Markku Pelto-Huikko

Estrogen Receptor β Is Coexpressed with ERα and PR and Associated with Nodal Status, Grade, and Proliferation Rate in Breast Cancer

The role of estrogen (ER) and progesterone receptors (PR) in breast cancer is well established. Identification of the second human estrogen receptor, the estrogen receptor β (ERβ), prompted us to evaluate its role in breast cancer. We studied the expression of ERβ by immunohistochemistry and mRNA in situ hybridization in 92 primary breast cancers and studied its association with ERα, PR, and various other clinicopathological factors. Sixty percent of tumors were defined as ERβ-positive (nuclear staining in >20% of the cancer cells). Normal ductal epithelium and 5 of 7 intraductal cancers were also found to express ERβ. Three-fourths of the ERα- and PR-positive tumors were positive for ERβ, whereas ERα and PR were positive in 87% and 67. of ERβ-positive tumors, respectively. ERβ was associated with negative axillary node status ( P P = 0.0003), low S-phase fraction ( P = 0.0003), and premenopausal status ( P = 0.04). In conclusion, the coexpression of ERβ with ERα and PR as well as its association with the other indicators of low biological aggressiveness of breast cancer suggest that ERβ-positive tumors are likely to respond to hormonal therapy. The independent predictive value of ERβ remains to be established.

Prominent expression of acidic fibroblast growth factor in motor and sensory neurons

Several growth factors originally characterized and named for their action on a variety of cells have more recently been suggested to be importantly involved in the development and maintenance of the nervous system. Acidic fibroblast growth factor (aFGF) is a member of a family of seven structurally related polypeptide growth factors. The cells responsible for expression of aFGF in the nervous system of adult rats have been identified using an affinity-purified antibody to aFGF in immunohistochemical studies and synthetic oligonucleotide probes for in situ hybridization studies. High levels of aFGF expression were observed in motoneurons, primary sensory neurons, and retinal ganglion neurons. Glial cells did not express detectable amounts of aFGF. Confocal and electron microscopic analysis suggested that a large portion of aFGF immunoreactivity was associated with the cytoplasmic face of neuronal membranes, consistent with the hypothesis that aFGF is a sequestered growth factor.

Human Mitochondrial Thioredoxin INVOLVEMENT IN MITOCHONDRIAL MEMBRANE POTENTIAL AND CELL DEATH

Thioredoxins (Trx) are a class of small multifunctional redox-active proteins found in all organisms. Recently, we reported the cloning of a mitochondrial thioredoxin, Trx2, from rat heart. To investigate the biological role of Trx2 we have isolated the human homologue, hTrx2, and generated HEK-293 cells overexpressing Trx2 (HEK-Trx2). Here, we show that HEK-Trx2 cells are more resistant toward etoposide. In addition, HEK-Trx2 are more sensitive toward rotenone, an inhibitor of complex I of the respiratory chain. Finally, overexpression of Trx2 confers an increase in mitochondrial membrane potential, ΔΨm. Treatment with oligomycin could both reverse the effect of rotenone and decrease the membrane potential suggesting that Trx2 interferes with the activity of ATP synthase. Taken together, these results suggest that Trx2 interacts with specific components of the mitochondrial respiratory chain and plays an important role in the regulation of the mitochondrial membrane potential.

VIP like immunoreactive nerves in human respiratory tract

SummaryThe present study provides light and electron microscopical evidence of Vasoactive Intestinal Peptide — (VIP) like immunoreactive nerves in human lower respiratory tract. Peroxidase antiperoxidase (PAP) technique was used to localize VIP-like immunoreactivity light microscopically and ultrastructurally.Under light microscopy, VIP-like immunoreactive nerves were observed in the smooth muscle layer of secondary bronchi to small bronchioli, and in bronchial glands. In addition, positive immunoreactive nervous network to VIP was found around nerve cell bodies in small microganglia. The bronchial epithelium of airway tract did not receive any VIP positive nerve fibers. Ultrastructurally VIP-like positive immunoreaction was localized in large granular vesicles ranging from 90 to 210 nm. Usually VIP-like positive immunoreactive nerve profiles contained several immunoreactive large vesicles (100–210). However, nerve profiles containing only a few positive large vesicles (80–150) were also observed. Under electron microscopy VIP-positive nerve profiles corresponded ultrastructurally to nerve profiles containing large granular vesicles observed in conventional electronmicroscopy.The present study provides new information about the innervation of human lower airway tract and widens the concept of their functional regulation on the anatomical basis reported here.

