Jianhong Shen

CDK5 Contributes to Neuronal Apoptosis via Promoting MEF2D Phosphorylation in Rat Model of Intracerebral Hemorrhage

Cyclin-dependent kinase-5 (CDK5), a serine/threonine kinase which can be activated by its neuron-specific activator p35, or its truncated form p25, plays an important role in a variety of neuronal events, including neuronal migration, synaptic transmission, and neuronal death. Accumulating evidence has shown that abnormal activation of CDK5 was a critical neuronal pro-death signal in central nervous system (CNS) diseases. However, it remains unclear how CDK5 functions upon neuronal apoptosis following intracerebral hemorrhage (ICH). In the present study, we established ICH models by injecting autologous whole blood into the right basal ganglia of adult rats and assessed their neurological deficits by behavioral tests. CDK5 protein levels and kinase activities were upregulated adjacent to the hematoma following ICH. Immunofluorescent staining showed CDK5 was mainly localized in neurons, rather than in astrocytes or oligodendrocytes. Furthermore, active caspase-3, an apoptotic marker, showed a temporally parallel expression with the protein levels/kinase activities of CDK5 following ICH. Meantime, myocyte enhancer factor 2D (MEF2D), a pro-survival transcription factor which could be phosphorylated inactivation by CDK5, also exhibited high phosphorylation levels following ICH. In vitro, we obtained a consistent upregulation of CDK5 kinase activity in primary cortical neurons after thrombin treatment. Knocking down CDK5 kinase activity suppressed neuronal apoptosis and coupled with reduced MEF2D phosphorylation at ser444 residues. Thus, we speculated that CDK5 might exert an important function in the regulation of neuronal apoptosis following ICH.

Antidepressant-like effects of ginsenoside Rg3 in mice via activation of the hippocampal BDNF signaling cascade

Current antidepressants are clinically effective only after several weeks of administration. Ginsenoside Rg3 is one component of ginsenosides, with a similar chemical structure to ginsenoside Rg1. Here, we investigated the antidepressant effects of Rg3 in mouse models of depression. The antidepressant actions of Rg3 were first examined in the forced swim test (FST) and tail suspension test (TST), and then assessed in the chronic social defeat stress (CSDS) model of depression. The changes in the hippocampal brain-derived neurotrophic factor (BDNF) signaling pathway after CSDS and Rg3 treatment were investigated. A tryptophan hydroxylase inhibitor and a BDNF signaling inhibitor were also used to determine the pharmacological mechanisms of Rg3. It was found that Rg3 produced antidepressant effects in the FST and TST without affecting locomotor activity. Rg3 also prevented the CSDS-induced depressive-like symptoms. Moreover, Rg3 fully restored the CSDS-induced decrease in the hippocampal BDNF signaling pathway, and use of the BDNF signaling inhibitor blocked the antidepressant effects of Rg3. In conclusion, ginsenoside Rg3 has antidepressant effects via promotion of the hippocampal BDNF signaling pathway.

Up-regulation of VCAM1 Relates to Neuronal Apoptosis After Intracerebral Hemorrhage in Adult Rats

AbstractVascular cell adhesion molecule 1 (VCAM1) is a member of the Immunoglobulin superfamily and encodes a cell surface sialoglycoprotein expressed in cytokine-activated endothelium. This type I membrane protein mediates leukocyte-endothelial cell adhesion, facilitates the downstream signaling, and may play a role in the development of artherosclerosis and rheumatoid arthritis. Accumulating evidence has demonstrated that VCAM1 exerts an anti-apoptotic effect in several tumor tissues such as ovarian cancer and breast cancer. Intracerebral hemorrhage (ICH) is the second most common subtype of stroke with high morbidity and mortality, which imposes a big burden on individuals and the whole society. These together prompted us to question whether VCAM1 has some association with neuron apoptosis during the pathological process of ICH. An ICH rat model was established and assessed by behavioral tests in order to explore the role of VCAM1 after ICH. Up-regulation of VCAM1 was observed in brain areas surrounding the hematoma following ICH by western blotting and immunohistochemistry. Immunofluorescence manifested VCAM1 was strikingly increased in neurons, but not in astrocytes and microglia. Furthermore, we detected that neuronal apoptosis marker active caspase-3 had co-localizations with VCAM1. At the same time, Bcl-2 was also co-localized with VCAM1. Taken together, our findings suggested that VCAM1 might be involved in the neuronal apoptosis and pathophysiology of ICH.

