We have cloned a novel protein kinase from human cerebellum and named it LZK (leucine zipper-bearing kinase). The LZK cDNA encoded a 966-amino acid polypeptide that contains a kinase catalytic domain and double leucine/isoleucine zippers separated by a short spacer region. The amino acid sequence of the kinase catalytic domain was a hybrid between those in serine/ threonine and tyrosine protein kinases, indicating that LZK belongs to the subfamily of the mixed lineage kinase (

The effects of zinc L-carnosine on ethanol-induced damage and the correlation of these effects with endogenous prostaglandin E2 were evaluated in rat gastric mucosa in vivo and in vitro. When given either intragastrically or intraperitoneally, zinc L-carnosine (10 or 30 mg/kg) prevented gross visible damage to gastric mucosa caused by ethanol without affecting the mucosal prostaglandin E2 level. This protective effect of zinc L-carnosine was not inhibited by indomethacin. Histological assessment showed that zinc L-carnosine inhibited deep mucosal necrosis, as did 16,16-dimethyl prostaglandin E2. Zinc L-carnosine (10(-6) or 10(-5) M) inhibited the damage caused by ethanol to gastric cells isolated from rat gastric mucosa in vitro; this effect was not inhibited by indomethacin. The results suggested that zinc L-carnosine protects the gastric mucosa and enhances cellular resistance to ethanol without the mediation of endogenous prostaglandins.

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Abstract. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcriptional factor implicated in regulating adipogenesis, glucose homeostasis, and in mediating the action of the insulin sensitizing anti-diabetic thiazolidinedione (TZD) compounds. [3-(2,4-Dichlorobenzyl)-2-methyl-N-(pentylsulfonyl)-3-H-benzimidazole-5-carboxamide] (FK614) is a structurally novel PPARγ agonist that demonstrates potent anti-diabetic activity in vivo. Herein, we describe that FK614 is a selective PPARγ ligand with specific transactivation properties that are dependent upon the context of coactivators. FK614 dissociates the corepressors NCoR (nuclear receptor corepressor) and SMRT (silencing mediator of retinoid and thyroid hormone receptors) from PPARγ as effectively as rosiglitazone and pioglitazone, but can also differentially induce a ligand specific interaction of PPARγ with coactivators. The amount of CBP (CREBbinding protein) and SRC-1 (steroid receptor coactivator-1) recruited by FK614 was less than that induced by rosiglitazone and pioglitazone, but FK614 caused similar PGC-1α (PPARγ coactivator-1α) recruitment as these compounds. As a consequence of these ligand-specific differences in the strength of ligand-type specific interactions of PPARγ and coactivators, FK614 functions as a partial or full agonist for transcriptional activation depending upon the amount of specific coactivators in cells following overexpression. In conclusion, FK614 is a novel, non-TZD type, and selective PPARγ modulator whose pharmacological properties are distinct from rosiglitazone and pioglitazone.

Loss‐of‐function variants of triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk of developing Alzheimer's disease (AD). The mechanism through which TREM2 contributes to the disease (TREM2 activation vs inactivation) is largely unknown. Here, we analyzed changes in a gene set downstream of TREM2 to determine whether TREM2 signaling is modified by AD progression. We generated an anti‐human TREM2 agonistic antibody and defined TREM2 activation in terms of the downstream expression changes induced by this antibody in microglia developed from human induced pluripotent stem cells (iPSC). Differentially expressed genes (DEGs) following TREM2 activation were compared with the gene set extracted from microglial single nuclear RNA sequencing data of patients with AD, using gene set enrichment analysis. We isolated an anti‐TREM2‐specific agonistic antibody, Hyb87, from anti‐human TREM2 antibodies generated using binding and agonism assays, which helped us identify 300 upregulated and 251 downregulated DEGs. Pathway enrichment analysis suggested that TREM2 activation may be associated with Th2‐related pathways. TREM2 activation was lower in AD microglia than in microglia from healthy subjects or patients with mild cognitive impairment. TREM2 activation also showed a significant negative correlation with disease progression. Pathway enrichment analysis of DEGs controlled by TREM2 activity indicated that TREM2 activation in AD may lead to anti‐apoptotic signaling, immune response, and cytoskeletal changes in the microglia. We showed that TREM2 activation decreases with AD progression, in support of a protective role of TREM2 activation in AD. In addition, the agonistic anti‐TREM2 antibody can be used to identify TREM2 activation state in AD microglia.

