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Gene Review

Lct  -  lactase

Mus musculus

Synonyms: Gm100, LAC, LOC226413, LPH, Lphl
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Disease relevance of Lct

  • In an examination of the molecular basis of oral transmission of bunyaviruses by mosquitoes., La Crosse (LAC), snowshoe hare (SSH), and LAC-SSH reassortant viruses were compared in their ability to be transmitted to laboratory mice by the natural mosquito vector of LAC virus, Aedes triseriatus [1].
  • Mouse tumor cell beta-lipotropin (beta LPH) and gamma-lipotropin (gamma LPH) were purified from mouse pituitary tumor cell culture medium by ion exchange chromatography and gel filtration [2].
  • La Crosse (LAC) virus is an important cause of pediatric arboviral encephalitis in the United States. LAC virus is biologically transmitted by the mosquito Aedes triseriatus, and, like other arthropod-borne viruses, it establishes a persistent, nonpathogenic infection in its vector following oral infection [3].
  • Diarrheal illness and viral shedding were recorded, and small intestinal tissue was evaluated for rotavirus (NSP4 and structural proteins)- and enterocyte-specific (lactase, SGLT1, and L-FABP) mRNA and protein expression [4].
  • The mortality rate and histopathological features of Nocardia asteroides and Nocardia brasiliensis infections in congenitally athymic (nude) mice of ICR and C3H/eB origins were quite different from what we found for Swiss white mice and other inbred mouse strains (namely, C57/BL/6J, New Zealand Black, BALB/c, CBA/LAC, and C3H/eB) [5].

Psychiatry related information on Lct

  • The means by which diazepam alters the social behavior of male LAC mice was investigated by analyzing 6-min dyadic social encounters between untreated, individually housed resident males and experimentally manipulated, group-housed intruders [6].

High impact information on Lct

  • The aim of this study was to characterize the capacity of regulatory elements within the rat LPH gene to direct appropriate cell lineage and topographical patterns of expression in vivo in transgenic mice [7].
  • METHODS: Transgenic mouse lines were established using a construction containing bases -2038 to +15 of the rat LPH gene fused to a human growth hormone reporter gene [7].
  • Transgene expression along horizontal and developmental gradients was different from that of the native mouse LPH gene [7].
  • Hence, these data validate the use of transgenic animals expressing lactase in the mammary gland to produce low-lactose milk in vivo, and they demonstrate that the secretion of an intestinal digestive enzyme into milk can selectively modify its composition [8].
  • Transgenic females expressed lactase protein and activity during lactation at the apical side of mammary alveolar cells [8].

Chemical compound and disease context of Lct


Biological context of Lct

  • The sequence of 1/2 cystine and tryptophan residues in the mouse tumor 16K fragment can be aligned with one region of the amino acid sequence predicted from the cDNA for a bovine precursor to ACTH/beta LPH (Nakanishi, S., Inoue, A., Kita, T., Nakamura, M., Chang, A.C.Y., Cohen, S.N., and Numa, S. (1979) Nature 278, 423--427) [10].
  • LAC virus genome was detected almost uniformly in midguts at days 3 to 28 postinfection (p.i.) and, as the time p.i. progressed, in more of the samples than either mRNA or viral cRNA (vcRNA) [3].
  • To analyze mechanisms of virulence in the California serogroup bunyaviruses, the virulent La Crosse/original (LAC/original) strain was compared with the avirulent Tahyna/181-57 strain [11].
  • LAC virus RNA genotype diversity was greatest in virus that infected and replicated in the midgut, and declined as virus disseminated from the midgut and infected ovaries and salivary glands [12].
  • To define the importance and underlying mechanism of HNF-1alpha for the regulation of intestinal gene expression in vivo, we analyzed the expression of the intestinal differentiation markers and putative HNF-1alpha targets lactase-phlorizin hydrolase (LPH) and sucrase-isomaltase (SI) in hnf1alpha null mice [13].

