targeted-toxins

Q: Do targeted toxin-treated cells die by apoptosis?

A: There are, allegedly, two ways for cells to die: by apoptosis or necrosis. According to Fiorenzo Stirpe (the discoverer of saporin), saporin-intoxicated cells die both ways, some by one, others by the other.

There is good literature that states that cells die by apoptosis. Saporin and apoptosis gives 25 hits in PubMed. For instance:

Bergamaschi G, Perfetti V, et al. (1996). Saporin, a ribosome-inactivating protein used to prepare immunotoxins, induces cell death via apoptosis. Brit J Haemat 93:789-794.

However, Seeger et al., did not find evidence of apoptosis in an electron microscopy study with cells dying from 192-IgG-SAP and concluded they die from necrosis. Saporin and necrosis gives 11 hits in PubMed.

Seeger G, Hartig W, et al. (1997). Electron microscopic evidence for microglial phagocytotic activity and cholinergic cell death after administration of the immunotoxin 192IgG-saporin in rat. J Neurosci Res 48:465-476.

So, saporin-treated cells seem to die by both apoptosis and necrosis. The customer is always right.

Radley JJ (2008) Featured Article: Noradrenergic innervation of the dorsal medial prefrontal cortex modulates hypothalamo-pituitary-adrenal responses to acute emotional stress. Targeting Trends 9(3)

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)

Read the featured article in Targeting Trends.

See Also:

• Radley JJ et al. Noradrenergic innervation of the dorsal medial prefrontal cortex modulates hypothalamo-pituitary-adrenal responses to acute emotional stress. J Neurosci 28:5806-5816, 2008.

McKay LC, Feldman JL (2008) Unilateral ablation of preBotzinger Complex disrupts breathing during sleep but not wakefulness. Am J Respir Crit Care Med 178(1):89-95. doi: 10.1164/rccm.200712-1901OC

Summary: Previous data has shown that ablation of preBötzinger complex (preBötC) neurokinin 1 expressing (NK1R) neurons disrupts breathing patterns in both sleep and wakefulness. The initial disruption is during sleep, with the eventual onset of ataxic breathing while the animals are awake. Here rats received a unilateral injection of SP-SAP (Cat. #IT-07, 6.7 ng) into the left preBötC. SP plus unconjugated saporin (Cat. #PR-01) was used as a control. Unilaterally treated rats did not develop disrupted breathing patterns during wakefulness.

Related Products: SP-SAP (Cat. #IT-07), Saporin (Cat. #PR-01)

Bogen O, Joseph EK, Chen X, Levine JD (2008) GDNF hyperalgesia is mediated by PLCgamma, MAPK/ERK, PI3K, CDK5 and Src family kinase signaling and dependent on the IB4-binding protein versican. Eur J Neurosci 28:12-19. doi: 10.1111/j.1460-9568.2008.06308.x

Summary: C-fiber nociceptors have been divided into NGF and GDNF classes. Here the authors examined the function of an isolectin B4-binding subpopulation of these nocicepetors. Rats received 40 ng of IB4-SAP (Cat. #IT-10) into the intrathecal space between the fifth and sixth lumbar vertebrae. The results demonstrate that GDNF sensitizes IB4+ C-fiber nociceptors and causes mechanical hyperalgesia.

Related Products: IB4-SAP (Cat. #IT-10)

De Bartolo P, Leggio MG, Mandolesi L, Foti F, Gelfo F, Ferlazzo F, Petrosini L (2008) Environmental enrichment mitigates the effects of basal forebrain lesions on cognitive flexibility. Neuroscience 154(2):444-453. doi: 10.1016/j.neuroscience.2008.03.069

Summary: The basal forebrain cholinergic system is a crucial participant in various facets of learning and memory. This work examines whether environmental enrichment can reduce the effect of cholinergic lesions on learning and memory tasks. Rats received bilateral injections of 192-IgG-SAP (Cat. #IT-01) into the cholinergic projection to the neocortex. Deficits caused by the lesion were attenuated in rats experiencing an enriched environment.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Zinck ND, Downie JW (2008) IB4 afferent sprouting contributes to bladder dysfunction in spinal rats. Exp Neurol 213:293-302. doi: 10.1016/j.expneurol.2008.06.006

Summary: Spinal cord injury can cause inefficient bladder function, but the direct cause is not well understood. Most work has focused on afferent neurons that contain CGRP and respond to NGF. Here the authors investigate the role of isolectin B4 (IB4)-expressing neurons that are supported by GDNF. Rats received intrathecal injections of either 2.4 µg IB4-SAP (Cat. #IT-10) or 3 µg control saporin (Cat. #PR-01). The data suggest that IB4-afferent sprouting is involved in bladder dysfunction following spinal cord transection.