Metalloprotease-disintegrin (ADAM) genes are widely and differentially expressed in the adult CNS.

ADAM family of metalloprotease-disintegrins, including enzymes that process TNF-alpha and beta-amyloid precursor protein, has been indicated in neuronal development, but the role of these protease/adhesion/signaling proteins in adult nervous system remains poorly understood. Present study provides a systematic examination of ADAM gene expression in rodent CNS, showing the first quantitative characterization of ADAM mRNA distribution therein. At least 17 ADAM mRNAs were expressed. Individual ADAM mRNAs and their isoforms showed strikingly different expression patterns. Expression of mRNAs for ADAM10, the putative alpha-secretase, and ADAM17 (TACE), also indicated in APP processing, was further characterized using in situ hybridization. Expression of ADAM10 mRNA was widespread, while ADAM17 showed a more restricted pattern. Altogether, the wide and differential expression of ADAM mRNAs suggests versatile roles for ADAMs in the adult CNS.

Mechanical loading regulates the expression of tenascin-C in the myotendinous junction and tendon but does not induce de novo synthesis in the skeletal muscle

Tenascin-C is a hexabrachion-shaped matricellular protein with a very restricted expression in normal musculoskeletal tissues, but it is expressed abundantly during regenerative processes of these tissues and embryogenesis. To examine the importance of mechanical stress for the regulation of tenascin-C expression in the muscle-tendon unit, the effects of various states of mechanical loading (inactivity by cast-immobilization and three-varying intensities of subsequent re-activity by treadmill running) on the expression of tenascin-C were studied using immunohistochemistry and mRNA in situ hybridization at the different locations of the muscle-tendon unit of the rat gastrocnemius muscle, the Achilles tendon complex. This muscle-tendon unit was selected as the study site, because the contracting activity of the gastrocnemius-soleus muscle complex, and thus the mechanical loading-induced stimulation, is easy to block by cast immobilization. Tenascin-C was expressed abundantly in the normal myotendinous and myofascial junctions, as well as around the cells and the collagen fibers of the Achilles tendon. Tenascin-C expression was not found in the normal skeletal muscle, although it was found in blood vessels within the muscle tissue. Following the removal of the mechanical loading-induced stimulation on the muscle-tendon unit by cast immobilization for 3 weeks, the immonoreactivity of tenascin-C substantially decreased or was completely absent in the regions expressing tenascin-C normally. Restitution of the mechanical loading by removing the cast and allowing free cage activity for 8 weeks resulted in an increase in tenascin-C expression, but it could not restore the expression of tenascin-C to the normal level (in healthy contralateral leg). In response to the application of a more strenuous mechanical loading stimulus after the removal of the cast (after 8 weeks of low- and high-intensity treadmill running), the expression of tenascin-C was markedly increased and reached the level seen in the healthy contralateral limb. Tenascin-C was abundantly expressed in myotendinous and myofascial junctions and in the Achilles tendon, but even the most strenuous mechanical loading (high-intensity treadmill running) could not induce the expression of tenascin-C in the skeletal muscle. This was in spite of the marked immobilization-induced atrophy of the previously immobilized skeletal muscle, which had been subjected to intensive stress during remobilization. mRNA in situ hybridization analysis confirmed the immunohistochemical results for the expression of tenascin-C in the study groups. In summary, this study shows that mechanical loading regulates the expression of tenascin-C in an apparently dose-dependent fashion at sites of the muscle-tendon unit normally expressing tenascin-C but can not induce de novo synthesis of tenascin-C in the skeletal muscle without accompanying injury to the tissue. Our results suggest that tenascin-C provides elasticity in mesenchymal tissues subjected to heavy tensile loading.