Anatomical context of Lct


Associations of Lct with chemical compounds

  • Lactase synthesis in the mammary gland caused a significant decrease in milk lactose (50-85%) without obvious changes in fat and protein concentrations [8].
  • The glycoprotein accounting for most of the nonadrenocorticotropic hormone (ACTH), non-beta-lipotropin (beta LPH) region of mouse tumor cell pro-ACTH/endorphin was purified from tumor cell culture medium and shown to contain 1/2 cystine residues [10].
  • Rat pituitary beta LPH and gamma LPH were shown to be similar to the corresponding mouse tumor cell molecules in size and lack of methionine in their beta-melanotropin-like segment [2].
  • RESULTS: Similar to what occurs during natural development, spermine treatment of neonatal mice increased intestinal length, decreased lactase activity, and increased sucrase activity [17].
  • The pharmacokinetics of pentamethylmelamine (PMM) have been investigated in mouse (Balb C-, CBA/LAC, nude), rat (Wistar), and man [18].

Other interactions of Lct


Analytical, diagnostic and therapeutic context of Lct

  • The mouse tumor cell beta LPH was identified by immunoprecipitation with several antisera to beta-endorphin, generation of opioid bioactivity upon brief treatment with trypsin, and its identity with the molecule previously shown to serve as an intermediate in the biosynthesis of beta-endorphin [2].
  • A species-specific radioimmunoassay for mouse tumor cell gamma LPH was developed [2].
  • A reverse transcription-PCR (RT-PCR) technique was used to detect La Crosse (LAC) virus RNA in the central nervous system (CNS) tissues of two patients who died of LAC encephalitis in 1960 and 1978 [16].
  • Neutralization tests showed the isolates to be different from snowshoe hare, trivittatus, and Jamestown Canyon prototype virus strains but indistinguishable from the LAC prototype [20].
  • LAC antigen was visualized by fluorescent antibody technique in multiple organs of 5 (2.5% of 198 females dissected after contact in mating cages with males, with a transovarial infection rate of 31% [21].


