Although the main focus of immuno-oncology has been manipulating the adaptive immune system, harnessing both the innate and adaptive arms of the immune system might produce superior tumour reduction and elimination. Tumour-associated macrophages often have net pro-tumour effects, but their embedded location and their untapped potential provide impetus to discover strategies to turn them against tumours. Strategies that deplete (anti-CSF-1 antibodies and CSF-1R inhibition) or stimulate (agonistic anti-CD40 or inhibitory anti-CD47 antibodies) tumour-associated macrophages have had some success. We hypothesized that pharmacologic modulation of macrophage phenotype could produce an anti-tumour effect. We previously reported that a first-in-class selective class IIa histone deacetylase (HDAC) inhibitor, TMP195, influenced human monocyte responses to the colony-stimulating factors CSF-1 and CSF-2 in vitro. Here, we utilize a macrophage-dependent autochthonous mouse model of breast cancer to demonstrate that in vivo TMP195 treatment alters the tumour microenvironment and reduces tumour burden and pulmonary metastases by modulating macrophage phenotypes. TMP195 induces the recruitment and differentiation of highly phagocytic and stimulatory macrophages within tumours. Furthermore, combining TMP195 with chemotherapy regimens or T-cell checkpoint blockade in this model significantly enhances the durability of tumour reduction. These data introduce class IIa HDAC inhibition as a means to harness the anti-tumour potential of macrophages to enhance cancer therapy.

In contrast to studies on class I histone deacetylase (HDAC) inhibitors, the elucidation of the molecular mechanisms and therapeutic potential of class IIa HDACs (HDAC4, HDAC5, HDAC7 and HDAC9) is impaired by the lack of potent and selective chemical probes. Here we report the discovery of inhibitors that fill this void with an unprecedented metal-binding group, trifluoromethyloxadiazole (TFMO), which circumvents the selectivity and pharmacologic liabilities of hydroxamates. We confirm direct metal binding of the TFMO through crystallographic approaches and use chemoproteomics to demonstrate the superior selectivity of the TFMO series relative to a hydroxamate-substituted analog. We further apply these tool compounds to reveal gene regulation dependent on the catalytic active site of class IIa HDACs. The discovery of these inhibitors challenges the design process for targeting metalloenzymes through a chelating metal-binding group and suggests therapeutic potential for class IIa HDAC enzyme blockers distinct in mechanism and application compared to current HDAC inhibitors.

An unusual cAMP signaling system mediates many of the events that prepare spermatozoa to meet the egg. Its components include the atypical, bicarbonate-stimulated, sperm adenylyl cyclase and a cAMP-dependent protein kinase (PKA) with the unique catalytic subunit termed C␣ 2 or Cs. We generated mice that lack C␣2 to determine its importance in the events downstream of cAMP production. Male C␣ 2 null mice produce normal numbers of sperm that swim spontaneously in vitro. Thus, C␣ 2 has no required role in formation of a functional flagellum or the initiation of motility. In contrast, we find that C␣ 2 is required for bicarbonate to speed the flagellar beat and facilitate Ca 2؉ entry channels. In addition, C␣2 is needed for the protein tyrosine phosphorylation that occurs late in the sequence of sperm maturation and for a negative feedback control of cAMP production, revealed here. Consistent with these specific defects in several important sperm functions, C␣ 2 null males are infertile despite normal mating behavior. These results define several crucial roles of PKA in sperm cell biology, bringing together both known and unique PKA-mediated events that are necessary for male fertility. T he terminally differentiated, transcriptionally dormant, and translationally inactive posttesticular spermatozoan has a limited ability to respond to environmental cues encountered as it progresses through the male and female reproductive tracts. During this passage, the bicarbonate anion present in the reproductive fluids (1, 2) has an unexpectedly prominent role in promoting several of the events (3-5), collectively called capacitation, which transform sperm to readiness for fertilization.Much evidence indicates that bicarbonate directly increases production of cAMP by atypical sperm adenylyl cyclase (sAC) (6, 7), and recent work finds that sAC is required for male fertility and normal sperm motility (8). Although cAMP might open ion channels or activate guanine nucleotide exchange factors, most evidence places cAMP-dependent protein kinase (PKA) as the major downstream effector of cAMP signals in sperm. However, only a small number of sperm proteins have been identified as phospho-substrates of PKA (9, 10). We now apply phenotypic analysis of loss-of-function mutants to examine downstream effects of the PKA subunit C␣ 2 . Materials and MethodsTargeted Disruption of C␣2. C␣ 2 null mice were generated from the targeted disruption of exon 1b of the C␣ gene by homologous recombination in embryonic stem (ES) cells. The targeting vector was constructed from a 13.2-kb genomic fragment containing exons 1-3 of C␣. A loxP-flanked neomycin phosphotransferase (NEO) cassette and a mutation of the translational initiation codon were inserted into exon 1b. The linearized targeting vector was electroporated into ES cells derived from 129SV͞J mice as described (11). Germ-line chimeras were bred to C57BL͞6 mice. Pups carrying the NEO were crossed to heterozygous ROSA26-Cre recombinase transgenic mice (from P. Sorriano, Fred Hutchinson Cancer Rese...