Related Products: IB4-SAP (Cat. #IT-10), Saporin (Cat. #PR-01)

Takakura AC, Moreira TS, Stornetta RL, West GH, Gwilt JM, Guyenet PG (2008) Selective lesion of retrotrapezoid Phox2b-expressing neurons raises the apneic threshold in rats. J Physiol 586:2975-2991. doi: 10.1113/jphysiol.2008.153163

Summary: It is thought that transcription factor Phox2b-expressing glutamatergic interneurons are involved in the activation of breathing by elevated CO2 in the central nervous system. This activation is otherwise known as the central chemoreflex. Injections of SSP-SAP (Cat. #IT-11) into the retrotrapezoid nucleus eliminated Phox2b+TH- neurons but spared other neuron classes. Several different amounts of the conjugate were used (0.15, 0.3, or 0.6 ng in 1 or 2 injections). Elimination of ≥70% of Phox2b+TH- neurons markedly attenuated the central chemoreflex.

Related Products: SSP-SAP (Cat. #IT-11)

Darmani NA, Wang Y, Abad J, Ray AP, Thrush GR, Ramirez J (2008) Utilization of the least shrew as a rapid and selective screening model for the antiemetic potential and brain penetration of substance P and NK1 receptor antagonists. Brain Res 1214:58-72. doi: 10.1016/j.brainres.2008.03.077

Summary: This work investigated the role of central tachykinin NK1 receptors in delayed phase vomiting caused by chemotherapeutics. Least shrews received 1.2 mg/kg intraperitoneal injections of SSP-SAP (Cat. #IT-11). Saporin (Cat. #PR-01) and blank-SAP (Cat. #IT-21) were used as controls. In response to administration of a NK1 receptor agonist lesioned animals vomited less than the control group, indicating an important role for NK1 receptors in emesis.

Related Products: SSP-SAP (Cat. #IT-11), Saporin (Cat. #PR-01), Blank-SAP (Cat. #IT-21)

Li AJ, Dinh TT, Ritter S (2008) Hyperphagia and obesity produced by arcuate injection of NPY-saporin do not require upregulation of lateral hypothalamic orexigenic peptide genes. Peptides 29(10):1732-1739. doi: 10.1016/j.peptides.2008.05.026

Summary: It has already been shown that lesioning NPY receptor-expressing cells in the arcuate nucleus (Arc) and basomedial hypothalamus produces obesity in rats. The authors examined the contribution of orexigenic peptides, orexins, and melanocortin-concentrating hormone to the lesion effects. Rats received bilateral 24 ng injections of NPY-SAP (Cat. #IT-28) into the dorsal border of the Arc. Blank-SAP (Cat. #IT-21) was used as a control. The data suggest that obesity produced by NPY-SAP lesion is different than dietary obesity or obesity associated with leptin or leptin receptor deficiency.

Related Products: NPY-SAP (Cat. #IT-28), Blank-SAP (Cat. #IT-21)

Li A, Emond L, Nattie E (2008) Brainstem catecholaminergic neurons modulate both respiratory and cardiovascular function. (eds. Poulin MJ, Wilson RJA). In: Integration in Respiratory Control. Advances in Experimental Medicine and Biology 605:371-376. Springer, New York, NY. doi: 10.1007/978-0-387-73693-8_65

Summary: The authors examined the role of brainstem catecholamine (CA) neurons in various aspects of breathing and chemoreception. Rats received 5-µg injections of anti-DBH-SAP (Cat. #IT-03) into the 4th ventricle; mouse IgG-SAP (Cat. #IT-18) was used as a control. This method of lesioning left the CA neurons in the peripheral nervous system intact. Lesioned animals displayed a constant decrease in breathing frequency, reduced response to CO2, and increased variability of breathing during REM sleep. Inhibitory cardiovascular effects were also seen.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)