Colocalization of Peptide and Glucocorticoid Receptor Immunoreactivities in Rat Central Amygdaloid Nucleus

The central amygdaloid nucleus (ACe) is part of the amygdaloid complex that participates in adrenocorticotrophin secretion, stress-related reactions and behavioral functions. The ACe contains numerous glucocorticoid receptor (GR)-immunoreactive (IR) neurons, and in addition it has been shown to contain several neuropeptide-IR somata and nerve terminals. In order to study the relationship between the GR- and neuropeptide-IR structures we mapped the distribution of GR-like immunoreactivity (LI) in amygdaloid complex and colocalized the neuropeptide- and GR-LIs in the ACe. In the amygdaloid complex the central, medial and cortical nuclei contained a high number of GR-IR neurons, whereas a moderate number of GR-IR neurons were observed in the basolateral and basomedial nuclei. Only a few GR-IR neurons were seen in the lateral nucleus. In the ACe, the majority of corticotrophin-releasing factor (CRF)-, met-enkephalin (met-ENK)-, neurotensin (NT)- and somatostatin (SOM)-IR neurons contained also GR-IR. About half of the substance P (SP)-IR neurons were seen to contain GR-IR, whereas only some of the few vasoactive intestinal polypeptide and cholecystokinin-IR neurons showed GR-LI. Nerve terminals containing calcitonin gene-related peptide and the above mentioned peptides were seen in close contact with the GR-IR neurons. These results suggest that the glucocorticoids may modulate directly the neurotransmitter synthesis of the CRF-, met-ENK, NT-, SOM- and SP-IR cells in the ACe.

Neuropeptide Y (NPY)-like immunoreactivity in rat sympathetic neurons and small granule-containing cells

The distribution of neuropeptide Y-like immunoreactivity (NPY-LI) was examined in the rat superior cervical and hypogastric ganglia. NPY-LI was localized in the majority of the sympathetic neurons, a few small granule-containing (SGC) cells and nerve terminals. Most of the NPY-immunoreactive sympathetic neurons were also tyrosine hydroxylase (TH)-immunoreactive but in hypogastric ganglia few neurons with NPY-LI were devoid of TH-immunoreactivity. Electron microscopically NPY-LI was found in the Golgi complexes of sympathetic neurons, in large cytoplasmic granules (100-150 nm in diameter) of the SGC cells and in large dense-cored vesicles (80-100 nm in diameter) of the nerve terminals. NPY-LI coexists mainly with noradrenaline in sympathetic neurons, and may have regulatory functions in sympathetic ganglia and in target organs.

Localization of the peroxisome proliferator-activated receptor in the brain

This paper describes the localization of the alpha-type peroxisome proliferator-activated receptor (PPAR alpha) in the rat brain using immunocytochemistry and in situ hybridization. Expression of PPAR alpha mRNA was highest in the granular cells of the cerebellar cortex and in the dentate gyrus, with a somewhat lower expression in areas CA1-CA4 of the hippocampus. PPAR alpha mRNA was also found in some neurones of the cerebral cortex (layers II-IV) and the molecular layer of the cerebellar cortex, and in the olfactory tubercle. Immunocytochemistry revealed nuclear PPAR alpha-immunoreactivity (-IR) in the same areas as seen with the in situ hybridization. Furthermore, PPAR alpha-IR was also localized in oligodendrocytes, whereas the other glial cell types appeared to lack PPAR alpha. These results suggest that peroxisome proliferators and chemicals acting similarly have effects on discrete populations of neurones. The presence of PPAR alpha in oligodendrocytes lends further support to the suggestion that peroxisomes are important in the assembly and degradation of myelin.

Mild hypoxia preconditioning prevents impairment of passive avoidance learning and suppression of brain NGFI-A expression induced by severe hypoxia.

The aim of this work was to study effects of mild preconditioning hypobaric hypoxia (380 Torr for 2 h, repeated 3 or 6 times spaced at 24 h) on brain NGFI-A immunoreactivity and passive avoidance (PA) behavior in rats exposed to severe hypoxia (160 Torr for 3 h). Severe hypobaric hypoxia produced extensive neuronal loss in hippocampal CA1, while the preceding hypoxic preconditioning had clear protective effect on neuronal viability of vulnerable hippocampal cells. Besides, the hypoxic preconditioning prevented impairment of acquisition and retention of PA caused by severe hypoxia. The six-trial hypobaric preconditioning was more effective in protection against PA learning deficits in severe hypoxia exposed rats than the three-trial preconditioning. The preconditioning up-regulated severe hypoxia-suppressed neocortical and hippocampal expression of NGFI-A, suggesting a possible role for NGFI-A in the neuroprotective mechanisms activated by hypoxic preconditioning.