A single copy of large tumor suppressor 1 or large tumor suppressor 2 is sufficient for normal hematopoiesis.

ABSTRACT

BACKGROUND: Hematopoietic stem cells (HSCs) have the ability to differentiate into all subsets of blood cells and self-renew. Large tumor suppressor 1 (LATS1) and large tumor suppressor 2 (LATS2) kinases are essential for cell cycle regulation, organism fitness, genome integrity, and cancer prevention. Here, we investigated whether Lats1 and Lats2 are critical for the maintenance of the self-renewal and quiescence capacities of HSCs in mice. METHODS: Quantitative reverse transcription-polymerase chain reaction was used to determine the expression levels of Lats1 and Lats2 in subsets of progenitor cells and mature bone marrow cells. A clustered regularly interspaced short palindromic repeats system was used to generate Lats1 or Lats2 knockout mice. Complete blood cell counts were used to compare the absolute number of white blood cells, lymphocytes, monocytes, neutrophils, and platelets between Lats1 or Lats2 heterozygotes and littermates. Flow cytometry was used to assess the size of hematopoietic progenitor cells (HPCs) and HSC pools in Lats1 or Lats2 heterozygotes and littermates. The comparison between the two groups was analyzed using Student's t test. RESULTS: Lats1 and Lats2 were widely expressed in hematopoietic cells with higher expression levels in primitive hematopoietic cells than in mature cells. Lats1 or Lats2 knockout mice were generated, with the homozygotes showing embryonic lethality. The size of the HPC and HSC pools in Lats1 (HPC wild-type [WT] vs. heterozygote, 220,426.77 ±â€Š54,384.796 vs. 221,149.4 ±â€Š42,688.29, P = 0.988; HSC WT vs. heterozygote, 2498.932 ±â€Š347.856 vs. 3249.763 ±â€Š370.412, P = 0.105) or Lats2 (HPC WT vs. heterozygote, 425,540.52 ±â€Š99,721.86 vs. 467,127.8 ±â€Š89,574.48, P = 0.527; HSC WT vs. heterozygote, 4760.545 ±â€Š1518.01 vs. 5327.437 ±â€Š873.297, P = 0.502) heterozygotes were not impaired. Moreover, the depletion of Lats1 or Lats2 did not affect the overall survival of the heterozygotes (Lats1 P = 0.654; Lats2 P = 0.152). CONCLUSION: These results indicate that a single allele of Lats1 or Lats2 may be sufficient for normal hematopoiesis.