  1. Molecular basis of bunyavirus transmission by mosquitoes: role of the middle-sized RNA segment. Beaty, B.J., Holterman, M., Tabachnick, W., Shope, R.E., Rozhon, E.J., Bishop, D.H. Science (1981) [Pubmed]
  2. Characterization of mouse tumor cell beta-lipotropin. Eipper, B.A., Mains, R.E. J. Biol. Chem. (1979) [Pubmed]
  3. Analysis of La Crosse virus S-segment RNA and its positive-sense transcripts in persistently infected mosquito tissues. Chandler, L.J., Wasieloski, L.P., Blair, C.D., Beaty, B.J. J. Virol. (1996) [Pubmed]
  4. Changes in small intestinal homeostasis, morphology, and gene expression during rotavirus infection of infant mice. Boshuizen, J.A., Reimerink, J.H., Korteland-van Male, A.M., van Ham, V.J., Koopmans, M.P., Büller, H.A., Dekker, J., Einerhand, A.W. J. Virol. (2003) [Pubmed]
  5. Nocardia infections in congenitally athymic (nude) mice and in other inbred mouse strains. Folb, P.I., Timme, A., Horowitz, A. Infect. Immun. (1977) [Pubmed]
  6. A possible olfactory component in the effects of diazepam on social behavior of mice. Dixon, A.K. Psychopharmacology (Berl.) (1982) [Pubmed]
  7. Rat lactase-phlorizin hydrolase/human growth hormone transgene is expressed on small intestinal villi in transgenic mice. Krasinski, S.D., Upchurch, B.H., Irons, S.J., June, R.M., Mishra, K., Grand, R.J., Verhave, M. Gastroenterology (1997) [Pubmed]
  8. Production of low-lactose milk by ectopic expression of intestinal lactase in the mouse mammary gland. Jost, B., Vilotte, J.L., Duluc, I., Rodeau, J.L., Freund, J.N. Nat. Biotechnol. (1999) [Pubmed]
  9. Inhibition of experimental lung metastases of Lewis lung carcinoma cells by chemically modified heparin with reduced anticoagulant activity. Yoshitomi, Y., Nakanishi, H., Kusano, Y., Munesue, S., Oguri, K., Tatematsu, M., Yamashina, I., Okayama, M. Cancer Lett. (2004) [Pubmed]
  10. Partial characterization of a glycoprotein comprising the NH2-terminal region of mouse tumor cell pro-adrenocorticotropic hormone/endorphin. Keutmann, H.T., Eipper, B.A., Mains, R.E. J. Biol. Chem. (1979) [Pubmed]
  11. Mechanisms of bunyavirus virulence. Comparative pathogenesis of a virulent strain of La Crosse and an avirulent strain of Tahyna virus. Janssen, R., Gonzalez-Scarano, F., Nathanson, N. Lab. Invest. (1984) [Pubmed]
  12. The effect of mosquito passage on the La Crosse virus genotype. Borucki, M.K., Kempf, B.J., Blair, C.D., Beaty, B.J. J. Gen. Virol. (2001) [Pubmed]
  13. Hepatocyte nuclear factor-1{alpha} is required for expression but dispensable for histone acetylation of the lactase-phlorizin hydrolase gene in vivo. Bosse, T., van Wering, H.M., Gielen, M., Dowling, L.N., Fialkovich, J.J., Piaseckyj, C.M., Gonzalez, F.J., Akiyama, T.E., Montgomery, R.K., Grand, R.J., Krasinski, S.D. Am. J. Physiol. Gastrointest. Liver Physiol. (2006) [Pubmed]
  14. Furin, PC1/3, and/or PC6A process rabbit, but not human, pro-lactase-phlorizin hydrolase to the 180-kDa intermediate. Keller, P., Zecca, L., Boukamel, R., Zwicker, E., Gloor, S., Semenza, G. J. Biol. Chem. (1995) [Pubmed]
  15. Experimental arthropathy induced in rhesus monkeys and DBA/1 mice by a novel method: intraperitoneal implantation of type II collagen adsorbed onto nitrocellulose filters. Healy, C.T., Martin, L.N., Roberts, E.D., Rubin, A.S. Lab. Invest. (1989) [Pubmed]
  16. Characterization of La Crosse virus RNA in autopsied central nervous system tissues. Chandler, L.J., Borucki, M.K., Dobie, D.K., Wasieloski, L.P., Thompson, W.H., Gundersen, C.B., Case, K., Beaty, B.J. J. Clin. Microbiol. (1998) [Pubmed]
  17. Spermine induces maturation of the immature intestinal immune system in neonatal mice. ter Steege, J.C., Buurman, W.A., Forget, P.P. J. Pediatr. Gastroenterol. Nutr. (1997) [Pubmed]
  18. The comparative pharmacokinetics of pentamethylmelamine in man, rat, and mouse. Rutty, C.J., Newell, D.R., Muindi, J.R., Harrap, K.R. Cancer Chemother. Pharmacol. (1982) [Pubmed]
  19. Physiological roles of gammadelta T-cell receptor intraepithelial lymphocytes in cytoproliferation and differentiation of mouse intestinal epithelial cells. Matsumoto, S., Nanno, M., Watanabe, N., Miyashita, M., Amasaki, H., Suzuki, K., Umesaki, Y. Immunology (1999) [Pubmed]
  20. Isolation of La Crosse virus (California encephalitis group) from the chipmunk (Tamias striatus), an amplifier host. Gauld, L.W., Yuill, T.M., Hanson, R.P., Sinha, S.K. Am. J. Trop. Med. Hyg. (1975) [Pubmed]
  21. Venereal transmission of La Crosse virus from male to female Aedes triseriatus. Thompson, W.H., Beaty, B.J. Am. J. Trop. Med. Hyg. (1978) [Pubmed]
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