Rapid eye movement (REM) sleep is an important component of the natural sleep/wake cycle, yet the mechanisms that regulate REM sleep remain incompletely understood. Cholinergic neurons in the mesopontine tegmentum have been implicated in REM sleep regulation, but lesions of this area have had varying effects on REM sleep. Therefore, this study aimed to clarify the role of cholinergic neurons in the pedunculopontine tegmentum (PPT) and laterodorsal tegmentum (LDT) in REM sleep generation. Selective optogenetic activation of cholinergic neurons in the PPT or LDT during non-REM (NREM) sleep increased the number of REM sleep episodes and did not change REM sleep episode duration. Activation of cholinergic neurons in the PPT or LDT during NREM sleep was sufficient to induce REM sleep.rapid eye movement sleep | acetylcholine | optogenetics | mesopontine tegmentum | mouse R apid eye movement (REM) sleep is tightly regulated, yet the mechanisms that control REM sleep remain incompletely understood. Early pharmacological and unit recording studies suggested that ACh was important for REM sleep regulation (1, 2). For example, injection of cholinergic drugs into the dorsal mesopontine tegmentum reliably induced a state very similar to natural REM sleep in cats (3-6). Unit recordings from the cholinergic areas of the mesopontine tegmentum revealed cells that were active during wakefulness and REM sleep, as well as neurons active only during REM sleep (7-13). Electrical stimulation of the laterodorsal tegmentum (LDT) in cats increased the percentage of time spent in REM sleep (14), and activation of the pedunculopontine tegmentum (PPT) in rats induced wakefulness and REM sleep (15). If cholinergic PPT and LDT neurons are necessary for REM sleep to occur, as the early studies suggest, then lesioning the PPT or LDT should decrease REM sleep. In cats, lesions of the PPT and LDT do disrupt REM sleep (16, 17), but lesions in rodents have had little effect on REM sleep or increased REM sleep (18)(19)(20)(21)(22). Additionally, c-fos studies have found very few cholinergic cells activated under high-REM sleep conditions. When c-fos-positive cholinergic neurons in the PPT and LDT are found to correlate with the percentage of REM sleep, they still account for only a few of the total cholinergic cells in the area (23). Juxtacellular recordings of identified cholinergic neurons in the LDT found these cells had wake and REM active firing profiles, with the majority firing the highest during REM sleep (13). These discrepancies have led to alternative theories of REM sleep regulation, where cholinergic neurons do not play a key role (18, 19, 23, 24 and reviewed in 25, 26).The PPT and LDT are made up of heterogeneous populations of cells, including distinct populations of cholinergic, GABAergic, and glutamatergic neurons (27-29). Many GABAergic neurons are active during REM sleep, as indicated by c-fos (23), and both GABAergic and glutamatergic neurons have been found with maximal firing rates during REM sleep in the LDT and medial PPT (13...