransgenic animals. Differential leukocyte counts showed transgenic animals had proportionately fewer lymphocytes and more monocytes, eosinophils, neutrophils. Flow cytometry data suggested that mice overexpressing CRIP have more CD4+/CD8+ thymic lymphocytes. These data suggest that CRIP plays a significant role in differentiation or maturation of cells with rapid turnover such as those found in the intestine and immune system.

Trefoil Factor 2 (Tff2) Deficiency in Murine Digestive Tract Influences the Immune System

“…CRIP plays a significant role in the regulation of cytokine balance and the immune response. Transgenic animals over-expressing CRIP (~3-7 fold) have changed numbers of different white cell types [61] and altered cytokine patterns and immune responses [62]. Dipeptidyl peptidase I (DPPI or Cathepsin C), important for MHC class II antigen presentation [63] regulated in intestine of TFF2-/-mice.…”

Trefoil factors

“…CRIP has a signifi cant role in the regulation of cytokine balance and the immune response. A 3-7-fold overexpression of CRIP achieved in a transgenic mice model caused a change in the population of leukocytes [41] and altered the pattern of cytokine expression and consequently the immune response [42]. Transgenic CRIP overexpressing mice had only 50% of the white blood cell count found in non-transgenic animals.…”

Regulation of Cysteine‐Rich Intestinal Protein, a Zinc Finger Protein, by Mediators of the Immune Response

“…The structural portion of the rat CRIP gene, which comprises 5 exons extending over 1.8 kb as well as 2.6 kb of the upstream regulatory region, was the construct used to develop the Tg mice [16]. Driven by the homologous rat CRIP promoter, expression increased between three-and seven-fold in intestine, thymus, spleen, and lung of the CRIP Tg mice compared with levels in appropriate controls.…”