Adipogenesis is an important process for the improvement of insulin resistance by peroxisome proliferator-activated receptor (PPAR) ␥ agonists, such as rosiglitazone and pioglitazone. FK614 [3-(2,4-dichlorobenzyl)-2-methyl-N-(pentylsulfonyl)-3-Hbenzimidazole-5-carboxamide] is a structurally novel class of PPAR␥ agonist that improves insulin sensitivity in animal models of type 2 diabetes. Herein, we characterize FK614, a selective PPAR␥ modulator (SPPARM) with differential properties affecting the regulation of fat cell function. FK614 behaves as a partial agonist in inducing the interaction of PPAR␥ with both transcriptional coactivators, cAMP response element-binding protein-binding protein and steroid receptor coactivator-1, but as a full agonist with both PPAR-binding protein and PPARinteracting protein, which are required for PPAR␥-mediated adipogenesis. In the differentiating 3T3-L1 adipocytes, the levels of adipose fatty acid-binding protein (aP2) mRNA expression and triglyceride accumulation induced by FK614 were as efficacious as those of rosiglitazone and pioglitazone. In contrast, the effect of FK614 on aP2 gene expression in mature adipocytes was less than that of the other PPAR␥ agonists. Furthermore, the long-term treatment of mature adipocytes with rosiglitazone and pioglitazone reduced the expression of phosphodiesterase 3B, the down-regulation of which has an important role in the development of insulin resistance; however, FK614 had no such effect in mature adipocytes. Thus, FK614 behaves as an SPPARM with differential effects on the activation of PPAR␥ at each stage of adipocyte differentiation. The stage-dependent selectivity of FK614 may contribute to its enhanced insulin sensitization in differentiating adipocytes and to reduced insulin resistance at the stage of adipocyte hypertrophy.

Progranulin (PGRN) haploinsufficiency associated with loss-of-function mutations in the granulin gene causes frontotemporal dementia (FTD). This suggests that increasing PGRN levels could have promising therapeutic implications for patients carrying GRN mutations. In this study, we explored the therapeutic potential of sortilin1 (SORT1), a clearance receptor of PGRN, by generating and characterizing monoclonal antibodies against SORT1. Anti-SORT1 monoclonal antibodies were generated by immunizing Sort1 knockout mice with SORT1 protein. The antibodies were classified into 7 epitope bins based on their competitive binding to the SORT1 protein and further defined by epitope bin-dependent characteristics, including SORT1-PGRN blocking, SORT1 down-regulation, and binding to human and mouse SORT1. We identified a positive correlation between PGRN up-regulation and SORT1 down-regulation. Furthermore, we also characterized K1-67 antibody via SORT1 down-regulation and binding to mouse SORT1 in vivo and confirmed that K1-67 significantly up-regulated PGRN levels in plasma and brain interstitial fluid of mice. These data indicate that SORT1 down-regulation is a key mechanism in increasing PGRN levels via anti-SORT1 antibodies and suggest that SORT1 is a potential target to correct PGRN reduction, such as that in patients with FTD caused by GRN mutation.

FK614 is a structurally novel class of peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, with the mechanism of its insulin-sensitizing action most likely due to activation of PPARgamma. In this study, properties of FK614 for PPARgamma binding, ability to induce conformational change, and coactivator recruitment were investigated. FK614, rosiglitazone, and pioglitazone competed specific binding of [3H]rosiglitazone to PPARgamma with Ki values of 11 nM, 47 nM, and 1.3 microM, respectively. Limited trypsin digestion of PPARgamma with FK614 or rosiglitazone produced distinct patterns of digested polypeptides, suggesting that FK614 directly binds to PPARgamma but induces specific alterations in receptor conformation. FK614 induced interaction of PPARgamma with nuclear receptor coactivator CBP but of lower magnitude than rosiglitazone and pioglitazone. The estimated Kd values of FK614-, rosiglitazone-, and pioglitazone-PPARgamma complex to CBP peptide were 1.8, 0.64, and 0.72 microM, respectively, indicating FK614-PPARgamma complex exhibits a lower affinity for CBP peptide compared to other agonist-PPARgamma complexes. When tested the effect of FK614 on CBP recruitment induced by 9(S)-hydroxyoctadecadienoic acid, an endogenous ligand, FK614 negatively modulated PPARgamma activation. The unique properties of FK614 may underlie the molecular basis of ligand-dependent transcriptional modulation mediated by PPARgamma.