GATA2 is expressed in the pituitary during development and in adult gonadotropes and thyrotropes. It is proposed to be important for gonadotrope and thyrotrope cell fate choice and for TSH production. To test this idea, we produced a pituitary-specific knockout of Gata2, designed so that the DNA-binding zinc-finger region is deleted in the presence of a pituitary-specific recombinase transgene. These mice have reduced secretion of gonadotropins basally and in response to castration challenge, although the mice are fertile. GATA2 deficiency also compromises thyrotrope function. Mutants have fewer thyrotrope cells at birth, male Gata2-deficient mice exhibit growth delay from 3-9 wk of age, and adult mutants produce less TSH in response to severe hypothyroidism after radiothyroidectomy. Therefore, Gata2 appears to be dispensable for gonadotrope and thyrotrope cell fate and maintenance, but important for optimal gonadotrope and thyrotrope function. Gata2-deficient mice exhibit elevated levels of Gata3 transcripts in the pituitary gland, suggesting that GATA3 can compensate for GATA2.

The molecular determinants governing cell-specific expression of the thyrotropin (TSH) ␤-subunit gene in pituitary thyrotropes are not well understood. The P1 region of the mouse TSH␤ promoter (؊133 to ؊88) region interacts with Pit-1 and an additional 50-kDa factor at an adjacent site that resembles a consensus GATA binding site. Northern and Western blot assays demonstrated the presence of GATA-2 transcripts and protein in TtT-97 thyrotropic tumors. In electrophoretic mobility shift assays, a comigrating complex was observed with both TtT-97 nuclear extracts and GATA-2 expressed in COS cells. The complex demonstrated binding specificity to the P1 region DNA probe and could be disrupted by a GATA-2 antibody. When both Pit-1 and GATA-2 were combined, a slower migrating complex, indicative of a ternary protein-DNA interaction was observed. Cotransfection of both Pit-1 and GATA-2 into CV-1 cells synergistically stimulated mouse TSH␤ promoter activity 8.5-fold, while each factor alone had a minimal effect. Mutations that abrogated this functional stimulatory effect mapped to the P1 region. Finally, we show that GATA-2 directly interacts with Pit-1 in solution. In summary, these data demonstrate functional synergy and physical interaction between homeobox and zinc finger factors and provide insights into the transcriptional mechanisms of thyrotrope-specific gene expression.Cell-specific expression of eukaryotic genes involves the functional interaction of sets of transcription factors that interact with essential cis-acting promoter regions to initiate RNA transcription. The repertoires of transcription factors that are involved in the expression of genes in highly differentiated cells often consist of those ubiquitously expressed in many cell types in cooperation with others whose expression are cell type-restricted (1, 2). Expression of the thyrotropin (TSH) 1

Single-copy expression of an amyotrophic lateral sclerosis-linked TDP-43 mutation (M337V) in BAC transgenic mice leads to altered stress granule dynamics and progressive motor dysfunction. Ynbdi (2018),

The hsp90 chaperoning pathway is a multiprotein system that is required for the production or activation of many cell regulatory proteins, including the progesterone receptor (PR). We report here the identity of GCUNC-45 as a novel modulator of PR chaperoning by hsp90. GCUNC-45, previously implicated in the activities of myosins, can interact in vivo and in vitro with both PR-A and PR-B and with hsp90. Overexpression and knockdown experiments show GCUNC-45 to be a positive factor in promoting PR function in the cell. GCUNC-45 binds to the ATP-binding domain of hsp90 to prevent the activation of its ATPase activity by the cochaperone Aha1. This effect limits PR chaperoning by hsp90, but this can be reversed by FKBP52, a cochaperone that is thought to act later in the pathway. These findings reveal a new cochaperone binding site near the N terminus of hsp90, add insight on the role of FKBP52, and identify GCUNC-45 as a novel regulator of the PR signaling pathway.The activities of the progesterone receptor (PR) are intimately linked to its associations with other proteins that are essential for normal progesterone action. Unliganded PR is associated with a multifunctional complex of proteins which includes the heat shock proteins hsp70 and hsp90 plus several cochaperone proteins. This heterocomplex is responsible for correct assembly and folding of the PR as well as preventing its degradation (36). Recent studies indicate additional roles for molecular chaperones in receptor trafficking and in the maintenance of receptor function in the nucleus (11,12). Hormone binding promotes conformational changes in the PR and its release from the chaperone complex. The resulting PR dimer is then able to associate with specific coactivators and general transcription factors as well as progestin response elements in the promoters of target genes (13,19,27,44,50).Cell-free systems using the purified proteins have been of crucial importance in dissecting the ordered pathway that leads to the hormone-responsive state of the receptor (36,39,52). This hsp90-dependent chaperoning pathway is initiated by hsp40 and hsp70 binding to PR, followed by the binding of Hop-hsp90 to hsp70 (16). This intermediate complex is then modified by loss of hsp70 and Hop and recruitment of p23, resulting in a receptor able to bind hormone. In the cell, this last step also incorporates the cochaperone FKBP51, FKBP52, or Cyp40, but this step has eluded dissection in vitro.Although the overall mechanism might be as described above, details and dynamics of this process are still unclear. Furthermore, several additional proteins have been discovered recently that interact with hsp90 or hsp70, such as Chip, Bag1, TPR2, and Aha1 (23,31,36,39,52). These are all likely to have important roles in some aspect of hsp70/hsp90 chaperoning to provide a more intricate and versatile process than that described in the current model. There are also a number of proteins that interact with the PR as transcriptional coregulators or to relate PR functions with other cell signa...