BTEB2 prevents neuronal apoptosis via promoting bad phosphorylation in rat intracerebral hemorrhage model.

Krüppel-like zinc-finger transcription factor 5 (KLF5), known as BTEB2 or IKLF, has several biological functions that involve cell proliferation, development and apoptosis. Previous studies demonstrated that BTEB2 had anti-apoptotic effect in multiple diseases such as esophageal cancer and non-small cell lung cancers (NSCLCs). However, the distribution and function of BTEB2 in CNS diseases remain unknown. In this study, we show that BTEB2 down-regulates neuronal apoptosis during pathophysiological processes of intracerebral hemorrhage (ICH). A rat ICH model was established by behavioral tests. Western blot and immunohistochemistry revealed a remarkable up-regulation of BTEB2 expression surrounding the hematoma after ICH. Double-labeled immunofluorescence showed BTEB2 was mostly co-localized with neurons, rarely with activated astrocytes and microglia. Furthermore, we detected that neuronal apoptosis marker active caspase-3 had co-localizations with BTEB2. In addition, KLF5 knockdown in vitro specifically resulted in increasing neuronal apoptosis coupled with reduced Bad phosphorylation at both ser112 and ser136 residues. All our findings suggested that BTEB2 down-regulated neuronal apoptosis via promoting Bad phosphorylation after ICH.

Up-Regulation of Podoplanin Involves in Neuronal Apoptosis in LPS-Induced Neuroinflammation

Podoplanin (PDPN) is a mucin-type transmembrane sialoglycoprotein expressed in multiple tissues in adult animals, including the brain, lungs, kidney, and lymphoid organs. Studies of this molecule have demonstrated its great importance in tumor metastasis, platelet aggregation, and lymphatic vessel formation. However, information regarding its regulation and possible function in the central nervous system is still limited. In this study, we performed a neuroinflammatory model by lipopolysaccharide (LPS) lateral ventral injection in adult rats and detected increased expression of PDPN in the brain cortex. Immunofluorescence indicated that PDPN was located in the neurons, but not astrocytes. Moreover, there was a concomitant up-regulation of active caspase-3, cyclin D1, and CDK4 in vivo and vitro studies. In addition, the expression of these three proteins in cortical primary neurons was decreased after knocking down PDPN by siRNA. Collectively, all these results suggested that the up-regulation of PDPN might be involved in neuronal apoptosis in neuroinflammation after LPS injection.

Upregulated Expression of SSTR1 is Involved in Neuronal Apoptosis and is Coupled to the Reduction of bcl-2 Following Intracerebral Hemorrhage in Adult Rats

Somatostatins are peptide hormones that regulate diverse cellular processes, such as neurotransmission, cell proliferation, apoptosis, and endocrine signaling as well as inhibiting the release of many hormones and other secretory proteins. SSTR1 is a member of the superfamily of somatostatin receptors possessing seven-transmembrane segments. Aberrant expression of SSTR1 has been implicated in several human diseases, including pseudotumor cerebri, and oncogenic osteomalacia. In this study, we investigated a potential role of SSTR1 in the regulation of neuronal apoptosis in the course of intracerebral hemorrhage (ICH). A rat ICH model in the caudate putamen was established and subjected to behavioral tests. Western blot and immunohistochemistry indicated a remarkable up-regulation of SSTR1 expression surrounding the hematoma after ICH. Double-labeled immunofluorescence showed that SSTR1 was mostly co-localized with neurons, and was rarely distributed in activated astrocytes and microglia. Additionally, SSTR1 co-localized with active-caspase-3 and bcl-2 around the hematoma. The expression of active-caspase-3 was parallel with that of SSTR1 in a time-dependent manner. In addition, SSTR1 knockdown specifically resulted in reduced neuronal apoptosis in PC12 cells. All our findings suggested that up-regulated SSTR1 contributed to neuronal apoptosis after ICH, which was accompanied with reduced expression of bcl-2.

WY14643 Attenuates the Scopolamine-Induced Memory Impairments in Mice.

WY14643 is a selective agonist of peroxisome proliferator-activated receptor-α (PPAR-α) with neuroprotective and neurotrophic effects. The aim of this study was to evaluate the effects of WY14643 on cognitive impairments induced by scopolamine, a muscarinic acetylcholine receptor antagonist. We conducted different behavior tests including the Y-maze, Morris water maze, and passive avoidance test to measure the cognitive functions of C57BL/6J mice after scopolamine and WY14643 treatment. It was found that WY14643 injection significantly attenuated the scopolamine-induced cognitive impairments in these behavioral tests. Moreover, WY14643 treatment significantly enhanced the expression of brain-derived neurotrophic factor (BDNF) signaling cascade in the hippocampus. The usage of both PPAR-α inhibitor GW6471 and BDNF system inhibitor K252a fully prevented the memory-enhancing effects of WY14643. Therefore, these findings suggest that WY14643 could improve the scopolamine-induced memory impairments, and these effects are mediated by the activation of PPAR-α and BDNF system, thereby exhibiting a cognition-enhancing potential.

Up-Regulation of Interferon Regulatory Factor 3 Involves in Neuronal Apoptosis After Intracerebral Hemorrhage in Adult Rats

Interferon regulatory factor 3 (IRF3) is a member of IRF family which plays a significant role in the innate immune response, apoptosis, and oncogenesis. Mounting evidence has demonstrated that IRF3 was involved in central nervous system disease such as cerebral ischemic injury through promoting neuronal apoptosis. However, it remains unclear about the underlying mechanisms of IRF3 upon neuronal apoptosis following intracerebral hemorrhage (ICH). In the present study, we established an adult rat ICH model by injecting autologous whole blood into the right basal ganglia and evaluated their neurological deficits by behavioral tests. IRF3 protein level was up-regulated adjacent to the hematoma following ICH when compared with the sham brain cortex by western blot and immunohistochemistry. Immunofluorescent staining indicated IRF3 was mainly localized in neurons, a few in astrocytes. In addition, we also detected that IRF3 co-localized with active caspase-3 which is a neuronal apoptosis marker. Furthermore, in vitro study, knocking down IRF3 by using IRF3 interference in primary cortical neurons reduced the expression of active caspase-3 and Bax while increased Bcl-2. In conclusion, we speculated that IRF3 might exert pro-apoptotic function in neurons after ICH.

Upregulated Expression of SSTR3 is Involved in Neuronal Apoptosis After Intracerebral Hemorrhage in Adult Rats

Somatostatin which is a multifunctional growth hormone inhibitory neuropeptide shows diverse physiological effects, such as neurotransmission, cell growth, apoptosis, and endocrine signaling as well as exerts inhibitory effects on hormonal products and other secretory proteins. SSTR3 is a member of superfamily of somatostatin receptors (SSTR), which are G-protein-coupled plasma membrane receptors. Previous studies proved that SSTR3 regulates antiproliferative signaling and apoptosis in several cells. Here, we explored a potential role of SSTR3 in the regulation of neuronal apoptosis in the course of intracerebral hemorrhage (ICH). An ICH rat model was established and assessed by behavioral tests. We found SSTR3 was significantly upregulated surrounding the hematoma after ICH by Western blot and immunohistochemistry. Double immunofluorescence-manifested SSTR3 was strikingly increased in neurons, not astrocytes or microglia. Moreover, increasing SSTR3 level was found to be accompanied by the upregulation of p53, Bax, and active caspase-3 in vivo and in vitro studies. Furthermore, we detected that neuronal apoptosis marker active caspase-3 was co-localized with SSTR3 suggesting its potential role in neuronal apoptosis. In addition, in vitro study, revealed that SSTR3 knockdown specifically resulted in reducing neuronal apoptosis in PC12 cells, which further indicated that SSTR3 might exert its pro-apoptotic function on neuronal apoptosis. All our findings suggested that upregulated SSTR3 may be involved in neuronal apoptosis after ICH.

Up-Regulation of CCT8 Related to Neuronal Apoptosis after Traumatic Brain Injury in Adult Rats

Traumatic brain injury (TBI) initiates a series of neurochemical and signaling changes that could eventually lead to neuronal apoptosis. Recent studies indicated that mature neurons cell cycle re-enter played a crucial role in neuronal apoptosis. In this study, we identified that the chaperonin containing TCP-1, subunit 8 (CCT8), as a member of class II chaperonins, was significantly upregulated following TBI. Moreover, double immunofluorescence staining revealed that CCT8 was co-expressed with neuronal nuclei (NeuN). Besides, co-localization of CCT8/active caspase 3 was detected in NeuN. We also examined the expression profiles of active caspase 3 whose changes were correlated with the expression of CCT8. All our findings suggested that CCT8 might be involved in the pathophysiology of brain after TBI.